Amphiphilic nanofibrillated cellulose/polyurethane composites with antibacterial, antifouling and self-healing properties for potential catheter applications.

This study focuses on enhancing interventional medical devices, specifically catheters, using a novel composite material. Challenges like corrosion and contamination in vivo, often caused by body fluids' pH, bacteria, and proteins, lead to mechanical damage, bacterial colonization, and biofilm formation on devices like catheters. The objective of this study was to prepare a versatile composite (HFs) by designing polyurethanes (HPU) with an ionic chain extender (HIID) and blending them with amphiphilic nanofibrillated cellulose (Am-CNF). The composite leverages dynamic interactions such as hydrogen bonding and electrostatic forces, as evidenced by Molecular Mechanics (MM) calculations. The H4F0.75 composite exhibited exceptional properties: 99 % length recovery post 600 stretching cycles at 100 % strain, rapid self-healing in artificial urine, high bactericidal activity, and excellent cell viability. Moreover, mechanical aging tests and UV-vis spectral analysis confirmed the material's durability and safety. These findings suggest that the HFs composite holds significant promise for improving catheters' performance in medical applications.

Super-tough polylactic acid (PLA)/poly(butylene succinate) (PBS) materials prepared through reactive blending with epoxy-functionalized PMMA-GMA copolymer.

High-performance biosourced polylactic acid (PLA)/poly(butylene succinate) (PBS) blends with small amounts of compatibilizer, epoxy-functionalized methyl methacrylate-co-glycidyl methacrylate copolymer (PMMA-GMA), were fabricated by melt compounding. The properties of the modified PLA/PMMA-GMA, PBS/PMMA-GMA, and PLS(PLA/PBS)/PMMA-GMA blends were investigated systematically. DSC combined with X-ray diffraction revealed a low-order semi-crystalline structure for all samples. SEM and DMA showed that the compatibility between PLA and PBS was improved after addition of PMMA-GMA. Rheological behavior of blends showed that the addition of PMMA-GMA resulted in a significant improvement in the viscoelasticity. FT-IR spectra confirmed that the interfacial compatibilization between PLA and PBS phases was improved due to the reaction of epoxy groups with terminal groups of PLA and PBS. Finally, the toughness and notched impact strength of the PLA materials were increased significantly. The elongation at break and notched impact strength of PLS/PMMA-GMA was about 55.7 and 6.2 times than neat PLA after incorporation of 7 wt% PMMA-GMA, respectively.

Investigation of the spatial and temporal variation of soil salinity using Google Earth Engine: a case study at Werigan-Kuqa Oasis, West China.

Large-scale soil salinity surveys are time-costly and labor-intensive, and it is also more difficult to investigate historical salinity, while in arid and semi-arid regions, the investigation of the spatial and temporal characteristics of salinity can provide a scientific basis for the scientific prevention of salinity, With this objective, this study uses multi-source data combined with ensemble learning and Google Earth Engine to build a monitoring model to observe the evolution of salinization in the Werigan-Kuqa River Oasis from 1996 to 2021 and to analyze the driving factors. In this experiment, three ensemble learning models, Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LightGBM), were established using data collected in the field for different years and some environmental variables, After the accuracy validation of the model, XGBoost had the highest accuracy of salinity prediction in this study area, with RMSE of 17.62 dS m-1, R2 of 0.73 and RPIQ of 2.45 in the test set. In this experiment, after Spearman correlation analysis of soil Electrical Conductivity (EC) with environmental variables, we found that the near-infrared band in the original band, the DEM in the topographic factor, the vegetation index based on remote sensing, and the salinity index soil EC had a strong correlation. The spatial distribution of salinization is generally characterized by good in the west and north and severe in the east and south. Non-salinization, light salinization, and moderate salinization gradually expanded southward and eastward from the interior of the western oasis over 25 years. Severe and very severe salinization gradually shifted from the northern edge of the oasis to the eastern and southeastern desert areas during the 25 years. The saline soils with the highest salinity class were distributed in most of the desert areas in the eastern part of the Werigan-Kuqa Oasis study area as well as in smaller areas in the west in 1996, shrinking in size and characterized by a discontinuous distribution by 2021. In terms of area change, the non-salinized area increased from 198.25 in 1996 to 1682.47 km2 in 2021. The area of saline soil with the highest salinization level decreased from 5708.77 in 1996 to 2246.87 km2 in 2021. overall, the overall salinization of the Werigan-Kuqa Oasis improved.

Quantifying the effects of human activities and climate variability on runoff changes using variable infiltration capacity model.

Detecting and assessing changes in the hydrologic cycle and its response to a changing environment is essential for maintaining regional ecological security and restoring degraded ecosystems. There is no clear scientific evidence on the effects of human activities and climate variability on runoff and its components in typical arid areas. Therefore, in this study, a heuristic segmentation algorithm, a variable infiltration capacity model (VIC), and remote sensing data to quantify the effects of human activities and climate variability on runoff in the catchment of Lake Ebinur, Xinjiang, China. The results found: (1) The heuristic segmentation algorithm divided the study period into reference period (1964-1985) and two impact periods: I (1986-2000) and II (2001-2017). (2) Cropland and forest land showed an increasing trend, with grassland and barren land accounting for most of the increase. At the same time, the leaf area index (LAI) increased by 0.002 per year during the growing season. (3) Compared with the reference period, runoff depth decreased by 108.80 mm in impact period I due to human activities, but increased by 110.5 mm due to climate variability, resulting in an overall increase in runoff depth of 1.72 mm. Runoff depth increased by 11.10 mm in the impact period II compared to the reference period, with climate variability resulting in an increase of 154.40 mm, but human activities resulted in a decrease of 143.30 mm. Our results shed light on decision-making related to water stress in changing circumstances in arid regions.

Morphological Evolution and Damping Properties of Dynamically Vulcanized Butyl Rubber/Polypropylene Thermoplastic Elastomers.

We successfully prepared butyl rubber (IIR)/polypropylene (PP) thermoplastic vulcanizate (IIR/PP-TPV) for shock-absorption devices by dynamic vulcanization (DV) using octyl-phenolic resin as a vulcanizing agent and studied the morphological evolution and properties during DV. We found that the damping temperature region of the IIR/PP-TPV broadened with the disappearance of the glass transition temperature (Tg) in the PP phase, which is ascribed to the improvement of compatibility between the IIR and PP with increasing DV time. As DV progresses, the size of the dispersed IIR particles and the PP crystalline phase decreases, leading to the formation of a sea-island morphology. After four cycles of recycling, the retention rates of tensile strength and elongation at break of the IIR/PP-TPV reached 88% and 86%, respectively. The size of the IIR cross-linking particles in the IIR/PP-TPV becomes larger after melt recombination, and the continuous PP phase provides excellent recyclability. Significantly, the prepared IIR/PP-TPV exhibits excellent recyclability, high elasticity, and good damping property.

In-situ reaction compatibilization modification of poly(butylene succinate-co-terephthalate)/polylactide acid blend films by multifunctional epoxy compound.

Poly(butylene succinate-co-terephthalate) (PBST) copolyester, is a new type of biodegradable synthetic polymer material that has emerged in recent years, but it cannot meet the market requirements, because of its low strength. The high-strength and high-modulus polylactic acid (PLA) was blended with PBST to increase its strength, and the chain extender ADR-4370 was used to modify PBST/PLA films by reaction and compatibilization. Compared with the 80/20 wt% PBST/PLA films, the tensile strength after modification with 0.3 wt% ADR was increased by 21.8 % and 44.3 % in the machine direction (MD) and in the transverse direction (TD), respectively. The Water Vapor Permeability (WVP) was decreased from 10.0 × 10-14 to 3.09 × 10-14 g·cm/cm2·s·Pa. The compatibilization mechanism was studied by gel permeation chromatography, infrared spectroscopy, dynamic mechanical analysis, rheological analysis, and other characterization methods. The formation of the copolymer PLA-g-PBST is the most important factor to improve the compatibility of the system and the mechanical properties of the films.

Estimation of Soil Organic Carbon Content in the Ebinur Lake Wetland, Xinjiang, China, Based on Multisource Remote Sensing Data and Ensemble Learning Algorithms.

Soil organic carbon (SOC), as the largest carbon pool on the land surface, plays an important role in soil quality, ecological security and the global carbon cycle. Multisource remote sensing data-driven modeling strategies are not well understood for accurately mapping soil organic carbon. Here, we hypothesized that the Sentinel-2 Multispectral Sensor Instrument (MSI) data-driven modeling strategy produced superior outcomes compared to modeling based on Landsat 8 Operational Land Imager (OLI) data due to the finer spatial and spectral resolutions of the Sentinel-2A MSI data. To test this hypothesis, the Ebinur Lake wetland in Xinjiang was selected as the study area. In this study, SOC estimation was carried out using Sentinel-2A and Landsat 8 data, combining climatic variables, topographic factors, index variables and Sentinel-1A data to construct a common variable model for Sentinel-2A data and Landsat 8 data, and a full variable model for Sentinel-2A data, respectively. We utilized ensemble learning algorithms to assess the prediction performance of modeling strategies, including random forest (RF), gradient boosted decision tree (GBDT) and extreme gradient boosting (XGBoost) algorithms. The results show that: (1) The Sentinel-2A model outperformed the Landsat 8 model in the prediction of SOC contents, and the Sentinel-2A full variable model under the XGBoost algorithm achieved the best results R2 = 0.804, RMSE = 1.771, RPIQ = 2.687). (2) The full variable model of Sentinel-2A with the addition of the red-edge band and red-edge index improved R2 by 6% and 3.2% over the common variable Landsat 8 and Sentinel-2A models, respectively. (3) In the SOC mapping of the Ebinur Lake wetland, the areas with higher SOC content were mainly concentrated in the oasis, while the mountainous and lakeside areas had lower SOC contents. Our results provide a program to monitor the sustainability of terrestrial ecosystems through a satellite perspective.

A Composite of Two Dimensional GeSe2 /Nitrogen-Doped Reduced Graphene Oxide for Enhanced Capacitive Lithium-Ion Storage.

A composite of two-dimensional (2D) GeSe2 nanosheets dispersed on N-doped reduced graphene oxide (GeSe2 /N-rGO) is fabricated via a simple hydrothermal method combined with post-selenization process. The high electronic conductivity and the substantial void spaces of the wrinkled N-rGO can improve the electrical conductivity of the active material and accommodate the volume evolution of GeSe2 nanosheets during the (de)lithiation processes, while GeSe2 nanosheets can reduce ion diffusion length effectively. Meanwhile, the unique layered structure is beneficial to the contact of the active material and electrolyte, and the reversibility of conversion reaction has also been improved. Furthermore, kinetics analysis reveals a pseudocapacitance-dominated Li+ -storage mechanism at high rates. In-situ X-ray diffraction analysis discloses that the conversion reaction has played a certain part in Li+ -storage. Thus, the GeSe2 /N-rGO composite delivers excellent rate capability and good long-term stability with a high reversible capacity of 711.0 mA h g-1 after 2000 cycles at 1 A g-1 .

Poly (lactic acid) blends with excellent low temperature toughness: A comparative study on poly (lactic acid) blends with different toughening agents.

Poly (lactic acid) (PLA) blends with different toughening agents were prepared by melt compounding, and the effects of toughening agents on the toughness of PLA, especially the low-temperature toughness, were investigated. All blends were immiscible systems, but the rheological Cole-Cole diagram showed that the blends had certain compatibility, and the interfacial bonding of PLA/Ethylene/butyl methacrylate/Glycidyl Methacrylate Terpolymer (GEBMA) blend was the best. With addition of the toughening agents, all blends showed improvement of the tensile and impact toughness both at room temperature and low temperature. GEBMA was the best toughening agent, the elongation at break and impact strength at room temperature and low temperature were greatly improved. The elongation at break, tensile strength and impact strength of PLA blend with 20 wt% GEBMA at -20 °C was 55.8 MPa, 195.9% and 18.8 kJ/m2, respectively, which showed the reinforcement and super ductility at low temperature. However, the toughening effect of Poly (propylene carbonate) polyurethane (PPCU) at low temperature was poor. The Tg and interfacial bonding were the main factors affecting the toughness of the blends, especially at low temperature. The lower the Tg and the better the interfacial bonding, the better the toughness of the blends.

Improvement of the strength and toughness of biodegradable polylactide/silica nanocomposites by uniaxial pre-stretching.

Highly toughened polylactide (PLA) nanocomposites with balanced stiffness and strength were successfully prepared by combining the modification of 5 wt% silica (SiO2) nanoparticles and uniaxial pre-stretching. The PLA/5 wt% SiO2 nanocomposites fractured in a brittle way due to the network structure composed of cohesional entanglements. After pre-stretching, the elongation at break was increased to 168% at pre-stretching ratio (PSR) of only 0.5, which should be attributed to the destruction of the network structure of cohesional entanglements. With the increment of PSR, the modulus and tensile strength were improved obviously (2725 MPa, 101.6 MPa at PSR = 2.0) while the elongation at break (56% at PSR = 2.0) reduced gradually because of the formation of orientation and mesophase. However, the elongation at break was still larger than that of undrawn PLA (5.4%) and undrawn PLA nanocomposites (7.2%), indicating that the uniaxial pre-stretching was an effect way to strengthen and toughen PLA nanocomposites.

Preparation and properties of poly(L-lactic acid) blends with excellent low-temperature toughness by blending acrylic ester based impact resistance agent.

Poly(L-lactic acid) (PLLA) blends with excellent low-temperature toughness and strength were prepared by melt compounding with acrylic ester based impact resistance agent (AEIR). The morphology, thermal properties, mechanical properties and biodegradability of the blends were investigated. Morphology observations revealed the blend was immiscible but had good compatibility with the dispersed phase size of about 200-300 nm. With the addition of AEIR, dramatic improvement in toughness of PLLA was achieved in a wide temperature range, especially at low temperatures the tensile strength was effectively remained. For the blend with 20 wt% AEIR, the tensile strength, elongation at break and impact strength were 51.6 MPa, 72% and 77.1 KJ/m2 at -20 °C, respectively, much greater than that reported. The calculated Tg of AEIR was lower than the test temperatures, and the brittle-tough transition occurred. The PLLA matrix demonstrated obvious shear yielding which induced energy dissipation and therefore lead to excellent toughness of the blends. Moreover, the biodegradation of PLLA was enhanced after blends preparation.

Fiber-induced crystallization in polymer composites: A comparative study on poly(lactic acid) composites filled with basalt fiber and fiber powder.

The poly(lactic acid) (PLA) composites with the silane coupling agent treated basalt fiber (SBF) and basalt fiber powder (SBFP) were prepared. The crystalline morphology, mechanical properties, and heat resistance of PLA/SBF/SBFP composites were investigated. The results indicated that SBF or SBFP not only acted as heterogeneous nucleating agents for PLA crystallization but also improved the mechanical properties and heat resistance of PLA. Morphological analyses showed that SBFP could play nucleating role to reduce the spherulites size of PLA, and SBF could restrict the mobility of PLA chains and construct interface crystallization for PLA during isothermal crystallization process. The composites with higher SBF loading, the "Transcrystalline-network" built in the composites significantly improved the heat resistance properties of PLA. Due to the synergistic effect of SBF and SBFP, the PLA/SBF/SBFP composites showed high heat deformation temperature (HDT), especially after isothermal crystallization, the HDT increased to 150.5 °C for the PLA/SBF/SBFP 50/10/40 composite, much higher (about 190%) than that of pure PLA (71.7 °C).

Stable Li-ion storage in Ge/N-doped carbon microsphere anodes.

The development of environmentally benign, low-cost and high-performance Ge-based materials for lithium-ion batteries (LIBs) has remained a great challenge. Herein, the synthesis of Ge/N-doped carbon microspheres (Ge/NC) is firstly performed using N-(2hydroxyethyl)ethylenediamine (AEEA) and ethanediamine (EDA) as solvents, ligands and carbon sources. The three-dimensional Ge/NC microspheres prepared with AEEA (Ge/NC-A) are constructed from nanosheets with a thickness of about 20 nm. Such a hierarchically structured material not only allowed sufficient contact between the nanosheets and electrolyte, but also provided sufficient void space and uniform conductive sites. At the same time, N-doped carbon in the Ge/NC-A microspheres can greatly improve the electrical conductivity and the structural stability. This material exhibited a superior rate performance (633.1 mA h g-1 at 20 A g-1), favorable reversible capacity (1113.2 mA h g-1 at 0.2 A g-1) and good cycling stability (a high reversible capacity of 965.0 mA h g-1 after 1000 cycles) when examined as an anode for LIBs. A full cell was fabricated using Ge/NC-A as an anode and LiFePO4 as a cathode and delivered a capacity of 100.7 mA h g-1 after 100 cycles. Furthermore, the lithiation/delithiation mechanisms in the Ge/NC-A microspheres were revealed by in situ Raman and in situ XRD measurements, indicating that the crystalline Ge was firstly converted into amorphous Li-Ge phases and transformed into amorphous Ge during the discharge/charge process. Therefore, the repeated transition between the amorphous and crystalline phases can be avoided, thus improving the cycling stability.

Preparation of graphene/polypropylene composites with high dielectric constant and low dielectric loss via constructing a segregated graphene network.

In this paper, a reduced graphene oxide/polypropylene (rGO/PP) dielectric composite with high dielectric constant and low dielectric loss at a low filler content was prepared via constructing a segregated moderately-reduced graphene network by encapsulation of GO on PP latex particles and subsequent in situ reduction of GO by hydrazine hydrate. GO/PP latex was prepared through artificial PP latex preparation in the presence of GO based on the solution-emulsification technique. As the emulsification proceeded, GO could self-assemble to become encapsulated on the surface of PP latex particles composed of PP and maleic-anhydride-grafted-PP because of the hydrogen bonding interaction between maleic-anhydride-grafted-PP and GO nanosheets. After reduction, the rGO encapsulated PP latex particles were obtained, and after coagulation and hot pressing, a segregated graphene network was achieved at a low content of rGO, demonstrated by TEM images. The dielectric constant at 1 kHz obviously increased from 3.28 for PP to 55.8 for the composite with 1.5 wt% rGO. The dielectric loss of the composite was retained at a low value (1.04). This study provides a new simple and effective strategy for preparing high-performance dielectric composites with high dielectric constant and low dielectric loss, facilitating the wide application of dielectric materials.

Template-free fabrication of 1D core-shell MoO2@MoS2/nitrogen-doped carbon nanorods for enhanced lithium/sodium-ion storage.

A universal anode material of 1D core-shell MoO2@MoS2/nitrogen-doped carbon (MoO2@MoS2/NC) nanorods has been elaborately synthesized via a facile fabrication route for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), in which MoO2 core not only acts as a conductive backbone for efficient electron transport, but creates structural disorders in MoS2 nanosheets to prevent aggregation and expose more active sites for alkali-ions. Meanwhile, the MoO2 core is tightly encapsulated by the parallelly aligned MoS2 nanosheets to constrain the size of crystals, which greatly shortens the ionic diffusion path and accelerates diffusion rate, thus ensuring fast reaction kinetics. Additionally, the resilient and conductive N-doped carbon matrix in the hybrid could maintain the structural integrity and enhance the electrical conductivity of the electrodes, improving the rate capability and life span. The flexible 1D nanorods could contract freely during the charge/discharge process, further assuring the structural stability of the electrodes. Benefiting from the above-mentioned advantages, the MoO2@MoS2/NC electrodes still remains a specific capacity of 583.5 mA h g-1 after 1500 cycles at a high current density up to 10 A g-1 in LIBs, and a capacity of 419.8 mA h g-1 is steadily kept over 800 cycles at 2 A g-1 in SIBs.

General Synthesis of Sulfonate-Based Metal-Organic Framework Derived Composite of Mx Sy @N/S-Doped Carbon for High-Performance Lithium/Sodium Ion Batteries.

A general and simple strategy is realized for the first time for the preparation of metal sulfide (Mx Sy ) nanoparticles immobilized into N/S co-doped carbon (NSC) through a one-step pyrolysis method. The organic ligand 1,5-naphthalenedisulfonic acid in the metal-organic framework (MOF) precursor is used as a sulfur source, and metal ions are sulfurized in situ to form Mx Sy nanoparticles, resulting in the formation of Mx Sy /NSC (M=Fe, Co, Cu, Ni, Mn, Zn) composites. Benefiting from the Mx Sy nanoparticles and conductive carbon, a synergistic effect of the composite is achieved. For instance, the composite of Fe7 S8 /NSC as an anode displays excellent long-term cycling stability in lithium/sodium ion batteries. At 5 A g-1 , large capacities of 645 mA h g-1 and 426.6 mA h g-1 can be retained after 1500 cycles for the lithium-ion battery and after 1000 cycles for the sodium-ion battery, respectively.

Novel luminescent homo/heterometallic platinum(ii) alkynyl complexes based on Y-shaped pyridyl diphosphines.

A series of dinuclear platinum(ii) alkynyl complexes [Pt2L2(C[triple bond, length as m-dash]CC6H4R-4)4] (R = H 1, CH32, But3) and unusual tetranuclear Pt(ii)-Ag(i) clusters [Pt2Ag2L(C[triple bond, length as m-dash]CC6H4R-4)6] (R = H, 4; CH3, 5; But, 6), together with novel polymer crystals [Pt2Ag2L(C[triple bond, length as m-dash]CC6H5)6]∞ ([4]∞), were synthesized by a self-assembly reaction between [NBu4]2[Pt(C[triple bond, length as m-dash]CC6H4-R-4)4] and [Ag6L6]6+ (L = 4-(3,5-(diphenylphosphine)phenyl)pyridine). These complexes were characterized by using a range of spectroscopic techniques and complexes 1, 3, 5, and [4]∞ were analysed by X-ray crystallography. Each platinum atom of the Pt(ii)-Ag(i) clusters shows an unusual asymmetric distorted square planar geometry with three alkynyl groups and one bridging L phosphorus atom. Dinuclear complexes 1-3 demonstrate solid-state weak blue luminescence, while tetranuclear Pt(ii)-Ag(i) clusters 4-6 show intense blue-green or yellow-green emission. Furthermore, the crystalline samples of polymer [4]∞ display bright yellow emission (518 nm) that is significantly red-shifted as compared to monomer crystal 4.

Green and facile edge-oxidation of multi-layer graphene by sodium persulfate activated with ferrous ions.

Effective edge oxidation of graphene with high structural integrity is highly desirable yet technically challenging for most practical applications. In this work, we have developed a green and facile strategy to obtain edge-oxidized graphene with good dispersion stability and high electrical conductivity by exploiting high edge reactivity of highly conductive multi-layer graphene and oxidizing radicals (SO4 -˙) generated from sodium persulfate (Na2S2O8) with ferrous ion (Fe2+) activation. Owing to high structural integrity of pristine graphene and effective edge oxidation, the obtained edge-oxidized graphene exhibited excellent dispersion stability and satisfactory electrical conductivity (i.e. ≥240 S cm-1). Moreover, the oxidation degree of pristine graphene can be well controlled by adjusting treatment time. The obtained edge-oxidized graphene is expected to find a variety of applications in many fields of anti-static films, energy storage materials, flexible sensors and high-performance nanocomposites.

A hierarchical composite of GeO2 nanotubes/N-doped carbon microspheres with high-rate and super-durable performance for lithium-ion batteries.

A new composite of hierarchical microspheres assembled by GeO2 nanotubes/nitrogen doped carbon (GeO2/NCS) derived from organic germanium complexes has been fabricated for the first time, which exhibited a high capacity of 789 mA h g-1 at 1 A g-1 even after 500 cycles and good rate capability.

Ductile and biodegradable poly (lactic acid) matrix film with layered structure.

Polylactide (PLA), as a biodegradable packing material, has attracted plenty of attention. However, some problems still limit the application of PLA in packing industry such as the inherent brittleness and low crack propagation resistance. In order to overcome these challenges, we blended PLA with a reactive toughening agent (Ethylene-Acrylic ester-Glycidyl methacrylate terpolymer) during extrusion and film processing. The glycidyl methacrylate groups in toughening agent offered some sites to react with COOH and OH groups of PLA thus leaded to a great interfacial compatibility. The proper compatibility was the premise of adjusting the phase structure of blend and film based on different processing methods. The blend had a sea-island structure after melting extrusion and heat pressed technologies while film formed annular layer structure after film blowing. The structure determined properties. Both the toughness and melt strength of blends had been improved. Moreover, it was interesting to found that tear strength of film with 10% toughening agent dramatically increased to 197.8 KN/m and 137.7 KN/m in the transverse direction (TD) and in the machine direction (MD), respectively. Besides, the elongation at break of film could reach 242.2% in MD. This work exhibited that phase morphology was significant for mechanical performances.