Effects of higher order nonlinearities on second-order frequency mixing

Equations are presented here which describe second-order nonlinear frequency mixing under conditions where third-order non-linearities significantly alter the phase-matching relations. The coupled amplitude and phase equations illustrate that additional phase mismatch of the second-order process can be expected due to third-order nonlinearities. These nonlinearities include refractive index changes for a wave at one frequency due to waves at other frequencies. Growth of off-axis weak waves (small scale self-focusing) is described in terms of four-wave mixing in the presence of the second-order frequency mixing. It is shown that in at least some cases growth of off-axis waves is enhanced by second-order frequency mixing.     

Dermatitis-inducing furanocoumarins on leaf surfaces of eight species of Rutaceous and Umbelliferous plants

Eight species of Rutaceae or Umbelliferae, known to cause or suspected of causing photophytodermatitis, had the linear furanocoumarins psoralen, bergapten, and xanthotoxin on their leaf surfaces, in concentrations varying from 0.014 to 1800 /gmg/g fresh weight, equivalent to 0.17–56% of the total leaf concentration. The higher percentage generally observed for spring leaves compared to autumn leaves suggests a higher rate of transfer of these furanocoumarins to the surface in the younger leaves. Among the plants studied,Ruta graveolens had the highest surface concentrations of all three furanocoumarins. The relatively high effectiveness in causing dermatitis of some species with low surface concentrations may be explained by a more effective mechanism of transfer of the furanocoumarins to the skin. A role in the defense of the plant is suggested by their accumulation on the plant surface.A paper based on the work reported here was presented at the Groupe Polyphénols conference, Brock University, St. Catharines, Ontario, Canada, August 19–19, 1988.     

CROSS-FLOW FILTRATION OF FUNGAL SUSPENSION WITH REVERSED-FLOW CLEANING

The separation of fungal suspension Trichoderma reesei was studied by using cross-flow filtration(CFF)with re-versed-flow cleaning(RFC)technique.The advantage of this technique is demonstrated in comparison with other filtra-tion techniques.The filtration rate is influenced by different frequencies of RFC.For optimum combination of CFF andRFC,both experimental and theoretical considerations are necessary and are discussed.An expression has been derivedfor the optimum filtration time needed to maximize the flux for a given RFC period assuming that the filtration stage canbe approximated by Ruth’s equation.The practical usefulness of this calculation is demonstrated on a batch thickening op-eration.     

Plasma Lipid Peroxidation and Vitamin E Supplementation during High Intakes of Fish-Oil Fatty Acids

High intakes of fish oil concentrates (15g/day MaxEPA) resulted in increased TBARS in plasma after 2 weeks irrespective of the vitamin E intake and plasma content. After 4 weeks TBARS values returned to normal despite continued MaxEPA supplementation and different vitamin E levels. Fish oil supplements resulted in increased whole-blood aggregation and higher plasma glucose concentrations which did not occur when extra vitamin E was given. No significant differences in plasma cholesterol levels were observed.     

A Patterned 3D Silicon Anode Fabricated by Electrodeposition on a Virus‐Structured Current Collector

Electrochemical methods were developed for the deposition of nanosilicon onto a 3D virus‐structured nickel current collector. This nickel current collector is composed of self‐assembled nanowire‐like rods of genetically modified tobacco mosaic virus (TMV1cys), chemically coated in nickel to create a complex high surface area conductive substrate. The electrochemically depo­sited 3D silicon anodes demonstrate outstanding rate performance, cycling stability, and rate capability. Electrodeposition thus provides a unique means of fabricating silicon anode materials on complex substrates at low cost.     

A 6.5-J flashlamp-pumped Ti:Al2O3 laser

A flashlamp-pumped Ti:A₂O₃ oscillator has delivered 6.5 J per pulse at 800 nm under long-pulse extraction conditions. The device was designed for efficient short-pulse (2-3 ns) amplification to the multijoule energy level. To date, a peak stored energy in excess of 5 J has been obtained and is available for short-pulse extraction studies. The design and resulting characterization of this laser are discussed. The results show that the energy available for short-pulse extraction is limited by the flashlamp pumping time     

Methodology for Small-Signal Model Extraction of AlGaN HEMTs

Both large- and small-periphery AlGaN high- electron mobility transistors (HEMTs) will find applications in microwave systems from 2 to 40 GHz because of their superior power handling capability. A self-consistent approach is presented for the linear model's parameter extraction from measured S-parameters. The model for parasitics is selected to reflect loading from both the probe pads and the interconnect regions, including the air bridges. The objective is to accurately extract intrinsic model parameters as the device periphery is increased from 50 mum to 1 mm and to isolate the effects of device layouts, including air bridging the source regions. To accurately extract the shunt and series parasitics, the device must be represented in its ON- and OFF-states determined by the gate and drain bias. The intrinsic device capacitances are not negligible in the forward and beyond-pinchoff reverse bias states at zero drain bias and must be accounted for. With these corrections to the measured S-parameters, consistent results for the intrinsic device parameters are obtained with both small- and large-periphery AlGaN HEMTs.     

Effect of exercise and pre-slaughter stress on pork muscle characteristics

The effects of exercise, stress and chill temperature on pork muscle characteristics were studied in a 3 × 2 × 2 factorial experiment in which treatments were assigned to blocks made up of six pigs of the same sex from the same litter. Pigs were fed a corn-soybean meal diet with the two littermate pigs on each treatment fed together. Treatments were (1) a control group receiving no exercise and fed in an 8 m(2) pen; (2) a treatment group fed in an 8 m(2) pen and driven 1·6 km/day for 100 days prior to slaughter; and (3) a treatment group fed in pens with 40 m(2) floor space with feeders placed 5 m from their waterers. When the animals averaged approximately 105 kg in weight, one animal from each pair treated alike was subjected to standardized stress. After slaughter, one side was chilled at 2-3°C and the other at 13-15°C for 24 h. Both sides were then chilled at 2-3°C for an additional 24 h. Exercise did not affect average daily gain (ADG), feed efficiency, yield of total wholesale cuts, muscle pH, protein solubility, fiber diameter and sarcomere length of the Longissimus dorsi (LD) and Quadriceps femoris (QF) muscles or the tenderness of the QF muscle. Exercise decreased backfat thickness and the subjective tenderness of the LD muscle. The effects of stress on the characteristics evaluated were consistent with those that have been previously reported. Chilling temperature and interactions involving chilling temperature did not affect any of the characteristics studied. No exercise × stress interactions were observed. Protein solubility values indicated that pale, soft exudative (PSE) muscle was not a factor in any of the treatments. It was concluded that exercise will produce leaner carcasses but less tender muscle and that exercise will not counteract the effects of pre-slaughter stress.     

Power rail logic: a low power logic style for digital GaAs circuits

This paper describes a new logic style called Power Rail Logic (PRL), which is compatible with direct-coupled FET logic (DCFL) circuits. Multiplexors, latches, flip-flops, and exclusive-OR gates can be built using this logic style. Compared to DCFL, PRL uses fewer transistors, has larger noise margins, and up to 40% lower power-delay products. A test chip containing 32-b barrel shifters designed in DCFL and in PRL was successfully fabricated and tested. Test results are given for both circuits     

Current Variability in Si Nanowire MOSFETs Due to Random Dopants in the Source/Drain Regions: A Fully 3-D NEGF Simulation Study

In this paper, we study the impact of random discrete dopants in the source/drain (S/D) leads on the current variability of a gate-all-around Si nanowire transistor. Due to the strong inhomogeneities of the self-consistent electrostatic potential, a fully 3D real-space nonequilibrium Green's function (NEGF) formalism is used. N-channel transistors with random discrete donors in the S/D regions varying in both numbers and locations have been simulated. We have studied the impact of quasi-bound (QB) states and transmission resonances associated with the attractive potential of the donors on the screening of the impurities and on the current transport. The convergence of the coupled 3D Poisson-NEGF equations for narrow wires with discrete dopants is cumbersome due to the quasi-discrete nature of QB states and resonances of the attractive impurity potential. We present a robust solution strategy dealing with the convergence challenges. Large variations in the on-current and modest variations in the subthreshold slope are observed in the I _D-V _G characteristics when comparing devices with microscopically different discrete dopant configurations. We have also estimated the access resistance associated with the random dopant regions in the source and the drain leads and find very good agreement with the resistance estimated from the bulk silicon mobility at the same doping concentration.