High Thermal Conductivity and Radiative Cooling Designed Boron Nitride Nanosheets/Silk Fibroin Films for Personal Thermal Management.

The implementation of passive cooling strategies is crucial for transitioning from the current high-power- and energy-intensive thermal management practices to more environmentally friendly and carbon-neutral alternatives. Among the various approaches, developing thermal management materials with high thermal conductivity and emissivity for effective cooling of personal and wearable devices in both indoor and outdoor settings poses significant challenges. In this study, we successfully fabricated a cooling patch by combining biodegradable silk fibroin with boron nitride nanosheets. This patch exhibits consistent heat dissipation capabilities under different ambient conditions. Leveraging its excellent radiative cooling efficiency (Rsolar = 0.89 and εLWIR = 0.84) and high thermal conductivity (in-plane 27.58 W m-1 K-1 and out-plane 1.77 W m-1 K-1), the cooling patch achieves significant simulated skin temperature reductions of approximately 2.5 and 8.2 °C in outdoor and indoor conditions, respectively. Furthermore, the film demonstrates excellent biosafety and can be recycled and reused for at least three months. This innovative BNNS/SF film holds great potential for advancing the field of personal thermal management materials.

Anisotropic Black Phosphorene Structural Modulation for Thermal Storage and Solar-Thermal Conversion.

Exploiting novel strategies for simultaneously harvesting ubiquitous, renewable, and easily accessible solar energy based on the photothermal effect, and efficiently storing the acquired thermal energy plays a vital role in revolutionizing the current fossil fuel-dominating energy structure. Developing black phosphorene-based phase-change composites with optimized photothermal conversion efficiencyand high latent heat is the most promising way to achieve efficient solar energy harvesting and rapid thermal energy storage. However, exfoliating high-quality black phosphorene nanosheets  remains challenging, Furthermore, an efficient strategy that can construct the aligned black phosphorene frameworks to maximize thermal conductivity enhancement is still lacking. Herein, high-quality black phosphorene nanosheets are prepared by an optimized exfoliating strategy. Meanwhile, by regulating the temperature gradient during freeze-casting, the framework consisting of shipshape aligned black phosphorene at long-range is successfully fabricated, improving the thermal conductivity of the poly(ethylene glycol) matrix up to 1.81 W m-1  K-1 at 20 vol% black phosphorene loading. The framework also endows the composite with excellent phase-change material encapsulation capacity and  high latent heat of 103.91 J g-1 . It is envisioned that the work advances the paradigm of contrasting frameworks with nanosheets toward controllable structure thermal enhancement of the composites.

Preparation and Properties of Photoresponsive Pendimethalin@Silica-cinnamamide/γ-CD Microspheres for Pesticide Controlled Release.

Photocontrolled pesticide delivery systems have broad prospects for application in agriculture. Here, a novel photoresponsive herbicide delivery system was fabricated by functionalizing silica microsphere surfaces with cinnamamide and encapsulating the silica-cinnamamide with γ-cyclodextrin (γ-CD) to form a double-layered microsphere shell loaded with pendimethalin (pendimethalin@silica-cinnamamide/γ-CD). The microspheres showed remarkable loading capacity for pendimethalin (approximately 30.25% w/w) and displayed excellent photoresponsiveness and controlled release. The cumulative drug release rate exceeded 80% over 72 h under UV or sunlight irradiation. The herbicidal activity of the microspheres against Echinochloa crusgalli (L.) Beauv. was almost the same as that of pendimethalin under UV or sunlight. A bioactivity survey confirmed that the pendimethalin@silica-cinnamamide/γ-CD microspheres exhibited longer duration weed control than commercial pendimethalin. Allium cepa chromosomal aberration assays demonstrated that the microspheres showed lower genotoxicity than pendimethalin. These advantages indicate that pendimethalin@silica-cinnamamide/γ-CD microspheres constitute an environmentally friendly herbicidal formulation.

Ecohydrological effects of water conveyance in a disconnected river in an arid inland river basin.

Water system management is a worldwide challenge, especially in arid and semi-arid regions. Ecological water conveyance projects aim to raise the groundwater table, thereby saving natural vegetation and curbing ecological deterioration. Since 2000, these projects have been implemented in the arid zone of northwest China, with generally successful outcomes. Taking a portion of the lower reaches of the Tarim River as the study area, this paper analyzes in detail the ecohydrological effects which have occurred since the launching of artificial water conveyance 20 years ago. The results show that the groundwater table in the upper, middle and lower segments of the Tarim River's lower reaches has been raised on average 4.06, 4.83 and 5.13 m, respectively, while the area of surface water bodies connected to those sections has expanded from 49.00 km2 to 498.54 km2. At the same time, Taitema Lake, which is the terminal lake of the Tarim River, has been revived and now boasts a water area of 455.27 km2. Other findings indicate that the surface ecological response is extremely sensitive and that the area of natural vegetation has expanded to 1423 km2. Furthermore, the vegetation coverage, vegetation index (NDVI), and Net Primary Productivity (NPP) have increased by 132 km2, 0.07 and 7.6 g C m-2, respectively, and the Simpson dominance, McIntosh evenness, and Margalef richness indices have risen by 0.33, 0.35 and 0.49, respectively, in the monitored sample sites. As well, the carbon sink area has expanded from 1.54% to 7.8%. Given the increasing intensity of the occurrence of extreme hydrological events and successive dry years, similar ecological water conveyance projects should be considered elsewhere in China and in other parts of the world. The water conveyance scheme has generally proven successful and should be optimized to enhance the benefits of ecological water conveyance under water resource constraints.

Enhanced thermal transportation across an electrostatic self-assembly of black phosphorene and boron nitride nanosheets in flexible composite films.

For effective heat dissipation in portable electronics, there is a great demand for lightweight and flexible films with superior thermal transport properties. Despite extensive efforts, enhancing the intrinsic low thermal conductivity of polymers while simultaneously maintaining their flexibility is difficult to achieve due to the dilemma of quarrying appropriate filler loading. Herein, a cellulose nanofiber-based film with high in-plane thermal conductivity up to 72.53 W m-1 K-1 was obtained by harnessing the advantage of functionalized boron nitride nanosheets (f-BNNS) and black phosphorene (BP) via the vacuum filtration process. Besides, our unique design based on the electrostatic coupling of black phosphorene and functionalized boron nitride nanosheets significantly reduced the interfacial thermal resistance of the composite films. This work offers new insights into establishing a facile, yet efficient approach to preparing high thermal conductive heat spreaders.

[Hydrochemical Characteristics and Transformation Relationship of Surface Water and Groundwater in the Plain Area of Bortala River Basin, Xinjiang].

The geological conditions of the Bortala River basin are complex, and the transformation of surface water and groundwater is frequent. It is great significance to study the hydrochemical characteristics and transformation relationship of surface water and groundwater for the reasonable development and allocation of water resources in the basin. Based on 15 surface water samples and 39 groundwater samples collected in April and May 2021, the APCS/MLR model and the combination of stable hydrogen and oxygen isotopes with hydrochemistry were used in this study to analyze the hydrochemical types and the distribution characteristics of hydrogen and oxygen isotopes, the source contribution of chemical components, and the transformation relationship between surface water and groundwater. The results showed that the surface water was mainly HCO3·SO4-Ca type and HCO3-Ca type, and the groundwater was mainly HCO3·SO4-Ca·Na type, HCO3-Ca type, and HCO3·SO4-Ca type. The contribution rates of the dissolution-migration-enrichment factor, human activities factor, environment factor, and native geological factor to the chemical components were 28.8%, 17.7%, 12.0%, and 6.5%, respectively. Bortala River water D and 18O was enriched along the distance, and groundwater D and 18O in the north bank was generally more enriched than groundwater in the south bank as a whole. Under the control of geological conditions such as geological structure and hydrogeological conditions, the transformation of river water and groundwater was concentrated in the middle reaches of the Bortala River, which was generally manifested in both unconfined groundwater and spring overflow in the sides of the recharge river water, and the recharge proportion ranged from 1.0% to 70.9%.

Apelin is associated with clinicopathological parameters and prognosis in breast cancer patients.

PURPOSE: Apelin has been shown to be a novel angiogenic factor in various cancers. However, there is limited information regarding the role of apelin in breast cancer. The aim of the present study is to examine associations between apelin, clinicopathological variables, and clinical outcome in breast cancer patients. METHODS: In this study, we began by investigating the apelin expression in breast cancer with long-term follow-up using immunohistochemistry. We then analyzed the relationship between apelin expression and microvessel density (MVD), lymphatic vessel density (LVD), lymph node status as well as other established clinicopathological parameters. The relationship between apelin expression and prognosis was also studied. In addition, we compared the apelin and its ligant APJ expression between 30 breast cancer samples and normal breast tissues adjacent to the breast tumors using western blot (WB) and RT-PCR. RESULTS: Apelin protein expression was detected in the cytoplasm of the breast carcinoma cells at various intensities. Apelin expression was positive in 59.2% (84/142) of the breast cancer patients and apelin expression was significantly correlated with tumor size (p = 0.030), stage (p = 0.000), histological type (p = 0.009), MVD (p = 0.000), LVD (p = 0.000), and lymph node metastasis (p = 0.041). Survival curves determined by the Kaplan-Meier method and univariate analysis demonstrated that high expression of apelin was associated with both worse disease-free survival (p < 0.001) and overall survival (p < 0.001). Interestingly, a significant difference in apelin and APJ expression by WB as well as RT-PCR was observed between normal breast tissues adjacent to the breast tumors and breast cancer tissues. CONCLUSIONS: Our results showed apelin expression was associated with tumor size, stage, histological type, MVD, LVD, lymph node metastasis and poor prognosis. The presence of apelin may be a new prognostic factor and potential therapeutic target for breast cancer.

Starch as a reinforcement agent for poly(ionic liquid) hydrogels from deep eutectic solvent via frontal polymerization.

For the first time, conductive starch/poly(ionic liquid) hydrogels from a polymerizable deep eutectic solvent (DES) by frontal polymerization (FP) were reported. The solubility and dispersibility for starch granules in the polymerizable DES was investigated. The effects of starch content on FP behaviors, mechanical properties and electrical conductivity of composite hydrogels were studied. Results showed that starch could be partially dissolved and dispersed in the DES. Comparing with the pure poly(ionic liquid) hydrogel from DES (the tensile strength was 41 K Pa), the tensile strength of composite hydrogel could increased by 3.07 times and reached 126 K Pa. When the fixed strain was 80 %, its compressive strength could increase by 6 times and reaches 16.8 MPa. The main reason was that there was a strong interfacial interaction between starch and the polymer hydrogel network. The starch/poly(ionic liquid) composite hydrogels also had good electrical conductivity. Absorption of water could increase the conductivity of the composite hydrogel significantly.

Efficient Thermal Transport Highway Construction Within Epoxy Matrix via Hybrid Carbon Fibers and Alumina Particles.

Polymer composites with excellent thermal conductivity and superior mechanical strength are in high demand in the electrical engineering systems. However, achieving superior thermal conductivity and mechanical properties simultaneously at high loading of fillers will still be a challenging issue. In this work, a facile method was proposed to prepare the epoxy composite with carbon fibers (CFs) and alumina (Al2O3). This CF and Al2O3 hybrid structure can effectively reduce the interfacial thermal resistance between the matrix and the CFs. The thermal conductivity of epoxy composite with 6.4 wt % CFs and 74 wt % Al2O3 hybrid filler reaches 3.84 W/(m K), which is increasing by 2096% compared with that of pure epoxy. Meanwhile, the epoxy composite still retains outstanding thermal stability and mechanical performance at high filler loading. A cost-effective avenue to prepare highly thermally conductive and superior mechanical properties of polymer-based composites may enable some prospective application in advanced thermal management.

Graphene foam-embedded epoxy composites with significant thermal conductivity enhancement.

High thermal conductivity polymer composites at low filler loading are of considerable interest because of their wide range of applications. The construction of three-dimensional (3D) interconnected networks can offer a high-efficiency increase for the thermal conductivity of polymer composites. In this work, a facile and scalable method to prepare graphene foam (GF) via sacrificial commercial polyurethane (PU) sponge templates was developed. Highly thermally conductive composites were then prepared by impregnating epoxy resin into the GF structure. An ultrahigh thermal conductivity of 8.04 W m-1 K-1 was obtained at a low graphene loading of 6.8 wt%, which corresponds to a thermal conductivity enhancement of about 4473% compared to neat epoxy. This strategy provides a facile, low-cost and scalable method to construct a 3D filler network for high-performance composites with potential to be used in advanced electronic packaging.

Enhanced Thermal Conductivity of Epoxy Composites Filled with 2D Transition Metal Carbides (MXenes) with Ultralow Loading.

With the development of electronic devices such as integrated circuits toward the continual increase in power density and consumption, the efficient heat dissipation and low thermal expansion of materials become one of the most important issue. However, conventional polymers have the problem of poor thermal dissipation performance, which hinder application for electronic devices. In this work, the two-dimensional material, MXene (Ti3C2), is used as the reinforcement additive to optimize the thermal properties of polymers. We reported the preparation of multilayer Ti3C2 MXene by HF etching method and obtained few-layer Ti3C2 MXene by simple ultrasonication. Meanwhile, Ti3C2/epoxy composites were prepared by a solution blending method. The results show that the thermal properties of the composites are improved in comparison with the neat epoxy. Thermal conductivity value (0.587 W/mK) of epoxy composite with only 1.0 wt% Ti3C2 MXene fillers, is increased by 141.3% compared with that of neat epoxy. In addition, the composite presents an increased glass transition temperature, high thermal stability and lower coefficient of thermal expansion. This work is of great significance for the research of high-performance composite materials.

Graphene as a nanofiller for enhancing the tribological properties and thermal conductivity of base grease.

During mechanical processes, violent friction and wear between the friction contact surfaces not only causes wear to mechanical components, reducing the instrument life, but also causes friction heat, reducing the working efficiency of machines during operation. The addition of graphene-reinforced grease to the mechanical friction surface can effectively reduce the friction coefficient and improve the thermal conductivity. In this work, the tribological properties and thermal conductivity of base grease with graphene were investigated systematically. The tribological results showed that the grease with 2 wt% graphene had the best tribological properties among all these greases. The wear scar diameter and average friction coefficient of graphene grease with 2 wt% graphene reached 0.43 mm and 0.10 (the values for base grease are 0.50 mm and 0.118), respectively. In addition, the average friction coefficient and wear scar diameter increased proportionally with the increasing load and frequency. The thermal conductivity of the grease with 4 wt% graphene reached 0.28 W (m K)-1, an increase of 55.5% in comparison with the base grease. It is proposed that the addition of graphene into the base grease effectively enhanced the tribological properties and thermal conductivity.

Land-use/cover conversion affects soil organic-carbon stocks: A case study along the main channel of the Tarim River, China.

Soil organic carbon (SOC) constitutes a large pool within the global carbon cycle. Changes in land-use/cover strongly drive variation of SOC stocks. We analyzed the changes in four types of land use/cover and their influence on SOC content, density, and regional stocks along the main channel of the Tarim River in China for 2000-2010 obtained from remotely sensed images and field surveys. The areas and structures of the land uses/covers changed greatly during this period. Specifically, the areas of cultivated, industrial and residential, and shrub land increased, particularly cultivated and shrub land. The areas of forestland, grassland, water bodies, and unused land decreased. SOC stocks in forestland, grassland and unused land decreased between 2000 and 2010. The total SOC stock for the forestland shrub land grassland and unused land was lower in 2010 than 2000. Land-use/cover conversion thus affected SOC stocks. Specifically, conversions from forestland to shrub land, forestland to grassland, forestland to unused land, grassland to shrub land, grassland to unused land, and shrub land to unused land decreased the SOC stocks. This study provides a scientific basis for eco-environmental protection in arid areas.

A Distributed and Context-Aware Task Assignment Mechanism for Collaborative Mobile Edge Computing.

Mobile edge computing (MEC) is an emerging technology that leverages computing, storage, and network resources deployed at the proximity of users to offload their delay-sensitive tasks. Various existing facilities including mobile devices with idle resources, vehicles, and MEC servers deployed at base stations or road side units, could act as edges in the network. Since task offloading incurs extra transmission energy consumption and transmission latency, two key questions to be addressed in such an environment are (i) should the workload be offloaded to the edge or computed in terminals? (ii) Which edge, among the available ones, should the task be offloaded to? In this paper, we formulate the task assignment problem as a one-to-many matching game which is a powerful tool for studying the formation of a mutual beneficial relationship between two sets of agents. The main goal of our task assignment mechanism design is to reduce overall energy consumption, while satisfying task owners' heterogeneous delay requirements and supporting good scalability. An intensive simulation is conducted to evaluate the efficiency of our proposed mechanism.

Boron nitride nanosheet nanofluids for enhanced thermal conductivity.

It is difficult for traditional cooling liquids to meet equipment requirements due to the high power and high integration they demand. Nanofluids are nanoparticle dispersions with high thermal conductivities, thus they have been proposed for heat transfer applications. Boron nitride nanosheets (BNNSs) possess high thermal conductivities and excellent insulation properties. Here, we fabricated BNNS nanofluids and investigated their effects on thermal conductivity enhancements. We find that BNNSs can effectively enhance the thermal conductivity of water. The thermal conductivity of the BNNS nanofluids reached 2.39 W mK-1 at 24 vol% loading. The surface temperature changes of the nanofluids and water were observed during the heating process using an infrared camera. The results show that the nanofluids transfer heat much faster than water, indicating that the fabricated BNNS nanofluids have excellent thermal transfer properties.

Enhanced Thermal Conductivity of Polyimide Composites with Boron Nitride Nanosheets.

A strategy was reported to prepare boron nitride nanosheets (BNNSs) by a molten hydroxide assisted liquid exfoliation from hexagonal boron nitride (h-BN) powder. BNNSs with an average thickness of 3 nm were obtained by a facile, low-cost, and scalable exfoliation method. Highly thermally conductive polyimide (PI) composite films with BNNSs filler were prepared by solution-casting process. The in-plane thermal conductivity of PI composite films with 7 wt% BNNSs is up to 2.95 W/mK, which increased by 1,080% compared to the neat PI. In contrast, the out-of plane thermal conductivity of the composites is 0.44 W/mK, with an increase by only 76%. The high anisotropy of thermal conductivity was verified to be due to the high alignment of the BNNSs. The PI/BNNSs composite films are attractive for the thermal management applications in the field of next-generation electronic devices.

Anisotropic thermal conductive properties of cigarette filter-templated graphene/epoxy composites.

Herein, a cigarette filter-templated graphene/epoxy composite was prepared with enhanced thermal conductive properties. The through-plane thermal conductivity of the epoxy composite was up to 1.2 W mK-1, which was 4 times that of it in the in-plane (0.298 W mK-1) after only 5 filtration cycles. The thermal conductive anisotropy and improvement in the through-plane thermal conductivity of the epoxy composite were attributed to the particular structure of cigarette filter-templated graphene in the epoxy matrix. The unique structure formed effective conductive pathways in the composite to improve the thermal transportation properties. The excellent thermal transportation properties allow the epoxy composite to be used as an efficient heat dissipation material for thermal management applications.

Enhanced thermal conductivity of epoxy composites filled with tetrapod-shaped ZnO.

Epoxy composites with ZnO powders characterized by different structures as inclusion are prepared and their thermal properties are studied. The experimental results demonstrate that the epoxy resins filled by tetrapod-shaped ZnO (T-ZnO) whiskers have the superior thermal transport property in comparison to ZnO micron particles (ZnO MPs). The thermal conductivity of ZnO/epoxy and T-ZnO/epoxy composites in different mass fraction (10, 20, 30, 40, 50 wt%) are respectively investigated and the suitable models are compared to explain the enhancement effect of thermal conductivity. The thermal conductivity of T-ZnO/epoxy composites with 50 wt% filler reaches 4.38 W m-1 K-1, approximately 1816% enhancement as compared to neat epoxy. In contrast, the same mass fraction of ZnO MPs are incorporated into epoxy matrix showed less improvement on thermal conduction properties. This is because T-ZnO whiskers act as a thermal conductance bridge in the epoxy matrix. In addition, the other thermal properties of T-ZnO/epoxy composites are also improved. Furthermore, the T-ZnO/epoxy composite also presents a much reduced coefficient of thermal expansion (∼28.1 ppm K-1) and increased glass transition temperature (215.7 °C). This strategy meets the requirement for the rapid development of advanced electronic packaging.

Experimental study on water transport observations of desert riparian forests in the lower reaches of the Tarim River in China.

Studying the water use processes of desert riparian vegetation in arid regions and analyzing the response and adaptation strategies of plants to drought stress are of great significance for developing ecological restoration measures. Based on field monitoring and test analyses of physiological ecological indicators of dominant species (Populus euphratica and Tamarix chinensis) in the desert riparian forest in the lower reaches of the Tarim River, the water relations of P. euphratica and T. chinensis under drought stress are discussed and some water use strategies put forward. The results show that (1) concerning plant water uptake, desert riparian forests depend mainly on groundwater to survive under long-term water stress. (2) Concerning plant water distribution, the survival of P. euphratica and nearby shallow root plants is mainly due to the hydraulic lift and water redistribution of P. euphratica under drought stress. (3) Concerning plant water transport, P. euphratica sustains the survival of competitive and advantageous branches by improving their ability to acquire water while restraining the growth of inferior branches. (4) Concerning plant transpiration, the sap flow curves of daily variations of P. euphratica and T. chinensis were wide-peak sin and narrower-peak respectively. T. chinensis has better environmental adaptability.

The effects of groundwater depth on water uptake of Populus euphratica and Tamarix ramosissima in the hyperarid region of Northwestern China.

Knowledge of the water sources used by desert trees and shrubs is critical for understanding how they function and respond to groundwater decline and predicting the influence of water table changes on riparian plants. In this paper, we test whether increased depth to groundwater changed the water uptake pattern of desert riparian species and whether competition for water resources between trees and shrubs became more intense with a groundwater depth gradient. The water sources used by plants were calculated using the IsoSource model, and the results suggested differences in water uptake patterns with varying groundwater depths. At the river bank (groundwater depth = 1.8 m), Populus euphratica and Tamarix ramosissima both used a mixture of river water, groundwater, and deeper soil water (>75 cm). When groundwater depth was 3.8 m, trees and shrubs both depended predominantly on soil water stored at 150-375 cm depth. When the groundwater depth was 7.2 m, plant species switched to predominantly use both groundwater and deeper soil water (>375 cm). However, differences in water acquisition patterns between species were not found. The proportional similarity index (PSI) of proportional contribution to water uptake of different water resources between P. euphratica and T. ramosissima was calculated, and results showed that there was intense water resource competition between P. euphratica and T. ramosissima when grown at shallow groundwater depth (not more than 3.8 m), and the competition weakened when the groundwater depth increased to 7.2 m.