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1.
An ab initio computational density functional theory (DFT) was used to study the formation of the first cyclic molecule (phenyl)
initiated by the ethynyl radical (C2H•). The study covers a competition reaction between the addition reactions of C2H• with ethyne (C2H2) and some molecular re-arrangement schemes. The minimum energy paths of the preferred cyclic formation route were characterized.
A thorough thermochemical analysis was performed by evaluating the differences in the energy of activation (ΔE), enthalpy
(ΔH), and Gibb's free energy (ΔG) of the optimized stable and transition state (TS) molecules. The reaction temperatures were
set to normal (T = 298 K) and combustion (T = 1,200 K) conditions.
相似文献
Romero M. SantiagoEmail: |
2.
Excessive Zn but normal Cu and Mg in the staple food consumed by the people of Chandigarh (Union territory and capital of
Punjab and Haryana States of India) has been considered to be the major risk factor for the prevalence of obesity (33.15%)
and obesity-related diseases in this region. Therefore, in the present investigations, in obesity-related diseases, the status
of these minerals was estimated in their tissues, including hair, nails, and blood serum and urine, and compared with those
of normal subjects. They were grouped as: normal subjects in control Group A, middle-aged diabetics in Group DM, older diabetics in Group DO, and diabetics with osteoarthritis in Group D+ OA, osteoarthritis in Group OA and rheumatoid arthritis in Group RA, respectively.
The results evaluated in the order as: hair Zn, group D+OA>DM>OA>A (control)>RA>DO (p < 0.001); hair Cu, group A (control)>DM>OA>D+OA>DO>RA (p < 0.001); hair Mg, group A (control)>DM>OA>D+OA>RA>DO (p < 0.001, 0.01); hair Mn, group A (control)>RA>OA>D-OA>DM>DO (p < 0.001); nail Zn, group DM>D+OA>OA>A (control)>RA>DO (p < 0.001, 0.05); nail Cu, group A (control)>OA>DM>D+OA>RA>DO (p < 0.001); nail Mg, group A (control)>OA>DM>DO>D+OA >RA (p < 0.001); nail Mn, group A (control) >RA>OA>D+OA>DM>DO (p < 0.01); urine Zn, group DO>DM>D+OA>A (control)>RA>OA (p < 0.01); urine Cu, group RA>D+OA>DO>OA> DM>A (control) (p<0.001); urine Mg, group RA>OA>D+OA>DO>DM>A (control; p < 0.001); urine Mn, group DO>DM>OA>D+OA>RA>A (control; p < 0.001), respectively. The analysis of the mineral status in serum of diabetics further showed their highly significant
rise from lower mean age subgroup to higher mean age subgroup than their control counter parts (p < 0.001, 0.01, and 0.05) with coincident deficiencies of Cu, Mg, and Mn in their tissues. This study would be helpful considering
the status of minerals in these obesity-related diseases depending on the choice of the food consumed to improve the quality
of life and prognosis for the diseases. 相似文献
3.
Lévy Flights in Dobe Ju/’hoansi Foraging Patterns 总被引:1,自引:0,他引:1
Clifford T. Brown Larry S. Liebovitch Rachel Glendon 《Human ecology: an interdisciplinary journal》2007,35(1):129-138
We analyzed data on Ju/’hoansi hunter–gatherer foraging patterns and found that their movements between residence camps can
be modeled as a Lévy flight. The step lengths of their movements scale as a power law with an exponent μ = 1.97. Their wait times (residence times) at the camps also scale as a power law (μ = 1.45). A Lévy flight with step lengths μ = 2 is an optimal search pattern for scarce, randomly located targets; thus, the Ju/’hoansi foraging pattern may approach
an optimal search in this area of sparse plant and animal resources. These findings affect the application of optimal foraging
theory to humans in anthropology and archaeology because they alter the way in which search and travel times should be quantified.
These results may also carry implications for the study of other patterns of human movement, such as demic diffusion and migration.
相似文献
Clifford T. BrownEmail: |
4.
Analytical modeling techniques can be used to study the performance of optical multistage interconnection network (OMIN) effectively.
MINs have assumed importance in recent times, because of their cost-effectiveness. An N×N MIN consists of a mapping from N processors to N memories, with log 2
N stages of 2×2 switches with N/2 switches per stage. The interest is on the study of the performance of unbuffered optical multistage interconnection network
using the banyan network. The uniform reference model approach is assumed for the purpose of analysis. In this paper the analytical
modeling approach is applied to an N×N OMIN with limited crosstalk (conflicts between messages) up to (log 2
N−1). Messages with switch conflicts satisfying the constraint of (log 2
N−1) are allowed to pass in the same group, but in case of a link conflict, the message is routed in a different group. The
analysis is performed by calculating the bandwidth and throughput of the network operating under a load l and allowing random traffic and using a greedy routing strategy. A number of equations are derived using the theory of probability
and the performance curves are plotted. The results obtained show that the performance of the network improves by allowing
limited crosstalk in the network.
相似文献
Yi PanEmail: |
5.
Alma R. López-Laredo Fanny D. Ramírez-Flores Gabriela Sepúlveda-Jiménez Gabriela Trejo-Tapia 《In vitro cellular & developmental biology. Plant》2009,45(5):550-558
Tecoma stans is a tropical plant from the Americas. Antioxidant activity and both phenolic compound and flavonoid total content were determined
for callus tissue of T. stans cultured in either a set photoperiod or in darkness. Callus lines from three explant types (hypocotyls, stem, and leaf) were
established on B5 culture medium supplemented with 0.5 μM 2,4-D and 5.0 μM kinetin. While leaf-derived callus grew slower
under a 16-h photoperiod (specific growth rate, μ = 0.179 d−1, t
D = 3.9 d) than in darkness (μ = 0.236 d−1, t
D = 2.9 d), it accumulated the highest amount (p < 0.05) of both phenolics (86.6 ± 0.01 mg gallic acid equivalents/g) and flavonoids (339.6 ± 0.06 mg catechin equivalents/g).
Similarly, antioxidant activity was significantly higher (p < 0.05) when callus was cultured in period light than when grown in extended darkness. Antioxidant activity measured with
a 2,20-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS)-based assay was 350.5 ± 15.8 mmol Trolox/g
extract for callus cultured under a defined photoperiod compared to 129.1 ± 7.5 mmol Trolox/g extract from callus cultured
in darkness. Content of phenolic compounds and flavonoids was in agreement with a better antioxidant power (EC50 = 450 μg extract/mg 1,1-diphenyl-2-picrylhydrazyl) and antiradical efficiency. Results of the present study show that calli
of T. stans are a source of compounds with antioxidant activity that is favored by culture under a set photoperiod. 相似文献
6.
N. J. Adams B. Pinshow L. Z. Gannes H. Biebach 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(3):195-199
We examined the relationship between body temperature (Tb) of free flying pigeons and ambient water vapor pressure and temperature. Core or near core Tb of pigeons were measured using thermistors inserted into the cloaca and connected to small transmitters mounted on the tail
feathers of free flying tippler pigeons (Columba livia). Wet and dry bulb temperatures were measured using modified transmitters mounted onto free-flying pigeons. These allowed
calculation of relative humidity and hence water vapor pressure at flight altitudes. Mean Tb during flight was 42.0 ± 1.3 °C (n = 16). Paired comparisons of a subset of this data indicated that average in-flight Tb increased significantly by 1.2 ± 0.7 °C (n = 7) over that of birds at rest (t = −4.22, P < 0.05, n = 7) within the first 15 min of takeoff. In addition, there was a small but significant increase in Tb with increasing ambient air (Ta) when individuals on replicate flights (n = 35) were considered. Inclusion of water vapor pressure into the regression model did not improve the correlation between
body temperature and ambient conditions. Flight Tb also increased a small (0.5 °C) but significant amount (t = 2.827, P < 0.05, n = 8) from the beginning to the end of a flight. The small response of Tb to changing flight conditions presumably reflects the efficiency of convection as a heat loss mechanism during sustained
regular flight. The increase in Tb on landing that occurred in some birds was a probable consequence of a sudden reduction in convective heat loss.
Accepted: 2 February 1999 相似文献
7.
Since 1985, China has established three breeding herds of Père David’s deer: the Beijing Père David’s Deer Park (39°07′N,
116°03′E), the Dafeng Père David’s Deer Nature Reserve (33°05′N, 120°49′E) and Shishou (Tianezhou) Père David’s Deer Nature
Reserve (29°49′N, 112°33′E), through reintroductions of about 30–40 founders. Since establishment, all three populations have
grown steadily. However, genetic backgrounds in those populations are still unknown. We studied the genetic diversity in Père
David’s deer and genetic consequences of population relocations in China. We revealed that genetic diversity was extremely
low in Père David’s deer populations in China. Only a single mtDNA D-loop haplotype was found in the deer, furthermore, only
five polymorphic microsatellite loci were screened out from 84 pairs of species-transferred primers. Genetic makeup in the
three Père David’s deer populations were significantly different (P < 0.01). H
E and allelic richness in the Tianezhou population were the highest (0.54, 2.60, n = 31), Beijing population (0.52, 2.4, n = 125) showed the second highest measures, while the Dafeng population (0.46, 2.39, n = 39) measured lowest. Our results suggest that effective management of a species of low genetic diversity like the Père
David’s deer should consider the genetic background of each founder to make sure genetic variations are preserved in both
source population and relocated population. Now, the Tianezhou population is the most appropriate source population in China
when establishing new Père David deer populations in the wild.
相似文献
Zhigang JiangEmail: |
8.
To compare the effect of IV magnesium with other antihypertensives in emergency department (ED) patients with hypertension.
ED patients with a systolic BP > 135 mmHg or diastolic BP > 85 were approached for entry into the study. Those granting consent
were randomly placed into one of three treatment groups: (1) 1.5 gm IV MgSO4 (n = 42), (2) a parenteral or oral antihypertensive agent (n = 41), (3) both IV MgSO4 and an antihypertensive agent (n = 44). Systolic and diastolic blood pressures were measured at entry into the study and at 15, 30, 45, and 60 min after magnesium
or other antihypertensive medications were given. The main outcome measure was blood pressure at 60 min, and results were
compared using one-way analysis of variance with the post hoc Tukey HSD test. Compared to systolic and diastolic blood pressures
at time 0, both were lower at 15, 30, 45, and 60 min in all groups (p < 0.05). No significant difference in systolic or diastolic BP at any time point was observed when response to treatment
was compared between the three groups. Intravenous MgSO4 is as effective as antihypertensives at lowering BP in emergency department patients. 相似文献
9.
Ivana Zucchetti Rosaria De Santis Simona Grusea Pierre Pontarotti Louis Du Pasquier 《Immunogenetics》2009,61(6):463-481
Two selected receptor genes of the immunoglobulin superfamily (IgSF), one CTX/JAM family member, and one poliovirus receptor-like
nectin that have features of adhesion molecules can be expressed by Ciona hemocytes, the effectors of immunity. They can also be expressed in the nervous system (CTX/JAM) and in the ovary (nectin).
The genes encoding these receptors are located among one set of genes, spread over Ciona chromosomes 4 and 10, and containing other IgSF members homologous to those encoded by genes present in a tetrad of human
(1, 3 + X, 11, 21 + 19q) or bird chromosomes (1, 4, 24, 31) that include the leukocyte receptor complex. It is proposed that
this tetrad is due to the two rounds of duplication that affected a single prevertebrate ancestral region containing a primordial
leukocyte receptor complex involved in immunity and other developmental regulatory functions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Rosaria De Santis (Corresponding author)Email: |
10.
Ayoub A. Mohamed Abdel Aziem A. Ali Naji I. Ali Elshafaee H. Abusalama Mustafa I. Elbashir Ishag Adam 《Biological trace element research》2011,140(3):284-290
The study was conducted to investigate determinants (clinical, nutritional, and nonnutritional factors) of anemia among pregnant
women in Kassala, eastern Sudan. Sociodemographic characteristics were gathered; serum ferritin, zinc, albumin, and C-reactive
protein were measured using different laboratory methods in a cross-sectional study of 250 pregnant women. Of the 250 women,
58.4% had anemia (hemoglobin (HB) <11 g/dl), 6.8% had severe anemia (HB < 7 g/dl), 19.6% had iron deficiency (S-ferritin <15 μg/l),
14.8% had iron deficiency anemia (<11 g/dl and S-ferritin <15 μg/l), and 38% had zinc deficiency (<80 μg/ml). S-albumin, zinc,
and ferritin were significantly lower in patients with severe anemia. While age, gestational age, ferritin, and C-reactive
protein were not predictors for anemia, primigravidae (OR = 2.7, 95% CI = 1.1–6.7, P = 0.02), low S-albumin (OR = 5.9, 95% CI = 1.4–25.2, P = 0.01), and low S-zinc (OR = 2.6, 95% CI = 1.0–6.6, P = 0.03) were the predictors for anemia. While there was no significant correlation between hemoglobin, S-zinc, and S-ferritin,
there was a significant positive correlation between hemoglobin and S-albumin (r = 0.308, P = 0.001) and significant inverse correlation between hemoglobin and C-reactive protein (r = 0.169, P = 0.007). Thus, the role of chronic inflammation and zinc as possible contributing factors to anemia in pregnancy has important
implications for the clinical evaluation and treatment of these women. 相似文献
11.
Chengtai Yang Ling Cao Weimin Wang Yi Yang Khalid Abbas Binlun Yan Hanping Wang Li Su Yuhua Sun Huanling Wang 《Environmental Biology of Fishes》2009,86(1):145-153
To obtain the phylogenetic relationship between diploid and tetraploid Misgurnus anguillicaudatus, the mitochondrial cyt b gene in the diploid and tetraploid weather loach were isolated and sequenced. The DNA sequences were analyzed using MEGA
3.0 software to determine the phylogenetic relationship. Forty-five variable sites among cyt b gene sequences and 18 amino acid substitutions occurred within the diploid and tetraploid loaches as deduced from the nucleotide
sequences analysis of the cyt b gene. The nucleotide pairwise distance between diploid and tetraploid loach ranged from 0.001 to 0.025. Phylogenetic analysis
revealed evolutionary relationships between diploid and tetraploid loach. Our results indicated a significant difference between
diploid and tetraploid loach about the cyt b gene. AMOVA analysis indicated that there were no significant genetic variations within diploid loaches (Fst = 0.2529, P > 0.05) and within tetraploid loaches (Fst = 0.0564, P > 0.05), neither. However, significant genetic differences were found between diploid and tetraploid loaches (Fst = 0.7634,
P < 0.05). Thus, it is concluded that no reproductive isolation was found within the same cytotypes of different localities,
but there was reproductive isolation between these two cytotypes. The diploid loach existed before the tetraploid loach in
nature. The present study is the first to describe the phylogenetic relationships of natural polyploidy weather loach using
mtDNA cyt b gene. 相似文献
12.
Toghyani M Toghyani M Shivazad M Gheisari A Bahadoran R 《Biological trace element research》2012,146(2):171-180
This study was conducted to determine the effects of dietary supplementation with Cr nicotinate and Cr chloride and their
optimum inclusion rate on performance, carcass traits, meat oxidative stability, serum metabolites, hematological parameters,
and liver chromium concentration in heat-stressed broilers. A total number of 420, 1-day-old male broiler chicks were randomly
assigned to seven treatments with four replicates of 15 chicks. The dietary treatments consisted of the basal diet supplemented
with 0 (control), 500, 1,000, and 1,500 μg/kg Cr in the form of Cr nicotinate and Cr chloride. Chicks were raised for 6 weeks
in heat stress condition (33 ± 2°C). Supplements of organic and inorganic Cr particularly at 1,500 μg/kg incorporation increased
feed consumption (P < 0.05) and body mass gain of broilers (P < 0.01). Cr supplementation increased carcass yield and decreased abdominal fat (P < 0.01). Supplementation of 1,500 μg/kg Cr nicotinate (P < 0.05) enhanced liver Cr concentration. Storage time increased lipid oxidation of meat (P < 0.01). Cr decreased lipid oxidation of breast and thigh muscles over 2 (P < 0.01) or 6 (P < 0.05) days of storage time. Birds fed 1,500 μg/kg Cr nicotinate, had lower concentration of serum glucose and triglyceride
at 21 days (P < 0.05). Hematological parameters tested at 21 and 42 days, were not influenced. The results suggested that dietary Cr supplementation
regardless of its source have a positive effect on productive, and carcass traits, also enhances oxidative stability of refrigerated
meat in broilers reared under heat stress conditions. 相似文献
13.
Borzyszkowska J Stanislawska-Sachadyn A Wirtwein M Sobiczewski W Ciecwierz D Targonski R Gruchala M Rynkiewicz A Limon J 《Journal of applied genetics》2012,53(2):175-182
This study examines whether renin-angiotensin-aldosterone system gene polymorphisms: ACE (encoding for angiotensin converting enzyme) c.2306-117_404 I/D, AGTR1 (encoding for angiotensin II type-1 receptor) c.1080*86A>C and CYP11B2 (encoding for aldosterone synthase) c.-344C>T are associated with the extension of coronary atherosclerosis in a group of
647 patients who underwent elective coronary angiography. The extension of CAD was evaluated using the Gensini score. The
polymorphisms were determined by PCR and RFLP assays. The associations between genotypes and the extent of coronary atherosclerosis
were tested by the Kruskal-Wallis test, followed by pairwise comparisons using Wilcoxon test. The population has been divided
into groups defined by: sex, smoking habit, past myocardial infarction, BMI (>, ≤ 25), age (>, ≤ 55), diabetes mellitus, level
of total cholesterol (>, ≤ 200 mg/dl), LDL cholesterol (>, ≤ 130 mg/dl), HDL cholesterol (>, ≤ 40 mg/dl), triglycerides (>,
≤ 150 mg/dl). Significant associations between the ACE c.2306-117_404 I/D polymorphism and the Gensini score in men with high total cholesterol levels (PKruskal-Wallis = 0.008; Padjusted = 0.009), high level of LDL cholesterol (PKruskal-Wallis = 0.016; Padjusted = 0.028) and low level of HDL cholesterol (PKruskal-Wallis = 0.04; Padjusted = 0.055) have been found. No association between the AGTR1 c.1080*86A>C and CYP11B2 c.-344C>T and the Gensini score has been found. These results suggest that men who carry ACE c.2306-117_404 DD genotype and have high total cholesterol, high LDL cholesterol and low HDL cholesterol levels may be predisposed
to the development of more severe CAD. 相似文献
14.
Lughaidh Ó Néill Tijmen Veldhuizen Addy de Jongh John Rochford 《European Journal of Wildlife Research》2009,55(4):363-370
We examined the spatial structure and socio-biology of a native wild population of Eurasian otters (Lutra lutra) on mesotrophic rivers in a mild temperate climate. Radio-tracking of 20 individuals revealed exclusive intra-sexual adult
home-ranges. Adult female home-ranges (7.5 km, SD = 1.5 km, n = 7) were inversely related to river width (, F
6 = 13.5, P = 0.014) and so appeared to be based on food resources. The aquatic area within adult male home-ranges (30.2 ha, SD = 9.5 ha,
n = 5) was greater than that within adult female’s (16.8 ha, SD = 7.0 ha) (t
10 = 2.437, P = 0.035), though this result is inconclusive because some males were tracked on oligotrophic rivers. One adult male expanded
its range from 10.2 km to 19.3 km within 5 days of the death of the neighbouring male, suggesting that male home-ranges were
heavily influenced by conspecifics. 相似文献
15.
The aim of the present study was to assess the degree of genetic variation and divergence among six populations of Calomys hummelincki, a phyllotine rodent distributed in northern South America. With this information we will try to evaluate the two hypotheses
of possible colonization and differentiation of this group of rodents postulated by Baskin and Reig. We studied 34 loci by
electrophoretic analysis: 21 were monomorphic for all populations and 13 were polymorphic in at least one population, being
P
1% = 21.6% the mean value for all populations. The mean value of heterozygosity per locus was H = 0.075. Low values of genetic distance were observed among populations of the Llanos region (0.001 < D < 0.006). There was a larger genetic distance (D = 0.024) between the population from Isiro, in the northwestern semiarid region, and those from the Llanos region. The insular
population of Aruba displayed the lowest value of genetic distance with the population from Isiro (D = 0.014). The specimens from Sipao, on the right side of the Orinoco river, displayed the highest values of genetic distances
in comparison with other populations of C. hummelincki (0.070 < D < 0.095). The relatively high differentiation was due to the fixation of new alleles, not found in other populations of C. hummelincki, at loci Idh-1 and Est-2. F-statistics and Nm values indicated reduced gene flow among the populations sampled. Despite the limited data, the results
seem to support Reig's hypothesis about south to north colonization of genus Calomys in South America.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Nucleotide variation at several cold candidate genes including seven members of the dehydrin gene family was surveyed in haplotypes
of Scots pine (Pinus sylvestris) sampled in populations showing divergence for cold tolerance in Europe. Patterns of nucleotide diversity, linkage disequilibrium,
and frequency spectrum of alleles were compared between north and south populations to search for signs of directional selection
potentially underlying adaptation to cold. Significant differentiation between populations in allelic frequency or haplotype
structure was detected at dhn1, dhn3, and abaH loci. Allelic dimorphism with no evidence of haplotype clustering by geographical distribution was found at dhn9. An excess of fixed non-synonymous mutations as compared to the outgroup P. pinaster pine species was found at dhn1. Differences in nucleotide polymorphisms were found between the members of the Kn class of dehydrin upregulated during cold
acclimation (average πsil = 0.004) as compared to the SKn class (average πsil = 0.024). The multilocus nucleotide diversity at silent sites (θ
W = 0.009) was moderate compared to other conifer species, but higher than previous estimates for Scots pine. There was an
excess of rare and high frequency derived variants as revealed by significantly negative multilocus value of Tajima’s D (D = −0.72, P < 0.01) and negative mean value of Fay and Wu H statistics (H = −0.50). The level of linkage disequilibrium decayed rapidly with an average expected r
2 of 0.2 at about 200 bp. Overall, there was a positive correlation between polymorphism and divergence at ten loci when outgroup
sequence was available. The discovered polymorphism will be used for further evaluation of the adaptive role of genes through
association mapping studies.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Elongate loach (Leptobotia elongata (Bleeker)), an endemic fish species to China, is a famous ornamental freshwater fish. Here, a comparative study of mtDNA
control region (D-loop) (835 bp) sequences was performed to analyze its wild population structure and evaluate the genetic
diversity for 110 individuals from five locations in the upper reaches of the Yangtze River, China. A total of 49 polymorphic
sites and 45 haplotypes yielded high haplotype diversity (h = 0.952), but low nucleotide diversity (π = 0.00454) as that of many fish species. Sequence divergences between haplotypes ranged from 0.0033 ± 0.0011 to 0.0050 ± 0.0012
in intra-groups, and from 0.0037 ± 0.0.0011 to 0.0050 ± 0.0012 between groups. Significant values of Tajima’s D (−1.86383, P < 0.01) and Fu’s F
S (−25.93, P < 0.01), together with uni-modal mismatch distribution, indicated a recent genetic bottleneck or population expansion of
the species. Analysis of molecular variance (AMOVA) indicated a small amount of differentiation among groups (1.7%); most
of the total variation occurred within groups (98.3%). Also, there was no significant population structure (F
ST = 0.017, P > 0.05), and estimates of gene flows among groups were extremely high (Nm = 28.88), suggesting low genetic divergence between populations in the species. The lack of genetic differentiation among
groups is most likely due to the combined gene flow from the downstream movement of eggs and larvae with currents and the
upstream or downstream migration of adults throughout the distribution. These groups of L. elongata distributed in upper reaches of the Yangtze River should be considered as a single management unit. 相似文献
18.
Dlugokenski RE Sella SR Guizelini BP Vandenberghe LP Woiciechowski AL Soccol CR Minozzo JC 《Applied microbiology and biotechnology》2011,90(2):713-719
A novel low-cost medium was developed from by-products and wastes from the ethanol agro-industry to replace commercial media
in the production of a steam sterilization biological indicator (BI). Various recovery media were developed using soybean
or sugarcane molasses and vinasse to prepare a self-contained BI. Media performance was evaluated by viability and heat resistance
(D
121 °C value) according to regulatory standards. A medium produced with a soybean vinasse ratio of 1:70 (1.4%) (w/v) produced the results, with D
121 °C = 2.9 ± 0.5 min and Usk = 12.7 ± 2.1 min. The addition of 0.8% (w/v) yeast extract improved the germination of heat-damaged spores. The pH variation from 6.0 to 7.3 resulted in a gradual increase
in the D
121 °C value. The absence of calcium chloride resulted in a decrease in germination, while no significant differences were observed
with starch addition. Soybean vinasses may thus be used as the main component of a culture medium to substitute for commercial
media in the production of self-contained biological indicators. The use of ethanol production waste in this biotechnological
process realized a reliable performance, minimized the environmental impact, and decreased BI production costs while producing
a high quality product. 相似文献
19.
Tiecheng Qiao Robert Witkowski Robin Henderson G. McLendon 《Journal of biological inorganic chemistry》1996,1(5):432-438
The kinetics of methemoglobin reduction by cytochrome b
5 has been studied by stopped-flow and saturation transfer NMR. A forward rate constant k
f = 2.44×104 M–1 s–1 and a reverse rate constant k
b = 540 M–1s–1 have been observed at 10 mm, pH 6.20, 25 °C. The ratio k
f/k
b = k
eq = 43.6 is in good agreement with the equilibrium constant calculated from the electrochemical potential between cyt b
5 and methemoglobin. A bimolecular collisional mechanism is proposed for the electron transfer from cyt b
5 to methemoglobin based on the kinetic data analysis. The dependence of the rate constants on ionic strengths supports such
collisional mechanism. It is also found that the reaction rate strongly depends on the conformations of methemoglobin.
Received: 20 February 1996 / Accepted: 4 June 1996 相似文献
20.
J. B. Gaughan T. L. Mader S. M. Holt M. L. Sullivan G. L. Hahn 《International journal of biometeorology》2010,54(6):617-627
Cattle production plays a significant role in terms of world food production. Nearly 82% of the world’s 1.2 billion cattle
can be found in developing countries. An increasing demand for meat in developing countries has seen an increase in intensification
of animal industries, and a move to cross-bred animals. Heat tolerance is considered to be one of the most important adaptive
aspects for cattle, and the lack of thermally-tolerant breeds is a major constraint on cattle production in many countries.
There is a need to not only identify heat tolerant breeds, but also heat tolerant animals within a non-tolerant breed. Identification
of heat tolerant animals is not easy under field conditions. In this study, panting score (0 to 4.5 scale where 0 = no stress
and 4.5 = extreme stress) and the heat load index (HLI) [HLIBG<25°C = 10.66 + 0.28 × rh + 1.30 × BG – WS; and, HLI BG> 25°C = 8.62 + 0.38 × rh + 1.55 × BG – 0.5 × WS + e(2.4 – WS), where BG = black globe temperature (oC), rh = relative humidity (decimal form), WS = wind speed (m/s) and e is the base of the natural logarithm] were used to
assess the heat tolerance of 17 genotypes (12,757 steers) within 13 Australian feedlots over three summers. The cattle were
assessed under natural climatic conditions in which HLI ranged from thermonuetral (HLI < 70) to extreme (HLI > 96; black globe
temperature = 40.2°C, relative humidity = 64%, wind speed = 1.58 m/s). When HLI > 96 a greater number (P < 0.001) of pure bred Bos taurus and crosses of Bos taurus cattle had a panting score ≥ 2 compared to Brahman cattle, and Brahman-cross cattle. The heat tolerance of the assessed breeds
was verified using panting scores and the HLI. Heat tolerance of cattle can be assessed under field conditions by using panting
score and HLI. 相似文献