A new multivariate grey prediction model for forecasting China's regional energy consumption.

Predicting energy consumption is an essential part of energy planning and management. The reliable prediction of regional energy consumption is crucial for the authority in China to formulate policies by with respect to the dual control of its energy consumption and energy intensity. Given that energy consumption is affected by a number of factors, this study proposes a non-homogeneous, discrete, multivariate grey prediction model based on adjacent accumulation to predict the regional energy consumption in China. Interestingly regional GDP was selected by grey relational analysis as the independent variable in the proposed model. The results show that it can outperform the other multivariate grey models considered in terms of predicting regional energy consumption in China. Moreover, we found that economic development and energy consumption of each region in China remain closely related. In the post-COVID-19 period, regional economic development will continue to grow and increase energy consumption.

Snake Tracks in Polymer Land: Wavy Polymer Structures via Selective Solvent Vapor Annealing.

Wavy patterns are interesting geometric patterns and commonly seen in nature, such as serpentine streams or snake tracks in the sand. Although many efforts have been devoted to fabricating artificial wavy structures, it remains a great challenge to obtain wavy structures with controllable curvatures and desired functional properties. Here, we present an unprecedented approach to generate wavy polymer structures by annealing electrospun core-shell fibers on polymer films. Polystyrene (PS)/poly(methyl methacrylate) (PMMA) core-shell fibers, produced via the viscosity-induced phase separation in the electrospinning process, are annealed on PMMA films using vapors of acetic acid, a selective solvent for PMMA but not for PS. After the swollen PMMA chains of the PMMA shells are shed, the revealed PS cores start to buckle, driven by the elastic force from the strain release, forming the wavy structures. The degrees of the buckling, measured by the curvatures and the amplitudes of the wavy structures, are controlled by the annealing times. Furthermore, fluorescent properties are selectively introduced to the wavy structures using pyrene solutions or pyrene-containing vapors, demonstrating the potential application as fluorescent wavy materials.

Solvent-Induced Shape Recovery of Anisotropic Polymer Particles Prepared by a Modified Thermal Stretching Method.

Anisotropic polymer particles have attracted great attention because of their unique properties and potential applications in various areas, such as microelectronics, drug delivery, and medical imaging. The fabrication and morphology control, especially the shape recovery, of anisotropic polymer particles, however, remains a challenging task. In this work, we develop a novel strategy to fabricate anisotropic polymer particles by thermally stretching poly(vinyl alcohol) (PVA) films embedding polystyrene (PS) microspheres using a weight. Depending on the preannealing condition, anisotropic PS particles with two different shapes, sharp-headed and blunt-headed PS particles, can be obtained. The PVA films can be selectively removed by isopropanol/water, releasing the anisotropic PS particles. By adding tetrahydrofuran (THF), a good solvent for PS, into the PS particle-containing solutions, the anisotropic particles gradually transform back to spheres to reduce the total interfacial energies. The shape recovery rates of the polymer particles can be controlled by the amount of the added THF. This work not only provides a simple and feasible route to fabricate anisotropic polymer particles but also contributes to a deeper understanding in the solvent-induced shape recovery process from anisotropic polymer particles to polymer spheres.

Fabrication and Thermal Insulation Properties of Bamboo-Shaped Polymer Fibers by Selective Solvent Vapor Annealing.

Fibrillar materials have gained much attention recently because of their unique properties and potential applications. Although many methods have been developed to fabricate materials, it remains challenging to prepare fibrillar materials containing multicomponent materials or even with complex structures. Here, a facile strategy is developed to fabricate bamboo-shaped fibers by treating electrospun polymer core-shell fibers with solvent vapor annealing. Electrospun polystyrene (PS)/poly(methyl methacrylate) (PMMA) core-shell fibers are first prepared by electrospinning PS/PMMA blend solutions via a phase separation process. When the PS/PMMA core-shell fibers are annealed with the vapor of cyclohexane, which swells and delocalizes the PS domains selectively, the fibers transform into bamboo-shaped structures. The bamboo-shaped structures can be further examined by swelling and delocalizing the PMMA domains selectively, revealing the undulated PS structures. The thermal insulation properties of the fibers with bamboo-shaped structures are observed to be enhanced compared with the original polymer core-shell fibers.

Thermal-Annealing-Induced Self-Stretching: Fabrication of Anisotropic Polymer Particles on Polymer Films.

Designing anisotropic particles of various shapes draws great attention to scientists nowadays. We develop a facile and simple method to fabricate anisotropic polymer particles from spherical polymer particles. Poly(vinyl alcohol) (PVA) films spin-coated with polystyrene (PS) microspheres are confined on both sides using binder clips and are heated above the glass-transition temperatures of the polymers. During the thermal annealing process, the PS particles sink into the PVA films and transform to anisotropic particles. Depending on the distances to the bound regions, oblate spheroid PS particles or prolate spheroid particles with different aspect ratios can be obtained. The transformation of the particles is mainly driven by the stretching forces and the squeezing forces. The main advantage of this method is that anisotropic particles with different shapes can be fabricated simultaneously on a single film. We expect that this novel method can be helpful to various fields including colloids science, suspension rheology, and drug delivery.

Plateau-Rayleigh Instability Morphology Evolution (PRIME): From Electrospun Core-Shell Polymer Fibers to Polymer Microbowls.

Electrospun core-shell fibers have great potentials in many areas, such as tissue engineering, drug delivery, and organic solar cells. Although many core-shell fibers have been prepared and studied, the morphology transformation of core-shell fibers have been rarely studied. In this work, the morphology evolution of electrospun core-shell polymer fibers driven by the Plateau-Rayleigh instability is investigated. Polystyrene/poly(methyl methacrylate) (PS/PMMA) core-shell fibers are first prepared by using blend solutions and a single axial electrospinning setup. After PS/PMMA core-shell fibers are annealed on a PS film, the fibers undulate and sink into the polymer film, forming core-shell hemispheres. The evolution process, which can be observed in situ by optical microscopy, is mainly driven by achieving lower surface and interfacial energies. The morphologies of the transformed structures can be confirmed by a selective removal technique, and polymer microbowls can be obtained.

Fabrication of Electrospun Polymer Fibers with Nonspherical Cross-Sections Using a Nanopressing Technique.

The fabrication of electrospun polymer fibers is demonstrated with anisotropic cross-sections by applying a simple pressing method. Electrospun polystyrene or poly(methyl methacrylate) fibers are pressed by flat or patterned substrates while the samples are annealed at elevated temperatures. The shapes and morphologies of the pressed polymer fibers are controlled by the experimental conditions such as the pressing force, the pressing temperature, the pressing time, and the surface pattern of the substrate. At the same pressing force, the shape changes of the polymer fibers can be controlled by the pressing time. For shorter pressing times, the deformation process is dominated by the effect of pressing and fibers with barrel-shaped cross-sections can be generated. For longer pressing times, the effect of wetting becomes more important and fibers with dumbbell-shaped cross-sections can be obtained. Hierarchical polymer fibers with nanorods are fabricated by pressing the fibers with porous anodic aluminum oxide templates.

A correlational study of suicidal ideation with psychological distress, depression, and demoralization in patients with cancer.

PURPOSE: This study aims to study the effects of depression and demoralization on suicidal ideation and to determine the feasibility of the Distress Thermometer as a screening tool for patients with cancer who experience depression and demoralization, and thus to establish a model screening process for suicide prevention. METHODS: Purposive sampling was used to invite inpatients and outpatients with lung cancer, leukemia, and lymphoma. Two hundred participants completed the questionnaire, which included the Distress Thermometer (DT), Patient Health Questionnaire-9 (PHQ-9), Demoralization Scale-Mandarin Version (DS-MV), and Beck Scale for Suicide Ideation. All data obtained were analyzed using SPSS 18.0 and SAS 9.3. RESULTS: Tobit regression analysis showed that demoralization influenced suicidal ideation more than depression did (t = 2.84, p < 0.01). When PHQ-9 ≥ 10 and DS-MV ≥42 were used as criteria for the DT, receiver operating characteristic analysis revealed that the AUC values were 0.77-0.79, with optimal cutoff points for both of DT ≥5; sensitivity 76.9 and 80.6 %, respectively; and specificity of 73.9 and 72.2 %, respectively. CONCLUSIONS: Demoralization had more influence on suicidal ideation than depression did. Therefore, attention should be paid to highly demoralized patients with cancer or high demoralization comorbid with depression for the purposes of suicide evaluation and prevention. The DT scale (with a cutoff of ≥5 points) has discriminative ability as a screening tool for demoralization or depression and can also be used in clinical settings for the preliminary screening of patients with cancer and high suicide risk.

The Effect of Solvent Vapor Annealing on Drug-Loaded Electrospun Polymer Fibers.

Electrospinning has emerged as a powerful strategy to develop controlled release drug delivery systems but the effects of post-fabrication solvent vapor annealing on drug-loaded electrospun fibers have not been explored to date. In this work, electrospun poly(ԑ-caprolactone) (PCL) fibers loaded with the hydrophobic small-molecule spironolactone (SPL) were explored. Immediately after fabrication, the fibers are smooth and cylindrical. However, during storage the PCL crystallinity in the fibers is observed to increase, demonstrating a lack of stability. When freshly-prepared fibers are annealed with acetone vapor, the amorphous PCL chains recrystallize, resulting in the fiber surfaces becoming wrinkled and yielding shish-kebab like structures. This effect does not arise after the fibers have been aged. SPL is found to be amorphously dispersed in the PCL matrix both immediately after electrospinning and after annealing. In vitro dissolution studies revealed that while the fresh fibers show a rapid burst of SPL release, after annealing more extended release profiles are observed. Both the rate and extent of release can be varied through changing the annealing time. Further, the annealed formulations are shown to be stable upon storage.

Sequential Selective Solvent On-Film Annealing: Fabrication of Monolayers of Ordered Anisotropic Polymer Particles.

Although various strategies have been developed to prepare anisotropic polymeric particles, it remains challenging to fabricate monolayers of anisotropic polymeric particles, which can extend the applications of anisotropic particles. Here, we develop a novel and facile approach to fabricate monolayers of anisotropic polymeric particles. Monolayers of polystyrene (PS) microspheres with a mean diameter of 10 µm are deposited on glass substrates coated with poly(methyl methacrylate) films, followed by sequential selective solvent on-film annealing processes. Monolayers of anisotropic polymeric particles, such as the snowman-like PS particles, are successfully fabricated. Such unique structures possess the long-range ordering of monolayers (the structure factor) and the anisotropic geometry of individual particles (the form factor). The nanomechanical properties of the PS particles are also characterized using atomic force microscopy force volume measurements, showing a decrease in the Young's moduli of the PS particles owing to the looser packing of the polymer chains. This work provides the most facile and versatile strategy by far to fabricate monolayers of ordered anisotropic polymeric particles, which are inaccessible by other traditional means.

The effect of collection substrate on electrospun ciprofloxacin-loaded poly(vinylpyrrolidone) and ethyl cellulose nanofibers as potential wound dressing materials.

In this work, nanofibers based on hydrophilic poly(vinylpyrrolidone) (PVP) and hydrophobic ethyl cellulose (EC) were generated via electrospinning. A model antibiotic, ciprofloxacin (CIF), was also incorporated into the fibers. Fibers were collected on both a foil substrate and a commercial gauze, the latter in the interests of developing a smart fabric. Electron microscopy images revealed that the fibers collected on both foil and fabric were homogeneous and cylindrical. Infrared spectroscopy, X-ray diffraction and differential scanning calorimetry demonstrated that CIF was successfully loaded into the fibers and present in the amorphous physical form. In vitro drug release tests were conducted to simulate drug release from the formulations into a wound site, and as expected the hydrophilic fibers showed much faster release than their hydrophobic analogues. CIF was released through a combined mechanism of polymer erosion and drug diffusion, and the EC nanofibers displayed close to zero-order release over three days. Fibroblast cells are able to grow and proliferate on the fibers. Finally, inhibition zone assays revealed that the growth of both Gram positive and Gram negative bacteria could be effectively inhibited as a result of the presence of CIF in the fibers. There were no marked differences between the fibers collected on foil and on gauze, and electrospinning can be performed directly onto a gauze substrate to prepare a smart fabric.

On-Film Annealing: A Simple Method to Fabricate Heterogeneous Polymer Surfaces, Porous Films, and Hemispheres.

Polymer microspheres have been widely investigated because of their applications in areas such as drug delivery, latex diagnostics, and affinity bioseparators. The effect of annealing on polymer microspheres, however, has been rarely studied. In this work, we demonstrate the morphology transformation of polystyrene (PS) microspheres annealed thermally on poly(methyl methacrylate) (PMMA) films. During the annealing process, the PS microspheres gradually sink into the PMMA films and transform into PS hemispheres, driven by the reduction of the surface and interfacial energies. The effect of the film thicknesses on the morphology transformation is also studied. In addition, porous PMMA films or PS hemispheres can be obtained by removing the PS or the PMMA domains of the polymer composites using cyclohexane or acetic acid, respectively.