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1.
Sarah A. Cocherell Gardner J. Jones Javier B. Miranda Dennis E. Cocherell Joseph J. CechJr. Lisa C. Thompson A. Peter Klimley 《Environmental Biology of Fishes》2010,89(2):105-116
We tracked the movements of ten small (SL = 25.5–31.0 cm) and ten large (SL = 32.0–38.5 cm) radio-tagged domestic rainbow
trout (Oncorhynchus mykiss) in response to frequent pulsed releases of water in the South Fork American River (California) from July to October 2005.
In week one all the small trout moved less than 1 km upstream or downstream of their release sites. Four small trout moved
1–3 km upstream or downstream of their release sites in the following 8 weeks. Seven out of ten large trout moved downstream
after their release. In subsequent weeks most large trout showed smaller upstream and downstream movements, and were observed
between 1 km upstream and 8 km downstream of their release sites. Our results suggest that domestic rainbow trout with SL > 25 cm
are not forced downstream by daily pulsed flow increases from 5 to over 40 m3s−1. 相似文献
2.
Siahi-Shadbad MR Asare-Addo K Azizian K Hassanzadeh D Nokhodchi A 《AAPS PharmSciTech》2011,12(4):1176-1182
The objective of this study was to investigate the release behaviour of propranolol hydrochloride from psyllium matrices in
the presence hydrophilic polymers. The dissolution test was carried out at pH 1.2 and pH 6.8. Binary mixtures of psyllium
and hydroxypropyl methylcellulose (HPMC) used showed that an increase in the percentage of HPMC in the binary mixtures caused
a significant decrease in the release rate of propranolol. Psyllium–alginate matrices produced lower drug release as compared
to when the alginate was the matrix former alone. When sodium carboxy methyl cellulose (NaCMC) was incorporated into the psyllium,
the results showed that matrices containing the ratio of psyllium–NaCMC in the 1:1 ratio are able to slow down the drug release
significantly as compared to matrices made from only psyllium or NaCMC as retardant agent suggesting that there could be a
synergistic effect between psyllium and NaCMC. The double-layered tablets showed that the psyllium and HPMC in the outer shell
of an inner formulation of psyllium alone had the greatest effect of protecting the inner core and thus producing the lowest
drug release (DE = 38%, MDT = 93 min). A significant decrease in the value of n in Q = kt
n
from 0.70 to 0.51 as the psyllium content was increased from 50 to 150 mg suggests that the presence of psyllium in HPMC
matrices affected the release mechanism. Psyllium powder had the ability in the combination with other hydrophilic polymers
to produce controlled release profiles. Care and consideration should as such be taken when formulating hydrophilic matrices
in different combinations. 相似文献
3.
People adapt to thermal environments, such as the changing seasons, predominantly by controlling the amount of clothing insulation, usually in the form of the clothing that they wear. The aim of this study was to determine the actual daily clothing insulation on sedentary human subjects across the seasons. Thirteen females and seven males participated in experiments from January to December in a thermal chamber. Adjacent months were grouped in pairs to give six environmental conditions: (1) January/February = 5°C; (2) March/April = 14°C; (3) May/June = 25°C; (4) July/August = 29°C; (5) September/October = 23°C; (6) November/December = 8°C. Humidity(45 ± 5%) and air velocity(0.14 ± 0.01 m/s) were constant across all six experimental conditions. Participants put on their own clothing that allowed them to achieve thermal comfort for each air temperature, and sat for 60 min (1Met). The clothing insulation (clo) required by these participants had a significant relationship with air temperature: insulation was reduced as air temperature increased. The range of clothing insulation for each condition was 1.87–3.14 clo at 5°C(Jan/Feb), 1.62–2.63 clo at 14°C(Mar/Apr), 0.87–1.59 clo at 25°C(May/Jun), 0.4–1.01 clo at 29°C(Jul/Aug), 0.92–1.81 clo at 23°C (Sept/Oct), and 2.12–3.09 clo at 8°C(Nov/Dec) for females, and 1.84–2.90 clo at 5°C, 1.52–1.98 clo at 14°C, 1.04–1.23 clo at 25°C, 0.51–1.30 clo at 29°C, 0.82–1.45 clo at 23°C and 1.96–3.53 clo at 8°C for males. The hypothesis was that thermal insulation of free living clothing worn by sedentary Korean people would vary across seasons. For Korean people, a comfortable air temperature with clothing insulation of 1 clo was approximately 27°C. This is greater than the typical comfort temperature for 1 clo. It was also found that women clearly increased their clothing insulation level of their clothing as winter approached but did not decrease it by the same amount when spring came. 相似文献
4.
Nicola D’Amelio Luca Fontanive Fulvio Uggeri Furio Suggi-Liverani Luciano Navarini 《Food biophysics》2009,4(4):321-330
Caffeine complexation by chlorogenic acid (3-caffeoylquinic acid, CAS Number [327-97-9]) in aqueous solution as well as caffeine–chlorogenate
complex in freshly prepared coffee brews have been investigated by high-resolution 1H-NMR. Caffeine and chlorogenic acid self-associations have also been studied and self-association constants have been determined
resorting to both classical isodesmic model and a recently introduced method of data analysis able to provide also the critical
aggregation concentration (cac). Furthermore, caffeine–chlorogenate association constant was measured. For the caffeine, the
average value of the self-association constant determined by isodesmic model (K
i = 7.6 ± 0.5 M−1) is in good agreement with the average value (K
a = 10 ± 1.8 M−1) determined with the method which permits the determination of the cac (8.43 ± 0.05 mM). Chlorogenic acid shows a slight
decreased tendency to aggregation with a lower average value of association constants (K
i = 2.8 ± 0.6 M−1; K
a = 3.4 ± 0.6 M−1) and a critical concentration equal to 24 ± 1 mM. The value of the association constant of the caffeine–chlorogenate complex
(30 ± 4 M−1) is compatible with previous studies and within the typical range of reported association constants for other caffeine–polyphenol
complexes. Structural features of the complex have also been investigated, and the complex conformation has been rediscussed.
Caffeine chemical shifts comparison (monomeric, complexed, coffee brews) clearly indicates a significant amount of caffeine
is complexed in beverage real system, being chlorogenate ions the main complexing agents. 相似文献
5.
Solovchenko A Khozin-Goldberg I Recht L Boussiba S 《Marine biotechnology (New York, N.Y.)》2011,13(3):527-535
In order to develop a practical approach for fast and non-destructive assay of total fatty acid (TFA) and pigments in the
biomass of the marine microalga Nannochloropsis sp. changes in TFA, chlorophyll, and carotenoid contents were monitored in parallel with the cell suspension absorbance.
The experiments were conducted with the cultures grown under normal (complete nutrient f/2 medium at 75 μmol PAR photons/(m2 s)) or stressful (nitrogen-lacking media at 350 μmol PAR photons/(m2 s)) conditions. The reliable measurement of the cell suspension absorbance using a spectrophotometer without integrating
sphere was achieved by deposition of cells on glass–fiber filters in the chlorophyll content range of 3–13 mg/L. Under stressful
conditions, a 30–50% decline in biomass and chlorophyll, retention of carotenoids and a build-up of TFA (15–45 % of dry weight)
were recorded. Spectral regions sensitive to widely ranging changes in carotenoid-to-chlorophyll ratio and correlated changes
of TFA content were revealed. Employing the tight inter-correlation of stress-induced changes in lipid metabolism and rearrangement
of the pigment apparatus, the spectral indices were constructed for non-destructive assessment of carotenoid-to-chlorophyll
ratio (range 0.3–0.6; root mean square error (RMSE) = 0.03; r
2 = 0.93) as well as TFA content of Nannochloropsis sp. biomass (range 5.0–45%; RMSE = 3.23 %; r
2 = 0.89) in the broad band 400–550 nm normalized to that in chlorophyll absorption band (centered at 678 nm). The findings
are discussed in the context of real-time monitoring of the TFA accumulation by Nannochloropsis cultures under stressful conditions. 相似文献
6.
Data on zinc concentration in the human body may be used to interpret the results obtained in cases of chronic and acute poisonings
with zinc compounds, i.e., in clinical and forensic toxicology. In this paper, the concentrations of zinc in human tissues
and body fluids obtained from autopsy cases concerning non-poisoned people (n = 203), aged from 14 to 80 years, between 1995 and 2008, are presented. The following values were found by the flame atomic
absorption method (mean ± SD, median, range, in microgram per gram or microgram per milliliter): brain 10.3 ± 1.36, 10.2,
7.99–13.8 (n = 48); stomach 14.2 ± 3.63, 13.6, 8.00–22.5 (n = 71); intestines 15.7 ± 5.22, 15.8, 8.36–28.1 (n = 35); liver 39.6 ± 16.1, 36.6, 16.0–78.8 (n = 109); kidney 33.8 ± 10.1, 31.8, 16.4–60.9 (n = 93); lung 12.0 ± 3.88, 11.0, 6.13–18.7 (n = 26); spleen 14.7 ± 2.53, 14.6, 11.4–18.3 (n = 5); heart 26.5 ± 3.63, 26.7, 22.5–31.8 (n = 5); blood 6.81 ± 1.21, 7.00, 4.02–8.68 (n = 50); urine 0.69 ± 1.70, 0.60, 0.39–1.00 (n = 5), and bile 4.92 ± 1.64, 3.75, 3.20–7.09 (n = 9). The accuracy of the method was checked through the use of SRM Bovine Liver 1577b (certified: 127 ± 16 μg Zn/g, found:
117 ± 0.7 μg Zn/g (n = 6)). 相似文献
7.
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
8.
Riddhika Kalle Tharmalingam Ramesh Qamar Qureshi Kalyanasundaram Sankar 《Acta theriologica》2011,56(4):335-342
Density of tiger Panthera tigris and leopard Panthera pardus was estimated using photographic capture–recapture sampling in a tropical deciduous forest of Mudumalai Tiger Reserve, southern
India, from November 2008 to February 2009. A total of 2,000 camera trap nights for 100 days yielded 19 tigers and 29 leopards
within an intensive sampling area of 107 km2. Population size of tiger from closed population estimator model Mb Zippin was 19 tigers (SE = ±0.9) and for leopards Mh Jackknife estimated 53 (SE = ±11) individuals. Spatially explicit maximum likelihood and Bayesian model estimates were 8.31
(SE = ±2.73) and 8.9 (SE = ±2.56) per 100 km2 for tigers and 13.17 (SE = ±3.15) and 13.01 (SE = ±2.31) per 100 km2 for leopards, respectively. Tiger density for MMDM models ranged from 6.07 (SE = ±1.74) to 9.72 (SE = ±2.94) per 100 km2 and leopard density ranged from 13.41 (SE = ±2.67) to 28.91 (SE = ±7.22) per 100 km2. Spatially explicit models were more appropriate as they handle information at capture locations in a more specific manner
than some generalizations assumed in the classical approach. Results revealed high density of tiger and leopard in Mudumalai
which is unusual for other high density tiger areas. The tiger population in Mudumalai is a part of the largest population
at present in India and a source for the surrounding Reserved Forest. 相似文献
9.
Zhiyong Sun Juliana A. Ramsay Martin Guay Bruce A. Ramsay 《Applied microbiology and biotechnology》2009,82(4):657-662
Unsaturated medium-chain-length polyhydroxyalkanoates (MCL-PHA) were produced at a productivity of 0.63–1.09 g PHA l−1 h−1 with final PHA content ranging from 42.6 to 55.8% in single-stage, carbon-limited, fed-batch fermentations of Pseudomonas putida KT2440. A mixture of nonanoic acid (NA) and 10-undecenoic acid (UDA=) was fed exponentially to control growth rate. Varying the specific growth rate (0.14 h−1 vs. 0.23 h−1) at similar substrate feed ratios (NA:UDA= = 5:1) had little effect on the final PHA content and relative composition. However, decreasing the NA:UDA= ratio decreased the final amount of PHA produced from 56% with NA:UDA= = 5.07:1 to only 42% at NA:UDA= = 2.47:1. The molar fraction of all 3-hydroxyalkanoate monomers in the PHA product was relatively constant throughout each
fermentation, indicating that the final product was homogeneous rather than a mixture of different copolymers. A linear relationship
between unsaturation of the PHA produced and unsaturation of the carbon feed was found, which demonstrates the feasibility
of producing unsaturated MCL-PHAs with controlled polymeric composition in a fed-batch process. 相似文献
10.
The periodicity of otolith growth increments (opaque and translucent zones) from adult red snapper (Lutjanus campechanus) was examined through a mark and recapture study (2005–2010), and laboratory holding of hatchery reared red snapper over
a 2 year period (2002–2004). Wild red snapper (n = 295) were caught hook-and-line, marked with anchor tags, injected with oxytetracycline dihydrate (OTC), and released in
the Gulf of Mexico 15–40 km south of Dauphin Island, Alabama. Marked fish were recaptured up to 2.8 years after release (n = 35) and sagittal otoliths were dissected, sectioned and examined under white and blue-violet light. The number of opaque
growth zones past the OTC mark was compared to time at liberty for each fish and supported an annual periodicity of growth
increment formation. Also, most (87%) of the hatchery reared fish showed two opaque zones that supported an annual increment
formation rate. However, an unusual timing of opaque zone formation was shown for mark-recaptured fish. Based on known timing
of OTC marking, otoliths from mark-recapture fish showed opaque zone formation from late summer (August) to early winter (December).
This fall formation of opaque zones is in contrast to previous studies and its timing may relate to the end of spawning for
this species. 相似文献
11.
Carruyo I Fernández Y Marcano L Montiel X Torrealba Z 《Biological trace element research》2008,125(3):276-285
The present study determines lead content in onion root tip cells (Allium cepa L.), correlating it with its toxicity. The treatment was carried at 25 ± 0.5°C using aqueous solutions of lead chloride at
0.1, 0.25, 0.50, 0.75, and 1 ppm for 12, 24, 48, and 72 h. For each treatment, a control where the lead solution was substituted
by distilled water was included. After treatment, the meristems were fixed with a mixture of alcohol–acetic acid (3:1) and
colored according to the technique of Feulgen. Lead content was quantified by graphite furnace absorption atomic spectrometry.
The lead content in the roots ranged from 3.25 to 244.72 μg/g dry weight, with a direct relation with the concentration and
time of exposure. A significant negative correlation was presented (r = −0.3629; p < 0.01) among lead content and root growth increment, and a positive correlation (r = 0.7750; p < 0.01) with the induction of chromosomic aberrations. In conclusion, lead is able to induce a toxic effect in the exposed
roots, correlated with its content. 相似文献
12.
The main aim of the present study was to evaluate potential of ternary complexation (comprising of drug, cyclodextrin and
polymer) as an approach for taste masking. For this purpose famotidine with property of bitter taste was selected as a model
drug. Improvement in taste masking capability of cyclodextrin towards famotidine was evaluated by formulating a ternary complex
including hydrophilic polymer hydroxyl propyl methyl cellulose (HPMC 5 cps) as the third component. Phase solubility analysis
at 25 °C was carried out for both the binary systems (viz. drug–cyclodextrin and drug–polymer) and the ternary system (drug–cyclodextrin–polymer).
Ternary complex was prepared using solution method and was further characterized using XRD, DSC, FT-IR and microscopic studies.
In vitro dissolution study was carried out to see the effect of ternary complexation on drug release. Taste perception study was carried
out on human volunteers to evaluate the taste masking ability of ternary complexation. Results obtained from phase solubility
analysis showed that the combined use of polymer and cyclodextrin effectively increased the stability constant of the complex
[from 538 M−1 for binary system to 15,096 M−1 for ternary system]. Ternary system showed effective taste masking as compared to binary complex and at the same time showed
no limiting effect on the drug release (D.E15min = 90%). The effective taste masking was attributed to the enhanced complexation of famotidine in ternary system compared
to binary system and the same was confirmed from the characterization studies. In conclusion, the study confirmed that ternary
complexation can be utilized as an alternative approach for effective taste masking. 相似文献
13.
The purpose of this work was to develop and optimize gliclazide-loaded alginate–methyl cellulose mucoadhesive microcapsules
by ionotropic gelation using central composite design. The effect of formulation parameters like polymer blend ratio and cross-linker
(CaCl2) concentration on properties of gliclazide-loaded alginate–methyl cellulose microcapsules like drug encapsulation efficiency
and drug release were optimized. The optimized microcapsules were subjected to swelling, mucoadhesive, and in vivo studies. The observed responses coincided well with the predicted values from the optimization technique. The optimized microcapsules
showed high drug encapsulation efficiency (83.57 ± 2.59% to 85.52 ± 3.07%) with low T
50% (time for 50% drug release, 5.68 ± 0.09 to 5.83 ± 0.11 h). The in vitro drug release pattern from optimized microcapsules was found to be controlled-release pattern (zero order) with case II transport
release mechanism. Particle sizes of these optimized microcapsules were 0.767 ± 0.085 to 0.937 ± 0.086 mm. These microcapsules
also exhibited good mucoadhesive properties. The in vivo studies on alloxan-induced diabetic rats indicated the significant hypoglycemic effect that was observed 12 h after oral
administration of optimized mucoadhesive microcapsules. The developed and optimized alginate–methyl cellulose microcapsules
are suitable for prolonged systemic absorption of gliclazide to maintain lower blood glucose level and improved patient compliance. 相似文献
14.
The purpose of this study was to develop and validate a rapid, sensitive, and specific reversed-phase high-performance liquid
chromatography method for the quantitative determination of native tenofovir (TNF) for various applications. Different analytical
performance parameters such as linearity, precision, accuracy, limit of quantification (LOQ), limit of detection (LOD), and
robustness were determined according to International Conference on Harmonization (ICH) guidelines. A Bridge™ C18 column (150 × 4.6 mm,
5 μm) was used as stationary phase. The retention time of TNF was 1.54 ± 0.03 min (n = 6). The assay was linear over the concentration range of 0.1–10 μg/mL. The proposed method was sensitive with LOD and LOQ
values equal to 50 and 100 ng/mL, respectively. The method was accurate with percent mean recovery from 95.41% to 102.90%
and precise as percent RSD (relative standard deviation) values for intra-day, and inter-day precision were less than 2%.
This method was utilized for the estimation of molar absorptivity of TNF at 259 nm (ε
259 = 12,518 L/mol/cm), calculated from linear regression analysis. The method was applied for determination of percentage of
encapsulation efficiency ( 22.93 ± 0.04%), drug loading (12.25 ± 1.03%), in vitro drug release profile in the presence of enzyme (43% release in the first 3 h) and purification analysis of hyaluronic acid-based
nanomedicine. 相似文献
15.
In this study, the characteristics of extracellular polymeric substance (EPS) fractions of biofilm during the process of establishing
a partial nitrification under salt stress were analyzed in terms of concentrations, molecular weight distribution, and three-dimensional
excitation–emission matrix (EEM) fluorescence spectroscopy. A partial nitrification was formed successfully with a salinity
of 1%. Results indicated that the amount of total EPS increased from 54.2 mg g−1 VSS−1 on day 1 to 99.6 mg g−1 VSS−1 on day 55 due to the NaCl concentration changed from 0 to 10.0 g L−1 in a biofilm reactor. The changes of loosely bound EPS (LB-EPS) compounds under different salt concentrations appeared to
be more significant than those of the tightly bound EPS. A clear release of polysaccharides in the LB-EPS fraction was detected
during the enhancement of salinity. This was considered as a protective response of bacteria to the salinity. Three fluorescence
peaks were identified in the EEM fluorescence spectra of the EPS fraction samples. Two peaks were assigned to the protein-like
fluorophores, and the third peak was located at the excitation/emission wavelengths of 275 nm/425–435 nm of the spectra of
EPS fractions till the salinity maintained constant at 1%. This information is valuable for understanding the characteristics
of EPS isolated from biomass in a saline nitrogen removal system. 相似文献
16.
Muhammad Harris Shoaib Saniah Al Sabah Siddiqi Rabia Ismail Yousuf Kamran Zaheer Muhammad Hanif Saeed Rehana Sabahat Jabeen 《AAPS PharmSciTech》2010,11(2):708-718
The objective of the present study was to develop a once-daily sustained-release (SR) matrix tablet of famotidine. Nine different
formulations (F1–F9) were prepared by direct compression method using Avicel PH101 as filler/binder in the range of 41–27%
in F1–F3, 18–22% in F4–F7, and 16–18% in F8–F9 and hydroxypropyl methylcellulose (4,000 cps) as hydrophilic matrix was used
in F1–F3 from 19% to 30%, around 40% in F4–F7, and 42–45% in F8–F9. Talc and Aerosil were added in the ratio of 0.7–1.2%.
The tablets were subjected to various physical parameters including weight variation test, hardness, thickness, diameter,
friability, and in vitro release studies. Assay was also performed according to the USP 30 NF 25 procedure. The results of the physical parameters
and assay were found to be within the acceptable range. In vitro dissolution results indicated that formulation F4–F7, having around 40% of rate control polymer, produced a SR pattern throughout
24 h. F1–F3 showed drug release at a faster rate, while F8–F9 released much slower, i.e., <80% in 24 h. Model-dependent and
model-independent methods were used for data analysis and the best results were observed for F4 in zero order (r
2 = 0.984) and F6 in Korsmeyer and Higuchi (r
2 = 0.992 and 0.988). The parameter n indicated anomalous diffusion, while β in Weibull showed a parabolic curve with higher initial slope. The f
2 similarity test was performed taking F4 as a reference formulation. Only the F5–F7 formulations were similar to the reference
formulation F4. The mean dissolution time was around 10 h for the successful formulation. 相似文献
17.
Kristina Liesener Valeriu Curtui Richard Dietrich Erwin Märtlbauer Ewald Usleber 《Mycotoxin Research》2010,26(1):23-30
A total of 62 samples of commercial horse feed preparations (complementary feeds) containing cereal mixtures (“muesli” or
mash, n = 39; pelleted feeds, n = 12), and plain horse feed grains (maize, n = 5; oats, n = 4; barley, n = 2) were purchased from 21 different producers/distributors from the German market. All samples were analysed by competitive
enzyme immunoassays (EIA) for six different mycotoxins (mycotoxin groups). Analytes (detection limit, mean recovery) were:
deoxynivalenol (DON, 10 μg/kg, 84%), zearalenone (ZEA, 5 μg/kg, 93%), fumonisin B1 (FB1, 2 μg/kg, 113%), T-2 toxin (T-2, 0.1 μg/kg, 71%), sum of T-2 + HT-2 toxin (T-2/HT2, 0.2 μg/kg, 97%), ochratoxin A (OTA, 0.2 μg/kg,
67%), and total ergot alkaloids (Generic Ergot Alkaloids “GEA”, 30 μg/kg, 132%). All samples contained DON (16–4,900 μg/kg,
median 220 μg/kg), T-2/HT-2 (0.8–230 μg/kg, median 24 μg/kg), and T-2 (0.3–91 μg/kg, median 7 μg/kg). ZEA was detected in
98% of the samples (7–310 μg/kg, median 61 μg/kg). Most samples (94%) were positive for FB1 (2–2,200 μg/kg, median 27 μg/kg). Ergot alkaloids were detected in 61% of samples (28–1,200 μg/kg, median 97 μg/kg), OTA
was found in 42% of samples (0.2–4 μg/kg, median 0.35 μg/kg). The results demonstrate that a co-contamination with several
mycotoxins is very common in commercial horse feed from the German market. The toxin concentrations were in most cases well
below the levels which are usually considered as critical or even toxic. The highest mycotoxin concentrations were mostly
found in single-grain cereal feed: the maximum values for DON and FB1 were found in maize, the highest T-2/HT-2 toxin concentrations were found in oats, and the highest concentration of ergot
alkaloids was found in barley. In composed feeds, no correlation between cereal composition and mycotoxin levels could be
found. 相似文献
18.
Ribitsch D Karl W Wehrschütz-Sigl E Tutz S Remler P Weber HJ Gruber K Stehr R Bessler C Hoven N Sauter K Maurer KH Schwab H 《Applied microbiology and biotechnology》2009,81(5):875-886
In the course of a microbial screening of soil samples for new oxidases, different enrichment strategies were carried out.
With choline as the only carbon source, a microorganism was isolated and identified as Arthrobacter nicotianae. From this strain, a gene coding for a choline oxidase was isolated from chromosomal DNA. This gene named codA was cloned in Escherichia coli BL21-Gold and the protein (An_CodA) heterologously overexpressed as a soluble intracellular protein of 59.1 kDa. Basic biochemical characterization of
purified protein revealed a pH optimum of 7.4 and activity over a broad temperature range (15–70 °C). Specific activities
were determined toward choline chloride (4.70 ± 0.12 U/mg) and the synthetic analogs bis(2-hydroxyethyl)-dimethylammonium
chloride (0.05 ± 0.45 × 10–2 U/mg) and tris-(2-hydroxyethyl)-methylammonium methylsulfate (0.01 ± 0.12 × 10–2 U/mg). With increasing number of oxidizable groups, a significant decrease in activity was noted. Determination of kinetic
parameters in atmorspheric oxygen resulted in K
M = 1.51 ± 0.09 mM and V
max = 42.73 ± 0.42 mU/min for choline chloride and K
M = 4.77 ± 0.76 mM and V
max = 48.40 ± 2.88 mU/min for the reaction intermediate betaine aldehyde respectively. Nuclear magnetic resonance spectroscopic
analysis of the products formed during the enzyme reaction with choline chloride showed that in vitro the intermediate betaine
aldehyde exists also free in solution. 相似文献
19.
A new cultivation technique for Kappaphycus alvarezii was used in the Brazilian southeastern coast (23°02′25″ S and 43°53′39″ W), the tubular netting on floating rafts. The tubular
net technique (TN) was compared with the current method of tie–tie (TT). After 47 days, the daily growth rate (mean ± SD of TN and TT = 3.4 ± 0.7% day−1), carrageenan yield (mean ± SD of TN and TT = 36 ± 1.3%), gel strength (mean ± SD of TN and TT = 730 ± 114.5 g cm2), and
viscosity (mean ± SD of TN and TT = 350 ± 60.4 cP) did not differ between the two techniques (p > 0.05). The amount of time used to plant (TT = 30.2 ± 2.3 min and TN = 13.3 ± 3.4 min) and to harvest the seedlings (TT = 36.2 ± 2.7 min
and TN = 17.8 ± 3.7 min) were lower in TN (p < 0.001). It is concluded that TN was more effective than TT, the cultivation management (time rates used to plant and harvest
the seedlings) was 53.6% faster, no seedlings were lost, the cost was lower, and an estimated return in 1 year of nearly 20%
more than that of the TT technique. 相似文献
20.
Dave Parrott Anthony Prickett Stéphane Pietravalle Thomas R. Etherington Mark Fletcher 《European Journal of Wildlife Research》2012,58(1):23-33
Walked spotlight transect surveys with distance sampling were used to estimate regional population densities of badger (Meles meles), fox (Vulpes vulpes) and brown hare (Lepus europaeus) in south-west England (Cornwall, Devon, Gloucestershire, Herefordshire) and Wales (Pembrokeshire, Borders, North Wales).
All regions were surveyed during spring 2006 with English regions re-surveyed in autumn 2006. In each region, surveys were
conducted in a random sample of 19.6 km2 areas (mean areas per region: spring = 19, autumn = 25). Within each survey area, a semi-random transect was established
in each of a random sample of fields (open habitat almost exclusively pasture). Transects were subsequently walked at night
with spotlights (mean transects per survey area: spring = 21, autumn = 21). Each area was surveyed twice during a season.
Total transect length per region ranged from 137 to 193 km in spring and 230 to 250 km in autumn. The mean density of species
per region was: badger 1.5–4.8 km−2, fox 1.0–4.0 km−2, hare 0.4–4.6 km−2. The study has provided baseline estimates of regional densities against which any future equivalent surveys can be compared.
It has also illustrated the practical application of large-scale walked distance sampling to surveys of British mammals. 相似文献