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1.
P. Gemeiner L'. Kurillová A. Malovíková D. Tóth D. Tomašovičová 《Folia microbiologica》1989,34(3):214-227
Water-soluble acidic polysaccharides—deesterified pectins and carboxy-derivatives of starch—precipitated with calcium ions
were tested as precursors of spherical calcium gels. Pectates prepared from apple or citrus pectin, similarly to alginates,
are compounds forming spherical calcium gels stable in aqueous medium which have a relatively highly reproducible mass, particle
size, water content, shape, mechanical strength and shearing. Both the liquid-solid partition of low- and high-molar-mass
solutes and its kinetics proved to be reasonable features. Distribution of pore size in the above materials was estimated.
Detailed pictures of surface and of the interior of calcium beads in the scanning electron microscope are presented. The possible
use of calcium beads as enzyme carriers, as affinity matrixes and entrapment materials for diffusion chromatography, solids
separations and bioindication of a specific water pollution was evaluated. Calcium alginate beads were always used as reference
material. 相似文献
2.
K. J. Han W. D. Pitman M. W. Alison D. L. Harrell H. P. Viator M. E. McCormick K. A. Gravois M. Kim D. F. Day 《Bioenergy Research》2012,5(3):748-758
Sweet sorghum (Sorghum bicolor (L.) Moench) is currently recognized throughout the world as a highly promising biomass energy crop. Production systems and management practices for sweet sorghum have not been fully developed for the USA, although sporadic research efforts during recent decades have provided some insights into production of sweet sorghum primarily for fermentable sugar production. Field plot experiments were conducted at sites across Louisiana to assess biomass and sugar yield responses to N fertilizer, plant density, and selected cultivars. Although linear increases in stem biomass production and fermentable sugar yield were obtained with increasing N fertilizer rate under irrigated conditions, most of the increase was from the initial 45 kg N ha−1 increment. Nitrogen fertilization increased stem biomass production but not fermentable sugar yield in some non-irrigated environments. Increased plant density contributed to fermentable sugar yield only under growth-limiting conditions, particularly under limited soil moisture. Location effects indicate that sweet sorghum may not be suitable for some sub-optimal cropland and pasture environments in Louisiana. During the primary growing season, cultivar did not affect fermentable sugar yields, although Dale was consistently high in sugar concentration during this period. Nitrogen fertilizer increased fermentable sugar yields only when moisture was not limiting. Overall results indicate that in environments where soil moisture limits plant growth, sugar yield responses are likely from increased plant density and not from increased N fertilization. 相似文献
3.
Sandra Regina B. R. Sella Belquis P. Guizelini Luciana P. S. Vandenberghe Adriane B. P. Medeiros Carlos Ricardo Soccol 《Applied microbiology and biotechnology》2009,82(6):1019-1026
Bacillus atrophaeus’ spores are used in the preparation of bioindicators to monitor the dry heat, ethylene oxide, and plasma sterilization processes
and in tests to assess sterilizing products. Earlier production methods involved culture in chemically defined medium to support
sporulation with the disadvantage of requiring an extended period of time (14 days) besides high cost of substrates. The effect
of cultivation conditions by solid-state fermentation (SSF) was investigated aiming at improving the cost–productivity relation.
Initial SSF parameters such as the type of substrate were tested. Process optimization was carried out using factorial experimental
designs and response surface methodology in which the influence of different variables—particle size, moisture content, incubation
time, pH, inoculum size, calcium sources, and medium composition—was studied. The results have suggested that soybean molasses
and sugarcane bagasse are potential substrate and support, respectively, contributing to a 5-day reduction in incubation time.
Variables which presented significant effects and optimum values were mean particle size (1.0 mm), moisture content (93%),
initial substrate pH (8.0), and water as a solution base. The high-yield spore production was about 3 logs higher than the
control and no significant difference in dry heat resistance was observed. 相似文献
4.
The objective of the present study was to develop membrane-moderated transdermal systems of ampicillin sodium and to evaluate
them with respect to various in vitro and in vivo parameters. The membrane-type transdermal systems were prepared using a
drug with various antinucleant polymers— hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), cellulose acetate phthalate,
chitosan, sodium alginate (SA), and sodium carboxymethylcellulose—in an ethanol: pH 4.7 buffer volatile system by the solvent
evaporation technique with HPMC as the rate-controlling membrane for all the systems. The swelling properties of the polymers
were studied, and drug-polymer interaction studies were performed. The patches were subjected to various physicochemical studies,
in vitro release studies, permeation studies, and skin irritation studies. The best patch among the formulations was selected
for further in vivo studies. Compared to the other patches, SA exhibited the highest moisture content at 16%; a 21% moisture
uptake was found with MC. The release and permeation of the drug from the SA patch was found to be the maximum. The in vivo
study of the SA patch exhibited a peak plasma concentration Cmax of 126 μg/mL at Tmax 4 hours. Hence, it can be concluded that hydrophilic ampicillin sodium can be developed as a transdermal delivery system
with SA that is an alternative to intravenous administration and has minimal adverse effects.
Published: January 26, 2007 相似文献
5.
The general fluid transport equation presented in Part-I of this paper is used for predicting moisture transport and viscoelastic stresses during sorption and drying of soybeans. Predicted drying curves were validated using experimental data obtained from literature (average absolute difference 6-13%). For drying temperatures used in the soybean processing industry (70–93 °C), smooth moisture profiles were obtained, which indicated Fickian (Darcian) transport. As the drying temperature approached the glass transition temperature (25 °C at 10% moisture content), the moisture profiles became sharper, which indicated non-Fickian (non-Darcian) transport. The viscoelastic stress profiles clearly exhibited the role of the force terms during imbibition and drying. Increase in drying temperature tends to decrease the stress relaxation function but reduction in moisture content during drying tends to increase it. The increase in stress due to the reduction in moisture content below 10% was not compensated by an increase in drying temperature. Drying of soybeans below 10% moisture content should be avoided in the industry because this will lead to thicker flakes that reduce the amount of oil recovery. During imbibition of soybeans, a high magnitude of stresses was obtained in the rubbery regions, which may cause critical regions prone to fissuring. The role of glass transition on stress development and critical region development was clearly observed during drying and imbibition of soybeans.Revised version: 5 October 2003 相似文献
6.
Peter Zeilhofer 《Wetlands Ecology and Management》2006,14(5):445-461
Keywords Multitemporal data sets from the Landsat Thematic Mapper (TM) were used to evaluate their applicability for exploratory soil
mapping in the floodplain of the Northern Pantanal of Mato Grosso, Brazil. Fifty-four soil profiles were classified into 21
soil units according to the FAO–UNESCO system. Information layers of vegetation types and dynamics of flooding were elaborated
by applying supervised hierarchical classification rules. Geomorphologic units were mapped by visual image interpretation.
Multinomial logistic regression was applied to test relations between thematic layers and soil units as well as aggregated
soil clusters, developing a statistical mapping model. Northern Pantanal floodplain soils show a high variability as a function
of age and granulemetry of underlying sediments, as well as soil moisture and flooding regimes. GIS layers of nine vegetation
formations, three geomorphologic units and three multi-temporal moisture types were elaborated. Cross-tabulations and multinomial
logistic regression models indicate significant relations between FAO–UNESCO soil units and GIS layers. As soil sampling density
had been low, a final predictive model was developed for the mapping of six aggregated soil clusters, obtaining a high significance
level (p<0.05) for prediction. Applied methodology was found to be appropriate to develop models on soil–landscape relationships and
improve information on spatial distribution of soil groupings in the Northern Pantanal. 相似文献
7.
The effect of the state of aggregation of casein (micellar or non-micellar, as milk protein concentrate [MPC] or sodium caseinate
[Na-caseinate], respectively) on water sorption, plasticization, and crystallization of freeze-dried matrices containing sucrose,
lactose or their blends were studied. The Guggenheim–Anderson–de Boer (GAB) equation satisfactorily fitted to the water sorption
data. In most cases, sugar crystallization—studied by water sorption behavior, x-ray diffraction, and non-isothermal calorimetry—occurred
significantly slower in systems containing Na-caseinate compared to MPC. The type of casein did not affect the temperature
range where the glass transition (T
g) was observed. Sugar/Na-caseinate mixtures showed higher instant crystallization temperatures (up to 20°C) than sugar/MPC
mixtures. X-ray diffraction showed that: (a) crystallinity increased with increasing relative vapor pressure (RVP) > 44%;
(b) lactose crystallized mainly as α-lactose monohydrate regardless of casein type; and (c) that sucrose crystals predominated
the patterns of the sucrose/lactose mixtures. Results suggested that the way proteins organize in space (i.e., aggregation
state) affected their interactions with neighboring sugar and water molecules, which led to differences in sugar crystallization
behavior.
Poster presented at the 4th International Workshop on Water in Food in Brussels March, 2006.
Funded by CONACyT (Mexico) and Dippin’ Dots Inc., KY, USA. 相似文献
8.
We studied how plant species distribution was regulated by the relationships between vegetation and soil factors on the southwestern
coast of South Korea. Vegetation was classified using two-way indicator species analysis (TWINSPAN), thereby producing four
vegetation groups that were linked to three habitat types. Two ordination techniques —; detrended correspondence analysis
(DCA) and canonical correspondence analysis (CCA) —; were applied to examine the relationships between vegetation and 12 edaphic
factors, including soil pH, water and osmotic potentials, moisture content, electrical conductivity, Cl and Na+ contents, total Kjeldahl nitrogen, and contents of organic matter, sand, silt, and clay. Results were similar for both types
of evaluations. According to DCA and CCA, the 23 communities tended to cluster into three types: salt swamp, salt marsh, and
sand dune. The first two canonical axes accounted for 14.9% of the community-soil factor relationship among communities. As
identified via CCA, the main gradients were soil-water relations and soil texture. 相似文献
9.
K. L. Sahrawat 《Plant and Soil》1984,78(3):401-408
Summary Studies of urease activity in an Indian Vertisol and Alfisol using both buffer (THAM pH 9.0) and non-buffer methods for assay
of the urease activity showed that activity increased with increase in temperature from 10°C to a maximum at 60°C (Vertisol)
and 70°C (Alfisol). Further increase in temperature decreased urease activity which was nearly totally inhibited at 100°C.
Urease activity was not detected in soil samples collected in late summer when the soil moisture content was far below — 15
bar pressure. Urease activity increased with increase in moisture content up to field capacity and remained constant with
further increase in moisture content. The relevance of these findings to the ICRISAT improved management practices for Vertisols,
which involve seeding of crops into dry soil just before the onset of rains is discussed.
Approved as Journal Article No. 288 by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). 相似文献
10.
Taraxacum officinala andTaraxacum laevigatum were grown in mixed stands at various plant densities and mixing ratios with various levels of soil moisture to formulate
the effect of soil moisture on the competitive relationship between the species. In pure stands, the mean plant weight—plant
density relation for each level of soil moisture could be described by the reciprocal equation of the crowding effect. On
the other hand, the response of mean plant weight to soil moisture content followed the reciprocal equation for a repulsive
growth factor at the respective levels of plant density. By introducing the density conversion factor, the results of mixed
stands could be successfully formulated from similar reciprocal equations. The dependence of density conversion factor on
soil moisture content was also formulated. From these relations, a comprehensive formula was developed to describe the effects
of plant density and soil moisture content on the growth of two species in mixed stands. Changes in the biomass in mixed stands
were, examined by means of calculations based on the experimental results. 相似文献
11.
The influence of plant transpiration on the entropy exchange was quantified as associated with the degradation of solar energy
on the Earth’s surface covered by plants. Two surfaces were studied: (1) productive surface — plant transpiration taken as
equal to the potential one, (2) non-productive surface — plant transpiration taken as equal to zero. The entropy exchanges
associated with the absorption of solar radiation and with the conversion of absorbed solar radiation into the sensible heat
and latent heat were taken into account. These processes were examined in the experimental watershed Liz (828–1074 m a.s.l.)
located in the Bohemian Forest (Czech Republic). We found that in the growing season 1992 the net entropy exchange in humid
hydrologic period (the Earth’s surface is productive) was considerably higher than in the arid one (the Earth’s surface was
productive in 39% of days, and non-productive in 61% of days). Considering that the biotic effect on the Earth’s functioning
can be measured with the help of the net entropy exchange, we can assume that the theory that biotic activities — represented
by plant transpiration here — are the cause of the self-organizing processes in Earth’s environment is proved in the watershed
scale.
Presented at the International Conference on Bioclimatology and Natural Hazards, Poľana nad Detvou, Slovakia, 17–20 September
2007. 相似文献
12.
Charles L. Bowman 《Cell biochemistry and biophysics》1998,29(3):203-223
I used capillary rise methods to investigate the lumenal surface properties of quartz (fused silica, Amersil T-08), borosilicate
(Corning 7800), and high-lead glass (Corning 0010) capillaries commonly used to make patch pipets. I calculated the capillary
rise and contact angle for water and methanol from weight measurements. The capillary rise was compared with the theoretical
maximum value calculated by assuming each fluid perfectly wetted the lumenal surface of the glass (i.e., zero contact angle,
which reflects the absence of surface contamination). For borosilicate, high-lead, and quartz capillaries, the rise for water
was substantially less than the theoretical maximum rise. Exposure of the borosilicate, lead, and quartz capillaries to several
cleaning methods resulted in substantially better—but not perfect—agreement between the theoretical maximum rise and calculated
capillary rise. By contrast, the capillary rise for methanol was almost identical in untreated and cleaned capillaries, but
less than its theoretical maximum rise. The residual discrepancy between the observed and theoretical rise for water could
not be improved on by trying a variety of cleaning procedures, but some cleaning methods were superior to others. The water
solubility of the surface contaminants, deduced from the effectiveness of repeated rinsing, was different for each of the
three types of capillaries examined: Corning 7800>quartz>Corning 0010. A surface film was also detected in quartz tubing with
an internal filament. I conclude that these borosilicate, quartz, and high-lead glass capillaries have a film on the lumenal
surface, which can be removed using appropriate cleaning methods. The surface contaminants may be unique to each type of capillary
and may also be hydrophobic. Two simple methods are presented to quantitate the cleanliness of glass capillary tubing commonly
used to make pipets for studies of biological membranes. It is not known if the surface film is of importance in electrophysiological
studies of biological membranes. 相似文献
13.
Ronald G. Iacocca Nick Toltl M. Allgeier B. Bustard Xia Dong M. Foubert J. Hofer S. Peoples T. Shelbourn 《AAPS PharmSciTech》2010,11(3):1340-1349
Delamination, or the generation of glass flakes in vials used to contain parenteral drug products, continues to be a persistent
problem in the pharmaceutical industry. To understand all of the factors that might contribute to delamination, a statistical
design of experiments was implemented to describe this loss of chemical integrity for glass vials. Phase I of this study focused
on the effects of thermal exposure (prior to product filling) on the surface chemistry of glass vials. Even though such temperatures
are below the glass transition temperature for the glass, and parenteral compounds are injected directly into the body, data
must be collected to show that the glass was not phase separating. Phase II of these studies examined the combined effects
of thermal exposure, glass chemistry, and exposure to pharmaceutically relevant molecules on glass delamination. A variety
of tools was used to examine the glass and the solution contained in the vial including: scanning electron microscopy and
dynamic secondary ion mass spectroscopy for the glass; and visual examination, pH measurements, laser particle counting, and
inductively coupled plasma–optical emission spectrometry for the analysis of the solution. The combined results of phase I
and II showed depyrogenation does not play a significant role in delamination. Terminal sterilization, glass chemistry, and
solution chemistry are the key factors in the generation of glass flakes. Dissolution of silica may be an effective indicator
that delamination will occur with a given liquid stored in glass. Finally, delamination should not be defined by the appearance
of visible glass particulates. There is a mechanical component in the delamination process whereby the flakes must break away
from the interior vial surface. Delamination should be defined by the observation of flakes on the interior surface of the
vial, which can be detected by several other analytical techniques. 相似文献
14.
The plant communities and their microclimates were surveyed and observed, and the soil fertilities were determined in six
plots of evergreen broadleaved forests of different sizes and similar slope aspects on Jinyun Mountains of Chongqing in China
from April to October, 2003. The relationships of biotic and abiotic factors were analyzed using the Simpson, Shannon—Wiener,
and Hill diversity indices, and stepwise multilinear regression analyses techniques. The results showed that compared with
continuous evergreen broadleaved forests, five fragmentations had a lower species diversity index, and different life forms
showed differences in diversity index. With the decrease in patch areas, the daily differences in air temperature (ΔTa), ground
surface temperature (ΔTs), daily differences in relative humidity (ΔRH), maximum wind velocity (Vmax), differences in photosynthetic
available radiation (ΔPAR) (at noon) of both edges and interiors, all tended to increase. Maximum wind velocity (Vmax) and
photo effective radiation in forest edges were higher than those in interior forest, which presented a stronger temperature-gained
edge effect. In all the fragmentations of evergreen broadleaved forests, the depth of the edge effect was the nearest from
interior forest in the biggest patch (about 15 meters away from interior forest), while the depth of the edge effect was the
farthest from interior forest in the smallest patch (about 25 meters away from interior forest). With regard to the water
conservation function, soil water content improved along with increasing species diversity. Some of the nutritional function
substances of soil increased with increasing species diversity. The elements of microclimate, such as Ta, ΔTa, ΔTs, ΔRH, Vmax,
and PAR, changed along with the extent of fragmented forest.
Translated from Acta Ecologica Sinica, 2005, 25(7): 1642–1648 [译自: 生态学报] 相似文献
15.
The structure of root-associated bacterial populations in the legume common bean (Phaseolus vulgaris L.), was studied in plants grown under nitrogen sufficiency and under conditions inducing nitrogen deficiency. Similar cell
numbers were obtained in the rhizosphere of nitrogen-amended plants as compared to nitrogen-deficient plants and between various
root parts—tip, elongation and branching zones—using DAPI staining. In contrast, a higher proportion of DAPI-stained cells
from the nitrogen-amended plants hybridized with a fluorescence-labeled EUB338 probe for theBacteria domain than cells originating from nitrogen-deficient plants. Shifts in the percentages of EUB338-reactive cells—as well
as in absolute cell number—hybridizing to fluorescent rRNA-directed probes specific for the α and γProteobacteria and for high GC content gram-positive bacteria in separated root segments were detected between the treatments. No such differences
were found using β and δProteobacteria or rRNA group I pseudomonad targeted probes. Denaturating gradient gel electrophoresis profiles of PCR products obtained
from the same samples and amplified withBacteria-domain targeted primers supported the results obtained with the whole cell hybridizations. The advantages and drawbacks of
the techniques applied are discussed. 相似文献
16.
N. V. Chernova 《Journal of Ichthyology》2011,51(10):825-924
Chorological structure of ichthyofauna of the Arctic Region is described. Distribution patterns of 504 fish-like vertebrates
and fish species are characterized. One hundred and eighty-nine range types are defined, which are combined into eight main
categories: 1—Arctic; 2—Atlantic-Arctic; 3—transitional subarctic zone of Atlantic sector; 4—Pacific-Arctic; 5—transitional
subarctic subarctic zone of Pacific sector, 6—Pacific-Atlantic (amphiboreal); 7—bipolar; 8—continental (fresh and brackish
waters). Arctic and boreal regions are bordered by transitional (subarctic) zones, which are the areas of intermutual penetration
of faunas. The distribution of most fish species that penetrate into to the Arctic Region from the southern areas is limited
by these transitional zones. The benthic fish species prevail in the group of autochthonous Arctic species (which includes
64 species or 14% of marine fauna). The demersal fauna of the Arctic preudoabyssal is presented by endemic species. Ten variations
of amphiboreal distribution patterns are revealed. Three areas may be defined within the Atlantic-subarctic zone in regard
to the fish fauna and range types, i.e., Labrador-Greenland region, the Barents Sea region, and Icelandic (transitional) region. 相似文献
17.
DO-YUN YU WOOKEUN BAE NAMGOO KANG M. KATHERINE BANKS CHUL-HO CHOI 《Soil & Sediment Contamination》2005,14(3):231-247
Laboratory scale batch experiments were performed to investigate the decomposition characteristics of gaseous ozone in porous media. The decomposition rates of gaseous ozone in several solid media were determined, and the relationship of moisture content with sorbed ozone molecules was evaluated. Ozone decomposition in control and glass beads packed columns followed second-order reaction kinetics, while ozone consumption in a sand-packed column demonstrated first-order kinetics with a rate constant of 0.0109 min?1 and half-life of 1.0 h. The presence of typical metal oxides in the soil resulted in ozone consumption rates in the following order: hematite (Fe2O3) > silica-alumina (SiO2Al2O3) > alumina (Al2O3) > silica (SiO2). Ozone decomposition was highly dependent upon soil moisture content. Over 90% of the total ozone mass decomposed in the field soil with moisture content at less than 1 wt%, whereas as low as 5–15% of the total ozone mass degraded with moisture content at more than 2 wt%. In conclusion, ozone decomposition in soils was primarily controlled not only by soil organic matter but also by reactive metal oxides on the soil surface. These two factors were shown to be highly dependent upon soil moisture content. 相似文献
18.
Staining cuticular membranes ofAgave americana andClivia miniata en bloc with potassium permanganate results in a strong contrast in the interior cuticular layer while the exterior part remains unstained. This is not caused by a selective chemical reaction with the interior part but by the unidirectional penetration of the reagent from the interior side, the outside being protected by the cuticle proper. In transverse cryosections of the cuticular membrane, permanganate penetrates nearly as easily into the exterior cuticular layer as into the interior one giving the same contrast. However, compared with the periclinal penetration into the cuticle proper this penetration is accelerated five-to tenfold by the polysaccharide network within the cuticular layer which serves as a distribution-channel system. Periclinal penetration into the cuticle proper occurs independently in each cutin penetration unit included between two obvious lucent lamellae and further divided into subunits. 相似文献
19.
Dhaval P. Patel Chitral Mallikarjuna Setty Gaurav N. Mistry Santnu L. Patel Tarun J. Patel Pritesh C. Mistry Amar K. Rana Pritesh K. Patel Rishabh S. Mishra 《AAPS PharmSciTech》2009,10(2):437-442
Transdermal films of the furosemide were developed employing ethyl cellulose and hydroxypropyl methylcellulose as film formers.
The effect of binary mixture of polymers and penetration enhancers on physicochemical parameters including thickness, moisture
content, moisture uptake, drug content, drug–polymer interaction, and in vitro permeation was evaluated. In vitro permeation study was conducted using human cadaver skin as penetration barrier in modified Keshary–Chein diffusion cell.
In vitro skin permeation study showed that binary mixture, ethyl cellulose (EC)/hydroxypropyl methylcellulose (HPMC), at 8.5:1.5 ratio
provided highest flux and also penetration enhancers further enhanced the permeation of drug, while propylene glycol showing
higher enhancing effect compared to dimethyl sulfoxide and isopropyl myristate. Different kinetic models, used to interpret
the release kinetics and mechanism, indicated that release from all formulations followed apparent zero-order kinetics and
non-Fickian diffusion transport except formulation without HPMC which followed Fickian diffusion transport. Stability studies
conducted as per International Conference on Harmonization guidelines did not show any degradation of drug. Based on the above
observations, it can be reasonably concluded that blend of EC–HPMC polymers and propylene glycol are better suited for the
development of transdermal delivery system of furosemide. 相似文献
20.
Low-moisture biopolymer-based systems are commonly encountered in food. Obviously, understanding the physical basis of their
quality [texture, or performance over time or as a function of their composition (water or other added solutes)] is of primary
importance. A polymer science approach using physical chemistry concepts based on physical state, phase transitions and molecular
mobility can be applied to investigate the performances of food in particular versus moisture. Based on the example of starch-based
samples and their texture property changes versus composition, the role of water and sucrose is considered through different
aspects. The relations existing between the observed changes and physical state are investigated. While the motions associated
with the glass transition were observed at high temperature, secondary relaxations are observed below Tg (at T
β): T
β decreased with water content and increased with increasing sucrose content. These local motions are suggested to contribute
to the observed texture modifications versus water. Moreover, the stability of the glassy state was investigated by differential
scanning calorimetry through the study of enthalpy relaxation (physical ageing). The amplitude of enthalpy relaxation decreased
with both increasing sucrose and water content. All in all, this study strengthened the hypotheses that sub-Tg mobility could
contribute to texture instability versus moisture or sugar content. 相似文献