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Nonlinear optical processing of ambient natural light is highly desired for computational imaging and sensing. Strong optical nonlinear response under weak broadband incoherent light is essential for this purpose. By merging 2D transparent phototransistors (TPTs) with liquid crystal (LC) modulators, we create an optoelectronic neuron array that allows self-amplitude modulation of spatially incoherent light, achieving a large nonlinear contrast over a broad spectrum at orders-of-magnitude lower intensity than achievable in most optical nonlinear materials. We fabricated a 10,000-pixel array of optoelectronic neurons, and experimentally demonstrated an intelligent imaging system that instantly attenuates intense glares while retaining the weaker-intensity objects captured by a cellphone camera. This intelligent glare-reduction is important for various imaging applications, including autonomous driving, machine vision, and security cameras. The rapid nonlinear processing of incoherent broadband light might also find applications in optical computing, where nonlinear activation functions for ambient light conditions are highly sought.

Spatial manipulation of polarization, with the controlled synthesis of optical fields having non-uniform polarization distributions, presents a challenging task. Here, we demonstrate universal polarization transformers based on an engineered diffractive volume, which can synthesize a large set of arbitrarily-selected, complex-valued polarization scattering matrices between the polarization states at different positions within its input and output field-of-views (FOVs). This framework comprises 2D arrays of linear polarizers with diverse angles, which are positioned between isotropic diffractive layers, each containing tens of thousands of diffractive features with optimizable transmission coefficients. We demonstrate that, after its deep learning-based training, this diffractive polarization transformer could successfully implement Ni  No = 10,000 different spatially-encoded polarization scattering matrices with negligible error within a single diffractive volume, where Ni and No represent the number of pixels in the input and output FOVs, respectively. We experimentally validated this universal polarization transformation framework in the terahertz part of the spectrum by fabricating wire-grid polarizers and integrating them with 3D-printed diffractive layers to form a physical polarization transformer operating at λ = 0.75 mm wavelength. Through this set-up, we demonstrated an all-optical polarization permutation operation of spatially-varying polarization fields, and simultaneously implemented distinct spatially-encoded polarization scattering matrices between the input and output FOVs of a compact diffractive processor that axially spans 200×λ. This framework opens up new avenues for developing novel optical devices for universal polarization control, and may find various applications in, e.g., remote sensing, medical imaging, security, material inspection and machine vision. This article is protected by copyright. All rights reserved.

Terahertz waves offer advantages for nondestructive detection of hidden objects/defects in materials, as they can penetrate most optically-opaque materials. However, existing terahertz inspection systems face throughput and accuracy restrictions due to their limited imaging speed and resolution. Furthermore, machine-vision-based systems using large-pixel-count imaging encounter bottlenecks due to their data storage, transmission and processing requirements. Here, we report a diffractive sensor that rapidly detects hidden defects/objects within a 3D sample using a single-pixel terahertz detector, eliminating sample scanning or image formation/processing. Leveraging deep-learning-optimized diffractive layers, this diffractive sensor can all-optically probe the 3D structural information of samples by outputting a spectrum, directly indicating the presence/absence of hidden structures or defects. We experimentally validated this framework using a single-pixel terahertz time-domain spectroscopy set-up and 3D-printed diffractive layers, successfully detecting unknown hidden defects inside silicon samples. This technique is valuable for applications including security screening, biomedical sensing and industrial quality control.

The organophosphorous compound tabun is highly neurotoxic because of its irreversible inhibition on acetylcholinesterase (AChE). It is wildly used as a warfare agent in the military. In this work, the aging and reactivation mechanism of tabun-inhibited AChE were studied by using the quantum mechanical / molecular mechanical (QM/MM) method. Geometry optimization of the stationary points were performed at the B3LYP/6-31G(d) level. Single-point energies were computed at the B3LYP/6-311++G(d,p) level. On the basis of the QM/MM results, a conclusion that the C-O bond scission is caused by water attack on the ethoxy group in the aging mechanism can be drawn. The reactivation process initialed by the antidotes C[H.sub.2]N[O.sup.-] or HLO-7 consists of three elemental steps, the nucleophilic attack on the P atom by the antidote, the dephosphorylation process, and the decomposition of the antidote-tabun complex. The highest energy barriers of the aging reaction, C[H.sub.2]N[O.sup.-]-induced reactivation, and HLO-7-induced reactivation are 19.9, 20.0, and 14.8 kcal/mol (1 cal = 4.184 J), respectively. The relative lower overall energy barrier of HLO-7-induced reactivation compared with that of the aging reaction indicates that HLO-7 is able to reactivate tabun-inhibited AChE. In addition, whether a newly designed antidote is able to reactivate tabun-inhibited AChE can be examined by the inequation X < 19.9 kcal/mol, where X means the highest energy barrier of the reactivation reaction of the newly designed antidote. Key words: tabun, aging mechanism, reactivation mechanism, QM/MM method. Le tabun, un compose organophosphore, est extremement neurotoxique en raison de son inhibition irreversible de l'acetylcholinesterase (AChE). Il a ete utilise comme arme chimique. Dans ce travail, faisant appel a la methode de mecanique quantique / mecanique moleculaire (MQ/MM), on a etudie le vieillissement et le mecanisme de reactivation de de l'AChE inhibee par le tabun. On a effectue l'optimisation de la geometrie des points stationnaires au niveau B3LYP/6- 31G(d) de la theorie. On a calcule les energies des points uniques au niveau B3LYP/6-3111++G(d,p) de la theorie. Sur la base des resultats de methode de MQ/MM, il est possible d'arriver a une conclusion a l'effet que, dans le mecanisme de vieillissement, la scission de la liaison C-O est causee par l'attaque d'une molecule d'eau sur le groupe ethoxy. Le processus de reactivation initie par les antidotes C[H.sub.2]N[O.sup.-] ou HLO-7 comporte trois etapes elementaires, l'attaque nucleophile sur l'atome de phosphore par l'antidote, le processus de dephosphorylation et la decomposition du complexe antidote-tabun. La barriere d' energie la plus elevee de la reaction de vieillissement, la reactivation induite par le C[H.sub.2]N[O.sup.-] et la reactivation induite par le HLO-7 sont respectivement de 19,9, 20,0 et 14,8 kcal/mol (1 cal = 4.184 J). Le niveau relativement plus bas de l'energie d' activation globale pour la reactivation induite par le HLO-7 comparee a celle de la reaction de vieillissement indique que le HLO-7 peut reactiver l'AChE inhibee par le tabun. De plus, la possibilite qu'un nouvel antidote puisse reactiver l'AChE inhibee par le tabun a ete examinee par l'inequation X < 19,9 kcal/mol dans laquelle X correspond a la barriere d'energie la plus elevee de la reaction de reactivation du nouvel antidote mis au point. Mots-cles : tabun, mecanisme de vieillissement, mecanisme de reactivation, methode MQ/MM. [Traduit par la Redaction], Introduction Organophosphorus (OP) compounds, such as paraoxon, methamidophos, VX, and tabun, have been used as insecticides in modern agriculture or as chemical warfare agents in the military. The broad distribution [...]

Coiled amorphous carbon nanotube (CACNT) array was prepared by chemical vapor deposition method. The experimental results indicated that the length of as-prepared CACNT array was about 30 μm. The electromagnetic wave absorbing properties were studied through comparison among CACNTs, CACNT-La(NO 3 ) 3 , CACNT-(Fe, Co, Ni) and CACNT-reduced graphene oxide (RGO). The experimental results showed the maximum frequency bandwidth of CACNT-(Fe, Co, Ni) was 6.4 GHz below −5 dB and 2.3 GHz below −10 dB separately. Compared to the pure CACNTs, all the frequency bandwidth had been broaden after adding the modified agent. Meanwhile, the additive of rare earth ions La 3+ could effectively increase the maximum absorption peak (−17.94 dB at 8.96 GHz). [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiO 2 NPs) can cause health hazard after their release into the environment. Adsorption of natural organic matter and biomolecules on SiO 2 NPs alters their surface properties and cytotoxicity. In this study, SiO 2 NPs were treated by bovine serum albumin (BSA) and humic acid (HA) to study their effects on the integrity and fluidity of model cell membranes. Giant and small unilamellar vesicles (GUVs and SUVs) were prepared as model cell membranes in order to avoid the interference of cellular activities. The microscopic observation revealed that the BSA/HA treated (BSA-/HA-) SiO 2 NPs took more time to disrupt membrane than untreated-SiO 2 NPs, because BSA/HA adsorption covered the surface SiOH/SiO - groups and weakened the interaction between NPs and phospholipids. The deposition of SiO 2 NPs on membrane was monitored by a quartz crystal microbalance with dissipation (QCM-D). Untreated- and HA-SiO 2 NPs quickly disrupted the SUV layer on QCM-D sensor; BSA-SiO 2 NPs attached on the membranes but only caused slow vesicle disruption. Untreated-, BSA- and HA-SiO 2 NPs all caused the gelation of the positively-charged membrane, which was evaluated by the generalized polarity values. HA-SiO 2 NPs caused most serious gelation, and BSA-SiO 2 NPs caused the least. Our results demonstrate that the protein adsorption on SiO 2 NPs decreases the NP-induced membrane damage., (Copyright © 2016 Elsevier Ltd. All rights reserved.)