Search

To develop sensing materials, this study used cheap and readily available graphite, with decalin as solvent to disperse the graphite in low-density polyethylene (LDPE). Two methods of solvent removal (heat treatment at 100 °C and natural drying) were applied. Afterward, two kinds of composite LDPE/graphite films with different proportions of graphite were obtained. Different samples of the two films were compared in terms of the differences in appearance, thermal properties, and resistances. SEM showed that the appearance of heat-treated composite films presented a complete and smooth structure and good bendability relative to untreated films. Thermal gravimetric analysis and differential thermogravimetry showed that composite films with heat treatment had a higher thermal stability. Differential scanning calorimetry results showed that the melting points of the two composite films decreased with increasing graphite content. Finally, these composite films were used to measure the induced voltage values corresponding to changes in pH of different samples. The results showed that stable voltage values could not be obtained in the case of composite materials with very low conductivity, and that an appropriate amount of graphite mixed with LDPE could have better acid–base sensing properties. [ABSTRACT FROM AUTHOR]

Carbon nanotube-doped nano-zinc oxide (CNT-NZnO) was used to reinforce polyvinyl alcohol (PVA) by creating a network consisting of hydrogen and coordination bonding. Composite PVA/CNT-NZnO hydrogels were prepared through ultrasonic solution blending, freezing–thawing cycles, and their mechanical properties, water content, gel fraction, swelling ratio, crystallinity, thermal stability, and antibacterial activity were studied. The composites were characterized using Fourier transform infrared (FTIR) spectroscopy, field emission electron scanning microscopy (FESEM), energy X-ray spectroscopy (EDS), and X-ray diffraction (XRD). When the CNT-NZnO content was increased from 0 to 0.6 phr, the tensile strength greatly increased from 1.1 to 2.3 MPa. Relative to pure PVA hydrogel, composite PVA/CNT-NZnO hyrogels showed increased tensile strength (by 109.1%). Their elongation at break increased from 191.1 to 373.9%, an increase by 182.8% with pure PVA hydrogel as reference. The results of FTIR analysis showed that PVA formed a coordination reaction with CNT-NZnO, synergistically improving the tensile strength of PVA. EDS test analysis showed that of all the filler content considered in this study, 0.6 phr CNT-NZnO was uniformly distributed in the PVA hydrogel the most. The results of XRD analysis showed that when the content of CNT-NZnO was ≤ 0.6 phr, the crystallinity decrased, indicating that the nanofillers were evenly dispersed. When the content was > 0.6 phr, the crystallinity significantly increased, indicating the the nanofillers were not be dispersed well, and agglomeration occurred. The results of SEM analysis showed that the addition of a small amount of CNT-NZnO changed the microstructure of the PVA hydrogel, making the three-dimensional network structure of the composite gel more compact. In addition, CNT-NZnO enhanced the hydrophobicity, dye adsorption, and gave good antibacterial properties to the hydrogels. The new antibacterial composite hydrogel with dye adsorption capacity had excellent mechanical properties and shape recovery ability, and had potential applications in the field of biomedical materials. [ABSTRACT FROM AUTHOR]

AtmChile is an R package that permits the download and management of data from the National Air Quality Information System (SINCA, Spanish acronyms) and the Chilean Meteorological Directorate (DMC, Spanish acronyms) for multiple air quality and climatological parameters in a simple and intuitive platform. The AtmChile package includes the ChileAirQualityApp, a dashboard for enhancing the data download functions of this package with analysis, visualization, and descriptive statistics tools in a user-friendly manner. The AtmChile offers researchers and the public a highly intuitive open access package to download, validate, visualize, and preliminarily analyze air quality and climatological data available in Chile. [ABSTRACT FROM AUTHOR]

Attapulgite (ATT) has never been used as a barrier additive in polypropylene (PP). As a filler, ATT should be added in high content to PP. However, that would result in increased costs. Moreover, the compatibility between ATT and the PP matrix is poor due to the lack of functional groups in PP. In this study, carboxylic groups were introduced to PP to form a modified polypropylene (MPP). ATT was purified, and a low content of it was added to MPP to prepare MPP/ATT nanocomposites. The analysis from FTIR indicated that ATT could react with MPP. According to the results of oxygen and water permeability tests, the barrier performance of the nanocomposite was optimal when the ATT content was 0.4%. This great improvement in barrier performance might be ascribed to the following three reasons: (1) The existence of ATT extended the penetration path of O2 or H2O molecules; (2) O2 or H2O molecules may be adsorbed and stored in the porous structure of ATT; (3) Most importantly, –COOH of MPP reacted with –OH on the surface of ATT, thereby the inner structure of the nanocomposite was denser, and it was less permeable to molecules. Therefore, nanocomposites prepared by adding ATT to MPP have excellent properties and low cost. They can be used as food packaging materials and for other related applications. [ABSTRACT FROM AUTHOR]

Abstract: We prepare highly ordered flexible layers of graphene oxide (GO) on modified polyacrylonitrile substrates by the pressure-assisted self-assembly technique. This composite membrane shows excellent performance during the pervaporation separation of a 70wt.% isopropyl alcohol (IPA)/water mixture: 99.5wt% water in permeate and 2047gm−2 h−1 permeation flux. Despite the specific GO deposition increase from 4.3 to 43.3×10−5 gcm−2 (ninefold layer thickness growth), its effect on the permeation flux is not significant, as manifested by only a little decrease in the flux. At 70°C feed temperature, the permeate water concentration remains 99.5wt% and the permeation flux reaches 4137gm−2 h−1. The high selectivity may be due to the dense GO film consisting of highly ordered and packed laminates, allowing water but inhibiting IPA molecules to pass through. GO is demonstrated to be amphiphilic: water molecules adsorb first at the hydrophilic edge (hydroxides) and then rapidly diffuse through the hydrophobic core (mainly carbon), forming a water passage channel that promotes high permeation flux. When water molecules permeate through the GO layers, they accumulate and form a monolayer structure that pushes the successive layers away from each other, leading to widening of the d-spacing. [Copyright &y& Elsevier]

In this work, exfoliated carboxylated graphene (CG) was used to prepare nanocomposite films of modified polyvinyl alcohol (MPVA) incorporated with maleic anhydride through simple hydrothermal and ultrasonic methods. A 3D network structure formed by strong bonds between CG and MPVA greatly improved the mechanical and barrier properties of MPVA. CG endowed the films with conductivity at high and low temperatures. When the CG content was 2%, the tensile properties, oxygen and water vapor barrier performance of the nanocomposite films were significantly improved. Moreover, CG enhanced the hydrophobicity of MPVA, making the nanocomposite films more water-resistant and durable. Compared with nanocomposites of PVA containing graphene or graphene oxide reported by previous studies, the nanocomposite films with optimal CG content in this present study had greater improvement and better overall performance. This new type of conductive antibacterial nanocomposite films would have potential as packaging materials with improved barrier properties. Nanocomposite films with three possible mechanisms of chemical reaction to form a 3D network structure by strong bonds between carboxylated graphene and modified polyvinyl alcohol. [Display omitted] • Carboxylated graphene and modified polyvinyl alcohol form a 3D network structure. • CG interacts with MPVA via three possible chemical reaction mechanisms. • MPVA/CG has a higher rate of improved tensile strength than PVA/graphene or PVA/GO. • MPVA/CG exhibits a more enhanced O 2 barrier performance than PVA/graphene or PVA/GO. • MPVA/CG nanocomposites show superb antibacterial activity and thermal conductivity. [ABSTRACT FROM AUTHOR]

A nanomaterial in the form of zinc oxide-doped multiwall carbon nanotubes (MWCNTs-ZnO) was synthesized, and new nanocomposites were prepared by blending together different amounts of poly(phenylene sulfide) (PPS) as matrix and MWCNTs–ZnO as fillers in a torque rheometer with an internal mixer. MWCNTs-ZnO enhanced the barrier performance of PPS in terms of crystallinity, path blocking, and coordination reaction. Through tensile test, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, evaluation of Escherichia coli inhibition, and water permeability, the properties of pure PPS and PPS/MWCNTs-ZnO nanocomposites were characterized and compared. The results showed that MWCNTs-ZnO played a role in heterogeneous nucleation. When the content of MWCNTs-ZnO was 0.4 phr, the crystallization temperature, thermostability, tensile strength, elongation at break, and hydrophilicity approached maximum values, and the microscopic morphology changed from the original brittle fracture to a ductile fracture. PPS/MWCNTs-ZnO nanocomposites showed improved barrier performance due to three possible factors: (1) extending the transmission path due to the presence of nanofillers; (2) enhancing crystallization; (3) coordination between PPS and MWCNTs-ZnO. Finally, FTIR analysis showed that PPS and MWCNTs-ZnO formed coordination between them, which improved the properties of nanocomposites. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the microstructural changes in polycarbonate (PC) membranes induced by the CO2 sorption were investigated using the CO2 sorption isotherm data and the positron annihilation lifetime spectroscopy (PALS). The effects of the PC exposure to CO2 at different temperatures and gas pressures on the free-volume distribution were discussed. The distribution at ambient conditions or 5atm He pressure displayed a monomodal curve, whereas that at different CO2 pressures showed a bimodal curve, indicating the presence of small and big free-volume sizes due to the serious plasticization caused by CO2. [Copyright &y& Elsevier]

A new nanomaterial or nano-filler in the form of multiwalled carbon nanotube-zinc oxide (MWCNT-ZnO) was synthesized for the purpose of modifying poly(butylene adipate-co-terephthalate) (PBAT) and its derivative (modified PBAT or MPBAT) through a melt-blending method (MPBAT was obtained by introducing maleic anhydride groups into PBAT). The effect of the new nano-filler on the properties of resultant nanocomposites was determined from the characterization of mechanical properties, morphology, crystallinity, thermal stability, barrier properties, hydrophilicity, conductivity, antibacterial property, and biodegradability. The results showed that MPBAT nanocomposites had stronger mechanical properties, better barrier properties, and higher electrical conductivity than PBAT nanocomposites. Scanning electron microscopy illustrated that MWCNT-ZnO had better compatibility with MPBAT than with PBAT. At 0.2% MWCNT-ZnO, the MPBAT/MWCNT-ZnO nanocomposite film exhibited the greatest mechanical properties (17.74% increase in tensile strength, 22.17% in yield strength, and 14.29% in elongation at break). When the MWCNT-ZnO content was 0.4%, the nanocomposite film demonstrated the best water vapor barrier ability (an increase of 30.4%). The MPBAT/MWCNT-ZnO film with 0.6% MWCNT-ZnO turned out to have the best oxygen barrier performance (an increase of 130% relative to pure PBAT). It was shown from the results of antibacterial evaluation that the new nanomaterial could impart PBAT and MPBAT with antibacterial activity. The biodegradability tests indicated that an MWCNT-ZnO content of 0.2% could slightly reduce the biodegradability, and when the content was higher than 0.2%, the weight loss rate would increase. [ABSTRACT FROM AUTHOR]

Since the inception of research on hollow silica, the use of hollow nanosilica (HNS) as additives in barrier materials has not been reported. In this study, we evaluated the capacity of HNS as an additive in modified polypropylene (MPP). According to X-ray diffraction (XRD), the crystallinity, tensile strength, and thermal stability of MPP/HNS nanocomposite containing 0.1 phr HNS approached maximum values. Moreover, the nanocomposite had the best performance in terms of water vapor barrier and oxygen resistance. The reasons for the improvement in barrier performance were discussed. Scanning electron microscopy revealed that HNS at a low content dispersed well in MPP. In conclusion, the synthesized HNS can be used as an additive in barrier materials, and it would have potential applications in the fields of food packaging films and storage containers or materials. Hollow nanosilica was synthesized, and then it was used as an additive in modified polypropylene to prepare nanocomposites. These new nanocomposites show excellent properties, such as tensile strength, barrier performances and thermostability. The new nanocomposites could be widely used in packaging materials. [ABSTRACT FROM AUTHOR]

Hydrogels with excellent stiffness, toughness, anti‐fatigue, and self‐recovery properties are regarded as promising water‐containing materials. In this work, a dual physically cross‐linked (DPC) sodium alginate (SA)/poly[acrylamide (AAm)‐acrylic acid (AAc)‐octadecyl methacrylate (OMA)]‐Fe3+ hydrogel is reported, which is constructed by hydrophobic association (HA) and ionic coordination (IC). The optimal DPC hydrogel demonstrates excellent mechanical performance: tensile modulus of 0.65 MPa, tensile strength of 3.31 MPa, elongation at break of 1547%, and toughness of 27.8 MJ m–3. SA/P(AAm‐AAc‐OMA)‐Fe3+ DPC hydrogels also exhibit prominent anti‐fatigue and self‐recovery performance (99.1–109.7% modulus recovery and 90.4–108.9% dissipated energy recovery after resting for 5 min without additional stimuli at ambient temperature) through the reconstruction of reversible physical cross‐linking. Some of the SA/P(AAm‐AAc‐OMA)‐Fe3+ DPC hydrogels even exhibit a stretching‐induced strengthening effect, which is similar to the performance of muscle—"the more training, the more strength." Hence, the combination of HA and IC will provide an effective approach to design DPC hydrogels with desirable mechanical performances and a longer service life for wider applications of soft materials. [ABSTRACT FROM AUTHOR]

We fabricated thin-film composite nanofiltration polyamide membranes through the interfacial polymerization of two monomers: polyethyleneimine (PEI) and trimesoyl chloride (TMC). Three different types of surfactants with varied chemical structures were added to aqueous PEI solutions: sodium dodecyl sulfate (SDS), sodium octyl sulfate, and sodium dodecylbenzenesulfonate; the aim was to improve the rejection of divalent ions. Adding the surfactants led to increased isoelectric point, and, in turn, enhanced the membrane hydrophilic properties, heightened the membrane surface charge, and augmented the rejection of MgCl 2. Among the three surfactants, SDS effected the most favorable conditions: the resultant composite membrane delivered the highest pure water flux (44.87 ± 3.22 L∙m−2∙h−1), and exhibited high rejections of divalent salts (R Na2SO4 = 92.26 ± 3.30%; R MgSO4 = 93.83 ± 3.22%; R MgCl2 = 94.15 ± 2.52%). SDS had long alkane chains and highly polar heads, which were conducive to bringing about an effective interaction between PEI and the polysulfone (PSf) support, thereby increasing the sorption of PEI in PSf. Accordingly, the reaction of PEI with TMC produced more amide and amine functional groups that were instrumental in raising the rejections of divalent salts and enhancing the membrane surface properties. Unlabelled Image • Surfactants increment rejection of divalent salts for nanofiltration membranes. • Chemical structure of surfactants affects interfacial polymerization reactions. • Suitable surfactants play a role in enhancing performance of membranes. [ABSTRACT FROM AUTHOR]

Attapulgite (ATT) is a naturally rigid reinforcing filler. In this present study, ATT was first purified, and varying amounts of purified ATT was added to polylactic acid (PLA) to modify PLA through a melt-blending technique. The objective was to determine how the content of ATT affected the characteristics of the ensuing PLA/ATT nanocomposites: morphology, mechanical and thermal properties. Filling PLA with ATT increased both the thermal and mechanical properties, but too much ATT was not beneficial as the effect was to decrease both properties. Energy dispersive spectroscopy indicated that the percentage of Si element increased with the amount of ATT, but more than 10 wt % ATT led to a poor ATT distribution in the nanocomposites. [ABSTRACT FROM AUTHOR]

Bio-composites are known to have poor properties. The reason is the absence of chemical bonding between bio-fillers and polymers. In this present study, we prepared composites with a bio-filler by melt blending distillers grains (DG) with high-density polyethylene (HDPE) and modified HDPE (MHDPE), and compared the characteristics of the composites. Differential scanning calorimetry, thermogravimetry, mechanical property measurement, Fourier transform infrared spectroscopy, contact angle measuring instrument, and water absorption analysis were used to assess DG as a bio-filler. From the results of hydrophilicity measurement, water absorption, morphology, and tensile strength tests, MHDPE was found to have a better interfacial adhesion with DG. The yield strength and crystallinity of DG/MHDPE bio-composites with 50% DG were higher than those of pure HDPE. As DG improved the bio-composite performance, it would have broad application prospects as a bio-filler. [ABSTRACT FROM AUTHOR]

Purpose: Hyperbaric oxygen (HBO) has been advocated in the prevention and treatment of osteoradionecrosis (ORN) of the jaw after head and neck radiation therapy, but supporting evidence is weak. The aim of this randomized trial was to establish the benefit of HBO in the prevention of ORN after high-risk surgical procedures to the irradiated mandible.Methods and Materials: HOPON was a randomized, controlled, phase 3 trial. Participants who required dental extractions or implant placement in the mandible with prior radiation therapy >50 Gy were recruited. Eligible patients were randomly assigned 1:1 to receive or not receive HBO. All patients received chlorhexidine mouthwash and antibiotics. For patients in the HBO arm, oxygen was administered in 30 daily dives at 100% oxygen to a pressure of 2.4 atmospheres absolute for 80 to 90 minutes. The primary outcome measure was the diagnosis of ORN 6 months after surgery, as determined by a blinded central review of clinical photographs and radiographs. The secondary endpoints included grade of ORN, ORN at other time points, acute symptoms, pain, and quality of life.Results: A total of 144 patients were randomized, and data from 100 patients were analyzed for the primary endpoint. The incidence of ORN at 6 months was 6.4% and 5.7% for the HBO and control groups, respectively (odds ratio, 1.13; 95% confidence interval, 0.14-8.92; P = 1). Patients in the hyperbaric arm had fewer acute symptoms but no significant differences in late pain or quality of life. Dropout was higher in the HBO arm, but the baseline characteristics of the groups that completed the trial were comparable between the 2 arms.Conclusions: The low incidence of ORN makes recommending HBO for dental extractions or implant placement in the irradiated mandible unnecessary. These findings are in contrast with a recently published Cochrane review and previous trials reporting rates of ORN (non-HBO) of 14% to 30% and challenge a long-established standard of care. [ABSTRACT FROM AUTHOR]

Highlights: • Reaction of 3,3′-diaminobenzidine (DAB) with polyacyl chlorides was investigated. • Trimesoyl chloride and DAB yielded membranes with excellent performance. • DAB-TMC membranes could be applied to nanofiltration at diverse conditions. Abstract Our present study used 3,3′-diaminobenzidine (DAB) to prepare nanofiltration polyamide membranes. A polyamide layer was formed on a polysulfone (PSf) support through interfacial polymerization; DAB was reacted with different polyacyl chlorides: isophthaloyl chloride, succinyl chloride, and trimesoyl chloride (TMC). Attenuated total reflectance-Fourier transform infrared confirmed the polyamide layer formation. Scanning electron microscopy illustrated that only the reaction between DAB and TMC yielded a defect-free polyamide layer. The membrane preparation conditions comprised the following parameters: DAB and TMC concentrations, immersion time (PSf support in DAB solution), and polymerization reaction time. The optimized membrane delivered an average permeability of 12.5 L m−2 h−1 MPa−1. Its salt rejection followed this order: Na 2 SO 4 (84.2%) > MgSO 4 (48.8%) > MgCl 2 (14.5%) or NaCl (15.3%). Moreover, the membrane was stable at feed pH of 5–10, at operating temperatures of 25–70 °C, and within a long-term nanofiltration period of 148 h. [ABSTRACT FROM AUTHOR]

Abstract We report herein new biocomposites prepared from thermally treated oyster shell powder (TTOSP) and modified polypropylene (PP). Untreated and heat-treated OSP are examined to determine which of them is more effective as a bactericidal agent that can be incorporated into a modified PP to prepare biocomposites. The results of TGA and SEM indicate poor compatibility between PP and biocomposites containing more than 0.5 wt% TTOSP. A quantitative analysis reveals that TTOSP can impart antibacterial activity. MTT assay tests on the biocomposites reveal that the relative growth rates of L929 fibroblast cells increase with the TTOSP content, indicating that the biocomposites exhibit no cytotoxicity. The results from this study suggest that a TTOSP content of as low as 0.5 wt% is sufficient to improve the thermostability and tensile property of PP. Graphical abstract Image 1 Highlights • Thermally treated oyster shell powder (TTOSP) has never been reported to impart antibacterial properties to polymers. • This is the first report that indicates TTOSP could promote the bioactivity of polymers. • TTOSP could substantially improve the themostability and mechanical properties of biocomposites. • TTOSP as potential additives and antibacterial agents for polymer industries. [ABSTRACT FROM AUTHOR]

This study used dicyclohexylmethane 4,4-diisocyanate, polybutylene adipate, polyether-1,3-diol, and 2,6-pyridinedimethanol to synthesize a novel water-based polyurethane (WPU) that contained pyridyl units. To enhance the thermal, mechanical, swelling, and antimicrobial properties of the WPU, various metals (silver nitrate, copper acetate, cobalt acetate, and zinc acetate) were incorporated to form WPU/metal composites. In addition, the study investigated the effects of the metal types on the WPU properties. Fourier transform infrared spectroscopy was used to confirm the synthesis of the WPU containing pyridine. Atomic force microscopy illustrated that the added metals increased the WPU surface roughness. The contact angle and degree of swelling tests demonstrated that the added metal reduced the WPU hydrophilicity, and with the addition of other metal types, the hydrophobicity increased considerably. Thermal gravimetric analysis indicated that the initial decomposition temperature of the highest WPU thermal stability was attributed to zinc. In addition, the results of differential scanning calorimetry and dynamic mechanical analysis showed that adding a small amount of metal increased the hard and soft segment glass transition temperatures. A universal strength tester validated that the WPU mechanical properties varied with the different metal additives and that the WPU strength increased. However, the WPU toughness and ductility decreased with the addition of metals; silver provided the highest mechanical strength. An antimicrobial test indicated that silver enhanced the antimicrobial property. The moisture permeability and waterproof property of the WPU coating was also analyzed. [ABSTRACT FROM AUTHOR]

Hydrogels as flexible strain sensors (FSSs) have attracted tremendous interest in the area of human movement monitoring. Such an application is developing rapidly. However, it is still valuable to explore hydrogel-based FSSs with excellent mechanical properties, responsiveness to stimulus, high strain sensitivity, and reliable stability. Herein, a hydrogel with triple physical cross-linking (TPC hydrogel), whose structure also included hydrophobic association-microcrystallinity-ionic coordination, was designed and fabricated. Synthetic water-soluble polymer [poly(vinyl alcohol) (PVA)] and natural polymer [sodium alginate (SA)] were introduced into the hydrogel; PVA induced microcrystal cross-linking, while SA provided ionic conductivity for the hydrogel. TPC hydrogels exhibited high toughness (5.9 MJ/m3) and excellent deformation (2490%). The introduction of SA also endowed the hydrogels with improved capability to ionize, imparting them with excellent pH-responsive swelling behavior. Impressively, TPC hydrogel-based FSSs exhibited reasonable conductivity (0.65–2.47 S/m), high sensitivity (maximum gauge factor = 10.29), and outstanding reliability and stability. This investigation broadens the avenue for the design and fabrication of hydrogels intended as FSSs with low modulus (33–45 kPa, close to human skin), excellent stretchability, and high strain sensitivity and durability. [Display omitted] • Tough hydrogels with triple physical cross-linking and large deformation. • pH-Responsive swelling behaviors. • Hydrogels with resonable conductivity provided by ions. • Stable and durable strain sensitivity. [ABSTRACT FROM AUTHOR]

• SHNT with large aspect ratio increases Li+ channels and electrochemical performance. • Thermoplastic materials ensure membrane stability in battery charging-discharging. • DMA-AFM expounds the fabrication of robust, flexible, and safe battery separators. Membrane separators should have robust characteristics to ensure that batteries have a high discharge capacity and could shun the probability of thermal runaway. In this study, thermoplastic polyurethane (TPU) and inorganic surface-modified halloysite nanotube (SHNT) are considered to improve the toughness and strength of electrospun polyacrylonitrile (PAN) fibers. This is because TPU is elastic, while SHNT has a high aspect ratio and a special hollow structure. The obtained PAN/TPU/SHNT membrane exhibits improvement in its overall performance. It exhibits excellent thermal stability, increased flexibility, and high ionic conductivity. More importanly, the tensile strength of membranes increases to 28.5 MPa and observed a significant vibration amplitude, which is signifying better flexibility and elasticity. With PAN/TPU/SHNT-3 as a battery separator, the lithium-ion battery delivers a capacity of 108.41 mAh/g and a retention of 98.30 % at 2C for 100 cycles. These data on capacity and retention are higher than those of Celgard 2400. Incorporating SHNT to improve the fiber strength and TPU for its elasticity into electrospun PAN membrane separators should prove effective in enhancing not only the electrochemical performance but also the safety of batteries. [ABSTRACT FROM AUTHOR]

To synthesize antibacterial polyurethane (PU) films, a novel chain extender, bis(3-pyridinemethanol) silver (BPDS), and a PU prepolymer were also synthesized through coordination and covalent reactions. The effects of incorporating different amounts of BPDS were investigated by characterizing the BPDS/PU films using various instruments: FTIR, TGA, DSC, DMA, XRD, EDX, universal testing machine, contact angle goniometer, and positron annihilation spectroscopy (PALS). With a higher BPDS content, the glass transition temperature, final degradation temperature, and Young's modulus were all enhanced; however, the tensile strength and elongation at break were both reduced. PALS analysis revealed that the more rigid and randomly packed structure of the BPDS/PU films at a higher BPDS content was characterized by a broader free volume size distribution that consisted largely of much smaller free volume holes. Quantitative tests with Staphylococcus aureus and Escherichia coli indicated excellent antibacterial properties, suggesting that the PU films could be used repeatedly. [ABSTRACT FROM AUTHOR]

Background: The community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) epidemic in the United States is attributed to the spread of the USA300 clone. An epidemic of CA-MRSA closely related to USA300 has occurred in northern South America (USA300 Latin-American variant, USA300-LV). Using phylogenomic analysis, we aimed to understand the relationships between these 2 epidemics.Methods: We sequenced the genomes of 51 MRSA clinical isolates collected between 1999 and 2012 from the United States, Colombia, Venezuela, and Ecuador. Phylogenetic analysis was used to infer the relationships and times since the divergence of the major clades.Results: Phylogenetic analyses revealed 2 dominant clades that segregated by geographical region, had a putative common ancestor in 1975, and originated in 1989, in North America, and in 1985, in South America. Emergence of these parallel epidemics coincides with the independent acquisition of the arginine catabolic mobile element (ACME) in North American isolates and a novel copper and mercury resistance (COMER) mobile element in South American isolates.Conclusions: Our results reveal the existence of 2 parallel USA300 epidemics that shared a recent common ancestor. The simultaneous rapid dissemination of these 2 epidemic clades suggests the presence of shared, potentially convergent adaptations that enhance fitness and ability to spread. [ABSTRACT FROM AUTHOR]

Traditionally, polyacrylonitrile (PAN) is coated with a selective layer to tailor it for dehydrating butanol by pervaporation. But we hydrolyzed PAN with sodium hydroxide for such a purpose. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAN׳s CN group was hydrolyzed to CONH 2 , which was further converted to COOH. As a result, the hydrolyzed PAN (HPAN) was made more hydrophilic, as evidenced from water contact angle data. CONH 2 and COOH formed hydrogen bonds between them, causing molecular chains to rearrange (according to X-ray diffraction) and pores to shrink (shown by scanning electron microscopy). Positron annihilation lifetime spectroscopy revealed that hydrolysis led to free volume radius decrease; however, prolonged hydrolysis caused breakage of molecular chains. The HPAN produced after 4 h hydrolysis exhibited narrow free volume distribution and delivered exceptional performance (water concentration in permeate=99.1 wt%; permeation flux=2.03 kg/m 2 h). [ABSTRACT FROM AUTHOR]

Abstract: In this study, the lifetime spectra of positron annihilation for CO2-exposed zeolite 4A at different conditions were measured. The effects of subjecting zeolite 4A to baking treatment and exposing it to CO2 at different pressures on the positronium (Ps) annihilation characteristics was investigated using positron annihilation lifetime spectroscopy (PALS). Zeolite 4A was chosen as the medium because of its rigidity, stability, and well-understood structure. Its structure consists of cavities that can be classified into two types: α-cage and β-cage. Zeolite 4A at vacuum (or dehydrated) conditions gave the longest lifetime, whereas that at ambient (or hydrated) conditions, at which water molecules are sorbed in the cavities of zeolite 4A, gave the shortest lifetime. The water molecules in zeolite 4A cavities would inhibit the ortho-positronium (o-Ps) formation probability. At lower gas sorption, the CO2 gas molecules exhibited the pore-filling effect, resulting in a decrease in the o-Ps lifetime. However, at higher CO2 sorption, the shielding effect in the α-cage increased with CO2 pressure and led to an increase in the o-Ps lifetime. When the α-cage cavity was filled with the CO2 gas molecules at pressures greater than 5atm, o-Ps tended to migrate from the α-cage to the β-cage. [Copyright &y& Elsevier]

Abstract: In this study, SiOCH films for gas separation were prepared on a mixed cellulose ester (MCE) substrate by means of plasma-enhanced chemical vapor deposition (PECVD) using octamethylcyclotetrasiloxane (OMCTS) as a precursor. The RF power was the major variable in adjusting the pore structure of the SiOCH film. The FTIR analysis showed that there was a breakup of the Si–O–Si cyclic ring with increasing RF power. According to the positron annihilation lifetime spectroscopy (PALS) characterization, the SiOCH films had two different pore sizes as indicated by the following: τ 3 forming the matrix structure and τ 4 representing big cages. The range of the pore radius was 3.52–3.78Å for the matrix structure and 6.31–7.47Å for big cages. With the RF power increasing to 150W from 50W, the SiOCH films showed a higher crosslinking, resulting in a decrease in gas permeability (for example, 40–14GPU for O2) and an increase of O2/N2 selectivity from 1.67 to 2.31. At the same time, based on FTIR and PALS analyses, the OMCTS cyclic ring would open up and then form a small amount of larger pores (τ 4). Based on the FTIR analysis, all the SiOCH films prepared at different RF power showed a very high organic character that indicated values of I(Si–CH3)/I(Si–O–Si) higher than 0.65. [ABSTRACT FROM AUTHOR]

Abstract: A series of aromatic polyamide membranes for the pervaporation separation of aqueous ethanol mixtures was investigated. It was found that the permeation rate could be increased by the introduction of bulky substituted groups and arylene ether groups into the polymer backbone. The influence of the substituted group structure on the free volume in and the pervaporation performance of the aromatic polyamide membranes were systematically analyzed by positron annihilation spectroscopy (PAS) and molecular dynamics (MD) simulation. The trend of the ortho-positronium (o-Ps) lifetime and the free-volume size data evaluated by the PAS measurement and the MD simulation was highly consistent with the chemical structure of the aromatic polyamide pervaporation membranes. [Copyright &y& Elsevier]

Comments on a report on G-protein-independent signaling events mediated by 7-transmembrane receptors. Information on ceramide generation; Significance of two receptors to sphingomyelin hydrolysis.

Nonmelanoma skin cancer is one of the most common malignancies in humans. Different therapeutic strategies for the treatment of these tumors are currently being investigated. Given the growth-inhibiting effects of cannabinoids on gliomas and the wide tissue distribution of the two subtypes of cannabinoid receptors (CB(1) and CB(2)), we studied the potential utility of these compounds in anti-skin tumor therapy. Here we show that the CB(1) and the CB(2) receptor are expressed in normal skin and skin tumors of mice and humans. In cell culture experiments pharmacological activation of cannabinoid receptors induced the apoptotic death of tumorigenic epidermal cells, whereas the viability of nontransformed epidermal cells remained unaffected. Local administration of the mixed CB(1)/CB(2) agonist WIN-55,212-2 or the selective CB(2) agonist JWH-133 induced a considerable growth inhibition of malignant tumors generated by inoculation of epidermal tumor cells into nude mice. Cannabinoid-treated tumors showed an increased number of apoptotic cells. This was accompanied by impairment of tumor vascularization, as determined by altered blood vessel morphology and decreased expression of proangiogenic factors (VEGF, placental growth factor, and angiopoietin 2). Abrogation of EGF-R function was also observed in cannabinoid-treated tumors. These results support a new therapeutic approach for the treatment of skin tumors. [ABSTRACT FROM AUTHOR]

High-throughput phenotypic screens using biochemical perturbations and high-content readouts are constrained by limitations of scale. To address this, we establish a method of pooling exogenous perturbations followed by computational deconvolution to reduce required sample size, labor and cost. We demonstrate the increased efficiency of compressed experimental designs compared to conventional approaches through benchmarking with a bioactive small-molecule library and a high-content imaging readout. We then apply compressed screening in two biological discovery campaigns. In the first, we use early-passage pancreatic cancer organoids to map transcriptional responses to a library of recombinant tumor microenvironment protein ligands, uncovering reproducible phenotypic shifts induced by specific ligands distinct from canonical reference signatures and correlated with clinical outcome. In the second, we identify the pleotropic modulatory effects of a chemical compound library with known mechanisms of action on primary human peripheral blood mononuclear cell immune responses. In sum, our approach empowers phenotypic screens with information-rich readouts to advance drug discovery efforts and basic biological inquiry., (© 2024. The Author(s).)

This study is a comprehensive analysis of the oxidative potential (OP) of particulate matter (PM) and its environmental and health impacts. The researchers conducted a bibliometric analysis and scoping review, screening 569 articles and selecting 368 for further analysis. The study found that OP is an emerging field of study, with a notable increase in the number of publications in the 2010s compared to the early 2000s. The research is primarily published in eight journals and is concentrated in a few academic and university-based institutions. The study identified key research hotspots for OP-PM, emphasizing the importance of capacity building, interdisciplinary collaboration, understanding emission sources and atmospheric processes, and the impacts of PM and its OP. The study highlighted the need to consider the effects of climate change on OP-PM and the regulatory framework for PM research. The findings of this study will contribute to a better understanding of PM and its consequences, including human exposure and its effects. It will also inform strategies for managing air quality and protecting public health. Overall, this study provides valuable insights into the field of OP-PM research and highlights the need for continued research and collaboration to address the environmental and health impacts of PM.

The World Health Organization strongly supports breastfeeding as the main source of infant feeding to ensure maternal and child health. Since its emergence, COVID-19 has become a disease affecting the health of the world's population, and vaccines have been developed to prevent it. However, the decision to license COVID-19 vaccines for infants under 6 months of age has been delayed. Different studies have shown that during the breastfeeding period, the benefit-risk balance is much higher in favor of the benefit, at the immunological level for the infant, due to its low perception of adverse effects and the low transmission of products such as mRNA from the mother to the child. Different organizations and societies recommend vaccination in breastfeeding women. COVID-19 vaccines have been shown to be safe and effective., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

In this work, silica nanoparticles were produced in situ, to be embedded eventually in the polyamide layer formed during interfacial polymerization for fabricating thin-film nanocomposite membranes with enhanced performance for dehydrating isopropanol solution. The nanoparticles were synthesized through a sol-gel reaction between 3-aminopropyltrimethoxysilane (APTMOS) and 1,3-cyclohexanediamine (CHDA). Two monomers-CHDA (with APTMOS) and trimesoyl chloride-were reacted on a hydrolyzed polyacrylonitrile (hPAN) support. To obtain optimum fabricating conditions, the ratio of APTMOS to CHDA and reaction time were varied. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) were used to illustrate the change in morphology as a result of embedding silica nanoparticles. The optimal conditions for preparing the nanocomposite membrane turned out to be 0.15 (g/g) APTMOS/CHDA and 60 min mixing of APTMOS and CHDA, leading to the following membrane performance: flux = 1071 ± 79 g∙m -2 ∙h -1 , water concentration in permeate = 97.34 ± 0.61%, and separation factor = 85.39. A stable performance was shown by the membrane under different operating conditions, where the water concentration in permeate was more than 90 wt%. Therefore, the embedment of silica nanoparticles generated in situ enhanced the separation efficiency of the membrane.

Background and Purpose: Research on demyelinating disorders aims to find novel molecules that are able to induce oligodendrocyte precursor cell differentiation to promote central nervous system remyelination and functional recovery. Δ 9 -Tetrahydrocannabinol (THC), the most prominent active constituent of the hemp plant Cannabis sativa, confers neuroprotection in animal models of demyelination. However, the possible effect of THC on myelin repair has never been studied., Experimental Approach: By using oligodendroglia-specific reporter mouse lines in combination with two models of toxin-induced demyelination, we analysed the effect of THC on the processes of oligodendrocyte regeneration and functional remyelination., Key Results: We show that THC administration enhanced oligodendrocyte regeneration, white matter remyelination and motor function recovery. THC also promoted axonal remyelination in organotypic cerebellar cultures. THC remyelinating action relied on the induction of oligodendrocyte precursor differentiation upon cell cycle exit and via CB 1 cannabinoid receptor activation., Conclusions and Implications: Overall, our study identifies THC administration as a promising pharmacological strategy aimed to promote functional CNS remyelination in demyelinating disorders., (© 2021 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Fibromyalgia (FMS) is a complex clinical syndrome that includes many symptoms beyond chronic pain. The studies that have addressed brain morphometry in FMS have had very heterogeneous results. Thus, the question of which specific FMS symptoms and clinical features-pain, but also psychological distress, sleep-related problems, health status, and medication intake-impact on brain morphometry remains open. Here, we wanted to determine if brain changes in FMS are "symptom-related" more than "diagnostic-related". We performed an observational study of 46 premenopausal women (23 FMS patients and 23 age-matched healthy participants). Magnetic resonance images were analyzed using voxel-based morphometry and subcortical segmentation. We used multiple regression models to assess the associations between total and local brain volumes and FMS clinical characteristics. Furthermore, we calculated associations between subcortical structures' shapes and volumes and FMS clinical characteristics. Larger psychological distress, anxiety, and sleepiness, and higher analgesic consumption accounted for 38 % of FMS patients' smaller total gray matter volume (GMV). For both groups, local decrements of GMV in the medial orbitofrontal cortex were associated to larger psychological distress. Local increases of GMV were positively related to pain scores (superior frontal gyrus), psychological distress (cerebellum), anxiety (medial orbitofrontal cortex), and sleepiness (frontal superior medial cortex). FMS clinical characteristics were also associated to deformations in subcortical structures and volumes changes. This study reveals that total and local GMV changes in FMS go beyond the traditional "pain matrix" alterations. We demonstrated that brain morphology is altered by pain, but also by clinical characteristics that define the FMS experience.

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors.