Annealing Effects on the Band Alignment of ALD SiO2 on (Inx Ga1−x )2 O3 for x = 0.25–0.74

The band alignment of Atomic Layer Deposited SiO 2 on (In x Ga1−x) 2 O 3 at varying indium concentrations is reported before and after annealing at 450 °C and 600 °C to simulate potential processing steps during device fabrication and to determine the thermal stability of MOS structures in high-temperature applications. At all indium concentrations studied, the valence band offsets (VBO) showed a nearly constant decrease as a result of 450 °C annealing. The decrease in VBO was −0.35 eV for (In0.25Ga 0.75) 2 O 3 , −0.45 eV for (In0.42Ga 0.58) 2 O 3 , −0.40 eV for (In0.60Ga 0.40) 2 O 3 , and −0.35 eV (In0.74 Ga0.26) 2 O 3 for 450 °C annealing. After annealing at 600 °C, the band alignment remained stable, with <0.1 eV changes for all structures examined, compared to the offsets after the 450 °C anneal. The band offset shifts after annealing are likely due to changes in bonding at the heterointerface. Even after annealing up to 600 °C, the band alignment remains type I (nested gap) for all indium compositions of (In x Ga1−x ) 2 O 3 studied

Determining the Electron Storage Capacities of Black Carbon and Humic Acid Through Chemical Redox Titration

Pei C. Chiu, Ph.DCarbonaceous constituents in soil and sediment play critical roles in biotic and abiotic geochemical redox reactions. In particular, black carbon and humic substances supplying and receiving electrons are of key interest to researchers for their role in facilitating redox transformation of contaminants either directly (i.e., abiotically) or through microbial activity in soil and sediments. Black carbon (BC) is a category of solid carbonaceous materials formed by pyrolyzing biomass in an oxygen-deficient environment. As a commercially available black carbon that aims to promote soil fertility and microbial activity, it has been hypothesized that redox-active functional groups, such as quinone, are presented in the carbon matrix, and that they can exchange electrons with external bulk reactants. In this work, titanium(III) citrate, a colored, one electron transfer reducing agent, was evaluated as a titrant reducing a commercial black carbon and a standard humic acid. Through a series of batch reduction experiments and continuous monitoring of the UV-Vis absorbance at 400 nm, the measured electron storage capacity (ESC) of the black carbon was 4.3(±0.1) mmol electron/gram at pH 6.4, 4.1(±0.1) mmol electron/gram at pH 5, and 4.2(±0.4) mmol electron/gram BC at pH 7.5. In addition, to standardize titanium(III) citrate and to demonstrate that it has the capability to fully reduce quinone functional groups (the redox active component in black carbon and humic acid), 99% purity 1,4-benzoquinone was used to quantitatively titrate titanium(III) citrate stock solution to standardize the exact concentration of titanium(III) used prior to the ESC experiment. We show that the reduction of anthraquinone-2,6-disulfonate (AQDS) and benzoquinone (BQ) are kinetically facile processes; therefore, the slow kinetic of black carbon reduction is ascribed to slow intra-particle diffusion in black carbon particles. The ESC of humic acid was also estimated using similar titration applied on black carbon. Leonardite humic acid (LHA), one of the most studied standardized humic acid forms, was titrated using a similar approach. By observing the net change of absorbance at 250 nm upon mixing known amounts of titanium(III) citrate and LHA in solution, the electron transfer from titanium(III) citrate to humic acid can be studied. The ESC of Leonardite humic acid was determined to be 4.7(±0.4) mmol/g LHA at pH 6.4, 3.1(±0.3) mmol/g LHA at pH 5 and 4.1(±0.4) mmol/g LHA at pH 8. An approach of redox reduction of black carbon are hereby proposed, and upon acquirement of additional research progress, a protocol of black carbon titration can be developed and enables researchers to determine the electron storage capacity of black carbon synthesized using various materials and approaches in an efficient and affordable manner.Chemical Engineerin

Chemical methods for determining the electron storage capacity of black carbon

Electron storage capacity (ESC) is a new and important property that determines the capacity of a black carbon to mediate abiotic and microbial electron transfer reactions in natural and engineered systems. It is necessary to develop accurate and reproducible methods to measure black carbon's ESC in order to understand its redox behavior and to predict its capacity to support redox transformation of contaminants in subsurface environments. In this study, we developed chemical methods that employed combinations of reductants and oxidants of different redox potentials – Ti(III) citrate or dithionite as reductant, and ferricyanide or dissolved O2 as oxidant – to measure the ESC of a wood-derived biochar. Pore diffusion within biochar particles was rate-limiting and controlled the timescale for redox equilibrium and ESC measurements. • The new methods can handle sample mass on the order of a gram • Sample pretreatment (e.g., oxidation via aeration) is necessary to produce consistent results • For a given reductant-oxidant pair, colorimetric (or potentiometric) measurements gave constant and reproducible ESC Method name: Chemical method, Keywords: Black carbon, Biochar, Electron storage capacity, Electron accepting capacity, Electron donating capacity, Redox reversibility, Chemical oxidation/reductio

Demonstration of a SiC Protective Coating for Titanium Implants

To mitigate the corrosion of titanium implants and improve implant longevity, we investigated the capability to coat titanium implants with SiC and determined if the coating could remain intact after simulated implant placement. Titanium disks and titanium implants were coated with SiC using plasma-enhanced chemical vapor deposition (PECVD) and were examined for interface quality, chemical composition, and coating robustness. SiC-coated titanium implants were torqued into a Poly(methyl methacrylate) (PMMA) block to simulate clinical implant placement followed by energy dispersive spectroscopy to determine if the coating remained intact. After torquing, the atomic concentration of the detectable elements (silicon, carbon, oxygen, titanium, and aluminum) remained relatively unchanged, with the variation staying within the detection limits of the Energy Dispersive Spectroscopy (EDS) tool. In conclusion, plasma-enhanced chemical vapor deposited SiC was shown to conformably coat titanium implant surfaces and remain intact after torquing the coated implants into a material with a similar hardness to human bone mass

Annealing Effects on the Band Alignment of ALD SiO2 on (Inx Ga1−x )2 O3 for x = 0.25–0.74

The band alignment of Atomic Layer Deposited SiO 2 on (In x Ga1−x) 2 O 3 at varying indium concentrations is reported before and after annealing at 450 °C and 600 °C to simulate potential processing steps during device fabrication and to determine the thermal stability of MOS structures in high-temperature applications. At all indium concentrations studied, the valence band offsets (VBO) showed a nearly constant decrease as a result of 450 °C annealing. The decrease in VBO was −0.35 eV for (In0.25Ga 0.75) 2 O 3 , −0.45 eV for (In0.42Ga 0.58) 2 O 3 , −0.40 eV for (In0.60Ga 0.40) 2 O 3 , and −0.35 eV (In0.74 Ga0.26) 2 O 3 for 450 °C annealing. After annealing at 600 °C, the band alignment remained stable, with <0.1 eV changes for all structures examined, compared to the offsets after the 450 °C anneal. The band offset shifts after annealing are likely due to changes in bonding at the heterointerface. Even after annealing up to 600 °C, the band alignment remains type I (nested gap) for all indium compositions of (In x Ga1−x ) 2 O 3 studied

Annealing Effects on the Band Alignment of ALD SiO2 on (Inx Ga1−x )2 O3 for x = 0.25–0.74

The band alignment of Atomic Layer Deposited SiO 2 on (In x Ga1−x) 2 O 3 at varying indium concentrations is reported before and after annealing at 450 °C and 600 °C to simulate potential processing steps during device fabrication and to determine the thermal stability of MOS structures in high-temperature applications. At all indium concentrations studied, the valence band offsets (VBO) showed a nearly constant decrease as a result of 450 °C annealing. The decrease in VBO was −0.35 eV for (In0.25Ga 0.75) 2 O 3 , −0.45 eV for (In0.42Ga 0.58) 2 O 3 , −0.40 eV for (In0.60Ga 0.40) 2 O 3 , and −0.35 eV (In0.74 Ga0.26) 2 O 3 for 450 °C annealing. After annealing at 600 °C, the band alignment remained stable, with <0.1 eV changes for all structures examined, compared to the offsets after the 450 °C anneal. The band offset shifts after annealing are likely due to changes in bonding at the heterointerface. Even after annealing up to 600 °C, the band alignment remains type I (nested gap) for all indium compositions of (In x Ga1−x ) 2 O 3 studied

Association of immune cell composition with the risk factors and incidence of acute coronary syndrome

Abstract Background Although immune cells are involved in acute coronary syndrome (ACS), few studies have explored the association of incident ACS with the relative immune cell proportions. We aimed to investigate the association of immune cell proportions with the incidence and risk factors of ACS in the Dongfeng–Tongji cohort. Methods We conducted the analyses with 38,295 subjects from the first follow-up of the Dongfeng–Tongji cohort, including DNA methylation profiles for 1570 individuals. The proportions of immune cell types were observed from routine blood tests or estimated from DNA methylation profiles. For both observed and estimated immune cell proportions, we tested their associations with risk factors of ACS by multivariable linear regression models. In addition, the association of each immune cell proportion with incident ACS was assessed by the Cox regression model and conditional logistic regression model, respectively, adjusting for the risk factors of ACS. Findings The proportions of lymphocytes, monocytes, and neutrophils showed strong associations with sex, followed by diabetes. Moreover, sex and current smoking were the two factors with strongest association with the proportions of lymphocyte subtypes. The hazard ratio (HR) and 95% confidence interval (CI) of incident ACS per standard deviation (SD) increase in proportions of lymphocytes and neutrophils were 0.91 (0.85–0.96) and 1.10 (1.03–1.16), respectively. Furthermore, the OR (95% CI) of incident ACS per SD increase in proportions of NK cells, CD4+ T cells, and B cells were 0.88 (0.78–0.99), 1.15 (1.03–1.30), and 1.13 (1.00–1.26), respectively. Interpretation The proportions of immune cells were associated with several risk factors of ACS, including sex, diabetes, and current smoking. In addition, proportion of neutrophils had a risk effect, while proportion of lymphocytes had a protective effect on the incidence of ACS. The protective effect of lymphocytes was probably driven by NK cells

A Two-Electrode, Double-Pulsed Sensor Readout Circuit for Cardiac Troponin I Measurement

This paper presents a pulse-stimulus sensor readout circuit for use in cardiovascular disease examinations. The sensor is based on a gold nanoparticle plate with an antibody post-modification. The proposed system utilizes gated pulses to detect the biomarker Cardiac Troponin I in an ionic solution. The characteristic of the electrostatic double-layer capacitor generated by the analyte is related to the concentration of Cardiac Troponin I in the solvent. After sensing by the transistor, a current-to-frequency converter (I-to-F) and delay-line-based time-to-digital converter (TDC) convert the information into a series of digital codes for further analysis. The design is fabricated in a 0.18-μm standard CMOS process. The chip occupies an area of 0.92 mm 2 and consumes 125 μW. In the measurements, the proposed circuit achieved a 1.77 Hz/pg-mL sensitivity and 72.43 dB dynamic range