Characterisation of novel magnetic materials using the USANSPOL technique

USANSPOL is a novel ultra-small-angle scattering technique with polarised neutrons for investigation of magnetic materials. It represents a polarised neutron extension to traditional USANS which works with unpolarised neutrons. The high angular resolution of this technique relies on the narrow reflection width of perfect crystal reflections and is employed in a double-crystal diffractometer. Corresponding to the μrad resolution of the set-up, micro-structures of the order of a few tenths of a micrometre up to a few tens of micrometres may be investigated. Neutron polarisation is achieved by insertion of birefringent magnetic prisms between the monochromator crystal and the sample. Rocking the analyser crystal produces a scattering pattern for both neutron spin states in a single measurement but well separated in reciprocal space. By this technique, we have recently studied various amorphous Galfenol soft-magnetic ribbons which were produced by spinning from melt at different manufacturing conditions. USANSPOL allows for a determination of domain sizes of the non-magnetised samples and a study of the growing of magnetically homogeneous regions with increasing externally applied magnetic field. The manufacturing process of the ribbons is reflected in the magnetic micro-structure of the different specimens.     

Integrated optical filter arrays fabricated by using the combinatorial etching technique

A combinatorial etching technique is developed to fabricate integrated narrow bandpass filters on a single substrate. It is highly efficient for fabrication of integrated filter arrays in optical regions. A monolithic filter array has been fabricated by using the technique with a two-step deposition process. The filter contains 32 elements in the near-infrared region. The relative full width at half-maximum (FWHM) sigmalambda/lambda of the filter elements is less than 0.2%. Such a narrow bandpass filter array can be utilized in many optical applications.     

一种弹性盘光纤加速度传感器的探讨

本文介绍了一种采用Ｍａｃｈ－Ｚｅｎｄｅｒ干涉仪结构的中心固支弹性盘光纤加速度传感器。该传感器利用弹性盘的变形引起光纤长度的变化，进而引起位相的变化，通过干涉仪感测出。文中分析了两种结构，并加以实现与对比。     

采用GRIN透镜的数字式光纤加速度计系统设计

为使测量加速度计的传感器小型化、不受电磁干扰 ,根据GRIN透镜在 1 / 4波节处具有入射光线与出射光线成中心对称的特性[1 ] ,首次提出并研制了采用GRIN透镜的微型光纤加速度计。闭环负反馈电路设计技术被应用于该加速度计中 ,使之成为一个具有调宽脉冲再平衡性能的新颖加速度测量系统。通过对该系统进行数字仿真和精度定量分析 ,结果表明 ,该光纤加速度计具有测量线性范围宽、精度高的特点 ,可广泛应用于惯性测控系统中     

16 × 1 integrated filter array in the MIR region prepared by using a combinatorial etching technique

A combinatorial etching technique is introduced to prepare integrated narrow bandpass filters in the mid-infrared (MIR) region. In this region, a 16×1 filter array has been fabricated successfully with two deposition processes combined with the combinatorial etching technique. The pass bands of the 16 filter elements range from 2.534 to 2.859 μm with bandwidth (BW_{3 dB}) less than 0.013 μm (BW_{3 dB}/λ≤0.48%). The insertion loss of the pass bands is between 1.75 and 3.43 dB. The results show that the technique is effective for the fabrication of filter arrays in the MIR region and can be extended to most of the important optical regions. PACS 42.79.Ci; 84.30.Vn; 42.82.Cr; 42.82.Gw     

128 channels of integrated filter array rapidly fabricated by using the combinatorial deposition technique

A combinatorial deposition technique is developed to fabricate integrated narrow bandpass filters (NBPFs) on a single substrate. It is highly efficient for the fabrication of integrated filter arrays in optical regions. An array integrated with 128 NBPFs has been fabricated by using the technique in a nine-step deposition process. The pass bands of the filters distribute almost linearly in the range of 722.0∼880.0 nm. The relative bandwidth of the pass bands is smaller than 0.44%. Such a NBPF array can be utilized as a wavelength division component in many optical applications. It is very powerful for the miniaturization of relevant apparatuses. PACS 42.79.Ci; 84.30.Vn; 42.82.Cr; 42.82.Gw     

Refractive index profile optimisation for the design of optical fibres

Owing to advanced manufacturing techniques, it is possible to produce cylindrical single-mode fibres with nearly arbitrary refractive index profiles. For the design of optical fibres automated optimisation schemes have yet to be exploited. We have employed deterministic local, and stochastic global optimisation schemes for the minimisation of a cost function based on dispersion, dispersion slope, macro-bending losses and mode-field diameter, on the space of continuous piecewise linear dopant concentration profiles. For the local schemes (modified and quasi Newton), it appears possible to select a few initial profiles, such that the optimisation results are close to the “global optima” (within 8%), found using global schemes (simulated annealing and differential evolution), while reducing computation times significantly (minutes instead of days). For the local schemes, the cost function gradient is required. Fréchet derivatives are more efficient than finite-difference approximations. A sensitivity analysis provides useful information for manufacturers regarding the required profile accuracy. A comparison of our optimised fibre designs with commercially available optical fibres demonstrates that existing fibres can be improved.     

Optimization of the synthesis of peptide combinatorial libraries using a one-pot method

Summary Conditions for the synthesis of synthetic peptide combinatorial libraries (SPCLs) from mixtures of amino acids were explored. In a one-pot synthesis, the effect of the starting concentrations of amino acids on the resulting library composition was studied, and the optimum balance of amino acids was determined. Protein sequencing, MALDI-TOF, and amino acid analysis were used for the evaluation of the libraries, and their relative merits are discussed. The effects of continuous-flow automated synthesis instrumentation in conjunction with polyethylene glycol-polystyrene (PEG-PS) graft supports and various cleavage cocktails on the successful synthesis of SPCLs were examined.Abbreviations AA amino acid - Boc tert-butyloxycarbonyl - tBu tert-butyl - Bzl benzyl - DIEA N,N-diisopropylethylamine - DMF N,N-dimethylformamide - ESI-MS electrospray ionization mass spectrometry - Fmoc 9-fluorenylmethyloxycarbonyl - HATU N-[(dimethylamino)-1H-1,2,3triazolo[4,5-b]pyridin-1-ylmethylene]-N-methylmethanamimum hexafluorophosphateN-oxide - HOAt 1-hydroxy-7-azabenzotriazole - HPLC highperformance liquid chromatography - MALDI-TOF matrix-assisted laser desorption ionization/time of flight - MBHA methylbenzhydrylamine - PAL 5-(4-(9-fluorenylmethyloxycarbonyl)aminomethyl-3,5-dimethoxyphenoxy)valeric acid handle - PEG-PS polyethylene glycol-polystyrene graft supports - Pbf 2,2,4,6,7-pentamethylfuran-5-sulphonyl - PNA peptide nucleic acid - PTH phenylthiohydantion - PS polystyrene - Reagent R TFA-thioanisole-1,2-ethanedithiol-anisole (90:5:3:2) - SPCL synthetic peptide combinatorial library - Trt triphenylmethyl - TFA trifluoroacetic acid Amino acids and peptides are abbreviated and designated following the rules of the IUPAC-IUB Commission of Biochemical Nomenclature [J. Biol. Chem., 247 (1972) 977–983]. Amino acid symbols denote thel-configuration unless indicated otherwise.Parts of this paper were presented at the 4th International Symposium on Solid Phase Synthesis and Combinatorial Chemical Libraries, Edinburgh, Scotland, U.K., September 12–16, 1995.     

Study of wind characteristics at heights of 200 to 800 meters using a decimeter sodar

The results of the experiment carried out in July–August 1997 using a two-position sodar are reported. Different types of intensity and spectrum variations of scattered acoustic signals have been obtained. The possibilities of using the sodar for the study of atmospheric turbulence and search of signals caused by “Fresnel” scattering from “plane” irregularities are discussed. Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 7, pp. 841–848, July, 1998.     

Characterisation of nanomaterial hydrophobicity using engineered surfaces

Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors.

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Graphical abstract Determination of hydrophobicity character of nanomaterials by measuring their affinity to engineered surfaces.

     

Implementation of parallel adder using combinatorial logic architecture

The algorithm and optical implementation of full parallel adder using combina-torial logic architecture have been suggested in this paper.The hybrid full parallel adder,which can perform multiple bits addition simultaneously,is implemented by utilizing VLSItechnology and acoustooptic Bragg cells.The algorithm has the advantages of high parallelismand easy optical implementation.The full parallel adder finishes n-bit addition within the du-ration T_d if the pipeline architecture is employed,whose hardware complexity is O(n~2).     

In-process sensor for surface profile measurement applying a common-mode rejection technique

An optical non-contact profilometer is presented for super-smooth surfaces, which applies a so-called common-mode rejection technique. Environmental disturbances and laser amplitude noise, which commonly exist in similar instruments, are overcome in this system. The overall simplicity of the optics and electronics, the low cost of the components and the ease of alignment make this a convenient system to implement.     

Improvement and optimization of high-precision accelerometer based on first-order diffraction using single-layer grating

Optical Review - In this paper, a high-precision accelerometer based on single-level diffraction of a single grating is optimized and improved. The sensor consists of an optical system displacement...     

Discovery of a herbicidal lead using polymer-bound activated esters in generating a combinatorial library of amides and esters

Summary A combinatorial library containing mixtures of amides and esters was prepared through solid-phase chemistry. The advantages of using solid-phase chemistry over solution-phase chemistry to prepare this library are discussed. The library was screened through a high-throughput whole organism herbicidal assay upon which a mixture containing amides was found to have herbicidal activity. Deconvolution of the mixture providedN-(3-benzoylphenyl)-3-(1,1-dimethylethyl)-1-methyl)-1H-pyrazole-5-carboxamide as a herbicidal lead with broadleaf and narrowleaf pre-emergence herbicidal activity as low as 100 g/ha on some weed species. This study represents the first report of an agrochemical discovered using a combinatorial approach. Supplementary Material, comprising experimental procedures for the preparation of resin II and the reaction of II with nucleophiles, GC/MS and LC/MS data for the reaction ofII with morpholine, and a detailed experimental for the preparation of 2 with characterization data, is available upon request.     

Theoretical and experimental demonstrations of a microfiber-based flexural disc accelerometer

The proof-of-concept demonstration of a microfiber-based flexural disc accelerometer is presented. The reduced microfiber size and bending radii give rise to high device compactness and responsivity. A flexural disc accelerometer manufactured from a 10 mm long microfiber showed a performance of ~2.2 rad/g, with the responsivity expected to increase proportionally with the microfiber length.     

Fatigue damage detection using a speckle-contrast technique

An optical setup based on speckle-contrast measurement is proposed as an alternative to analyze fatigue damage on surfaces of metal samples. Based on the dispersion of the light, generated by a laser beam reflected by the surface, roughness and fatigue damage are analyzed after a specially designed fatigue test of metallic samples. The experimental results are obtained from an aluminum alloy type A319 modified with strontium with nodular silicon precipitates that was subjected to a fatigue procedure based in the norm ASTM E647.     

Holographic image subtraction using a polarization technique

A holographic image subtraction technique is proposed. The vector nature of light is utilized in introducing a phase difference of π between the two reconstructed object waves. The experimental results are also presented.     

Synthesis of palladium nanoshell using a layer-by-layer technique

Complete palladium nanoshells were prepared by reducing palladium ions in a one-step reaction onto preformed silica cores of ca. 90 nm, which had been coated with successive layers of poly(diallyldimethyl ammonium chloride), poly(sodium styrenesulfonate) and finally poly(diallyldimethyl ammonium chloride) to reverse the zeta potential of the silica cores. This constitutes the first reported method for complete palladium nanoshell formation without the use of other metals as nucleation sites. The morphology of the nanoshell is of the rough discrete particle type rather than the smooth continuous type.     

Structural investigations of ITO-ZnO films grown by the combinatorial pulsed laser deposition technique

Mixtures of transparent and conductive oxides such as ITO-ZnO have been grown by a combinatorial pulsed laser deposition technique from two targets that were located 15 mm apart. The films were deposited on (1 0 0)Si and quartz substrates that were heated at temperatures from 300 to 500 °C. Measurements of the In to Zn ratios along the transversal axis of the substrates, which passes through the maximum thickness points corresponding to each target position were performed using energy dispersive X-ray spectroscopy and spectroscopic ellipsometry. From simulations of the X-ray reflectivity spectra, collected with a 2 mm mask on different locations along the transversal axis of the samples, the density and thickness of the deposited films were calculated and then the In to Zn ratios. The crystalline structure and electrical properties of the deposited films were also investigated along the same axis. Changes in the ratio of In/Zn along this axis resulted in changes of the film lattice constant and texture.