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排序方式: 共有53条查询结果,搜索用时 31 毫秒
31.
The biogeochemistry of basic cations in two forest catchments with contrasting lithology in the Czech Republic 总被引:2,自引:0,他引:2
PAVEL KRÁM JAKUB HRUŠKA BRIAN S. WENNER CHARLES T. DISCOLL CHRIS E. JOHNSON 《Biogeochemistry》1997,37(2):173-202
The biogeochemistry of Ca, Mg, K, and Nawere investigated in two forested catchments in theCzech Republic, one underlain by leucogranite, theother by serpentinite. High weathering rates at theserpentinite site at Pluhv Bor resultedin Mg2+ as the dominant cation on the soilexchange complex and in drainage water. Other basiccations (Ca2+, K+, Na+) showedrelatively low concentrations and outflow instreamwater. The catchment exhibited high basesaturation in mineral soils (>70%), and nearneutral soil and stream pH, despite elevated inputsof acidic deposition. Slow growth of Norway spruceat Pluhv Bor may be caused by K deficiency, Mgoversupply and/or Ni toxicity. In contrast, thegranitic site at Lysina showed low concentrations ofbasic cations on the soil exchange complex and instreamwater. Soil and drainage water at Lysina werehighly impacted by acidic deposition. Soil pH wasextremely acidic (<4.5) throughout the soilprofile, and the base saturation of the mineral soilwas very low (<5%). Supplies of basic cationsfrom atmospheric deposition and soil processes wereless than inputs of SO2-
4 on anequivalence basis, resulting in low pH and highconcentrations of total Al in drainage water. Needle yellowing in Norway spruce was possibly theresult of Mg deficiency at Lysina. Because of theirextremely different lithologies, these catchmentsserve as valuable end-members of ecosystemsensitivity to elevated levels of acidicdeposition. 相似文献
32.
Vikalp Raj Kaustubh G. Naik Bairav S. Vishnugopi Ajeet Kumar Rana Andrew Scott Manning Smruti Rekha Mahapatra KR Varun Vipin Singh Abhineet Nigam Josefine D. McBrayer Partha P. Mukherjee Naga Phani B. Aetukuri David Mitlin 《Liver Transplantation》2024,14(15):2303062
This study illustrates how the microstructure of garnet solid-state electrolytes (SSE) affects the stress-state and dendrite growth. Tantalum-doped lithium lanthanum zirconium oxide (LLZTO, Li6.4La3Zr1.4Ta0.6O12) is synthesized by powder processing and sintering (AS), or with the incorporation of intermediate-stage high-energy milling (M). The M compact displays higher density (91.5% vs 82.5% of theoretical), and per quantitative stereology, lower average grain size (5.4 ± 2.6 vs 21.3 ± 11.1 µm) and lower AFM-derived RMS surface roughness contacting the Li metal (45 vs 161 nm). These differences enable symmetric M cells to electrochemically cycle at constant capacity (0.1 mAh cm−2) with enhanced critical current density (CCD) of 1.4 versus 0.3 mA cm−2. It is demonstrated that LLZTO grain size distribution and internal porosity critically affect electrical short-circuit failure, indicating the importance of electronic properties. Lithium dendrites propagate intergranularly through regions where LLZTO grains are smaller than the bulk average (7.4 ± 3.8 µm for AS in a symmetric cell, 3.1 ± 1.4 µm for M in a half-cell). Metal also accumulates in the otherwise empty pores of the sintered compact present along the dendrite path. Mechanistic modeling indicates that reaction and stress heterogeneities are interrelated, leading to current focusing and preferential plating at grain boundaries. 相似文献
33.
Shashank M Patil KR Maruthi Shrisha Naik Bajpe VM Vyshali S Sushmitha Chagalamari Akhila Ramith Ramu 《Bioinformation》2021,17(11):932
Treatment of SARS-CoV-2 targeting its RNA dependent RNA polymerase (RdRp) is of current interest. Remdesivir has been approved for the treatment of COVID-19 around the world. However, the drug has been linked with pharmacological limitations like adverse effects and reduced efficiency. Nevertheless, recent advancements have depicted molnupiravir as an effective therapeutic agent to target the SARS-CoV-2 RdRp. The drug has cleared both in vitro and in vivo screening. It is in phase-III clinical trial. Nonetheless, there are no data on themolecular binding interaction of molnupiravir with RdRp. Therefore, it is of interest to report the binding interaction of molnupiravir using molecular docking. It is also of interest to show its stability during interaction using molecular dynamics and binding free energy calculations along with drug likeliness and pharmacokinetic properties in comparison with remdesivir. 相似文献
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36.
Freya KR Swinnen Paul J Coucke Anne M De Paepe Sofie Symoens Fransiska Malfait Filomena V Gentile Luca Sangiorgi Patrizia D’Eufemia Mauro Celli Ton JTM Garretsen Cor WRJ Cremers Ingeborg JM Dhooge Els MR De Leenheer 《Orphanet journal of rare diseases》2011,6(1):1-8
Background
Neurofibromatosis 1 (NF1), a common autosomal dominant disorder, was shown in one study to be associated with a 15-year decrease in life expectancy. However, data on mortality in NF1 are limited. Our aim was to evaluate mortality in a large retrospective cohort of NF1 patients seen in France between 1980 and 2006.Methods
Consecutive NF1 patients referred to the National French Referral Center for Neurofibromatoses were included. The standardized mortality ratio (SMR) with its 95% confidence interval (CI) was calculated as the ratio of observed over expected numbers of deaths. We studied factors associated with death and causes of death.Results
Between 1980 and 2006, 1895 NF1 patients were seen. Median follow-up was 6.8 years (range, 0.4-20.6). Vital status was available for 1226 (65%) patients, of whom 1159 (94.5%) survived and 67 (5.5%) died. Overall mortality was significantly increased in the NF1 cohort (SMR, 2.02; CI, 1.6-2.6; P < 10-4). The excess mortality occurred among patients aged 10 to 20 years (SMR, 5.2; CI, 2.6-9.3; P < 10-4) and 20 to 40 years (SMR, 4.1; 2.8-5.8; P < 10-4). Significant excess mortality was found in both males and females. In the 10-20 year age group, females had a significant increase in mortality compared to males (SMR, 12.6; CI, 5.7-23.9; and SMR, 1.8; CI, 0.2-6.4; respectively). The cause of death was available for 58 (86.6%) patients; malignant nerve sheath tumor was the main cause of death (60%).Conclusions
We found significantly increased SMRs indicating excess mortality in NF1 patients compared to the general population. The definitive diagnosis of NF1 in all patients is a strength of our study, and the high rate of death related to malignant transformation is consistent with previous work. The retrospective design and hospital-based recruitment are limitations of our study. Mortality was significantly increased in NF1 patients aged 10 to 40 years and tended to be higher in females than in males. 相似文献37.
Facile labeling of oligosaccharides (acidic and neutral) in a nonselective
manner was achieved with highly fluorescent anthranilic acid (AA,
2-aminobenzoic acid) (more than twice the intensity of 2- aminobenzamide,
AB) for specific detection at very high sensitivity. Quantitative labeling
in acetate-borate buffered methanol (approximately pH 5.0) at 80 degreesC
for 60 min resulted in negligible or no desialylation of the
oligosaccharides. A high resolution high performance liquid chromatographic
method was developed for quantitative oligosaccharide mapping on a
polymeric-NH2bonded (Astec) column operating under normal phase and anion
exchange (NP-HPAEC) conditions. For isolation of oligosaccharides from the
map by simple evaporation, the chromatographic conditions developed use
volatile acetic acid-triethylamine buffer (approximately pH 4.0) systems.
The mapping and characterization technology was developed using well
characterized standard glycoproteins. The fluorescent oligosaccharide maps
were similar to the maps obtained by the high pH anion-exchange
chromatography with pulsed amperometric detection (HPAEC-PAD), except that
the fluorescent maps contained more defined peaks. In the map, the
oligosaccharides separated into groups based on charge, size, linkage, and
overall structure in a manner similar to HPAEC-PAD with contribution of
-COOH function from the label, anthranilic acid. However, selectivity of
the column for sialic acid linkages was different. A second dimension
normal phase HPLC (NP-HPLC) method was developed on an amide column (TSK
Gel amide-80) for separation of the AA labeled neutral complex type and
isomeric structures of high mannose type oligosaccharides. The
oligosaccharides labeled with AA are compatible with biochemical and
biophysical techniques, and use of matrix assisted laser desorption mass
spectrometry for rapid determination of oligosaccharide mass map of
glycoproteins is demonstrated. High resolution of NP-HPAEC and NP-HPLC
methods combined with mass spectrometry (MALDI-TOF) can provide an
effective technology for analyzing a wide repertoire of oligosaccharide
structures and for determining the action of both transferases and
glycosidases.
相似文献
38.
MOTIVATION: Molecular biology databases hold a large number of empirical
facts about many different aspects of biological entities. That data is
static in the sense that one cannot ask a database 'What effect has protein
A on gene B?' or 'Do gene A and gene B interact, and if so, how?'. Those
questions require an explicit model of the target organism. Traditionally,
biochemical systems are modelled using kinetics and differential equations
in a quantitative simulator. For many biological processes however,
detailed quantitative information is not available, only qualitative or
fuzzy statements about the nature of interactions. RESULTS: We designed and
implemented a qualitative simulation model of lambda phage growth control
in Escherichia coli based on the existing simulation environment QSim.
Qualitative reasoning can serve as the basis for automatic transformation
of contents of genomic databases into interactive modelling systems that
can reason about the relations and interactions of biological entities.
相似文献
39.
Physical changes in landscapes alter the abundance and distribution of species. Higher-order effects can occur when changes in ecological processes result in altered interspecific interactions and subsequent changes in a species' abundance or persistence. Baylisascaris procyonis , a roundworm parasite of raccoons ( Procyon lotor ), is pathogenic to numerous small vertebrates that serve as intermediate hosts, including white-footed mice ( Peromyscus leucopus ). Raccoons have responded positively to agriculturally induced changes in landscapes, with potential consequences for intermediate hosts of B . procyonis . We examined white-footed mice from a homogeneous, predominantly forested landscape in south-central Indiana and a heterogeneous, predominantly agricultural landscape in northwestern Indiana for presence of larval B . procyonis . We compared prevalence of infection, intensity of infection, and average number of larvae per mouse between the landscapes, and among forest patches within the highly fragmented agricultural landscape. Prevalence, intensity of infection, and average number of larvae were significantly higher in the highly fragmented landscape. Within the agricultural landscape, regression models predicted probability of infection, intensity of infection, and average number of larvae per mouse per patch as functions of forest patch area and isolation. We conclude that positive responses of raccoons to agriculturally induced fragmentation of forests have resulted in increased encounter rates between white-footed mice and infective stages of B . procyonis between and within landscapes, resulting in increased transmission of the parasite to intermediate hosts. 相似文献
40.
The inhibitory effect of 23N-alkyl-4-piperidylesters (alkyl = ethyl-butyl) (APEA) and 8N-ethyl-2-pyrrolidinylmethylesters (EPMEA) of 2- and 3-substituted alkoxyphenylcarbamic acids (alkoxy = butoxy-heptyloxy-) on photosynthetic Hill reaction activity of spinach chloroplasts and on chlorophyll (Chl) synthesis in green algaeChlorella vulgaris was investigated. Inhibitory activities of these compounds were strongly connected with the lipophilicity of the whole molecule. A lower inhibitory activity of 2-alkoxy-substituted derivatives in relation to the corresponding 3-substituted ones was confirmed. Electron spin resonance (ESR) spectra of spinach chloroplasts demonstrated that the studied compounds affected the structure of photosystem (PS) 2 with the release of Mn2+ ions into interior of thylakoid membranes. 相似文献