Search

We report the synthesis and fatigue characterization of fiberglass/epoxy composites with various weight fractions of graphene platelets infiltrated into the epoxy resin as well as directly spray-coated on to the glass microfibers. Remarkably only ∼0.2% (with respect to the epoxy resin weight and ∼0.02% with respect to the entire laminate weight) of graphene additives enhanced the fatigue life of the composite in the flexural bending mode by up to 1200-fold. By contrast, under uniaxial tensile fatigue conditions, the graphene fillers resulted in ∼3−5-fold increase in fatigue life. The fatigue life increase (in the flexural bending mode) with graphene additives was ∼1−2 orders of magnitude superior to those obtained using carbon nanotubes. In situ ultrasound analysis of the nanocomposite during the cyclic fatigue test suggests that the graphene network toughens the fiberglass/epoxy-matrix interface and prevents the delamination/buckling of the glass microfibers under compressive stress. Such fatigue-resistant hierarchical materials show potential to improve the safety, reliability, and cost effectiveness of fiber-reinforced composites that are increasingly the material of choice in the aerospace, automotive, marine, sports, biomedical, and wind energy industries.

Micro electrical discharge machining (EDM) has the ability to drill micro holes with high accuracy in metallic materials. The aspect ratio of a micro hole generated by micro EDM is usually higher than those by other processes such as etching, mechanical drilling, and laser. However, it was found that the drilling speed of micro EDM slows down and even stops when the aspect ratio reaches a certain value. To understand this phenomenon, a theoretical model is proposed based on the fluid mechanics and surface tension. Experiments under different machining conditions are carried to verify this model. Experimental results agree with the theoretical values, which indicate the validity of the proposed model. The difference between the theoretical values and the real values might be caused by the debris and the temperature in the discharge gap, which are ignored in the model.

To investigate the short-term effects of laser-assisted subepithelial keratectomy (LASEK) on the corneal endothelium, 10 patients undergoing LASEK for myopia without complications (20 eyes) were observed. Each eye was evaluated by slit-lamp biomicroscopy and non-contact specular microscopy pre-operatively, and at 15 min, 1 day and 1 week post-operatively. The decrease in endothelial cell density was statistically significant at 15 min post-operatively, and the difference between pre-operative and 15-min post-operative coefficient of variation of cell size was also statistically significant. The percentage of hexagonal cells was significantly different from baseline levels at 15 min and at 1 day post-operatively. All parameters at 1 week post-operatively were not statistically different from those observed pre-operatively. Immediate changes in endothelial cell number and morphology occurred following LASEK, but endothelial morphology returned to the pre-operative condition after 1 week. Long-term follow-up is needed to identify further consequences of this procedure.

Nb/NiZr composite alloy membranes have been reported to have hydrogen permeabilities higher than that of pure Pd. Since the hydrogen permeation behaviour in these composite alloys is highly microstructure sensitive, hydrogen permeability is likely to depend on annealing conditions. This work has looked into the effect of annealing on the hydrogen permeability of as-cast Nb-Ni-Zr alloys with the goal of helping in the advancement of Nb-based alloy membranes as cost-effective alternatives to the Pd-based alloy membranes used for hydrogen purification. Nb-Ni-Zr alloy ingots of different compositions were prepared by argon arc-melting. The samples were vacuum sealed in quartz tubes and annealed isochronally for 1h between 500°C and 900°C. It was found that the samples annealed at 900°C exhibit higher hydrogen permeability than the as-cast samples. However, these samples were found to be less resistant to hydrogen embrittlement and the membrane exhibited cracks after the permeation test. The main mechanical failure mechanism was due to intragranular cracking for the alloys with high Nb content whilst the mechanism was observed to be intergranular cracking for alloys with lower Nb-content. The mode of failure did not change after annealing.

This study was designed to evaluate the functional and radiological outcomes of patients with complex tibial plateau fractures treated with double-buttress plate fixation. Sixty five cases of complex (Schatzker type V and VI) tibial plateau fractures were treated with double-buttress plate fixation in our centre from September 2001 to September 2006 through two separate plate incisions. Fifty four patients were followed up for a period ranging from 12 to 48 months and evaluated for the functional and radiological outcomes by a series of standard questionnaire and measurement. Due to the good exposure without any extensive soft-tissue dissection of the double-buttress plate fixation, the fractures in all 54 patients were healed and the treatment achieved greater than 90% of satisfactory-to-excellent rates of reduction. The mean time of bone union was 15.4 weeks (range, 12-30 weeks), and the mean time of full weight-bearing was 18.7 weeks (range, 14-26 weeks). At the final follow-up visit, no patients showed knee instability; the mean range of motion was 107.6° (range, 85°-130°). For all patients, no statistically significant difference in the functional outcomes was observed between their 6-months and final follow-up visits; or in the radiological findings between their immediate postoperative and final follow-up examinations. Double-buttress plate fixation is a feasible treatment option for bilcondylar and complex tibial plateau fractures. Although technically demanding, it offers reliable stability without additional postoperative adjuvant external fixation, and at the same time avoids extensive soft tissue dissection, allowing the early painless range of motion.

Barium oxide (BaO) was grown on a yttria-stabilized zirconia (YSZ) substrate by oxygen plasma-assisted molecular beam epitaxy. In situ reflection high-energy electron diffraction, ex situ X-ray diffraction (XRD), atomic force microscopy, and X-ray photoelectron spectroscopy (XPS) have confirmed that BaO grows as clusters on YSZ(111). During and following growth under ultrahigh vacuum conditions, we found BaO remained in single phase. When exposed to ambient conditions, the clusters transformed to BaCO3and/or Ba(OH)2H2O. However, in a few attempts of BaO growth, XRD results show a fairly single-phase cubic BaO with a lattice constant of 0.5418(1) nm. XPS results show that exposing BaO clusters to ambient conditions resulted in the formation of BaCO3on the surface and partly Ba(OH)2throughout the bulk. On the basis of the observations, it is concluded that the BaO nanoclusters grown on YSZ(111) are highly reactive in ambient conditions.

Background: Atrial arrhythmias are common complications of hyperthyroidism, but the underlying mechanisms remain to be further clarified. Thus, in this study, we try to investigate the effects of thyroid hormone on atrial electrophysiology by using a hyperthyroidism model in vivo. Materials and methods: Twenty-four New Zealand white rabbits were randomized into Thyroxine group (no.=12) andControl group (no.=12). In Thyroxine group, Levo-thyroxine (L-T4) solution (1 mg/kg.d−1) was injected daily into the peritoneum for 2 weeks. In Control group, the same amount of saline was injected. On day 15, 8 rabbits in each group were chosen randomly to receive electrophysiological experiment in vivo, in which electrophysiological parameters and atrial arrhythmias induced by electrical stimulation were recorded and serum thyroid hormone levels were examined. The others were killed so as to exam the L-type calcium current of atrium. Results: Atrial monophasic action potential at 90 repolarization (AMAP90) and effective refractory period (AERP) were significantly shorter in Thyroxine group than in Control group (AMAP90: 103.21±1.94 vs122.14±6.13, p<0.01; AERP: 82.69±0.99 vs 102.46±2.32, p<0.01). There are significant differences in the incidence of atrial arrhythmias between the two groups. The mean peak of L-type calcium current (ICa,L) densities (pA/pF) at −10mV was significantly higher in Thyroxine group than in Control group (−8.59±0.68 vs−6.54±0.49, no.=8, p<0.001). Conclusions: In our hyperthyroidism model, thyroid hormone predisposed rabbits to atrial arrhythmias by shortening AMAP and AERP, which might be associated with increased ICa,Lcurrent densities in atrium.

Single layer films and a multilayer structure of SRO Silicon Rich Oxide have been prepared by LPCVD Low Pressure Chemical Vapour Deposition and characterized by FTIR, SIMS, XPS, TEM and AFM measurements. The stacked structure is composed of alternating layers of SRO with high Si content and SRO with low Si content. The layered structure is confirmed by SIMS and TEM measurements. The composition of the materials is discussed. Besides Si nanocrystals, the existence of agglomerates of silicon oxide with structure close to fused silica and the existence of oxynitrides is evidenced in the films with high Si content. © 2009 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim

The gasification technology of impinging streams has been extensively applied to chemical production and power generation. Particle residence time distribution (RTD) is an important parameter required for modeling, designing and optimization of an impinging stream gasifier. A stochastic mathematical model based on the Markov chains model is developed for the opposed multi‐burner gasifier (OMBG), which closely describes the behavior of the flow pattern and particle RTD in the gasification system. The model simulates the motion of single particle moving in the gasifier using the Markov chains. The predicted results give a reasonable fit to the experimental data. This shows that the flow process of particles in the gasifier has recirculation eddies, which have a downward flow direction near the downflow core and an upward flow direction near the wall, but no short‐circuit. Finally, the effect of particle flux rate on the RTD is predicted, and the contrast between gas and particles RTDs at a laboratory scale and in an industrial gasifier are presented.

Development of antimicrobial resistance in food animals receiving antimicrobials has been well documented among bacterial isolates, especially pathogens, but information on development of antimicrobial resistance at the microbial community level during long-term feeding of antimicrobials is lacking. The objective of this study was to examine the association between inclusion of tylosin in feed and occurrence of resistance to macrolide-lincosamide-streptogramin B (MLSB) in the entire fecal microbial communities of beef cattle over a feeding study of 168 d. A completely randomized design included 6 pens housed together in 1 barn, with each pen housing 10 to 11 steers. The control and tylosin groups each had 3 pens, with the former receiving no antimicrobial whereas the latter received both tylosin and monensin (11 and 29.9 mg/ kg of feed, respectively, DM) in feed. The abundance of genes conferring resistance to MLSB(ermgenes) and tetracyclines (tetgenes) were quantified using class-specific, real-time PCR assays. The abundances of ermand tetgenes were analyzed with pens as experimental units using the MIXED procedure of SAS. Correlations between abundance of different resistance genes were calculated using the CORR procedure of SAS. We identified 4 classes (B, F, T, and X) of ermgenes in fresh fecal samples collected at wk 2, 17, and 21 of feeding. From wk 2 to 17, the abundance of erm(T) and erm(X) increased (P< 0.05), whereas that of erm(B) and erm(F) did not. The abundance of the ermgenes did not further change from wk 17 to 21. The tet(A/C), tet(G), and tetgene variants encoding ribosomal protection proteins (including classes M, O, P, Q, S, T, and W) appeared to be co-selected by tylosin feeding. Such co-selection of multiresistance at community level by one antimicrobial drug used in animals has the important implication that future studies should examine resistance to not only the antimicrobials used in animals, but also other antimicrobials, especially those used in human medicine, to fully assess the potential risk associated with antimicrobial use in animals. Both the ermand tetgenes appeared to be disseminated among the microbial populations in all steers housed together.

Model selection and validation are critical in predicting the performance of manufacturing processes. Proper selection of variables helps minimize the model mismatch error, proper selection of models helps reduce the model estimation error, and proper validation of models helps minimize the model prediction error. In the current paper, the literature is reviewed and a rigorous procedure is proposed for selection and cross-validation (CV) of predictive regression models. Experimental data from a turning surface roughness study are used to demonstrate how to select and validate predictive regression models. In particular, different data splitting methods are compared, such as fivefold CV versus threefold CV as well as the individual data versus the average data. This paper has revealed no statistical difference between the use of fivefold CV and threefold CV, and the use of the individual and the average data in subset selection and CV of predictive regression models. Consequently, threefold instead of fivefold or tenfold CV and either individual data or average data may be used to reduce the computational cost in predictive regression modelling of experimental data based on this and other similar empirical studies.

We used immunohistochemical staining to assess protein over-expression of glial cell-derived neurotrophic factor (GDNF) and its RET receptor tyrosine kinase in patients with pancreatic cancer and benign pancreatic neoplasm, and assessed correlations with clinicopathological features and prognosis. Surgically resected pancreatic cancer patients (40/58, 68.9%) showed positive GDNF immunostaining, a significantly higher frequency than in patients with benign pancreatic tumour (3/11, 27.3%). Intrapancreatic neural invasion by cancer cells was significantly related to over-expression of GDNF. Strongly positive expression of GDNF was significantly more frequent than lesser grades of expression in patients with severe back pain before and 12 months after surgery. Expression of RET was significantly related to lymphatic invasion, survival rate after tumour resection and degree of tumour cell differentiation. We conclude that GDNF may be important in pancreatic cancer proliferation and metastasis, especially in patients with perineural invasion. Strongly positive expression of GDNF may be an indication for early intensified radiotherapy. RET expression in pancreatic cancer tissues may be a useful prognostic marker.

Background: Steroidal saponins have long attracted scientific attention, due to their structural diversity and significant biological activities. For example, total steroidal saponins extracted from the rhizome of Paris polyphyllaSm. var. yunnanensis(TSSPs) constitute an effective treatment for abnormal uterine bleeding. Objective: To determine the active constituents in TSSPs and elucidate the mechanisms that underlie their in vivopharmacologic actions on hemostasis. Methods: Steroidal saponins were purified by chromatography, and their effects upon hemostasis and platelet function were evaluated by tail bleeding time in mice and rats, aggregometry, flow cytometry and Western blotting. Results: TSSPs promoted hemostasis in vivoand dose-dependently induced rat or human platelet aggregation in vitro. Using bioassay-guided separation, four known pennogenin glycosides with a spirostanol structure were identified as the active ingredients of TSSPs. A structure–activity assay showed that the aglycone and sugar moieties of pennogenin glycosides are both essential for their aggregatory activity. Their synergistic actions on platelet aggregation were observed with pennogenin glycosides and with other known platelet agonists, suggesting that these glycosides are platelet agonists. Aggregation in response to the pennogenin glycosides involved αIIbβ3activation, was inhibited by cAMP, was dependent upon extracellular calcium, secreted ADP and thromboxane synthesis, and was mediated by phosphatidylinositol-3-kinase. Conclusion: We identified pennogenin glycosides with a spirostanol structure as the active ingredients of Paris polyphyllaSm. var. yunnanensisin promoting hemostasis in vivo. Their mode of their action on platelets suggests that they represent a new type of platelet agonist.

A process feasibility analysis on the liquid phase methanol synthesis (LPMeOHTM) process was performed in a recirculation slurry reactor (RSR). In the three‐phase RSR system, a fine catalyst is slurried in the paraffin and this catalyst slurry is continuously recirculated through the nozzle from the slurry sector to the entrained sector by a pump. The syngas is fed concurrently with the downward flow of slurry to form the methanol product. A laboratory scale mini‐pilot plant version of a recirculation slurry reactor system was successfully designed and built to carry out process engineering research, and in addition, an identical cold model was built to measure the mass transfer coefficient in the recirculation slurry reactor. The effects of operating conditions, including temperature, pressure, gas flow rate and catalyst slurry recirculation flow rate on the productivity of methanol were studied. This experimental data helps the scale‐up and commercialization of the methanol synthesis process in recirculation slurry reactors.

The possibility of generating correlated three-photon states of light (triphotons) during spontaneous parametric down-conversion of light in a cubic medium in a resonator is analysed. It is shown that the number of photons per mode of the three-photon field is proportional to the square of the resonator finesse and the number of longitudinal resonator modes satisfying the triple resonance condition.

Abstract: A failure investigation was conducted on a diesel engine gear system consisting of a driven camshaft and drive crankshaft gears that were used in a truck. The gears are made from a nitrided 42CrMo steel. Adjacent teeth fracture and plastic deformation regions appeared on the gears after a 400 h run test of the gear system. Fractography indicates that fatigue fracture is the dominant failure mechanism for the gear teeth. Although the appearance of needle-like nitrides in the nitrided layer and the narrow depth of the compound layer may decrease the fatigue strength of the camshaft gear, these do not suffice to lead to the premature fracture of the gear teeth. Geometrical analysis of the gears was performed and compared with an analysis of unfailed gears that had experienced a run test for 1800 h. The comparison reveals that the small fillet radius at the root area of the camshaft gear concentrated the stresses and is mainly responsible for fatigue fracture of the teeth. The camshaft gear is the component that initiated trouble in the gear system. The appearance of severe plastic deformation on the gear faces is caused by the fractured teeth crushing the teeth faces and being embedded in the grooves between teeth.

Trimethylacetic acid (TMAA) adsorption evolution on the rutile TiO2(110) surface from submonolayer to saturation coverages was examined at the atomic level by scanning tunneling microscopy using the same area analysis approach. Upon TMAA deprotonation, no evidence of terminal OH group formation has been found. It has been suggested that uncommon geometry associated with detached hydrogen atom takes place instead, with proton bonding to pair bridging oxygen atoms. Such a configuration is likely to be stabilized by adjacent adsorbed TMA groups and, in turn, be a factor in the formation of TMA (2 × 1) reconstruction at saturation coverage. It also shown that the surface defects do not have a major impact on TMAA adsorption.

Thin solid films of salmon deoxyribonucleic acid (DNA) have been fabricated by treatment with a surfactant and used as host for the laser dye sulforhodamine (SRh). The DNA films have an absorption peak at ∼260 nm owing to absorption by the nitrogenous aromatic bases. The SRh molecules in the DNA films have absorption and emission peaks at 578 and 602 nm, respectively. The maximum emission was obtained at ∼1 wt. % SRh in DNA, equivalent to ∼100 DNA base pairs per SRh molecule. A distributed feedback grating structure was fabricated on a SiO_2-Si substrate using interference lithography. The grating period of 437 nm was selected, corresponding to second-order emission at the amplified spontaneous emission wavelength of 650 nm. Lasing was obtained by pumping with a doubled Nd:YAG laser at 532 nm. The lasing threshold was 3 μJ, corresponding to ∼30 μJ/cm^2 or 4 kW/cm^2. The emission linewidth decreased from ∼30 nm in the amplified spontaneous emission mode to <0.4 nm (instrument limited) in the lasing mode. The slope efficiency of the lasing was ∼1.2%.

The impact tensile test was carried out on hot-rolled commercially pure titanium at temperature from 293 K to 77 K. The microstructures after fracture were examined by transmission electron microscope to determine the deformation modes. Strength and ductility increase with decreasing temperature from 293 K to 77 K. The investigation on the microstructure shows that slip cooperates with twinning in the deformation, and twinning becomes more active at lower temperature. At high strain rate titanium exhibits obvious strain hardening and twinning plays an important role in strain hardening. {1012} twin is identified in the microstructure at room temperature and three types of twins were identified at 77 K, which are {1011}, {1012}, {1121} twins.

Using accurate band structures of InAs, InSb, and two Hg_1−xCd_xTe alloys, we calculate the change in refractive index caused by the photoexcited electrons and holes. The effects of both free-carrier absorption (FCA) and one-photon absorption are considered. We find that the change in refractive index varies nonlinearly with the density of photoexcited carriers and that the generally neglected FCA contribution is significant in InAs, owing to its weak spin-orbit coupling.

AbstractObjective: To investigate associations among body composition, cardiovascular risk factors, and atherosclerosis in middle-aged and elderly men for the identification of potential pathogenic links.Research Methods and Procedures: The study included 168 white men 44 to 86 years old. Severity of aortic calcification (AC) was graded on lateral radiographs, and body fat and lean mass were measured by DXA. Information on demographic and lifestyle characteristics also was gathered.Results: A strong and independent inverse association was found between AC and peripheral lean mass (PLM), even after adjusting for age and BMI (p < 0.05). Independently of the influence of PLM, AC was directly correlated with truncal fat mass (p < 0.05). Furthermore, AC was inversely associated with tertiles of the free androgen index (p < 0.05). In a multiple regression model, age and serum cholesterol (p < 0.01) contributed directly, and truncal fat mass tended also to contribute directly (p = 0.09), whereas PLM contributed borderline inversely (p = 0.06) to the variation of AC (R = 0.635, p < 0.0001).Discussion: Severity of AC is strongly dependent on age and further modulated by an array of traditional cardiovascular risk factors. Sarcopenia and truncal fat mass are reciprocal correlates of atherosclerosis of borderline statistical significance in multivariate models. To clarify whether sarcopenia is an atherogenic risk factor or rather a parallel consequence of low-grade inflammation also promoting atherogenic trends, further longitudinal studies in larger sample sizes of men and women are needed.

This article describes progress towards producing prototype magnetoelectronic structures based on III–N semiconductor materials. We focus on the materials properties connected with the key physical phenomena underlying potential spintronic devices: producing, injecting, transporting, manipulating and detecting spin-polarized electron populations. Our experiments have shown that the maximum magnetic moment is realized for a composition of Ga0.97Cr0.03N and a substrate growth temperature of ∼1050 K. Ion channeling experiments show that ∼90% of Cr sits substitutionally on the cation site. The highest measured magnetization was 1.8μB/Cr atom (∼60% of the expected moment from band theory for ideal material) with the Curie temperature over ∼900 K. This strongly suggests a link between the CrGa impurity band and ferromagnetism and suggests that a double-exchange-like mechanism is responsible for the ferromagnetic ordering. The transport properties of spin-polarized charge carriers were modeled theoretically taking into account both the Elliott–Yafet and the D'yakonov–Perel' scattering mechanisms. We include the spin–orbit interaction in the unperturbed Hamiltonian and treat scattering by ionized impurities and phonons as a perturbation. Our numerical calculations predict two orders of magnitude longer electron spin relaxation times and an order of magnitude shorter hole spin relaxation times in GaN than in GaAs. First-principles electronic structure calculations predict that efficient spin injection can be achieved using a ferromagnetic GaN:Cr electrode in conjunction with an AlN tunnel barrier. In this structure, the electrode is found to be half-metallic up to the interface and is thus a candidate for high-efficiency magnetoelectronic devices. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Electrochemical properties of aniline in 1,2-dichloroethane are investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and in situ UV-vis spectroelectrochemistry. Aniline is an additive in gasoline, whose antiknock mechanism is extrapolated on the basis of its electrochemical properties and its reaction with hydrogen peroxide. The experimental results indicate that for aniline low parent concentration and non-protonic solvents are in favor of producing benzidine by tail-to-tail coupling of cation radicals, the nature of the reaction between aniline and hydrogen peroxide is in that the proton released from electrooxidation can interact with hydrogen peroxide. Hydrogen peroxide can reduce the resistance of the electrochemical reaction and also has an inhibiting effect on the transmission of ion from solution to the electrode surface. The results offer significant evidence and a new method for studying antiknock mechanism of aromatic amines.Electrochemical properties of aniline in 1,2-dichloroethane are investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and in situ UV-vis spectroelectrochemistry. Aniline is an additive in gasoline, whose antiknock mechanism is extrapolated on the basis of its electrochemical properties and its reaction with hydrogen peroxide. The experimental results indicate that for aniline low parent concentration and non-protonic solvents are in favor of producing benzidine by tail-to-tail coupling of cation radicals, the nature of the reaction between aniline and hydrogen peroxide is in that the proton released from electrooxidation can interact with hydrogen peroxide. Hydrogen peroxide can reduce the resistance of the electrochemical reaction and also has an inhibiting effect on the transmission of ion from solution to the electrode surface. The results offer significant evidence and a new method for studying antiknock mechanism of aromatic amines.

A series of ruthenium(II) complexes with electron-donor or electron-acceptor groups in intercalative ligands, [Ru(phen)2(o-MOP)]2+(1), [Ru(phen)2(o-MP)]2+(2), [Ru(phen)2(o-CP)]2+(3) and [Ru(phen)2(o-NP)]2+(4), have been synthesized and characterized by elementary analysis, ES-MS, 1H NMR, electronic absorption and emission spectra. The binding properties of these complexes to CT-DNA have been investigated by spectroscopy and viscosity experiments. The results showed that these complexes bind to DNA in intercalation mode and their intrinsic binding constants (Kb) are 1.1, 0.35, 0.53 and 1.7 × 105M−1, respectively. The subtle but detectable differences occurred in the DNA-binding properties of these complexes are mainly ascribed to the electron-withdrawing abilities of substituents (–OCH3< –CH3< –Cl < –NO2) on the intercalative ligands as well as the intramolecular H-bond (for substituent –OCH3) which increase the planarity area of the intercalative ligand to some extent. The density functional theory (DFT) calculations were also performed and used to further discuss the trend in the DNA-binding affinities of these complexes.A series of ruthenium(II) complexes with electron-donor or electron-acceptor groups in intercalative ligands, [Ru(phen)2(o-MOP)]2+(1), [Ru(phen)2(o-MP)]2+(2), [Ru(phen)2(o-CP)]2+(3) and [Ru(phen)2(o-NP)]2+(4), have been synthesized and characterized by elementary analysis, ES-MS, 1H NMR, electronic absorption and emission spectra. The binding properties of these complexes to CT-DNA have been investigated by spectroscopy and viscosity experiments. The results showed that these complexes bind to DNA in intercalation mode and their intrinsic binding constants (Kb) are 1.1, 0.35, 0.53 and 1.7 × 105M−1, respectively. The subtle but detectable differences occurred in the DNA-binding properties of these complexes are mainly ascribed to the electron-withdrawing abilities of substituents (–OCH3< –CH3< –Cl < –NO2) on the intercalative ligands as well as the intramolecular H-bond (for substituent –OCH3) which increase the planarity area of the intercalative ligand to some extent. The density functional theory (DFT) calculations were also performed and used to further discuss the trend in the DNA-binding affinities of these complexes.

To address the problems existing in the traditional production technique of sodium dichromate, a new green technology of producing sodium dichromate with an electrochemical synthesis method was studied. Using a self‐made electrosynthesis reactor of pure titanium and stainless steel, with a multiple‐unit metal oxides combination anode, a cathode of stainless steel, and a reinforcing combination cation exchange membrane with perfluorosulfonic and perfluorocarboxylic polymers, experiments were carried out on the direct electrochemical synthesis of sodium dichromate from sodium chromate. From the experimental results and electrochemical reaction principles, it was shown that the electrochemical synthesis reaction process of sodium dichromate may be quantitatively determined from the variation of the cell voltage measured macroscopically with reaction time. Cell voltages were experimentally measured at different initial sodium chromate concentrations in the anolyte, and the dependence of the cell voltage on reaction time was discussed. The mathematical model of the variation of cell voltage with reaction time and the change rate equation of cell voltage were established, and satisfactorily formulated the change law of cell voltage in the electrochemical synthesis process of sodium dichromate.

MoxW1−xSycomposite films were co-sputtered by the combination of MoS2and WS2targets, which were shown to have much superior tribological performance with lower and more stable friction coefficient, longer durability and higher bearing resistance than pure MoS2films in room temperature air with a relative humidity of 45–50%. Especially for the Mo0.6W0.4S1.6(40 at.% WS2) composite film, an increase in durability of more than a one order of magnitude was reached. X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to investigate the relationship between the microstructure and the tribological performance of the films. The composite films are shown to have a densified structure and accordingly improved oxidation resistance and lubrication properties. Moreover, the composite films have a lattice expansion in the cdirection, along with a reduced the friction within the films.MoxW1−xSycomposite films were co-sputtered by the combination of MoS2and WS2targets, which were shown to have much superior tribological performance with lower and more stable friction coefficient, longer durability and higher bearing resistance than pure MoS2films in room temperature air with a relative humidity of 45–50%. Especially for the Mo0.6W0.4S1.6(40 at.% WS2) composite film, an increase in durability of more than a one order of magnitude was reached. X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to investigate the relationship between the microstructure and the tribological performance of the films. The composite films are shown to have a densified structure and accordingly improved oxidation resistance and lubrication properties. Moreover, the composite films have a lattice expansion in the cdirection, along with a reduced the friction within the films.

The estrogen receptor (ESR1) gene has been implicated in the process of cognitive impairment in elderly women. In a paired case–control study, we tested whether two ESR1 gene polymorphisms (the XbaI and PvuII sites) are risk factors for cognitive impairment as measured by the six-item Orientation-Memory-Concentration test in postmenopausal Danish women. Hormone replacement therapy, age and executive cognitive ability were examined as covariates for ESR1 gene effects on cognitive impairment. The XbaI polymorphism showed a marginal effect on cognitive abilities (P0.054) when adjusted for executive cognitive ability. Using a dominant genetic model for the X allele, we found an elevated risk (executive cognitive ability adjusted P0.033) for cognitive impairment. Hormone replacement therapy also had a borderline effect on cognitive ability (P0.049) and this effect was reflected in executive cognitive ability. These data support that the ESR1 gene variants affect cognitive functioning in postmenopausal women.

Sol-gel silicate films undoped and doped with Mn and Pt are investigated by X-ray photoelectron spectroscopy and atomic-force microscopy. The effect of the annealing atmosphere on the composition and structure of doped silicate films is discussed.

We have prepared a series of achiral aminoacetonitriles, bearing tri-ring benzamide moieties and an aminocyclohexanecarboxylate residue at P2. This combination of binding elements resulted in sub-250 pM, reversible, selective, and orally bioavailable cathepsin K inhibitors. Lead compounds displayed single digit nanomolar inhibition in vitro (of rabbit osteoclast-mediated degradation of bovine bone). The best compound in this series, 39n (CRA-013783/L-006235), was orally bioavailable in rats, with a terminal half-life of over 3 h. 39n was dosed orally in ovariectomized rhesus monkeys once per day for 7 days. Collagen breakdown products were reduced by up to 76% dose-dependently. Plasma concentrations of 39n above the bone resorption IC50 after 24 h indicated a correlation between functional cellular and in vivo assays. Inhibition of collagen breakdown by cathepsin K inhibitors suggests this mechanism of action may be useful in osteoporosis and other indications involving bone resorption.

Treatment of triphenylgallium with 3,5-dimethylpyrazole, 3,5-diphenylpyrazole, or 3,5-di-tert-butylpyrazole in a 2:1 stoichiometry afforded the phenyl-bridged complexes (C6H5)2Ga(μ-Me2pz)(μ-C6H5)Ga(C6H5)2 (62%), (C6H5)2Ga(μ-Ph2pz)(μ-C6H5)Ga(C6H5)2·C7H8 (62%), and (C6H5)2Ga(μ-tBu2pz)(μ-C6H5)Ga(C6H5)2 (40%), respectively, as colorless or off-white crystalline solids. Treatment of triphenylindium with 3,5-di-tert-butylpyrazole in a 2:1 stoichiometry afforded the phenyl-bridged complex (C6H5)2In(μ-tBu2pz)(μ-C6H5)In(C6H5)2·(C6H14)0.5 (40%). The molecular structures of (C6H5)2Ga(μ-Ph2pz)(μ-C6H5)Ga(C6H5)2·C7H8, (C6H5)2Ga(μ-tBu2pz)(μ-C6H5)Ga(C6H5)2·(C6H14)0.5, and (C6H5)2In(μ-tBu2pz)(μ-C6H5)In(C6H5)2·(C6H14)0.5 consist of a 3,5-disubstituted pyrazolato ligand with a diphenylgallio or diphenylindio group bonded to each nitrogen atom. A phenyl group acts as a bridge between the two metal atoms. By contrast, treatment of triphenylgallium with 3,5-di-tert-butylpyrazole in a 1:1 stoichiometry or triphenylindium with 3,5-diphenylpyrazole or 3,5-dimethylpyrazole in 2:1 or 1:1 stoichiometry afforded the dimeric complexes [(C6H5)2Ga(μ-tBu2pz)]2 (63%), [(C6H5)2In(μ-Ph2pz)]2 (40%), and [(C6H5)2In(μ-Me2pz)]2 (92%), respectively, as colorless crystalline solids. The dimeric nature of these complexes was determined by X-ray crystallography. Treatment of 3,5-di-tert-butylpyrazole with excess trimethylgallium afforded the dimeric complex [Me2Ga(μ-tBu2pz)]2 (82%) as the major product and Me2Ga(μ-tBu2pz)(μ-OCH3)GaMe2 (2.6%) as a minor product. There was no evidence for the formation of the methyl-bridged complex Me2Ga(μ-tBu2pz)(μ-CH3)GaMe2. The kinetics of bridge-terminal phenyl exchange in (C6H5)2Ga(μ-Me2pz)(μ-C6H5)Ga(C6H5)2, (C6H5)2Ga(μ-Ph2pz)(μ-C6H5)Ga(C6H5)2·C7H8, (C6H5)2Ga(μ-tBu2pz)(μ-C6H5)Ga(C6H5)2, and (C6H5)2In(μ-tBu2pz)(μ-C6H5)In(C6H5)2·(C6H14)0.5 was determined by ¹³C NMR spectroscopy and afforded the following range of activation parameters:  ΔH^&thermod; = 6.0−8.9 kcal/mol, ΔS^&thermod; = −23.1 to −32.0 eu, and ΔG^&thermod;(298 K) = 15.5−15.8 kcal/mol. The large, negative values of ΔS^&thermod; imply ordered transition states relative to the ground state and rotation along the N−GaPh3 or N−InPh3 vector without metal−nitrogen bond cleavage. The combined results suggest that the close proximity of the metal atoms is the principal determinant of the bridging phenyl interactions and that complexes of the heavier group 13 elements with bridging hydrocarbon ligands are likely to be more accessible than the current state of literature would suggest.

A new cellular heat pipe flat solar energy collector is introduced, and the thermal performance of the new solar heater comprised by water heat pipe or acetone heat pipe is tested. The results are compared with the performance of the evacuated glass tube solar heater. It is found that: the heat loss coefficient of the cellular heat pipe flat solar heater is 54% less than that of the evacuated glass tube solar heater, while the daily average efficiency of solar absorbency is 15% higher, when the water temperature of heating is lower than 65°C. In conclusion, the thermal performance of such new solar heater is better than that of evacuated glass tube solar heater or ordinary flat solar heater, both of which are still popular in China. This new solar energy application promises to be a prosperous technology.

The growth of self‐assembled, crystalline GaN nanorods was achieved by evaporating Ga in an atmosphere of NH3at high temperature and under ambient pressure on Au‐coated Si substrates via CVD. The structure and morphology of GaN nanorods were studied by means of X‐ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). It is found that GaN nanorods are of a perfect hexagonal wurtzite structure. SEM images have shown that the typical diameter and length of GaN nanorods are ∼ 10–80 nm and ∼ 2–3 μm, respectively. A particular feature is that each nanorod was capped with a nanoparticle at its very end, by which the diameter of the nanorod was confined. The growth mechanism of GaN nanorods has been discussed with respect to the vapor‐liquid‐ solid (VLS) mechanism. This work opens up new approaches to prepare GaN nanorods and to use GaN nanorods for optoelectronic applications.

Using the catalytic system Pd(OAc)2/PPh3, coupling of 2,6-dibromopyridine (1) and pyrazoles (2) in a molar ratio of 1:2:base = 1:2.4:2.5 afforded the monosubstituted compounds 3 as the major products when KOtBu was used as the base. Without using the catalyst or using NaOtBu as the base the disubstituted compounds 4 were formed as the major products in yields up to 93%. Reactions of 1 and 2 in a molar ratio of 1:2:base = 1:1:1 selectively produced compounds 3 in yields up to 82% when KOtBu was used as the base. The complex from the reaction of 3 and Pd(OAc)2 did not undergo further reaction with 1 to form 4 in the presence of a base. The base effect and inhibition of catalytic activity for Pd(OAc)2 are discussed.

Abstract Previous work from our laboratory has shown that most of Bacillus thuringiensis strains possess the ability to produce melanin in the presence of l-tyrosine at elevated temperatures (42 °C). Furthermore, it was shown that the melanin produced by B. thuringiensis was synthesized by the action of tyrosinase, which catalyzed the conversion of l-tyrosine, via l-DOPA, to melanin. In this study, the tyrosinase-encoding gene (mel) from B. thuringiensis 4D11 was cloned using PCR techniques and expressed in Escherichia coli DH5 a. A DNA fragment with 1179 bp which contained the intact mel gene in the recombinant plasmid pGEM1179 imparted the ability to synthesize melanin to the E. coli recipient strain. The nucleotide sequence of this DNA fragment revealed an open reading frame of 744 bp, encoding a protein of 248 amino acids. The novel mel gene from B.thuringiensis expressed in E. coli DH5 a conferred UV protection on the recipient strain.

Lewis acid assisted ring-closing olefin metathesis (RCM) of chiral diallylamines, using the second generation RCM ruthenium-based catalyst, leads to enantiopure pyrrolidine derivatives in 79−93% yields under very mild conditions. The scope of the olefin metathesis has been expanded.

Fabrication of p-type ZnO has proven difficult and usually inconsistent despite numerous worldwide efforts. In this theoretical study we explored the problem of p-type ZnO formation using both DFT and thermochemistry calculations. Our DFT models predicted that Zn3P2 is a good dopant because it can lead to a shallow acceptor level at 0 K. Additional thermochemistry calculations demonstrated that this shallow acceptor can be further stabilized in a real fabrication process. Our models explain well the observed trends for both n- and p-type phosphorus-doped ZnO and especially the observed inconsistent behaviors of P2O5 dopant. A new strategy of fabricating p-type ZnO was proposed thereafter. This research may also help to address the problem of dopant selection in the fabrication of other wide-gap semiconductors.

Domino [4+2]/[2+2] cycloaddition of 2-isopropenyl-2-oxazoline 2 to 1-alkynyl Fischer carbene complexes (CO)5M&dbd;C(OEt)C&tbd1;CPh 1 (a, M = Cr; b, W) in a 1:2 molar ratio afforded unusually stable biscarbene complexes 3a and 3b containing a novel four-, five-, and six-membered tricyclic core in 99.6% and 45.2% yields, respectively. Chain-opening β-aminoalkenyl monocarbene complex 4b and β-amidoalkenyl monocarbene complex 5b of tungsten were also isolated from the cycloaddition upon treatment of the reaction mixture of 1b and 2 on silica gel. Partial and full oxidation of 3a,b with pyridine N-oxide underwent efficient chemoselective stepwise demetalation to afford the corresponding monocarbene complexes 6a,b and organic diester 7, respectively, under mild conditions. The X-ray crystallographic study revealed the presence of a four-, five-, and six-membered tricyclic core in compounds 3, 6, and 7, and the methyl and oxazolindinyl groups derived from oxazoline 2 are positioned syn with respect to the azabicyclo[4.2.0]octadiene bicyclic moiety, which is oriented in the opposite direction. X-ray crystal structural data are reported for the bis- and monocarbene complexes 3a, 5b, and 6b as well as for diester 7.

No Heading The magnetoresistance ?xx in a quasi-two-dimensional electron system over liquid helium has been measured for magnetic fields up to 2 T in the temperature range 0.5 – 1.7 K. It has been shown that the behavior of the value of ?xx as a function of a magnetic field B in the temperature region 1.2 – 1.7 K and at temperature T < 0.9 K is different. At high temperatures the negative magnetoresistance is observed due to weak localization of carriers, at T < 0.9 K the ?xx increases monotonically under increasing B. It is supposed that such a difference in the behavior of the ?xx is connected with the different character of the electron scattering: elastic at high temperatures, in the region of gas scattering, and inelastic at low temperatures. The last effect gives an additional evidence either for spatial ordering of electrons or for the formation of electron polarons in quasi-two- dimensional channels.

Estrogen deficiency has been implicated as a risk factor for cognitive impairment in elderly women, yet the role of hormone therapy (HT) to prevent this event remains controversial. The aim of this study was to investigate the impact of administration of HT for 2 to 3 years in the early postmenopausal years on the risk of cognitive impairment 5 to 15 years later.

No Heading The transverse magnetoresistive effects in a nondegenerate quasi-one-dimensional (Q1D) electron system over superfluid helium have been investigated experimentally. The longitudinal magnetoresistance ?xx have been measured in magnetic fields B up to 2.5 T in the temperature range 0.48 – 2 K. The width of conducting channels was 90 nm and 35 µm, the mean electron density varied from ~ 109 m-2 to 1.5 × 1012 m-2. It has been shown that the value of ?xx practically does not depend on B at low B and ?xx ~ B in the quantum regime. The effective mobility of electrons in narrow channels increases under decreasing temperature and is determined by electron scattering by gas atoms, ripplons, and non-uniformities of the substrate. The mobility of electrons in wide channels increases with decreasing temperature and, below some temperature Tm, decreases. The negative magnetoresistance has been observed in the gas- and ripplon-scattering region. This effect has been explained by weak localization of carriers caused by the interaction of electrons with gas atoms in vapor at high temperatures and with ripplons or with non-uniformities of the substrate at low temperatures.

To compare bone mineral density (BMD) and bone turnover changes after therapy withdrawal in postmenopausal women treated with alendronate or estrogen-progestin.

Objective: To investigate how body fat mass, an established source of endogenous estrogen after menopause, influences cognitive impairment in elderly women. Research Methods and Procedures: Study participants were 5607 generally healthy postmenopausal women with mean age of 63.8 years at baseline followed for an average of 7.3 years. Cognitive function assessed at follow‐up using the short Blessed test was related to baseline body weight, the yearly change in weight, and follow‐up measures of body fat depots assessed by DXA. Cognitive function was also related to various surrogates of lifetime estrogen exposure. Results: Women with the worst cognitive performance (score ≥ 9) at follow‐up were the ones who lost the most body weight and revealed the lowest central fat mass (CFM). The association of weight loss with worse cognitive performance was apparent across all age groups except for those more than 80 years old. In the multivariate logistic model, the risk of cognitive impairment was 18% lower in women in the second quartile of CFM (p= 0.14), 32% lower in the third (p= 0.01), and 48% lower in the fourth (p< 0.001) compared with those in the first quartile. CFM showed significant correlation with the simultaneously measured serum estradiol (r= 0.25; p< 0.001). Cognitive score showed an inverse linear relationship with the duration of reproductive period and bone mineral density assessed at follow‐up. Discussion: These findings argue for a protective association of body fat mass with cognitive impairment in elderly women. This association seems to involve a more prominent exposure to endogenous estrogens.

Oral administration of calcitonin could improve compliance to long‐term treatment. Efficacy and safety of a novel oral formulation was assessed on 277 postmenopausal women. The results show (1) effective enteral absorption, (2) marked inhibition of bone resorption with minimal alteration of formation, and (3) reproducibility of responses over 3 months.

Glass beads were modified with vinyl triethoxyl silane (VTES) followed by in situ copolymerization with styrene (St) and by direct modification with St via in situ polymerization. It was seen that the presence of glass beads did not inhibit the polymerization of St, and FT-IR spectra confirmed that the polystyrene (PS) molecules were grafted on the surfaces of glass beads. When the modified glass beads were filled in a poly(phenylene oxide) (PPO) matrix, the PS segments on the surfaces of glass beads clearly improved compatibility and enhanced interfacial adhesion between the PPO matrix and glass beads, which was responsible for the slightly increased glass transition temperature of the PPO component. Surface modifications, especially by in situ copolymerization of VTES and St, increased significantly notch impact strengths and marginal stiffness and tensile strengths of PPO/glass bead composites.

Abstract: We have developed a process to grow epitaxial SrTiO3 (STO) on Si. This STO/Si substrate can then be used as a pseudo substrate for the further deposition of many other oxides that are closely lattice matched to STO. The STO is grown by molecular-beam epitaxy (MBE) with a subsequent oxide layer deposited either by MBE or sol-gel deposition. The pseudo substrate has been used to demonstrate ferroelectric devices and piezoelectric devices. Ferroelectric capacitors using epitaxial BaTiO3 (BTO) show a memory window of 0.5 V; however, the retention time for these devices is short because of the depolarization field caused by the silicon-oxide interface layer used to improve the band alignment of the BTO/Si interface. Surface acoustic wave (SAW) resonators using epitaxial Pb(Zr,Ti)O3 show excellent response with a coupling coefficient of 4.6% and a velocity of 2,844 m/s.