Laser annealing of GaAs dual implanted with Si and P ions

Laser annealing of SI(100) GaAs:Cr implanted either with Si⁺ ions (150 keV, 6×10¹³-1×10¹⁵cm^–2) or dual implanted with Si⁺ ions (150 keV, 6×10¹⁴–1×10¹⁵cm^–2) and P⁺ ions (160 keV, 1×10¹⁴–1×10¹⁵cm^–2) has been examined using backscatteringchannelling technique and via electrical measurement of Hall effect. It has been found that at laser energy densities 0·8 J cm^–2 a full recovery of the sample surface occurs. In dual implanted samples (1×10¹⁵ Si⁺ cm^–2+1×10¹⁵P⁺cm^–2) up to 46% of Si atoms become electrically active after the laser annealing. Resultant Hall mobility of carriers is, however,lower than that obtained after common thermal annealing.The authors are pleased to take the opportunity of thanking Professor M. Kubát for his encouragement and continuous support. Accelerator staff is gratefully acknowledged for its assistance in the course of experiments.     

Odd‐even effect during layer‐by‐layer assembly of polyelectrolytes inspired by marine mussel

Biomimetic polyelectrolyte of Dopa modified poly(acrylic acid) (PAADopa) was synthesized taking advantage of Dopa, the major unit of marine adhesive proteins. Zinc crosslinked PAADopa (PAADopa‐Zn) were formed at acidic pH for more compact structure and assembled with the positively charged polyethylenimine (PEI) to build robust polyelectrolyte multilayers at high salt concentration. Effects of pH, crosslinking degree, and salt concentration on polymer structure, film building process, and morphology were investigated, respectively. An “odd‐even” effect was observed by quartz crystal microbalance with dissipation and AFM in the presence of zinc ion, which becomes more obvious with an optimum crosslinking degree (Zn/Dopa = 2.0) under high salt concentration (0.6 M NaCl). It indicates the different swollen properties of PEI chain and PAADopa‐Zn complexes during the layer‐by‐layer building process under optimum crosslinking degree of PAADopa‐Zn at high salt concentration. Such odd‐even phenomenon of the biocompatible system is of critical importance for understanding the mechanism of layer formation and film structures. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 245–255     

Vapor pressure of selected aliphatic alcohols by ebulliometry. Part 1

Vapor pressures for liquid 2,2-dimethyl-1-propanol (CAS Registry Number 75-84-3), 1-hexanol (CAS Registry Number 111-27-3), 1-heptanol (CAS Registry Number 111-70-6), 1-octanol (CAS Registry Number 111-87-5) and 1-tetradecanol (CAS Registry Number 112-72-1) were measured by the precision comparative ebulliometry over an approximate pressure range from 8 to 100 kPa. The relative uncertainty in pressure is estimated to be less than or equal to 0.05% of the measured value and the absolute uncertainty in temperature is estimated at less than or equal to 0.01 K on ITS-90. The results are represented by the Antoine equation and compared with available literature data. A new transformation of vapor pressure data, which facilitates the detection of systematic errors, is presented.     

ELISA kit for determination of egg white proteins: interlaboratory study

An interlaboratory study was conducted in 11 laboratories to validate an ELISA method developed for the quantitative determination of egg white proteins (EWPs) in foods. The ELISA kit used for this study is based on sheep polyclonal antibody. It does not produce any false-positive results or cross-reactivity in a broad food matrix range with zero EWP content. All participants obtained the Egg ELISA Kit-native with standard operational procedure and the list of samples, as well as the samples and a protocol for recording test results. The study included 10 food samples. Four samples of food matrix with zero EWP content showed EWP content lower than the first standard (EWP content 0.5 mg/kg). One sample of food matrix with zero EWP content revealed EWP content higher than standard 3 (1.5 mg EWP/kg). Five food samples containing EWP as an ingredient tested positive and one negative. The statistical tests (Cochran, Dixon, and Mandel) and analysis of variance were used to evaluate the interlaboratory study results. Repeatability and reproducibility limits, as well as LOQ (1.4 mg EWP/kg) and LOD (0.43 mg EWP/kg), were calculated for the kit.     

Photopolymer for Optical Holography and Holographic Interferometry

Summary: In our laboratory, we have continued in experimental study of acrylamide-based photopolymer recording material. Our exposition and detection setup was used for real-time measurements of a diffraction grating formation process. Based on the results of our measurements, the chemical composition of the material was modified to increase sensitivity, value of refractive index modulation and stability of the formed structure. Recently, the material has been successfully applied to holographic interferometry.     

Occurrence and behavior of system peaks in RP HPLC with solely aqueous mobile phases

System peaks are important but often also disturbing phenomena occurring in separation systems. Behavior of system peaks was studied in reversed phase high performance liquid chromatography (RP HPLC) systems consisting of an RP Amide C16 column and aqueous solutions of organic acids with alkaline metal hydroxides as mobile phases. Binary mobile phases, composed of benzoic acid and lithium hydroxide (LiOH) or cesium hydroxide (CsOH), yielded two system peaks. The first peak was stationary and the second one moved with dilution of the mobile phase or with changes of the alkaline metal hydroxide concentration. The latter changes affected dissociation of the benzoic acid present in the mobile phase and thereby its retention. The presumption that the first system peak is not influenced by the type of alkaline metal cation and that it is related to the non‐adsorbed component of the mobile phase was confirmed by a cyclic procedure. Three‐component mobile phases composed of benzoic acid, tropic acid, and a hydroxide gave rise to three system peaks as expected. The first peak was again stationary and the two others shifted depending on the concentration variation of both acids. Resonance causing a zigzag peak, well described in capillary zone electrophoresis (CZE), was observed if 1‐pentanol was injected into a chromatographic system with one‐component mobile phase.