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Letteratura scientifica selezionata sul tema "HBCD"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 10 marzo 2023

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Articoli di riviste sul tema "HBCD"

Isobe, Tomohiko, Hiroko Oda, Nozomi Takayanagi, Tatsuya Kunisue, Hiroaki Komori, Norimasa Arita, Norifumi Ueda et al. "Hexabromocyclododecanes in human adipose tissue from Japan". Environmental Chemistry 6, n. 4 (2009): 328. http://dx.doi.org/10.1071/en09024.

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Abstract (sommario):

Environmental context. Contamination by hexabromocyclododecanes (HBCDs), a group of brominated flame retardants, is of great concern due to their bioaccumulative nature and toxic implications. HBCD consumption in Japan is the highest among Asian countries and is still growing. In this regard, human exposure to HBCDs is of great concern in Japan. We present here the results of our investigation on Japanese human adipose tissue using LC-MS/MS. HBCDs were detected in all the samples analysed, and were generally higher in men than in women. Abstract. Residue levels of hexabromocyclododecanes (HBCDs) were measured using LC-MS/MS in the Japanese human adipose tissue samples collected during 2003–2004 from Ehime prefecture (n = 26) and Kanto region (n = 9) of Japan. Concentrations of HBCDs (0.85–39 ng g–1 lipid) in the adipose tissue samples were 1–2 orders of magnitude lower than those of organochlorines (OCs). Regional differences between HBCD levels in Ehime prefecture and Kanto region were not significant. No age-dependent accumulation of HBCDs was observed. HBCD levels in men were significantly higher than those in women. Significant positive correlation between polybrominated diphenyl ethers (PBDEs) and HBCDs implies similar routes of exposure to these contaminants for Japanese citizens. α-HBCD was predominant among the three isomers, which is consistent with the other reports on bioaccumulation of α-HBCD in higher trophic animals.

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Wang, Xueli, Xiaoyu Yuan e Shengke Yang. "Sorption Behavior of Hexabromocyclododecanes (HBCDs) on Weihe River Sediment". International Journal of Environmental Research and Public Health 17, n. 1 (30 dicembre 2019): 247. http://dx.doi.org/10.3390/ijerph17010247.

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Abstract (sommario):

The sorption of hexabromocyclododecanes (HBCDs) on sediment affects the fate and transport of HBCDs in rivers. The sorption of HBCDs on sediment from the Weihe River was investigated by performing batch equilibration experiments, and the effects of changing the pH ionic, strength, and humic acid concentration (HA) on sorption were evaluated. The obtained results indicated that fast rather than slow sorption was the dominant process. Nonlinear sorption isotherms were acquired, and the Freundlich (R2 0.94–0.98) and Langmuir (R2 0.95–0.99) models both described the sorption of HBCDs well. The adsorption capacity for α-HBCD, β-HBCD, and γ-HBCD were calculated using the Langmuir model, and were 443.56, 614.29 and 1146.37 mg/kg, respectively. Thermodynamic analysis shows that HBCDs sorption on sediment is a spontaneous exothermic process. HBCDs sorption was affected by the HA concentration and ionic strength. The amounts of HBCDs sorbed to the sediment decreased as the ionic strength increased, and first increased and then decreased as the HA concentration increased. Changes in pH did not clearly affect the sorption of HBCDs. Synchrotron radiation Fourier-transform infrared spectra (SR-FTIR) was used to characterize the adsorption mechanism, and the obtained result indicated that hydrophobic interactions dominated the mechanism involved in HBCDs sorption on sediment.

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Zhang, Xian, Dandan Zhang, Zhuanxi Luo, Lifeng Lin e Changzhou Yan. "Diastereoisomer- and enantiomer-specific profiles of hexabromocyclododecane in the sediment of Dongjiang River, South China". Environmental Chemistry 8, n. 6 (2011): 561. http://dx.doi.org/10.1071/en10136.

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Abstract (sommario):

Environmental contextHexabromocyclododecanes are widely used as additive brominated flame retardants in thermal insulation building materials, upholstery textiles and electronic products. Dongjiang River is located at the Pearl River Delta, one of the most highly industrialised regions in China, which was seriously polluted by hexabromocyclododecanes. Higher levels of hexabromocyclododecanes in Dongjiang River will pose a serious threat to ecological health in this region. AbstractThe objective of this study was to investigate the levels, diastereoisomer profiles and enantiomeric fractions of hexabromocyclododecanes (HBCDs) in the sediment of the Dongjiang River, China. The results showed that the total HBCD concentrations in the sediment ranged from below 2.5 to 424.16 ng g–1, which is similar to levels downstream of point source discharges in Europe and significantly higher than HBCD levels in sediments from rivers in the USA. The diastereoisomeric pattern showed the predominance of the γ-isomer, with low contributions of the α- and β-isomers. This diastereoisomer profile of the HBCDs was similar to that of commercial formulations. No uniform enantioselective enrichment was observed for α- and β-HBCD in sediments, which suggested that different stereoselective biotransformations occurred for these two isomers at different sites. However, (–)-γ-HBCD was apparently enriched in the sediment, which suggested that HBCDs in these studied sites were selectively biodegraded by microorganisms in the sediment.

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Wang, Xueli, Xiaoyu Yuan, Shengke Yang e Yaqian Zhao. "Concentrations, Distributions, and Risk Assessment of HBCD in Sediment in the Weihe River Basin in Northwest China". International Journal of Environmental Research and Public Health 15, n. 11 (23 ottobre 2018): 2340. http://dx.doi.org/10.3390/ijerph15112340.

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Abstract (sommario):

As one of the most widely used brominated flame retardants, hexabromocyclododecane (HBCD) is found widely in the environmental media. In this study, the content and spatial distribution of HBCD and risk posed by HBCD in surface sediment in the Weihe River Basin in Northwest China were investigated. The HBCD concentration ranged nd–4.04 ng/g dw with the mean was 0.45 ng/g dw. The major source of HBCD in surface sediment was local point discharge. The distribution profiles of α-, β-, γ-HBCD were 24.7–87.9%, 0–42.0%, and 0–67.1%, respectively. Specially, α-HBCD was the dominating isomer in most sample sites. This differed significantly from that in HBCD technical product, which might be attributed to the different degradation rates and inter-transformation of the three HBCD isomers. Risk quotient method was used to assess the potential risk posed by HBCD in sediment. HBCD do not pose strong risks to aquatic algae organisms in the Weihe River Basin.

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Reindl, Andrzej, Lucyna Falkowska e Agnieszka Grajewska. "Hexabromocyclododecane contamination of herring gulls in the coastal area of the southern Baltic Sea". Oceanological and Hydrobiological Studies 49, n. 2 (25 giugno 2020): 147–56. http://dx.doi.org/10.1515/ohs-2020-0014.

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AbstractMuscles and livers of herring gulls (Larus argentatus) found in the coastal area of the southern Baltic Sea were tested for the presence of hexabromocyclododecane (HBCD) isomers. They were detected in the muscles (ΣHBCD = 42.82 ± 30.65 ng g−1 l.w.) and livers (ΣHBCD = 65.51±27.96 ng g−1 l.w.) of all examined gulls. The α-HBCD isomer dominates in all types of samples. Our study has shown that bodies of gulls are less contaminated with HBCD than bodies of aquatic birds from other regions of the world. There was no clear correlation between HBCD concentrations and sex and age of birds. Nevertheless, it was indicated that the highest concentrations of HBCD and the α-HBCD isomer were found in the livers of immature females (mean = 89.31 ± 21.63 ng g−1 l.w. and mean = 76.72±24.54 ng g−1 l.w., respectively). The highest liver sequestration rates of the α-HBCD isomer were found in both adult and immature males (mean = 7.7 ± 13.7 and mean = 6.2 ± 11.9, respectively).

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Monfared, Yousef Khazaei, Mohammad Mahmoudian, Gjylije Hoti, Daniel Mihai Bisericaru, Fabrizio Caldera, Roberta Cavalli, Parvin Zakeri-Milani, Adrián Matencio e Francesco Trotta. "Hyper-Branched Cyclodextrin-Based Polymers as Anticoagulant Agents: In Vitro and In Vivo Studies". Bioengineering 9, n. 12 (4 dicembre 2022): 765. http://dx.doi.org/10.3390/bioengineering9120765.

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This study tested the anticoagulant effect of cyclodextrin (CD) hyper-branched-based polymers (HBCD-Pols). These polymers were synthesized and tested for their coagulant characteristics in vitro and in vivo. Due to their polymeric structure and anionic nature, the polymers can chelate Ca2+, reducing the free quantity in blood. HBCD-Pol increased the blood clotting time, PT, and aPTT 3.5 times over the control, showing a better effect than even ethylenediaminetetraacetic acid (EDTA), as occured with recalcification time as well. A titration of HBCD-Pol and EDTA showed exciting differences in the ability to complex Ca2+ between both materials. Before executing in vivo studies, a hemocompatibility study was carried out with less than 5% red blood cell hemolysis. The fibrinogen consumption and bleeding time were analyzed in vivo. The fibrinogen was considerably decreased in the presence of HBCD-Pol in a higher grade than EDTA, while the bleeding time was longer with HBCD-Pols. The results demonstrate that the anticoagulant effect of this HBCD-Pol opens novel therapy possibilities due to the possible transport of drugs in this carrier. This would give combinatorial effects and a potential novel anticoagulant therapy with HBCD-Pol per se.

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Zeng, WenXian, e Takato Terada. "Freezability of boar spermatozoa is improved by exposure to 2-hydroxypropyl-beta-cyclodextrin". Reproduction, Fertility and Development 12, n. 4 (2000): 223. http://dx.doi.org/10.1071/rd00058.

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Abstract (sommario):

The influence of 2-hydroxypropyl-beta-cyclodextrin (HBCD) exposure on post-thaw spermatozoa prior to freezing using acrosome integrity and the parameters of motility was studied. Acrosomal status was monitored by means of FITC-labelled peanut agglutinin, and the motility parameters were assessed using a computer-assisted sperm motility analysis (CASA) system. The spermatozoa were exposed to HBCD over a period of 3 h, during which the cells were slowly cooled from 25 to 5˚C, and then frozen into pellets. The percentage of frozen–thawed spermatozoa with intact acrosomes in 40 mM HBCD group was approximately three-fold higher than that of the control. The motility and progressive motility values of the frozen–thawed spermatozoa were found to increase significantly with increased HBCD concentrations. On the other hand, further addition of cholesterol-3-sulfate to the BF5 extender containing 20 mM HBCD resulted in a drastic decrease in the percentage of spermatozoa with intact acrosomes, and decreased motility and progressive motility, suggesting that cholesterol-sulfate probably counter-acted the protective action of HBCD. In conclusion, the results of the present study indicate that HBCD protected boar spermatozoa against freeze–thaw damage, possibly by means of stimulating the efflux of membrane cholesterol.

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Okšová, Linda, e Peter Tölgyessy. "Determination of Hexabromocyclododecanes in Fish Using Modified QuEChERS Method with Efficient Extract Clean-Up Prior to Liquid Chromatography–Tandem Mass Spectrometry". Separations 7, n. 3 (6 agosto 2020): 44. http://dx.doi.org/10.3390/separations7030044.

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Abstract (sommario):

A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation method coupled with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was proposed for the determination of α-, β-, and γ-hexabromocyclododecane (HBCD) diastereomers in whole-fish homogenate samples. The main modification of the QuEChERS method concerned a clean-up step in which the combination of pH-tuned dispersive liquid–liquid microextraction (DLLME) with 18.4 M H2SO4 digestion allowed to successfully eliminate the matrix substances from the final extract. For the target HBCDs, good response linearity was obtained with coefficients of determination (R2) >0.998 for the concentration range corresponding to 0.1–50 ng of analyte per g of sample. Limits of quantifications (LOQs) were 0.15–0.25 ng g−1 ww (wet weight), and the recoveries from samples spiked at levels of 0.5 and 5 ng g−1 ranged from 89% to 102% with relative standard deviations <7.5%. The accuracy of the method was verified by analysis of the NIST standard reference material SRM 1947, and a good agreement (90%) was obtained with the certified value for the α-HBCD present in the sample. Finally, the method was applied to the analysis of 293 fish samples collected in water bodies from all over Slovakia, in which the highest concentrations were determined for α-HBCD with the maximum value of 31 ng g−1 ww.

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Chiriac, Florentina Laura, Liliana Cruceru, Marcela Niculescu, Luoana Florentina Pascu, Carol Blaziu Lehr e Toma Galaon. "Simultaneous Determination of alfa-, beta- and gama-hexabromocyclododecane Diastereoisomers in Sewage Sludge using Liquid Chromatography Tandem Mass Spectrometry". Revista de Chimie 68, n. 8 (15 settembre 2017): 1685–89. http://dx.doi.org/10.37358/rc.17.8.5744.

Testo completo

Abstract (sommario):

Hexabromocyclododecane (HBCD) is a large-scale usage brominated flame retardant consisting of a mixture of diastereoisomers which has been reported as an ubiquitous environmental contaminant. HBCD has attracted much attention due to its toxicity and increasing levels in waste water sewage sludge. Since November 2014, HBCD was added to the Persistent Organic Pollutants list of the Stockholm Convention which generated a higher concern regarding its presence in the environment. A rapid (8 min) and accurate liquid chromatography electrospray ionization tandem mass spectrometry method (LC-ESI-MS/MS) was developed to separate and detect a-, b- and g-HBCD isomers from sewage sludge. Optimization of LC-MS parameters (column temperature, mobile phase composition and flow, collision energy, fragmentor voltage, capillary voltage and drying gas temperature) allowed complete separation of the three isomers and also very good detection sensitivity with instrumental quantitation limits (IQLs) between 0.3 and 0.6 ng/mL. The three isomers were separated on a C18 reversed-phase column, kept at 18�C, using a H2O/ACN/MeOH mobile phase mixture and detected by negative electrospray ionization using MRM mode with two transitions, one for quantitation and one for confirmation. MS detector response was linear in the range 1.0 � 100.0 ng/mL with correlation coefficients (R2) higher than 0.99 for all three isomers. A simple ultrasonic assisted liquid-solid extraction procedure using a solvent mixture was employed to extract HBCD isomers from WWTP sewage sludge. Overall method intra-day and inter-day precision (RSD%) were situated between 7.6 � 9.2% and 10.3 � 14.5%, respectively. LOQs for a-, b- and g-HBCD were 1.4, 0.7 and 1.0 ng/g, comparable and even lower to those reported by similar studies concerning HBCD presence in WWTP sewage sludge. HBCD presence was tested from several WWTP sludge samples. All three isomers were found with 100% detection frequency ranging from 3 to 76 ng/g.

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Zhang, Ying, Sijia Li, Yafeng Zhang, Yezi Chen, Xutao Wang e Yuxin Sun. "Bioaccumulation and Biomagnification of Hexabromocyclododecane in Marine Biota from China: A Review". Toxics 10, n. 10 (19 ottobre 2022): 620. http://dx.doi.org/10.3390/toxics10100620.

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Abstract (sommario):

Hexabromocyclododecane (HBCD) was listed in Annex A of the Stockholm Convention on Persistent Organic Pollutants for its persistence, bioaccumulation and toxicity, and pose significant adverse effects on natural environments and human health. HBCDs are ubiquitously found in marine environments worldwide and can be biomagnified in marine organisms with a high trophic level. In the present study, we reviewed the available data on contamination of HBCDs in the marine biota from China, including mollusks, crustaceans, fish and mammals. Bioaccumulation and biomagnification of HBCDs in the marine food web were summarized as well. This study also prospected the future research of HBCDs, including the transport and fluxes of HBCDs to and within the marine environment, the biomagnification of HBCDs in different ecosystems, and the metabolism of HBCDs in different marine species.

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Più fonti

Tesi sul tema "HBCD"

Sundvall, Börje, e Linda Johansson. "Metodutveckling för analys av PBDE och HBCD i sediment". Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-870.

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Abstract (sommario):

Brominated flame retardants (BFRs) has for many years been used in products to reduce their

flammability, mainly in electronic products, textiles and construction materials.

In 2003, Sweden imported 300 tons of brominated flame retardants.

Leakage of these compounds has polluted natural environments. Fishes has shown increased

contents of these substances, especially fat fish, since brominated flame retardants tends to

accumulate in fatty tissues.

They are also regarded as persistent and that gives them the ability to travel long distances.

What also is really scary is that increased levels of brominated flame retardants have been

detected in human breast milk.

The knowledge of the brominated flame retardants is limited and not so much research has been

done in this field. There are many reasons though, to keep the research going. Partly their

structural resemblance to well-known toxics as PCB, but also their ability to accumulate in

biological systems and enrich in food chains.

In which way they affect humans we really don’t know yet. Experiments on mice have been done

and behavioural disturbances were observed as well as a decrease in learning capacity.

The BRFs chosen for this study are hexabromocyclododecan (HBCD) and a polybrominated

diphenyl ether (PBDE) called pentabromodiphenylether (BDE 99).

About 25 % of the flame retardants produced in the world every year, consists of the brominated

ones. If we look at the PBDEs it’s mainly tetrabromodiphenylether (BDE 47),

pentabromodiphenylether (BDE 99), octabromodiphenylether (BDE 205) and

decabromodiphenylether (BDE 209) that are common flame retardants.

As from July 1st 2006, PBDE was forbidden in electric and electronic products (15).

January 1st 2007, a Swedish prohibition concerning the use of BDE-209 was established. BDE-

209 is not allowed on the Swedish market if the content of substance exceed 0,1 percent of weight

(23).

BDE-99 is classified as environmentally dangerous and a healthrisk. It´s not only toxic for

waterliving organisms but also for humans if exposed during a long time (19).

We shall develop a well functioning, reproducible and economic method to analyse HBCD and

PBDE in sediment. It includes extraction, cleanup and sample analyses with a ECD (electron

capture detector) equipped capillary gas chromatograph.

Several analyses of adequate diluted standards has been analysed in a GC-ECD to find suitable

temperature gradients. Then we produced spiked sediment samples with known amounts of

standards. To homogenize the spiked samples we used a mixer. As a first step in the extraction we

used acetone as a solvent. Then we used cyclohexane and NaCl (2%) to separate the nonpolar and

polar substances from each other. Cleanup with concentrated sulphuric acid was done and for

some samples we also used Florisil. To concentrate the extract it was evaporated with N2(g).The

extract was then analysed in a GC-ECD and then the results was compared with the standards.

The result of this project showed that our method of extraction is useful. We managed to extract

50 % HBCD, 30 % BDE-99 and 60 % BDE-99 (dried sediment).

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Persson, Josefin. "Development and evaluation of methods for analysis of TBECH and HBCD using HRGC/HRMS and HPLC/MS/MS". Thesis, Örebro University, School of Science and Technology, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-7695.

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Abstract (sommario):

The two additive brominated flame retardants, tetrabromoethylcyclohexane (TBECH) and hexabromocyclododecane (HBCD) are used to prevent fire to start and spread. They are simply mixed with material and are most likely to leach out in the environment, because of non-covalently binding to the material. TBECH can exist as four pairs of enantiomers, α-, β-, γ- and δ-TBECH. The technical HBCD can exist as three pairs of enantiomers, α-, β- and γ-HBCD and two meso forms δ- and ε-HBCD. None of these compounds are produced in Sweden, but they are imported to industries. TBECH has been found in Beluga blubber and can accumulate in zebrafish. HBCD has been found in water environments and can be toxic to and bioaccumulate in water-living animals.

In this study, a method was developed for separation and detection of α-, β-, γ- and δ-TBECH on HRGC/HRMS. All TBECH-isomers could be separated with the developed method. How much of the TBECH isomers that were recovered after applying existing extraction and clean-up procedures, normally applied for clean-up and extraction of PCBs and PCDD/Fs, was evaluated. Low recovered amounts (6.8-35.5 %) of TBECH-isomers added in known amounts to three different whale samples indicate severe evaporation losses and possibly photolytic degradation. None of the four enantiomers were detected in the three whale samples. For HBCD analysis, both the chromatography and MS/MS parameters were optimised for δ- and ε- HBCD yielding good chromatography and sensitivity. However, due to technical difficulties during the time-period of this project, no whale samples could be analysed for HBCD on UPLC/MS/MS.

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Domínguez-Romero, Elena. "Modélisation du devenir de l’hexabromocyclododécane (HBCD) chez la poule pondeuse : influence des caractéristiques physiologiques". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0167/document.

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Abstract (sommario):

L’hexabromocyclododécane (HBCD) a été utilisé comme additif dans des polystyrènes (PS). En 2013, l’HBCD a été inclus à la Convention de Stockholm comme Polluant Organique Persistant. Les denrées alimentaires d’origine animale (DAOA) constituent la source principale d’exposition de la population générale à ce polluant. Le niveau moyen d’exposition du consommateur ne représente pas un risque majeur pour la sécurité sanitaire des aliments (EFSA, 2011). Malgré des concentrations moyennes généralement proches d’un ng g-1 lipides dans les DAOA, des concentrations maximales supérieures à 2000 ng g-1 lipides dans certains échantillons d’œuf ont été rapportées. Plusieurs sources potentielles d’exposition orale des volailles existent. Les poules pondeuses pourraient être exposées majoritairement à l’isomère α-HBCD. Au vu de l’absence d’informations dans la littérature sur le devenir de l’α-HBCD chez la poule pondeuse, une expérimentation in vivo a été réalisée et a permis d’estimer la plupart des paramètres cinétiques du devenir de l’α-HBCD ingéré chez la poule pondeuse. Un modèle pharmacocinétique basé sur la physiologie (PBPK) de transfert de l’α-HBCD chez la poule pondeuse a été développé, calibré par des données de la littérature, soumis à analyse de sensibilité et plusieurs paramètres ont été ajustés sur des résultats in vivo. Une validation du modèle a été testée. Ce modèle a permis de déterminer l’influence des caractéristiques physiologiques de la poule pondeuse sur le devenir de l’α-HBCD en cas d’exposition à la molécule. Parmi les caractéristiques d’intérêt, le poids vif (PV) est celle qui influence le plus la concentration d’α-HBCD dans les tissus et les œufs. Un PV bas et des performances de ponte réduites prédisposent à une concentration plus élevée dans ces matrices. La mue produit une augmentation de la charge corporelle de la molécule. Ce modèle peut être extrapolé à d’autres animaux et molécules lipophiles après modification de certains paramètres
Hexabromocyclododecane (HBCD) has been used as an additive in polystyrene (PS). In 2013, HBCD was included in the Stockholm Convention as a Persistent Organic Pollutant. The foodstuffs of animal origin are the main source of exposure of the general population to this pollutant. The mean exposure level of the consumers to HBCD doesn’t represent a major risk to the food safety (EFSA, 2011). In spite of mean concentrations generally close to 1 ng g-1 lipids in the foodstuffs of animal origin, maximal concentrations higher than 2000 ng g-1 lipids have been reported in some egg samples. There are several potential sources of oral exposure of the hens to this pollutant. The hens could be exposed mainly to the α-HBCD isomer. Since the bibliographic synthesis highlights the absence of information about the α-HBCD kinetics in the laying hen, an in vivo experience has been realized and has allowed the estimation of the majority of the α-HBCD kinetic parameters in the laying hen. A physiologically based pharmacokinetic (PBPK) model has been developed, calibrated by literature data, submit to a sensitivity analysis and some parameters have been adjusted on the basis of experimental data. A validation of the model has been attempted. This model has allowed to determine the influence of the main physiological characteristics of the laying hen exposed to the molecule on the α-HBCD accumulation in tissues and transfer to eggs. Among the physiological characteristics of concern, the body weight (BW) is the main feature influencing the α-HBCD kinetics. If the hen is exposed to the α-HBCD, a low BW and low laying performances predispose the hen to have higher concentrations of the molecule in all the matrices. The molting stage raises the body charge of the molecule. This model can be extrapolated to other animals and lipophilic molecules after modification of some parameters

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Esslinger, Susanne. "Hexabromcyclododecan". Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16845.

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Abstract (sommario):

Das Ziel dieser Arbeit war die Untersuchung des enantiomerenspezifischen Umweltverhaltens des Flammschutzmittels Hexabromcyclododecan (HBCD). Zu Beginn erfolgte daher die Optimierung und Validierung eines enantiomerenspezifischen Analysenverfahrens für die Bestimmung von HBCD in Biota. Die errechneten mittleren Wiederfindungen lagen im Bereich von 100-102 % und die Nachweisgrenzen zwischen 0,131 und 0,255 pg g-1. Untersuchungen zur ubiquitären Verteilung von HBCD erfolgten an Eiern der Silbermöwe deutscher Nord- und Ostseeinseln (Probenahme 1988-2008). In allen Fällen dominierte alpha-HBCD das Diastereomerenmuster, wobei eine bevorzugte Anreicherung von (-)-alpha-HBCD sowie ein zeitlicher Trend aller Enantiomeren-Gehalte festgestellt wurde. Zur Klärung der Frage einer Bioakkumulation sowie -isomerisierung der HBCD-Stereoisomere erfolgten Langzeit-Fütterungsversuche an Spiegelkarpfen. Die Untersuchungen ergaben eine signifikante Akkumulation des jeweils gefütterten HBCD-Enantiomers, jedoch konnte die Hypothese der Bioisomerisierung nicht bestätigt werden. Ein weiterer Schwerpunkt lag in Untersuchungen zur cytochromabhängigen enantiomerenspezifischen Biotransformation von HBCD im Rahmen des Metabolismus an Lebermikrosomen diverser Spezies. Hier konnte gezeigt werden, dass HBCD dem Phase I-Metabolismus unterliegt und hydroxyliert wird. Dabei weist jedes HBCD-Enantiomer ein spezifisches Metabolitenmuster auf, was eine Zuordnung der hydroxylierten Verbindungen zum entsprechenden HBCD-Enantiomer erlaubt. Anhand von Zeitreihen sowie der Berechnung von Halbwertszeiten konnte der Verdacht eines enantiomerenspezifischen Metabolismus in Richtung einer Anreicherung von (-)-alpha- und (+)-gamma-HBCD bestätigt werden. Inkubationsansätze mit reinen Cytochrom (CYP)-Isoformen sowie molekülmechanische Berechnungen legen die Vermutung nahe, dass dem CYP3A4 eine Schlüsselrolle bei der Metabolisierung von HBCD zukommt.
The main emphasis of this thesis was on the enantio-specific environmental behaviour of the polybrominated flame retardant hexabromocyclododecane (HBCD). Initially, an enantio-specific analytical method for the determination of HBCD in biota was optimised and validated. The calculated mean recoveries ranged from 100 to 102 % and the limits of detection are in the range of 0.131 to 0.255 pg g-1. First investigations of the ubiquitous environmental distribution of HBCD were performed using herring gull eggs from different islands in the North and Baltic Sea (sampling 1988 to 2008). In all cases alpha-HBCD was the predominant diastereomer. Significant deviations from the racemic mixture revealed a preferred enrichment of the first eluting (-)-alpha-HBCD. In addition, a temporal trend of HBCD levels was observed. To clarify the issue of accumulation as well as bioisomerisation of HBCD stereoisomers, a long-term feeding study with mirror carps was performed. The results showed an accumulation of each initially fed HBCD enantiomer, but hypothesis of a bioisomerisation could not be confirmed. Another important focus of this work was to study the cytochrome-dependent enantio-specific biotransformation of HBCD enantiomers in various species of liver microsomes. It was shown that HBCD is subject to phase I metabolism. In the course of this process, HBCD is metabolised to hydroxylated products, whereas each HBCD enantiomer results in a specific metabolite pattern allowing the allocation of the corresponding hydroxylated compounds. Investigation of time series as well as the calculation of half-lives, the hypothesis of an enantio-specific metabolism towards an enrichment of (-)-alpha- and (+)-gamma-HBCD could be confirmed. Incubation mixtures with pure cytochrome (CYP) isoforms, as well as molecular mechanic calculations suggest that CYP3A4 plays a key role in the biotransformation processes of HBCD.

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Reffatto, Valentina. "Evaluation of the toxicity of the brominated flame retardants, PBDE-47 and HBCD, in neuronal cell lines". Thesis, King's College London (University of London), 2012. https://kclpure.kcl.ac.uk/portal/en/theses/evaluation-of-the-toxicity-of-the-brominated-flame-retardants-pbde47-and-hbcd-in-neuronal-cell-lines(b9cc43ec-9519-40f4-87b3-607e24eeb2dd).html.

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Polybrominated diphenyl ether (PBDE-47) and hexabromocyclododecane (HBCD) are brominated flame retardants (BFRs) commonly used in a wide range of consumer products. They bioaccumulate and persist in the environment, and have been detected in humans and wildlife. Their ability to pass the blood-brain barrier (BBB) and to accumulate in the brain has raised concern about the potential of BFRs to cause neurotoxicity. Functional genomics was used to investigate the modes of action of PBDE-47 and HBCD in two neuronal cell models namely mouse neuroblastoma (N2A) and neuroblastoma x spinal cord (NSC-19). It was established that PBDE-47 and HBCD reduce cell viability, increase lactate dehydrogenase (LDH) leakage and cause apoptosis as indicated by increased caspase-3 activity at low micromolar concentrations (1 - 4μM). A pre-incubation with the omega-3 fatty acid, docosahexaenoic acid (DHA), mitigated the toxic effect of HBCD in the N2A cell line, with a significant decrease in the LDH leakage. Transcriptome profiling revealed that exposure to PBDE-47 and HBCD affects expression of genes with overlapping functionalities. Both toxicants regulated genes related to calcium homeostasis, endoplasmic reticulum stress and lipid metabolism. Genes involved in thyroid hormone signalling, neurodegenerative diseases and nervous system development were also preferentially regulated. The fatty acid DHA altered the expression of genes that were also regulated by PBDE-47 or HBCD, and HBCD modulated DHA-induced gene expression. It was also established that HBCD exposure affect cellular zinc homeostasis, increasing the level of intracellular weakly bound Zn2+. This effect was ameliorated by the antioxidant NAC, suggesting that the [Zn2+] increase could have been caused by oxidative stress with release of Zn2+ from zinc-binding proteins. This result indicates for the first time that zinc signalling is a potential target of POP toxicity. In conclusion, we established that PBDE-47 and HBCD have toxicity effects on cells of neuronal origin starting at a concentration of 1μM and that exposure to either of these BFRs causes regulation of genes related to many cellular functions, several of which have been observed as BFR phenotypes in animal studies. It was also shown that zinc is a POP toxicity target and that cellular effects of BFRs are modulated by DHA.

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Kobiliris, Demetrios. "Influence of embryonic exposure to hexabromocyclododecane (HBCD) on the corticosterone response and "fight or flight" behaviours of captive American kestrels". Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95190.

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Hexabromocyclododecane (HBCD) is a brominated flame retardant commonly used in industrial and household products to reduce the spread of fire and the risk of death. Similar to polybrominated diphenyl ethers (PBDEs), HBCD is a ubiquitous and persistent environmental contaminant, highly lipophilic and bioaccumulative, and has been detected throughout various ecosystems and phyla, thus posing potential cause for concern for top consumer species, including birds of prey. Captive adult American kestrels (Falco sparverius) were exposed by diet to HBCD at an estimated daily concentration of 0.8 μg HBCD / μL safflower oil per cockerel (or 800 ng/ g ww / day / pair); their offspring, used in this study, were exposed in ovo only to environmentally relevant HBCD concentrations of 164.13 ± 18.26 ng/g ww or to background concentrations in the control eggs (0.4 ± 0.04 ng/g ww). The in ovo exposed HBCD group of male nestling kestrels showed a reduced corticosterone response. Moreover, in ovo HBCD concentrations were correlated with reduced flying activities of juvenile males during hunting behaviour trials and delayed response times of juvenile female kestrels during predator avoidance behaviour trials, suggesting an ongoing effect of HBCD on corticosterone levels. These findings show that embryonic exposure to environmentally relevant concentrations of technical mixture HBCD influences the corticosterone response, hunting success and avoidance of potential predators in captive American kestrels.
L'Hexabromocyclododécane (HBCD) est un ignifuge bromé couramment utilisé dans les produits industriels et ménagers pour réduire les risques d'incendies et de mortalité. À l'instar des éthers diphényliques polybromés (EDPB), le HBCD est un polluant omniprésent et persistant de l'environnement, fortement lipophile et bioaccumulable, décelé dans divers écosystèmes et phylums et donc potentiellement préoccupant pour les espèces du haut de la chaîne alimentaire, dont les oiseaux de proie. L'étude consiste à exposer par leur alimentation des crécerelles d'Amérique (Falco sparverius) adultes en captivité à une concentration quotidienne estimée de 0,8 mg HBCD / μL d'huile de carthame par coquelet (c.-à-d. 800 ng / g pf/ jour / paire); leur progéniture, utilisée dans cette étude, ont été exposés in ovo à des concentration écologiquement pertinentes de HBCD 164,13 ± 18,26 ng / g pf ou des concentrations de fond (0,4 ± 0,04 ng / g pf) dans le cas des ufs de contrôle . Chez les oisillons mâles du groupe exposé au HBCD in ovo, il y a réduction de la sécrétion de corticostérone. En outre, les concentrations de HBCD in ovo sont corrélées à une réduction des activités de vol chez les mâles juvéniles durant des essais de comportement de chasse et des temps de réaction accrus chez les femelles juvéniles durant des essais de comportement d'évitement de prédateurs, ce qui suggère un effet continu du HBCD sur les niveaux de corticostérone. Ces constatations démontrent que l'exposition embryonnaire à des concentrations écologiquement pertinentes de HBCD dans un mélange technique a une incidence sur le taux de sécrétion de corticostérone, le taux de réussite des activités de chasse et l'évitement de prédateurs potentiels chez la crécerelle d'Amérique.

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Sahlström, Leena. "Linking exposure pathways to internal concentrations of brominated flame retardants in Swedish mothers and their toddlers". Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-107592.

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Brominated flame retardants (BFRs) have been used in a variety of consumer products to enhance their fire safety. This has resulted in exposure of the environment, wildlife and humans causing risks of endocrine disruption. The use restrictions of many BFRs have resulted in the introduction of other brominated chemicals (emerging BFRs) on the market. Humans are exposed to BFRs primarily via diet and dust ingestion, but the importance of the different exposure pathways has scarcely been studied. Children in particular have not been studied well due to lack of biomonitoring data. In this thesis, a mother-toddler cohort (n=24) from Uppsala was studied for their exposure to tri-decabrominated diphenyl ethers (tri-decaBDEs), isomer-specific hexabromocyclododecanes (HBCDs) and emerging BFRs (EBFRs). A clean-up and fractionation method was developed for determination of the above-mentioned BFRs in the same sample without dividing the sample. Measures of external exposure from dietary intake and dust ingestion were estimated. These were compared to internal concentrations (serum, feces) to determine which exposure pathways were most important for explaining the different BFR concentrations and patterns found in mothers and toddlers. Taking all the results into account, the toddlers’ higher serum levels of tetra-pentaBDEs seem to be the result of previous breastfeeding and those of octa-decaBDEs from exposure to house dust. For mothers, diet was estimated to be the main exposure route of tri-hexaBDEs and HBCDs. Dust ingestion was estimated to be the main route for BDE-209 exposure in mothers. Significant correlations were found between the tetra-decaBDE concentrations in matched serum and feces samples indicating that feces could be used as a non-invasive sample matrix for biomonitoring of PBDEs in toddlers. EBFRs were detected in the feces of toddlers and in a few serum samples from both mothers and toddlers indicating that exposure to these replacement chemicals occurs.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.

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Stefanovic, Vanja. "Effect of PFOS and HBCD on the lipid profiles of developing rainbow trout (Onchorhynchus mykiss) analyzed with UHPLC/Q-TOF-MS". Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-71044.

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Perfluorooctane sulfonate (PFOS) is widely used in industrial products and is potentially dangerous to the aquatic environment due to not being broken down whether by chemical or biological means, having a half-life of more than 41 years and disrupting hormones. Hexabromocyclododecane (HBCD) is the third most used brominated flame retardant and is of environmental concern as it bioaccumulates and magnifies in the food chain and is highly toxic to aquatic organisms. The purpose of this study was to examine the effect of PFOS and HBCD on the embryos of rainbow trout (Onchorhynchus mykiss) by analyzing lipid profiles with UHPLC/Q-TOF-MS. The fish embryos were treated with various concentrations of PFOS and HBCD (0.058-58 μg/l and 0.014-14 μg/l respectively) with DMSO as carrier solvent and then extracted after homogenization with 0.9% NaCl-solution followed by addition of ISTD mixture, methanol, methyl tert-butyl ether (MTBE) and MQ-water. The raw data was processed with MZmine-2.32. 153 lipids were identified with the main lipids consisting of glycerophospholipids and triacylglycerols. A two-tailed t-test was used to study the impact of the chemical exposure on the embryos, where p-values below 0.05 were lipids considered as significant change. The HBCD exposure caused significant change in various triacylglycerols, whereas PFOS exposure caused significant change in triacylglycerols as well as in glycerophospholipids such as PC(O-38:5) and LPC(20:4). The results were in alignment with previous studies.

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Björklund, Justina. "Brominated flame retardants and perfluoroalkyl acids in Swedish indoor microenvironments : Implications for human exposure". Doctoral thesis, Stockholms universitet, Institutionen för tillämpad miljövetenskap (ITM), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-63701.

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Humans are exposed to persistent organic pollutants (POPs) such as brominated flame retardants (BFRs, specifically polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD)) and perfluoroalkyl acids (PFAAs, specifically perfluoroalkane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)). They are used in consumer products found in cars, offices, homes and day care centers. Diet was earlier thought to be a major human exposure route for legacy POPs, but does not account for body burdens found for many new POPs and indoor exposure from air and dust has been hypothesized as also important. In this thesis, BFRs in air and dust, and PFAAs in dust from different indoor microenvironments in Sweden were analysed, and the results used to estimate human exposure. BFRs and PFAAs were detected in dust from all microenvironments and PBDEs in all air samples. BFR and PFAA exposure occurs mostly in peoples’ homes with toddlers having higher intakes from dust ingestion than adults. Inhalation and dust ingestion play minor roles compared to diet for humans with median exposures, but in worst case scenarios, dust ingestion may be significant for a small part of the Swedish population. Sampling using home vacuum cleaner bag dust and researcher-collected above floor dust was compared. Correlations were seen for ∑OctaBDE and ∑DecaBDE but not for ∑PentaBDE and HBCD. Higher PBDE concentrations were found in above floor dust but higher HBCD concentrations were found in vacuum cleaner bag dust. BDE-47 concentrations were correlated between vacuum cleaner bag dust and breast milk, indicating exposure through dust ingestion. Similar concentrations of PBDEs were measured in indoor and outgoing air from day care centers, apartment and office buildings. Indoor air explained 54-92% of ∑PentaBDE and 24-86% of BDE-209 total emissions to outdoor air in Sweden, supporting the hypothesis that the indoor environment is polluting ambient air via ventilation systems.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted. Paper 3: Accepted. Paper 4: Manuscript.

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Söderström, Gunilla. "On the combustion and photolytic degradation products of some brominated flame retardants". Doctoral thesis, Umeå University, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-107.

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Many modern products, especially electronic goods, are protected by brominated flame retardants (BFR). Some of the most common flame retardants are polybrominated diphenylethers (PBDE), tetrabromobisphenol-A (TBBP-A) and hexabromocyclododecane (HBCD). These compounds have been found in environmental samples and shown to have physiological effects on experimental animals. This thesis considers end-of-life aspects of brominated flame retardants. When spread in the environment, these compounds may be degraded into other forms. For example, if sludge contaminated with PBDE is used as an agricultural fertilizer, the PBDE could be degraded by sunlight to species of PBDE with lower degree of bromination and, to some extent, also form polybrominated dibenzofurans (PBDF). In addition, PBDF and polybrominated dibenzo-p-dioxins (PBDD) are formed during combustion of brominated flame retardants. When waste products with brominated flame retardants are co-combusted with household waste or other chlorinated fuel, polybrominated- chlorinated dibenzo-p-dioxins (PBCDD) and polybrominated- chlorinated dibenzofurans (PBCDF)will be formed. The bromin/chlorine composition of dioxins and furans is dependent on the bromine/chlorine ratio in the fuel, but the types of brominated flame retardants that are being combusted is less important. In the studies reported here, bromine levels higher than "normal" for household waste has been used. The results show that there is a pronounced increase in total dioxin levels in fluegas when when bromine is present, implying that waste containing brominated flame retardants should only be incinerated at combustion plants with effecient air pollution control devices.

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Libri sul tema "HBCD"

White, Rachel. MONOLISA anti-HBc PLUS. London: MHRA, 2003.

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Guelachvili, G., a cura di. Linear Triatomic Molecules - BClH+ (HBCl+) - COSe (OCSe). Berlin/Heidelberg: Springer-Verlag, 1995. http://dx.doi.org/10.1007/b46104.

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White, Rachel. Ortho HBc ELISA test system. London: MHRA, 2003.

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The politics of success: An HBCU leadership paradigm. Atlanta, Ga: Atlanta University Center, Robert W. Woodruff LIbrary, 2012.

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D, Sanders Yvonne, Freeman Yvonne B, George M. C, Alabama A & M University. e United States. National Aeronautics and Space Administration., a cura di. NASA-HBCU space science and engineering research forum proceedings. Huntsville, Ala: Alabama A & M University, 1989.

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Harris, Gloria D. The Scholarship And Hbcu Guide For African American Students. S.l: Aardvark Publishing Company, 2005.

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A, Page Carol, University of the District of Columbia. Institute of Gerontology. e United States. Administration on Aging., a cura di. A graduate program in gerontology at an HBCU: Final report. Washington, DC (4200 Conn. Ave., NW, Washington 20008): University of the District of Columbia, Institute of Gerontology, 1994.

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Capitoli di libri sul tema "HBCD"

Li, Yachen, Shuangyue Li, Xizhe Xie, Hang Xiu, Xiaohui Liu, Jing Shao e Xiuli Zhang. "Neuroprotection by Taurine on HBCD-Induced Apoptosis in PC12 Cells". In Advances in Experimental Medicine and Biology, 95–106. Dordrecht: Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-1079-2_9.

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Feitelson, Mark. "Anti-HBc". In Molecular Components of Hepatitis B Virus, 82–87. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4613-2573-4_6.

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Crawford II, Jerry. "Standard 1: HBCU Governance Challenges". In Journalism at Historically Black Colleges and Universities, 49–78. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97501-2_5.

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Jones, Sosanya M. "Reimagining HBCU Leaders as Policy Actors". In Examining Effective Practices at Minority-Serving Institutions, 95–112. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-16609-0_7.

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Jackson, Brandy, e Jacqueline Amparo. "HBCU Young Alumni: Paying It Forward". In Opportunities and Challenges at Historically Black Colleges and Universities, 89–103. New York: Palgrave Macmillan US, 2014. http://dx.doi.org/10.1057/9781137480415_7.

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Schexnider, Alvin J. "The HBCU Presidency: Challenges and Opportunities". In Saving Black Colleges, 137–57. New York: Palgrave Macmillan US, 2013. http://dx.doi.org/10.1057/9781137323460_7.

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Hall, Naomi M. "Sexual Health Promotion on HBCU Campuses". In Sexual Health and Black College Students, 103–11. New York: Routledge, 2022. http://dx.doi.org/10.4324/9781003180944-9.

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Huston, Erick K., e Joon Suk Lee. "Effects of Video Games on HBCU Students". In HCI International 2018 – Posters' Extended Abstracts, 51–58. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92285-0_8.

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Eckert, Claudia, e Klaus Wagner. "HBCI Meets OFX Integration zweier Internetbanking-Standards". In Sicherheitsinfrastrukturen, 122–34. Wiesbaden: Vieweg+Teubner Verlag, 1999. http://dx.doi.org/10.1007/978-3-322-89817-3_11.

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Diment, J. A., J. Tyrrell e J. Brown. "Measurement of anti-HBc IgM levels using the Amerlite anti-HBc IgM assay". In Chronically Evolving Viral Hepatitis, 122–23. Vienna: Springer Vienna, 1992. http://dx.doi.org/10.1007/978-3-7091-5633-9_26.

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Atti di convegni sul tema "HBCD"

Kim, Min-Seob, Sejin Park, Jiyoung Son, Wonchan Lee, Jongwoo Choi, Kyunghoon Shin e Minkyu Choi. "Trophic Structure and HBCD Biomagnification in a Marine Foodweb from Aquaculture Farm, South Korea". In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1310.

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Hsu, Jeff, Prashanth Mohan, Xiaofan Jiang, Jorge Ortiz, Sushant Shankar, Stephen Dawson-Haggerty e David Culler. "HBCI". In the 2nd ACM Workshop. New York, New York, USA: ACM Press, 2010. http://dx.doi.org/10.1145/1878431.1878444.

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Davis, Felicia. "BUILDING HBCU PATHWAYS TO GEOSCIENCES". In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-321004.

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Khan, M. Farrukh, e C. J. Tymczak. "Nascent HPC activities at an HBCU". In the 2011 TeraGrid Conference. New York, New York, USA: ACM Press, 2011. http://dx.doi.org/10.1145/2016741.2016798.

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Liu, Yuan, e J. Paul Siebert. "HBD: Hexagon-Based Binary Descriptors". In International Conference on Computer Vision Theory and Applications. SCITEPRESS - Science and Technology Publications, 2016. http://dx.doi.org/10.5220/0005720401750182.

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Addo, Sampson, Pawan Tyagi e Eva Mutunga. "Assessing Undergraduate Students’ Level of Awareness of Commercialization of Engineering Research Innovation at a Historically Black College and University". In ASME 2022 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/imece2022-95446.

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Abstract Engineering Research Innovation Commercialization (ERIC) seeks to translate products or services from the research laboratory to the marketplace or the end-user for societal benefit. Research indicates that universities have distinctive capabilities that allow them to play an important role in the process of research innovation commercialization. Historically Black Colleges and Universities (HBCUs), though originally established mainly as teaching and blue-collar trade institutions to educate African Americans, have been gradually commercializing several research innovations through patenting. However, this is significantly lower compared to that of their counterparts (specifically, Predominately White Institutions – PWIs). This according to available research is mainly because HBCUs have been traditionally under-served and under-resourced. Currently several programs such as the National Science Foundation (NSF) I-Corps and National Science Foundation Center of Research Excellence in Science and Technology (NSF-CREST) Center for Nanotechnology Research and Education (CNRE)) are being implemented by HBCUs to promote the commercialization of research innovations by training innovators about commercializing innovations. However, little research has been done to assess the level of awareness of engineering undergraduate students at an HBCU about the commercialization of engineering research innovations. This pilot study, therefore, seeks to investigate the level of awareness of engineering undergraduate students at an HBCU about engineering research innovation commercialization. The authors of this study have conducted a similar study that focused only on engineering graduate students in an HBCU. To achieve the purpose of this study, we developed a survey that adopts both binary and ordinal scales of question and administered it to 30 engineering undergraduate students in an ABET-accredited HBCU. After collation and analysis, the results indicate a low level of awareness of engineering research innovation commercialization by engineering undergraduate students at this University. Though at a pilot stage (to be validated by a larger study in different HBCUs), the study recommends that HBCUs initiate new or strengthen ongoing innovation commercialization training programs by including it in undergraduate engineering first-year courses such as “Introduction to Engineering” and related courses to help students become more aware of the opportunities in engineering research innovation commercialization processes.

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Hopkins, Patrick E., Richard N. Salaway, Robert J. Stevens e Pamela M. Norris. "Dependence of Thermal Boundary Conductance on Interfacial Mixing at the Chromium-Silicon Interface". In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15288.

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The thermal conductance at solid-solid interfaces is becoming increasingly important in thermal considerations dealing with devices on nanometer length scales. Specifically, interdiffusion or mixing around the interface, which is generally ignored, must be taken into account when the characteristic lengths of the devices are on the order of the thickness of this mixing region. To study the effect of this interfacial mixing on thermal conductance, a series of Cr films are grown on Si substrates subject to various deposition conditions to control the growth around the Cr/Si boundary. The Cr/Si interfaces are characterized with auger electron spectroscopy depth profiling. The thermal boundary conductance (hBD) is measured with the transient thermoreflectance technique. Values of hBD are found to vary with both the thickness of the mixing region and the rate of compositional change in the mixing region. The effects of the varying mixing regions in each sample on hBD are discussed and the results are compared to the diffuse mismatch model.

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Sousa, Adriany Brito, Cristhiane Campos Marques de Oliveira, Nicole Nogueira Cardoso, Luis Regagnan Dias, Carolina Barbosa Carvalho do Carmo, Marcos Filipe Bueno Langkamer, Fabiana Nunes de Carvalho Mariz e Carla Nunes de Araújo. "Serological profile of HBV infection among young adults assisted at a Counseling and Testing Centre in the southwest of Goiás". In XIII Congresso da Sociedade Brasileira de DST - IX Congresso Brasileiro de AIDS - IV Congresso Latino Americano de IST/HIV/AIDS. Zeppelini Editorial e Comunicação, 2021. http://dx.doi.org/10.5327/dst-2177-8264-202133p027.

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Introduction: Young people often present risky sexual behavior and are more exposed to hepatitis B virus (HBV) infection. Objective: The aim of this study was to describe the sexual behavior and HBV serological profile in the young population attended at a Counseling and Testing Centre (CTC) in the southwest of Goiás. Methods: Quantitative cross-sectional study with descriptive and retrospective analysis conducted at the CTC of Rio Verde. Data from young adults (18-29 years) attended in 2018 were examined to determine the seroprevalence and sexual behavior of HBV. Results: The sample consisted of 1,455 individuals, with 1,423 nonreactive for HBV (HBsAg and total anti-HBc negative), 2 with serological scar (total anti-HBc and anti-HBs positive), and 8 reagents (HBsAg and total anti-HBc positive). Of these, 63% (5) were males and 38% (3) females, with an average age of 24.6 years, 75% (6) were single, and a mean education of 4.25 years. The average number of sexual partnerships in the past 12 months was 2.71. Notably, 25% (2) had previous sexually transmitted infection (STI) and 75% (6) reported drug use, with alcohol being the most frequent. Regarding the use of condoms with fixed partnership, 57% (4) men did not use them. As reason for not wearing a condom, 71% (5) of them claimed trust in the sexual partnership. With casual partners, 14% (1) did not use condoms, 14% (1) justified their nonuse by trust, and 14% (1) were under the effect of drugs/alcohol. Conclusion: The prevalence of HBV in young adults who attended the CTC in 2018 was 0.55% with HBsAg and total anti-HBc positive and 0.14% with total anti-HBc and anti-HBs positive. Among those infected, most were single men, brown, with low education, and reported alcohol consumption and inconsistent use of condoms in sexual intercourse for both fixed and casual partnerships. These data reinforce the need for STI preventive strategies in this population.

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Garcia, Jorge, Fabio Giulii Capponi, Gabriele Borocci e Pablo Garcia. "Control strategy for Bidirectional HBCS Converter for supercapacitor applications". In 2014 IEEE 23rd International Symposium on Industrial Electronics (ISIE). IEEE, 2014. http://dx.doi.org/10.1109/isie.2014.6864887.

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Cady, Elizabeth T., e Norman L. Fortenberry. "Work in progress - strengthening HBCU engineering education research capacity". In 2007 37th annual frontiers in education conference - global engineering: knowledge without borders, opportunities without passports. IEEE, 2007. http://dx.doi.org/10.1109/fie.2007.4417834.

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Rapporti di organizzazioni sul tema "HBCD"

Collier, Geoffrey L. HBCU Undergraduate Research Fellowship. Fort Belvoir, VA: Defense Technical Information Center, marzo 2005. http://dx.doi.org/10.21236/ada431074.

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Kelly, John. HBCU Future Engineering Faculty Fellowship Program. Fort Belvoir, VA: Defense Technical Information Center, febbraio 2002. http://dx.doi.org/10.21236/ada399000.

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Monroe, Joseph. HBCU Future Engineering Faculty Fellowship Program. Fort Belvoir, VA: Defense Technical Information Center, marzo 2009. http://dx.doi.org/10.21236/ada494494.

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Tabibi, Bagher M., Dung X. Nguyen e Ja H. Lee. (HBCU) Thermal-Electric Propulsion With Magnetoplasmadynamic Acceleration. Fort Belvoir, VA: Defense Technical Information Center, gennaio 1998. http://dx.doi.org/10.21236/ada341315.

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Homan, Rick, e Catherine Searle. Programmatic implications of a cost study of home-based care programs in South Africa. Population Council, 2005. http://dx.doi.org/10.31899/hiv14.1001.

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The HIV/AIDS epidemic has meant that an increasing number of chronically ill people need ongoing assistance with care and support. Programs providing home-based care (HBC) services are a key component of the response to HIV/AIDS. However, few programs are using operations research, including cost studies, to decide what services to provide and how to structure their services. In 2004, the Horizons Program undertook a study of six HBC programs from different South African provinces to provide key information to NGOs, government ministries, donors, and the programs themselves to inform decisions about service delivery. The study analyzed the cost of HBC services, the best use of resources, and how well programs are able to meet the needs of beneficiaries and their families. The sample represents programs that operate in rural areas and informal settlements. This brief focuses on the coverage, organization, volume, and costs of the services and on findings from two of the methods of data collection: financial records and service statistics, and interviews with financial officers, program managers, and caregivers.

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Lubaroff, David M. Collaborative Undergraduate HBCU Student Summer Training Program Award. Fort Belvoir, VA: Defense Technical Information Center, giugno 2014. http://dx.doi.org/10.21236/ada610111.

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Brown-Simmons, Gloria, e Dianne Love. Center for Scientific Visualization (FY92/93 HBCU/MI). Fort Belvoir, VA: Defense Technical Information Center, settembre 1994. http://dx.doi.org/10.21236/ada299912.

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Lubaroff, David M. Collaborative Undergraduate HBCU Student Summer Training Program Award. Fort Belvoir, VA: Defense Technical Information Center, giugno 2012. http://dx.doi.org/10.21236/ada573370.

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Lubaroff, David M. Collaborative Undergraduate HBCU Student Summer Training Program Award. Fort Belvoir, VA: Defense Technical Information Center, giugno 2013. http://dx.doi.org/10.21236/ada590499.

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Lubaroff, David. Collaborative Undergraduate HBCU Student Summer Training Program Award. Fort Belvoir, VA: Defense Technical Information Center, giugno 2011. http://dx.doi.org/10.21236/ada553124.

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