Correlations between adhesion and molecular interactions at buried interfaces of model polymer systems and in commercial multilayer barrier films.

Sum frequency generation vibrational spectroscopy (SFG) was applied to characterize the interfacial adhesion chemistry at several buried polymer interfaces in both model systems and blown multilayer films. Anhydride/acid modified polyolefins are used as tie layers to bond dissimilar polymers in multilayer barrier structures. In these films, the interfacial reactions between the barrier polymers, such as ethylene vinyl alcohol (EVOH) or nylon, and the grafted anhydrides/acids provide covalent linkages that enhance adhesion. However, the bonding strengths vary for different polymer-tie layer combinations. Here, using SFG, we aim to provide a systematic study on four common polymer-tie interfaces, including EVOH/polypropylene-tie, EVOH/polyethylene-tie, nylon/polypropylene-tie, and nylon/polyethylene-tie, to understand how the adhesion chemistry varies and its impact on the measured adhesion. Our SFG studies suggest that adhesion enhancement is driven by a combination of reaction kinetics and the interfacial enrichment of the anhydride/acid, resulting in stronger adhesion in the case of nylon. This observation matches well with the higher adhesion observed in the nylon/tie systems in both lap shear and peel test measurements. In addition, in the polypropylene-tie systems, grafted oligomers due to chain scission may migrate to the interface, affecting the adhesion. These by-products can react or interfere with the barrier-tie chemistry, resulting in reduced adhesion strength in the polypropylene-tie system.

KPC variants conferring resistance to ceftazidime-avibactam in Pseudomonas aeruginosa strains.

BACKGROUND: This study aimed to characterize three KPC variants (KPC-33, KPC-100, and KPC-201) obtained from a clinical isolate of Pseudomonas aeruginosa (#700), along with two induced strains C109 and C108. METHODS: Genomic DNAs of #700 (ST235), C109 (ST463), and C108 (ST1076) were sequenced using Illumina and Oxford Nanopore technologies. The transferability and stability of the plasmid was assessed through conjugation experiments and plasmid stability experiments, respectively. Minimum inhibitory concentrations of bacterial strains were determined using broth microdilution methods. In vitro induction was performed using ceftazidime-avibactam (CZA) at concentrations of 6/4 µg/ml. Linear genomic alignments were visualized using Easyfig, and protein structure modeling of the novel KPC variant (KPC-201) was conducted using PyMol. RESULTS: The plasmids carrying the KPC variants in the three CZA-resistant strains (C109, C108, and #700) had sizes of 39,251 bp (KPC-100), 394,978 bp (KPC-201), and 48,994 bp (KPC-33). All three plasmids belonged to the IncP-like incompatibility (Inc) groups, and the plasmid exhibited relatively high plasmid stability, KPC-33 and KPC-201-harboring plasmids were successfully transferred to the recipient strain P. aeruginosa PAO1rifR. The genetic environments of the three blaKPC genes differed from each other. The mobile elements of the three blaKPC genes were as follows, TnAS1-IS26-ΔISKpn27-blaKPC-33-ISKpn6-IS26, IS6-ΔISKpn27-blaKPC-100-ISKpn6-IS26-Tn3-IS26, and IS6100-ISKpn27-blaKPC-201-ISKpn6-TnAS1. Notably, the length of ΔISKpn27 upstream of the blaKPC-33 and blaKPC-100 genes were remarkably short, measuring 114 bp and 56 bp, respectively, deviating significantly from typical lengths associated with ISKpn27 elements. Moreover, the novel KPC variant, KPC-201, featured a deletion of amino acids LDR at positions 161-163 in KPC-3, resulting in a looser pocket structure contributing to its avibactam resistance. CONCLUSIONS: KPC-201, identified as a novel KPC variant, exhibits resistance to CZA. The presence of multiple mobile elements surrounding the blaKPC-variant genes on stable plasmids is concerning. Urgent preventive measures are crucial to curb its dissemination in clinical settings.

Cell Membrane-Anchored AND Logic Gate Aptasensor for Tumor Cell-Specific Imaging with Improved Accuracy.

Accurate and rapid imaging of tumor cells is of vital importance for early cancer diagnosis and intervention. Aptamer-based fluorescence sensors have become a potent instrument for bioimaging, while false positives and on-target off-tumors linked to single-biomarker aptasensors compromise the specificity and sensitivity of cancer imaging. In this paper, we describe a sequential response aptasensor for precise cancer cell identification that is based on a DNA "AND" logic gate. Specifically, the sensor consists of three single-stranded DNA, including the P-strand that can sensitively respond to an acid environment, the L-strand containing the ATP aptamer sequence, and the R-strand for target cell anchoring. These DNA strands hybridize with one another to create a Y-shaped structure (named Y-ALGN). The aptamer in the R-strand is utilized to anchor the sensor to the target cell membrane primarily. Responding to the extracellular acidic environment of the tumor (input 1), the I-motif sequence forms a tetramer structure so that the P-strand is released from the Y-shaped structure and exposes the ATP binding sites in the L-strand. Extracellular ATP, as input 2, continuously operates the DNA aptasensor to complete the logic computation. Upon the sequential response of both protons and ATP molecules, the aptasensor is activated with restored fluorescence on a particular cancer cell membrane. Benefiting from the precise computation capacity of the "AND" logic gate, the Y-ALGN aptasensor can distinguish between MCF-7 cells and normal cells with high accuracy. As a simple and dual-stimuli-responsive strategy, this nanodevice would offer a fresh approach for accurately diagnosing tumor cells.

Effects of exercise interventions on cancer-related fatigue in children with cancer: A meta-analysis.

BACKGROUND: Cancer-related fatigue (CRF) emerges as a common symptom in pediatric cancer patients during treatment. Exercise interventions are increasingly being used as CRF interventions to improve CRF in children with cancer. AIM: The objective of this meta-analysis was to synthesize the best available evidence concerning the effectiveness of exercise interventions for cancer-related fatigue in children with cancer. METHODS: Six databases were extensively searched from inception to December 2023 to identify relevant randomized controlled trials. The risk of bias and methodological quality were assessed using the Cochrane appraisal tool. Pooled effects were calculated using a random-effects model. Heterogeneity was assessed using the I2 test. RESULTS: Eight trials (n = 465) were finally included. Exercise was statistically more effective than conventional care in improving CRF in children with cancer (SMD = -0.62, 95% CI [-1.21, -0.03]) with high statistical heterogeneity (p = .004; I2 = 86%). The results of the subgroup analysis showed that intervention duration <12 weeks (p < .05), exercise frequency ≥ 3 times/week (p < .05), and exercise duration <45 min/time (p < .05) were more effective in improving CRF in children with cancer. LINKING EVIDENCE TO ACTION: Our results suggest that exercise interventions are effective in reducing CRF in children with cancer. We recommend exercise frequency ≥ 3 times/week, exercise duration <45 min/time, and intervention duration <12 weeks.

Genomic profiling and immune phenotyping of neuroendocrine bladder cancer.

PURPOSE: Neuroendocrine bladder cancer (NEBC) poses a formidable clinical challenge and attracts keen interests to explore immunotherapy as a viable treatment option. However, a comprehensive immunogenomic landscape has yet to be thoroughly investigated. EXPERIMENTAL DESIGN: Leveraging a long-term cohort of natural NEBC cases, we employed a multimodal approach integrating genomic (n = 19), transcriptomic (n = 3), single-cell RNA sequencing (n = 1), and immunohistochemical analyses (n = 34) to meticulously characterize the immunogenicity and immunotypes of primary NEBC tumors. Clinical, pathological, medical imaging, and treatment information was retrospectively retrieved and analyzed. RESULTS: Our study unveiled that despite a considerable mutational burden, NEBC was typically immunologically inactive, as manifested by 'immune-excluded' or 'immune-desert' microenvironment. Interestingly, a subset of mixed NEBC with concurrent urothelial bladder cancer (UBC) histology displayed an 'immune-infiltrated' phenotype with prognostic relevance. When compared to UBC, NEBC lesions were distinguished by a denser cellular composition and augmented peritumoral extracellular matrix, which might collectively impede lymphatic infiltration. As a result, single-agent immune checkpoint inhibitors demonstrated limited efficacy against NEBC, while pharmacologic immunostimulation with combination chemotherapy conferred a more favorable response. CONCLUSIONS: These new insights derived from genomic profiling and immune phenotyping pave the way for rational immunotherapeutic interventions in NEBC patients, with the potential to ultimately reduce mortality from this otherwise fatal disease.

Estimating the viscoelastic anisotropy of human skin through high-frequency ultrasound elastography.

BACKGROUND: The skin is the largest organ of the human body and serves distinct functions in protecting the body. The viscoelastic properties of the skin play a key role in supporting the skin-healing process, also it may be changed due to some skin diseases. PROPOSE: In this study, high-frequency ultrasound (HFUS) elastography based on a Lamb wave model was used to noninvasively assess the viscoelastic anisotropy of human skin. METHOD: Elastic waves were generated through an external vibrator, and the wave propagation velocity was measured through 40 MHz ultrafast HFUS imaging. Through the use of a thin-layer gelatin phantom, HFUS elastography was verified to produce highly accurate estimates of elasticity and viscosity. In a human study involving five volunteers, viscoelastic anisotropy was assessed by rotating an ultrasound transducer 360°. RESULTS: An oval-shaped pattern in the elasticity of human forearm skin was identified, indicating the high elastic anisotropy of skin; the average elastic moduli were 24.90 ± 6.63 and 13.64 ± 2.67 kPa along and across the collagen fiber orientation, respectively. The average viscosity of all the recruited volunteers was 3.23 ± 0.93 Pa·s. CONCLUSIONS: Although the examined skin exhibited elastic anisotropy, no evident viscosity anisotropy was observed.

Enhancing and sustaining arsenic removal in a zerovalent iron-based magnetic flow-through water treatment system.

In areas affected by arsenicosis, zerovalent iron (ZVI)/sand filters are extensively used by households to treat groundwater, but ZVI surface passivation and filter clogging limit their arsenic (As) removal performance. Here we present a magnetic confinement-enabled column reactor coupled with periodic ultrasonic depassivation (MCCR-PUD), which efficiently and sustainably removes As by reaction with continuously generated iron (oxyhydr)oxides from ZVI oxidative corrosion. In the MCCR, ZVI microparticles self-assemble into stable millimeter-scale wires in forest-like arrays in a parallel magnetic field (0.42-0.48 T, produced by two parallel permanent magnets), forming a highly porous structure (87 % porosity) with twice the accessible reactive surface area of a ZVI/sand mixture. For a feed concentration of 100 µg/L As(III), the MCCR-PUD, with a short empty bed contact time (1.6 min), treated ca. 7340 empty bed volume (EBV) of water at breakthrough (10 µg/L), 9.4 folds higher than that of a ZVI/sand filter. Due to the large interspace between ZVI wires, the MCCR-PUD effectively prevented column clogging that occurred in the ZVI/sand filter. The high water treatment capacity was attributed to the much enhanced ZVI reactivity in the magnetic field, sustained through rejuvenation by PUD. Furthermore, most of As was structurally incorporated into the produced iron (oxyhydr)oxides (mostly ferrihydrite) in the MCCR-PUD, as revealed by Mössbauer spectroscopy, X-ray absorption spectroscopy, and sequential extraction experiments. This finding evinced a different mechanism from the surface adsorption in the ZVI/sand filter. The structural incorporation of As also resulted in much less As remobilization from the produced corrosion products during aging in water, in total ∼1 % in 28 days. Furthermore, the MCCR-PUD exihibted robust performance when treating complex synthetic groundwater containing natural organic matter and common ions (∼3700 EBV at breakthrough). Taken together, our study demonstrates the potential of the magnetic confinement-enabled ZVI reactor as a promising decentralized As treatment platform.

PRMT6-mediated ADMA promotes p62 phase separation to form a negative feedback loop in ferroptosis.

Purpose: Due to intrinsic defensive response, ferroptosis-activating targeted therapy fails to achieve satisfactory clinical benefits. Though p62-Keap1-Nrf2 axis is activated to form a negative feedback loop during ferroptosis induction, how p62 is activated remains largely unknown. Methods: MTS assay was applied to measure cell growth. Lipid ROS was detected with C11-BODIPY reagent by flow cytometer. Quantitative real-time PCR (qPCR) and western blotting were performed to determine mRNA and protein level. Immunofluorescence (IF) was performed to examine the distribution of proteins. Fluorescence recovery after photobleaching (FRAP) was adopted to evaluate p62 phase separation. Immunoprecipitation (IP), co-IP and Proximal ligation assay (PLA) were performed to detected protein posttranslational modifications and protein-protein interactions. Tumor xenograft model was employed to inspect in vivo growth of pancreatic cancer cells. Results: Upon ferroptosis induction, Nuclear Factor E2 Related Factor 2 (Nrf2) protein and its downstream genes such as HMOX1 and NQO1 were upregulated. Knockdown of p62 significantly reversed Nrf2 upregulation and Keap1 decrease after ferroptosis induction. Knockdown of either p62 or Nrf2 remarkably sensitized ferroptosis induction. Due to augmented p62 phase separation, formation of p62 bodies were increased to recruit Keap1 after ferroptosis induction. Protein arginine methyltransferase 6 (PRMT6) mediated asymmetric dimethylarginine (ADMA) of p62 to increase its oligomerization, promoting p62 phase separation and p62 body formation. Knockdown of p62 or PRMT6 notably sensitized pancreatic cancer cells to ferroptosis both in vitro and in vivo through suppressing Nrf2 signaling. Conclusion: During ferroptosis induction, PRMT6 mediated p62 ADMA to promote its phase separation, sequestering Keap1 to activate Nrf2 signaling and inhibit ferroptosis. Therefore, targeting PRMT6-mediated p62 ADMA could be a new option to sensitize ferroptosis for cancer treatment.

An Insulin-Modified pH-Responsive Nanopipette Based on Ion Current Rectification.

The properties of nanopipettes largely rely on the materials introduced onto their inner walls, which allow for a vast extension of their sensing capabilities. The challenge of simultaneously enhancing the sensitivity and selectivity of nanopipettes for pH sensing remains, hindering their practical applications. Herein, we report insulin-modified nanopipettes with excellent pH response performances, which were prepared by introducing insulin onto their inner walls via a two-step reaction involving silanization and amidation. The pH response intensity based on ion current rectification was significantly enhanced by approximately 4.29 times when utilizing insulin-modified nanopipettes compared with bare ones, demonstrating a linear response within the pH range of 2.50 to 7.80. In addition, insulin-modified nanopipettes featured good reversibility and selectivity. The modification processes were monitored using the I-V curves, and the relevant mechanisms were discussed. The effects of solution pH and insulin concentration on the modification results were investigated to achieve optimal insulin introduction. This study showed that the pH response behavior of nanopipettes can be greatly improved by introducing versatile molecules onto the inner walls, thereby contributing to the development and utilization of pH-responsive nanopipettes.

A novel NAC transcription factor ZmNAC55 negatively regulates drought stress in Zea mays.

Drought stress is a major limit on the maize growth and productivity, and understanding the drought response mechanism is one of the important ways to improve drought resistance in maize. However, more drought-related genes and their regulated mechanisms are still to be reported. Here, we identified a novel NAC transcription factor ZmNAC55 in Zea mays and comprehensively investigated the functions of ZmNAC55 under drought stress. ZmNAC55 belonged to the NAP subfamily. ZmNAC55 had a conserved NAC domain in the N-terminal region and a divergent TAR region in the C-terminal region. ZmNAC55 was a nuclear protein, and ZmNAC55 and its TAR region had the transcriptional activation activity. Furthermore, the expression level of ZmNAC55 in leaves could be highly induced by drought stress. ZmNAC55 overexpression in Arabidopsis conferred the drought-sensitive phenotype with higher water loss, lower survival rate, higher membrane ion leakage, and higher expression levels of some drought-related genes. Meanwhile, ZmNAC55 underexpression in maize enhanced drought tolerance with lower water loss, higher survival rate, lower membrane ion leakage and lower expression levels of some drought-related genes. In addition, ZmNAC55 appeared to be very key in regulating ROS production under drought stress. Moreover, ZmNAC55 could activate ZmHOP3 expression by binding to its promoter. A novel working model of ZmNAC55 under drought stress could be found in maize. Taken together, the NAC transcription factor ZmNAC55 could negatively regulate drought stress via increasing ZmHOP3 expression in maize. ZmNAC55 is a promising candidate for improving drought resistance in maize.

Emergence of plasmid-mediated tigecycline resistance tet(X4) gene in Enterobacterales isolated from wild animals in captivity.

Background: Over the past few decades, antimicrobial resistance (AMR) has emerged as a global health challenge in human and veterinary medicine. Research on AMR genes in captive wild animals has increased. However, the presence and molecular characteristics of tet(X)-carrying bacteria in these animals remain unknown. Methods: Eighty-four samples were collected from captive wild animals. tet(X) variants were detected using polymerase chain reaction and the isolates were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. All isolated strains were subjected to antimicrobial susceptibility testing and whole-genome sequencing. The virulence of an Escherichia coli strain carrying enterotoxin genes was assessed using a Galleria mellonella larval model. Results: We isolated two tet(X4)-positive E. coli strains and one tet(X4)-positive Raoultella ornithinolytica strain. Antimicrobial susceptibility tests revealed that all three tet(X4)-carrying bacteria were sensitive to the 13 tested antimicrobial agents, but exhibited resistance to tigecycline. Notably, one tet(X4)-carrying E. coli strain producing an enterotoxin had a toxic effect on G. mellonella larvae. Whole-genome sequencing analysis showed that the two tet(X4)-carrying E. coli strains had more than 95% similarity to tet(X4)-containing E. coli strains isolated from pigs and humans in China. Conclusion: The genetic environment of tet(X4) closely resembled that of the plasmid described in previous studies. Our study identified tet(X4)-positive strains in wildlife and provided valuable epidemiological data for monitoring drug resistance. The identification of enterotoxin-producing E. coli strains also highlights the potential risks posed by virulence genes.

D-dimer levels predict the treatment efficacy and prognosis of esophageal squamous cell carcinoma treated with PD-1/PD-L1 inhibitors.

OBJECTIVES: This study aimed to explore the value of D-dimer levels in predicting the treatment efficacy and prognosis of advanced esophageal squamous cell carcinoma (ESCC) treated with programmed cell death protein-1/programmed death-ligand 1 (PD-1/PD-L1) inhibitors. METHODS: The study retrospectively analyzed 233 ESCC patients who received PD-1/PD-L1 inhibitors. The optimal cut-off values for platelets, fibrinogen, and D-dimer were calculated based on maximally selected rank statistics for patients' overall survival. Univariate and multivariate analyses of progression-free survival and overall survival were conducted by Cox proportional hazards regression model. Subgroup analyses of D-dimer levels in different fibrinogen levels were performed by log-rank test. RESULTS: The multivariate Cox regression analyses demonstrated that ESCC patients with D-dimer levels > 236 ng/mL exhibited both poorer progression-free survival (P = 0.004) and overall survival (P < 0.0001) compared to those with low D-dimer levels. The subgroup analyses further indicated that in the group of low fibrinogen levels, the higher D-dimer levels of ESCC patients exhibited significantly shorter progression-free survival (P = 0.0021) and overall survival (P < 0.0001). CONCLUSIONS: The study revealed that the D-dimer levels possess predictive value for the treatment efficacy and prognosis of ESCC patients treated with PD-1/PD-L1 inhibitors.

Recognition of small water bodies under complex terrain based on SAR and optical image fusion algorithm.

Understanding the spatial and temporal distribution of small water bodies is essential for managing water resources, crafting conservation policies, and preserving watershed ecosystems and biodiversity. However, existing studies often rely on a single remote sensing data source (optical or microwave), focusing on large-scale, flat areas and lacking comprehensive monitoring of small water bodies in complex terrain. Therefore, considering the complementary advantages of multisource remote sensing (multispectral and SAR), this paper proposes a multispectral and SAR fusion algorithm, named Multispectral and SAR Fusion algorithm (MASF), to better capture the remote sensing characteristics of small water bodies in complex areas. Based on this, a dataset containing spectral, texture, and geometric features is constructed, and multi-scale segmentation and random forest algorithms are applied for identification of small water bodies in complex terrain. The results demonstrate that the proposed fusion algorithm MASF exhibits minimal spectral distortion (SAM < 3.5, ERGAS <21, RMSE <0.01) and robust spatial feature enhancement (PSNR >40, SSIM >0.999, CC > 0.99). The Overall Accuracy (OA) and Kappa coefficients for both experimental areas surpassed 0.9. For rivers and reservoirs, both Producer's Accuracy (PA) and User's Accuracy (UA) exceeded 0.9. The UA for agricultural ponds exceeded 0.8. Comparative analysis with three other types of water-related data products shows that the freshwater identification results in this study have certain advantages in local small water bodies. Our research holds significant implications for the utilization of water resources in mountainous areas, prevention and control of floods and floods, as well as the development of aquaculture industry.

Coinfecting phages impede each other's entry into the cell.

The developmental choice made by temperate phages, between cell death (lysis) and viral dormancy (lysogeny), is influenced by the relative abundance of viruses and hosts in the environment. The paradigm for this abundance-driven decision is phage lambda of E. coli, whose propensity to lysogenize increases with the number of viruses coinfecting the same bacterium. It is believed that lambda uses this number to infer whether phages or bacteria outnumber each other. However, this interpretation is premised on an accurate mapping between the extracellular phage-to-bacteria ratio and the intracellular multiplicity of infection (MOI). Here, we show this premise to be faulty. By simultaneously labeling phage capsids and genomes, we find that, while the number of phages landing on each cell reliably samples the population ratio, the number of phages entering the cell does not. Single-cell infections, performed in a microfluidic device and interpreted using a stochastic model, reveal that the probability and rate of phage entry decrease with the number of adsorbed phages. This decrease reflects an MOI-dependent perturbation to host physiology caused by phage attachment, as evidenced by compromised membrane integrity and loss of membrane potential. The dependence of entry dynamics on the surrounding medium results in a strong impact on the infection outcome, while the protracted entry of coinfecting phages increases the heterogeneity in infection outcome at a given MOI. Our findings in lambda, and similar results we obtained for phages T5 and P1, demonstrate the previously unappreciated role played by entry dynamics in determining the outcome of bacteriophage infection.

Wafer-Scale Patterning Integration of Chiral 3D Perovskite Single Crystals toward High-Performance Full-Stokes Polarimeter.

Chiral three-dimensional (3D) perovskites exhibit exceptional optoelectronic characteristics and inherent chiroptical activity, which may overcome the limitations of low-dimensional chiral optoelectronic devices and achieve superior performance. The integrated chip of high-performance arbitrary polarized light detection is one of the aims of chiral optoelectronic devices and may be achieved by chiral 3D perovskites. Herein, we first fabricate the wafer-scale integrated full-Stokes polarimeter by the synergy of unprecedented chiral 3D perovskites (R/S-PyEA)Pb2Br6 and one-step capillary-bridge assembly technology. Compared with the chiral low-dimensional perovskites, chiral 3D perovskites present smaller exciton binding energies of 57.3 meV and excellent circular dichroism (CD) absorption properties, yielding excellent circularly polarized light (CPL) photodetectors with an ultrahigh responsivity of 86.7 A W-1, an unprecedented detectivity exceeding 4.84 × 1013 Jones, a high anisotropy factor of 0.42, and high-fidelity CPL imaging with 256 pixels. Moreover, the anisotropic crystal structure also enables chiral 3D perovskites to have a large linear-polarization response with a polarized ratio of 1.52. The combination of linear-polarization and circular-polarization discrimination capabilities guarantees the achievement of a full-Stokes polarimeter. Our study provides new research insights for the large-scale patterning wafer integration of high-performance chiroptical devices.

Quantifying Chemical Reactions and Interfacial Properties at Buried Polymer/Polymer Interfaces.

Maleic anhydride (MAH)-modified polymers are used as tie layers for binding dissimilar polymers in multilayer polymer films. The MAH chemistry which promotes adhesion is well characterized in the bulk; however, only recently has the interfacial chemistry been studied. Sum frequency generation vibrational spectroscopy (SFG) is an interfacial spectroscopy technique which provides detailed information on interfacial chemical reactions, species, and molecular orientations and has been essential for characterizing the MAH chemistry in both nylon and ethyl vinyl alcohol copolymer (EVOH) model systems and coextruded multilayer films. Here, we further characterize the interfacial chemistry between MAH-modified polyethylene tie layers and both EVOH and nylon by investigating the model systems over a range of MAH concentrations. We can detect the interfacial chemical reaction products between MAH and the barrier layer at MAH concentrations of ≥0.022 wt % for nylon and ≥0.077 wt % for EVOH. Additionally, from the concentration-dependent reaction reactant/product SFG peak positions and the product imide or ester/acid C═O group tilt angles extracted from the polarization-dependent SFG spectra, we quantitatively observe concentration-dependent changes to both the interfacial chemistry and interfacial structure. The interfacial chemistry and molecular orientation as a function of MAH concentration are well correlated with the adhesion strength, providing important quantitative information for the future design of MAH-modified tie layers for a variety of important applications.

Molecular behavior of silicone adhesive at buried polymer interface studied by molecular dynamics simulation and sum frequency generation vibrational spectroscopy.

Silicones have excellent material properties and are used extensively in many applications, ranging from adhesives and lubricants to electrical insulation. To ensure strong adhesion of silicone adhesives to a wide variety of substrates, silane-based adhesion promotors are typically blended into the silicone adhesive formulation. However, little is known at the molecular level about the true silane adhesion promotion mechanism, which limits the ability to develop even more effective adhesion promoters. To understand the adhesion promotion mechanism of silane molecules at the molecular level, this study has used sum frequency generation vibrational spectroscopy (SFG) to determine the behavior of (3-glycidoxypropyl)trimethoxy silane (γ-GPS) at the buried interface between poly(ethylene terephthalate) (PET) and a bulk silicone adhesive. To complement and extend the SFG results, atomistic molecular dynamics (MD) simulations were applied to investigate molecular behavior and interfacial interaction of γ-GPS at the silicone/PET interface. Free energy computations were used to study the γ-GPS interaction in the sample system and determine the γ-GPS interfacial segregation mechanism. Both experiments and simulations consistently show that γ-GPS molecules prefer to segregate at the interface between PET and PDMS. The methoxy groups on γ-GPS molecules orient toward the PDMS polymer phase. The consistent picture of interfacial structure emerging from both simulation and experiment provides enhanced insight on how γ-GPS behaves in the silicone - PET system and illustrates why γ-GPS could improve the adhesion of silicone adhesive, leading to further understanding of silicone adhesion mechanisms useful in the design of silicone adhesives with improved performance.

Terpene synthases GhTPS6 and GhTPS47 participate in resistance to Verticillium dahliae in upland cotton.

Terpene synthases (TPSs) are enzymes responsible for catalyzing the production of diverse terpenes, the largest class of secondary metabolites in plants. Here, we identified 107 TPS gene loci encompassing 92 full-length TPS genes in upland cotton (Gossypium hirsutum L.). Phylogenetic analysis showed they were divided into six subfamilies. Segmental duplication and tandem duplication events contributed greatly to the expansion of TPS gene family, particularly the TPS-a and TPS-b subfamilies. Expression profile analysis screened out that GhTPSs may mediate the interaction between cotton and Verticillium dahliae. Three-dimensional structures and subcellular localizations of the two selected GhTPSs, GhTPS6 and GhTPS47, which belong to the TPS-a subfamily, demonstrated similarity in protein structures and nucleus and cytoplasm localization. Virus-induced gene silencing (VIGS) of the two GhTPSs yielded plants characterized by increased wilting and chlorosis, more severe vascular browning, and higher disease index than control plants. Additionally, knockdown of GhTPS6 and GhTPS47 led to the down-regulation of cotton terpene synthesis following V. dahliae infection, indicating that these two genes may positively regulate resistance to V. dahliae through the modulation of disease-resistant terpene biosynthesis. Overall, our study represents a comprehensive analysis of the G. hirsutum TPS gene family, revealing their potential roles in defense responses against Verticillium wilt.