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We report the first study on a GaAs/GaAsSb core−shell (CS)-configured nanowire (NW)-based separate absorption, charge control, and multiplication region avalanche photodiode (APD) operating in the near-infrared (NIR) region. Heterostructure NWs consisted of GaAs and tunable band gap GaAs1−xSbx serving as the multiplication and absorption layers, respectively. A doping compensation of absorber material to boost material absorption, segment-wise annealing to suppress trap-assisted tunneling, and an intrinsic i-type and n-type combination of the hybrid axial core to suppress axial electric field are successfully adopted in this work to realize a room-temperature (RT) avalanche photodetection extending up to 1.3 μm. In an APD device operating at RT with a unity-gain responsivity of 0.2−0.25 A/W at ∼5 V, the peak gain of 160 @ 1064 nm and 18 V reverse bias, gain >50 @ 1.3 μm, are demonstrated. Thus, this work provides a foundation and prospects for exploiting greater freedom in NW photodiode design using hybrid axial and CS heterostructures. 

Abstract STEM technician and technologist careers can be accessible options for students; however, the historical devaluing of technical careers combined with a lack of awareness and familiarity with the specific options within this career cluster have resulted in a shortage of trained and prepared professionals. Grounded in social cognitive career theory, this survey study explores college students' knowledge of technical STEM careers, their high school career exploration experiences, and the relationship between science interest, career decision‐making, and technical career knowledge. Results from this survey indicate there is little to no familiarity with the majority of the STEM technician and technologist careers presented. However, results also show students are engaging in career exploration, and many are using more than one resource for exploration in their high school years. Implications for school counselors, teachers, family members, and community members are presented to specifically address the noted concerns. 

Quantum computing is on the cusp of reality with Noisy Intermediate-Scale Quantum (NISQ) machines currently under development and testing. Some of the most promising algorithms for these machines are variational algorithms that employ classical optimization coupled with quantum hardware to evaluate the quality of each candidate solution. Recent work used GRadient Descent Pulse Engineering (GRAPE) to translate quantum programs into highly optimized machine control pulses, resulting in a significant reduction in the execution time of programs. This is critical, as quantum machines can barely support the execution of short programs before failing. However, GRAPE suffers from high compilation latency, which is untenable in variational algorithms since compilation is interleaved with computation. We propose two strategies for partial compilation, exploiting the structure of variational circuits to pre-compile optimal pulses for specific blocks of gates. Our results indicate significant pulse speedups ranging from 1.5x-3x in typical benchmarks, with only a small fraction of the compilation latency of GRAPE. 

Sanitary sewer overflows (SSOs) are a common problem across the United States. An estimated number of 23 000–75 000 SSOs occurred in 2004, discharging between 11 and 38 billion liters of untreated wastewater to receiving waters. SSOs release many contaminants, including engineered nanomaterials (ENMs), to receiving water bodies. Measuring ENM concentrations in environmental samples remains a key challenge in environmental nanotechnology and requires the distinction between natural and engineered particles. This distinction between natural and engineered particles is often hampered by the similarities in the intrinsic properties of natural and engineered particles, such as particle size, composition, density, and surface chemistry, and by the limitations of the available nanometrology tools. To overcome these challenges, we applied a multi-method approach to measure the concentrations and properties of TiO 2 engineered particles ( e.g. , ENMs and pigments) including: 1) multi element-single particle-inductively coupled plasma-mass spectrometry (ME-SP-ICP-MS) to identify elemental associations and to determine elemental ratios in natural particles, 2) calculation of total elemental concentrations and ratios from total metal concentrations measured following total sample digestion to estimate engineered particle concentrations, and 3) transmission electron microscopy (TEM) to characterize engineered particle size and morphology. ME-SP-ICP-MS analysis revealed that natural TiO 2 particles are often associated with at least one of the following elements: Al, Fe, Ce, Si, La, Zr, Nb, Pb, Ba, Th, Ta, W and U, and that elemental ratios of Ti to these elements, except Pb, are typical of riverine particulates and the average crustal ratios. High TiO 2 engineered particle concentrations up to 100 μg L −1 were found in SSO-impacted surface waters. TEM analysis demonstrated the presence of regular-shape TiO 2 particles in SSO-impacted surface waters. This study provides a comprehensive approach for measuring TiO 2 engineered particle concentrations in surface waters. The quantitative data produced in this work can be used as input for modeling studies and pave the way for routine monitoring of ENMs in environmental systems, validation of ENM fate models, and more accurate ENM exposure and risk assessment.