Nosocomial transmission of COVID-19 among immunocompromised hosts can have a serious impact on COVID-19 severity, underlying disease progression and SARS-CoV-2 transmission to other patients and healthcare workers within hospitals. We experienced a nosocomial outbreak of COVID-19 in the setting of a daycare unit for paediatric and young adult cancer patients. Between 9 and 18 November 2020, 473 individuals (181 patients, 247 caregivers/siblings and 45 staff members) were exposed to the index case, who was a nursing staff. Among them, three patients and four caregivers were infected. Two 5-year-old cancer patients with COVID-19 were not severely ill, but a 25-year-old cancer patient showed prolonged shedding of SARS-CoV-2 RNA for at least 12 weeks, which probably infected his mother at home approximately 7–8 weeks after the initial diagnosis. Except for this case, no secondary transmission was observed from the confirmed cases in either the hospital or the community. To conclude, in the day care setting of immunocompromised children and young adults, the rate of in-hospital transmission of SARS-CoV-2 was 1.6% when applying the stringent policy of infection prevention and control, including universal mask application and rapid and extensive contact investigation. Severely immunocompromised children/young adults with COVID-19 would have to be carefully managed after the mandatory isolation period while keeping the possibility of prolonged shedding of live virus in mind.

A new design method of an ultra-wideband circularly-polarized planar multiple-input-multiple-output (MIMO) antenna is presented in this paper. The proposed MIMO antenna consists of four unit cell antennas, being comprised of a microstrip feed line and a square slotted ground plane. In the proposed unit cell design, a circular stub is protruded from the ground plane strip for achieving circular polarization. The unit cell of the MIMO antenna is optimized by adjusting design parameters. The compact four-port MIMO antenna prototype is designed on the FR4 substrate with the overall dimensions of 45 × 45 × 1.6 mm3. The proposed four-port MIMO antenna design provides an impedance bandwidth (S11 < −10 dB) of 112% (3.1–11 GHz) and a 3 dB axial ratio bandwidth of 36% (4.8–6.9 GHz). The performance of the fabricated MIMO antenna shows good agreement between the EM simulation and measurement results.

Recent analyses of Lee et al. (2018, 2019) have confirmed that Galactic bulge consists of stellar populations originated from Milky Way globular clusters (MWGCs). Motivated by this, here we present the evolutionary population synthesis (EPS) for the Galactic bulge and early-type galaxies (ETGs) with the realistic treatment of individual variations in light elements observed in the MWGCs. We have utilized our model with GC-origin populations to explain the CN spread observed in ETGs, and the results show remarkable matches with the observations. We further employ our model to estimate the age of ETGs, which are considered as good analogs for the MW bulge. We find that, without the effect of our new treatments, EPS models will almost always underestimate the true age of ETGs. Our analysis indicates that the EPS with GC-origin populations is an essential constraint in determining the ETG formation epoch and is closely related to understanding the evolution of the Universe.

The self-assembly of known good dies (KGDs) on substrates using the liquid capillary method is shown to be a promising technology to achieve three-dimensional (3D) heterogeneous system integration and packaging. Firstly, the effects of the edge structures of self-assembled substrates and chips on alignment accuracies were investigated. When hydrophobic sidewalls with 10-µm-height steps were applied to both chips and assembly sites formed on substrates, the alignment accuracy within 1.0 µm was realized. The alignment accuracies were within 2.0 µm using either substrates or chips having 10-µm-height step structures with hydrophobic sidewalls. Self-assembly of 12-ch vertical-cavity surface-emitting lasers (VCSELs) with a long rectangle shape on glass substrates were also demonstrated. Separation of assembly sites into twelve areas enhanced the resultant force acting on the VCSEL short edge. The enhanced resultant force provided the high alignment accuracies within 2.0 μm. After the self-assembly of the VCSEL and the subsequent thermal compression, the chips successfully exhibited no degradation of their current–voltage (I–V) characteristics and appropriate 850-nm light emission. We demonstrated self-assembly and microbump bonding using non-conductive film (NCF)-covered dies with Cu/Sn microbumps for high-throughput and high-yield multichip-to-wafer 3D integration. The self-assembly of the NCF-covered dies provided high alignment accuracy within 1.1 μm on average. After the self-assembly of NCF-coved dies and thermal compression, microbump chains composed of 7396 bump joints were successfully obtained, resulting in good electrical properties of 32 mΩ/joint without any bridge shorts and failures. The variations of microbump joint resistance were maintained within 5% of the initial value after thermal cycle testing of even 1000 cycles.

To overcome various concerns due to scaling-down device size in future large-scale integration (LSI), it is indispensable to introduce a new concept of heterogeneous three-dimensional (3D) integration in which various kinds of device chips with different sizes, devices, and materials are vertically stacked. To achieve such heterogeneous 3D integration, the key technology of self-assembly and electrostatic (SAE) bonding has been developed. The heterogeneous 3D integration technology with the SAE bonding method has enabled 3D heterogeneous stacking of different types of chips such as the compound semiconductor device chip, photonic device chip, and spintronic device chip on complementary metal oxide semiconductor chips. A 3D image sensor with extremely fast processing speed and a 3D microprocessor with a self-test and self-repair function for future automatic driving vehicles are typical examples of heterogeneous 3D LSIs which we fabricated by the SAE bonding method.

We investigated the pressure dependence of the inductive coupled plasma (ICP) oxidation on the electrical characteristics of the thin oxide films. Activation energies and electron temperatures with different pressures were estimated. To demonstrate the pressure effect on the plasma oxide quality, simple N type metal-oxide-semiconductor (NMOS) transistors were fabricated and investigated in a few electrical properties. At higher pressure than 200mTorr, plasma oxide has a slightly higher on-current and a lower interfacial trap density. The on-current gain seems to be related to the field mobility increase and the lower defective interface to the electron temperature during oxidation.

Analytical electron microscopy (AEM) was used to examine the initial interfacial reaction layers between a eutectic Sn–3.5Ag solder and an electroless nickel-immersion gold-plated (ENIG) Cu substrate during reflow at 255 °C for 1 s. AEM confirmed that a thick upper (Au,Ni)Sn2 layer and a thin Ni3Sn4 layer had formed through the reaction between the solder and ENIG. The amorphous electroless Ni(P) plated layer transformed into two P-rich Ni layers. One is a crystallized P-rich Ni layer, and the other is an intermediate state P-rich Ni layer before the crystallization. The crystallized P-rich layer consisted of Ni2P and Ni12P5. A thin Ni2P layer had formed underneath the Ni3Sn4 layer and is believed to be a predecessor of the Ni2SnP ternary phase. A Ni12P5 phase was observed beneath the Ni2P thin layer. In addition, nanocrystalline Ni was found to coexist with the amorphous Ni(P) phase in the intermediate state P-rich Ni layer.

Oxidative modification of LDL is causally involved in the development of atherosclerosis and occurs in vivo in the blood as well as within the vascular wall. The present study attempted to explore whether polyphenolic flavonoids influence monocyte-endothelium interaction and lectin-like oxidised LDL receptor 1 (LOX-1) expression involved in the early development of atherosclerosis. The flavones luteolin and apigenin inhibited THP-1 cell adhesion onto oxidised LDL-activated human umbilical vein endothelial cells (HUVEC), while the flavanols of ( − )epigallocatechin gallate and (+)catechin, the flavonols of quercetin and rutin, and the flavanones of naringin, naringenin, hesperidin and hesperetin did not have such effects. Consistently, Western blot analysis revealed that the flavones at 25 μm dramatically and significantly abolished HUVEC expression of vascular cell adhesion molecule-1 and E-selectin evidently enhanced by oxidised LDL; these inhibitory effects were exerted by drastically down regulating mRNA levels of these cell adhesion molecules. In addition, quercetin and luteolin significantly attenuated expression of LOX-1 protein up regulated in oxidised LDL-activated HUVEC with a fall in transcriptional mRNA levels of LOX-1. In addition, quercetin and luteolin clearly blunted oxidised LDL uptake by HUVEC treated with oxidised LDL. The results demonstrate that the flavones luteolin and apigenin as well as quercetin were effective in the different initial steps of atherosclerosis process by inhibiting oxidised LDL-induced endothelial monocyte adhesion and/or oxidised LDL uptake. Therefore, certain flavonoids qualify as anti-atherogenic agents in LDL systems, which may have implications for strategies attenuating endothelial dysfunction-related atherosclerosis.

High plasma level of cholesterol is a well-known risk factor for atherosclerotic diseases. Oxidized LDL induces cellular and nuclear damage that leads to apoptotic cell death. We tested the hypothesis that flavonoids may function as antioxidants with regard to LDL incubated with 5 μm-Cu2+ alone or in combination with human umbilical vein endothelial cells (HUVEC). Cytotoxicity and formation of thiobarbituric acid-reactive substances induced by Cu2+-oxidized LDL were examined in the presence of various subtypes of flavonoid. Flavanols, flavonols and flavanones at a non-toxic dose of 50 μm markedly inhibited LDL oxidation by inhibiting the formation of peroxidative products. In contrast, the flavones luteolin and apigenin had no such effect, with >30 % of cells killed after exposure to 0.1 mg LDL/ml. Protective flavonoids, especially (−)-epigallocatechin gallate, quercetin, rutin and hesperetin, inhibited HUVEC nuclear condensation and fragmentation induced by Cu2+-oxidized LDL. In addition, immunochemical staining and Western blot analysis revealed that anti-apoptotic Bcl-2 expression was enhanced following treatment with these protective flavonoids. However, Bax expression and caspase-3 cleavage stimulated by 18 h incubation with oxidized LDL were reduced following treatment with these protective flavonoids. The down-regulation of Bcl-2 and up-regulation of caspase-3 activation were reversed by the cytoprotective flavonoids, (−)-epigallocatechin gallate, quercetin and hesperetin, at ≥10 μm. These results suggest that flavonoids may differentially prevent Cu2+-oxidized LDL-induced apoptosis and promote cell survival as potent antioxidants. Survival potentials of certain flavonoids against cytotoxic oxidized LDL appeared to stem from their disparate chemical structure. Furthermore, dietary flavonoids may have therapeutic potential for protecting the endothelium from oxidative stress and oxidized LDL-triggered atherogenesis.

The Far-ultraviolet IMaging Spectrograph (FIMS) is a small spectrograph optimized for the observations of diffuse hot interstellar medium in far-ultraviolet wavebands (900–1150Å and 1335–1750Å). The instrument is expected to be sensitive to emission line fluxes an order of magnitude fainter than any previous missions. FIMS is currently under development and is scheduled for launch in 2002.

We synthesized novel cross-linkable fluorinated copoly(arylene ether sulfide)s for optical waveguide applications, which have high thermal stability, high optical transparency in the infrared communication region, and much smaller birefringence than other thermally stable fluorinated polyimides. The refractive index of the material can be easily controlled from 1.515 to 1.587 by changing the copolymer composition in the materials. The birefringence of the cured polymers were 0.0031∼0.0039 at the wavelength of 1.55 μm. This is much lower than those of fluorinated polyimides for optical waveguides. The refractive index of fluorinated poly(arylene ether sulfide) (FPAESI) after being stored at 100 °C for 1000 hr remains almost constant demonstrating the thermal stability. The propagation loss of the channel waveguides fabricated using reactive ion etching was less than 0.4 dB/cm at the wavelength of 1.55 μm.

The surface properties of polyimide can be changed without altering the bulk properties. The surface layer (around 200 Å) of fully cured PMDA-ODA polyimide is chemically modified to polyamic acid which is subsequently imidized at 230 °C for 30 min to give an unordered polyimide surface. This unordered layer seems amorphous since it swells well in NMP. The modified surfaces are analyzed by surface sensitive techniques such as contact angle measurement, XPS, ISS, and external reflectance infrared (ERIR) spectroscopy. Adhesion of polyimides and chromium on the amorphous polyimides is greatly enhanced. Interdiffusion and subsequent mechanical interlocking are the major contributions to the polyimide-polyimide adhesion.