Articles de revues sur le sujet « Chips limit temperature »

The removal of heat from electronic components, increasingly miniaturized with high power dissipation per unit volume, is a significant industrial problem to be resolved, to avoid failures due to excessive temperatures and besides to maintain performance and operating conditions. This article describes the development of a one-dimensional thermodynamic model to simulate the cooling of electronic chips belonging to inverters for stationary PV solar arrays; these are typically located in very different environments, including deserts or very hot areas, so the operating life of theirs inverter units are strongly affected by changes in external environmental conditions. Results have shown that the model allows, with very low calculation times, to quantify the effects of cooling performance and thermal load of electronics both in design and off-design conditions: the working temperature of the components was monitored as the effectiveness of the main heat exchanger vary with the exposure to the external environment over time, in terms of fouling and as the ambient air temperature changes; in this case a simple control system was simulated to limit the maximum temperature of the chips and the air flow rate of the fans. The thermal performances of two types of glycol-based refrigerant fluids have been compared.

Abstract Heterogeneous integration of logic, memory, and sensor chips on interposers (2.5D) has attracted a lot of attention as a candidate for More-than-Moore technology. For the high performance 2.5D devices, high density integration of chips with narrow spacing and high density interconnections with small pitch bonding electrodes are a key technology. In the current bonding technology, solder micro-bumps (>20 μm in diameter) and non-conductive adhesives have been adopted. There may be some limitations for high density device integration with these technologies because of the protrusion of adhesives around the chips, the thermal sliding at the bonding, and the limit of solder micro-bump minimization. Hybrid bonding with a small Cu electrode (<10 μm in diameter) is a strong candidate for improving advanced device integration technology. Our goal is to develop a new adhesive which gives no protrusion, no thermal sliding, no voids, and high electrical reliability. A spin coating thin adhesive was therefore developed. The new adhesive can be cured at 200 °C. The cured adhesive film has no tackiness and has an optically flat surface. The adhesive film can be temporarily bondable to SiO2 at room temperature. After 200 °C baking, a permanent bonding can be achieved, and there is no degradation of bonding strength and no voids even after 400 °C of baking. For the applicability to the chip-on-wafer process, the adhesive film/Si wafer can be cut into chips by blade dicing without any delamination and without any apparent particles. After bonding the adhesive/Si chip to a bare Si wafer at room temperature, the thermal sliding amount after the thermal compression process (250 °C, 10 min, 1 MPa) was less than 1 μm (under the detection limit) according to optical microscopic measurements. In addition, there was no protrusion of adhesive around the chip corner from SEM. A first trial result for hybrid bonding is also reported.

Besides the growing interest in old concepts such as temperature and entropy at the nanoscale, theories of relaxation and transport have recently regained a lot of attention. With the electronic circuits and computer chips getting smaller and smaller, a fresh look on the equilibrium and nonequilibrium thermodynamics at small length scales far below the thermodynamic limit, i.e. on the theoretical understanding of original macroscopic processes, e.g. transport of energy, heat, charge, mass, magnetization, etc., should be appropriate. Only from the foundations of a theory its limits of applicability may be inferred. This review tries to give an overview on the background and recent developments in the field of nonequilibrium quantum thermodynamics, focusing on the transport of heat in small quantum systems.

Existing passive cooling solutions limit the short-term thermal output of systems, thereby either limiting instantaneous performance or requiring active cooling solutions. As the temperature of the electronic devices increases, their failure rate increases. That’s why electrical devices should be cooled. Conventional electronic cooling systems usually consist of a metal heat sink coupled to a fan. This paper compares the heat distribution on a heat sink relative to different heat fluxes produced by electronic chips. The benefit of adding a fan is also investigated when high levels of heat generation are expected.

We propose and analyze three Si-based room-temperature strip-guided “manufacturable” integrated quantum photonic chem/bio sensor chips operating at wavelengths of 1550 nm, 1330 nm, and 640 nm, respectively. We propose design rules that will achieve super-sensitivity (above the classical limit) by means of mixing between states of coherent light and single-mode squeezed-light. The silicon-on-insulator (SOI), silicon-on-sapphire (SOS), and silicon nitride-on-SiO2-on Si (SiN) platforms have been investigated. Each chip is comprised of photonic building blocks: a race-track resonator, a pump filter, an integrated Mach-Zehnder interferometric chem/bio sensor, and a photonic circuit to perform parity measurements, where our homodyne measurement circuit avoids the use of single-photon-counting detectors and utilizes instead conventional photodetectors. A combination of super-sensitivity with super-resolution is predicted for all three platforms to be used for chem/bio sensing applications.

In this paper, we present a fully integrated Non-dispersive Infrared (NDIR) CO2 sensor implemented on a silicon chip. The sensor is based on an integrating cylinder with access waveguides. A mid-IR LED is used as the optical source, and two mid-IR photodiodes are used as detectors. The fully integrated sensor is formed by wafer bonding of two silicon substrates. The fabricated sensor was evaluated by performing a CO2 concentration measurement, showing a limit of detection of ∼750 ppm. The cross-sensitivity of the sensor to water vapor was studied both experimentally and numerically. No notable water interference was observed in the experimental characterizations. Numerical simulations showed that the transmission change induced by water vapor absorption is much smaller than the detection limit of the sensor. A qualitative analysis on the long term stability of the sensor revealed that the long term stability of the sensor is subject to the temperature fluctuations in the laboratory. The use of relatively cheap LED and photodiodes bare chips, together with the wafer-level fabrication process of the sensor provides the potential for a low cost, highly miniaturized NDIR CO2 sensor.

ABSTRACT Recent recalls and outbreaks due to foodborne pathogens in thermally processed low-moisture foods highlight the need for the food industry to validate their thermal process. The purpose of this study was to validate baking as an adequate lethality step in controlling Salmonella and Listeria monocytogenes during the production of peanut butter (PB)–filled pretzels and whole wheat (WW) pita chips. Two dough types, PB-filled pretzel and WW pita chip with varying water activities (0.96 to 0.98), were inoculated (target level, ∼108 to 109 CFU/g) with a multistrain cocktail of Salmonella and L. monocytogenes in separate trials and were baked at 300°F (148.9°C) and 350°F (176.6°C) for 0, 5, 10, 17, 25, and 30 min. Following baking, samples were rapidly cooled and analyzed for Salmonella and L. monocytogenes by the pour plate method. Uninoculated samples were analyzed for total viable aerobic plate count (APC) and Enterobacteriaceae counts. Water activity analysis was also performed. The experiment was replicated three times. Nonlinear regression was used to estimate the baking times required to achieve a minimum of 4- and 5-log reduction in APC, Salmonella, and L. monocytogenes. A 4- and 5-log reduction in APC was predicted following a treatment at 350°F for 3.3 and 5.6 min in WW pita chip product, respectively. Following a treatment of 350°F for 10 and 25 min, Enterobacteriaceae and APC counts were below the detection limit (<1 log CFU/g), respectively, in all of the PB-filled pretzel samples. Salmonella and L. monocytogenes counts decreased with increasing baking time regardless of the temperature used. Significant reductions (≥5-log reduction) were estimated in Salmonella and L. monocytogenes in product baked at 350°F for 15.5 and 17.5 min in WW pita chip dough and PB-filled pretzel dough, respectively. Both pathogens were below the detection limit (<1 log CFU/g) in PB-filled pretzel and WW pita chip products under baking conditions of 350°F for 25 and 30 min, respectively. This study demonstrates that PB-filled pretzel and WW pita chip products, when baked to saleable quality, will not present a public health risk from the standpoint of Salmonella or L. monocytogenes.

Background: Antineoplastic agents represent the most common class of drugs causing Adverse Drug Reactions (ADRs). Mutant alleles of genes coding for drug-metabolizing enzymes are the best studied individual risk factors for these ADRs. Although the correlation between genetic polymorphisms and ADRs is well-known, pharmacogenetic tests are limited to centralized laboratories with expensive or dedicated instrumentation used by specialized personnel. Nowadays, DNA chips have overcome the major limitations in terms of sensibility, specificity or small molecular detection, allowing the simultaneous detection of several genetic polymorphisms with time and costs-effective advantages. In this work, we describe the design of a novel silicon-based lab-on-chip assay able to perform low-density and high-resolution multi-assay analysis (amplification and hybridization reactions) on the In-Check platform. Methods: The novel lab-on-chip was used to screen 17 allelic variants of three genes associated with adverse reactions to common chemotherapeutic agents: DPYD (Dihydropyrimidine dehydrogenase), MTHFR (5,10-Methylenetetrahydrofolate reductase) and TPMT (Thiopurine S-methyltransferase). Results: Inter- and intra assay variability were performed to assess the specificity and sensibility of the chip. Linear regression was used to assess the optimal hybridization temperature set at 52 °C (R2 ≈ 0.97). Limit of detection was 50 nM. Conclusions: The high performance in terms of sensibility and specificity of this lab-on-chip supports its further translation to clinical diagnostics, where it may effectively promote precision medicine.

Acrylamide is a toxic chemical formed in high temperature-processed foods (e.g., Potato snacks, instant noodle, etc.). Previous studied showed that acrylamide is a carcinogenic agent in human and animals. Evaluation of acrylamide contents in some processed starchy foods has been performed in order to investigate the presence of acrylamide in foods in Hanoi. This study is to validate a LC-MS/MS method for determination of acrylamide in food and to determine the acrylamide content in some processed starchy foods available in Hanoi, Vietnam. Samples of potato chips collected from food shops in Hanoi were tested. The acrylamide content was determined by high performance liquid chromatography-mass spectrometry. The method was validated for accuracy, precision, linearity, and recovery. The assay was linear over the entire range of calibration standards i.e., a concentration range from 1 ng/mL to 2500 ng/mL (r2 >0.996). The precision and recoveries were obtained based on the AOAC guidelines. The lower limit of quantification of the analytical method of acrylamide was 24,82 ng/mL. The validated method was successfully applied to determine acrylamide in 28 samples of potato snacks. The content of acrylamide ranged from 58.0 to 1829.6 mg/kg. Acrylamide was detected in all samples, nevertheless, the acrylamide content was lower than that from other studies published in 2009 in Europe.  

With the rapid development of the Information Technology (IT) industry, the heat flux in integrated circuit (IC) chips cooled by air has almost reached its limit at about 100W∕cm2. Some applications in high technology industries require heat fluxes well beyond such a limitation. Therefore, the search for a more efficient cooling technology becomes one of the bottleneck problems of the further development of the IT industry. The microchannel flow geometry offers a large surface area of heat transfer and a high convective heat transfer coefficient. However, it has been hard to implement because of its very high pressure head required to pump the coolant fluid through the channels. A normal channel size could not give high heat flux, although the pressure drop is very small. A minichannel can be used in a heat sink with quite a high heat flux and a mild pressure loss. A minichannel heat sink with bottom size of 20mm×20mm is analyzed numerically for the single-phase turbulent flow of water as a coolant through small hydraulic diameters. A constant heat flux boundary condition is assumed. The effect of channel dimensions, channel wall thickness, bottom thickness, and inlet velocity on the pressure drop, temperature difference, and maximum allowable heat flux are presented. The results indicate that a narrow and deep channel with thin bottom thickness and relatively thin channel wall thickness results in improved heat transfer performance with a relatively high but acceptable pressure drop. A nearly optimized structure of heat sink is found that can cool a chip with heat flux of 350W∕cm2 at a pumping power of 0.314W.

To provide pork processors with valuable data to validate the critical limits set for temperature during pork fabrication and grinding, a study was conducted to determine the growth of Salmonella serotypes and background flora at various temperatures. Growth of Salmonella Typhimurium and Salmonella Enteritidis and of background flora was monitored in ground pork and boneless pork chops held at various temperatures to determine growth patterns. Case-ready modified atmosphere packaged ground pork and fresh whole pork loins were obtained locally. Boneless chops and ground pork were inoculated with a cocktail mixture of streptomycin-resistant Salmonella to facilitate recovery in the presence of background flora. Samples were held at 4.4, 7.2C, and 10°C and at room temperature (22.2 to 23.3°C) to mimic typical processing and holding temperatures observed in pork processing environments. Salmonella counts were determined at regular intervals over 12 and 72 h for both room and refrigeration temperatures. No significant growth of Salmonella (P < 0.05) was observed in boneless pork chops held at refrigeration temperatures. However, Salmonella in boneless pork chops held at room temperature had grown significantly by 8 h. Salmonella grew at faster rates in ground pork. Significant growth was observed at 6, 24, and 72 h when samples were held at room temperature, 10°C, and 7.2°C, respectively. No significant growth was observed at 4.4°C. Background flora in ground pork samples increased significantly after 10 h at room temperature and after 12 h for samples held at 10 and 7.2°C. Background flora in samples held at refrigeration temperatures did not increase until 72 h. Background flora in the boneless chops increased significantly after 6 h at room temperature and after 24 h when held at 10 and 4.4°C. These results illustrate that meat processors can utilize a variety of time and temperature combinations as critical limits to minimize Salmonella growth during production and storage of raw pork products.

This paper investigated the machinability of a stone–plastic composite (SPC) via orthogonal cutting with diamond cutters. The objective was to determine the effect of cutting depth on its machinability, including cutting forces, heat, chip formation, and cutting quality. Increased cutting depth promoted an increase in both frictional and normal forces, and also had a strong influence on the change in normal force. The cutting temperatures of chips and tool edges showed an increasing trend as cutting depth increased. However, the cutting heat was primarily absorbed by chips, with the balance accumulating in the cutting edge. During chip formation, the highest von Mises strain was mainly found in SPC ahead of the cutting edge, and the SPC to be removed partially passed its elastic limit, eventually forming chips with different shapes. Furthermore, the average surface roughness and the mean peak-to-valley height of machined surfaces all positively correlated to an increase in cutting depth. Finally, with an increase in cutting depth, the chip shape changed from tubular, to ribbon, to arc, to segmental, and finally, to helical chips. This evolution in chip shape reduced the fluctuation in cutting force, improving cutting stability and cutting quality.

AbstractKnowledge about the hydraulic connections between submarine groundwater discharge (SGD) and its terrestrial coastal catchment is relevant with regard to the management of marine and coastal waters in karst areas. This study applies different methods and monitoring approaches to trace SGD between the Burren Limestone Plateau and Galway Bay in western Ireland, via an excavated sinkhole shaft and deep conduit. Areas of potential SGD were first delineated based on sea surface temperature anomalies using Landsat satellite images. Two fluorescent dyes and solid wood chips were then used as tracers. Solid wood chips were tested as potential means to circumvent the problem of high dispersion in the sea, impacting on the fluorescent dyes to yield readings below the detection limits. Sampling was conducted at 10 different terrestrial locations and in the sea at Galway Bay. Offshore sampling was conducted in transects over a period of four successive days onboard of a vessel using an automated field fluorometer and a conductivity-temperature-depth sensor. No wood chips were recovered in the sea but both fluorescent dyes were successfully sampled. The estimated travel times are in the order of 100 to 354 m/h, and localised tracer readings correlate well in space and time with low conductivity readings. By confirming hydraulic connections between the two karst features and Galway Bay, the study substantiates the hypothesised importance of Variscan veins with regard to regional groundwater flow in the region.

The high incidence of lung cancer observed among Chinese women has been associated with exposure to fumes from cooking oil. Polycyclic aromatic hydrocarbons (PAHs) are a class of potentially mutagenic substances emitted from cooking oils heated at high temperatures. The objective of this study was to investigate whether deep frying with different oils under different conditions leads to the development of PAHs either in the oil or in the fried product (snacks). PAH analysis was carried out with solid-phase extraction followed by reverse-phase high-performance liquid chromatography and spectrofluorometric detection. Different oils were used to fry chips and extruded snacks in different industrial plants (continuous frying) at temperatures between 170 and 205°C, and peanut oil was used to fry French fries and fish (discontinuous frying) at temperatures between 160 and 185°C. No appreciable differences in PAH load was observed in the same oil before and after frying. Both before and after frying, the benzo[a]pyrene concentration in oils ranged from trace to 0.7 ppb. All the analyzed samples, including oils from fried snacks, had benzo[a]pyrene concentrations well below the 2 ppb limit recently proposed by the European Community.

This paper gives comparison and discussion of adhesives used for attachment of silicon piezoresistive pressure sensor dies. Special attention is paid on low pressure sensor dies because of their extreme sensitivity on stresses, which can arise from packaging procedure and applied materials. Commercially available adhesives ?Scotch Weld 2214 Hi-Temp? from ?3M Co.? and ?DM2700P/H848? from ?DIEMAT?, USA, were compared. First of them is aluminum filled epoxy adhesive and second is low melting temperature (LMT) glass paste. Comparing test results for low pressure sensor chips we found that LMT glass (glass frit) is better adhesive for this application. Applying LMT glass paste minimizes internal stresses caused by disagreement of coefficients of thermal expansions between sensor die and housing material. Also, it minimizes stresses introduced during applying external loads in the process of pressure measuring. Regarding the measurements, for the sensors installed with filled epoxy paste, resistor for compensation of temperature offset change had negative values in all cases, which means that linear temperature compensation, of sensors installed this way, would be impossible. In the sensors installed with LMT glass paste, all results, without exception, were in their common limits (values), which give the possibility of passive temperature compensation. Furthermore, LMT glass attachment can broaden temperature operating range of MEM silicon pressure sensors towards higher values, up to 120 ?C.

The embedding of active and passive components offers a wide range of benefits and potentials. With the use of laminate based technology concepts, components can be moved from surface mount into the build-up layers of substrates by embedding and by that, the third dimension will be available for further layers or assemblies. This paper will briefly discuss the necessary process steps of the embedded chip technology and more importantly it will focus on new efforts to actually use chip embedding concepts for the realization of standard-type industrial Quad Flat Packages with embedded chips (embedded chip QFN). Chips of 50 μm thickness, a pad pitch of 100 μm and pad size of 85 μm are die bonded to a copper substrate and subsequently embedded in RCC (Resin-Coated-Copper) layers by using vacuum lamination. The resulting QFN packages are only 160 μm thick and provide standard pads at 400 μm pitch and a total number of 84 I/Os with dimensions of 10x10 mm2. All embedded chip QFN packages at prototype level are manufactured in 250x300 mm2 panels. The present work will include QFN package reliability results after extensive testing of thermal cycling, temperature humidity, high temperature storage and pressure cooker test. The investigation of new embedding material combinations is one task to provide a reliable package. The main focus here is on new materials that offer improved package stability and also the ability to embed dies of different thickness. Together with material suppliers improved resin formulations as well as the introduction of filler and glass fibers into the resin layers is currently realized and tested. In order to realize a further miniaturization ultra fine pitch (UFP) and fine line (UFL) approaches will be presented. For a UFP approach the goal is to develop the laser via technology further towards their limits as well as the investigation of new concepts. UFP requires the use of a semi additive patterning process. Here LDI processing is being used for all new generation chip embedded packages due to its potential for very fine copper patterning. Results on very fine L/S of 15–20μm will be shown based on the semi-additive processes on an ultra thin initial 1–2μm copper foil. Finally different applications will be presented. In an industrial cooperation different power package developments are ongoing. Here single and multi chips modules are realized as well as multiple routing layers. The combination of power and logic is one of the main challenges here, due to the need of thick copper layers for the power part and the more fine pitch demands for the controller chips. Process developments and results will be discussed in detail.

A novel electrochemical immunosensor for determination of carcinoembryonic antigen (CEA) in human serum was fabricated by depositing Mo–Mn3O4/MWCNTs/Chits nanocomposite onto an indium-tin oxide (ITO) electrode. Mo-doped Mn3O4 (MMO) was synthesized by sol–gel method and the presence of molybdenum improved its electrochemical properties. The MMO/MWCNTs/Chits nanocomposite could accelerate the electron transfer rate and enlarge the surface area to capture a large number of Carcinoembryonic Antigen (CEA). The factors influencing the performance of the immunosensor were investigated, such as incubation time, incubation temperature and pH. Under optimal conditions, the electrochemical immunosensor could detect CEA in a linear range from 0.1[Formula: see text]ng[Formula: see text][Formula: see text][Formula: see text]mL[Formula: see text] to 125[Formula: see text]ng[Formula: see text][Formula: see text][Formula: see text]mL[Formula: see text] with a detection limit of 4.9[Formula: see text]pg[Formula: see text][Formula: see text][Formula: see text]mL[Formula: see text] ([Formula: see text][Formula: see text]). In addition, it exhibited high sensitivity and acceptable stability on a promising immobilization platform for signal amplification, which could be extended to other labeled recognition systems. This electrochemical immunosensor may provide potential applications for the clinical diagnosis.

The heterogeneity of biogenic fuels, and especially biogenic residues with regard to water and ash content, particle size and particle size distribution is challenging for biomass combustion, and limits fuel flexibility. Online fuel characterization as a part of process control could help to optimize combustion processes, increase fuel flexibility and reduce emissions. In this research article, a concept for a new sensor module is presented and first tests are displayed to show its feasibility. The concept is based on the principle of hot air convective drying. The idea is to pass warm air with 90 °C through a bulk of fuel like wood chips and measure different characteristics such as moisture, temperatures and pressure drop over the bulk material as a function over time. These functions are the basis to draw conclusions and estimate relevant fuel properties. To achieve this goal, a test rig with a volume of 0.038 m3 was set up in the laboratory and a series of tests was performed with different fuels (wood chips, saw dust, wood pellets, residues from forestry, corn cobs and biochar). Further tests were carried out with conditioned fuels with defined water and fines contents. The experiments show that characteristic functions arise over time. The central task for the future will be to assign these functions to specific fuel characteristics. Based on the data, the concept for a software for an automated, data-based fuel detection system was designed.

Recent advances in synchrotron sources, beamline optics and detectors are driving a renaissance in room-temperature data collection. The underlying impetus is the recognition that conformational differences are observed in functionally important regions of structures determined using crystals kept at ambient as opposed to cryogenic temperature during data collection. In addition, room-temperature measurements enable time-resolved studies and eliminate the need to find suitable cryoprotectants. Since radiation damage limits the high-resolution data that can be obtained from a single crystal, especially at room temperature, data are typically collected in a serial fashion using a number of crystals to spread the total dose over the entire ensemble. Several approaches have been developed over the years to efficiently exchange crystals for room-temperature data collection. These includein situcollection in trays, chips and capillary mounts. Here, the use of a slowly flowing microscopic stream for crystal delivery is demonstrated, resulting in extremely high-throughput delivery of crystals into the X-ray beam. This free-stream technology, which was originally developed for serial femtosecond crystallography at X-ray free-electron lasers, is here adapted to serial crystallography at synchrotrons. By embedding the crystals in a high-viscosity carrier stream, high-resolution room-temperature studies can be conducted at atmospheric pressure using the unattenuated X-ray beam, thus permitting the analysis of small or weakly scattering crystals. The high-viscosity extrusion injector is described, as is its use to collect high-resolution serial data from native and heavy-atom-derivatized lysozyme crystals at the Swiss Light Source using less than half a milligram of protein crystals. The room-temperature serial data allowde novostructure determination. The crystal size used in this proof-of-principle experiment was dictated by the available flux density. However, upcoming developments in beamline optics, detectors and synchrotron sources will enable the use of true microcrystals. This high-throughput, high-dose-rate methodology provides a new route to investigating the structure and dynamics of macromolecules at ambient temperature.

Remote measurement of product core temperature is an important prerequisite to improve the cool chain of food products and reduce losses. This paper examines and shows possible solutions to technical challenges that still hinder practical applications of wireless sensor networks in the field of food transport supervision. The high signal attenuation by water-containing products limits the communication range to less than 0.5 m for the commonly used 2.4 GHz radio chips. By theoretical analysis of the dependency of signal attenuation on the operating frequency, we show that the signal attenuation can be largely reduced by the use of 433 MHz or 866 MHz devices, but forwarding of messages over multiple hops inside a sensor network is mostly unavoidable to guarantee full coverage of a packed container. Communication protocols have to provide compatibility with widely accepted standards for integration into the global Internet, which has been achieved by programming an implementation of the constrained application protocol for wireless sensor nodes and integrating into IPv6-based networks. The sensor's battery lifetime can be extended by optimizing communication protocols and by in-network pre-processing of the sensor data. The feasibility of remote freight supervision was demonstrated by our full-scale ‘Intelligent Container’ prototype.

Abstract In 2004, a quantitative headspace (HS) gas chromatographic/mass spectrometric method was developed and used to determine furan in approximately 300 foods. This method was modified and validated for the determination of furan in low-moisture snack foods. The modifications include a smaller test portion size and lower HS oven temperature. The limits of detection ranged from 0.4 ng/g in graham crackers to 4.4 ng/g in pretzels. Recoveries from samples fortified at 0.5, 1, 2, and 3 times the levels of incurred furan found in the samples ranged from 96 to 102, and HorRat values showed that the recovery data met the criteria for repeatability. The modified method was shown to be reliable for the determination of furan in foods when test portions were equilibrated for 30 min in a 60C HS oven. The modified method was used to conduct a survey of furan in 22 low-moisture snack foods. All of the samples were found to contain furan ranging from 3.7 ng/g in graham crackers to 60 ng/g in corn chips. Results from the survey were consistent with results obtained for similar snack foods analyzed by a U.S. Food and Drug Administration field laboratory.

As a highly efficient heat transfer component, a micro heat pipe (MHP) has been widely applied to the situations with high heat flux concentration. However, a MHPs heat transfer performance is affected by many factors, among which, working fluid inventory has great influence on the security, reliability and frost resistance of its heat transfer performance. In order to determine the appropriate working fluid inventory for grooved MHPs, this paper first analyzed the working principle, major heat transfer limits and heat flux distribution law of grooved MHPs in electronic chips with high heat flux concentration, then established a mathematic model for the working fluid inventory in grooved MHPs. Finally, with distilled water being the working fluid, a series of experimental investigations were conducted at different temperatures to test the heat transfer performances of grooved MHPs, which were perfused with different inventories and with different adiabatic section lengths. The experimental results show that when the value of α is roughly within 0.40±0.05, a grooved MHP can acquire its best heat transfer performance, and the working fluid inventory can be determined by the proposed mathematic model. Therefore this study solves the complicated problem of determining appropriate working fluid inventory for grooved MHPs.

Thin film polymers, like PI, PBO and BCB are used in every wafer level packaging device. The improvement of the reliability of wafer-level packages and chip I/Os consider the choice of the polymer, which is used as dielectric on the chip, as a minor point. Because the production lines are normally fixed on one polymer and the high investments to evaluate the processing of an alternative polymer formulation in combination with costly reliability test seems to be not attractive till today. But the increased demands of advanced WLP and 3-D-Integration, which includes thin chips, chips stacking and higher routing densities, leads to reaching the limits of the common used material system combinations. The demand of better polymer films becomes evident by the fact that dozens of “next generation polymers” have entered the marked in the last years, which are tailored to get higher mechanical toughness and electrical performance aside of a nearly unchanged resolution capacity. The challenge for new polymer formulation is the evaluation of the processing and the generation of a reliable material property data base, which set the basics for any benchmarking to the already used polymer materials. The processing evaluation is done typically by the material supplier or the fab himself, where no special equipment is needed. The material property generation is a quite more complex topic because you need special equipment and partly the material need to be free standing without any substrate. This is also a handling issue, if we talk about thin films in the range of 5 to 20μm. This paper presents the reliable thin film polymer properties characterization of mechanical and electrical values. The measurements of the mechanical properties include the estimation of parameters like young's modulus, tensile strength, elongation at break, coefficient of thermal expansion, stress and time-temperature related effects. The evident topic of warpage related impacts by “new generation polymers” will be presented and discussed. Measurement structures on wafer-level are developed for the estimation of the electrical parameters, which allows a high accuracy and a device relevant value estimation. Parameters like break down voltage, leakage current, dielectric constant, loss factor are measured related to frequencies by MIM and resonator structures. We demonstrate with analyzing of the time-dependent dielectric breakdown (TDDB) of thin film polymers that there is an exponential linkage between field strength and the time till the breakthrough occurs. The mechanical and electrical properties were also investigated related to aging effects, when the application is running on elevated temperature. We examine a degradation of the mechanical and electrical performance, which should be taken into account for the mechanical system reliability and also for impedance controlled HF-application. This paper present advanced material characterization of thin film polymers which gives a guideline for the decision of the polymer related to the demands of the application.

This contribution gives an overview of the current state, performance, and limitations of the fast-response aerodynamic probe measurement system developed at the Turbomachinery Lab of the ETH Zurich. In particular, the following topics are addressed: • Probe technology: Miniature probes with tip diameter ranging from 0.84 to 1.80 mm (one-sensor and three-sensor probes, respectively) have been developed. New technologies derived from microelectronics and micromechanics have been used to achieve an adequate packaging of the microsensor chips used. Both the sensor packaging and the sensor calibration (time-independent and time-dependent) are crucial issues for the DC accuracy of any measurement. • Aerodynamic probe calibration: The methods used for the sensor calibration and the aerodynamic probe calibration, the pertinent automated test facilities, and the processing of the output data are briefly presented. Since these miniature probes are also capable of measuring the mean flow temperature, aspects related to the effective recovery factor and the self-heating of the probe tip are treated and some recommendations related to sensor selection are given. • Measurement system and data evaluation: The early measurement chain described in Gossweiler et al. (1995) has evolved into the fast-response aerodynamic probe system. This automatic system incorporates dedicated measurement concepts for a higher accuracy and a more efficient operation in terms of time and failures. An overview of the data evaluation process is given. The fast-response aerodynamic probe system has been tested in real-sized turbomachines under industrial conditions within the temperature limits of 140°C imposed by the sensor technology (axial-flow turbofan compressor, axial-flow turbine, centrifugal compressor). These applications confirmed the potential of the system and encouraged its further development. Now, the system is routinely used in the facilities of the Turbomachinery Lab and in occasional measurement campaigns in other laboratories. Part 2 of this contribution (Roduner et al.) will focus on the application of the fast-response aerodynamic probe system in a transonic centrifugal compressor of the ETH Turbomachinery Laboratory, while Part 3 (Ko¨ppel et al.) treats more sophisticated data analysis methods. [S0889-504X(00)01003-5]

In situ sensors can measure wire bond reliability nondestructively during thermal aging. Conventional thermal aging of ball bonds requires ovens heating the entire microchip along with the wire bonds, also affecting interconnects for in situ sensors. To protect the interconnects and on-chip logic components of in situ sensor chips, conventional thermal aging is kept below a safe temperature limit of 200 °C. At higher temperatures, the doped Si components change their characteristics and transistors stop working. Localized on-chip heating is introduced to circumvent these drawbacks using a new microheater to increase the safe temperature limit for nondestructive reliability assessment with in situ sensors. The effect of temperature on surrounding components is reduced. The microheater is a rectangular design resistive heater made from N+ silicon. In addition, a pad resistance measurement is introduced that indicates bond aging more conveniently than previously reported bond resistance measurements.

ABSTRACTIn Korea Depleted Uranium(DU) is used in manufacturing a metallic nuclear fuel for the Korean Multi-Purpose Research Reactor(KMRR). In the manufacturing processes it produces DU chips and scraps as a waste material which composed of U-Ti, U-Zr, U-Mo and U-Si intermetallic compound. In this study Air Controlled Oxidizer(ACO) has been developed which facilitates DU to be converted into U308, the most stable form of uranium. Since DU chips oxidize rapidly and their heat of oxidation is very high(4.199kJ/g, U3O8), the inside temperature of the oxidizer is likely going up rapidly. Therefore the oxidizer must be able to be cooled properly or temperature increasement of the oxidizer must be under control. Kang et al.[1] reported for the oxidation of U-0.75wt%/o Ti chips in air that U308 was detected at the temperature above 350°C. And they[2] also reported that the maximum heat generation per unit time during oxidation was as follows:where Q was the maximum heat generation per unit timeWDU was the weight of DU loaded in ACOdw/dt was the reaction rateVair was the flow rate of input airR was the universal gas constantand T was the absolute temperature.From eq.(1) the maximum heat generation per unit time during oxidation is only function of the weight of DU loaded in ACO and the oxidation rate which is dependent on the oxidation temperature or the flow rate of input air.The ACO consists of an air flow meter, an air heater, an oxidation chamber with inner heater(capacity 7.5kW), an ash collection tank, a fly ash collector, a pressure gauge, a safety valve, and a soaking tank. The air flow meter is used to control the flow rate of input air below theoretical air requirement limit for the complete oxidation of DU. The inner heater is used to heat the inside of the oxidizer to an optimum oxidation temperature. The ash collection tank is used to collect uranium oxide powder after completion of oxidation. The fly ash collector is used both to collect flying ashes and to condense vaporized uranium oxide. Also, in ACO, DU chips are not ignited directly in order to prevent rapid temperature increasement. The oxidation environment only is achieved by heating the inside of oxidizer.To find effect of the oxidation temperature on the temperature of the oxidation chamber during treatment of DU, we conduct the experiment by changing heating rates of inner heater, 3, 4, 5 and 6kW, respectively. We conduct experiments for 120 minute with 2/min input air. However, it turned out that the complete oxidation is reached within 60 minute. After complete oxidation the weight gains of the DU chips is from 4.5 to 5.0 wt0/o and the DU chips are pulverized and they are converted to U 08 and 979 Mat. Res. Soc. Symp. Proc. Vol. 506 1998 Materials Research Society During the oxidation, maximum temperature increases to 470, 497.5, 572.5 and 6771C for heating rates 3, 4, 5 and 6kW, respectively. As the temperatures of the oxidation chamber outside surface are not exceed 1501C, however, DU chips are treated safely. In each experiment, weight before and after oxidation, the oxide forms of the product and the maximum temperature in the oxidation chamber during oxidation are shown in table 1. The maximum temperature profiles of the chamber inside and surface for time and heating rates are shown in Fig. I and 2, respectively.

Abstract In modern electronics and optoelectronics, hot electron behaviors are highly concerned since they determine the performance limit of a device or system, like the associated thermal or power constraint of chips, the Shockley-Queisser limit for solar cell efficiency. Up-to-date, however, the manipulation of hot electrons is mostly based on conceptual interpretations rather than a direct observation. The problem arises from a fundamental fact that energy-differential electrons are mixed up in real-space, making it hard to distinguish them from each other by standard measurements. Here we demonstrate a distinct approach to artificially (spatially) separate hot electrons from cold ones in semiconductor nanowire transistors, which thus offers a unique opportunity to observe and modulate electron occupied state, energy, mobility, and even its path. Such a process is accomplished through the scanning-photocurrent-microscopy (SPCM) measurements by activating the intervalley-scattering events and one-dimensional charge-neutrality rule. Findings discovered here may provide a new degree of freedom in manipulating nonequilibrium electrons for both electronic and optoelectronic applications.

AbstractGas sensing technologies are of importance for a variety of industrial, environmental, medical, and even military applications. Many gases, such as man-made or naturally occurring volatile organic compounds (VOCs), can adversely affect human health or cause harm to the environment. Recent advances in “designer solvents” and sensor technologies have facilitated the development of ultrasensitive gas sensing ionic liquids (SILs) based on quartz crystal microbalance (QCM) that can real-time detect and discriminate VOCs. Based on specific chemical reactions at room temperature, thin-coated functionalized ionic liquids on quartz chips are able to capture VOCs chemoselectively with a single-digit parts-per-billion detection limit. The amalgamation of tailor-made functional SILs and QCM results in a new class of qualitative and semiquantitative gas sensing device, which represents a prototype of electronic nose. This review vignettes some conventional gas sensing approaches and collates latest research results in the exploration of SIL-on-QCM chips and gives an account of the state-of-the-art gas sensing technology.

AbstractThe microelectronics industry is pushing the fundamental limit on the physical size of individual elements to produce faster and more powerful integrated chips. These chips have nanoscale features that dissipate power resulting in nanoscale hotspots leading to device failures. To understand the reliability impact of the hotspots, the device needs to be tested under the actual operating conditions. Therefore, the development of high-resolution thermometry techniques is required to understand the heat dissipation processes during the device operation. Recently, several thermometry techniques have been proposed, such as radiation thermometry, thermocouple based contact thermometry, scanning thermal microscopy, scanning transmission electron microscopy and transition based threshold thermometers. However, most of these techniques have limitations including the need for extensive calibration, perturbation of the actual device temperature, low throughput, and the use of ultra-high vacuum. Here, we present a facile technique, which uses a thin film contact thermometer based on the phase change material $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 , to precisely map thermal contours from the nanoscale to the microscale. $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 undergoes a crystalline transition at $$\hbox {T}_{{g}}$$ T g with large changes in its electric conductivity, optical reflectivity and density. Using this approach, we map the surface temperature of a nanowire and an embedded micro-heater on the same chip where the scales of the temperature contours differ by three orders of magnitude. The spatial resolution can be as high as 20 nanometers thanks to the continuous nature of the thin film.

Static headspace gas chromatographic method for determination of hexanal as a marker of lipid oxidation was developed. Tetradecane was suggested as a matrix for hexanal release from the sample. Sample equilibration temperature and time, tetradecane volume, injection time were optimized. Benzaldehyde was selected as an internal standard. Under the optimized conditions quality parameters were determined. The calibration curve was linear in the concentration range from 25 µg l–1 to 2 g l–1, the detection limit was 15 µg l–1, RSD was determined by five replication analysis with hexanal concentration 0.1 g l–1 and was 1.2%. The technique was applied for hexanal determination in potato chips and fried potatoes.

Purpose: The purpose of this study was to compare calibration factors for deep dose equivalent Hp (10) and shallow dose equivalent Hp (0.07) between Cesium (Cs)-137 and X-ray sources when they are exposed to same dose and to determine uncertainties with MTS-N (LiF: Mg, Ti) chips when they are exposed to low dose ≤ 2mGy. Material and Methods: Thermoluminescent (TL) chips were annealed at 400oC for one hour and allowed to cool and were subjected to a temperature of 100oC for another two hours using a TLD Furnace Type LAB-01/400. They were then taken to a Secondary Standard Dosimetry Laboratory (SSDL) for irradiation using a Cs-137 source at known doses (0.2-2mGy). A RadPro Cube 400 manual TLD Reader was used to determine corresponding TL signal. The above process was replicated but with a calibrated X-ray unit as the source for calibration. Results: The calibration factors (CF) from the line graph of dose (mGy) against TL signal (count) for Cs-137 source with Hp (10) and Hp (0.07) were 3.72 x 10-6 and 5.97x10-6 mGy/count respectively. Those with X-ray source for Hp (10) and Hp (0.07) were 3.44x10-6 and 4.05x10-6 mGy/count respectively with an overall coefficient of determination (R2) = 0.99. The adjusted maximum percentage deviation between the actual and calculated dose for both sources was -2.74%. The percent (%) deviation of the mean with both sources for Hp (10) and Hp (0.07) was 3.9% and 19% respectively. Conclusion: Adjusted percent deviation from both sources were within the recommended dose limit of ±30% by the Radiological Protection Institute of Ireland (RPII) and within the International Commission on Radiological Protection (ICRP) limit respectively. Better accuracy was seen for Hp (10) with both sources compared to Hp (0.07). Calibration of the MTS-N chips using both sources was successful and can be used for personal dosimetry.

Abstract 3-Monochloropropane-1,2-diol (3-MCPD) esters and glycidyl esters (GE) are heat-induced contaminants which form during oil refining process, particularly at the high temperature deodorization stage. It is worth to investigate the content of 3-MCPD and GE in fries which also involved high temperature. The content of 3-MCPD esters and GE were monitored in fries. The factors that been chosen were temperature and duration of frying, and different concentration of salt (NaCl). The results in our study showed that the effect was in the order of concentration of sodium chloride < frying duration < frying temperature. The content of 3-MCPD esters was significantly increased whereas GE was significantly decreased, when prolong the frying duration. A high temperature results in a high 3-MCPD ester level but a low GE level in fries. The present of salt had contributed significant influence to the generation of 3-MCPD. The soaking of potato chips in salt showed no significant effect on the level of GE during the frying. The oil oxidation tests showed that all the fries were below the safety limit. Hence, the frying cycle, temperature and the added salt to carbohydrate-based food during frying should be monitored.

Abstract The industry shift to multicore microprocessor architecture will likely cause higher temperature nonuniformity on chip surfaces, exacerbating the problem of chip reliability and lifespan. While advanced cooling technologies like two phase embedded cooling exist, the technological risks of such solutions make conventional cooling technologies more desirable. One such solution is remote cooling with heatsinks with sequential conduction resistance from chip to module. The objective of this work is to numerically demonstrate a novel concept to remotely cool chips with hotspots and maximize chip temperature uniformity using an optimized flow distribution under constrained geometric parameters for the heatsink. The optimally distributed flow conditions presented here are intended to maximize the heat transfer from a nonuniform chip power map by actively directing flow to a hotspot region. The hotspot-targeted parallel microchannel liquid cooling design is evaluated against a baseline uniform flow conventional liquid cooling design for the industry pressure drop limit of approximately 20 kPa. For an average steady-state heat flux of 145 W/cm2 on core areas (hotspots) and 18 W/cm2 on the remaining chip area (background), the chip temperature uniformity is improved by 10%. Moreover, the heatsink design has improved chip temperature uniformity without a need for any additional system level complexity, which also reduces reliability risks.

This study presents the design details and the performance analyses carried out with Eloumah 1, the solar drier of cassava tuberous roots reduced in granules and microchips. Eloumah 1 is composed by a solar collector, a drying chamber and a box of rectangular section that joins the two previous components. In this solar drier the wet agricultural products are dried on the basis of the heat flux buoyancy that is induced by the difference in temperature and humidity in its compartments. Analyses of masses evaporated water of zizila and Obama (TME 419) granules and microchips tuberous roots varieties have been carried out in order to estimate the drying performance of Eloumah 1 and to know the natural laws of the drying process. The results show that Eloumah 1 is able to dry granules and microchiphs and to reduce their moisture contain to less than 10%. Moreover, it can be established that the drying process is a logistic process because in wet control samples, moisture contain has limited value. Therefore, the drying process cannot extract the free water beyond this limit value. The logistic function adjusts well these data based on the correlation coefficient (R2) and chi square coefficient (χ2).

Miniaturization of electronic and optoelectronic devices and circuits and increased switching speeds have exasperated localized heating problems. Steady-state and transient characterization of temperature distribution in devices and interconnects is important for performance and reliability analysis. Novel devices based on nanowires, carbon nanotubes, and single molecules have feature sizes in 1–100 nm range, and precise temperature measurement and calibration are particularly challenging. In this paper we review various microscale and nanoscale thermal characterization techniques that could be applied to active and passive devices. Solid-state microrefrigerators on a chip can provide a uniform and localized temperature profile and they are used as a test vehicle in order to compare the resolution limits of various microscale techniques. After a brief introduction to conventional microthermocouples and thermistor sensors, various contact and contactless techniques will be reviewed. Infrared microscopy is based on thermal emission and it is a convenient technique that could be used with features tens of microns in size. Resolution limits due to low emissivity and transparency of various materials and issues related to background radiation will be discussed. Liquid crystals that change color due to phase transition have been widely used for hot spot identification in integrated circuit chips. The main problems are related to calibration and aging of the material. Micro-Raman is an optical method that can be used to measure absolute temperature. Micron spatial resolution with several degrees of temperature resolution has been achieved. Thermoreflectance technique is based on the change of the sample reflection coefficient as a function of temperature. This small change in 10−4–10−5 range per degree is typically detected using lock-in technique when the temperature of the device is cycled. Use of visible and near IR wavelength allows both top surface and through the substrate measurement. Both single point measurements using a scanning laser and imaging with charge coupled device or specialized lock-in cameras have been demonstrated. For ultrafast thermal decay measurement, pump-probe technique using nanosecond or femtosecond lasers has been demonstrated. This is typically used to measure thin film thermal diffusivity and thermal interface resistance. The spatial resolution of various optical techniques can be improved with the use of tapered fibers and near field scanning microscopy. While subdiffraction limit structures have been detected, strong attenuation of the signal reduces the temperature resolution significantly. Scanning thermal microscopy, which is based on nanoscale thermocouples at the tip of atomic force microscope, has had success in ultrahigh spatial resolution thermal mapping. Issues related to thermal resistance between the tip and the sample and parasitic heat transfer paths will be discussed.

Snack foods are widely consumed in today's modern diet. Food processing techniques and food composition may increase advanced glycation products (AGEs) in snack foods. The present study aimed to determine the most potent precursors of AGEs in snack foods. For this purpose, commonly consumed some snacks foods were obtained from markets in Istanbul, Turkey. The amount of α dicarbonyl compounds (α-DCs,) glyoxal (GO), and methylglyoxal (MGO) were determined by high-performance liquid chromatography. The measured amount of GO and MGO ranged between 4-684 µg / 100 g and 28-1573 µg / 100 g in snack foods, respectively. In our study, high levels of MGO were detected in wafer hazelnut chips with cheese and peanuts. Due to their high-fat content, the formation of GO and MGO may occur through lipid peroxidation. In addition, the fragmented state of hazelnuts and peanuts in samples may increase lipid peroxidation. Free sugar content in Turkish delight and cake with fruit might contribute to the α-DCs formation by caramelization reaction due to high temperature. In conclusion, snack products that are frequently consumed have many unfavorable features for health. It is important to limit snack food consumption in terms of reducing AGEs exposure.

ABSTRACTGold-tin braze is the preferred material for attaching high-precision MEMS inertial sensors within hermetic ceramic packages. The bonds can be made at relatively low temperatures, are mechanically robust, and outgas at very low rates in vacuum sealed packages. There is one significant limitation to Au-Sn bonds, however. The thermal expansion coefficients of MEMS die and ceramic packages are not perfectly matched and temperature gradients occur when the assembly is cooled after brazing. As a result, there is considerable residual stress in the bonded assembly, which is accommodated to some extent by distortion of the sensor die. Over time, as these stresses relax, the distortion of the die changes, which causes the spacing between elements of the integral MEMS sensor to change as well. An important element of sensor-package design is insuring that stress relaxation effects do not cause the instrument to drift beyond its performance specification limits over a typical lifetime of 20 years.Even though Au-Sn has been used for decades to attach silicon chips to ceramic substrates, there is little data available, particularly at low temperatures. An oven, with a specially designed window, allowed in-situ measurements to be made as a function of temperature, joint thickness and load stress. Additionally, a MEMS device brazed to a package with Au-Sn has been measured interferometrically over time to quantify die distortion in a packaged application.

ABSTRACTGaAs Schottky barrier diodes remain a workhorse technology for submillimeter-wave applications including radio astronomy, chemical spectroscopy, atmospheric studies, plasma diagnostics and compact range radar. This is because of the inherent speed of these devices and their ability to operate at room temperature. Although planar (flip-chip and beam-lead) diodes are replacing whisker contacted diodes throughout this frequency range, the handling and placement of such small GaAs chips limits performance and greatly increases component costs. Through the use of a novel wafer bonding process we have fabricated and tested submillimeter-wave components where the GaAs diode is integrated on a quartz substrate along with other circuit elements such as filters, probes and bias lines. This not only eliminates the cost of handling microscopically small chips, but also improves circuit performance. This is because the parasitic capacitance is reduced by the elimination of the GaAs substrate and the electrical embedding impedance seen by the diodes is more precisely controlled. Our wafer bonding process has been demonstrated through the fabrication and testing of a fundamental mixer at 585 GHz (Tmix < 1200K) and a 380 GHz subharmonically pumped mixer (Tmix < 1000K). This paper reviews the wafer bonding process and discusses how it can be used to greatly improve the performance and manufacturability of submillimeter-wave components.

Heat transfer coefficients in a set of three symmetrically heated narrow gap channels arranged in line are reported at power densities of 1 kW/cm3 and wall heat flux of 3–40 W/cm2. This configuration emulates an electronics system wherein power dissipation can vary across an array of processors, memory chips, or other components. Three pairs of parallel ceramic resistance heaters in a nearly adiabatic housing form the flow passage, and length-to-gap ratios for each pair of heaters are 34 at a gap of 0.36 mm. Novec™ 7200 and 7300 are used as the heat transfer fluids. Nonuniform longitudinal power distributions are designed with the center heater pair at 1.5X and 2X the level of the first and third heater pairs. At all levels of inlet subcooling, single-phase heat transfer dominates over the first two heater pairs, while the third pair exhibits significant increases because of the presence of flow boiling. Reynolds numbers range from 250 to 1200, Weber numbers from 2 to 14, and boiling numbers from O(10−4) to O(10−3). Exit quality can reach 30% in some cases. Overall heat transfer coefficients of 40 kW/m2K are obtained. Pressure drops for both Novec™ heat transfer fluids are approximately equal at a given mass flux, and a high ratio of heat transfer to pumping power (coefficient of performance (COP)) is obtained. With a mass flux of 250 kg/m2s, heater temperatures can exceed 95 °C, which is the acceptable limit of steady operation for contemporary high performance electronics. Thus, an optimal operating point involving power density, power distribution, mass flux, and inlet subcooling is suggested by the data set for this benchmark multiheater configuration.

As the name suggests, the humanities is largely a study of the human condition, in which history sits as a discipline concerned with the past. Environmental history is a new field that brings together scholars from a range of disciplines to consider the changing relationships between humans and the environment over time. Critiques of anthropocentrism that place humans at the centre of the universe or make assessments through an exclusive human perspective provide a challenge to scholars to rethink our traditional biases against the nonhuman world. The movement towards nonhumanism or posthumanism, however, does not seem to have had much of an impression on history as a discipline. What would a nonhumanist history look like if we re-centred the historical narrative around pigs? There are histories of pigs as food (see for example, The Cambridge History of Food which has a chapter on “Hogs”). There are food histories that feature pork in terms of its relationship to multiethnic identity (such as Donna Gabaccia’s We Are What We Eat) and examples made of pigs to promote ethical eating (Singer). Pigs are central to arguments about dietary rules and what motivates them (Soler; Dolander). Ancient pig DNA has also been employed in studies on human migration and colonisation (Larson et al.; Durham University). Pigs are also widely used in a range of products that would surprise many of us. In 2008, Christien Meindertsma spent three years researching the products made from a single pig. Among some of the more unexpected results were: ammunition, medicine, photographic paper, heart valves, brakes, chewing gum, porcelain, cosmetics, cigarettes, hair conditioner and even bio diesel. Likewise, Fergus Henderson, who coined the term ‘nose to tail eating’, uses a pig on the front cover of the book of that name to suggest the extraordinary and numerous potential of pigs’ bodies. However, my intention here is not to pursue a discussion of how parts of their bodies are used, rather to consider a reorientation of the historical narrative to place pigs at the centre of stories of our co-evolution, in order to see what their history might say about humans and our relationships with them. This is underpinned by recognition of the inter-relationality of humans and animals. The relationships between wild boar and pigs with humans has been long and diverse. In a book exploring 10,000 years of interaction, Anton Ervynck and Peter Rowley-Conwy argue that pigs have been central to complex cultural developments in human societies and they played an important role in human migration patterns. The book is firmly grounded within the disciplines of zoology, anthropology and archaeology and contributes to an understanding of the complex and changing relationship humans have historically shared with wild boar and domestic pigs. Naturalist Lyall Watson also explores human/pig relationships in The Whole Hog. The insights these approaches offer for the discipline of history are valuable (although overlooked) but, more importantly, such scholarship also challenges a humanist perspective that credits humans exclusively with historical change and suggests, moreover, that we did it alone. Pigs occupy a special place in this history because of their likeness to humans, revealed in their use in transplant technology, as well as because of the iconic and paradoxical status they occupy in our lives. As Ervynck and Rowley-Conwy explain, “On the one hand, they are praised for their fecundity, their intelligence, and their ability to eat almost anything, but on the other hand, they are unfairly derided for their apparent slovenliness, unclean ways, and gluttonous behaviour” (1). Scientist Niamh O’Connell was struck by the human parallels in the complex social structures which rule the lives of pigs and people when she began a research project on pig behaviour at the Agricultural Research Institute at Hillsborough in County Down (Cassidy). According to O’Connell, pigs adopt different philosophies and lifestyle strategies to get the most out of their life. “What is interesting from a human perspective is that low-ranking animals tend to adopt one of two strategies,” she says. “You have got the animals who accept their station in life and then you have got the other ones that are continually trying to climb, and as a consequence, their life is very stressed” (qtd. in Cassidy). The closeness of pigs to humans is the justification for their use in numerous experiments. In the so-called ‘pig test’, code named ‘Priscilla’, for instance, over 700 pigs dressed in military uniforms were used to study the effects of nuclear testing at the Nevada (USA) test site in the 1950s. In When Species Meet, Donna Haraway draws attention to the ambiguities and contradictions promoted by the divide between animals and humans, and between nature and culture. There is an ethical and critical dimension to this critique of human exceptionalism—the view that “humanity alone is not [connected to the] spatial and temporal web of interspecies dependencies” (11). There is also that danger that any examination of our interdependencies may just satisfy a humanist preoccupation with self-reflection and self-reproduction. Given that pigs cannot speak, will they just become the raw material to reproduce the world in human’s own image? As Haraway explains: “Productionism is about man the tool-maker and -user, whose highest technical production is himself […] Blinded by the sun, in thrall to the father, reproduced in the sacred image of the same, his rewards is that he is self-born, an auto telic copy. That is the mythos of enlightenment and transcendence” (67). Jared Diamond acknowledges the mutualistic relationship between pigs and humans in Guns, Germs and Steel and the complex co-evolutionary path between humans and domesticated animals but his account is human-centric. Human’s relationships with pigs helped to shape human history and power relations and they spread across the world with human expansion. But questioning their utility as food and their enslavement to this cause was not part of the account. Pigs have no voice in the histories we write of them and so they can appear as passive objects in their own pasts. Traces of their pasts are available in humanity’s use of them in, for example, the sties built for them and the cooking implements used to prepare meals from them. Relics include bones and viruses, DNA sequences and land use patterns. Historians are used to dealing with subjects that cannot speak back, but they have usually left ample evidence of what they have said. In the process of writing, historians attempt to perform the miracle, as Curthoys and Docker have suggested, of restoration; bringing the people and places that existed in the past back to life (7). Writing about pigs should also attempt to bring the animal to life, to understand not just their past but also our own culture. In putting forward the idea of an alternative history that starts with pigs, I am aware of both the limits to such a proposal, and that most people’s only contact with pigs is through the meat they buy at the supermarket. Calls for a ban on intensive pig farming (RSPCA, ABC, AACT) might indeed have shocked people who imagine their dinner comes from the type of family farm featured in the movie Babe. Baby pigs in factory farms would have been killed a long time before the film’s sheep dog show (usually at 3 to 4 months of age). In fact, because baby pigs do grow so fast, 48 different pigs were used to film the role of the central character in Babe. While Babe himself may not have been aware of the relationship pigs generally have to humans, the other animals were very cognisant of their function. People eat pigs, even if they change the name of the form it takes in order to do so:Cat: You know, I probably shouldn’t say this, but I’m not sure if you realize how much the other animals are laughing at you for this sheep dog business. Babe: Why would they do that? Cat: Well, they say that you’ve forgotten that you’re a pig. Isn't that silly? Babe: What do you mean? Cat: You know, why pigs are here. Babe: Why are any of us here? Cat: Well, the cow’s here to be milked, the dogs are here to help the Boss's husband with the sheep, and I’m here to be beautiful and affectionate to the boss. Babe: Yes? Cat: [sighs softly] The fact is that pigs don’t have a purpose, just like ducks don’t have a purpose. Babe: [confused] Uh, I—I don’t, uh ... Cat: Alright, for your own sake, I’ll be blunt. Why do the Bosses keep ducks? To eat them. So why do the Bosses keep a pig? The fact is that animals don’t seem to have a purpose really do have a purpose. The Bosses have to eat. It’s probably the most noble purpose of all, when you come to think about it. Babe: They eat pigs? Cat: Pork, they call it—or bacon. They only call them pigs when they’re alive (Noonan). Babe’s transformation into a working pig to round up the sheep makes him more useful. Ferdinand the duck tried to do the same thing by crowing but was replaced by an alarm clock. This is a common theme in children’s stories, recalling Charlotte’s campaign to praise Wilbur the pig in order to persuade the farmer to let him live in E. B. White’s much loved children’s novel, Charlotte’s Web. Wilbur is “some pig”, “terrific”, “radiant” and “humble”. In 1948, four years before Charlotte’s Web, White had published an essay “Death of a Pig”, in which he fails to save a sick pig that he had bought in order to fatten up and butcher. Babe tried to present an alternative reality from a pig’s perspective, but the little pig was only spared because he was more useful alive than dead. We could all ask the question why are any of us here, but humans do not have to contemplate being eaten to justify their existence. The reputation pigs have for being filthy animals encourages distaste. In another movie, Pulp Fiction, Vincent opts for flavour, but Jules’ denial of pig’s personalities condemns them to insignificance:Vincent: Want some bacon? Jules: No man, I don’t eat pork. Vincent: Are you Jewish? Jules: Nah, I ain’t Jewish, I just don’t dig on swine, that’s all. Vincent: Why not? Jules: Pigs are filthy animals. I don’t eat filthy animals. Vincent: Bacon tastes gooood. Pork chops taste gooood. Jules: Hey, sewer rat may taste like pumpkin pie, but I’d never know ’cause I wouldn’t eat the filthy motherfucker. Pigs sleep and root in shit. That’s a filthy animal. I ain’t eat nothin’ that ain’t got sense enough to disregard its own feces [sic]. Vincent: How about a dog? Dogs eats its own feces. Jules: I don’t eat dog either. Vincent: Yeah, but do you consider a dog to be a filthy animal? Jules: I wouldn’t go so far as to call a dog filthy but they’re definitely dirty. But, a dog’s got personality. Personality goes a long way. Vincent: Ah, so by that rationale, if a pig had a better personality, he would cease to be a filthy animal. Is that true? Jules: Well we’d have to be talkin’ about one charming motherfuckin’ pig. I mean he’d have to be ten times more charmin’ than that Arnold on Green Acres, you know what I’m sayin’? In the 1960s television show Green Acres, Arnold was an exceptional pig who was allowed to do whatever he wanted. He was talented enough to write his own name and play the piano and his attempts at painting earned him the nickname “Porky Picasso”. These talents reflected values that are appreciated, and so he was. The term “pig” is, however, chiefly used a term of abuse, however, embodying traits we abhor—gluttony, obstinence, squealing, foraging, rooting, wallowing. Making a pig of yourself is rarely honoured. Making a pig of the humanities, however, could be a different story. As a historian I love to forage, although I use white gloves rather than a snout. I have rubbed my face and body on tree trunks in the service of forestry history and when the temperature rises I also enjoy wallowing, rolling from side to side rather than drawing a conclusion. More than this, however, pigs provide a valid means of understanding key historical transitions that define modern society. Significant themes in modern history—production, religion, the body, science, power, the national state, colonialism, gender, consumption, migration, memory—can all be understood through a history of our relationships with pigs. Pigs play an important role in everyday life, but their relationship to the economic, social, political and cultural matters discussed in general history texts—industrialisation, the growth of nation states, colonialism, feminism and so on—are generally ignored. However “natural” this place of pigs may seem, culture and tradition profoundly shape their history and their own contribution to those forces has been largely absent in history. What, then, would the contours of such a history that considered the intermeshing of humans and pigs look like? The intermeshing of pigs in early human history Agricultural economies based on domestic animals began independently in different parts of the world, facilitating increases in population and migration. Evidence for long-term genetic continuity between modern and ancient Chinese domestic pigs has been established by DNA sequences. Larson et al. have made an argument for five additional independent domestications of indigenous wild boar populations: in India, South East Asia and Taiwan, which they use to develop a picture of both pig evolution and the development and spread of early farmers in the Far East. Domestication itself involves transformation into something useful to animals. In the process, humans became transformed. The importance of the Fertile Crescent in human history has been well established. The area is attributed as the site for a series of developments that have defined human history—urbanisation, writing, empires, and civilisation. Those developments have been supported by innovations in food production and animal husbandry. Pig, goats, sheep and cows were all domesticated very early in the Fertile Crescent and remain four of the world’s most important domesticated mammals (Diamond 141). Another study of ancient pig DNA has concluded that the earliest domesticated pigs in Europe, believed to be descended from European wild boar, were introduced from the Middle East. The research, by archaeologists at Durham University, sheds new light on the colonisation of Europe by early farmers, who brought their animals with them. Keith Dobney explains:Many archaeologists believe that farming spread through the diffusion of ideas and cultural exchange, not with the direct migration of people. However, the discovery and analysis of ancient Middle Eastern pig remains across Europe reveals that although cultural exchange did happen, Europe was definitely colonised by Middle Eastern farmers. A combination of rising population and possible climate change in the ‘fertile crescent’, which put pressure on land and resources, made them look for new places to settle, plant their crops and breed their animals and so they rapidly spread west into Europe (ctd in ScienceDaily). Middle Eastern farmers colonised Europe with pigs and in the process transformed human history. Identity as a porcine theme Religious restrictions on the consumption of pigs come from the same area. Such restrictions exist in Jewish dietary laws (Kashrut) and in Muslim dietary laws (Halal). The basis of dietary laws has been the subject of much scholarship (Soler). Economic and health and hygiene factors have been used to explain the development of dietary laws historically. The significance of dietary laws, however, and the importance attached to them can be related to other purposes in defining and expressing religious and cultural identity. Dietary laws and their observance may have been an important factor in sustaining Jewish identity despite the dispersal of Jews in foreign lands since biblical times. In those situations, where a person eats in the home of someone who does not keep kosher, the lack of knowledge about your host’s ingredients and the food preparation techniques make it very difficult to keep kosher. Dietary laws require a certain amount of discipline and self-control, and the ability to make distinctions between right and wrong, good and evil, pure and defiled, the sacred and the profane, in everyday life, thus elevating eating into a religious act. Alternatively, people who eat anything are often subject to moral judgments that may also lead to social stigmatisation and discrimination. One of the most powerful and persuasive discourses influencing current thinking about health and bodies is the construction of an ‘obesity epidemic’, critiqued by a range of authors (see for example, Wright & Harwood). As omnivores who appear indiscriminate when it comes to food, pigs provide an image of uncontrolled eating, made visible by the body as a “virtual confessor”, to use Elizabeth Grosz’s term. In Fat Pig, a production by the Sydney Theatre Company in 2006, women are reduced to being either fat pigs or shrieking shallow women. Fatuosity, a blog by PhD student Jackie Wykes drawing on her research on fat and sexual subjectivity, provides a review of the play to describe the misogyny involved: “It leaves no options for women—you can either be a lovely person but a fat pig who will end up alone; or you can be a shrill bitch but beautiful, and end up with an equally obnoxious and shallow male counterpart”. The elision of the divide between women and pigs enacted by such imagery also creates openings for new modes of analysis and new practices of intervention that further challenge humanist histories. Such interventions need to make visible other power relations embedded in assumptions about identity politics. Following the lead of feminists and postcolonial theorists who have challenged the binary oppositions central to western ideology and hierarchical power relations, critical animal theorists have also called into question the essentialist and dualist assumptions underpinning our views of animals (Best). A pig history of the humanities might restore the central role that pigs have played in human history and evolution, beyond their exploitation as food. Humans have constructed their story of the nature of pigs to suit themselves in terms that are specieist, racist, patriarchal and colonialist, and failed to grasp the connections between the oppression of humans and other animals. The past and the ways it is constructed through history reflect and shape contemporary conditions. In this sense, the past has a powerful impact on the present, and the way this is re-told, therefore, also needs to be situated, historicised and problematicised. The examination of history and society from the standpoint of (nonhuman) animals offers new insights on our relationships in the past, but it might also provide an alternative history that restores their agency and contributes to a different kind of future. 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