Biodegradation of plant cell walls,wall carbohydrates,and wall aromatics in wheat grown in ambient or enriched CO2 concentrations

Mature internodes from wheat (Triticum aestivum L) grown in control (ambient at c 370 μnol mol^?1) or enriched (to 550 μmol mol^?1) concentrations of atmospheric CO₂ in the free-air CO₂ enrichment (FACE) system were analyzed for potential changes in biodegradation of constituents due to predicted increases in atmospheric levels of CO₂. The first internodes below the grain were incubated with the lignocellulose-degrading white rot fungus, Phanerochaete chrysosporium K-3, or incubated without microorganisms. Plant samples were then analyzed for dry weight loss, disposition of specific cell types to biodegradation using electron microscopy, carbohydrates and lignin using solid state NMR spectroscopy, and ester-and ether-linked aromatics using gas chromatography. Phanerochaete chrysosporium extensively degraded stems cells (c 75%) and both carbohydrate and aromatic portions of the wheat stems; proportionately more carbohydrates were removed by the fungus from the stems. Enriched CO₂ did not affect the chemical composition of wheat stems or the biodegradation by P chrysosporium of plant cell walls or wall components for the most part. Data from various methods all indicated that enriched CO₂ did not substantially alter the biodegradation of wheat cell wall internodes or wall components. Evidence was not found for an influence on C cycling due to CO₂ concentrations in this study.     

Effect of hyperbaric oxygenation on experimental pancreas necrosis in pigs

A pancreatic necrosis was produced in 7 piglets by means of a sodiumdesoxycholacid trypsin mixture. 4 animals served as control. All animals get a basis-infusion therapy. Hyperbaric oxygen therapy (HBO) was applied additionally in 3 animals. All control animals survived. The three animals with HBO deceased in average after 22 days, those without HBO deceased already after 4.25 days. Laboratory and circulatory measures show no significant differences. The autopsy statements were different from the age of necrosis. The conclusion by the extension of the average survival time in experimental pancreatic necrosis by means of HBO is that the high lethality of the pancreatic necrosis can be reduced by means of HBO.     

Discrimination of growth and water stress in wheat by various vegetation indices through clear and turbid atmospheres

Reflectance data were obtained over a drought-stressed and a well-watered wheat plot with a hand-held radiometer having bands similar to the MSS bands of the Landsat satellites. Data for 48 clear days were interpolated to yield reflectance values for each day of the growing season, from planting until harvest. With an atmospheric path radiance model and Landsat 2 calibration data, the reflectances were used to simulate Landsat digital counts (not quantized) for the four Landsat bands for each day of the growing season, through a clear ($\text{?100-}\text{km}$ meteorological range) and a turbid ($\text{?10-}\text{km}$ meteorological range) atmosphere. Several ratios and linear combinations of bands were calculated using the simulated data, then assessed for their relative ability to discriminate vegetative growth and plant stress through the two atmospheres. The results showed that water stress was not detected by any of the indices until after growth was retarded, and the sensitivity of the various indices to vegetation depended on plant growth stage and atmospheric path radiance.     

基于粒子群优化的板球系统双闭环滑模控制

板球系统是高阶、开环不稳定的非线性系统,本文基于板球系统简化模型,结合Lyapunov稳定性原理,在双闭环控制方案的基础上,设计滑模变结构位置控制器,并使用粒子群算法对滑模界面参数和滑模趋近律参数进行优化,提高了控制精度,减消了滑模抖振。仿真实验表明,与传统双闭环PID控制相比,滑模变结构控制算法响应速度更快,达到稳定状态时间更短,具有更好的跟踪与鲁棒性能。     

Unifying Principles in Zeolite Chemistry and Catalysis

Abstract

In recent years molecular sieve catalysts have assumed an increasingly important role in industrial catalysis, Applications of zeolite catalysts are expanding from the traditional petroleum refining to new and improved fuel processing applications, and to new roles in both the petrochemical and chemical industries. Up to the present, all commercial applications of zeolite catalysts have been carried out with aciaic zeolites. Recent investigations of zeolite chemistry revealed several important features which appear common to both alkali and acidic zeolites. This new chemical evidence raises the possibility that the underlying physicochemical features of both types of zeolites play a role in catalysis.     

A fracture mechanics concept for the accelerated characterization of creep crack growth in PE-HD pipe grades

For the lifetime prediction of pressurized polyethylene (PE) pipes based on methods of the linear elastic fracture mechanics the knowledge of the crack resistance and the kinetics of creep crack growth (CCG) is essential. In the present work a rather brittle nonpipe material was used to develop a methodology for an accelerated measurement of crack kinetics in fatigue tests on cracked round bar (CRB) specimens at ambient temperatures of 23 °C. A material and specimen specific compliance calibration curve was generated to detect the crack kinetics with only one single CRB test. Based on an already proposed concept the kinetics at different R-ratios (minimum/maximum load) was measured and extrapolated to the case of CCG. To demonstrate the transferability of this concept to pipe materials a PE 80 pipe grade was used. Although the necessary testing time increased considerably the concept still has the potential to reduce the overall testing time for new pipe materials to be certified significantly. With the presented procedure a characterization of CCG in modern PE pipe grades at room temperature and without the use of stress cracking liquids is possible within a few months.     

Impact Optimization of 3D‐Printed Poly(methyl methacrylate) for Cranial Implants

Material extrusion‐based additive manufacturing, also known as fused filament fabrication (FFF) or 3D printing facilitates the fabrication of cranial implants with different materials and complex internal structures. The impact behavior plays a key role in the designing process of cranial implants. Therefore, the performance of impact tests on novel implant materials is of utmost importance. This research focuses on investigating the dependency of the infill density and pattern on the impact properties of 3D‐printed poly(methyl methacrylate) (PMMA) sandwich specimens including internal rectilinear, gyroid, and 3D‐honeycomb (3D‐HC) structures. 3D‐HC structures show higher impact forces and dissipated energies as well as dynamic stiffness values compared to rectilinear and gyroid structures at the same infill density. 70% infill 3D‐HC and 100% infill rectilinear structures prove to be most promising. In addition, two different optimization techniques to further improve the impact properties of these specimens, namely a material and a topology optimization, are applied. Topology optimization shows promising results until first damage and material optimization regarding dissipated energies. However, both are not able to outperform the 3D‐HC pattern.     

Regenerated dorsal root fibers form functional synapses in embryonic spinal cord transplants

1. The aim of the present study was to determine whether synapses formed by dorsal root afferents that regenerate into intraspinal transplants of fetal spinal cord are functional. Severed L4 or L5 dorsal root stumps were placed at the bottom of dorsal quadrant cavities made in the lumbar spinal cords of adult rats and juxtaposed to embryonic day 14 spinal cord transplants. 2. In animals examined 5-10 weeks later, we recorded extracellularly in transplants from 43 units that fired in response to electrical stimulation of the implanted dorsal root. Latency fluctuations of extracellular firing that increase with stimulus and failure to follow high-frequency and posttetanic potentiation of extracellular firing stimulation suggest that synapses with conventional properties are formed between regenerating afferents and transplant neurons. Limited intracellular recordings confirmed the existence of excitatory postsynaptic potentials in transplant neurons after dorsal root stimulation. 3. In 16 units, extracellular firing occurred in response to single shock stimulation. The remainder of the units required two or more dorsal root shocks to evoke firing; some of these connections also may be monosynaptic. 4. Under the assumption that single shock firing was most likely the result of monosynaptic connections between transplant neurons and regenerated dorsal root fibers, we estimated the conduction velocities of regenerated fibers. These estimates suggest that fibers with conduction velocities in the C, A delta, and A alpha/beta ranges regenerate into transplants of embryonic spinal cord. 5. The results demonstrate that regenerated dorsal root axons establish functional synaptic connections with transplant neurons. The implications for using fetal transplants to help rebuild spinal reflex circuits after spinal cord injury are considered.     

A novel antibody-dependent cellular cytotoxicity epitope in gp120 is identified by two monoclonal antibodies isolated from a long-term survivor of human immunodeficiency virus type 1 infection

Two monoclonal antibodies (MAbs), 42F and 43F, were isolated some 14 months apart from a single long-term survivor of human immunodeficiency virus type 1 (HIV-1) infection. These MAbs were found to be indistinguishable in terms of their isotypes, specificities, affinities, and biological activities. Both 42F and 43F directed substantial antibody-dependent cellular cytotoxicity (ADCC) against cells infected with four divergent lab-adapted strains of HIV-1, but no neutralizing activity against these strains was detectable. The ability of MAbs 42F and 43F, as well as that of MAbs against two other gp120 epitopes, to direct ADCC against uninfected CD4+ cells to which recombinant gp120SF2 had been adsorbed (i.e., "innocent bystanders") was demonstrated to be less efficient by at least an order of magnitude than their ability to direct ADCC against HIV-1-infected cells. Flow cytometry analyses showed that 42F and 43F also bind to native primary isolate Envs from clades B and E expressed on cell surfaces. By direct binding and competition assays, it was demonstrated that the 42F/43F epitope lies in a domain of gp120 outside the previously described CD4-binding site and V3 loop ADCC epitope clusters. Immunoblot analysis revealed that the 42F/43F epitope is not dependent on disulfide bonds or N-linked glycans in gp120. Epitope mapping of 42F and 43F by binding to linear peptides demonstrated specificity of these MAbs for a sequence of 10 amino acids in the C5 domain comprising residues 491 to 500 (Los Alamos National Laboratory numbering for the HXB2 strain). Thus, 42F and 43F define a new ADCC epitope in gp120. Because of the relative conservation of this epitope and the fact that it appears to have been significantly immunogenic in the individual from which these MAbs were derived, it may prove to be a useful component of HIV vaccines. Furthermore, these MAbs may be used as tools to probe the potential importance of ADCC as an antiviral activity in HIV-1 infection.