An auto-ranging photodiode preamplifier with 114 dB dynamic range

A low noise photodiode preamplifier integrated circuit with auto-ranging gain capability has been designed, fabricated, and tested. When connected to a 25 pF input capacitance, the four-channel device has an input referred noise below 0.5 fC, which is just 3 dB above the minimum kTC noise. The preamp chip is designed to handle a full-scale charge input of 210 pC and has a 114 dB dynamic range. The device achieves a linearity specification of 0.01% of input reading ±0.25 ppm of full scale with a sample period of 1 ms. The chip consumes 135 mW and is 5.8 mm×7.4 mm in size     

SimFlex: Statistical Sampling of Computer System Simulation

Timing-accurate full-system multiprocessor simulations can take years because of architecture and application complexity. Statistical sampling makes simulation-based studies feasibly by providing ten-thousand-fold reductions in simulation runtime and enabling thousand-way simulation parallelism.     

Modeling the combined effect of temperature and relative humidity on Escherichia coli O157:H7 on lettuce

The effect of relative humidity (RH) and temperature on the microbial behavior of Escherichia coli O157:H7 on lettuce was investigated. Experimental data obtained under different combined conditions of RH (60, 70, and 80%) and temperature (15, 25, and 35°C) were fitted into the Logistic model with delay to estimate specific growth rate (SGR) with high coefficients of determination (R ²s >0.98). The estimated SGR values were used to develop a Gamma-concept model. Then, several statistic characteristics were employed to verify the performance and reliability of the developed model, which demonstrated that the predictive model was not biased and had high accuracy in prediction. Besides, the analysis of relative importance of temperature and RH indicated that temperature is much more influential on the growth of E. coli O157:H7 on lettuce than the ambient RH changes.     

Fabrication of periodic square arrays by angle-resolved nanosphere lithography

We investigate the fabrication of periodic square arrays of solid gold islands by angle-resolved nanosphere lithography (ARNSL) in conjunction with thermal evaporation and etching. By varying θ (the tilt angle between the direction of gold deposition beam and the substrate surface normal) and ? (the substrate rotation angle about the beam axis), adjacent islands on a deposited hexagonal gold array will have a constant and periodic difference in height. Upon etching, this height bias will result in the shorter structures being removed to produce an array with a different symmetry from the original hexagonal symmetry of the parent mask. By depositing at three directions of ? = 0°, 120° and −120° with a constant θ = 20°, experimental results show that deposited two-dimensional gold periodic arrays will have a measurable difference in height between adjacent islands. Etching of the resulting patterns produced periodic near-square arrays with triangular nanostructures. Thus the combination of ARNSL and etching can allow selective periodic nanostructures to be removed, increasing the diversity of array symmetries available through nanosphere lithography.     

Effects of crystal and electronic structures of ANb2O6 (A=Ca,Sr, Ba) metaniobate compounds on their photocatalytic H2 evolution from pure water

Alkali-earth metaniobate compounds, ANb₂O₆ (A = Ca, Sr, Ba), were prepared by the conventional solid-state reaction route and their electronic band structures and photocatalytic activities were investigated. The prepared powders were characterized using X-ray diffraction (XRD), field-emission electron microscopy (FE-SEM), UV–vis diffuse reflectance spectroscopy, and fluorescence spectroscopy. It was found that the particle sizes (∼1 μm) and BET surface areas (∼1 m²/g) of the metaniobate compounds were nearly identical. From the electronic band structure calculations, however, the band-gap energies of these metaniobate compounds were found to be in the order of CaNb₂O₆ > SrNb₂O₆ > BaNb₂O₆. These calculated band-gap energies were consistent with those estimated from the UV–vis diffuse reflectance spectra. Moreover, the conduction-band edge (reduction potential) of SrNb₂O₆ calculated from the electronegativity data was higher than those of CaNb₂O₆ and BaNb₂O₆. The photoluminescence spectra revealed that CaNb₂O₆ exhibited a strong blue luminescence emission (at 300K), while no obvious emissions were observed in either SrNb₂O₆ or BaNb₂O₆. The luminescence behaviors of these metaniobate compounds and their band structure variations originating from their crystal structures play an important role in their photocatalytic activity for the evolution of H₂ from pure water. SrNb₂O₆, which has a higher conduction-band edge potential than the other compounds, exhibited higher photocatalytic activity.     

A High-Stress Liner Comprising Diamond-Like Carbon (DLC) for Strained p-Channel MOSFET

We report the integration of a new liner stressor comprising diamond-like carbon (DLC) film over a p-channel transistor. A high compressive stress of 6.5 GPa was achieved in a high-stress film with a thickness of 27 nm. A 74% enhancement in drive current was observed for the strained device with DLC liner as compared to a control device without DLC liner. Due to its much higher intrinsic stress value compared to conventional SiN films, a thinner DLC layer can induce comparable amount of stress in the transistor channel compared to a thicker SiN. The DLC material is a potential next-generation high-stress and low-permittivity liner stressor material suitable for application in transistors with aggressively scaled pitch dimensions.     

Fabrication of Thick Germanium-on-Insulator (GeOI) Substrates

Fabrication of germanium-on-insulator (GeOI) substrates with a 160-nm-thick Ge layer is reported. Such thick GeOI substrates were fabricated by thermal intermixing and subsequent condensation of epitaxially grown high-Ge- content SiGe on Si-on-insulator (SOI) substrates. Transmission electron microscopy revealed that the GeOI layer was single crystalline. The high-resolution rocking curve and reciprocal lattice map obtained from X-ray diffraction measurements showed a relaxed GeOI. This was further confirmed by micro-Raman measurements, where the Ge-Ge optical phonon peak shift represented a nearly strain-free Ge layer. Using this methodology, GeOI substrates with Ge layers 120–160 nm thick have been fabricated with thickness variations of less than 4 nm across 200 mm wafers.     

Comparison of Macrophage Immune Responses and Metabolic Reprogramming in Smooth and Rough Variant Infections of Mycobacterium mucogenicum

Mycobacterium mucogenicum (Mmuc), a rapidly growing nontuberculous mycobacterium (NTM), can infect humans (posttraumatic wound infections and catheter-related sepsis). Similar to other NTM species, Mmuc exhibits colony morphologies of rough (Mmuc-R) and smooth (Mmuc-S) types. Although there are several case reports on Mmuc infection, no experimental evidence supports that the R-type is more virulent. In addition, the immune response and metabolic reprogramming of Mmuc have not been studied on the basis of morphological characteristics. Thus, a standard ATCC Mmuc strain and two clinical strains were analyzed, and macrophages were generated from mouse bone marrow. Cytokines and cell death were measured by ELISA and FACS, respectively. Mitochondrial respiration and glycolytic changes were measured by XF seahorse. Higher numbers of intracellular bacteria were found in Mmuc-R-infected macrophages than in Mmuc-S-infected macrophages. Additionally, Mmuc-R induced higher levels of the cytokines TNF-α, IL-6, IL-12p40, and IL-10 and induced more BMDM necrotic death. Furthermore, our metabolic data showed marked glycolytic and respiratory differences between the control and each type of Mmuc infection, and changes in these parameters significantly promoted glucose metabolism, extracellular acidification, and oxygen consumption in BMDMs. In conclusion, at least in the strains we tested, Mmuc-R is more virulent, induces a stronger immune response, and shifts bioenergetic metabolism more extensively than the S-type. This study is the first to report differential immune responses and metabolic reprogramming after Mmuc infection and might provide a fundamental basis for additional studies on Mmuc pathogenesis.     

L-Type Ca2+ Channel Inhibition Rescues the LPS-Induced Neuroinflammatory Response and Impairments in Spatial Memory and Dendritic Spine Formation

Ca²⁺ signaling is implicated in the transition between microglial surveillance and activation. Several L-type Ca²⁺ channel blockers (CCBs) have been shown to ameliorate neuroinflammation by modulating microglial activity. In this study, we examined the effects of the L-type CCB felodipine on LPS-mediated proinflammatory responses. We found that felodipine treatment significantly diminished LPS-evoked proinflammatory cytokine levels in BV2 microglial cells in an L-type Ca²⁺ channel-dependent manner. In addition, felodipine leads to the inhibition of TLR4/AKT/STAT3 signaling in BV2 microglial cells. We further examined the effects of felodipine on LPS-stimulated neuroinflammation in vivo and found that daily administration (3 or 7 days, i.p.) significantly reduced LPS-mediated gliosis and COX-2 and IL-1β levels in C57BL/6 (wild-type) mice. Moreover, felodipine administration significantly reduced chronic neuroinflammation-induced spatial memory impairment, dendritic spine number, and microgliosis in C57BL/6 mice. Taken together, our results suggest that the L-type CCB felodipine could be repurposed for the treatment of neuroinflammation/cognitive function-associated diseases.