Academic literature on the topic 'Release Retarding'
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Journal articles on the topic "Release Retarding"
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Bhoite, Sangram P., Jonghyuck Kim, Wan Jo, et al. "Understanding the Influence of Gypsum upon a Hybrid Flame Retardant Coating on Expanded Polystyrene Beads." Polymers 14, no. 17 (2022): 3570. http://dx.doi.org/10.3390/polym14173570.
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A low-cost and effective flame retarding expanded polystyrene (EPS) foam was prepared herein by using a hybrid flame retardant (HFR) system, and the influence of gypsum was studied. The surface morphology and flame retardant properties of the synthesized flame retardant EPS were characterized using scanning electron microscopy (SEM) and cone calorimetry testing (CCT). The SEM micrographs revealed the uniform coating of the gypsum-based HFR on the EPS microspheres. The CCT and thermal conductivity study demonstrated that the incorporation of gypsum greatly decreases the peak heat release rate (PHRR) and total heat release (THR) of the flame retarding EPS samples with acceptable thermal insulation performance. The EPS/HFR with a uniform coating and the optimum amount of gypsum provides excellent flame retardant performance, with a THR of 8 MJ/m2, a PHRR of 53.1 kW/m2, and a fire growth rate (FIGRA) of 1682.95 W/m2s. However, an excessive amount of gypsum weakens the flame retardant performance. The CCT results demonstrate that a moderate gypsum content in the EPS/HFR sample provides appropriate flame retarding properties to meet the fire safety standards.
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Srivastava, Anoop Kumar, Dharmedra Singh Rajput, Naveen Gupta, and Neeraj K Sharma. "Formulation and Evaluation of Nicorandil Floating Tablets Using Natural Polymers." Asian Journal of Pharmaceutical Research and Development 11, no. 2 (2023): 74–82. http://dx.doi.org/10.22270/ajprd.v11i2.1250.
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The present work described the pre-formulation and formulation development that led to the production of Nicorandil (NDL) floating tablets by direct compression of a homogeneous powder blend/ granules. In order to achieve the drug (NDL) release up to 24 hrs, rafting approach was selected. Studies have been carried out on rafting method by the use of natural polymers (sodium alginate, xanthan gum and guar gum) alone and their combination to get maximum rafting properties with superior drug release retarding activity. The results obtained in the rafting approach indicated that the polymer combination showed significant influence on rafting properties with maximum drug release retarding ability than individual polymers. In addition, the polymer combination of xanthan gum and guar gum resulted with maximum drug release retarding ability with poor rafting properties, whereas, the polymer combination of sodium alginate and guar gum resulted with predictable release behaviour (i.e. slightly lower retarding ability than the combination of xanthan gum and guar gum) with maximum rafting properties. As such the floating tablets prepared with rafting approach were recommended for oral controlled delivery of NDL.
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Bhoite, Sangram P., Jonghyuck Kim, Wan Jo, et al. "Expanded Polystyrene Beads Coated with Intumescent Flame Retardant Material to Achieve Fire Safety Standards." Polymers 13, no. 16 (2021): 2662. http://dx.doi.org/10.3390/polym13162662.
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The compatibility and coating ratio between flame retardant materials and expanded polystyrene (EPS) foam is a major impediment to achieving satisfactory flame retardant performance. In this study, we prepared a water-based intumescent flame retardant system and methylene diphenyl diisocyanate (MDI)-coated expandable polystyrene microspheres by a simple coating approach. We investigated the compatibility, coating ratio, and fire performance of EPS- and MDI-coated EPS foam using a water-based intumescent flame retardant system. The microscopic study revealed that the water-based intumescent flame retardant materials were successfully incorporated with and without MDI-coated EPS microspheres. The cone calorimeter tests (CCTs) of the MDI-coated EPS containing water-based intumescent flame retardant materials exhibited better flame retardant performance with a lower total heat release (THR) 7.3 MJ/m2, peak heat release rate (PHRR) 57.6 kW/m2, fire growth rate (FIGRA) 2027.067 W/m2.s, and total smoke production (TSP) 0.133 m2. Our results demonstrated that the MDI-coated EPS containing water-based intumescent flame retardant materials achieved flame retarding properties as per fire safety standards.
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Jacob, Leena, Abhilash Tv, and Shajan Abraham. "FORMULATION AND EVALUATION OF PERINDOPRIL MICROENCAPSULES BY USING DIFFERENT POLYMER." Asian Journal of Pharmaceutical and Clinical Research 10, no. 2 (2017): 153. http://dx.doi.org/10.22159/ajpcr.2017.v10i2.14899.
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Objective: The study was carried out with an objective to achieve a potential sustained release oral drug delivery system of an antihypertensive drug, Perindopril which is a ACE inhibitor having half life of 2 hours. Perindopril is water soluble drug, so we can control or delay the release rate of drug by using release retarding polymers. This may also decrease the toxic side effects by preventing the high initial concentration in the blood.Method: Microcapsules were prepared by solvent evaporation technique using Eudragit L100 and Ethyl cellulose as a retarding agent to control the release rate and magnesium stearate as an inert dispersing carrier to decrease the interfacial tension between lipophilic and hydrophilic phase. Results: Prepared microcapsules were evaluated for the particle size, percentage yield, drug entrapment efficiency, flow property and in vitro drug release for 12 h. Results indicated that the percentage yield, mean particle size, drug entrapment efficiency and the micrometric properties of the microcapsules was influenced by various drug: polymer ratio. The release rate of microcapsules could be controlled as desired by adjusting the combination ratio of dispersing agents to retarding agents.Conclusion:Perindopril microcapsules can be successfully designed to develop sustained drug delivery, that reduces the dosing frequency and their by one can increase the patient compliance.
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Bhusara, Hiral S., Ara T. Patel, and Mayuree D. Patel. "Development of gastroretentiv floating tablets of losartan potassium by sublimation method." International Journal of Pharmaceutical Chemistry and Analysis 8, no. 2 (2021): 66–74. http://dx.doi.org/10.18231/j.ijpca.2021.014.
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The purpose of present study was to formulate and Evaluate Sustained release floating tablet of losartan Potassium using Camphor and Polyethylene Oxide as Pore formation for floating and release retarding agent respectively to improve gastric residence time and patient compliance in management of hypertension. The tablet was prepared by direct compression by using HPMC K4 as dry binder. Camphor and PEO as floating and release retarding agent for sustained release floating tablet. Post compression was done to increase the hardness and floating time of tablet. Release modifier was used to speed up the release of drug from sustained release floating tablet. The effect of two independent variables like amount of Sublimating agent (camphor) and amount of Polyethylene oxide (PEO) on Q30min, Q360min, and Q720min was optimized using 32 factorial design and analyzed using the software design expert 10.0.3. The observed (actual values) responses were coincided well with the predicted values, given by the optimization technique. The floating tablet were characterized by FTIR for drug excipient compatibility.
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Wang, Yachao, and Jiangping Zhao. "Ecological Ammonium Thiocyanate-Modified Geopolymeric Coating for Flame-Retarding Plywood." Coatings 9, no. 8 (2019): 479. http://dx.doi.org/10.3390/coatings9080479.
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An ecological ammonium thiocyanate (NH4SCN)-modified geopolymeric coating was facilely prepared for flame-retarding plywood. The effect of NH4SCN on the flame resistance was preliminarily investigated using cone calorimeter (CC), scanning electron microscope (SEM), X-ray diffraction (XRD), and thermal gravimetry (TG). The results show that 1 wt.% NH4SCN as dopant is of paramount importance to generate a compact and continuous coating. The formation of a smooth, intact, and uniform-swelling siliceous layer during combustion facilitates enhanced fire resistance, evidenced by the increased fire performance index (FPI), reduced fire growth index (FGI), and 39.7% decreased value of peak heat release rate (pHRR), in comparison to those of the sample without NH4SCN. Because of the reducibility of O2-consuming NH4SCN, the compact shielding-layer containing carbonate and sulfate, as well as the release of NH3, the NH4SCN-modified geopolymeric coating exerts an enhancement on the flame-retardant efficiency.
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Simran, Tanwar, Tikariya Komal, and Sharma Vimukta. "Formulation and Evaluation of Sustained Release Matrix Tablet of Nimesulide Using Pomegranate Peel and Acacia." International Journal of Pharmaceutical Sciences and Medicine 7, no. 7 (2022): 11–24. http://dx.doi.org/10.47760/ijpsm.2022.v07i07.002.
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The main objective of the study is the formulation and evaluation of sustained release matrix tablet of Nimesulide using pomegranate peel and acacia as natural polymer. The preformulation study of Nimesulide was conducted and λmax was found at 300 nm. The sustained release matrix tablet was prepared using Pomegranate peel as Release rate retardant, Acacia as polymer, Polyvinylpyrrolidone K30 as Binder, Isopropyl alcohol as Granulation solution, Micro Crystalline Cellulose as Diluent, Magnesium stearate as Lubricant and Talc as Glidant. Several formulations were prepared by taking different drug concentration in Pomegranate peel (Release rate retardant) with varying ratio of binder to lubricants. Various formulations of sustained release matrix tablet of Nimesulide F1, F2, F3, F4, F5, F6 was prepared. The prepared granules were evaluated for different parameters like Bulk density, Tapped density, Angle of repose, Carr’s index, Hausner’s ratio which shows the excellent flow properties of formulation. The physical characteristic of Nimesulide sustained release matrix tablets (F1 to F6) such as thickness, diameter, hardness, friability, weight variation and drug content were determined and results of the formulations (F1 to F6) found to be within the limits specified in official books. The drug content of all the formulation were found to be in the range of 99.59 to 99.83 % w/w, which is within the specified limit as per Indian Pharmacopoeia 1996 (i.e. 90-110% w/w). The drug released from formulation F1 to F3 was found to be 93.7, 92.9 and 92.2 % for Nimesulide respectively. The drug released from formulation F4 to F6 was found to be 94.1, 93.9 and 92.8% for Nimesulide respectively. The release rate of F1 and F4 was found to be higher when compared to other formulations this is due to increase in the concentration of polymer. These results are indicating that has higher drug retarding ability for long duration. All the formulations were analyzed for stability testing. All the formulations from F1 to F6 were found to be stable.
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Cheng, Bing-Ming, J. R. Grover, E. A. Walters, and J. T. Clay. "Kinetic energy release distributions from dissociative photoionization of weakly bound trimers at 14–27 eV." Physical Chemistry Chemical Physics 20, no. 32 (2018): 21034–42. http://dx.doi.org/10.1039/c8cp03013h.
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Lü, Shaoyu, Chunmei Gao, Xinggang Wang, et al. "Synthesis of a starch derivative and its application in fertilizer for slow nutrient release and water-holding." RSC Adv. 4, no. 93 (2014): 51208–14. http://dx.doi.org/10.1039/c4ra06006g.
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Gholap, Apoorv Nitin, Dr Pranav Parekh, Dr Mrunal Shirsat, Vaibhav Narwade, and Gokul Mali. "Formulation and Evaluation of Sustained Release Matrix Tablet of Quinapril by Using Natural Polymers." International Journal for Research in Applied Science and Engineering Technology 13, no. 4 (2025): 5533–42. https://doi.org/10.22214/ijraset.2025.69586.
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Abstract: In present investigation an attempt has been made to design and develop some Quinapril matrix tablets using KarayaGum, Guar gum, KollidonSRas release retarding polymers. Quinapril is Anti-hypertensive drug which lowers blood pressure level and has been selected to prepare sustained release dosage forms. Quinapril sustained release matrix tablets were prepared using KarayaGum, Guar gum, KollidonSR as base polymer by wet granulation method. FTIR spectral analysis showed that characteristic peak of Quinapril pure drug was retained in the spectra of all the formulations indicating the intactness of the drug in all the formulations. Quinapril matrix tablets formulated employing Kollidon SR and combination of Karaya Gum and Guar gum provided slow and controlled release of Quinapril up to 24 hr. All the tablet formulation showed compliance with pharmacopoeia standard as the time increases. The dissolution result shows that an increased amount of polymer resulted in reduced drug release. A concentration dependent drug release is evident in case of the polymer i.e., lower concentration of polymers, release is marginally retarded at higher concentration is considerable. Prepared sustained formulation containing KarayaGum, Guar gum, KollidonSR as release retarding polymers (F6) probably showing better release based up to 98% drug release within 24 hours.
Dissertations / Theses on the topic "Release Retarding"
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Assali, Mirella Pennacchi. "Emprego de agentes retardadores em substituição aos desmoldantes convencionais na moldagem de concreto para recebimento do revestimento de argamassas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-18072013-154420/.
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As estruturas de concreto são moldadas em formas tratadas com desmoldantes e sua presença dificulta a adesão da argamassa fresca, com posterior descolamento no estado endurecido. Este estudo tem por objetivo explorar o potencial de uso de agentes retardadores em substituição aos desmoldantes convencionais na moldagem de concreto para obtenção de superfícies com maior capacidade de ancoragem das argamassas. A viabilidade do uso de agentes retardadores foi verificada determinando-se de modo comparativo a resistência de aderência à tração da argamassa e do chapisco aplicados sobre corpos de prova de concreto moldados em formas de madeira plastificada tratadas com agente retardador e com desmoldante convencional. O ensaio de aderência mostrou que a utilização de agentes retardadores possibilita maior facilidade para a remoção da camada superficial do concreto, resultando em aumento de rugosidade e absorção superficial, permitindo maior resistência de aderência da argamassa e chapisco. Posteriormente, foram coletados agentes retardadores do mercado e avaliados: desempenho na aplicação sobre as formas, impacto dos produtos na saúde do trabalhador e no meio ambiente, e o efeito retardador na hidratação do cimento. Também foram avaliados quanto: a aplicabilidade dos produtos e sua influência no preparo da superfície para o recebimento da argamassa quando tratadas com produtos retardadores e convencionais em três tipos de formas. O estudo mostrou que o uso de agente retardador pode ser uma técnica viável para reduzir os problemas de descolamento do revestimento aplicado sobre superfícies de concreto. Através dos ensaios específicos desenvolvidos e adaptados para esta pesquisa, foi possível identificar que existem diferenças de comportamentos entre os produtos, sendo eles convencionais ou retardadores, e que os tipos de forma influenciam nestes comportamentos. Foi verificado também que as formas mais simples e com custos menores podem ser mais apropriadas para utilização destes produtos.<br>The concrete structures are cast in molds treated with a release agent (demolding product), and its presence hinders the mortars initial adhesion in the plastic state, as well as the bond strength after hardening. The study aims is to explore the potential use of retarding agents to replace conventional release agents in the concrete formwork. The technical viability of using a retarding agent was verified by comparing the tensile bond strength of rendering mortars applied on concrete surfaces cast with a conventional release agent and on concrete surfaces cast with a retarding release agent. The results showed that, through the use of retarding products, the removal of the concrete surface layer was possible by increasing the surface roughness, the surface water absorption and the tensile bond strength of the mortar to this concrete. Performance tests were also done with retarding products commercially available in the Brazilian market to verify the behavior of such products during application on molds, their impact on workers health and on the environment, and the retarding effect in cement hydration. It was also evaluated the applicability of these products and their influence on surface preparation to receive mortar when treated with retarding and conventional products, in three types of molds. Retarding products showed to be a viable technique for reducing the detachment problems of rendering mortars applied on concrete surfaces. Through the specific tests developed and adapted for this study, it was observed that there are differences in behavior between the conventional or retarding products, and also observed how these types of molds can influence the performance of the products. It was also observed that the simplest molds with lower cost can be more suitable in this application.
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Dogra, Sanjeev. "A Chitosan–Polymer Hydrogel Bead System For A Metformin HCl Controlled Release Oral Dosage Form." University of Toledo Health Science Campus / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=mco1303179716.
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Nemura, Adrienne Denise. "Effectiveness of weirs on the New River in retarding rapid releases from Claytor Lake Dam at Big Falls." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101138.
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Reservoir releases for power generation often cause rapidly fluctuating water levels and increased velocities in certain downstream sections of rivers. These conditions and the natural geometry of the river can render certain sections of the river dangerous for recreation. Although public utilities take precautionary safety measures immediately downstream of the dam, their measures further downstream have been limited, if not non-existent. The placement of weirs between the dam and dangerous sections would retard the flow—slowing the rise in water levels and decreasing velocities at predetermined dangerous sections.
Big Falls, on the New River near McCoy, Virginia, is a popular recreation spot and becomes dangerous at certain times of the day due to releases from Claytor Lake Dam. Several people have drowned at this location over the years. In this study, the influence of weirs placed upstream of Big Falls on the rise of water level and increase in velocity is investigated by an implicit finite difference computer model of one-dimensional gradually varied unsteady flow.
The model allows for investigation of different weir geometries and placements, and the effectiveness of these weirs when subjected to various boundary conditions which arise from variations of the maximum peak release hydrograph from Claytor Lake Dam from May to September of 1983 and 1984.
Results of the study consist of the optimum weir geometry and placement on the New River upstream of Big Falls. Criteria for determining the weir included physical location limitations, and the effectiveness of the weir in reducing the rate-of-rise of water levels and increased velocities at Big Falls.<br>M.S.
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Saleem, Saima. "A method of chemical aftertreatment for the reduction of free formaldehyde release of a durable flame retardant finished cotton fabric." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-360.
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This thesis aims at developing a method of chemical aftertreatment for reduction of free formaldehyde release of a tetrakis (hydroxymethyl) phosphonium chloride (THPC) urea precondensate, ammonia cured durable flame retardant finished cotton fabric, by preventing the formation of free formaldehyde. Formaldehyde is toxic and carcinogenic. According to the worldwide standards, acceptable limit of free formaldehyde release, for the fabrics that have skin contact, is only 75 ppm (measured by water extraction method). In this research, a cotton fabric flame retardant finished in an industrial plant in Pakistan is used. Fabric is finished by the application of THPC urea precondensate and ammonia cured, oxidized and washed. After finishing, it is not aftertreated with sodium metabisulfite that is a commonly used aftertreatment method for the reduction of free formaldehyde release. Aftertreatment with sodium metabisulfite has various problems that include large number of hot washings and there is an increase in the formaldehyde release during fabric storage. If the fabric has 75 ppm of free formaldehyde, there is often an increase in free formaldehyde release during fabric storage. There is a very limited research on the aftertreatment methods and few reports of application of these aftertreatments on flame retardant fabrics have been published. In this research, two methods of aftertreatments are developed to reduce the free formaldehyde contents to 75 ppm or less. One is the aftertreatment with a combination of resorcinol 1% and diethylene glycol 4%. The other is the combination of resorcinol 1% and boric acid 6%. For both these aftertreatments, ammonium acetate 0.5% is used as a catalyst. Fabric is padded with the solution and then dried at 130̊ C for 8 minutes. After drying, fabric is rinsed with water at 40̊ C. The aftertreatment methods developed in this research have shown a long term effect in keeping the formaldehyde release below 75 ppm during fabric storage that is not available with other conventional aftertreatment methods. These aftertreatment methods have no adverse effect on the flame retardancy of the THPC ammonia cured finished fabric and the fabric is soft as compared to the original flame retardant finished fabric and to the fabric after treated with existing methods. These new developed methods have industrial application because there is no use of any solvent and there is no use of any special equipment for the aftertreatment.
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Tsantaridis, Lazaros. "Reaction to fire performance of wood and other building products." Doctoral thesis, KTH, Civil and Architectural Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3479.
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<p>The theme of this thesis is the reaction to fire performanceof wood and other building products, andparticularly thematerial fire properties time to ignition, rate of heat releaseand smoke production. These properties have been measured by asmall-scale fire test method, the Cone Calorimeter, andpresented for different types of building products.</p><p>Uncertainty analysis, included instrument and assumptionuncertainty, has been performed for the case that both O2 andCO2 are measured for calculation of the rate of heat release inthe Cone Calorimeter. The partial derivatives for theuncertainty analysis are given. The relative uncertainty forthe rate of heat release measurements in the Cone Calorimeteris between ±5% to ±10% for rate of heat releasevalues larger than about 50 kW/m2.</p><p>The time to ignition in the Cone Calorimeter is compatiblewith the time to ignition in the ISO Ignitability test, whichis the main test method for measuring time to ignition. Thetime to ignition is an increasing linear function of density.The rate of heat release in the Cone Calorimeter is dependentof material thickness and of use of retainer frame. Thematerial thickness gives the heat release curve duration andshape. Thin materials have short burning time and two maximumvalues. Thick materials have long burning time and when thematerial is thicker than about 35 mm no second maximum appears.When the retainer frame is used the actual exposed surface isreduced from 0.01 m2 to 0.0088 m2, the rate of heat release isreduced and the burning time is increased. A comparison ofresults with and without use of the retainer frame gives thenequal results when the exposed area is set to 0.0088 m2 in thecase of using the retainer frame.</p><p>The time to flashover in the full-scale room corner test waspredicted on the basis of Cone Calorimeter data at 50 kW/m2 bya power law of ignition time, the total heat release calculatedover 300 s after ignition and the density of the product. Therelation gives a simple relation to evaluate if a productreaches flashover in the room corner test.</p><p>The smoke production has also been measured in the ConeCalorimeter. The white light and the laser smoke measurementsystems have shown similar results. There is a correlationbetween Cone Calorimeter and room corner test smoke productionwhen the products are divided into groups: those that reachflashover in the room corner test in less than 10 min and thosethat have more than 10 min to flashover. Temperature profilesin wood have been measured in the Cone Calorimeter by a simpletechnique. The effect of fire protective gypsum plasterboardson the charring of wood frame members has been determined andcompared with fullscale furnace wall tests. The protectiveeffects of twenty different boards have been presented. ConeCalorimeter and furnace tests show similar charring of wooduntil the boards fall down in furnace tests. After that, thecharring of wood is higher in the furnace, because the wood isexposed directly to the fire.</p><p><b>Keywords:</b>building products, charring of wood, ConeCalorimeter, fire retardant treated wood, fire tests,ignitability, mass loss, rate of heat release, reaction tofire, smoke production, wood products</p>
Books on the topic "Release Retarding"
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Al-Ahmed, Amir, ed. Advanced Applications of Micro and Nano Clay. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901915.
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Due to their characteristic properties, biodegradable nature and non-toxicity, clay-biopolymer based composites have many applications in such advanced fields as drug release, antimicrobial activities, wound healing, tissue engineering, wastewater treatment, food packaging and flame retardant materials. The book reviews fabrication, properties and applications of a great variety of these materials.
Book chapters on the topic "Release Retarding"
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Gunnam, Sailaja, Monika Nijhawan, and Rajeswari Aleti. "Applicability of a New Modified Calcium Starch as Release Retarding Polymer: A Comparative Study." In Novel Aspects on Pharmaceutical Research Vol. 6. B P International (a part of SCIENCEDOMAIN International), 2023. http://dx.doi.org/10.9734/bpi/napr/v6/10660f.
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G, Patel Hiral, Pastagia Jayesh J, Senjaliya Tushar M, and Chaudhary Lala S. "ROLE OF PLANT TRICHOMES IN PEST MANAGEMENT." In Futuristic Trends in Agriculture Engineering & Food Sciences Volume 3 Book 18. Iterative International Publisher, Selfypage Developers Pvt Ltd, 2024. http://dx.doi.org/10.58532/v3bcag18p4ch1.
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Natural hair like structures, produced on aerial surfaces of plants that involves in plant defence, are recognised as trichomes. These trichomes play their role in natural plant defence. These trichomes may be glandular or non-glandular, and secrete exudates, which trap insects and slowdown their movement and act as a physical barrier either against insect attack killing the insects directly or through retarding the insect growth and their population. These trichomes play an important role against both biotic and abiotic stresses. Plant trichomes, specialized epidermal outgrowths found on the surfaces of various plant species, have gained significant attention in recent years due to their diverse roles in plant development, defense, and pest management. Trichomes serve as a physical barrier against herbivores, play a crucial role in the release of chemical deterrents, and act as key components of indirect defense mechanisms. This review aims to provide a comprehensive overview of the multifaceted contributions of plant trichomes in pest management, focusing on their structural characteristics, chemical defense, and ecological interactions with herbivores. Understanding the mechanisms underlying the role of trichomes in pest management can potentially pave the way for the development of novel strategies for sustainable agriculture.
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Daniela Lopes, Ana, Maria Graciela Iecher Faria Nunes, João Paulo Francisco, and Eveline Henrique dos Santos. "Potential Allelopathic Effect of Species of the Asteraceae Family and Its Use in Agriculture." In Asteraceae - Characterization, Recent Advances and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.108709.
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Some species are capable of producing substances that affect seed germination, stimulating, or retarding this process, and can also suppress the development of other plants, acting as an antagonistic plant. This can occur naturally, through the release of exudates, or through the action of essential oil, extracts obtained from different parts of the plant, or plant residues with potential allelopathic action. The aim of this chapter is to present the main plant genera of the Asteraceae family with potential phytotoxic or allelopathic activity, with a suppressive effect on the growth of herbicide-tolerant weeds. The genus defined were Acmella, Artemisia, and Bidens, highlighting the form of use—plant extract, essential oil, or plant residues. The Asteraceae family is considered a repository of species to be explored for allelopathy with several associated secondary metabolites such as terpenes, saponins, alkaloids, alkamides, cinnamic acid derivatives, and flavonoids. In addition to these, for the genus Bidens, the presence of the acetylenic compound phenylheptatriine (PHT) is considered an important allelochemical with potent allelopathic action. The presence of this compound is associated with the cytotoxic activity of representatives of this genus, which can be a source of prospecting for new molecules to be used as bioherbicides.
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Devaraju, Subramani, Krishnamoorthy Krishnadevi, and Muthukaruppan Alagar. "Development of Halogen Free Sustainable Polybenzoxazine Matrices and Composites for Flame Retardant Applications." In Flame Retardant and Thermally Insulating Polymers. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98470.
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In recent years, with the growing concern on energy crises, the development of new products from sustainable resources have been received much greater consideration owing to the environmental concerns caused by the rapid reduction of non-renewable fossil resources. The widespread utilization of polymeric materials led to a considerable increase in fire risk in our daily life due to their flammable behavior. Hence, the flame-retardant properties of polymeric materials are considered as one of the most significant criteria to use them in wide range of industrial applications. It is well known that mostly halogenated flame retardant materials are widely used for flame retardant applications. However, they release toxic gases and corrosive smoke during combustion, and consequently they contribute to serious environmental pollution. In this connection, in the present chapter we discussed the different types of non-halogen based environmentally friendly bio-based polybenzoxazine matrices developed from renewable and sustainable bio-phenolic materials viz., cardanol, eugenol, guiacol and etc., and the composites obtained by reinforcing with varying weight percentages of flame resistant reinforcements/additives and their flame retardant properties obtained from different analytical techniques.
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Selvasudha, Nandakumar, Unnikrishnan-Meenakshi Dhanalekshmi, Sekar Krishnaraj, Yogeeswarakannan Harish Sundar, Nagarajan Sri Durga Devi, and Irisappan Sarathchandiran. "Multifunctional Clay in Pharmaceuticals." In Clay Science and Technology [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92408.
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Clay has its widespread applications in pharmaceuticals from ancient world to modern era. It is one of the excellent excipients present in the commercially available pharmaceuticals. Its use in many of dosage forms viz. in suspension, emulsion, ointments, gels, tablet and as drug delivery carrier as suspending agent, emulsifying agent, stiffening agent, binder, diluent, opacifier, and as release retardant have been explored in many studies. Variety of minerals is used as both excipient and as an active ingredient; among that kaolinite, talc, and gypsum are important. Their inertness, low toxicity, versatile physiochemical properties and cost effectiveness has increased its usage in pharma industries. Many minerals have its own pharmacological action as antacid, anti-bacterial, anti-emetic, anti- diarrheal agent and as skin protectant etc. Their unique structure which helps them to absorb material onto their layered sheets has opened a wide variety of applications in drug delivery. The understanding of surface chemistry and particle size distribution of clay minerals has led the pharmaceutical field in many directions and future perspectives.
Conference papers on the topic "Release Retarding"
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Biswal, Swadhin Sekhar, Chandan Bhogendra Jha, Ayush Kumar, et al. "Evaluation of release-retarding potential of co-processed excipients on Quetiapine fumarate sustained release tablets." In THE FOURTH SCIENTIFIC CONFERENCE FOR ELECTRICAL ENGINEERING TECHNIQUES RESEARCH (EETR2022). AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0162840.
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Wei, Liu, Wang Qing, Xu Changfeng, et al. "A Green and Environmentally Friendly Chelated Retarding Acid for Acidification of Sandstone Reservoirs." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79271.
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Abstract Matrix acidizing is the main method to relieve formation damage in sandstone reservoirs. However, many problems in conventional mud acid acidification need to be carefully considered, such as fast acid-rock reaction, short effective action time, excessive dissolution near the well zone, and the secondary sedimentations from fluorosilicic acid, aluminosilicate, calcium fluoride and other pollution of the reservoir. In this paper, a green and degradable amino acid chelating agent is investigated. This new type of sandstone chelating retarded acid system have features of chelating metal ions and slow proton release. The chelating ability of new retarder acid to calcium and iron metal ions was determined by complexometric titration. The retarding performance of chelating retarder acid were studied by core flow instrument and microscopic scanning electron microscopy. The results show that the new acid system is manifested by strong chelating ability to iron and calcium ions, low corrosion rate, good retarding performance. The permeability is increased by 225% after acidification. The results of electron microscopy scanning of the core surface before and after acidification show that the new acid solution acidification can effectively enlarge the pore-throat without generating secondary precipitations, which is a good choice for sandstone acidification practice.
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Tsoi, Marvin, Yong Tang, Ruey-Hung Chen, and Jihua Gou. "Mass Loss and Effective Thermal Conductivity of Fire Retardant Nanocomposites." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11632.
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Carbon nanofiber (CNF) papers, when incorporated onto the surface of glass fiber reinforced polyester composites, were known to enhance the fire-retarding capability by decreasing the peak heat release rate (PHRR) and slowing down the mass loss. In this experimental study, attempts were made to understand the thermal degradation mechanisms of the composites and nanocomposites. The temperature distribution within the composite substrate should be determined because the degradation rate is related to the temperature. The composite was prepared through vacuum-assisted resin transfer molding (VARTM) process. Samples of glass-polyester resin composites were investigated. Thermal conductivity data was calculated from embedded thermocouples on the composite for real-time temperature measurement. Mass loss data was collected using thermal gravimetric analysis on resin and CNF paper samples. These results should help to further understand the depth and degree of the degradation and provide an understanding of thermal properties in composites.
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Ekoto, Isaac W., William F. Colban, Paul C. Miles, et al. "UHC and CO Emissions Sources From a Light-Duty Diesel Engine Undergoing Late-Injection Low-Temperature Combustion." In ASME 2009 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/icef2009-14030.
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Low load carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions sources are examined in an optically accessible, light-duty diesel engine employing a late-injection, low-temperature combustion strategy. The study focus is to identify the cause of the rapid degradation in emissions and efficiency as injection timing is retarded. The in-cylinder progression of mixing and combustion processes is examined through ultraviolet planar laser-induced fluorescence (UV PLIF) imaging of hydrocarbon spatial distributions. Spectrally-resolved, deep-UV LIF measurements are also used to construct late-cycle spatial distributions of CO, C2, and polycyclic aromatic hydrocarbons within the clearance volume. Engine-out emissions measurements and numerical results from both detailed chemistry homogeneous reactor and multidimensional simulations complement the measurements. The measured spatial distributions show that while most fuel accumulates on the bowl-pip during high-temperature heat-release, much of it is transported into the squish-volume by the reverse squish flow. Homogeneous reactor simulations further show that expansion cooling quenches reactions, preventing the transition to high-temperature heat-release for mixtures with an equivalence ratio below 0.6. Lean squish-volume mixtures, coupled with wall heat losses, severely inhibit squish volume fuel oxidation. Further retarding injection timing exacerbates quenching, resulting in a two-fold increase in UHC emissions and a 33% increase in CO, primarily from the squish-volume.
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Yanai, Tadanori, Xiaoye Han, Graham T. Reader, Ming Zheng, and Jimi Tjong. "Preliminary Investigation of Direct Injection Neat n-Butanol in a Diesel Engine." In ASME 2013 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icef2013-19219.
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The characteristics of combustion, emissions, and thermal efficiency of a diesel engine with direct injection neat n-butanol were investigated. Tests were conducted on a single cylinder water-cooled four stroke direct injection diesel engine. The engine ran at a load of 6.5 ∼ 8.0 bar IMEP at 1500 rpm engine speed and the injection pressure was controlled to 900 bar. The intake boost pressure, injection timing and EGR rate were adjusted to investigate the engine performance. The test results showed that significantly longer ignition delays were possible when using butanol compared to diesel fuel. Butanol usage generally led to a rapid heat release in a short period, resulting in excessively high pressure rise rate. The pressure rise rate was reduced by retarding the injection timing. The butanol injection timing was limited by misfire and pressure rise rate. Thus, the ignition timing controllable window by injection timing was much narrower than that of diesel. The neat butanol combustion produced near zero soot and very low NOx emissions even at low EGR rate. The tests demonstrated that neat butanol had the potential to achieve ultra-low emissions. However, challenges related to reducing the pressure rise rate and improving the ignition controllability were identified.
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Leenders, Tom P. E., Nick Diepstraten, Cemil Bekdemir, and Jeroen A. van Oijen. "Exploring Pilot-Assisted Hydrogen High-Pressure Direct-Injection Engines by Numerical Modeling." In ASME 2024 ICE Forward Conference. American Society of Mechanical Engineers, 2024. https://doi.org/10.1115/icef2024-140005.
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Abstract Hydrogen (H2) High-Pressure Direct-Injection (HPDI) emerges as a promising combustion concept in heavy-duty engines for GHG emissions reduction through the use of a carbon-free main fuel while preserving the high efficiency of a compression ignition engine. A pilot injection of diesel is employed to act as an ignition source for the main fuel, hydrogen, both of which are directly injected into the combustion chamber. H2 HPDI measurements are conducted under various conditions. To gain insights into the details of the fuel injection and combustion processes, an adequate Computational Fluid Dynamics (CFD) simulation is desired. Modeling such a system requires that the injection properties are accurately prescribed. It is found in the literature, that substantial uncertainties exist in these parameters. This research aims to increase the understanding of H2 HPDI combustion through a numerical investigation. Both measurement and CFD simulation are processed identically, enabling a fair comparison of the apparent rate of heat release (aROHR), which is a key indicator of their combustion phenomena. Reasonable agreement is observed between CFD simulations and measurement data. The uncertainty in the main fuel injection is investigated by varying the inflow boundary conditions. Here it is observed that with the increasing injection pressure and fuel temperature, the jet is ignited earlier and more mixing-controlled combustion is observed. Additionally, a pilot separation sweep is performed, highlighting the importance of the spatial position of the pilot combustion. Retarding the pilot injection significantly suppresses the peak aROHR.
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KASUYA, Hiroki, Yoshifumi YAMAZAKI, Seiji OKAMURA, Akira IIJIMA, and Hideo SHOJI. "A Spectroscopic Analysis of a Homogeneous Charge Compression Ignition Engine." In Small Engine Technology Conference & Exposition. Society of Automotive Engineers of Japan, 2007. http://dx.doi.org/10.4271/2007-32-0038.
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<div class="section abstract"><div class="htmlview paragraph">Homogeneous Charge Compression Ignition (HCCI) combustion offers the advantages of high efficiency and low emissions of pollutants. However, ignition timing control and expansion of the stable operation region are issues remaining to be addressed in this combustion process. Detailed analyses of ignition and combustion characteristics are needed to resolve these issues. HCCI combustion of a low octane number fuel is characterized by two-stage heat release attributed to a cool flame and a hot flame, respectively. In this study, spectroscopic techniques were used to investigate the effect of exhaust gas recirculation (EGR) on ignition and combustion characteristics using a low octane number fuel, which is apt to give rise to a cool flame. The reaction mechanism of a cool flame produces formaldehyde (HCHO). Measurements were made of spontaneous light emission and absorption at wavelengths corresponding to the light emitted at the time HCHO was produced. The light emission intensity and absorbance measured with the spectroscopic techniques revealed clear differences in the cool flame magnitude depending on changes in the EGR rate. It was found that the cool flame magnitude in the HCCI combustion process varied depending on the EGR rate and thus ignition characteristics differed considerably. An investigation was also made of the respective influence on HCCI combustion of high-temperature internal EGR and low-temperature external EGR. The results indicated that external EGR was more effective for retarding the ignition timing, owing to its larger mass per unit volume than that of internal EGR.</div></div>
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Scholl, Fino, Denis Neher, Maurice Kettner, Andrés Melgar Bachiller, and Markus Klaissle. "Effects of Intake Pressure and Air-Fuel Ratio on Controlled Hot Surface Ignition Operating with Natural Gas." In JSAE/SAE 2015 Small Engine Technologies Conference & Exhibition. Society of Automotive Engineers of Japan, 2015. http://dx.doi.org/10.4271/2015-32-0721.
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<div class="section abstract"><div class="htmlview paragraph">In an effort to reduce both maintenance costs and NO<sub>x</sub> emissions of small cogeneration engines operated with natural gas, an alternative ignition system that allows stable operation at very lean homogeneous air-fuel mixtures has been developed. Combustion is induced by an electrically heated ceramic glow plug, whose temperature is controlled by an ECU. Adjusting hot surface temperature allows shifting the inflammation timing of the mixture and, therefore, the phasing of combustion in the engine cycle.</div><div class="htmlview paragraph">The main aim of this work was to determine the effect of intake pressure and air-fuel ratio on the parameters of hot surface ignition (HSI) and understand which are the factors limiting stable HSI operation in terms of cycle-by-cycle variations. Furthermore, in order to explain abnormal combustion phenomena occurring at high surface temperatures, the process of mixture inflammation and combustion was examined through a combination of numerical simulation using the ECFM-3z combustion model and engine trials employing optical probes to record combustion radiation.</div><div class="htmlview paragraph">The experiments showed that the energy consumption required to heat the surface and initiate combustion can be decreased substantially when raising intake pressure and/or advancing combustion phasing. On the other hand, when leaning the mixture or retarding combustion, the energy demand increases. It was found that the temperature control of the hot surface is most stable when heat released from combustion is relatively low and produces low combustion temperatures. When this is not the case, e.g. at lower air-fuel ratios or advanced combustion phasings, cyclic variability in heat release rate and phasing have a strong impact on surface temperature and it becomes more difficult for the HSI controller to keep hot surface temperature constant. As a result, the timing of mixture inflammation fluctuates considerably, leading to high cyclic dispersion in CA50, IMEP and p<sub>max</sub>.</div></div>
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Bohac, Stanislav V., Eric Feiler, and Ian Bradbury. "Effect of Injection Timing on Combustion, NOx, Particulate Matter and Soluble Organic Fraction Composition in a 2-Stroke Tier 0+ Locomotive Engine." In ASME 2012 Internal Combustion Engine Division Spring Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ices2012-81135.
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This study investigates how injection timing affects combustion, NOx, PM mass and composition from a 2-stroke turbocharged locomotive diesel engine fitted with an early-development Tier 0+ emissions kit. The objective of the work is to gain insight into how injection timing affects combustion and emissions in this family of engines, modified to meet the newly implemented Tier 0+ emissions requirements, and to identify areas of potential future emissions reduction. For a range of injection timings at a medium load (notch 5) operating condition, the majority of PM mass is comprised of insolubles (81–89%), while the soluble component of PM (SOF) accounts for a smaller fraction (11–19%) of total PM mass. The SOF is 66–80% oil-like C22–C30+ hydrocarbons, with the remainder being fuel-like C9–C21 hydrocarbons. A heat release analysis is used to elucidate how injection timing affects combustion by calculating mass fraction burn curves. It is observed that retarding injection timing retards combustion phasing, decreases peak cylinder pressure and temperature, and increases expansion pressure and temperature. Results show that insolubles and fuel-like hydrocarbons increase and oil-like hydrocarbons decrease with later injection timing. Analysis suggests that insolubles and fuel-like HC increase due to lower peak combustion temperature, while oil-like HC, which are distributed more widely throughout the cylinder, decrease due to higher expansion temperatures. The net result is that total PM mass increases with retarded combustion phasing, mostly due to increased insolubles. Considering the high fraction of insoluble PM (81–89%) at all injection timings tested at notch 5, steps taken to reduce PM elemental carbon should be the most effective path for future reductions in PM emissions. Further reductions in oil consumption may also reduce PM, but to a smaller extent.
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Holzberger, Sascha, Maurice Kettner, and Roland Kirchberger. "Improvement of the EGR Dilution Tolerance in Gasoline Engines by the Use of a HSASI Pre-Chamber Spark Plug." In Small Powertrains and Energy Systems Technology Conference. SAE International, 2023. http://dx.doi.org/10.4271/2023-01-1805.
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<div class="section abstract"><div class="htmlview paragraph">Charge dilution in gasoline engines reduces NO<sub>x</sub> emissions and wall heat losses by the lower combustion temperature. Furthermore, under part load conditions de-throttling allows the reduction of pumping losses and thus higher engine efficiency. In contrast to lean burn, charge dilution by exhaust gas recirculation (EGR) under stoichiometric combustion conditions enables the use of an effective three-way catalyst. A pre-chamber spark plug with hot surface-assisted spark ignition (HSASI) was developed at the UAS Karlsruhe to overcome the drawbacks of charge dilution, especially under part load or cold start conditions, such as inhibited ignition and slow flame speed, and to even enable a further increase of the dilution rate. The influence of the HSASI pre-chamber spark plug on the heat release under EGR dilution and stoichiometric conditions was investigated on a single-cylinder gasoline engine. The performance of the HSASI spark plug was compared with a passive pre-chamber spark plug (PPCSP) and a conventional spark plug (SI) for different combustion phasings. Detailed combustion analyses were conducted and the signal from an ion current sensor located inside the pre-chamber as well as the engine out NO emissions were examined. Operation with the HSASI pre-chamber spark plug allows the ignition timing to be advanced when misfiring occurs with PPCSP and unstable engine operation prevails with SI. With the same combustion phasing, HSASI allows for retarding the ignition timing compared to PPCSP and SI by up to 28 °CA due to a faster flame development. HSASI operation shows less NO emissions than SI and similar to PPCSP for same combustion phasing. However, HSASI has higher efficiency losses due to incomplete combustion and higher wall heat losses compared to SI.</div></div>