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ABSTRACTThe effects of flame remelting on the microstructural features, mechanical properties and dry sliding wear properties of supersonic plasma sprayed NiCrBSi-30 wt-% Mo coating were evaluated. The modified microstructure of the flame remelted coating, such as reduction in micro-defects, decrease in line roughness, laminar architecture elimination and material homogenisation was obtained. The Vickers micro-hardness and elastic modulus measurement showed an enhancement for flame remelted coating. The main wear mechanism of the as-sprayed coating was adhesive/delaminative wear. While the main wear mechanism of the flame remelted coating was adhesive wear. The wear resistance of flame remelted coating surpassed that of the as-sprayed coating and was by far superior to the substrate.

The effects of flame remelting on the microstructural features, mechanical properties and dry sliding wear properties of supersonic plasma sprayed NiCrBSi-30 wt-% Mo coating were evaluated. The modified microstructure of the flame remelted coating, such as reduction in micro-defects, decrease in line roughness, laminar architecture elimination and material homogenisation was obtained. The Vickers micro-hardness and elastic modulus measurement showed an enhancement for flame remelted coating. The main wear mechanism of the as-sprayed coating was adhesive/delaminative wear. While the main wear mechanism of the flame remelted coating was adhesive wear. The wear resistance of flame remelted coating surpassed that of the as-sprayed coating and was by far superior to the substrate.

We present the first in situ observations of a small-scale flux rope locally formed at the separatrix region of magnetic reconnection without large guide field. Bidirectional electron beams (cold and hot beams) and density cavity accompanied by intense wave activity substantiate the crossing of the separatrix region. Density compression and one parallel electron beam are detected inside the flux rope. We suggest that this flux rope is locally generated at the separatrix region due to the tearing instability within the separatrix current layer. This observation sheds new light on the 3-D picture of magnetic reconnection in space plasma. Flux rope is observed at separatrixFlux rope is locally generated by tearing instabilityThis observation sheds new light on the 3-D picture of magnetic reconnection

An amperometric glucose biosensor was prepared using polyaniline (PANI) and chitosan-coupled carbon nanotubes (CS-CNTs) as the signal amplifiers and glucose oxidase (GOD) as the glucose detector on a gold electrode (the Au-g-PANI-c-(CS-CNTs)-GOD biosensor). The PANI layer was prepared via oxidative graft polymerization of aniline from the gold electrode surface premodified by self-assembled monolayer of 4-aminothiophenol. CS-CNTs were covalently coupled to the PANI-modified gold substrate using glutaradehyde as a bifunctional linker. GOD was then covalently bonded to the pendant hydroxyl groups of chitosan using 1,4-carbonyldiimidazole as the bifunctional linker. The surface functionalization processes were ascertained by X-ray photoelectron spectroscopy (XPS) analyses. The field emission scanning electron microscopy (FESEM) images of the Au-g-PANI-c-(CS-CNTs) electrode revealed the formation of a three-dimensional surface network structure. The electrode could thus provide a more spatially biocompatible microenvironment to enhance the amount and biocatalytic activity of the immobilized enzyme and to better mediate the electron transfer. The resulting Au-g-PANI-c-(CS-CNTs)-GOD biosensor exhibited a linear response to glucose in the concentration range of 1−20 mM, good sensitivity (21 μA/(mM·cm2)), good reproducibility, and retention of >80% of the initial response current after 2 months of storage.

Solid lubrication composite FeCrBSi/FeS layer was prepared by compound technology – combining supersonic velocity plasma spray with low-temperature ion sulphurizing. X-ray diffraction pattern for the composite layer implied that the layer mainly consists of α-Fe and FeS. Scanning electron microscopy was used to observe the surface, cross-section, and worn scar morphologies of the FeCrBSi/FeS layer. The nano-hardness and elastic modulus of the layer were surveyed by a nano-indentation tester. The sliding tribological behaviour of the FeCrBSi/FeS layer and the original 1045 steel against 52 100 steel counterparts was studied under dry and oil lubrication conditions by ball-on-disc tests. The experimental results showed that the composite FeCrBSi/FeS layer exhibited remarkable friction-reducing effects and obvious wear resistance under dry and oil lubrication conditions.

This study investigated the transfection ability and efficiency of liposomes and immunoliposomes for exogenous gene delivery into the brain via the venous system. Four groups of rats underwent tail vein injection with one of the following: liposomes encapsulating pCMV (human cytomegalovirus promoter)-LacZ plasmid 80 μg (low dose) or 300 μg (high dose); general immunoliposomes encapsulating 80 μg transferrin receptor antibodies (OX26)-pCMV-LacZ plasmid; or brain-specific immunoliposomes encapsulating 80 μg OX26-pGFAP (glial fibrillary acidic protein promoter)-LacZ plasmid. A control group received no injected agent. The LacZ mRNA levels (1 h post-injection) and β-galactosidase activity (48 h post-injection) in the brain and peripheral organs were assayed using real-time reverse transcription–polymerase chain reaction and histochemical staining, respectively. Both immunoliposomes delivered exogenous DNA containing the LacZgene into the brain after venous injection, resulting in extensive LacZexpression in the brain. Furthermore, the brain-specific OX26-pGFAP-LacZ immunoliposome decreased the non-specific expression of LacZin peripheral organs without affecting transfection efficiency in the brain. Thus, brain-specific immunoliposomes are an efficient and brain-specific targeting vector.

A density functional theory study was carried out on the structures and harmonic vibrational frequencies of the low-lying states of CrO2using several density functional methods with various basis sets of different quality including all-electron basis sets (3-21G and 6-311+G*) and effective core potentials ones. At all levels of calculations employed, the inserted dioxide with 3B1state in C2vsymmetry is found to be the most stable. Other low-lying stable states with possible side-on, end-on and inserted structures were also located on the potential energy surface of CrO2. The results obtained here are in fair agreement with experimental data, when available, and serve as predictions otherwise.

Abstract: We evaluated by in situ nick end labeling the presence of apoptotic glial cells in the spinal cord of rats which have sustained a moderate and severe compression injury at the level of T8–9, resulting in a severe but reversible paraparesis and irreversible paraplegia, respectively. In a previous investigation we found apoptotic glial cells (oligodendrocytes) in the immediate vicinity of the primary lesion (T7 and T10). The present study was designed to evaluate the extent of such cells in the spinal cord even at long distances away from the primary injury. Rats sustaining a moderate and severe compression injury and surviving 4 and 9 days showed a significant increase in the number of apoptotic glial cells at the T1, T5, T7, T12 and L2 levels. At the T10 level the elevation was significant only after day 9. There was no significant increase in the number of these cells at 4 h and 1 day after moderate and severe compression. In general, the apoptotic cells were most often seen in segments adjacent to the compression. They were randomly located in the ventral, lateral and dorsal tracts but were rarely present in the gray matter of the cord. In conclusion, compression trauma to rat spinal cord induces signs of apoptosis in glial cells, presumably oligodendrocytes of the long tracts. This newly discovered type of secondary injury is widely distributed in the damaged spinal cord and occurs even at long distances remote from the initial compression injury. Apoptotic cell death of oligodendrocytes will induce myelin degeneration and cause additional disturbances of axonal function. This cell damage may be a target for future therapy since it occurs after a delay and chemical compounds are now available by which apoptotic cell death can be modified.

The reaction kinetics of hydrogen ions with gibbsite, goethite, kaolinite, and three electrodialyzed variable charge soils were studied by monitoring the decrease in Hion concentration and the increases in soluble aluminum and positive surface charge. The Hion concentration: dropped sharply within 5 s and then remained practically unchanged for goethite; showed a marked decrease after the rapid reaction stage for gibbsite; and changed only very slowly for kaolinite. For soils, there were also a rapid reaction stage and a slow reaction stage. The magnitude of the increase in positive surface charge was of the order Hapludox > Kanhapludult > Paleudult, while that of the increase in soluble aluminum was of the order Paleudult > Hapludox > Kanhapludult. These phenomena were interpreted in terms of the protonation of surface -Fe-OH groups (a rapid reaction) and the dissolution of aluminum-containing minerals (a slow reaction). The addition of iron oxides to the soil or the removal of free iron oxides from the soil affected the reaction kinetics markedly. The reaction kinetics can be described by parabolic diffusion equation, Elovich equation, and two-constant rate equation fairly well, with the degree of fitness depending on the initial concentration of Hions.

Urinary phenol determinations have traditionally been used to monitor high levels of occupational benzene exposure, but the same technique cannot be used to monitor low-level exposures because of the high background of phenol resulting from its Presence in many foods and from metabolism of aromatic amino acids. Thus, new biological indexes for exposure to low levels of benzene are needed. Animal studies indicate that muconic acid is a metabolite of benzene that is excreted in the urine as an increasing fraction of the total benzene metabolites with decreasing dose of benzene. Thus, urinary muconic acid is potentially useful as a monitor for low levels of exposure to benzene. It is also of interest to determine the level of muconic acid in the urine of humans exposed to benzene for comparison with animal data as an aid for use of the animal studies in risk assessments for humans. This report describes the development of a gas chromatographylmass spectrometry assay to detect and quantitate the benzene metabolise, muconic acid, in urine. The internal standard used in the assay, muconic acid-d4, was biosynthesized bY F344/N rats administered benzene-d6 by gavage; the muconic acid was isolated from the rat's urine. Muconic acid was measured in experimental urine samples by adding the internal stalldard, followed by extraction and derivatization. Phenol was also measured in urine after extraction and derivatization. The assays were applied to the urine samples from 14 workers occupationally exposed to benzene and 8 workers with no known benlene exposure. Muconic acid could be detected in all of the urine samples at levels greater than 100 ng/mL. A linear correlation could be fitted to the time-weighted average (TWA) benzene concentrations, as measured by room air monitoring, and muconic acid in urine (R=0.9). Workers exposed to benzene concentrations of as little as 4.4 ppm over an 8-hr day possessed higher urinary muconic acid concentrations than did any control individual (p<0.005). In contrast, no significant difference could be detected for urinary phenol between exposed and control workers at these levels. The ratio between muconic acid and phenol in the urine of the workers exposed to benzene (0.38) was similar to that observed in rats (0.31), but not mice (0.62), exposed to similar amounts of benzene. The assay for muconic acid may potentially be useful as a biological exposure index for benzene at levels approaching the current American Conference of Governmental Industrial Hygienists' threshold limit value (TLY) of 1 ppm; however, improved knowledge of the excretion of muconic acid as a function of both dose and time after exposure will need to be made.

Abstract:  Experiments were carried out to study the effects of imperfect spatial resolution on turbulence measurements in the very near-wall region using hot wires of different lengths, l + (in wall units). Previous works have indicated that the distributions of the longitudinal velocity rms value, skewness and flatness factors are independent of l + in the buffer region and beyond provided l +<20–25. Our results obtained using l +=3, 6, and 22 in the viscous sublayer region show that generally the said distributions are dependent on l + and attentuate in magnitude with increasing l +. Further experiments were also carried out at different Reynolds numbers (Re c , based on centerline velocity and channel’s height) but with measurements made using hot wire of the same l +. The latter shows that the rms value and other higher order moments of longitudinal velocity fluctuations are independent of Re c , thereby extending similar findings by Johansson and Alfredsson (1983), valid in the buffer region into the viscous sublayer region.

Occupational exposure to benzene is known to cause leukemia, but the mechanism remains unclear. Unlike most other carcinogens, benzene and its metabolites are weakly or nonmutagenic in most simple gene mutation assays. Benzene and its metabolites do, however, produce chromosomal damage in a variety of systems. Here, we have used the glycophorin A (GPA) gene loss mutation assay to evaluate the nature of DNA damage produced by benzene in 24 workers heavily exposed to benzene and 23 matched control individuals in Shanghai, China. The GPA assay identifies stem cell or precursor erythroid cell mutations expressed in peripheral erythrocytes of MN-heterozygous subjects, distinguishing the NN and N phi mutant variants. A significant increase in the NN GPA variant cell frequency (Vf) was found in benzene-exposed workers as compared with unexposed control individuals (mean +/- SEM, 13.9 +/- 1.7 per million cells vs. 7.4 +/- 1.1 per million cells in control individuals; P = 0.0002). In contrast, no significant difference existed between the two groups for the N phi Vf (9.1 +/- 0.9 vs. 8.8 +/- 1.8 per million cells; P = 0.21). Further, lifetime cumulative occupational exposure to benzene was associated with the NN Vf (P = 0.005) but not with the N phi Vf (P = 0.31), suggesting that NN mutations occur in longer-lived bone marrow stem cells. NN variants result from loss of the GPA M allele and duplication of the N allele, presumably through recombination mechanisms, whereas NO variants arise from gene inactivation, presumably due to point mutations and deletions. Thus, these results suggest that benzene produces gene-duplicating mutations but does not produce gene-inactivating mutations at the GPA locus in bone marrow cells of humans exposed to high benzene levels. This finding is consistent with data on the genetic toxicology of benzene and its metabolites and adds further weight to the hypothesis that chromosome damage and mitotic recombination are important in benzene-induced leukemia.

Abstract: We evaluated by immunohistochemistry the presence of β-amyloid precursor protein (ßAPP) and ubiquitin-like material which may accumulate in axons of the human spinal cord subjected to injury. Autopsy material was obtained from nine cases with different types of trauma: breech delivery with neonatal spinal injury, compression of the cord induced by fractures of the vertebral column, haematomas or intradural meningioma. The post-trauma period ranged from 10 days to several years. The spinal cord of six control cases without evidence of injury presented βAPP immunoreactivity in nerve cell bodies and in a few axonal profiles but not in dendrites. Seven of the nine cases with spinal cord trauma showed an accumulation of βAPP-immunoreactive material in axons of the longitudinal tracts at the site of the injury. Five cases presented similar axonal immunoreactivity in the grey matter of the cord. Ubiquitin-like immunoreactivity was present in expanded axons in cases with spinal cord injury. Cases with spinal cord trauma thus present βAPP-immunoreactive axons particularly of the longitudinal tracts in the same way as in trauma to rat spinal cord and in various brain injuries. The aggregation of βAPP-immunoreactive material indicates disturbed axonal transport of βAPP. Accumulation of ubiquitin-like immunoreactive material in expanded axons at the site of trauma may be one prerequisite for degradation of abnormal proteins by the ubiquitin-mediated proteolytic pathway.

Abstract: Growth-associated protein 43 (GAP43) is one compound used to indicate growth of axonal endings during development and regeneration, particularly of peripheral neurons. Using immunohistochemistry, we have studied the expression of GAP43 in the spinal cord of rats subjected to mild, moderate or severe compression injury and used neurofilament immunostaining to demonstrate axonal injuries. Samples removed from the compressed T8–9, the cranial T7 and the caudal T10 segments were studied at 4 h, 24 h, 4 days and 9 days after injury. Control rats showed a moderate immunostaining of neurons in dorsal root ganglia, weak staining of ventral motor neurons and, with the exception of the corticospinal tracts, a weak staining in some axons of the longitudinal tracts of the cord. Injury in the compressed region led to increased GAP43 immunoreactivity in axons of normal and expanded size. This occurred particularly 1–4 days after injury and normalized 9 days thereafter. More marked immunostaining was present in the cranial and caudal segments. The corticospinal tracts never showed such staining. The increase of GAP43 immunostaining is presumably caused by disturbed axonal transport from neurons with the capacity to synthesize and transport the GAP43 antigen. Transported material may thus be available for regeneration of axons, but this source of material may vary between different classes of axons within the cord.

The ubiquitin-mediated proteolytic pathway is an important mode of protein degradation in various tissues. Since breakdown of proteins may occur in axons after injury we evaluated the presence of ubiquitin-like immunoreactive material in rat spinal cord following compression injury of mild, moderate and severe degrees at T8-9 level, resulting in no neurological deficit, reversible paraparesis and paraplegia of the hind limbs, respectively. Rats with mild to severe compression injury surviving 1–4 days showed numerous, intensely immunoreactive expanded axons at the site of compression. The labelled axons were randomly distributed in the longitudinal tracts but they were never found in the corticospinal tracts. No labelling was detected by 9 days after injury. In addition, the presence of labelled axons was investigated in the T7 and the T10 segments from rats with moderate compression. No labelling was seen in T7, but in T10 segments many immunoreactive axons were present. Control rats did not show immunoreactive axons in the spinal cord. Neurons of dorsal root ganglia, trigeminal ganglia and of the grey matter of the spinal cord were immunoreactive. Cerebral cortical neurons did not show ubiquitin expression. Thus, compression of the rat spinal cord causes a transient accumulation of ubiquitin-like immunoreactive material in axonal swellings. Even though the dynamics of ubiquitin conjugates are not fully understood, the observed axonal accumulation presumably reflects arrested anterograde axonal transport of protein chiefly derived from neurons of dorsal root ganglia and the local neurons of the spinal cord. The presence of ubiquitin in damaged axons is one prerequisite for degradation of abnormal proteins by the ubiquitin-mediated proteolytic pathway, which may be activated in reactive axonal swellings.

Female Wistar rats were exposed to various solvent vapors 8 h/d for 7 d. The leukocyte suspension and serum were prepared from peripheral blood and utilized for the determination of alkaline phosphatase (AP) activity with disodium phenyl phosphate as a substrate [leukocyte AP (LAP) and serum AP (SAP) assay]. While the exposure to benzene at 20 or 50 ppm did not cause significant changes in LAP activity, the exposure at 100 and 300 ppm resulted in a dose-dependent increase of LAP activity up to more than 700% over the control. No further increase was observed at 1000 or 3000 ppm. Similar exposure at 300 ppm to either toluene, m-xylene, n-hexane, trichloro-ethylene, methyl ethyl ketone, ethyl acetate, or methyl alcohol did not induce any changes in LAP activity. Thus, the increase in LAP activity was considered to be specific to benzene exposure. When the animals were exposed to toluene (300 ppm) in combination with benzene (300 ppm), not only was the benzene-induced leukopenia alleviated as previously reported, but the benzene-induced increase in LAP activity was no longer observed. The parallel inhibitory effects of toluene on benzene-induced increase in LAP and leukopenia suggest that a relation may exist between increase in LAP activity and leukopenia. No changes in SAP activities were observed in the rats under the exposure conditions examined.

Knowing how nutrients are distributed within fruit tree cultivars can lead to better nutrient source, rate, time and place decisions that, in turn, will support tree health and the nutritive value of their fruit. This study detected differences in nutrient need between two cultivars of widespread use, and identified some specific management strategies to address these differences. [ABSTRACT FROM AUTHOR]

Chemical examination of roots of Maackia tenuifolia yielded three new isoflavans, manuifolins D, E, and F, along with the known (6aR,12aR)-pterocarpin and (6aR,l2aR)-maackiain. The new compounds were established as (3R)-5‘-(1,1-dimethyl-2-propenyl)-4‘-O-(3-methyl-2-butenyl)-7,2‘-dihydroxyisoflavan (1), (3R)-6,5‘-bis(1,1-dimethyl-2-propenyl)-7,2‘,4‘,-trihydroxyisoflavan (2), and (3R)-5‘-(1-isopropylethenyl)-8-(3-methyl-2-butenyl)-7,2‘,4‘-trihydroxyisoflavan (3), respectively, by spectroscopic methods.

Macadamia nut produces plenty of residues after oil extraction which exhibit considerable quantities of protein and other nutrients. These residues, if not dealt with, become environmental pollutants and meanwhile lead to a great waste of resources. In this study, proteins were isolated from the residues of Macadamia nuts using the method of aqueous alkaline extraction at pH 9 and the identification of Amino acids was performed by cation-exchange chromatography. Box-Behnken Design (BBD) was used here, as an experimental method, to estimate and optimize the yield of protein. The results showed that 22.49% proteins were extracted under the optimized conditions. 18 Amino acids including 7 essential ones which took up 22.46% (Tryptophan was not detectable) could be found in it and was much higher than that in peanut meal, soybean meal and rapeseed meal, especially Glu, Arg, Asp and Gly whose content were up to 164.35 mg/g, 117.77 mg/g, 96.72 mg/g and 67.19 mg/g respectively.

Two new dichromenes, 1 and 2, were isolated from the aerial parts of Evodia lepta. Their structures were determined by spectroscopic analysis.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.