A novel chemically amplified positive deep UV photoresist with significantly reduced sensitivity to environmental contamination

t-Boc protected Deep-UV transparent polymers with photoacid generators have been widely investigated as potential positive deep-UV resist systems. However, utility of these systems is seriously handicapped by environmental contaminants leading to an insoluble “surface skin” formation. Only with a specially controlled environment or by use of an “overcoat” material is the performance of these systems acceptable. We have investigated a series of t-Boc protected poly(styrene-maleimide) copolymers and poly(hydroxy styrene) polymers with onium-salts. Upon incorporation of a special class of organic additive, the surface effects inherent to these positive deep-UV systems are significantly reduced thereby avoiding any extraneous precaution of protecting the resist surface from a typical manufacturing environment. We evaluated these t-Boc polymer/onium-salt systems with different additives under a varied set of processing conditions. In addition, plausible structure-activity relationship of these additives in controlling the surface effects is presented.     

Effects of cyproterone acetate on reproductive functions in normal human males

The effects of cyproterone acetate (CA) on reproductive functions in normal human males were studied. 6 volunteers received 5 or 10 mg CA over a 20-week period. The treatment caused a gradual decrease in the number of spermatozoa and their motility, and an increase in the percentage of nonmotile, abnormal, and immature sperms. There was also a marked inhibition of sperm transport of motile sperm through cervical mucus, as determined by Kremer's test. Semen levels of acid phosphatase, sialic acid, and glycerylphosphorylcholine progressively decreased, though semen levels of fructose were not markedly altered. There were no marked changes in levels of SGOT, SGPT, serum alkaline phosphatase, blood urea, and hematocrit values. The possible mode of action of CA and its potential as a male contraceptive agent are discussed.     

Reduced lateral diffusion and reverse leakage in Be-implanted GaAs1−xPxdiodes

Lateral Zn diffusion under the Si₃N₄ mask encountered in standard red GaAs_0.6P_0.4 light emitting diodes can be eliminated in Be-implanted junctions. Typical reverse leakage current for implanted devices is ～ 5nA compared with ～ 250nA for Zn-diffused diodes.     

Free radical polymerization with long chain branching: continuous polymerization of vinyl acetate in t-butanol

Vinyl acetate was polymerized in a continuous stirred tank reactor (CSTR) at 60°C in t-butanol solution. Mean residence times ranged from 1.35 to 7.2 hr; steady state conversions ranged from 15 to 61%. Molecular weights $\text{M}$_n and $\text{M}$_w were measured and interpreted in terms of a kinetic model developed from batch studies and the state of local mixing in the reactor. Good macroscopic mixing was confirmed by tracer studies and measurements of conversion vs time during the start-up period and at steady state. The molecular weights obtained at high conversions agreed more closely with predictions based upon a locally segregated state than with those based on complete molecular mixing. However, calculations based on agitation and diffusion rates raised serious questions about the validity of the segregation model for this polymerization. Other factors, some chemical and some related to the agitation, may be important, but the problem of predicting molecular structure remains unresolved.     

Development of “tuned microwave absorbers” using U-type hexaferrite

The paper presents that microwave absorption is tunable with sample thickness over a frequency range if electromagnetic properties of the sample do not change with frequency in that range. The work summarizes the results of polycrystalline samples of two U-type hexaferrite series: Ba₄ (Co_1−5x P_2x)₂ Fe₃₆ O₆₀ (0.0 ? x ? 0.20 in step 0.05) and (Ba_1−3x La_2x)₄ Co₂ Fe₃₆ O₆₀ (0.10 ? x ? 0.25 in step 0.05) that have been prepared through solid state reaction route. The complex permittivity, permeability and microwave absorbing properties have been discussed in detail for X-band (8.2–12.4 GHz) frequencies. The results show that the substitution of Co²⁺ ion with P⁵⁺ ion and Ba²⁺ ion with La³⁺ ion in the U-type-hexaferrite provides the desired electromagnetic properties for a “tuned microwave absorber” in samples with x = 0.05 and 0.20 of first and 0.20 sample of second series. In these samples, the microwave absorption peak (of >98%) shifts linearly from lower to upper side of X-band with sample thickness. These materials can provide significant application for reduction of radar cross section (RCS) and in electromagnetic interference (EMI) shielding.     

Analyses for VVER-1000/320 reactor for spectrum of break sizes along with SBO

Severe accident analysis of a reactor is an important aspect for evaluation of source term. This in turn helps in emergency planning and severe accident management (SAM). Analyses have been carried out for VVER-1000 (V320) reactor following LOCA along with station blackout (SBO) to generate information on these aspects. Availability and unavailability of hydro-accumulators (HAs) are also considered for this study. Integral code ASTEC V1.3 (jointly developed by IRSN, France, and GRS, Germany) is used for analysing the transients. The predictions of different severe accident parameters like vessel rupture time, hydrogen and corium production and radioactivity release to containment have been compared for a spectrum of break sizes to provide information for probabilistic safety analysis (PSA) level-2 and severe accident management (SAM) guidelines.     

Low Cost Signal Reconstruction Based Testing of RF Components using Incoherent Undersampling

To meet the testing requirements of high speed components used in modern communication systems, in an efficient and cost effective manner, it is necessary to develop new device performance measurement techniques that are easily scalable to high frequencies. Traditional up/down conversion based transmitter testing architectures are sensitive to the linearity of the mixers and carrier phase noise in the receiver. Direct undersampling based test instrumentation can overcome the limitations imposed by mixers in up/down conversion. A major challenge in direct undersampling based test architecture is to achieve precise phase alignment between different components of the test setup. Such phase alignment of high frequency signals requires the use of expensive test instruments adding to the cost and complexity of the overall test system. To resolve this problem, an incoherent undersampling based test method is developed in this research that eliminates the need for precise phase synchronization between the RF test signal carrier, its amplitude-modulated envelope (generally necessary for measuring amplifier nonlinearity) and the reference sampling clock. A side-benefit, due to the use of signal undersampling, is that signal acquisition is achieved without the use of a Nyquist rate data converter. Multiple RF performance metrics are extracted without the use of a reference receiver. The accuracy of the proposed setup is compared against existing coherent sampling based test setups.     

Review paper on solar-powered air-conditioning through adsorption route

Solar-power based sorption refrigeration systems do not suffer from the problem of greenhouse gas emission and release of ozone layer depleting substances as in the case of conventional vapour compression refrigeration system. Absorption based systems are already commercially available while adsorption based systems are still in research and development stage. Progress and development of solar-powered adsorption cooling systems have been described in this paper. Factors preventing commercialization of this system have been discussed in detail. The state of the ongoing research, to make the system more efficient and cost effective, has been presented.