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Graphene quantum dots (GQDs) are emerging disinfectants, owing to their distinctive photodynamic and antibacterial activities. Halogen-based antimicrobial materials are also known to be effective against infectious pathogens. In this work, we have developed visible light-activatable halogen/nitrogen co-doped polymeric graphene quantum dots [X/N–PGQDs, (X = Cl, Br, I)] as an antibacterial agent, prepared from spermidine and hydrohalic acid by a simple one-step heating method. We demonstrate that these high positively charged X/N–PGQDs are effective antibacterial agents (minimum inhibitory concentration (MIC) less than 0.5 μg mL−1) for the inhibition of both Gram-positive and Gram-negative bacteria. The antibacterial activities of X/N–PGQDs are enhanced upon exposure to white LED light irradiation due to the generation of reactive oxygen species (ROS) which induce oxidative stress, as well as physical disruption of the bacteria. Moreover, the MIC of X/N–PGQDs with LED light irradiation is 100-fold lower than in the dark, revealing their strong photo-induced inactivation of bacteria. X/N–PGQDs are effective for the eradication of multidrug-resistant bacteria in infectious wounds, even with just 1-min of irradiation. With their negligible cytotoxicity, we believe that X/N–PGQDs have great potential as a visible light-activated antibacterial nanomaterial for preclinical application in wound healing.

International audience; Copper/bismuth sulfide heterojunctions boost the catalytic and photoresponsive properties engendered antibacterial activity against clinically isolated multidrug-resistant bacteria and their associated biofilms.We report a one-pot facile synthesis of highly photoresponsive bovine serum albumin (BSA) templated bismuth-copper sulfide nanocomposites (BSA-BiZ/CuxS NCs, where BiZ represents in situ formed Bi2S3 and bismuth oxysulfides (BOS)). As-formed surface vacancies and BiZ/CuxS heterojunctions impart superior catalytic, photodynamic and photothermal properties. Upon near-infrared (NIR) irradiation, the BSA-BiZ/CuxS NCs exhibit broad-spectrum antibacterial activity, not only against standard multidrug-resistant (MDR) bacterial strains but also against clinically isolated MDR bacteria and their associated biofilms. The minimum inhibitory concentration of BSA-BiZ/CuxS NCs is 14-fold lower than that of BSA-CuxS NCs because their multiple heterojunctions and vacancies facilitated an amplified phototherapeutic response. As-prepared BSA-BiZ/CuxS NCs exhibited substantial biofilm inhibition (90%) and eradication (>75%) efficiency under NIR irradiation. Furthermore, MRSA-infected diabetic mice were immensely treated with BSA-BiZ/CuxS NCs coupled with NIR irradiation by destroying the mature biofilm on the wound site, which accelerated the wound healing process via collagen synthesis and epithelialization. We demonstrate that BSA-BiZ/CuxS NCs with superior antimicrobial activity and high biocompatibility hold great potential as an effective photosensitive agent for the treatment of biofilm-associated infections.

We report a one-pot facile synthesis of highly photoresponsive bovine serum albumin (BSA) templated bismuth-copper sulfide nanocomposites (BSA-BiZ/Cu

We demonstrate a single-shot and image-based polarization detection system for material recognition. The Stokes parameters are measured under a single-shot measurement using 4 electrically tunable liquid crystal wave plates, 4 polarizers, and 4 camera modules. The optical principle is introduced and the experiments are performed. We also use a metallic plate and a glass substrate to demonstrate the material recognition. The impact of this study is to provide a practical way in image-based polarization detection in Advanced Driver Assistance Systems for material recognition which could help in driving safety.

We have an addendum for our previous paper [Opt. Express 30, 22768 (2022)10.1364/OE.461378] cite previous prior works from the N. A. Riza lab that earlier reported a high speed lens based on digital polarization switching in cascade with birefringent fixed and tunable optical beamforming elements and its application for volumetric displays.

Nanocomposites were produced via sol–gel reactions for tetraethylorthosilicate within the cluster morphology of perfluorosulfonic acid films. Small-angle x-ray scattering revealed that the polar/nonpolar nanophase-separated morphological template persists despite invasion by the silicon oxide phase. Scanning electron microscopy (ESEM–EDAX) studies have indicated that the greatest silicon oxide concentration occurs near the surface and decreases to a minimum in the middle. Optical and ESEM micrographs revealed a brittle, surface-attached silica layer at high silicon oxide contents. © 1995 John Wiley & Sons, Inc.

The effects of different plasticizers on the structural features of PVC were investigated. Particular emphasis was on the fine structure as denoted by small-angle X-ray scattering (SAXS). The influence of plasticizer content on the mechanical response was followed by dynamic mechanical spectroscopy. The particular plasticizers investigated principally were diethylhexyl succinate and dibutyl phthalate, although other phthalate plasticizers were investigated including dibutyl succinate and dibutyl sebacate. It was noted that structural features at the 100– to 200–a level were systematically influenced by the type and amount of plasticizer and in particular by its solubility parameter. To account for the observed behavior, a model was proposed which speculates that the absorption of plasticizer is nonuniform within the system and in particular within the local regions where crystallites exist. The level of swelling of plasticizer into the amorphous regions at some distance from the crystallites is d...

Poly(dimethylsiloxane) (PDMS) macromonomers of controlled molar masses, narrow molar mass distributions, and high percent functionalities were synthesized through the utilization of the living anionic ring-opening polymerization of hexamethylcyclotrisiloxane. The resultant methacryloxy-functionalized macromonomers were statistically copolymerized with methyl methacrylate to form the title graft copolymers of various chemical compositions. Surface segregation of the low surface energy component, PDMS, was established

Physical structure was determined for colloidal particles of a hydrophobic polysilicate sample dispersed in nonaqueous media. Some silicone products are compounded with such a material which is made by capping water-soluble silicates with organosilyl groups. Solutions densities and viscosities were measured and GPC, SAXS, and TEM were performed on the sample dispersed in THF and PDMS fluid media. Results showed that particles are relatively compact with little solvation or aggregation and have a reasonably spherical shape. The approximate ranges of particle diameter and molecular weight are, respectively, 2 to 10 nm and 2000 to 200,000 with broad, bimodal distributions. The larger particles seem to have lower densities within their hydrodynamic volumes than do the smaller ones. The average “hard-core” density is 1.17 g/cm3, similar to that of many (R SiO 3 2 ) x silicone resins but much less than that of amorphous fused silica. The difference is attributed to poorly packed silicate structures in the polysilicate and silicone resins.

Transparent hybrid materials have been prepared by incorporating either an alumina or titania alkoxide sol with triethoxysilane end-capped polytetramethylene oxide (PTMO) oligomer. In order to avoid undesirable precipitation after the addition of water, a β-dicarbonyl ligand, ethyl acetoacetate, was used. Triethoxysilane endcapped polytetramethylene oxide with a molecular weight of 2000 (g/mol) was chosen to react with either the alumina or titania sol to demonstrate the features of the reaction scheme. The extent of reaction leading to network formation has been qualitatively followed by infrared spectroscopy. A series of solid films were prepared by varying the molar ratio of either aluminum tri(sec-butoxide) or titanium tetraisopropoxide to ethyl acetoacetate, and the weight fraction of alumina or titania to that of PTMO. The refractive index as well as the general structure-property behavior of these hybrid materials were studied.

Materiau hybride ayant une bonne transparence optique et un comportement mecanique tres different de celui des verres sol-gel purs

Polytetramethylene oxide based polyurethane oligomers with multiple triethoxysilane groups have been successfully incorporated into a TEOS based silicate network. It is observed that the incorporation of these oligomeric compounds was enhanced by the presence of additional functional groups along their backbone. The materials produced showed significant improvement in both tensile modulus and strength over previous organic-inorganic hybrid systems. As the number of functional groups per molecule increased, the stiffness of the material increased and the oligomeric T g shifted to higher temperatures. Also, the SAXS correlation distance decreased systematically. A schematic model suggested previously can still be used to interpret these results. Other effects of TEOS content and ageing are also reported and discussed.

Carboxyl functional poly(arylene ether) oligomers of controlled number average molecular weight were synthesized via nucleophilic aromatic substitution step polymerization using p-hydroxy benzoic acid as the molecular weight and end group controlling reagents. The subsequent functionalized polyarylene ethers were copolymerized with acetoxy benzoic acid or acetoxyphenoxy benzoic acid via melt acidolysis procedures. Successful copolymers were generated using chlorobenzene as a solvent for the first s age of the reaction followed by melt reaction at temperatures as high as 325°C. Resulting copolymer composition and segment size were investigated. It was possible to prepare improved solvent resistant copolymers through incorporation of the liquid crystal polyester (LCP) segment. Extraction tests using boiling chloroform showed that a high percentage of segmented copolymer were generated. Swelling characteristics were also noted and were observed to decrease as a function of the LCP concentration utilized. Multiple transitions were observed in differential scanning calorimetry consistent with Tg's, Tm's and possibly with liquid crystal transitions. Optical microscopy showed an ordered microstructure developed which is consistent with the presence of liquid crystalline phases. The materials were successfully compression molded to afford tough coherent films at all compositions, implying the likelihood of improved compressive strength relative to the LCP homo- or copolyesters.

The synthesis, structure/property behavior of inorganic-organic hybrid network materials prepared by the sol gel process have been chronologically reviewed with emphasis on those systems prepared in the authors laboratory. Specific features of reactions as well as the nature of reactants are included. The morphological features of these “ceramer” systems formed have many features in common even though the reactants may be quite different. The mechanical properties of the final materials in conjunction with SAXS have proven beneficial in establishing the basics of their morphological texture. Finally, it is demonstrated how microwave radiation in some cases, can serve as an efficient way in processing the ceramer systems.

Novel transparent hybrid materials incorporating triethoxysilane endcapped poly(tetramethylene oxide) with tetramethoxysilane have been successfully prepared by a sol-gel process. The molecular weight of PTMO has been varied to study its effect on the structure-property behavior of these hybrid materials. Mechanical properties and dynamic mechanical behavior have been measured; small angle X-ray scattering (SAXS) has been utilized to obtain structural information. Based on the experimental results, a simplified morphological model has been suggested to describe these new hybrid systems.

A sol-gel process has been successfully utilized to produce hybrid materials incorporating polymeric/oligomeric components of polydimethyl siloxane(PDMS) with silicon glasses. All the samples made were transparent and flexible. Dynamic mechanical studies indicate that a portion of the siloxane species is phase-separated while the remainder is well dispersed. The effect of acid content were proven to be significant on the dispersion of the siloxane components and on the structure and properties of final products.