This article presents a capacitively coupled voltage-controlled oscillator (VCO)-based sensor readout featuring a hybrid phase-locked loop (PLL)-ΔΣ modulator structure. It leverages phase-locking and phase-frequency detector (PFD) array to concurrently perform quantization and dynamic element matching (DEM), much-reducing hardware/power compared with the existing VCO-based readouts' counting scheme. A low-cost in-cell data-weighted averaging (DWA) scheme is presented to enable a highly linear tri-level digital-to-analog converter (DAC). Fabricated in 40-nm CMOS, the prototype readout achieves 78-dB SNDR in 10-kHz bandwidth, consuming 4.68 μW and 0.025-mm2 active area. With 172-dB Schreier figure of merit, its efficiency advances the state-of-the-art VCO-based readouts by 50×.
This article presents a second-order noise-shaping (NS) successive approximation register (SAR) analog-to-digital converter (ADC) with a process, voltage, and temperature (PVT)-robust closed-loop dynamic amplifier. The proposed closed-loop dynamic amplifier combines the merits of closed-loop architecture and dynamic operation, realizing robustness, high accuracy, and high energy-efficiency simultaneously. It is embedded in the loop filter of an NS SAR design, enabling the first fully dynamic NS-SAR ADC that realizes sharp noise transfer function (NTF) while not requiring any gain calibration. Fabricated in 40-nm CMOS technology, the prototype ADC achieves an SNDR of 83.8 dB over a bandwidth of 625 kHz while consuming only 107 μW. It results in an SNDR-based Schreier figure-of-merit (FoM) of 181.5 dB.
As any analog-to-digital converter (ADC) with a front-end sample-and-hold (S/H) circuit, successive approximation register (SAR) ADC suffers from a fundamental signal-to-noise ratio (SNR) challenge: its sampling kT/C noise. To satisfy the SNR requirement, the input capacitor size has to be sufficiently large, leading to a great burden for the design of the ADC input driver and reference buffer. This article presents an SAR ADC with a kT/C noise-cancellation technique. It enables the substantial reduction of ADC input capacitor size but without the large kT/C noise penalty. It greatly relaxes the requirement for ADC input driver and reference buffer. Built in 40-nm CMOS, a prototype 13-bit ADC has only 240-fF input capacitance and occupies a small area of 0.005 mm2. Operating at 40 MS/s, it achieves a 69-dB signal-to-noise-and-distortion ratio (SNDR) across the Nyquist frequency band while consuming 591 μW of power.
2D/1D graphitic carbon nitride hybridized with titanate nanotubes (g-C3N4/TNTs) was prepared through a hydrothermal reaction–calcination method. The photocatalyst exhibited high degradation efficiency for sulfamethazine (SMT) through photocatalysis under simulated solar light. The optimized material was composed of anatase, rutile, titanate and g-C3N4 crystalline phases. In situ transformation of titanate to anatase and rutile with specific content proportion (∼80:20, P25-type composition) leaded to formation of nanoscale “hot spots” at rutile–anatase–titanate interfaces, and then subsequent charge transfer occurred. Large specific surface area of TNTs as skeleton resulted in high-efficient interface reaction, while heterojunction with g-C3N4 further extended the adsorption to visible light region and retarded electron-hole pairs recombination. Density functional theory (DFT) calculation indicated the SMT sites with high Fukui nucleophilic (f-) index prefered to be attacked by radacils. Reduced toxicity of SMT degradation intermediates, good reusability and stability of g-C3N4/TNTs all suggested the great application potential in practical water treatment area.
Chronic obstructive pulmonary disease (COPD) is a frequent diagnosis in older individuals and contributor to global morbidity and mortality. Given the link between lung disease and aging, we need to understand how molecular indicators of aging relate to lung function and disease. Using data from the population-based KORA (Cooperative Health Research in the Region of Augsburg) surveys, we associated baseline epigenetic (DNA methylation) age acceleration with incident COPD and lung function. Models were adjusted for age, sex, smoking, height, weight, and baseline lung disease as appropriate. Associations were replicated in the Normative Aging Study. Of 770 KORA participants, 131 developed incident COPD over 7 years. Baseline accelerated epigenetic aging was significantly associated with incident COPD. The change in age acceleration (follow-up - baseline) was more strongly associated with COPD than baseline aging alone. The association between the change in age acceleration between baseline and follow-up and incident COPD replicated in the Normative Aging Study. Associations with spirometric lung function parameters were weaker than those with COPD, but a meta-analysis of both cohorts provide suggestive evidence of associations. Accelerated epigenetic aging, both baseline measures and changes over time, may be a risk factor for COPD and reduced lung function.
Covalent organic frameworks (COFs) have recently been demonstrated to have great application potentials in water treatment. Their photocatalytic performance towards bacterial disinfection and organic pollutant degradation yet has seldom been investigated. In this study, AgI modified COFs (using 2,5-diaminopyridine and 1,3,5-triformylphloroglucinol as precursors) (COF-PD/AgI) were fabricated and their applications to photocatalytically disinfect bacteria and degrade organic pollutants were investigated. COF-PD/AgI exhibited effective photocatalytic performance towards Escherichia coli disinfection and organic pollutant (Rhodamine B and acetaminophen) degradation. SEM images were employed to investigate cell disinfection process, while theoretical density functional theory (DFT) calculation and intermediates determination were used to elucidate organic pollutant degradation processes. Scavenger experiments, ESR spectra and chemical probes experiments confirmed O2−, h+ and OH played important roles in the photocatalytic process. The formation of dual-band Z-scheme heterojunction improved photocatalytic performance. COF-PD/AgI remained high photocatalytic activity in the four consecutive cycles and could serve as a promising photocatalyst for water purification.
Snowpack stores cold-season precipitation to meet warm-season water demand. Climate change threatens to disturb this balance by altering the fraction of precipitation falling as snow and the timing of snowmelt, which may have profound effects on food production in basins where irrigated agriculture relies heavily on snowmelt runoff. Here, we analyse global patterns of snowmelt and agricultural water uses to identify regions and crops that are most dependent on snowmelt water resources. We find hotspots primarily in high-mountain Asia (the Tibetan Plateau), Central Asia, western Russia, western US and the southern Andes. Using projections of sub-annual runoff under warming scenarios, we identify the basins most at risk from changing snowmelt patterns, where up to 40% of irrigation demand must be met by new alternative water supplies under a 4 °C warming scenario. Our results highlight basins and crops where adaptation of water management and agricultural systems may be especially critical in a changing climate.