Preservation of refrigerated meats with controlled atmospheres: Treatment and post-treatment effects of carbon dioxide on pork and beef

Whole pork loins were divided into roasts and subjected to air control and carbon dioxide enriched atmospheres at 1°C for up to 21 days. Quintuplicate samples of both control and carbon dioxide treated loins were transferred to air storage at 0,4,7, 14 and 21 days and further held for 0, 3(4), 7 and 10 days at 4°C. Microbiological counts were taken at all time permutations. The results indicated a strong inhibiting effect of the carbon dioxide atmosphere on microbial growth as well as a marked residual effect during post-treatment storage in air. Satisfactory colour and odour were maintained on the loins for extended storage times, with visual and olfactory deterioration preceding microbial spoilage. Beef round wedges were treated in a similar manner. Although bacterial spoilage inhibition was comparable, colour degeneration was rapid and severe, making the method unsuitable for treatment of finished beef cuts.     

PROPOSALS FOR THE EFFICIENT AND ECONOMICAL USE OF HOPS IN BREWING

The hop lupulin glands, which contain the essential oils and resin acids, can be separated effectively from the bulky and worthless bracts and residues in a mechanical process which avoids solvent contamination. The separation is accomplished in an air stream through a centrifugal sifter after the lupulin has been rubbed off in a disc pin mill. The separated lupulin can be broken open by grinding in a colloid mill and used to obtain a dry hop aroma in beers by an ‘instant’ process. The lupulin can be used to bitter beers either directly in the copper or in a pre-boiling process. It can also be used in an aqueous extraction process to yield, nearly quantatively, pure and separate extracts of the α- and β-acids. The α-acids can then be isomerized almost quantitatively and the β-acids can be oxidized to give a 50% yield of hulupones. The hop residues, when boiled with wort, give an approximately 50% utilization of the remaining α-acids. These isohumulones can then be enhanced by those obtained from the extracted α-acids and the bitterness can be supplemented by the hulupones obtained from the β-acids. Overall, this process is calculated to give a bitterness utilization equivalent to 87% calculated on the original α-acids.     

Effect of Al Composition and Gate Recess on Power Performance of AlGaN/GaN High-Electron Mobility Transistors

AlGaN/GaN high-electron mobility transistors with different Al compositions and barrier thicknesses were compared. The samples with higher Al composition and similar 2D electron gas density showed higher gate leakage, utilizing a slant field plate gate process. By applying a gate recess etch and a slant field plate gate process, gate leakage was improved to a similar level for all the devices, and the power density and PAE were much improved.     

亚太地区卫星正在启用新型业务

对于直接到户(DTH)业务的提供商和其它企业家来说,亚太地区存在着新的机会:高清晰度电视(HDTV)慢慢地进入了这一地区,蜂窝电话回传、因特网协议(IP)宽带和企业领域应用正在加速。所有这些让人明白,亚太地区的各种商业机会将在未来数年里稳步增长。泰国Shin卫星公司新宽带卫星iP     

光伏产业调整LED将席卷笔记本PC

全球对于太阳能的旺盛需求已导致用于生产太阳能电池的多晶硅出现严重短缺,促使光伏（PV）太阳能电池供应商调整业务结构和策略,以及寻找可替代的原材料。     

A combined field approach to scattering from infinite ellipticalcylinders using the method of ordered multiple interactions

The method of ordered multiple interactions (MOMI) is an iterative procedure which has been demonstrated to provide a rapidly convergent series for the problem of wave scattering from perfectly conducting surfaces rough in a single dimension. In this paper, we consider the extension of this technique to the problem of scattering from infinite elliptical cylinders. For an incident plane wave having its electric field polarized along the axis of the cylinder a combined field formulation of the scattering problem is found to provide a rapidly convergent MOMI series. The determination of an optimal combined field representation for the scattering problem in this case is also discussed. An extension of the MOMI method is necessary to properly treat the remaining polarization     

A 60-W high-beam-quality single-oscillator copper vapor laser

We report dramatic improvements (up to four times) in the generation of high-beam-quality (HBQ) output power from copper vapor lasers (CVLs) by using tailored HCl-H₂-Ne buffer gas mixtures. Up to 60 W of HBQ power was obtained from a 38-mm bore-diameter CVL at a pulse repetition frequency of 12 kHz and 50 W at 22 kHz. This improvement in power capability is attributable to the modification of the spatio-temporal gain characteristics of the laser when using the new buffer gas mixture     

Sensor allocation in diverse environments

Sensor coverage varies with location due to factors such as weather, terrain, and obstacles. If a field can be partitioned into zones of homogeneous sensing areas, then the area covered by a random deployment of sensors can be optimized by controlling the number of sensors deployed in each zone. This paper provides formulas to directly calculate the optimal sensor partition in runtime asymptotically equal to the number of zones; to determine the minimum sensor count required to achieve a specific coverage threshold; and to bound the maximum increase in coverage over a strategy oblivious to differences in sensing areas. Results show that this bound is no greater than 13% for a field with two zones. While the analytical solutions assume that each zone is covered independently, sensors are allowed to affect neighboring zones in simulations. Nevertheless, the simulation results support the optimality of the solutions.     

System characteristics of quasi-optical power amplifiers

Quasi-optical (QO) amplifiers have advanced to the point where they are competitive with other solid state and vacuum-based power amplifier technologies in the upper microwave and millimeter-wave bands. While still trailing in power-added efficiency, the QO amplifiers have advantages over traditional system architectures because of superior linearity, low noise, high spurious-free dynamic range, and added functionality (e.g., electronic beam steering). These advantages are stated in the present paper through a set of scaling laws that describe the behavior of fundamental amplifier properties versus the number n of elements in the QO array. It is known that the gain and power-added efficiency are scale independent, so that the output power scales as n ¹. Here we find that the white noise figure is scale independent and the 3rd order intercept point increases as n^3/2 . Hence, the spurious-free dynamic range (SFDR) should scale as n ¹.. This makes QO amplifiers attractive as "robust" low-noise amplifiers (LNAs) in traditional superheterodyne receivers. An analysis is carried out to predict the improvement in total SFDR of a superheterodyne receiver having a QO LNA at the front end     

A 44 GHz monolithic semiconductor dipole antenna

Monolithic semiconductor antennas integrated with a diode detector have been fabricated using silicon-on-sapphire technology. The performance of these antennas is analyzed on the basis of earlier theoretical work on imperfectly conducting/resistive cylindrical dipoles. The measured radiation patterns of semiconductor antennas are compared with those of the corresponding printed metal dipoles.