Electrophoretic deposition of bacterial cells

The possibility to use alternating current electrophoretic deposition (AC-EPD) to deposit living cells in the form of Staphylococcus aureus and Escherichia coli on stainless steel was assessed. The experimental results revealed that these bacteria can be successfully deposited on metallic surfaces from demineralized water and sucrose based solutions using asymmetric unbalanced electric fields. Cell viability of the deposited bacteria was influenced by the strain and deposition medium.     

Electrophysiological Responses of Bactrocera kraussi (Hardy) (Tephritidae) to Rectal Gland Secretions and Headspace Volatiles Emitted by Conspecific Males and Females

Pheromones are biologically important in fruit fly mating systems, and also have potential applications as attractants or mating disrupters for pest management. Bactrocera kraussi (Hardy) (Diptera: Tephritidae) is a polyphagous pest fruit fly for which the chemical profile of rectal glands is available for males but not for females. There have been no studies of the volatile emissions of either sex or of electrophysiological responses to these compounds. The present study (i) establishes the chemical profiles of rectal gland contents and volatiles emitted by both sexes of B. kraussi by gas chromatography–mass spectrometry (GC–MS) and (ii) evaluates the detection of the identified compounds by gas chromatography–electroantennogram detection (GC–EAD) and –electropalpogram detection (GC–EPD). Sixteen compounds are identified in the rectal glands of male B. kraussi and 29 compounds are identified in the rectal glands of females. Of these compounds, 5 were detected in the headspace of males and 13 were detected in the headspace of females. GC–EPD assays recorded strong signals in both sexes against (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, 2-ethyl-7-mehtyl-1,6-dioxaspiro[4.5]decane isomer 2, (E,Z)/(Z,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, and (Z,Z)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane. Male antennae responded to (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane, 2-methyl-6-pentyl-3,4-dihydro-2H-pyran, 6-hexyl-2-methyl-3,4-dihydro-2H-pyran, 6-oxononan-1-ol, ethyl dodecanoate, ethyl tetradecanoate and ethyl (Z)-hexadec-9-enoate, whereas female antennae responded to (E,E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane and 2-methyl-6-pentyl-3,4-dihydro-2H-pyran only. These compounds are candidates as pheromones mediating sexual interactions in B. kraussi.     

Electrophoretic deposition as a tool for separation of protein inclusion bodies from host bacteria in suspension

This paper shows, for the first time, that the electrophoretic deposition technique is able to selectively collect protein inclusion bodies (PBs) from the host bacteria suspensions. In the first step, zeta potential as a function of pH is carefully determined for both species involved. Based on the obtained dependencies, the pH of the mixture of PBs and bacteria is precisely adjusted and the electrophoretic experiment is carried out. We show that the efficiency of separation and the yield depends not only on the electrokinetic properties of given species but also on the electrode composition and surface morphology. The deposited species are easily removed by forced washing or reverse electric field. As a whole, the selectivity and the yields are higher than in most alternative state-of-the art techniques.     

位错对BBO晶体光学均匀性的影响

本文报道了BBO晶体中位错密度对光学均匀性的影响.样品的光学均匀性是利用Wyko RTI 4100型干涉仪进行测量.采用侵蚀法观测BBO晶体{001}面的位错密度,在一定的侵蚀条件下,观察到BBO晶体{001}面上的位错露头为突起的正三方锥形,底边与X轴平行.在显微镜下测量出样品的蚀坑密度.实验证明,随着位错密度的增加BBO晶体的光学均匀性逐渐变差.     

High performance anode-supported intermediate temperature solid oxide fuel cells (IT-SOFCs) with La0.8Sr0.2Ga0.8Mg0.2O3−δ electrolyte films prepared by electrophoretic deposition

Remarkable power density was obtained for anode-supported solid oxide fuel cells (SOFCs) based on La_0.8Sr_0.2Ga_0.8Mg_0.2O_3−δ (LSGM) electrolyte films, fabricated following an original procedure that allowed avoiding undesired reactions between LSGM and electrode materials, especially Ni. Electrophoretic deposition (EPD) was used for the fabrication of 30 μm-thick electrolyte films. Anode supports were made of La_0.4Ce_0.6O_2−x (LDC). The LSGM powder was deposited by EPD on an LDC green tape-cast membrane added with carbon powder, both as pore former and substrate conductivity booster. A subsequent co-firing step at 1490 °C produced dense electrolyte films on porous LDC skeletons. Then, a La_0.8Sr_0.2Fe_0.8Co_0.2O_3−δ (LSFC) cathode was applied by slurry-coating and calcined at 1100 °C. Finally, the porous LDC layer was impregnated with molten Ni nitrate to obtain, after calcination at 900 °C, a composite NiO–LDC anode. Maximum power densities of 780, 450, 275, 175, and 100 mW/cm² at 700, 650, 600, 550, and 500 °C, respectively, were obtained using H₂ as fuel and air as oxidant, demonstrating the success of the processing strategy. As a comparison, electrolyte-supported SOFCs made of the same materials were tested, showing a maximum power density of 150 mW/cm² at 700 °C, more than 5 times smaller than the anode-supported counterpart.     

Application of Raman spectroscopy to study of the polymer foams modified in the volume and on the surface by carbon nanotubes

Polylactide nanocomposites with multi-walled carbon nanotubes (PLA/MWCNT) in the form of porous foams made of a biocompatible, biodegradable and environmentally friendly polymer with a small amount of carbon nanotubes, were investigated in this work. Additionally, PLA/MWCNT porous nanocomposites were coated with MWCNTs using the electrophoretic deposition method (EPD). All samples were characterized by a porosity of about 90%, showing pore sizes in the range of 100 to 200 μm, for PLA/MWCNT foam, however, EPD deposition resulted in an decrease in the number of smaller pores in PLA/MWCNT + MWCNT (EPD) foam. The porous polymer (PLA) matrix, shows almost twofold increase in crystallinity while depth penetrating the volume of the sample. The crystallinity, of the PLA/MWCNT foam, at first is growing then it gradually lowers, while for the PLA/MWCNT + MWCNT(EPD) foam almost does not change. This behavior points toward significant distinction between surface and interior of the samples. A detailed analysis of Raman spectra indicates related carbon structures occurring in the nanomaterial foams: graphene and graphite phases, CNT and also carbon amorphous phases. The characteristics of a single-shell vibration are visible by the character of the G-band. The estimated crystallite size in PLA/MWCNT + MWCNT(EPD) is about 3 times smaller than that in the PLA/MWCNT.     

Preparation of titania microfiltration membranes supported on porous Ti–Al alloys

A TiO₂ membrane supported on a planar porous Ti–Al alloy was prepared by combination of electrophoretic deposition and dip-coating. In the electrophoretic deposition process, the membrane thickness increased linearly with the square root of the deposition time, while increased with decrease of the suspension viscosity. The perfect TiO₂/Ti–Al composite membrane was obtained by further dip-coating modification. SEM images showed that the surface of the membrane was defect-free. XRD result indicated that rutile TiO₂ still remained in the membrane bulk as the main phase, while a new phase titanium oxides with the form of Ti_xO_y, where y is less than 2x, was also observed. The supported TiO₂/Ti–Al composite membrane had an average pore size of 0.28 μm, a thickness of 40 μm or so and a pure water flux of 3037 L m⁻² h⁻¹ bar⁻¹.     

Evaluation of threading dislocation density of strained Ge epitaxial layer by high resolution x-ray diffraction

The analysis of threading dislocation density(TDD)in Ge-on-Si layer is critical for developing lasers,light emitting diodes(LEDs),photodetectors(PDs),modulators,waveguides,metal oxide semiconductor field effect transistors(MOS-FETs),and also the integration of Si-based monolithic photonics.The TDD of Ge epitaxial layer is analyzed by etching or transmission electron microscope(TEM).However,high-resolution x-ray diffraction(HR-XRD)rocking curve provides an optional method to analyze the TDD in Ge layer.The theory model of TDD measurement from rocking curves was first used in zinc-blende semiconductors.In this paper,this method is extended to the case of strained Ge-on-Si layers.The HR-XRD 2θ/ωscan is measured and Ge(004)single crystal rocking curve is utilized to calculate the TDD in strained Ge epitaxial layer.The rocking curve full width at half maximum(FWHM)broadening by incident beam divergence of the instrument,crystal size,and curvature of the crystal specimen is subtracted.The TDDs of samples A and B are calculated to be 1.41×10~8cm~(-2)and 6.47×10~8cm~(-2),respectively.In addition,we believe the TDDs calculated by this method to be the averaged dislocation density in the Ge epitaxial layer.     

GaSb layers with low defect density deposited on (001) GaAs substrate in two-dimensional growth mode using molecular beam epitaxy

We report on the growth of fully relaxed and smooth GaSb layers with reduced density of threading dislocations, deposited on GaAs substrate. We prove that three parameters have to be controlled in order to obtain applicable GaSb buffers with atomically smooth surface: interfacial misfit (IMF), the etch pit density (EPD) and the growth mode.The GaSb/GaAs interfacial misfit array and reduced EPD ≤1.0 × 10⁷ cm^?2 were easily obtained using As-flux reduction for 3 min and Sb-soaking surface for 10 s before the GaSb growth initiation. The successive growth of GaSb layer proceeded under the technological conditions described by the wide range of the following parameters: r_G ∈ (1.5 ÷ 1.9) Å/s, T_G ∈ (400 ÷ 520)°C, V/III ∈ (2.3 ÷ 3.5). Unfortunately, a spiral or 3D growth modes were observed for this material resulting in the surface roughness of 1.1 ÷ 3.0 nm. Two-dimensional growth mode (layer by layer) can only be achieved under the strictly defined conditions. In our case, the best quality 1-μm-thick GaSb buffer layer with atomically smooth surface was obtained for the following set of parameters: r_G = 1.5 Å/s, T_G = 530 °C, V/III = 2.9. The layer was characterized by the strain relaxation over 99.6%, 90° dislocations array with the average distance of 5.56 nm, EPD ～8.0 × 10⁶ cm^?2 and 2D undulated terraces on the surface with roughness of about 1 ML. No mounds were observed. We belive that only thin and smooth GaSb layer with reduced EPD may be applied as the buffer layer in complex device heterostructures. Otherwise, it may cause the device parameters deterioration.