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Structured optical materials create new computing paradigms using photons, with transformative impact on various fields, including machine learning, computer vision, imaging, telecommunications, and sensing. This Perspective sheds light on the potential of free-space optical systems based on engineered surfaces for advancing optical computing. Manipulating light in unprecedented ways, emerging structured surfaces enable all-optical implementation of various mathematical functions and machine learning tasks. Diffractive networks, in particular, bring deep-learning principles into the design and operation of free-space optical systems to create new functionalities. Metasurfaces consisting of deeply subwavelength units are achieving exotic optical responses that provide independent control over different properties of light and can bring major advances in computational throughput and data-transfer bandwidth of free-space optical processors. Unlike integrated photonics-based optoelectronic systems that demand preprocessed inputs, free-space optical processors have direct access to all the optical degrees of freedom that carry information about an input scene/object without needing digital recovery or preprocessing of information. To realize the full potential of free-space optical computing architectures, diffractive surfaces and metasurfaces need to advance symbiotically and co-evolve in their designs, 3D fabrication/integration, cascadability, and computing accuracy to serve the needs of next-generation machine vision, computational imaging, mathematical computing, and telecommunication technologies. Optical computing via free-space-based structured optical materials allows to access optical information without the need for preprocessing or optoelectronic conversion. In this Perspective, the authors describe opportunities and challenges in their use for optical computing, information processing, computational imaging and sensing. [ABSTRACT FROM AUTHOR]

Plasmonic photocatalysis has recently attracted much attention in enhancing the solar-to-chemical conversion efficiency (SCCE) owing to localized surface plasmon resonance (LSPR), whose energy can be synthetically varied from the ultraviolet through the visible to the near-infrared region. This wide variability is inaccessible by traditional semiconductor photocatalysts. However, for all-metal plasmonic photocatalysts, the photogenerated hot charge carriers have an ultrashort lifetime because of their rapid recombination. For most metal–semiconductor hybrid plasmonic photocatalysts, a large portion of plasmonic hot charge carriers is lost during transfer from the metal to the semiconductor because of the Schottky barrier formed at the metal–semiconductor interface. As a result, both types of plasmonic photocatalysts exhibit limited SCCEs. To overcome the aforementioned shortcomings, a new type of plasmonic photocatalyst, the Schottky-barrier-free plasmonic photocatalyst, has been proposed recently. This type of plasmonic photocatalyst not only possesses LSPR to generate abundant hot charge carriers, but is also Schottky-barrier-free so that the hot charge carriers can be utilized more sufficiently to drive redox reactions. In this perspective, we first discuss the different types of plasmonic photocatalysts using representative examples, then introduce Schottky-barrier-free plasmonic photocatalysts, and finally provide the major challenges and remaining questions of this new type of plasmonic photocatalyst. We believe this perspective will offer insight into the further development of plasmonic photocatalysis and the improvement of its SCCEs. [ABSTRACT FROM AUTHOR]

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 [...]

Single-walled carbon nanotubes (SWCNTs) were prepared by a modified arc discharge furnace using 500 Torr helium as buffer gas at 600 °C. The effect of the catalyst type on the production of SWCNTs was studied by transmission electron microscopy, X-ray diffraction and Raman spectroscopy. The experimental results indicated that the catalyst composition plays an important role in the production rate and purity of the SWCNTs product. Fe-Ni-Mg and Co-Ni powder catalysts demonstrated excellent catalytic effect at a catalyst content of 3 wt%. The soot production rate was up to 15 g/hr and the mean diameter of SWCNTs was about 1.3 nm. [ABSTRACT FROM AUTHOR]

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]

Quantum dots (QDs) have attracted broad attention due to their special optical properties and promising prospect in medical and biological applications. However, the process of QDs on cell membrane is worth further investigations because such process may lead to harmful effects on organisms and also important for QD application. In this study, adhesion of amino- and carboxyl-coated CdTe QDs (A-QDs and C-QDs) on cell membrane and the subsequent internalization are studied using a series of endocytosis-free model membranes, including giant and small unilamellar vesicles, supported lipid bilayers and giant plasma membrane vesicles (GPMVs). The adhered QD amounts on model membranes are quantified by a quartz crystal microbalance. The CdTe QD adhesion on model membranes is governed by electrostatic forces. Positively charged A-QDs adhere on GPMV surface and passively penetrate the plasma membrane via endocytosis-free mechanism, but negatively charged C-QDs cannot. Rat basophilic leukemia (RBL-2H3) cells are exposed to CdTe QDs to monitor the QD internalization process. Both A- and C-QDs are internalized by RBL-2H3 cells mainly via endocytosis. CdTe QDs do not accumulate on the plasma membrane of living cells due to the fast endocytosis and the weakened electrostatic attraction in biological medium, resulting in low chance of passive penetration. The suspended cells after trypsin digestion take more QDs than the adherent cells. A-QDs cause lower cell viability than C-QDs, probably because the approach of positively charged QDs to cells is favored and the smaller aggregates of A-QDs. [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 Si OH/Si O - 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. [ABSTRACT FROM AUTHOR]

Novel hybrid strong anion exchange porous carbon fibers (HACAX) were synthesized and evaluated for adsorption of low concentrations of Cr(VI) at natural pH. Positive surface charge due to pyridinium groups enables HACAX to adsorb Cr(V) rapidly and with high capacity. HACAX showed stable and regenerable performance for adsorbing and converting Cr(VI) into Cr(III) with no change in pH, which is attributed to the catalytic activity of surface oxygen functional groups. [ABSTRACT FROM AUTHOR]

Hybrid porous carbon fibers with strong anion-exchangeable functional groups (HACAX) were synthesized by alkylation of pyrolyzed polyacrylonitrile. HACAX exhibits generic stable positively charged functional groups. This expands the applications of porous carbon media for interacting with anions without adjusting pH, such as Cr(vi) adsorption at natural pH. [ABSTRACT FROM AUTHOR]

Highlights: [•] Reactivation process involves a trigonal bipyramidal structure. [•] The rate-determining step of reactivation process was provided. [•] The H2Oθ-Glu pathway is more feasible for aging process. [•] The electrostatic influences of surrounding amino acids were exhibited. [ABSTRACT FROM AUTHOR]