Search

Insect chitin deacetylases (CDAs) are carbohydrate esterases that catalyze N‐deacetylation of chitin to generate chitosan, a process essential for chitin organization and compactness during the formation of extracellular chitinous structure. Here we identified two CDA2 splice variants (LdCDA2a and LdCDA2b) in Leptinotarsa decemlineata. Both splices were abundantly expressed in larval foregut, rectum, and epidermis; their levels peaked immediately before ecdysis within each instar. In vivo results revealed that the two isoforms transcriptionally responded, positively and negatively respectively, to 20‐hydroxyecdysone and juvenile hormone signaling pathways. RNA interference (RNAi)‐aided knockdown of the two LdCDA2 variants (hereafter LdCDA2) or LdCDA2b, rather than LdCDA2a, resulted in three negative effects. First, foliage consumption was significantly reduced, larval developing period was lengthened, and larval growth was retarded. Second, chitin contents were reduced, whereas glucose, trehalose, and glycogen contents were increased in the LdCDA2 and LdCDA2b RNAi larvae. Third, approximately 20% of LdCDA2 and LdCDA2b RNAi larvae were trapped within the exuviae and finally died. About 60% of the abnormal pupae died as pharate adults. Around 20% of the RNAi pupae emerged as deformed adults, with small size and wrinkled wings. These adults eventually died within 1 week after molting. Our results reveal that knockdown of CDA2 affects chitin accumulation. Consequently, LdCDA2 may be a potential target for control of L. decemlineata larvae. [ABSTRACT FROM AUTHOR]

Hydroponic-grown seedlings of aspen (Populus tremuloides Michx.) were used to investigate how low root temperatures (5°C) affect stomatal conductance and water relations. An isohydric manner of the stomatal behaviour was found with the seedlings when their roots were subjected to the low temperature. Stomatal conductance rapidly and dramatically reduced in response to the low root temperature, while the xylem water potential did not significantly alter. Under the low root temperature, pH value of the xylem sap increased from 6.15 to 6.72 within the initial 4 h, while abscisic acid (ABA) concentration increased by the eighth hour of treatment. K+ concentration of the xylem sap significantly decreased within the 8th h and then reversed by the 24th h. The ion change was accompanied by a decrease and then an increase in the electrical conductivity, and an increase and then a decrease in the osmotic potential. The tempo of physiological responses to the low root temperature suggests that the rapid pH change of the xylem sap was the initial factor which triggered stomatal closure in low temperature-treated seedlings, and that the role of the more slowly accumulating ABA was likely to reinforce the stomatal closure. Xylem sap from the seedlings subjected low root temperature affected stomatal aperture on leaf discs when they were floated on the sap solution. The stomatal aperture correlated (P = 0.006) with the changed pattern of [K+] in the sap while the range of pH or ABA found in the xylem sap did not influence stomatal aperture of leaf discs in solution. The effect of xylem sap on stomatal aperture on leaf discs was different from on stomatal conductance in the intact seedlings. Comparison was made with previous study with the soil-grown seedlings. [ABSTRACT FROM AUTHOR]

Increase of peroxisome proliferator-activated receptor δ (PPARδ) expression by digoxin in the heart of diabetic rats has been documented. The present study investigated the mediation of PPARδ in lipid metabolism improved by digoxin in the heart of diabetic rats and in the hyperglycemia-treated cardiomyocytes using the primary cultured cardiomyocytes from neonatal rat. The lipid deposition within the heart section was assessed in diabetic rats by oil red O staining. The fatty acid oxidation genes in cardiomyocytes were also examined. Inhibitor of calcium ions and siRNA-PPARδ were employed to investigate the potential mechanisms. After a 20-day digoxin treatment, the PPARδ expression was elevated in hearts of diabetic rats while the cardiac lipid deposition was reduced. In neonatal cardiomyocytes, digoxin also caused an increase in expressions of PPARδ and fatty acid oxidation genes. But both actions of digoxin were blocked by BAPTA-AM to chelate calcium ions and by siRNA-PPARδ in cardiomyocytes. The obtained results show that increase of PPARδ by digoxin is related to regulation of fatty acid oxidation genes in cardiac cells mediated by calcium-triggered signals. [ABSTRACT FROM AUTHOR]

A wire-grid terahertz polarizer fabricated on quartz substrate working in broadband is demonstrated. The transmission spectra of the fabricated wire-grid polarizer are characterized by terahertz time domain spectroscopy, showing the good performance of this polarizer in the terahertz frequency range up to 3.5 THz. The transmission of the peak in the time domain is 80% when the incident terahertz wave polarization is perpendicular to the wire-grid. The transmission of the peak is lower than 10% when the incident polarization is parallel to the wire-grid. The polarization factor ranges from 0.92-0.99 with the mean value of 0.97 in the frequency range from 0.1 to 3.5 THz, which is better than that of the free-standing wire-grid polarizer. [ABSTRACT FROM AUTHOR]

Large-area split ring resonator (SRR) array was fabricated by femtosecond laser micro-lens array lithography at a fast speed. Transmission spectra of the SRR arrays at different incident terahertz wave polarization states were characterized by terahertz time domain spectroscopy. A polarization-dependent transmission property of the SRR array was observed. Polarization-dependent loss (PDL) spectrum was characterized to investigate the polarization properties of the terahertz metamaterials. The PDL characterization can eliminate the substrate effect and provide a flexible platform to study the characteristics of free-standing terahertz metamaterials. [ABSTRACT FROM AUTHOR]

Abstract: Bismuth telluride (Bi2Te3) bulk material was prepared by a powder hot-extrusion technique. The microstructure, texture evolution, and deformation-induced lattice defects, as well as the effect of heat treatment on its microstructure and thermoelectric properties were investigated. As-extruded Bi2Te3 compound was found to be characterized by a dynamically and statically recrystallized microstructure with fine-equiaxed grains and low dislocation density. The majority of boundaries in the extruded specimens were large-angle boundaries with average misorientation angles of more than 30°. There was no significant change in dislocation configuration, even after heat treatment at a temperature higher than the extrusion temperature. Moreover, the Seebeck coefficient and electrical resistivity of the extruded specimens could not be improved by annealing. Microstructural examinations indicated the existence of a deformation-induced stacking disorder with local atomic shift, which we term “phase disorder,” on the basal plane in the extruded Bi2Te3 compound. The presence of this structural defect may be one of the main reasons for the slightly lower values of thermoelectric properties for the hot-extruded Bi2Te3 compound, compared with a unidirectionally solidified specimen. [Copyright &y& Elsevier]

In this study, a nanofiber mesh made by co-electrospinning medical grade poly(ε-caprolactone) and collagen (mPCL/Col) was fabricated and studied. Its mechanical properties and characteristics were analyzed and compared to mPCL meshes. mPCL/Col meshes showed a reduction in strength but an increase in ductility when compared to PCL meshes. In vitro assays revealed that mPCL/Col supported the attachment and proliferation of smooth muscle cells on both sides of the mesh. In vivo studies in the corpus cavernosa of rabbits revealed that the mPCL/Col scaffold used in conjunction with autologous smooth muscle cells resulted in better integration with host tissue when compared to cell free scaffolds. On a cellular level preseeded scaffolds showed a minimized foreign body reaction. [ABSTRACT FROM AUTHOR]

At a concentration of 0.4 μg purified pokeweed antiviral proteiin (PAP)/ml, the formation of local lesions on tobacco leaves caused by tobacco mosaic virus infection was completely inhibited and at 25 ng PAP/ ml. 68% inhibition was still obtained. PAP protected plants from infection by viruses from seven virus groups—five RNA viruses: tobacco mosaic virus, cucumber mosaic virus, alfalfa mosaic virus, potato virus X and potato virus Y; and two DNA viruses: African cassava mosaic virus (ssDNA)and cauliflower mosaic virus (dsDNA). Virus infection was probably blocked by PAP at a very early stage. PAP infiltrated into the intercellular spaces through the lower surfaces of leaves inhibited infection by virus inoculated on the upper lear surface, and partially prevented PVY transmission by aphids. However, PAP did not show any activity against two bacterial and six fungal pathogens. [ABSTRACT FROM AUTHOR]

Large-area asymmetric split ring resonator (ASRR) arrays are fabricated by femtosecond laser microlens array lithography. The double square ASRR consists of two gaps at the outer edge. The resonance properties of this ASRR under structural symmetry breaking conditions are investigated in the terahertz region by changing gap size at one side. The resonance of the ASRR shows blueshift from 0.85 to 0.98 THz when the one gap size increases from 2 to 14 μm. Numerical simulations reveal that the electric field enhancement at the fixed gap increases from 152 to 206 times as the degree of asymmetry increases. [ABSTRACT FROM AUTHOR]

Quantifiably monitoring sweat rate and volume is important to assess the stress level of individuals and/or prevent dehydration, but despite intense research, a convenient, continuous, and low-cost method to monitor sweat rate and total sweat volume loss remains an un-met need. We present here an ultra-simple wearable sensor capable of measuring sweat rate and volume accurately. The device continuously monitors sweat rate by wicking the produced sweat into hydrogels that measurably swell in their physical geometry. The device has been designed as a simple to fabricate, low-cost, disposable patch. This patch exhibits stable and predictable operation over the maximum variable chemistry expected for sweat (pH 4–9 and salinity 0–100 mM NaCl). Preliminary in vivo testing of the patch has been achieved during aerobic exercise, and the sweat rates measured via the patch accurately follow actual sweat rates. [ABSTRACT FROM AUTHOR]

The article examines the association between susceptible gene polymorphisms and age, sex and body mass index in gallstone disease. The study showed that the serum total cholesterol and both low- and high-density lipoprotein cholesterol levels were significantly lower in subjects with gallstones. Based on the results, the researchers concluded that age, sex and body mass index were not associated with carriers of ABCG5 604Q or ABCG8 D19H polymorphisms.

We report the effects of oxygen content on the transport properties of La0.7Ca0.3MnO3-δ thin films grown epitaxially on LaAlO3 (001) substrates by RF magnetron sputtering. The as-deposited thin films were annealed and treated by oxygen plasma to improve the oxygen content. We observe that the La0.7Ca0.3MnO3-δ films annealed at 850°C is highly oriented growth on (001) LAO substrate. However, the XRD patterns of the samples annealed at lower than 850°C show no distinct diffraction peaks. This evidence indicates that the samples annealed at lower than 850°C are still amorphous or nanocrystalline. The La0.7Ca0.3MnO3-δ films without oxygen plasma do not suffer insulator to metal transition at the temperature range from 213 to 293 K. But, at the same temperature range, for the 650°C, 750°C, and 850°C annealed samples with oxygen plasma treatment show an insulator to metal transition at 239 K, 239 K, and 257 K, respectively. Moreover, compared to without oxygen plasma treatment, the resistivity of the sample with oxygen plasma treatment is dramatically decreased. These results imply that the insulator to metal transition is strongly determined by the ratio of Mn4+/Mn3+ and the oxygen content of the films. The increases of the ratio of Mn4+/Mn3+ and the oxygen content lead to a higher insulator to metal transition temperature. [ABSTRACT FROM AUTHOR]

In this study, reduced-graphene oxide (GO) circuits were directly patterned on glass using an industrially available excimer laser system. A threshold of laser energy density was observed, which provided a clear differentiation on whether the GO was reduced. A sharp drop of resistance by a factor of 104 was measured as the laser energy density increased from 65 to 75 mJ/cm2. The highest conductivity measured was ∼1.33 × 104 S/m, which is among the best reported in the literature for any laser reduction method. Raman analysis of the excimer laser-reduced GO film revealed the formation of a prominent 2D peak at 2700 cm-1. The relative signal strength between the Raman D and G peaks suggests that the amount of structural disorder in the reduced GO is insignificant. The reduced GO displays a transmittance greater than 80% across the entire range from 450 to 800 nm. The outstanding electrical, optical, and morphological properties have enabled graphene to display promising applications, and this nano-processing method makes graphene even more attractive when used as a transparent electrode for touch screens and in many more applications. [ABSTRACT FROM AUTHOR]

The split ratio, i.e., the ratio of rotor outer diameter to stator outer diameter, is one of the most vital design parameters for permanent-magnet (PM) machines due to its significant impact on the machine torque or power density. However, it has been optimized analytically in the existing papers with due account only for the stator copper loss, which is reasonable for low-to-medium speed PM machines. For high-speed PM machines (HSPMMs), the negligence of stator iron loss and the mechanical stress on the rotor will lead to a deviation of optimal split ratio and actual torque capability. In this paper, the optimal split ratio of HSPMM is investigated analytically with the consideration of stator iron loss as well as the mechanical stress on the rotor. The influence of air-gap length and rotor pole pairs on the optimal split ratio is elaborated. Both the analytical and finite-element analysis reveal that the optimal split ratio for HSPMM will be significantly reduced, when stator iron loss and mechanical constraints are taken into account. [ABSTRACT FROM AUTHOR]

Magnetic Fe3O4/graphene oxide nanocomposites were synthesised by a simple hydrothermal method. The morphology and composition of the magnetic Fe3O4/graphene oxide nanocomposites were optimised and characterised by ultraviolet-visible spectra, Fourier transform infrared spectra, zeta-potential and scanning electron microscope. It was found that Fe3O4 nanoparticles with the mean diameter of about 15-30 nm were firmly decorated on the surfaces of graphene oxide. The Fe3O4/graphene oxide nanocomposites presented an excellent colloidal stability over a wide range of pH. Furthermore, the Fe3O4/graphene oxide nanocomposites could be quickly separated from an aqueous solution with the application of an external magnetic field. [ABSTRACT FROM AUTHOR]

Thrombomodulin is an endothelial glycoprotein that decreases thrombin activity and activates protein C. A recent study has shown that G-33A promoter mutation of the thrombomodulin gene occurs particularly in Asians. In this study, we analyzed the distribution of G-33A mutation in the promoter region of the thrombomodulin gene in the Chinese population and determined whether the mutation might be a risk for coronary artery disease (CAD). In addition, the influence of this mutation on plasma soluble thrombomodulin levels in patients with CAD was also examined. We studied 320 consecutive patients (mean age 63 years; 73% men) with CAD and 200 age- and sex-matched control subjects. Screening for thrombomodulin G-33A promoter mutation was conducted using polymerase chain reaction, single-strand conformation polymorphism, and direct deoxyribonucleic acid sequencing. The frequency of the G-33A mutation (GA+AA genotypes) was significantly higher in the CAD group (23.8% vs 15.5%, odds ratio [OR] 1.70, p = 0.031). Multiple logistic regression analysis showed that the mutation was an independent risk factor (OR 1.81, p = 0.016) for CAD, as was hypertension (OR 1.44, p = 0.040), diabetes mellitus (OR 2.50, p <0.001), and smoking (OR 2.15, p <0.001). In CAD patients with GG genotype, the soluble thrombomodulin level increased with the extent of CAD (36 +/- 15 vs 47 +/- 18 vs 55 +/- 36 ng/ml in 1-, 2-, or 3-vessel CAD, p <0.001). However, in CAD patients with G-33A mutation, there was no difference between the levels of soluble thrombomodulin (39 +/- 17 vs 37 +/- 15 vs 42 +/- 18 ng/ml, p = NS) in 1-, 2-, or 3-vessel CAD. Our observations suggest that there is a significant association of the G-33A mutation in thrombomodulin gene with CAD, and this mutation may influence the soluble thrombomodulin levels in patients with CAD. [ABSTRACT FROM AUTHOR]