Light transmission instrument for particle size analysis of colloidal dispersions

A simple light transmission instrument is described which enables average droplet sizes to be determined quickly and accurately. Light scattering is minimized by the use of a small-divergence laser beam and pinhole detectors, and by situating the sample photodetector relatively far from the sample. Good signal stability is ensured by the use of a double-beam configuration, the second beam serving as reference. The transmission of the sample is obtained from the time average ratio of the two signals. Use of a linearly polarized laser further increases accuracy and stability.Results of experiments with particles in the size range 0.8 – 50 μm show good agreement with Coulter counter analyses.     

Effect of Melt Conditioning on Removal of Fe from Secondary Al-Si Alloys Containing Mg,Mn, and Cr

Metallurgical and Materials Transactions A - Primary intermetallic sludge formation in hypoeutectic secondary Al7.1Si(1.5-xM)FexMM alloys was investigated in view of potential Fe removal by...     

Broad-beam transmission data for new brachytherapy sources, Tm-170 and Yb-169

The characteristics of the radionuclides (170)Tm and (169)Yb are highly interesting for their use as high dose-rate brachytherapy sources. The introduction of brachytherapy equipment containing these sources will lead to smaller required thicknesses of the materials used in radiation protection barriers compared with the use of conventional sources such as (192)Ir and (137)Cs. The purpose of this study is to determine the required thicknesses of protection material for the design of the protecting walls. Using the Monte Carlo method, transmission data were derived for broad-beam geometries through lead and concrete barriers, from which the first half value layer and tenth value layer are obtained. In addition, the dose reduction in a simulated patient was studied to determine whether transmission in the patient is a relevant factor in radiation protection calculations.     

Bestimmung der Aktivitäten von Lipase,Lipoxygenase und Peroxidase in nativen und extrudierten Getreidekleien

To avoid fat deterioration in grain products during storage the cereal inherent enzymes lipase, lipoxygenase and peroxidase have to be inactivated. Known methods for the determination of the enzymes activity are tested and their applicability evaluated. Own optimized methods are presented. In laboratory and semiindustrial extrusion tests (laboratory single screw extruder, twin screw extruder, short screw extruder) the degree of enzyme inactivation of wheat bran, rye and maize bran, and oat bran is determined in dependence on the extrusion parameters. The enzymes mentioned already had been inactivated at mild extrusion conditions (temperature <20° C, moisture 20%, low mechanical stress). Only in brans of high fat content (10–14%) or high moisture (>25%) minor residual activities of peroxidase and lipase were observed.     

Modification of biologically active peptides: production of a novel lipohexapeptide after engineering of Bacillus subtilis surfactin synthetase

The Bacillus subtilis strain ATCC 21332 produces the lipoheptapeptidesurfactin, a highly potent biosurfactant synthesized by a largemultimodular peptide synthetase. We report the genetic engineeringof the surfactin biosynthesis resulting in the production ofa novel lipohexapeptide with altered antimicrobial activities.A combination of in vitro and in vivo recombination approacheswas used to construct a modified peptide synthetase by eliminatinga large internal region of the enzyme containing a completeamino acid incorporating module. The remaining modules adjacentto the deletion were recombined at different highly conservedsequence motifs characteristic of amino acid incorporating modulesof peptide synthetases. The primary goal of this work was toidentify permissive fusion sites suitable for the engineeringof peptide synthetase genes by genetic recombination. Analysisof the rearranged enzymes after purification from B.subtilisand from the heterologous host Escherichia coli revealed thatthe selection of the recombination site is of crucial importancefor a successful engineering. Only the recombination at a specificHHIIxDGVS sequence motif resulted in an active peptide synthetase.The expected lipohexapeptide was produced in vivo and firstevidence of a reduced toxicity against erythrocytes and an enhancedlysis of Bacillus licheniformis cells was shown.     

Molecular Inversion Probe-Based Sequencing of USH2A Exons and Splice Sites as a Cost-Effective Screening Tool in USH2 and arRP Cases

A substantial proportion of subjects with autosomal recessive retinitis pigmentosa (arRP) or Usher syndrome type II (USH2) lacks a genetic diagnosis due to incomplete USH2A screening in the early days of genetic testing. These cases lack eligibility for optimal genetic counseling and future therapy. USH2A defects are the most frequent cause of USH2 and are also causative in individuals with arRP. Therefore, USH2A is an important target for genetic screening. The aim of this study was to assess unscreened or incompletely screened and unexplained USH2 and arRP cases for (likely) pathogenic USH2A variants. Molecular inversion probe (MIP)-based sequencing was performed for the USH2A exons and their flanking regions, as well as published deep-intronic variants. This was done to identify single nucleotide variants (SNVs) and copy number variants (CNVs) in 29 unscreened or partially pre-screened USH2 and 11 partially pre-screened arRP subjects. In 29 out of these 40 cases, two (likely) pathogenic variants were successfully identified. Four of the identified SNVs and one CNV were novel. One previously identified synonymous variant was demonstrated to affect pre-mRNA splicing. In conclusion, genetic diagnoses were obtained for a majority of cases, which confirms that MIP-based sequencing is an effective screening tool for USH2A. Seven unexplained cases were selected for future analysis with whole genome sequencing.     

Histological image retrieval based on semantic content analysis

The demand for automatic recognition and retrieval of medical images for screening, reference, and management is increasing. We present an intelligent content-based image retrieval system called I-Browse, which integrates both iconic and semantic content for histological image analysis. The I-Browse system combines low-level image processing technology with high-level semantic analysis of medical image content through different processing modules in the proposed system architecture. Similarity measures are proposed and their performance is evaluated. Furthermore, as a byproduct of semantic analysis, I-Browse allows textual annotations to be generated for unknown images. As an image browser, apart from retrieving images by image example, it also supports query by natural language.     

An interpretation of Mahalanobis distance in the dual space

Using the concept of a dual space, nk-dimensional vectors can be viewed as k points in an n-dimensional co-ordinate system. The relationships between the basic statistical properties of a k-variate sample and the geometrical properties of such a space are developed and the concept extended to two samples drawn from different populations, with derivation of the geometrical meaning of Mahalanobis distance. This geometrical approach provides valuable insight into why different feature subsets may or may not have high discriminatory potential, and shows that clustering in the dual space, or its subspaces, does not necessarily yield an effective feature selection technique.