Coupled electrical-fluid model of pulsed electric field treatment in a model food system

A coupled electrical-fluid model of a pulsed electric field (PEF) treatment is presented. The modeling of PEF food treatment to date has been limited to a separate study of the electric field distribution and the product flow. A model was developed that couples the electric field and fluid dynamics analysis. The main feature of the model is that parameters vital for the process control, i.e. the product flow and heating and the electric field distribution in a PEF chamber, can be determined self-consistently. Comparison between model predictions and experimental measurements were made for a laboratory scale, co-field treatment chamber configuration of a continuous flow-through PEF unit. The predicted product temperatures downstream of the treatment chamber were in good agreement with the observed temperature for a range of conditions considered. This work is a first step towards developing a reliable tool for the optimization of the PEF treatment chamber geometry.     

80 nm spectrally flattened, high power erbium amplified spontaneousemission fibre source

A novel two-stage spectrally flattened, high output power erbium amplified spontaneous emission (ASE) fibre source pumped using a single laser diode pump is reported. The source has a bandwidth of 80 nm with a 1 dB ripple and output power of +13 dBm (20 mW)     

Dynamics analysis of cavitation disintegration of microparticles during nanopowder preparation in a new Water Jet Mill (WJM) device

A physical analysis of cavitation-based implosive breakage of solid particles focusing on practical application during fine particle disintegration in a liquid suspension is submitted in the present paper. The physical source of the cavitation dynamics phenomena involved is an extreme velocity gradient induced by an ultrahigh-energy liquid jet mixing together with a slow liquid suspension of milled particles. Extreme tensile stresses occurring at velocity gradients over 1000 ms^?1mm^?1 at the operating temperature of 65 °C generates high-intensity pure vapor cavitation in the degassed water dispersion with extreme values of impact pressure in the final of bubble implosions on particle surfaces.Preparation of silicon nanoparticles with median diameter approximately 148 nm using a newly developed “Water Jet Mill” (WJM) device is demonstrated in the present article as an example of application of the aforementioned disintegration method as well as of theoretical analysis of this method. The disintegration method is characterized by a high potential for milling of submicron particles with high efficiency.     

Acute and chronic toxicity effects of silver nanoparticles (NPs) on Drosophila melanogaster

The use of nanoscaled materials is rapidly increasing, however, their possible ecotoxicological effects are still not precisely known. This work constitutes the first complex study focused on in vivo evaluation of the acute and chronic toxic effects and toxic limits of silver nanoparticles (NPs) on the eukaryotic organism Drosophila melanogaster. For the purpose of this study, silver NPs were prepared in the form of solid dispersion using microencapsulation method, where mannitol was used as an encapsulation agent. This newly prepared solid dispersion with a high concentration of silver NPs was exploited to prepare the standard Drosophila culture medium at a silver concentration range from 10 mg·L(-1) to 100 mg·L(-1) of Ag in the case of the acute toxicity testing and at a concentration equal to 5 mg·L(-1) in the case of the chronic toxicity testing. The acute toxic effect of silver NPs on Drosophila melanogaster was observed for the silver concentration equal to 20 mg·L(-1). At this silver concentration, 50% of the tested flies were unable to leave the pupae, and they did not finish their developmental cycle. Chronic toxicity of silver NPs was assessed by a long-term exposure of overall eight filial generations of Drosophila melanogaster to silver NPs. The long-term exposure to silver NPs influenced the fertility of Drosophila during the first three filial generations, nevertheless the fecundity of flies in subsequent generations consequently increased up to the level of the flies from the control sample due to the adaptability of flies to the silver NPs exposure.     

Current Problems and Possible Solutions in High-Temperature Lead-Free Soldering

The substitution of lead in the electronics industry is one of the key issues in the current drive towards ecological manufacturing. Legislation has already banned the use of lead in solders for mainstream applications (T _M ≈ 220 °C), but the use of lead in the solders for high-temperature applications (>85% lead, T _M ≈ 250-350 °C) is still exempt in RoHS2. The search for proper substitutes has been ongoing among solder manufacturers only for a decade without finding a viable low cost alternative and is the subject of intensive research. This article tries to map the current situation in the field of high-temperature lead-free soldering, presenting a short review of current legislation, requirements for substitute alloys, and finally it describes some existing solutions both in the field of promising new materials and new technologies. Currently, there is no drop-in replacement for lead-containing solders and therefore both the new materials and the new technologies may be viable solutions for production of reliable lead-free joints for high-temperature applications.     

A 600-MHz VLIW DSP

A 600-MHz VLIW digital signal processor (DSP) delivers 4800 MIPS, 2400 (16 b) or 4800 (8 b) million multiply accumulates (MMACs) at 0.3 mW/MMAC (16 b). The chip has 64M transistors and dissipates 719 mW at 600 MHz and 1.2 V, and 200 mW at 300 MHz and 0.9 V. It has an eight-way VLIW DSP core, a two-level memory system, and an I/O bandwidth of 2.4 GB/s. The chip integrates a c64X DSP core with Viterbi and turbo decoders. Architectural and circuit design approaches to achieve high performance and low power using a semi-custom standard cell methodology, while maintaining backward compatibility, are described. The chip is implemented in a 0.13-/spl mu/m CMOS process with six layers of copper interconnect.     

A microphysiometer for simultaneous measurement of changes in extracellular glucose, lactate, oxygen, and acidification rate

A microphysiometer capable of measuring changes in extracellular glucose, lactate, oxygen, and acidification rate has been developed by incorporating modified electrodes into a standard Cytosensor Microphysiometer plunger. Glucose and lactate are measured indirectly at platinum electrodes by amperometric oxidation of hydrogen peroxide, which is produced from catalysis of glucose and lactate at films containing their respective entrapped oxidase. Oxygen is measured amperometrically at a platinum electrode coated with a Nafion film, while the acidification rate is measured potentiometrically by a Cytosensor Microphysiometer. Analytical information is obtained during the Cytosensor stop-flow cycles, where the electrodes measure changes in the extracellular medium corresponding to the consumption or production of the analyte by the cells. Modification of the Cytosensor plunger for multianalyte determination is described, and the operation of the technique is illustrated by the simultaneous measurement of all four analytes during the addition of fluoride and DNP to Chinese hamster ovary cells and fluoride and antimycin A to mouse fibroblast cells. Cell metabolic recovery and dynamics after exposure to agents can also be observed in specific cases.     

Fourier transform photocurrent spectroscopy applied to a broad variety of electronically active thin films (silicon, carbon, organics)

Steady state and low frequency photocurrent spectroscopies have proved as a valuable tool for investigation of many different semiconductors, used for example as an absorber in photovoltaic solar cells or in the large area sensors. Fourier transform photocurrent spectroscopy (FTPS), described here, exhibits advantages as a high sensitivity (we demonstrate dynamical range up to 9 orders of magnitude of the optical absorption coefficient, connected with the absorption process leading to free carriers; or sensitivity for dopant detection better than 1 part-per-billion), fast acquisition of data (it can be of the order of seconds) or high resolution (under more lengthy acquisition of data). Results on amorphous silicon, microcrystalline silicon, diamond layers, nanocrystalline diamond and very thin organic films, as poly(2-methoxy-5-(3′,7′-dimethyl-octyloxy))-p-phenylene-vinylene (MDMO-PPV), regioregular poly(3-hexylthiophene (P3HT) and their blends with (6,6)-phenyl-C61-butyric-acid (PCBM) are reported, together with the results measured on various thin film silicon or polymer solar cells.     

Defense Secretion of Prorhinotermes simplex: Toxicity to Insecticide Susceptible and Resistant House Fly

(E)-1-Nitropentadec-1-ene (NPE), the main component of the defense secretion of Prorhinotermes simplex soldiers, is toxic to both insecticide-susceptible (S) as well as to insecticide-resistant (R) strains of the house fly, Musca domestica. The LD₅₀ is 11.7 g/female fly for the S strain and 9.7 g for the R strain. The same efficacy of NPE on R and S strains indicates a different mechanism of action compared to conventional chlorinated, organophosphorus, and pyrethroid insecticides. Termite nestmates are protected against NPE by a specific detoxification mechanism. 1-Nitropentadecane, the detoxification product of NPE is nearly nontoxic to house flies, and doses up to 160 g/fly caused only very low mortality.     

The effective stress function algorithm for pressure-dependent plasticity applied to hot isostatic pressing

An algorithm for unconditionally stable and accurate integration of elasto-viscoplastic pressure-dependent constitutive model is presented. Rate form constitutive equations of thermal-elastoviscoplastic type with compressibility take into account the changes in relative density. The algorithm computes the deviatoric and volumetric creep strains by finding the value of the effective stress which satisfies the functional relationship, the effective stress function. Thus, one non-linear scalar equation is solved to find the unknown volumetric and deviatoric components of creep strain tensor. The tangent modulus is evaluated consistent with the integration algorithm. The application of the method to the simulation of hot isostatic pressing of metal powder is shown. The paper presents the solution of the verification problem and comparison with the experimental result. © 1998 John Wiley & Sons, Ltd.