Simple narrow-linewidth 1.5 ?m InGaAsP DFB external-cavity laser

An external-cavity laser consisting of a 1.5 ?m-wavelength antireflection-coated DFB laser chip, a microscope objective and a mirror provides a stable, single-frequency, narrow-linewidth (?f=40 kHz) output. Because the laser operates in the strong feedback regime, it is immune to external optical perturbations. Single-longitudinal-mode operation is maintained by the DFB grating, and the linewidth is reduced by the extended passive cavity.     

Characterisation of frequency response of 1.5 ?m InGaAsP DFB laser diode and InGaAs PIN photodiode by heterodyne measurement technique

The frequency response of an InGaAs PIN photodiode and the ratio of the frequency modulation (FM) index to the intensity modulation (IM) index of a 1.5 ?m InGaAsP vapour-phase-transported DFB laser diode have been measured by an optical heterodyne measurement technique. From the response of the photodiode to the laser radiation beat frequency, a 20 GHz detector bandwidth is determined. The ratio of the FM and IM indices at 3 mW laser output power per facet decreases from 60 at 100 MHz modulation frequency to 3.3 above 2 GHz.     

Processing and characterization of nanostructured Cu-carbon nanotube composites

Carbon nanotube (CNT) reinforced nanostructured Cu matrix composite with a grain size less than 25 nm has been successfully fabricated via a combination of ball milling and high-pressure torsion. CNTs were found to be homogeneously dispersed into the metal matrix, leading to grain refinement with a narrow grain size distribution and significant increase in hardness.     

Starch-Derived Products for Detergents

Recent developments in the formulation of detergents have been driven by a strong consumer demand for natural and biodegradable products. Detergent manufacturers responded to this demand with corresponding products and advertising slogans such as “fully biodegradable”, “natural” or even “double natural” to oust their competitors. In a detergent formulation, starch- derived products can in principle be used for the following purposes: as the hydrophilic head group in surfactants, as the starting material for (poly)carboxylate co-builders and as the backbone of bleaching activators. Non-ionic classical surfactants can be replaced by alkylpolyglucosides (APGs), a class of products completely based on renewable resources such as glucose and fatty alcohols derived from natural fatty acids. Sodium tripolyphosphate (STPP), the product responsible for the eutrophication of surface waters, can be substituted by a combination of an inorganic zeolite and highly oxidised starch (dicarboxylic starch) or by citrate. Acetylated polyols derived from hydrogenated carbohydrates such as sorbitol can take over the function of the petrochemically-based tetraacetyl ethylene diamine (TAED) used as activator to allow perborate bleaching at lower washing temperatures.     

Identification of chemical markers for the sensory shelf-life of saveloy

The aroma composition, the microbial composition and the sensory profile were measured in sliced saveloy samples packed in modified atmosphere (MA). The main objective was to identify aroma compounds with potential as chemical markers to identify the sensory changes of saveloy. The 60 aroma compounds isolated from the saveloy samples by dynamic headspace extraction and measured by Gas Chromatography Mass Spectrometry (GC-MS) were used to model the sensory attributes sour&old odour and meaty odour using partial least squares regression (PLS). 2- and 3-methylbutanal, 2- and 3-methylbutanol, acetoin and diacetyl were found to have the highest impact on both sour&old odour and meaty odour of the samples. The results show that these four aroma compounds have high potential as chemical markers for the sensory shelf-life of sliced and MA-packed saveloy.     

New Carbohydrate Derivatives from Biotechnical and Chemical Processes

Starch, its derivatives and hydrolysis products are well established as industrial products for the food and technical industries. More advanced products, based on starch, are available today, manufactured by biotechnical and chemical processes. They comprise a variety of monomeric compounds like polyols, hydroxycarboxylic acids, glycosides and their derivatives obtained by esterification, etherification and amination. In addition, interesting oligomeric and polymeric products are accessible, based on starch and its derivatives. Selected examples of these products are described as well as their respective production methods. For some products the chemicals synthesis will be compared with the fermentation route, analysing the relative advantages and disadvantages of both. The wide application potential of these “new” products is illustrated with reference to their use in different industries, e. g. in the manufacturing and processing of resins, polymers, detergents, cosmetics, pharmaceuticals and processed foods. Special emphasis will be given to the structural peculiarities of these carbohydrate derivatives, for example chirality, which enables them to act as unique intermediates in the production of biologically active products.     

New Industrial Products from Starch

The industrial (non-food) use of starch and starch-based products as renewable raw materials is discussed together with examples, in the following application areas:

• –Starch as auxiliary raw material: binder, adhesive, thickener, protective colloid.
• –Starch as raw material for new products in chemical or biotechnical processes: polyols, acids, polysaccharides, enzymes.
• –Starch as filler with specific functionality for synthetic polymers to improve application properties in e. g. polyethylene, polypropylene, polystyrene, polyurethane-foams, styrene/butadiene copolymers, polyvinylchloride.
• –Starch as reactive component to be incorporated during production of synthetic polymers leading to synergistic effects: urea/formaldehyde resins, phenolic resins, alkyd- and melamine resins.
• –Starch-based active materials which either exhibit direct functionality themselves, (e. g. as surfactants, sequestrants and bleaching boosters) or which represent building blocks for the synthesis of chiral compounds for the pharmaceutical or the agro-industries.

     

Herstellung von Phenolharzen unter Verwendung von Stärkeprodukten

Usage of Starchy Products for Preparation of Phenolic Resins. Incorporation of starches and starch hydrolysates in phenolic resins of novolak and resol type has been investigated via acid catalyzed dehydration to 5-hydroxymethylfurfural (HMF) in the presence of phenol and formaldehyde. Due to formation of HMF/phenol-condensates savings up to 40% phenol and 65% formaldehyde are possible in comparison to commercial resins. Besides very low amounts of residual monomers, curing is accelerated with increased carbohydrate incorporation, which can be used to reduce time consuming manufacturing processes. Especially starch hydrolysates with different average molecular weights can be used in a very flexible way to achieve special requirements like softening points, mol weight distributions, viscosities and curing behaviour.