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Glass transition temperature (Tg) is important for the application of shape memory polymers (SMPs), and here shape memory polyimide (SMPI) with high Tg of 363 °C is reported. High shape recovery speed can improve reliability performance of SMP, and the introduction of modified boron nitride (M-BN) nanoparticles into SMPI matrix can enhance the recovery speed obviously. The faster recovery speed is mainly caused by the increase in thermal diffusivity, which enhances from 0.147 mm2 s−1 for primitive SMPI to 0.190 mm2 s−1 for the composite with 10% M-BN (SMPI/10% M-BN). Anti-wear capability is important for service life and performance reliability of materials, and wear rate decreases from 7.5 × 10−9 g N−1 r−1 for primitive SMPI to 0.83 × 10−9 g N−1 r−1 for SMPI/10% M-BN. The enhanced anti-wear capability is ascribed to high hardness, self-lubricating property and thermal conductivity of BN. Wear mechanism is studied, and it evolves from adhesive and fatigue wear for primitive SMPI to slight adhesive wear for SMPI/10% M-BN.

Incremental distribution network (IDN) is unique in China. It is a newly sprouted transition product in electric power system reform period. As IDN is huge in number and lacks in regulation, the pricing is a difficult problem needed to be solved. Chinese government has issued a regulation to set IDN price, however, which is widely considered unreasonable. This paper proposes a new IDN pricing mechanism based on allowed revenue method, and LASSO regression is applied to determine synthetic user allocation factor (SUAF), which is used to allocate the allowed revenue fairly and reasonably between different types of users. The study concludes that: IDN pricing mechanism proposed in this paper is consistent with pricing principle, and the pricing result is objective and reasonable which can be popularized and applied to all IDNs in China.

Purpose To improve power system peak dispatching ability, connecting energy-storage device such as electric vehicle (EV) and regenerative electric heater (REH) to power grid is a good choice. Design/methodology/approach This paper establishes a multi-energy combined peak dispatching system MCPDS which includes EV, REH and wind power. The matter-element extension model based on improved variable weight theory is applied to evaluate MCPDS synthetic benefit. Findings The research shows that the MCPDS established in this paper performs excellently in security benefit, economic benefit, social benefit and environmental benefit. Originality/value With the assistance of energy storage devices such as EV and REH, the electrical system peak dispatching ability and power system operation efficiency has improved. More devices with energy-storage ability should be introduced into electrical power system to improve its synthetic benefit.

Electric power system peak dispatching plays a very important role in leveling the load curve, strengthening grid stability, and conserving energy. The inadequate capability of peak dispatching is a leading factor in incomplete wind power integration and poor load characteristics. Adding energy storage on the demand side can improve system peak dispatching ability, promote wind power, and optimize the load curve. This paper first analyzes the mechanisms of regenerative electric heaters (REHs) and electric vehicles (EV) on peak dispatching, based on which a multi-energy hybrid peak dispatching system is designed. Taking into account economic, environmental, and societal benefits and equivalent load curve fluctuation level, this study establishes a multi-energy hybrid peak dispatching optimization model that considers general as well as REH and EV load-control constraints. In view of the shortcomings of particle swarm optimization (PSO), a two-phase force (TPF) rule is introduced in searching process to improve PSO searching performance. The research result reveals that: TPF rule can optimize PSO searching performance and help obtain the best peak-dispatching scheme. In addition, the multi-energy hybrid peak dispatching system designed here offers advantages in leveling the load curve, optimizing power output, conserving energy and reducing emissions, and yield economic benefits.

Hazardous wastes in power grids include waste transformer oil and waste lead-acid batteries, etc. Due to the problems of extremely large number of points, wide distribution, and small number of units, coupled with differences in hazardous waste recycling technologies, policies, and markets in various regions, so Possible business models need to be listed and evaluated. This paper establishes an evaluation index system for the business model of hazardous waste recycling, and uses the TOPSIS method to evaluate five feasible business models. The evaluation results will help relevant departments of power grid companies at all levels to formulate recycling strategies according to the characteristics of hazardous waste recycling, so as to facilitate the recycling and reuse of hazardous wastes.

The Transition of clean and renewable energy to fossil energy as well as the clean use of fossil energy is the main trend of energy system, which promotes energy system transform to a clean efficient and intelligent status. Accordingly, related policies transform to efficiency and benefit, technical innovation, based on energy security. This paper bases on scientific analysis of the evolution trend of energy transformation and energy policy system, designs energy transformation policy system in the aspect of implementation aims and objects, in order to provide references for energy system transformation.

China has encountered a huge challenge in the process of wind development due to serious wind curtailment and lower generation efficiency. Inferior wind turbines micrositing is the main reason leading to such problems. In order to better assess the wind turbines micrositing of wind farms (WF) in China, two-subprocess data envelopment analysis (DEA) model is proposed. The improved DEA model divides the complicated system of wind turbines micrositing into two subprocesses: wind turbines arrangement subprocess and power production optimization subprocess, and then the efficiencies of the two subprocesses are assessed respectively. The superiority of the proposed model is proved by a case study. Then, the efficiency scores obtained by two-subprocess DEA are taken as the dependent variables, and Tobit regression model is employed to explore the relationship between the efficiency scores and the environment variables. The study result reveals that: two-subprocess DEA can find out in which subprocess the low efficiency exits; Tobit model can find if the environmental factors are significant or not, and further justify in which subprocess the environmental factors play significant roles. In addition, the environmental factors of the integrity and rationality of data exerts positive and significant influence on micrositing efficiency, but terrain roughness is proven to adversely affect the micrositing effect of wind farms.

Purpose The aim of this paper is to review the current situation and existing problem, establish investment benefits evaluation indicator system and introduce synthetic approach degree containing Hamming approach degree, Euclid approach degree and gray correlation degree to improve the shortage of Euclidean distance in traditional TOPSIS method, and the evaluation result is strengthened by multiplication rule. This paper aims to solve the distribution network investment decision-making problem and construct a comprehensive distribution network investment benefit indicator system, which is more suitable for China distribution network characteristics. Design/methodology/approach This study develops improved TOPSIS methods for decision maker in the power distribution network market and uses an example to prove its effectiveness and superiority in practice which can realize the combination of theory and practice. Findings The research shows that the investment evaluation indicator system built in present paper covers more investment benefit influencing factors (such as qualified rate of trunk cross-section, pass rate of N-1 lines), and the evaluation result obtained by improved TOPSIS method is more efficient and persuasive. Originality/value The study can help investors evaluate distribution network project more efficient, and make contribution to the choice of distribution cases with similar investment benefits.

Elimination of high-emitting industrial capacity can be an effective way to control and relieve air pollution but it will also influence demand. Accurate forecasting of electricity demand requires consideration of the impact of capacity elimination policies. This paper applies a modified firefly algorithm improved by Gaussian disturbance to optimize the parameters of Support Vector Machine (SVM) in order to quantify the impact of capacity elimination policies. We consider three policy scenarios and three growth scenarios in our analysis. The results demonstrate that modified firefly algorithm (MFA) can improve the forecasting performance of SVM and electricity demand forecasting considering the influence of capacity elimination policies, and provide good reference for policy analysis and electricity demand analysis.

Under the effects of environmental pollution, macro-economical conditions, markets downturn, and squeeze of clean energy, the operation condition of China's whole coal industry attracts more attentions in recent years. This study aims to investigate the comprehensive competitiveness of coal industry in Chinese policy and economy environment. Then, this paper adopts diamond model to analyze internal and external factors that have significant influences on the competitiveness of China's coal industry, namely resource condition, demand condition, industry structure and enterprise strategy, related and support industries, the government, technology and chance. The research indicates that Chinese coal industry suffers from excessive capacity, low coal price and substitute of clean energy, etc. The current performance of Chinese coal industry is not optimistic. Fortunately, Chinese government unceasingly issues policies to support and regulate coal industry, and coal enterprises actively participate in industrial structure adjustments to deal with pressure of downturn. Furthermore, some national strategies, such as Ultra High Voltage transmission and ‘One Belt And One Road’, will greatly promote the recovery of domestic coal industry. In order to survive the downturn and sustain its fundamental position, coal industry should attach importance to these key factors in diamond model for each of them has crucial influences on the comprehensive competitiveness of Chinese coal industry.

In 2013, “haze-fog” became an annual buzzword in China; this “haze-fog” is primarily attributed to coal combustion. If coal continues to be used as it has been previously, China will suffer as a result of air pollution. Different from coal, electricity is a highly efficient energy source with no pollution emissions. Electric power substitution (EPS) for coal can reduce air pollution and transmit electricity to a load intensive area by an ultra-high voltage transmission project that can promote renewable energy accommodations in remote areas. However, EPS was proposed in 2013 and is still in the initial stage. The present paper studies the relationship between coal and haze-fog, proposes an EPS action mechanism, and summarizes the EPS market and policies. A SWOT model has proved to be an efficient tool to analyze the internal and external competitiveness of a system. Therefore, to fully study the current development status of electric power substitution in China, this paper adopts a SWOT model to analyze the strengths, weaknesses, opportunities and threats of EPS. The conclusion is drawn that EPS is a good substitution for coal, but increased interest and use of EPS in China still needs support, including energy price marketization, electricity price subsidy, UHV optimization, clean coal technology innovation, and so on. This research can promote optimization in the energy structure and provides policy makers with good references and a clear direction in EPS development.

Since 2012 the coal industry in China has deeply fallen into depression. When entering into 2015, the tragedy continued. What the future of China's coal is has confused the scholars and managers. In order to evaluate the current competitiveness of coal industry in China, the diamond model is employed in present study to analyze the influence of six components on the competitiveness, namely factor condition, demand condition, related and support department, firm strategy, structure and rivalry, government, chance. The result of diamond model shows that the coal industry suffers from excessive capacity, low industry concentration ratio, low price and low investment, etc. The current competitiveness of coal industry in China is not satisfactory. Fortunately, China government has issued lists of policies to recover the industry. Besides, some strategic plans provide great chances for the recovery of coal industry. At the end of this paper, a gear model is applied to design a dynamic competitiveness improvement mechanism of coal industry in China. The model shows that the power comes from the coal industry itself is the main active force to impel the improvement of coal industry competitiveness, and the government, chance, related and support department play accessory but indispensable roles.

Emerging evidence has demonstrated an important role of microRNAs (miRNAs) in the pathogenesis of cerebral infarction. In the present study, a down-regulation of microRNA-433 (miR-433) is identified in hypoxia-induced human umbilical vein vascular endothelial cells (HUVECs) as well as in rat neurons, and is found to be negatively regulated cell proliferation and migration. Moreover, the expression of miR-433 is inversely correlated with the expression of hypoxia-inducible factor 1 alpha (HIF-1α), which has been shown to play critical role in responding to hypoxia conditions. Overexpression or knockdown of miR-433 responsively alters both mRNA and protein levels of HIF-1α and its downstream genes, vascular endothelial growth factor, Glut-1, and Angpt2. In a luciferase reporter system, miR-433 down-regulates the luciferase activity of HIF-1α 3'-UTR, and these effects are abolished by a mutation in the putative miR-433-binding site. Further investigation confirms that knockdown of HIF-1α blocked the stimulatory effect of anti-miR-433, while overexpression of HIF-1α reversed the inhibitory effects of pre-miR-433 on proliferation and migration of HUVEC and neurons. Taken together, our findings indicate that miR-433 plays an important role in response to hypoxia, inhibiting HUVEC and neuron proliferation and migration by down-regulating HIF-1α.

High temperature electromagnetic shielding materials that can eliminate electromagnetic interference (EMI) and withstand high temperature have vast potential in cutting-edge applications like aircraft, and here electromagnetic shielding shape memory polyimide (EMSMPI) is reported for the first time. EMSMPI is synthesized by incorporating 5% short carbon fiber and 4% carbon black into shape memory polyimide matrix, its glass transition temperature of 308 °C is higher than other electromagnetic shielding polymers, and it can hang the kettle 43,000 times heavier than itself. The 0.35 mm thick EMSMPI film exhibits nice shielding effects with average EMI shielding effectiveness of 23.9 dB in X-band, and its shielding mechanism is discussed. Shape processability of EMSMPI endowed by shape memory effect is valuable for sophisticated devices as it can be processed into different shapes conveniently, and shielding effectiveness after thirty cycles is still higher than the recommended limit of 20 dB for commercial applications.

Recovery stress is important for smart shape memory materials (SMMs) and low recovery stress of shape memory polymers hinders their applications badly, while high temperature shape memory alloys (HTSMAs) are very difficult to be obtained. In order to obtain high temperature SMM with high recovery stress, convenient preparation methods, low cost and good workability, shape memory polyimide with high recovery stress (HRSMPI) at the level of HTSMA is prepared by reinforcing smart polyimide matrix with carbon fiber cloth (CFC) in common lab furnace. The HRSMPI possesses unique sandwich structure with good interfacial bonding between the matrix and filler. It exhibits high glass transition temperature of 300 °C, shape fixity of 90.6% and shape recovery of 92.2%. The recovery stress of HRSMPI is 116 MPa, close to those of some HTSMAs. The primitive actuator made of HRSMPI can overturn metal sheet 147 times heavier than itself, similar to the commercial TiNiHf HTSMA. Meanwhile, its density is 0.96 g cm−3, less than 1/6 of that of TiNiHf. The elastic strain energy is mainly stored in CFC and then released as recovery stress under constrained shape recovery, and HRSMPI has great potential in practical applications.

China has been the world’s leader in wind power capacity due to the promotion of favorable policies. Given the rare research on the efficiency of China’s wind farms, this study analyzes the productive efficiency of 42 large-scale wind farms in China using a two-stage analysis. In the first stage, efficiency scores of wind farms are determined with data envelopment analysis and the sensitivity analysis is conducted to verify the robustness of efficiency calculation results. In the second stage, the Tobit regression is employed to explore the relationship between the efficiency scores and the environment variables that are beyond the control of wind farms. According to the results, all wind farms studied operate at an acceptable level. However, 50% of them overinvest in the installed capacity and about 48% have the electricity-saving potential. The most important factors affecting the efficiency of wind farms are the installed capacity and the wind power density. In addition, the age of the wind farm and the wind curtailment rate have a negative effect on productive efficiency, whereas the ownership of the wind farm has no significant effect. Findings from this study may be helpful for stakeholders in the wind industry to select wind power projects, optimize operational strategies and make related policies.

Accurate short-term load forecasting plays a crucial role in electricity industry and market. In this study, a novel forecasting method based on Support Vector Machine (SVM) and Firefly Algorithm (FA) has been created to realize accurate and reliable load prediction. The performance of SVM highly depends on the selection of parameters, and Gaussian disturbance Firefly Algorithm (GDFA) proposed in this study can satisfy the necessary. Ensemble Empirical Mode Decomposition (EEMD) is employed to decompose the load data into sub-series with different frequency. This paper extracts daily maximum temperature, daily minimum temperature, wind speed, rainfall, day type, and the load one week before the forecasting day as input variables. Two cases are taken to verify the effective performance of GDFA compared with FA, as well as the superiority of EEMD-GDFA-SVM over other forecasting techniques in short-term load forecasting.

Self-healing can improve reliability and extend service lifetime of materials while shape memory polymers (SMPs) have potential in many smart applications, and here self-healing shape memory polyimide (SHSMPI) that can heal damages at high temperature is fabricated for the first time. SHSMPI is synthesized by incorporating fusible thermoplastic polystyrene (PS) at 8% weight content into shape memory polyimide (SMPI) matrix, and it exhibits excellent shape memory effect. SHSMPI can self-heal crack, pierced hole, and cut effectively at heal-temperature of 243 °C. Self-healing mechanism of SHSMPI is discussed, and SMPI matrix produces spatial proximity through shape memory effect while PS acts as healing agent to heal the damages. SHSMPI can produce stored energy of 0.105 J g−1 at the efficiency of 33.1% upon triggering. The designing of SHSMPI at macroscale makes it suitable for mass production, and the self-healing performance will greatly expand application areas of SMPI.

Hydroxyapatite (HAp) nanorods possess vast potential applications in various fields, and here HAp nanorods with high aspect ratio were synthesized via a convenient two-stage precipitation-hydrolysis process at 60°C under atmospheric pressure. The precursor of CaHPO4 at precipitation stage is well crystallized as nubby morphology with CTAB as surfactant, while CaHPO4 was dissolved and CTA+ stabilized the HAp nuclei during the hydrolysis stage. OH− ions were absorbed onto the active crystal surface, where Ca2+ and PO43+ reacted with OH− to make the nuclei grow into larger crystals, and highly crystalline HAp nanorods were obtained by Ostwald ripening. The loaded drug of IBU on the HAp crystals can be 100% released in 24 h. PVP modified HAp nanorods can increase the drug-loading capacity and release drug faster than pure HAp nanorods. The results indicate that HAp nanorods modified with suitable surfactants are of great use in drug delivery system.

One-dimensional hydroxyapatite (HAp, Ca10(PO4)6(OH)2) nanocrystals have been successfully synthesised via the simple precipitation-hydrolysis process on mild solution conditions. At the first precipitation step, the precursor samples of monetite phase CaHPO4 were prepared with three kinds of organic additives. The results of X-ray diffraction (XRD) patterns show that the structure and crystallinity of CaHPO4 prepared with the different organic additives are different, which indicates that the organic additives exert influence on the crystal growth of CaHPO4. During the second process, the HAp nanocrystals with high aspect ratio grew up under a high pH condition. The XRD patterns show that the preference of every nanocrystal growth is the (002) plane. Transmission electron microscopy micrographs indicate that the HAp nanocrystals were affected by the reaction temperature and the pH values of the solution. The organic additives influenced the aspect ratio of HAp nanocrystals, and Fourier transform infrared spectra show that the organic additives were completely dissolved in the aqueous system. This indicates that the organic additives affected the formation of nucleation and growth of HAp nanocrystals, and the influence gradually decreased with the extension of the hydrolysis time, until the organic additives were detached from the HAp crystals.

Shape-memory polymers (SMPs) are synthesized with adjustable glass transition temperature (Tg) ranging from 299 to 322 °C, higher than those reported previously. The polyimide containing thermal stable but flexible linkages within the backbone act as reversible phase, and high molecular weight (Mn) is necessary to form physical cross-links as fixed phase of thermoplastic shape-memory polyimide. The critical Mn is 21.3 kg/mol, and the relationship between Mn and Tg is explored. Thermoset polyimides show higher storage modulus and better shape-memory effects than thermoplastic counterparts due to covalent cross-linking, and the effective cross-link density with the influence on their physical properties is studied. The mechanism of high-temperature shape-memory effect of polyimide on the basis of chain flexibility, molecular weight, and cross-link density is proposed, which will benefit further research on high-temperature SMPs.

Despite the rapid development of shale gas in China, further development encounters strong resistances owing to the impact of the late start, relatively backward technology and other factors. First, this article studies the worldwide status of technological development of shale gas, reviews key technology of shale gas exploration and development mastered in China, and compares shale gas-related technical conditions between China and foreign. Then the SWOT analysis is applied to research and analyze the factors affecting the technological development of Chinese shale gas industry, and their influence mechanism is investigated thoroughly to identify the key factors that influence the technological development of shale gas. Finally, the result shows that Chinese technological level in shale gas industry is still relatively backward, despite having made some progresses. Government support policy, Sino-foreign cooperations and exchanges and healthy competition are significant and in great need.

Studies have shown that long noncoding ribonucleic acids (lncRNAs) play critical roles in multiple biologic processes. However, the Small Nucleolar RNA Host Gene 1 (SNHG1) function and underlying molecular mechanisms in ischemic stroke have not yet been reported. In the present study, we found that SNHG1 expression was remarkably increased both in isolated cerebral micro-vessels of a middle cerebral artery occlusion (MCAO) mice model, and in oxygen-glucose deprivation (OGD)-cultured mice brain micro-vascular endothelial cells (BMECs), meanwhile, the SNHG1 level was negatively correlated with miR-18a in MCAO mice. Mechanistically, SNHG1 inhibition presents larger brain infarct size and worsens neurological scores in MCAO mice. Consistent with the in vivo findings, SNHG1 inhibition also significantly increased caspase-3 activity and cell apoptosis in OGD-cultured BMECs. Furthermore, we found that SNHG1 functions as a competing endogenous RNA (ceRNA) for miR-18a, thereby regulating the de-repression of its endogenous target HIF-1α and promoting BMEC survival through HIF-1α/VEGF signaling. This study found a neuroprotective effect of SNHG1 mediated by HIF-1α/VEGF signaling through acting as a ceRNA for miR-18a. These findings reveal a novel function of SNHG1, which contributes to an extensive understanding of ischemic stroke and provides novel therapeutic options for this disease.

Flexible and semi-rigid heat-shrinkable tubes (HSTs) have been used in thousands of applications, and here rigid high temperature HSTs are reported for the first time. These rigid HSTs are prepared with shape memory polyimides possessing glass transition temperatures (Tgs) from 182 to 295 °C, and the relationships between Tg and their molecular structures are studied. The polyimide HSTs (PIHSTs) can fix expanded diameters and shrink back to original diameters very well, and the mechanisms of their heat-shrinkage performance are discussed. Their differences from commercially available HSTs in heat-shrinkage are also analyzed. They can withstand low temperature of −196 °C, much lower than those of other HSTs. The PIHSTs can also connect subjects of different sizes by heat-shrinkage and then fix them upon cooling like reducer couplings, and the possible mechanisms of their reducer coupling effect are analyzed. With their unique characteristics, PIHSTs will expand the application areas of HSTs enormously.

High temperature shape memory polymers (SMP) have potentials in aerospace and electronic industries, while wear resistance can enhance reliability and service life of products. Here high temperature SMP with high resistance are prepared for the first time by introducing 3-aminopropyltriethoxysilane modified SiO2 nanoparticles (A-SiO2) into new shape memory polyimide (SMPI) matrix. The composite with 10 % A-SiO2 exhibits high glass transition temperature (Tg) of 256 °C, complete shape fixity and shape recovery of 100 %, and low wear rate of 1.67×10-9 g. N-1. r-1. In comparison, neat SMPI exhibits poor wear resistance with serious damages after the same dry sliding, and its wear rate is 5.83×10-9 g. N-1. r-1. The wear mechanism is studied and the wear evolves from adhesive and fatigue wear of neat SMPI to slight adhesive wear of the composite with 10 % A-SiO2.

High cycle-life is important for shape memory materials exposed to numerous cycles, and here we report shape memory polyimide that maintained both high shape fixity (Rf) and shape recovery (Rr) during the more than 1000 bending cycles tested. Its critical stress is 2.78 MPa at 250 °C, and the shape recovery process can produce stored energy of 0.218 J g−1 at the efficiency of 31.3%. Its high Rf is determined by the large difference in storage modulus at rubbery and glassy states, while the high Rr mainly originates from its permanent phase composed of strong π-π interactions and massive chain entanglements. Both difference in storage modulus and overall permanent phase were preserved during the bending deformation cycles, and thus high Rf and Rr were observed in every cycle and the high cycle-life will expand application areas of SMPs enormously.

Optically transparent shape memory polymers (SMPs) have potential in advanced optoelectronic and other common shape memory applications, and here optically transparent shape memory polyimide is reported for the first time. The polyimide possesses a glass transition temperature (Tg) of 171 °C, higher than the Tg of other transparent SMPs reported, and the influence of molecular structure on Tg is discussed. The 120 μm thick polyimide film exhibits transmittance higher than 81% in 450–800 nm, and the possible mechanism of its high transparency is analyzed, which will benefit further research on other transparent high temperature SMPs. The transparent polyimide showed excellent thermomechanical properties and shape memory performances, and retained high optical transparency after many shape memory cycles.

Doppel (Dpl) is a prion (PrP)-like protein due to the structural and biochemical similarities; however, the natural functions of Dpl and PrP remain unclear. In this study, a 531-bp human PRND gene sequence encoding Dpl protein was amplified from human peripheral blood leucocytes. Full-length and various truncated human Dpl and PrP proteins were expressed and purified from Escherichia coli. Supplement of the full-length Dpl onto human neuroblastoma cell SH-SY5Y induced remarkable cytotoxicity, and the region responsible for its cytotoxicity was mapped at the middle segment of Dpl [amino acids (aa) 81-122]. Interestingly, Dpl-induced cytotoxicity was antagonized by the presence of fulllength wild-type PrP. Analysis on fragments of PrP mutants showed that the N-terminal fragment (aa 23- 90) of PrP was responsible for the protective activity. A truncated PrP (PrPdelta32-121) with similar secondary structure as Dpl induced Dpl-like cytotoxicity on SHSY5Y cells. Furthermore, binding of copper ion could enhance the antagonizing effect of PrP on Dpl-induced cytotoxicity. Apoptosis assays revealed that cytotoxicity induced by Dpl occurred through an apoptotic mechanism. These results suggested that the function of Dpl is antagonistic to PrP rather than synergistic.