Icosahedral Boron-Rich Solids as Refractory Semiconductors

1987 ◽  
Vol 97 ◽  
Author(s):  
David Emin
Keyword(s):  
High Temperature ◽  
Seebeck Coefficient ◽  
Basic Structure ◽  
Group Iv ◽  
Group Vi ◽  
Group V ◽  
Thermally Activated ◽  
Distinctive Structure ◽  
Wide Gap ◽  
P Type

ABSTRACTIcosahedral boron-rich solids are refractory materials composed of twelve-atom boron-rich icosahedral units with strong intericosahedral linkages. These distinctive structures admit unusual electronic and thermal transport properties. Here the distinctive (three-center) bonding which underlies these materials is first described. Then it is shown how insulators, semiconductors and highly degenerate (metal-like) materials emerge from the same basic structure with appropriate substitutions.The electronic transport of the boron carbides is then addressed. The boron carbides are degenerate p-type semiconductors in which the charge carriers are diamagnetically aligned pairs of electrons which hop between icosahedra. Uniquely, this thermally activated hopping conductivity increases with increasing hydrostatic pressure. However, the Seebeck coefficient (thermoelectric power) is uncharacteristic of a degenerate semiconductor. Namely, the Seebeck coefficient is typically both large and an increasing function of temperature. In addition, despite the hardness and refractory character of these materials, their thermal conductivities can be surprisingly low with a glass-like temperature dependence. These features are manifestations of the distinctive structure and bonding of these solids. In fact, this novel mix of properties makes the boron carbides exceptionally good very-high-temperature p-type thermoelectric materials.Icosahedral boron-rich solids have additional potential as high temperature semiconductors. In particular, the wide-gap icosahedral boronrich pnictides, B12P2 and B12As2, may be doped to form wide-gap refractory semiconductors. For example, replacement of the group V element with either a group VI or a group IV element is expected to yield n-type and ptype material, respectively.

scholarly journals Effect of a Diet Composed of Genetically Modified Feed Components on the Selected Immune Parameters in Pigs, Cattle, and Poultry

2013 ◽  
Vol 57 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Dariusz Bednarek ◽  
Katarzyna Dudek ◽  
Krzysztof Kwiatek ◽  
Małgorzata Świątkiewicz ◽  
Sylwester Świątkiewicz ◽  
...  
Keyword(s):  
Soybean Meal ◽  
Genetically Modified ◽  
Group Iv ◽  
Group Vi ◽  
Group V ◽  
Group Iii ◽  
Immune Parameters ◽  
Group I ◽  
Toxin Protein ◽  
Gm Soybean

Abstract The aim of the study was to evaluate the immune effects of genetically modified (GM), insect resistant corn (MON810) expressing toxin protein of Bacillus thuringiensis, and glyphosate-tolerant soybean meal (Roundup Ready MON-40-30-2), which are used as the feed mixture components in domestic animals. The study was conducted on 60 pigs (36 fatteners and 24 sows), 20 calves, 40 broilers, and 40 laying hens. Each species was divided into four basic nutritional groups: group I (control) - conventional feed, group II - feed consisted of GM soybean meal and non-modified corn, group III - non-modified soybean meal and GM corn, group IV - GM soybean meal and GM corn. Moreover, in the experiment on fatteners two additional groups were formed: group V - animals fed both conventional soybean meal and bruised grain, and group VI - GM soybean meal and conventional bruised grain. The results of study did not reveal any significant effect of feed mixtures containing GM components on the immune response in all animals regardless of their species and technological producing groups.

Generation of atomic group V materials for the p-type doping of wide gap II–VI semiconductors using a novel plasma cracker

1996 ◽  
Vol 161 (1-4) ◽  
pp. 86-89 ◽  
Author(s):  
H.-J. Lugauer ◽  
A. Waag ◽  
L. Worschech ◽  
W. Ossau ◽  
G. Landwehr
Keyword(s):  
Atomic Group ◽  
Group V ◽  
Wide Gap ◽  
P Type

scholarly journals Comparative Evaluation of Apical Sealing Ability of Different Obturation Techniques by Confocal Microscopy: An In Vitro Study

2020 ◽  
Vol 8 (02) ◽  
pp. 55-59
Author(s):  
Reetu Arora ◽  
Yogesh Kumar ◽  
Neetu Jindal ◽  
Renu Aggarwal ◽  
Kavneet Takhar
Keyword(s):  
Root Canal ◽  
Negative Control Group ◽  
Positive Control ◽  
Negative Control ◽  
Group Iv ◽  
Control Group ◽  
Group Vi ◽  
Group V ◽  
Group Iii ◽  
Group I

Abstract Introduction The aim of obturation in the root canal is to completely seal the canal space to eliminate all the portals of entry and exit between root canal and periodontal space. Various techniques have been developed to achieve a hermetic seal. Materials and Methods As many as 150 extracted human maxillary central incisors were taken for the study. Biomechanical preparation was done up to F5 protaper file. According to different obturation techniques, samples were divided into six groups, keeping 30 samples in experimental and 15 samples in control groups. Group I–Lateral Condensation, Group II–Thermafil, Group III–Beefill, Group IV–GuttaFlow, Group V–Positive Control group, Group VI–Negative Control group. After obturation, the samples were immersed in 2% Rhodamine-B dye for 24 hours. Each sample was longitudinally sectioned to examine under confocal laser scanning microscope. Statistical Analysis The results were evaluated with ANOVA and posthoc Tukey honest significant difference (HSD) comparison test. Results The mean values of dye penetration of different groups were Group I (Lateral Condensation) 1.51 ± 0.451, Group II (Thermafil) 0.918 ± 0.399, Group III (Beefill) 1.30 ± 0.559. Group IV (GuttaFlow) 0.655 ± 0.396, Group V (Positive Control group) 1.96 ±0.046, Group VI (Negative Control group) 0 ± 0. The lowest mean value of apical microleakage was found in GuttaFlow amongst all experimental groups. Conclusion It can be concluded that the GuttaFlow obturating material exhibited better apical sealing ability with canal walls.

Evidence for the role of PO4 deficiency in antihypertensive action of a high-Ca diet

1984 ◽  
Vol 246 (3) ◽  
pp. H324-H331 ◽  
Author(s):  
K. Lau ◽  
S. Chen ◽  
B. Eby
Keyword(s):  
Group Iv ◽  
Hypertensive Rats ◽  
Group Vi ◽  
Group V ◽  
Intact Group ◽  
Volume Contraction ◽  
Antihypertensive Action ◽  
Group I ◽  
Salutary Effect

Previous studies indicated a salutary effect of a high-Ca diet on high blood pressure (BP). The mechanism, however, is obscure. With balance and clearance techniques, the role of parathyroid hormone (PTH), volume contraction, hypercalcemia, and PO4 deficiency was evaluated in female spontaneous hypertensive rats (SHR). The antihypertensive effects of a high (4.3%) Ca diet in intact animals (groups I and II) could be reproduced in both 9- and 22-wk-old chronic stable parathyroidectomized (PTX) rats (groups III and IV), when compared with a low (0.22%) or normal (1.2%) CA diet. In both short (7 days) and long (12 wk) term exposure to the high-Ca diet, evidence for volume contraction could not be documented despite hypercalcemia sustained through the 12th wk (10.8 vs. 9.7 mg/100 ml, group I control, P less than 0.02). When produced by ip injections, chronic hypercalcemia of similar magnitudes as oral Ca supplements failed to reduce BP in either intact (group VI) or PTX (group IV) rats. Rats in group IV fed the high-Ca diet displayed marked hypophosphatemia (3.2 vs. 6.9 mg/100 ml), hypophosphaturia (0.15 vs. 15 mg/day), hypermagnesiuria (11 vs. 7.7 mg/day), and drastically reduced net intestinal PO4 absorption (13.3 +/- 7.5 vs. 66.8 +/- 7.5 mg/day) compared with rats fed 1.2% Ca diet. To test the PO4-deficiency hypothesis, additional SHR (group V) were fed either 1.2% Ca diet and injected ip with NaCl or fed 4.3% Ca diet, with half of these animals injected with neutral NaPO4 and half with NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Chemoprevention with green propolis green propolis extracted in L-lysine versus carcinogenesis promotion with L-lysine in N-Butyl-N-[4-hydroxybutyl] nitrosamine (BBN) induced rat bladder cancer

2012 ◽  
Vol 27 (2) ◽  
pp. 185-192 ◽  
Author(s):  
Conceição Aparecida Dornelas ◽  
Francisco Vagnaldo Fechine-Jamacaru ◽  
Irineu Lima Albuquerque ◽  
Hemerson Iury Ferreira Magalhães ◽  
Adjair Jairo Silva de Souza ◽  
...  
Keyword(s):  
Group Iv ◽  
The Other ◽  
Control Group ◽  
Group Viii ◽  
Group Vi ◽  
Group V ◽  
Induction Group ◽  
Rat Bladder ◽  
Bladder Carcinogenesis ◽  
Group I

PURPOSE: To determine the effects of green propolis extracted in L-lysine (WSDP) and of L- lysine for 40 weeks on induced rat bladder carcinogenesis. METHODS: The animals (groups I, II, III, IV, V and VI) received BBN during 14 weeks. Group I was treated with propolis 30 days prior received BBN, and then these animals were treated daily with propolis; Groups II and III was treated with subcutaneous and oral propolis (respectively) concurrently with BBN. The animals of Group IV were treated L-lysine; Group V received water subcutaneous; and Group VI received only to BBN. Among the animals not submitted to carcinogenesis induction, Group VII received propolis, Group VIII received L-lysine and Group IX received water. RESULTS: The carcinoma incidence in Group I was lower than that of control (Group VI). The carcinoma multiplicity in Group IV was greater than in Group VI. All animals treated with L-lysine developed carcinomas, and they were also more invasive in Group IV than in controls. On the other hand, Group VIII showed no bladder lesions. CONCLUSION: The WSDP is chemopreventive against rat bladder carcinogenesis, if administered 30 days prior to BBN , and that L-lysine causes promotion of bladder carcinogenesis.

From the Mystery to the Understanding of the Self-Interstitials in Silicon

1980 ◽  
Vol 2 ◽  
Author(s):  
W. Frank ◽  
A. Seeger ◽  
U. Gösele
Keyword(s):  
High Temperature ◽  
The Self ◽  
Experimental Conditions ◽  
Group V ◽  
Group Iii ◽  
Enhanced Diffusion ◽  
Self Diffusion ◽  
Thermally Activated ◽  
Temperature Equilibrium ◽  
K Concentration

ABSTRACTOur present knowledge on self-interstitials in silicon and the rôle these defects play under widely different experimental conditions are surveyed. In particular, the following phenomena involving self-interstitials either in supersaturations or under high-temperature thermal-equilibrium conditions are considered: mobility-enhanced diffusion of self-interstitials below liquid-helium temperature, thermally activated diffusion of self-interstitials at inter-mediate temperatures (14O K to 600 K), concentration-enhanced diffusion of Group-III or Group-V elements in silicon at higher temperatures, and— as examples for high-temperature equilibrium phenomena — self-diffusion and diffusion of gold in silicon. This leads to the picture that the self-interstitials in silicon may occur in different electrical charge states and possess dumbbell configurations or are extended over several atomic volumes at intermediate or high temperatures, respectively.

scholarly journals Estimation of vitamin C human protective dose for acetaminophen toxicity, using acute animal toxicity study

2017 ◽  
Vol 2 (2) ◽  
pp. 101-105 ◽  
Author(s):  
Mudhaffar I. Al-Farras ◽  
Khalid K. Abdul-Razzak ◽  
Mohammed Yacoub ◽  
Wael M. Hananeh
Keyword(s):  
Mortality Rate ◽  
Vitamin C ◽  
Lethal Dose ◽  
Group Iv ◽  
Group Vi ◽  
Group V ◽  
Liver Histopathology ◽  
Toxic Damage ◽  
Group I ◽  
Group Ii

Acetaminophen (APAP) is the main cause of fulminant hepatic failure. Vitamin C is a natural antioxidant with protective potentials against APAP toxic damage. In this animal study, and after an LD50 determination and selection of suitable lethal dose, the investigation was done to select a proper protective dose of vitamin C against lethal APAP dose. All 6 animal groups received a lethal dose of APAP (3250 mg/kg), group II, III and IV received 500, 1000 and 1500 mg/kg vitamin C respectively, group V received 1200 mg/kg N-Acetylcysteine (NAC), and group VI receive 1000 mg/kg vitamin C and 1200 mg/kg NAC. Mortality was recorded and liver histopathology was carried out. The results showed, the mortality rate in the group I was 68.75% and 37.5%, 31.25% in group II and III respectively, while group IV Showed a higher mortality rate and in group V and VI it was 25%. There was also a gradual reduction in the grade of histopathological damage in all groups, ranging from 2.4 ± 0.55 in group I to 0.4 ± 0.55 in group V and VI. In conclusion, vitamin C showed an increasing reduction in mortality and more histopathological protection, and it was more significant at 1000 mg/kg. NAC adds no more protection or reduction in mortality. The estimated protective dose of vitamin C was 700 to1127 mg for each gram of APAP. Incorporation of this dose of vitamin C with APAP preparations may be considered as a promising method for reducing mortality or severity of APAP intoxication.

ВЗАИМОСВЯЗЬ ПРОДУКТИВНЫХ ПОКАЗАТЕЛЕЙ КОРОВ ЧЕРНО-ПЕСТРОЙ ПОРОДЫ С ВОСПРОИЗВОДИТЕЛЬНЫМИ КАЧЕСТВАМИ

2019 ◽  
pp. 39-42
Author(s):  
G.Yu. BEREZKINA ◽  
S.L. VOROBYEVA ◽  
E.M. KISLYAKOVA ◽  
A.A. KOREPANOVA
Keyword(s):  
Experimental Studies ◽  
Live Weight ◽  
Group Iv ◽  
Reproductive Capacity ◽  
Group Vi ◽  
Group V ◽  
Group Iii ◽  
Group I ◽  
The Republic ◽  
Breeding Farms

Изучено влияние возраста и живой массы при первом осеменении на воспроизводительные качества коровпервотелок чернопестрой породы в племенных заводах Удмуртской Республики. Исследования проводились в период с 2015 по 2018 гг. Для проведения исследований были сформированы 6 групп животных в зависимости от возраста первого осеменения. В I группу вошли коровы с возрастом первого осеменения до 13 мес, во II от 13,1 до 15 мес, в III от 15,1 до 17, в IV от 17,1 до 19, в V от 19,1 до 21 и в VI группу от 21 мес и старше. При этом живая масса телок в I группе в среднем составила 349,5 кг, во II 370,9, в III 387,7, в IV 400,2, в V 420,7 и в VI группе 440,2 кг. Анализ возраста первого осеменения в племенных хозяйствах республики показал, что средний возраст плодотворного осеменения в 2018 году составил 17,0 мес. с живой массой 394 кг. По результатам экспериментальных исследований нами получено, что лучшие воспроизводительные показатели и молочная продуктивность выявлена у коровпервотелок, которых осеменяли в возрасте 14,6 мес. В данной группе продолжительность сервиспериода составила 127,3 дня, коэффициент воспроизводительной способности 0,90, выход телят на 100 коров составил более 85,3. Удой за 305 дней лактации, у коровпервотелок второй опытной группы составил 6332,3 кг с массовой долей жира 3,65 и белка 3,15 .The influence of age and live weight at the first insemination on reproductive qualities of cowsborn black and white breed in breeding farms of the Udmurt Republic was studied. The studies were conducted between 2015 and 2018. For the research 6 groups of animals were formed depending on the age of the first insemination. Group I included cows with the age of first insemination up to 13 months, in group II from 13.1 to 15 months, in III group from 15.1 to 17 months, in group IV from 17.1 to 19 months, in group V from 19.1 to 21 months and in VI group from 21 months and more. At the same time, the live weight of heifers in group I averaged 349.5 kg, in group II370.9 kg, in group III 387.7 kg, in group IV 400.2 kg, in group V 420.7 kg and in group VI 440.2 kg. The analysis of the age of the first insemination in breeding farms of the Republic showed that the average age of fruitful insemination in 2018 was 17.0 months with a live weight of 394 kg. According to the results of experimental studies, we obtained that the best reproductive performance and milk productivity was revealed in cows, which were inseminated at the age of 14.6 months. In this group, the duration of the service period was 127.3 days, the coefficient of reproductive capacity 0.90, yield of calves per 100 cows. Milk yield for 305 days of lactation, in cows of the second experimental group was 6332.3 kg with a mass fraction of fat 3.65 and protein 3.15.

Synthesis and High Temperature Thermoelectric Properties of Alkaline-Earth Metal Hexaborides MB6 (M=Ca, Sr, Ba)

2003 ◽  
Vol 793 ◽  
Author(s):  
Masatoshi Takeda ◽  
Yosuke Kurita ◽  
Keisuke Yokoyama ◽  
Takahiro Miura ◽  
Tsuneo Suzuki ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Thermoelectric Device ◽  
Alloying Effect ◽  
P Type

ABSTRACTPolycrystalline alkaline-earth hexaborides (MB6: M =Ca, Sr, Ba) were synthesized and their thermoelectric and transport properties were examined to discuss their possibility as high temperature thermoelectric materials. Hall measurements showed that carrier concentration of the BaB6 was the highest among the three hexaborides and that of CaB6 was the lowest. Substitution of part of the alkaline earth metals with one of the others changed the carrier concentration of the hexaboride. As the carrier concentration increased, Seebeck coefficient increased and electrical conductivity decreased. These results suggest that the thermoelectric properties of the divalent hexaborides depend largely on the carrier concentration, and optimum carrier concentration which gives maximum power factor was estimated to be approximately 2x1026 m−3. Consequently, such a substitution enables us to control Seebeck coefficient and electrical conductivity of the hexaborides, and will also be effective to reduce the lattice heat conduction due to the alloying effect. A thermoelectric device was fabricated using SrB6 and boron carbide thin films as n-type and p-type elements, respectively. To the best of our knowledge, this is the first demonstration of a thermoelectric device composed of only boron-rich solids.

High Temperature Thermoelectric Properties of Boron Carbide

1991 ◽  
Vol 234 ◽  
Author(s):  
T. L. Aselage
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermoelectric Properties ◽  
Power Conversion ◽  
Unusual Structure ◽  
Thermally Activated ◽  
Structure And Bonding ◽  
Increasing Temperature ◽  
P Type ◽  
Very High

ABSTRACTBoron carbides are refractory solids with potential for application as very high temperature p-type thermoelectrics in power conversion applications. The thermoelectric properties of boron carbides are unconventional. In particular, the electrical conductivity is consistent with the thermally activated hopping of a high density (≈ 1021/cm3) of bipolarons; the Seebeck coefficient is anomalously large and increases with increasing temperature; and the thermal conductivity is surprisingly low. In this paper, these unusual properties and their relationship to the unusual structure and bonding present in boron carbides are reviewed. Finally, the potential for utilization of boron carbides at very high temperatures (up to 2200°C) and for preparing n-type materials is discussed.

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