Kinetics of electroless Ni-Cu-P deposits on silicon in a basic hypophosphite-type bath

Eleetroless Ni-Cu-P deposits were deposited on the Si substrate in a basic hypophosphite-type plating bath.The effects ofpH value and the metal source composition, Ni and Cu, in the plating bath on the kinetics of the Ni-Cu-P deposition were studied.The electroless Ni-Cu-P deposits were characterized by a scanning electron microscope, a transmission electron microscope, an en-ergy dispersive X-ray spectroscope, and an X-ray diffractometer.The results showed that the pH value of the plating bath had no ob- vious effect on the morphology and composition of electroless Ni-Cu-P deposits.However, the composition of the metal source, Ni and Cu, in the plating bath had great effect on the kinetics of electroless Ni-Cu-P deposition.     

Optimization of α‐amylase production in solid substrate fermentation

Response surface methodology (RSM) was used to optimize the medium components of α‐amylase production using solid substrate fermentation (SSF). Hazelnut cake (HC), peptone, yeast extract (YE), and (NH₄)₂SO₄ were selected as independent variables for optimization. Central composite design (CCD) was used in design experiments and analysis results. This procedure limited the number of actual experiments performed while allowing possible interactions between the independent variables. By using CCD, 30 experiments were performed for determining the interaction of independent variables and optimization of fermentation medium. The P‐value of the coefficient of linear effect of (NH₄)₂SO₄ concentrations, which was obtained as 0.0001 has shown that this parameter has the greatest effect on the production of α‐amylase. Model F‐value (5.62) implies that the model is significant. The highest α‐amylase activity (4895 IU) was measured when the HC, peptone, YE, and (NH₄)₂SO₄ concentrations in the medium were 22.62, 5.20, 1.62, and 6.81 g L^?1, respectively.     

Probe microanalysis investigation and electroreflectance spectroscopy of Hg1−xCdxTe PLD films on silicon patterned substrates

Hg_1−xCd_xTe films were prepared on Si-patterned substrates by the pulse laser deposition technique from a Hg_1−xCd_xTe target (x≈0.2). The effects of different substrate temperatures, ranging from 293 to 543 K, different laser shots number in the range of 10–380, and the morphological type of the patterned substrate on the x-composition of films were studied by electron probe microanalysis (EPMA) and electroreflectance (ER) spectroscopy. The correlation between a film composition measured by EPMA and one determined from ER spectra data was observed.     

Development of numerically controlled local wet etching

Numerically controlled local wet etching (NC-LWE) has been developed as a novel noncontact subaperture deterministic figuring method for fabricating ultraprecision optics or for finishing functional materials. In this method, a localized wet etching area is formed using a combined nozzle that is constructed by coaxially arranging the supply part and the suction part of the etchant. The removal volume anywhere on the workpiece surface is determined by the convolution of the removal function and the dwelling time distribution of the nozzle. The machining properties of this method are insensitive to external disturbances, such as vibration or thermal deformation, because the removal process is performed under a noncontact condition.I applied NC-LWE to finish a 6 in photomask substrate made of synthesized quartz glass having size of 6 in, and improved the flatness of the substrate from 260 to 69 nm by only one NC-LWE correcting process.     

A study of the dissipative properties of homogeneous materials deposited as coatings. Part 1. Method for the determination of the amplitude dependence of the true vibration decrement of the coating material

A method is proposed for the determination of the amplitude dependence of the true vibration decrement of homogeneous materials deposited as coatings on a substrate of rectangular cross section. The method is based on the self-consistent calculation of energy loss factors for the substrate and coating materials using experimental amplitude dependences of vibration decrement for coated substrate, obtained under the conditions of cantilever specimens of rectangular cross section. The applicability of the method is illustrated by the determination of values of the true vibration decrement of Co-20 wt.% Fe alloy deposited as a coating on VT1-0 titanium alloy. __________ Translated from Problemy Prochnosti, No. 6, pp. 134–143, November–December, 2007.     

Hydrogenation of HgCdTe epilayers on Si substrates using glow discharge plasma

Preliminary results of a study of the hydrogenation of HgCdTe epilayers grown by molecular beam epitaxy on Si substrates using a glow-discharge plasma are presented. The aim of the program is to employ H to passivate the detrimental opto-electronic effects of threading dislocations present in the HgCdTe epilayers. Secondary ion mass spectroscopy depth profiling has been performed to characterize ¹H and ²H incorporation. It has been found that H can be controllably incorporated in HgCdTe epilayers to levels in the 10¹⁴ cm⁻³ to 10¹⁸ cm⁻³ range while maintaining the sample at temperatures lower than 60°C. Profiles indicate that H accumulates in regions of known high defect density or in highly strained regions. Analysis of the H depth profile data indicates that the current density-time product is a good figure of merit to predict the H levels in the HgCdTe epilayer. There are progressive differences in the ¹H and ²H uptake efficiencies as a function of depth. Magneto-Hall measurements show consistently higher mobilities at low temperatures for majority carriers in hydrogenated samples.     

Conducting Flame-Sprayed Al Coatings on Textile Fabrics

Electrical conductive and flexible flame-sprayed Al coatings using powder and wire as raw material were successfully deposited onto diverse textile fabrics. The influences of the raw materials, spraying parameters, and fabric materials on the electrical conductivity and microstructure of the metal-fabric composites were investigated. A first series of experiments showed that a coating quantity higher than 20 mg/cm² is necessary for a very good surface conductivity. After the optimization of the spraying parameters, such as a reduced standoff distance and the use of a cooling setup, a high surface conductivity (∼500 S _A) was obtained, which is attributed to a better melting of the spray particles. The improvement in conductivity enables a reduction of the coating quantity, and therefore, the flexibility of the fabric materials is better conserved. This study showed that optimized electrically conductive composites onto flexible fabrics can be produced, without any preliminary thermal or chemical fabric specifications.     

Kinetic data and substrate specificity of a keratinase from Chryseobacterium sp. strain kr6

BACKGROUND: Keratinases are important enzymes for biotechnological processes involving keratin hydrolysis. In this work substrate specificity and kinetic properties of a keratinase from Chryseobaterium sp. were investigated. RESULTS: The optimal conditions for activity of purified keratinase with respect to pH, temperature and sodium chloride concentration were established using factorial design and surface response techniques. The optimum conditions for keratinase activity were pH from 7.4 to 9.2, temperature from 35 °C to 50 °C and NaCl concentration from 50 to 340 mmol L^?1, having azocasein as substrate. Subsequently, the kinetic parameters for this substrate were determined to be K_m = 0.75 mg mL^?1 and V_max = 59.5 U min^?1. The K_i value for 1,10‐phenanthroline was estimated at 0.78 mmol L^?1. The enzyme specificity was evaluated over different synthetic and insoluble substrates. The protease exhibited specificity with selectivity for hydrophobic and positively charged residues. In relation to the insoluble substrates, the enzyme hydrolyzed preferably chicken nails. CONCLUSIONS: This enzyme effectively hydrolyzes insoluble keratin substrates. The knowledge of keratinase properties is an essential step in the development of biotechnological processes involving keratin hydrolysis. Copyright © 2008 Society of Chemical Industry     

A cavity‐backed quad‐slot antenna with novel aperture‐coupled feed for circular polarization

This article describes a novel aperture‐coupled feed, for the excitation of a cavity‐backed quad‐slot antenna with circular polarization. Firstly, a quad‐slot cavity‐backed antenna with linear polarization (LP) is proposed. Then, a novel aperture‐coupled feed, which is composed of a cross‐shaped coupling aperture and a T‐shaped feeding microstrip line, will be applied to this LP antenna. By differing the lengths of the four radiation slots together with the novel aperture‐coupled feed, 90° phase difference and equal magnitude between the radiations from the two pairs of slots can be generated. As a result, a good performance of axial ratio will be achieved for the proposed antenna. A prototype is fabricated at Ka band for a demonstration. Investigations show that the antenna can present a minimum axial ratio (AR) of only about 0.37 dB, as well as a fractional AR bandwidth of about 0.94%. A relative high gain of 6.9 dBic at 32.1 GHz is also achieved for the prototype. The proposed substrate integrated cavity backed antenna with circularly polarization has great potential to be integrated into millimeter‐wave transceiver modules. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:588–594, 2016.     

Spatial ordering of self-organized InGaAs/AlGaAs quantum disks on GaAs (311)B substrates

We report the control of self-organization of In_xGa_1−xAs/AlGaAs quantum disks on GaAs (311)B surfaces using a novel technique based upon lithography-defined SiN dot arrays. A strained InGaAs island array selectively grown using the SiN dots provides periodic strain field. When the pitch of lateral ordering corresponds with the period of the strain field, self-organized quantum disks stacked on the InGaAs islands are precisely arranged just as the buried SiN dot array. The spacing of the array element is 250–300 nm (x = 0.3) and around 150 nm (x = 0.4). Vertical alignment by strain is achieved at a very thick (95 nm) separating layer. Characterization using atomic force microscopy reveals the size-fluctuation of disk is dramatically improved with spatial ordering.