Controlled growth of well-aligned GaS nanohornlike structures and their field emission properties

Here, we report the synthesis of vertically aligned gallium sulfide (GaS) nanohorn arrays using simple vapor-liquid-solid (VLS) method. The morphologies of GaS nano and microstructures are tuned by controlling the temperature and position of the substrate with respect to the source material. A plausible mechanism for the controlled growth has been proposed. It is important to note that the turn-on field value of GaS nanohorns array is found to be the low turn-on field 4.2 V/μm having current density of 0.1 μA/cm(2). The striking feature of the field emission behavior of the GaS nanohorn arrays is that the average emission current remains nearly constant over long time without any degradation.     

Electrodeposited zinc oxide thin films: Nucleation and growth mechanism

The nucleation and growth mechanism of the electrodeposited zinc oxide thin films on fluorine-doped tin oxide (FTO) coated (10–20 Ω/cm²) glass substrates from acetate solution, without and with ex situ oxygen bubbling, has been studied by cyclic voltammetry (CV), chronoamperometry (CA) and scanning electron microscopy (SEM) techniques. Ethylene diamine tetra acetic acid (EDTA) was used as a complexing agent. The cyclic voltammograms exhibit crossover, a characteristic of nucleation process on FTO-coated conducting glass substrates for all the baths bubbled with oxygen. The current transients were analyzed by fitting chronoamperometric data into the Scharifker–Hills nucleation model. The plausible nucleation and growth mechanism is proposed. For mother bath and lower oxygen bubbling time, the nucleation and growth mechanism follows 3D progressive nucleation and growth, which became instantaneous in case of baths for higher oxygen bubbling time. The SEM study showed that the films become compact when the oxygen bubbling time was increased. The thin films were further characterized by X-ray diffraction technique for structural studies and the ZnO film formation was confirmed. With the increase in oxygen bubbling time, the shift in band gap energies from 3.2 to 3.3 eV is observed.     

Circular Polarization in Defected Hexagonal Shaped Microstrip Antenna

A novel circular polarization (CP) design of a single-feed Hexagonal shaped microstrip antenna for enhanced antenna parameters is presented. The CP design is obtained by placing three isosceles triangular defects at proper locations in the hexagonal radiating patch as well as in the square ground plane. By adjusting one of the side lengths of the triangular defect, slightly longer or shorter than that of the others, two orthogonal near degenerate resonant modes for CP radiation are excited. Moreover, the 3 dB axial ratio bandwidth is surrounded by the 10 dB impedance bandwidth, to ensure that the antenna radiates CP waves in its impedance band. The antenna gain of the proposed antenna has increased by 5.34 dB (7.93 vs. 2.59 dB), as compared to the hexagonal microstrip antenna with triangular truncations in patch but without triangular defects in the ground plane having same substrate material, height and same radiating patch size and shape. Prototype antenna is fabricated for experimental evaluation. Simulated and measured results are in good agreement with each other.     

Structural, morphological, optical and photoluminescent properties of spray-deposited ZnSe thin film

Zn Se thin films are successfully deposited by spray pyrolysis deposition technique.Deposited thin films are characterized by X-ray diffraction study,and it reveals that spray-deposited Zn Se thin films are polycrystalline with hexagonal crystal structure.Surface morphology is carried out by scanning electron microscopy.It shows cotton-like morphology,and optical properties,such as absorbance,transmittance,reflectance,band gap,refractive index,extinction coefficient are studied.Photoluminescence shows strong emission at 497 nm.Also,spraydeposited Zn Se thin films are hydrophilic in nature,which is shown by contact angle meter.     

Optical properties of electrochemically synthesized polypyrrole thin films:the electrolyte effect

Polypyrrole thin films are prepared by the potentiostatic mode of electrodeposition at ＋0.7 V versus a saturated calomel electrode （SCE）. The polypyrrole films are prepared in the presence of different electrolytes such as： p-toluene sulphonic acid （PTS）, oxalic acid and H2SO4. The prepared films are characterized by UV- vis absorption spectroscopy and normal reflectance measurements. The electrochemically synthesized films are semiconductor in nature. The band gap energy ofpolypyrrole thin films is found to be 1.95, 1.92 and 1.79 eV for H2 SO4, oxalic acid and p-toluene sulphonic acid, respectively. The normal reflectance spectroscopy of polypyrrole films shows that the maximum reflectance is in the presence of p-toluene sulphonic acid; this is may be due to a more distinct microstructure than the others. The optical constants such as the extinction coefficient, refractive index, optical conductivity, etc. are calculated and studied with various electrolytes.     

计算延时线的最大工作频率

<正>1计算最大输入频率对于一个固定延迟的延时线电路,在计算所允许的最大输入信号频率时需要考虑的关键参数是输入信号的最小脉冲宽度。对于占空比为50%的周期性信号,脉冲宽度为周期的一半。但有些周期性的低频输入信号的占空比低于50%。这种情况下,输入信号瞬变之间的最     

Some Transition Metal Salts of 4,6‐Dinitrobenzofuroxan: Synthesis,Characterization and Evaluation of Their Properties

Chromium, Iron and Copper salts of 4,6‐dinitrobenzofuroxan have been prepared by reacting sodium salt of 4,6‐dinitrobenzofuroxan with chromium nitrate nonahydrate, ferric nitrate nonahydrate and cupric nitrate trihydrate, respectively. The compounds have been characterized by elemental analysis, spectral data (IR and NMR) and metal content. Some properties including thermal and explosive behaviour of these compounds have been investigated and reported. Further, these molecules have also been investigated in composite propellants as burn‐rate modifiers. The preliminary data suggest that iron salt of 4,6‐dinitrobenzofuroxan is better than ferric oxide, generally used as a burn‐rate modifier for hydroxy‐terminated polybutadiene (HTPB) based composite propellants.     

N-benzyl-N-ethylaniline; an alternative synthetic approach

An alternative one-pot synthesis of N-benzyl-N-ethylaniline, an important dyestuff intermediate, has been achieved by reductive alkylation of easily available aniline as starting material. The reaction has been extended to the preparation of other substituted N-benzyl-N-ethylanilines. New insights into the mechanism of the reactions have been obtained. A more economical two-stage process involving reductive ethylation of N-benzylaniline has been examined.     

Effect of enterotoxigenic Escherichia coli vaccine on innate immune function of bovine mammary gland infused with lipopolysaccharide

The effects of using an enterotoxigenic Escherichia coli vaccine on innate immune responses following intramammary infusion of lipopolysaccharide (LPS) were investigated in midlactation Holstein-Friesian cows. Seven out of 14 cows were inoculated with E. coli vaccine. Three weeks later, 100μg of LPS dissolved in 10mL of saline was infused into 1 quarter of all cows. Milk was collected every hour from infusion to 12h after infusion, and twice daily (at 0900 and 1600h) for 4d. Blood samples were collected 0, 4, 8, 24, 48, 72, and 96h after infusion. Rectal temperatures and milk yields were measured. The somatic cell count (SCC), lingual antimicrobial peptide concentration, lactoperoxidase (LPO) activity, and lactoferrin (LF) concentration in milk, and haptoglobin concentration in serum were determined. The mean rectal temperature in vaccinated cows was higher than in control cows at 10h. The mean milk yield was decreased significantly in the infused quarter of control cows at 24h compared with pretreatment, but not in vaccinated cows. The mean SCC in milk from vaccinated cows at 12 and 55h was significantly lower than that of control cows. The lingual antimicrobial peptide and LF concentrations were significantly lower at 8h and 55h, respectively, in vaccinated cows than in control cows. The mean antibody titer in the serum against the vaccine at the time of LPS infusion into vaccinated cows was significantly higher than in control cows. These antibody titers were positively correlated with the peak concentrations of LPO and LF in milk following challenge; therefore, cows with a high antibody titer were accompanied by high LPO activity and LF concentration in milk. These results suggest that vaccination suppresses the innate immune reaction after intramammary LPS infusion; however, the elevated antibody titer was unlikely to be responsible for the modification of the innate immune reaction.     

Solar light assisted photocatalysis of water using a zinc oxide semiconductor

The photocatalytic decomposition of an eco-persistent AO7 dye with sunlight in an oxygenated aqueous suspension has been studied under a nano-crystalline hexagonal ZnO photocatalyst.The effect of substrate temperature on the structural,morphological and photoactive properties has been investigated.The degradation of the A07 dye is achieved using a photoelectrochemical reactor module equipped with ZnO synthesized electrodes. Kinetic parameters have been investigated in terms of a first order rate equation.The rate constant for this heterogeneous photocatalysis was evaluated as a function of the initial concentration of original species.A substantial reduction in A07 dye is achieved as analyzed from COD and TOC studies.The mechanism for the degradation could be explained on the basis of the Langmuir-Hinshelwood mechanism.