Advances in polymeric nano-delivery systems targeting hair follicles for the treatment of acne.

Acne is a common chronic inflammatory disorder of the sebaceous gland in the hair follicle. Commonly used external medications cause skin irritation, and the transdermal capacity is weak, making it difficult to penetrate the cuticle skin barrier. Hair follicles can aid in the breakdown of this barrier. As nanomaterials progress, polymer-based nanocarriers are routinely used for hair follicle drug delivery to treat acne and other skin issues. Based on the physiological and anatomical characteristics of hair follicles, this paper discusses factors affecting hair follicle delivery by polymer nanocarriers, summarizes the common combination technology to improve the targeting of hair follicles by carriers, and finally reviews the most recent research progress of different polymer nanodrug-delivery systems for the treatment of acne by targeting hair follicles.

The relationship and pathways between resting-state EEG, physical function, and cognitive function in older adults.

OBJECTIVE: Based on resting-state electroencephalography (EEG) evidence, this study aimed to explore the relationship and pathways between EEG-mediated physical function and cognitive function in older adults with cognitive impairment. METHODS: A total of 140 older adults with cognitive impairment were recruited, and data on their physical function, cognitive function, and EEG were collected. Pearson correlation analysis, one-way analysis of variance, linear regression analysis, and structural equation modeling analysis were conducted to explore the relationships and pathways among variables. RESULTS: FP1 theta (effect size = 0.136, 95% CI: 0.025-0.251) and T4 alpha2 (effect size = 0.140, 95% CI: 0.057-0.249) were found to significantly mediate the relationship. The direct effect (effect size = 0.866, 95% CI: 0.574-1.158) and total effect (effect size = 1.142, 95% CI: 0.848-1.435) of SPPB on MoCA were both significant. CONCLUSION: Higher physical function scores in older adults with cognitive impairment were associated with higher cognitive function scores. Left frontal theta and right temporal alpha2, as key observed indicators, may mediate the relationship between physical function and cognitive function. It is suggested to implement personalized exercise interventions based on the specific physical function of older adults, which may delay the occurrence and progression of cognitive impairment in older adults with cognitive impairment.

Light absorption enhancement of black carbon and its impact factors during winter in a megacity of the Sichuan Basin, China.

Carbonaceous aerosols play a vital role in global climate patterns due to their potent light absorption capabilities. However, the light absorption enhancement effect (Eabs) of black carbon (BC) is still subject to great uncertainties due to factors such as the mixing state, coating material, and particle size distribution. In this study, fine particulate matter (PM2.5) samples were collected in Chengdu, a megacity in the Sichuan Basin, during the winter of 2020 and 2021. The chemical components of PM2.5 and the light absorption properties of BC were investigated. The results revealed that secondary inorganic aerosols and carbonaceous aerosols were the dominant components in PM2.5. Additionally, the aerosol filter filtration-dissolution (AFD) treatment could improve the accuracy of measuring elemental carbon (EC) through thermal/optical analysis. During winter in Chengdu, the absorption enhancement values of BC ranged between 1.56 and 2.27, depending on the absorption wavelength and the mixing state of BC and non-BC materials. The presence of internally mixed BC and non-BC materials significantly contributed to Eabs, accounting for an average of 68 % at 405 nm and 100 % at 635 nm. The thickness of the BC coating influenced Eabs, displaying an increasing-then-decreasing trend. This trend was primarily attributed to the hygroscopic growth and dehydration shrinkage of particulate matter. Nitrate, as the major component of BC coating, played a crucial role in the lensing effect and exhibited fast growth during variation in Eabs. By combining the results from PMF, we identified the secondary formation and vehicle emission as the primary contributors to Eabs. Consequently, this study can provide valuable insights into the optical parameters, which are essential for assessing the environmental quality, improving regional atmospheric conditions, and formulating effective air pollution control strategies.

Recent advances in cancer cell bionic nanoparticles for tumour therapy.

Nanoparticle-based drug delivery systems have found extensive use in delivering oncology therapeutics; however, some delivery vehicles still exhibit rapid immune clearance, lack of biocompatibility and insufficient targeting. In recent years, bionanoparticles constructed from tumour cell membranes have gained momentum as tumour-targeting therapeutic agents. Cancer cell membrane-coated nanoparticles (CCMCNPs) typically consist of a drug-loaded nanoparticle core coated with cancer cell membrane. CCMCNPs retain homologous tumour cell surface antigens, receptors and proteins, and it has been shown that the modified nanoparticles exhibit better homologous targeting, immune escape and biocompatibility. CCMCNPs are now widely used in a variety of cancer treatments, including photothermal, photodynamic and sonodynamic therapies, chemotherapy, immunotherapy, chemodynamical therapy or other combination therapies. This article presents different therapeutic approaches using multimodal antitumour therapy-combination of two or more therapies that treat tumours synergistically-based on tumour cell membrane systems. The advantages of CCMCNPs in different cancer treatments in recent years are summarised, thus, providing new strategies for cancer treatment research.

Polyphosphazene nanodrugs for targeting delivery and inflammation responsive release of curcumin to treat acute lung injury by effectively inhibiting cytokine storms.

An excessive inflammatory response induced by cytokine storms is the primary reason for the deterioration of patients with acute lung injury (ALI). Though natural polyphenols such as curcumin (CUR) have anti-inflammation activity for ALI treatment, they often have limited efficacy due to their poor solubility in water and oxidising tendency. This study investigates a highly cross-linked polyphosphazene nano-drug (PHCH) developed by copolymerisation of CUR and acid-sensitive units (4-hydroxy-benzoic acid (4-hydroxy-benzylidene)-hydrazide, D-HBD) with hexachlorotripolyphosphonitrile (HCCP) for improved treatment of ALI. PHCH can prolong the blood circulation time and targeted delivery into lung inflammation sites by enhancing CUR's water dispersion and anti-oxidant properties. PHCH also demonstrates the inflammation-responsive release of CUR in an inflammation environment due to the acid-responsive degradation of hydrazine bonds and triphosphonitrile rings in PHCH. Therefore, PHCH has a substantial anti-inflammation activity for ALI treatment by synergistically improving CUR's water-solubility, bioavailability and biocompatibility. As expected, PHCH attenuates the cytokine storm syndrome and alleviates inflammation in the infected cells and tissues by down-regulating several critical inflammatory cytokines (TNF-α, IL-1ß, and IL-8). PHCH also decreases the expression of p-p65 and C-Caspase-1, inhibiting NLRP3 inflammasomes and suppressing NF-κB signalling pathways. The administrated mice experiments confirmed that PHCH accumulation was enhanced in lung tissue and showed the efficient scavenging ability of reactive oxygen species (ROS), effectively blocking the cytokine storm and alleviating inflammatory damage in ALI. This smart polyphosphazene nano-drug with targeting delivery property and inflammation-responsive release of curcumin has excellent potential for the clinical treatment of various inflammatory diseases, including ALI.

Curcumin-Containing polyphosphazene nanodrug for Anti-Inflammation and nerve regeneration to improve functional recovery after spinal cord injury.

The microenvironment of excessive inflammation and the activation of apoptotic signals are primary barriers to neurological recovery following spinal cord injury (SCI). Thus, long-lasting anti-inflammation has become an effective strategy to navigate SCI. Herein, a curcumin (CUR)-containing nanosystem (FCTHPC) with high drug loading efficiency was reported via assembling hydrophobic CUR into cross-linked polyphosphazene (PPZ), and simultaneous loading and coordinating with porous bimetallic polymers for greatly enhanced the water-solubility and biocompatibility of CUR. The nanosystem is noncytotoxic when directing its biological activities. By inhibiting the expression of pro-inflammatory factors (IL-1ß, TNF-α and IL-6) and apoptotic proteins (C-caspase-3 and Bax/Bcl-2), which may be accomplished by activating the Wnt/ß-catenin pathway, the versatile FCTHPC can significantly alleviate the damage to tissues and cells caused by inflammation and apoptosis in the early stage of SCI. In addition, the long-term in vivo studies had demonstrated that FCTHPC could effectively inhibit the formation of glial scars, and simultaneously promote nerve regeneration and myelination, leading to significant recovery of spinal cord function. This study emphasises the promise of the biocompatible CUR-based nanosystem and provides a fresh approach to effectively treat SCI.

Correlates of physical activity levels, muscle strength, working memory, and cognitive function in older adults.

Objective: To explore the relationship between physical activity level, muscle strength, working memory and cognitive function in older adults. Methods: A cross-sectional research design was employed to recruit 120 older adults individuals aged 70 and above. Participants were asked to complete the International Physical Activity Questionnaire-Short Form and the Montreal Cognitive Assessment Scale. Data on variables such as grip strength and performance on the N-back task were collected. Data analysis involved the use of independent samples t-tests, χ2 tests, linear regression analysis, Pearson correlation analysis, and one-way analysis of variance (ANOVA). Results: The detection rate of cognitive dysfunction in older adults was 53.211%; 1-back correct rate had an explanatory power of 11.6% for the cognitive function scores of older adults (R2 = 0.116, p < 0.001); grip strength showed a significant positive correlation with 1-back correct rate (r = 0.417, p < 0.001), and was significantly correlated with the 0-back response time (r = -0.478), 1 -back response time (r = -0.441) were significantly negatively correlated (p < 0.001); physical activity level was significantly positively correlated with grip strength (r = 0.559, p < 0.001), and the difference in grip strength among older adults with different physical activity levels was statistically significant (F = 19.685, p < 0.001). Conclusion: Physical activity level, muscle strength, working memory, and cognitive function are closely related in older adults, and the relational pathway of physical activity → muscle strength → working memory → cognitive function may serve as a useful addition to promote the field of cognitive research in older adults. To identify and prevent cognitive decline in older adults, physical activity questionnaires, grip strength tests, and 1-back task tests can be extended to nursing homes and communities.

Systematic review and meta-analysis of the effects of exercise on depression in adolescents.

BACKGROUND: Depression is widespread among adolescents and seriously endangers their quality of life and academic performance. Developing strategies for adolescent depression has important public health implications. No systematic review on the effectiveness of physical exercise for adolescents aged 12-18 years with depression or depressive symptoms has previously been conducted. This study aims to systematically evaluate the effect of physical exercise on adolescent depression in the hope of developing optimum physical exercise programs. METHODS: Nine major databases at home and abroad were searched to retrieve randomized controlled trials (RCTs) on exercise interventions among adolescents with depression or depressive symptoms. The retrieval period started from the founding date of each database to May 1, 2021. The methodological quality of the included articles was evaluated using the modified PEDro scale. A meta-analysis, subgroup analysis, sensitivity analysis, and publication bias tests were then conducted. RESULTS: Fifteen articles, involving 19 comparisons, with a sample size of 1331, were included. Physical exercise significantly reduced adolescent depression (standardized mean difference [SMD] = - 0.64, 95% CI - 0.89, - 0.39, p < 0.01), with a moderate effect size, in both adolescents with depression (SMD = -0.57, 95% CI - 0.90, - 0.23, p < 0.01) and adolescents with depressive symptoms (SMD = - 0.67, 95% CI - 1.00, - 0.33, p < 0.01). In subgroups of different depression categories (depression or depressive symptoms), aerobic exercise was the main form of exercise for the treatment of adolescents with depression. For adolescents with depression, interventions lasting 6 weeks, 30 min/time, and 4 times/week had optimum results. The effects of aerobic exercise and resistance + aerobic exercise in the subgroup of adolescents with depressive symptoms were significant, while the effect of physical and mental exercise (yoga) was not significant. For adolescents with depressive symptoms, aerobic exercise lasting 8 weeks, 75-120 min/time, and 3 times/week had optimum results. Physical exercise with moderate intensity is a better choice for adolescents with depression and depressive symptoms. CONCLUSIONS: Physical exercise has a positive effect on the improvement of depression in adolescents. The protocol for this study was registered with INPLASY (202170013). DOI number is 10.37766/inplasy2021.7.0013. Registration Date:2021.7.06.

Cotyledon loss of Astragalus membranaceus hindered seedling establishment through mineral element reallocation and carbohydrate depletion.

Tissue loss of plants caused by herbivores is very common in nature. As the storage and first photosynthetic organ, the loss of cotyledon severely impacts dicot seedling establishment and the subsequent growth. However, it is still not clear how plants adjust their metabolic strategy in response to cotyledon loss. In this study, we employed ICP-OES, GC and LC-MS to examine the effects of cotyledon removal (RC1: remove one cotyledon, RC2: remove two cotyledon) on mineral element distribution and metabolite changes in a traditional Chinese herbal plant, Astragalus membranaceus. The results showed that cotyledon removal had a greater effect on shoot than root growth. Specifically, RC2 revealed a more serious impact on shoot growth than RC1. Microelement Mn and Na in shoot increased more in RC2 than RC1. Macroelement K and microelement B in root increased in RC2. The metabolite results in shoot showed that sugars related to galactose metabolism reduced while amino acids significantly increased in RC2. In root, sugars related to fructose and mannose metabolism decreased in both RC1 and RC2 while most flavonoids increased in RC2. It can be concluded that cotyledon removal triggered different metabolic strategies in both root and shoot. In shoot, more Mn was absorbed to improve the lowered photosynthetic efficiency. Meanwhile, increased Na may have promoted carbohydrate consumption and amino acid synthesis, thereby maintaining shoot growth. In root, K and B participation in cell division and expansion increased, as well as the delivery and metabolism of carbohydrates, to maintain root system growth.

Recent advances in the application of multiplex genome editing in Saccharomyces cerevisiae.

Saccharomyces cerevisiae is a widely used microorganism and a greatly popular cell factory for the production of various chemicals. In order to improve the yield of target chemicals, it is often necessary to increase the copy numbers of key genes or engineer the related metabolic pathways, which traditionally required time-consuming repetitive rounds of gene editing. With the development of gene-editing technologies such as meganucleases, TALENs, and the CRISPR/Cas system, multiplex genome editing has entered a period of rapid development to speed up cell factory optimization. Multi-copy insertion and removing bottlenecks in biosynthetic pathways can be achieved through gene integration and knockout, for which multiplexing can be accomplished by targeting repetitive sequences and multiple sites, respectively. Importantly, the development of the CRISPR/Cas system has greatly increased the speed and efficiency of multiplex editing. In this review, the various multiplex genome editing technologies in S. cerevisiae were summarized, and the principles, advantages, and the disadvantages were analyzed and discussed. Finally, the practical applications and future prospects of multiplex genome editing were discussed. KEY POINTS: • The development of multiplex genome editing in S. cerevisiae was summarized. • The pros and cons of various multiplex genome editing technologies are discussed. • Further prospects on the improvement of multiplex genome editing are proposed.

Methane Saline Ameliorates Traumatic Brain Injury through Anti-Inflammatory, Antiapoptotic, and Antioxidative Effects by Activating the Wnt Signalling Pathway.

OBJECTIVE: Methane saline (MS) can be used to treat many diseases via its anti-inflammatory, antiapoptotic, and antioxidative activities. However, to date, there is no published evidence as to whether MS has any effect on traumatic brain injury (TBI). The Wnt signalling pathway regulates cell proliferation, differentiation, migration, and apoptosis; however, whether the Wnt signalling pathway regulates any effect of MS on TBI is unknown. This study was designed to explore the role of MS in the treatment of TBI and whether the Wnt pathway is involved. METHODS: Sprague-Dawley rats were randomly divided into five groups: sham, TBI, TBI+10 ml/kg MS, TBI+20 ml/kg MS, and TBI+30 ml/kg MS. After induction of TBI, MS was injected intraperitoneally once daily for seven consecutive days. Neurological function was evaluated by the Neurological Severity Score (NSS) at 1, 7, and 14 days after TBI. Haematoxylin-eosin (HE) staining, inflammatory factors, neuron-specific enolase (NSE) staining, oxidative stress, and cell apoptosis were measured and compared 14 d after TBI to identify the optimal dose of MS and to investigate the effect of MS on TBI. In the second experiment, Sprague-Dawley rats were randomly divided into four groups: sham, TBI, TBI+20 ml/kg MS, and TBI+20 ml/kg MS+Dickkopf-1 (DKK-1, a specific inhibitor of the Wnt pathway). NSE, caspase-3, superoxide dismutase (SOD), Wnt3a, and ß-catenin were detected by real-time PCR and Western blotting. The results from each group were compared 14 d after TBI to determine the regulatory role of the Wnt pathway. RESULTS: Methane saline significantly inhibited inflammation, oxidative stress, and cell apoptosis, thus protecting neurons within 14 days of TBI. The best treatment effect against TBI was obtained with 20 ml/kg MS. When the Wnt pathway was inhibited, the treatment effect of MS was impaired. CONCLUSION: Methane saline ameliorates TBI through its anti-inflammatory, antiapoptotic, and antioxidative effects via activation of the Wnt signalling pathway, which plays a part but is not the only mechanism underlying the effects of MS. Thus, MS may be a novel strategy for treating TBI.

Exercise protects against spinal cord injury through miR-21-mediated suppression of PDCD4.

Spinal cord injury (SCI) can lead to different levels of paraplegia. Studies have shown that exercise exerts wide protective effects against various diseases, and microRNAs (miRNAs) are involved in its beneficial effects. However, the specific role of miRNAs in the protective effects of exercise against SCI remains unclear. Here, we showed that exercise exerted protective effects against SCI as evidenced by increased locomotor activity and spinal cord cell survival in rats with SCI. Exercise upregulated circulating miR-21, detected by miRNA microarray, in rats with SCI. Treating SCI rats with agomiR-21 upregulated circulating miR-21 and exerted protective effects against SCI. Additionally, downregulating miR-21 using antagomir-21 abolished the protective effects of exercise on SCI. Programmed cell death protein 4 (PDCD4) was found to be the target of miR-21. These results suggested that exercise protects against SCI, at least partly, through miR-21-mediated suppression of PDCD4.

Exercise, brain plasticity, and depression.

Depression is a common mental disorder characterized by high incidence, high disability, and high fatality, causing great burden to the society, families, and individuals. The changes in brain plasticity may be a main reason for depression. Recent studies have shown that exercise plays a positive role in depression, but systematic and comprehensive studies are lacking on brain plasticity changes in depression. To further understand the antidepressive effect of exercise and the changes in brain plasticity, we retrieved related literatures using key words "depression," "depressive disorder," "exercise," "brain plasticity," "brain structure," and "brain function" from the database of Web of Science, PubMed, EBSCO host, and CNKI, hoping to provide evidence for exercise in preventing and treating depression. Increase in exercise has been found negatively correlated with the risk of depression. Randomized controlled experiments have shown that aerobic exercise, resistance exercise, and mind-body exercise can improve depressive symptoms and levels. The intensity and long-term effect of exercise are now topical research issues. Exercise has been proven to reshape the brain structure of depression patients, activate the function of related brain areas, promote behavioral adaptation changes, and maintain the integrity of hippocampal and white matter volume, thus improving the brain neuroprocessing and delaying cognitive degradation in depression patients. Future studies are urgently needed to establish accurate exercise prescriptions for improving depressive symptoms, and studies on different depressive populations and studies using multimodal brain imaging combined with multiple analytical methods are also needed.

Protective effect of brain-derived neurotrophic factor and neurotrophin-3 overexpression by adipose-derived stem cells combined with silk fibroin/chitosan scaffold in spinal cord injury.

Objectives: Spinal cord injury (SCI) is a most debilitating traumatic injury, and cytotherapy is a promising alternative treatment strategy. Here we investigated the effect and mechanism of adipose-derived stem/stromal cells (ASCs) with overexpressing brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT3) (BDNF-NT3) in combination with silk fibroin/chitosan scaffold (SFCS) in SCI.Methods: Female Sprague-Dawley rats were used as an SCI model. SFCS,SFCS and ASCs, or ASCs overexpressing NT3, BDNF, and BDNF-NT3 were implanted into SCI rats. Basso, Beattie, and Bresnahan score, pathological changes, and spinal cord tissue and nerve fiber morphology were observed and assayed. GAP-43, GFAP, and caspase-3 expression was determined using immunohistochemistry and western blotting.Results: Smoother spinal cords, less scar tissue, and lower inflammatory activity were found in the SFCS, SFCS and ASCs, ASCs with NT3, BDNF, and BDNF-NT3 overexpression treatment than in the untreated SCI rat groups. Increasing formation of nerve fibers was observed in the above groups in order. GAP-43 expression significantly increased, while GFAP and caspase-3 expression significantly decreased. These results indicated obvious alleviation in pathological changes and BDNF-NT3 overexpression in ASCs combined with SFCS treatment in SCI rats.Conclusion: Thus, BDNF-NT3 overexpression from ASCs with SFCS had synergistic neuroprotective effects on SCI and may be a treatment option for SCI.

Effects of Tai Chi Chuan on Cognitive Function in Older Adults with Cognitive Impairment: A Systematic and Meta-Analytic Review.

This systematic and meta-analytic review aimed to investigate the effects of Tai Chi Chuan (TCC) on the cognitive function of the elderly with cognitive impairment and to analyze the moderators of these effects. We searched eight electronic databases for randomized controlled trials on the effects of TCC on cognitive function, published up to June 14, 2020. The PEDro scale was used to evaluate the methodological quality of the included literature. Stata14.0 software was used for meta-analysis, subgroup analysis, and publication bias testing. A total of 19 studies and 1,970 samples were included. The methodological quality of the included literature was fair to good, and there was no publication bias. Overall, the research shows that the effect of TCC on the elderly with cognitive impairment is statistically significant (SMD = 0.31, p < 0.0001). Five of the cognitive function subdomains were significant moderators [Q (5) = 15.66, p=0.008], and the effect size (ES) was the largest for global cognitive function (SMD = 0.41), followed by executive function (SMD = 0.33), memory (SMD = 0.31), and verbal fluency (SMD = 0.27). Regarding the exercise prescription variables, results were significantly moderated by the length of exercise training [Q (2) = 6.00, p=0.05], with ESs largest for moderate length (SMD = 0.41), followed by short length (SMD = 0.40) and long length (SMD = 0.29). However, the results were not moderated by session time or frequency. TCC can improve multiple cognitive functions of the elderly with cognitive impairment. The intervention effects are moderated by exercise length, but not by exercise session time and frequency.

miR-21 deficiency contributes to the impaired protective effects of obese rat mesenchymal stem cell-derived exosomes against spinal cord injury.

The therapeutic effect of stem cell transplantation in traumatic spinal cord injury (SCI) has been extensively studied these days, and evidence has shown that stem cell-derived exosomes and exosome-shuttled miRNA (e.g. miR-21) contribute to the protective effects of stem cell transplantation against SCI. It has been reported that obesity, a prevalent metabolic disorder, reshapes stem cells and their extracellular vesicles. However, the effects of exosomes derived from obese rat stem cells on SCI and its underlying mechanism remain unknown. Here, we examined the effects of exosomes derived from obese rat mesenchymal stem cells (MSCs) on SCI, and tested the role of miR-21 in their effects. We found that exosomes derived from obese rat MSCs showed decreased miR-21 levels and did not exert protective effects against SCI. Overexpression of miR-21 in obese rat MSCs restored the protective effects of exosomes purified from obese rat MSCs against SCI. In addition, obese rat MSCs showed insulin resistance, and MSC insulin resistance decreased miR-21 levels in its secreted exosomes. These results suggested that miR-21 deficiency in obese rat MSCs contributes to the impaired protective effects of obese rat MSCs-derived exosomes against SCI, and further reinforced the notion that miR-21 is a potential molecule for treatment of SCI.

Air stagnation and its impact on air quality during winter in Sichuan and Chongqing, southwestern China.

The Sichuan and Chongqing regions suffer from severe haze weather in winter due to the unfavourable atmospheric diffusion conditions. Reanalysis and precipitation datasets were applied in this study to calculate and distinguish air stagnation events using a developed criterion, and the impacts of the occurrence of air stagnation events on air quality were analysed in combination with the PM2.5 concentration data for the winters of 2013-2016. The highest occurrence frequency of air stagnation events was observed in 2013, and the lowest, 2015. The meteorological conditions during winter in the Sichuan Basin were inclined to form unfavourable atmospheric diffusion conditions, and the occurrence frequency of air stagnation days was up to 76.6% on average during the four winters. The effects of air stagnation events on air quality were most obvious in the western and southern Sichuan Basin. The mean concentrations of PM2.5 during air stagnation days were higher by 41.9% than those during non-air stagnation days. The PM2.5 concentrations were adjusted using the favourable atmospheric diffusion conditions in 2015 as a baseline to quantify the PM2.5 contribution to the improvement of air quality in the other years, which revealed that the level of PM2.5 in the Sichuan and Chongqing regions was declining at a rate of approximately 10.7% overall during the winters of 2013-2016, implying that the air pollutant reduction measures have been highly effective. Furthermore, the occurrence frequency of air stagnation days and events were increased in recent ten years of 2007-2016, with linear slopes of 0.61yr-1 and 0.26yr-1, respectively. The study revealed that the government might face a greater challenge in improving the air quality over winter and should pay more attention to reduction of pollutant emission in areas of Chengdu, Chongqing and cities in the south of the Sichuan Basin.

Heavy pollution episodes, transport pathways and potential sources of PM2.5 during the winter of 2013 in Chengdu (China).

Air mass concentration data from 8 environmental quality monitoring sites and meteorological data of Chengdu from 1 December 2013 to 28 February 2014 were used in this study. Chengdu suffered five continuous heavy pollutions during this winter due to the basin terrain and the meteorological conditions of low wind speed, low precipitation and high relative humidity. Analysing the hourly resolution time series of pollutants' concentrations, variation of PM2.5 in the urban area followed a growing "saw-tooth cycle" pattern during the heavy pollution, with a daily cycle of bimodal distribution. The massive letting-off of fireworks within a short period of time on the Eve of the Lunar New Year under the unfavourable diffusion conditions resulted in an extreme pollution event. The sharply rising Longmen-Qionglai Mountains to the west of the Sichuan Basin not only acted as a huge barrier to block the air mass from the east but also favoured the formation of a local circulation. The cluster analysis of back trajectories revealed that up to 77% of them came from the inner part of the Basin. Combining the concentration data of PM2.5 with air mass back trajectories, a potential source contribution function (PSCF) model and a concentration-weighted trajectory (CWT) method were used to evaluate the transport pathways and sources over PM2.5 of Chengdu, revealing that the main potential sources of PM2.5 were located in southeast cities and the western margin of the Sichuan Basin. The result provided advice for the government to take measures in improving air quality.

CuInS2 nanotube array on indium tin oxide: synthesis and photoelectrochemical properties.

CuInS(2) nanotube (NT) arrays were synthesized on indium tin oxide (ITO) substrates for the first time using a successive ionic layer absorption and reaction (SILAR) process with self-dissolved ZnO nanowire (NW) templates. The p-type CuInS(2) NT array shows promising conversion efficiency in a photoelectrochemical cell with polysulfide electrolyte.