A 44-GHz-high IP3 InP HBT MMIC amplifier for low DC powermillimeter-wave receiver applications

This paper reports on what is believed to be the highest IP3/P_dc power linearity figure of merit achieved from a monolithic microwave integrated circuit (MMIC) amplifier at millimeter-wave frequencies. The 44 GHz amplifier is based on an InP heterojunction bipolar transistor (HBT) technology with f_T's and f_max's of 70 and 200 GHz, respectively. The 44-GHz amplifier design consists of four prematched 1×l0μm² four-finger (40-μm²) heterojunction bipolar transistor (HBT) cells combined in parallel using a compact λ/8 four-way microstrip combiner. Over a 44-50-GHz frequency band, the amplifier obtains a gain of 5.5-6 dB and a peak gain of 6.8-7.6 dB under optimum gain bias. At a low bias current of 48 mA and a total dc power of 120 mW, the amplifier obtains a peak IP3 of 34 dBm, which corresponds to an IP3/P_dc power ratio of 21:1, a factor of two better than previous state-of-the-art MMIC's reported in this frequency range. By employing a thin, lightly doped HBT collector epitaxy design tailored for lower voltage and higher IP3, a record IP3/P_dc, power ratio of 42.4:1 was also obtained and is believed to be the highest reported for an MMIC amplifier of any technology. The new high-linearity HBT's have strong implications for millimeter-wave receiver as well as low-voltage wireless applications     

Performance Evaluation of NL-BMD Precoding over Analog-Digital Hybrid Beamforming for High SHF Wide-Band Massive MIMO in 5G

Massive multiple-input multiple-output (MIMO) technology is a key enabler in 5G. A configuration combining analog beamforming and digital MIMO signal processing for multi-beam multiplexing, i.e. analog-digital hybrid beamforming, is one of the promising approaches of massive MIMO. With the configuration, we can mitigate the problems of complexity and power consumption, which are serious in higher super high frequency and extremely high frequency bands. In this paper, we evaluate the performance of nonlinear block multi-diagonalization (NL-BMD) precoding, an intermediate solution between the conventional linear precoder (LP) and nonlinear precoder (NLP), over an analog-digital hybrid beamforming constitution. Through numerical evaluation assuming indoor hotspot scenarios, it is clarified that, NL-BMD yields up to 18.8% improvement and 5.1 dB gain in average sum-rate spectral efficiency performance, compared with block diagonalization (BD), which is one of the typical schemes of conventional LP, while reducing the complexity to 1/2 of the conventional NLP. In addition, even under a dynamic fading condition, NL-BMD shows tolerance for channel transitions and still better performance than BD: NL-BMD suppresses performance loss in sum-rate spectral efficiency due to channel transitions to 18.3%, whereas BD shows over 20% loss.     

Implementation of the quantitative evaluation method of the tempering effect during heating and cooling processes in post-weld heat treatment

In order to evaluate the temper effect during the multiple post-weld heat treatment (PWHT) process, the thermal cycle tempering parameter (TCTP) proposed by the authors, which is derived by extending the Larson–Miller parameter (LMP) to a non-isothermal process, has been used to evaluate quantitatively the temper effect during heating and cooling processes in the process of PWHT. It has been clarified that the temper effect in the multiple PWHT process including long-time heating and cooling processes can be quantitatively evaluated by TCTP. On the basis of the present study, it might be possible to shorten the holding time of the heat treatment for multiple PWHT.     

A novel transmembrane semaphorin can bind c-src

The semaphorins/collapsins constitute a family of genes unified by the presence of a "semaphorin domain" which has been conserved through metazoan evolution. The semaphorin family comprises both secreted and transmembrane molecules and is thought to be made up of ligands for as yet unidentified receptors. The functions are not known, with the exception of those of sema III (also referred as sem D and collapsin 1), D-sema I, and D-sema II, which have been shown to be involved in axonal pathfinding. Here report the identification of a mouse semaphorin cDNA, termed Sema VIb. Although Sema VIb contains the extracellular semaphorin domain, it lacks the immunoglobulin domain or thrombospondin repeats which are present in other described vertebrate (but not invertebrate) transmembrane semaphorins. During development Sema VIb mRNA is expressed in subregions of the nervous system and is particularly prominent in muscle. In adulthood, Sema VIb mRNA is expressed ubiquitously. The cytoplasmic domain of Sema VIb contains several proline-rich potential SH3 domain binding sites. Using an in vitro binding assay, we show that Sema VIb binds specifically the SH3 domain of the protooncogene c-src. In transfected COS cells Sema VIb coimmunoprecipitates with c-src. These results, along with our evidence that Sema VIb can form dimers, suggests that the semaphorin family not only serves as ligands but may include members, especially those which are transmembrane, which serve as receptors, triggering intracellular signaling via an src-related cascade.     

Oxidation behavior of an Fe-38Ni-13Co-4.7Nb-1.5Ti-0.4Si superalloy at high temperature in Ar-H2O atmospheres

The oxidation of an Fe-38Ni-13Co-4.7Nb-1.5Ti-0.4Si superalloy (Incoloy 909 type alloy), was investigated at temperatures between 1000 K and 1400 K in Ar-(1, 10%)H₂0 atmosphere using metallographic, electron probe microanalysis, and X-ray diffraction techniques. The oxide scales consist of an external scale and an internal scale which has an intergranular scale (above 1200 K) and an intergranular scale. The oxide phases in each scale are identified as-Fe₂,O₃ (below 1200 K) or FeO (above 1300 K) and CoO · Fe₂O₃ and FeO · Nb₂O₅, respectively. The morphologies, the oxide phases and the oxidation rates do not depend on the partial pressure of H₂O in the range between one and ten percent in Ar gas. The rate constants for the intergranular-scale formation in this alloy are about one-tenth as large as those in Fe-36%Ni alloy reported previously. At all the temperatures the scales grow according to a parabolic rate law and the apparent activation energies for the processes are estimated.     

Hydroxyl radical-induced cross-linking of thymine and lysine: identification of the primary structure and mechanism

Hydroxyl radical-induced formation of a cross-link of thymine (Thy) and lysine (Lys) in the gamma-radiolysis of N2O-saturated aqueous solution was studied. A Thy-Lys cross-link (I) of the formal structure that OH radical and 4-carbon-centered Lys radical added respectively to C(5) and C(6) positions of Thy was isolated by a preparative HPLC and identified by a FAB-HRMS. The primary cross-link I was dehydrated by treatment with HCl at 120 degrees C to yield the secondary structure (II) possessing a C(5)-C(6) double bond in the Thy moiety: the latter structure II was reported previously (Dizdaroglu, M.; Gajewski, E. Cancer Res. 1989, 49, 3463-3467). A pulse radiolysis study with a redox titration method indicated that 4-carbon centered Lys radical intermediate was of neutral redox reactivity in contrast to reducing reactivity of 5-hydroxy-5,6-dihydrothymin-6-yl radical intermediate. The cross-link I could be formed by a conventional radical recombination mechanism, but not by an ionic recombination mechanism involving a redox reaction between the radical intermediates.     

Immunostimulatory effect of β-cryptoxanthin in vitro and in vivo

Beta-cryptoxanthin (β-Crp), a mono-hydroxylated β-carotene, is a major dietary provitamin A xanthophyll. The immunostimulatory effect of β-Crp was examined using human hybridoma HB4C5 cells and mouse primary lymphocytes in vitro and using mice in vivo. IgM production by the HB4C5 cells and both IgA and IgG productions by mouse primary lymphocytes from mesenteric lymph node and spleen were accelerated in vitro by the treatment of β-Crp in dose-dependent manners. Afterwards 6-week-old female BALB/c mice were administered with a low or high dose of β-Crp for 14 days, mesenteric lymph node and spleen were excised and the immunoglobulin production levels were evaluated using lymphocytes from mesenteric lymph node and spleen in vivo. Results exhibited that all of IgA, IgG, and IgM productions by lymphocytes from mesenteric lymph node were increased. Especially, the IgG production increased with statistically significant differences in both of the low and high dose groups against the control group. The immunostimulatory effect on splenocytes was also observed although not as clear as on lymphocytes from mesenteric lymph node. Overall results suggest that β-Crp may stimulate the humoral immunity in mammals. Hence, β-Crp might have a potentially significant impact on human health and on prevention of diseases.     

Effect of halogen additives on the stability of a-Si:H films deposited at a high-growth rate

We deposited a-Si : H,F films at a high-growth rate (15 Å/s) using a SiH₄ and SiF₄ gas mixture to examine the effect of halogen additives on the film stability against light exposure. Fluorinated a-Si : H films show a high conductivity over 5×10⁻⁵ S/cm and the Schottky cells made with fluorinated films exhibit an improved fill factor after light-soaking. SIMS measurements show an increased oxygen incorporation into the film at a SiF₄ flow of 5 sccm or larger, while virtually no increase is seen when a small SiF₄ flow rate of 1 sccm is used. This is presumably an indication that a small amount of SiF₄ can actually help improve the stability of a-Si : H films against light exposure.     

Metallurgical factors contributing to HAZ cracking susceptibility in cast alloy 718 welds and its improvement by cerium addition

A study was carried out to determine the effect of cerium addition on HAZ cracking susceptibility in cast alloy 718 welds. The cause of HAZ cracking was also investigated using commercial cast alloy 718 varying in grain size at three levels. The hot cracking test results for commercial cast alloy 718 indicated that the fine-grained alloy was less sensitive to HAZ cracking. Furthermore, cerium addition of up to 0.3 wt.% was found to have a beneficial effect in reducing HAZ cracking susceptibility. When cerium addition exceeds 0.3 wt%, HAZ cracking susceptibility increased further. The mechanism of HAZ cracking was found to be related to intergranular liquation caused by the eutectic melting of sulfur containing a laves cluster at the grain boundaries. The degree of grain boundary liquation in the fine-grained specimen was less than that of the coarse-grained specimen due to a decrease in the amount of laves cluster and sulfur segregation in it at the grain boundaries, which seems to be responsible for a reduction in hot cracking susceptibility in the fine-grained specimen. Microscopic observation suggested that the improved HAZ cracking susceptibility in cerium containing alloy could be attributed to a reduction in the amount of laves cluster and sulfur segregation in it at grain boundaries due to the grain size reduction and sulfur-scavenging effects of cerium.