The effects of demand-resource relationship on work-family conflict under Chinese culture: a cross-sectional study.

Chinese work and lifestyle are undergoing dramatic changes caused by constantly changing technology and new policies. The demand-resource dynamic relationship, which leads to work-family conflict (WFC), has become increasingly complicated. However, very little is known about the combined effects of different factors from work and family spheres on WFC. This study aims to explore (1) the discrepancy between fit and misfit, (2) the discrepancy of the different degrees of fit, and (3) the discrepancy of the different degrees of misfit from two perspectives: work demand-family resource and work resource-family demand. Data were collected from 745 individuals in China and analyzed using polynomial regression and response surface. The results demonstrate that individuals having low work demand-high family resources experience the lowest WFC, and the fit between work demands and family resources impacts the conflict in a U way. Similarly, high work resource-low family demand results in the lowest WFC; however, the fit between work resources and family demands has negative effects on the conflict. This study took factors from both family and work domains into consideration and explored the effect of their interaction on WFC. By examining the dynamic relationship between demands and resources, adjustments can be made in both domains simultaneously, providing more flexible guidance for management practices that reduce WFC.

Ecological comparison of six countries in two waves of COVID-19.

Objective: The purpose of this study is to provide experience and evidence support for countries to deal with similar public health emergencies such as COVID-19 by comparing and analyzing the measures taken by six countries in epidemic prevention and control. Methods: This study extracted public data on COVID-19 from the official website of various countries and used ecological comparative research methods to compare the specific situation of indicators such as daily tests per thousand people, stringency index, and total vaccinations per hundred people in countries. Results: The cumulative death toll in China, Germany and Australia was significantly lower than that in the United States, South Africa and Italy. Expanding the scale of testing has helped control the spread of the epidemic to some extent. When the epidemic situation is severe, the stringency index increases, and when the epidemic situation tends to ease, the stringency index decreases. Increased vaccination rates, while helping to build an immune barrier, still need to be used in conjunction with non-drug interventions. Conclusion: The implementation of non-drug interventions and vaccine measures greatly affected the epidemic prevention and control effect. In responding to public health emergencies such as the COVID-19 epidemic, countries should draw on international experience, closely align with their national conditions, follow the laws of epidemiology, actively take non-drug intervention measures, and vigorously promote vaccine research and development and vaccination.

Disparities and effectiveness of COVID-19 vaccine policies in three representative European countries.

OBJECTIVE: The aim of this study was to examine the Coronavirus disease 2019(COVID-19) vaccine policies disparities and effectiveness in Germany, Denmark and Bulgaria, with a view to providing lessons for global vaccination and response to possible outbreak risks. METHODS: This study analyzed big data through public information on the official websites of the Ministries of Health of the European Union, Germany, Denmark and Bulgaria and the official websites of the World Health Organization. We systematically summarized the COVID-19 vaccine policies of the three countries, and selected the following six indicators for cross-cutting vaccination comparisons: COVID-19 vaccine doses administered per 100 people, COVID-19 vaccination rate, the share of people with fully vaccinated, the share of people only partly vaccinated, cumulative confirmed COVID-19 cases per million, cumulative confirmed COVID-19 deaths per million. Meanwhile, we selected the following four indicators for measuring the effectiveness of COVID-19 vaccine policy implementation: daily cases per million, daily deaths per million, the effective reproduction rate (Rt), the moving-average case fatality rate (CFR). RESULTS: Although these three EU countries had the same start time for vaccination, and the COVID-19 vaccine supply was coordinated by the EU, there are still differences in vaccination priorities, vaccination types, and vaccine appointment methods. Compared to Germany and Denmark, Bulgaria had the least efficient vaccination efforts and the worst vaccination coverage, with a vaccination rate of just over 30% as of June 2023, and the maximum daily deaths per million since vaccination began in the country was more than three times that of the other two countries. From the perspective of implementation effect, vaccination has a certain effect on reducing infection rate and death rate, but the spread of new mutant strains obviously aggravates the severity of the epidemic and reduces the effectiveness of the vaccine. Among them, the spread of the Omicron mutant strain had the most serious impact on the three countries, showing an obvious epidemic peak. CONCLUSIONS: Expanding vaccination coverage has played a positive role in reducing COVID-19 infection and mortality rates and stabilizing Rt. Priority vaccination strategies targeting older people and at-risk groups have been shown to be effective in reducing COVID-19 case severity and mortality in the population. However, the emergence and spread of new variant strains, and the relaxation of epidemic prevention policies, still led to multiple outbreaks peaking. In addition, vaccine hesitancy, mistrust in government and ill-prepared health systems are hampering vaccination efforts. Among the notable ones are divergent types of responses to vaccine safety issue could fuel mistrust and hesitancy around vaccination. At this stage, it is also necessary to continue to include COVID-19 vaccination in priority vaccination plans and promote booster vaccination to prevent severe illness and death. Improving the fairness of vaccine distribution and reducing the degree of vaccine hesitancy are the focus of future vaccination work.

High-Performance All-Small-Molecule Organic Solar Cells Fabricated via Halogen-Free Preparation Process.

Small-molecule organic photovoltaic materials attract more attention attributing to their precisely defined structure, ease of synthesis, and reduced batch-to-batch variations. The majority of all-small-molecule organic solar cells (ASM-OSCs) have traditionally relied on halogenated solvents for dissolving photovoltaic materials as well as used for the additives or solvent vapor annealing. However, these halogen-based processes pose risks to the environment and human health, potentially impeding future commercial production. Herein, we conducted an investigation into the impact of various nonhalogen solvents on the performance of the devices. By selecting the high boiling point solvent toluene, we achieved a desirable phase separation and stable morphology characterized by fibrous crystals within the blend film. Consequently, the power conversion efficiencies of 14.4 and 11.7% were obtained from H31:Y6-based small-area (0.04 cm2) and large-area (1 cm2) devices with steady performance, respectively. This study successfully demonstrated the fabrication of ASM-OSCs without employing halogenated solvent processes, thus offering promising prospects for the commercial production of ASM-OSCs.

Scinderin Promotes Hydrogen Peroxide-induced Lens Epithelial Cell Injury in Age-related Cataract.

BACKGROUND: Scinderin (SCIN) is a calcium-dependent protein implicated in cell growth and apoptosis by regulating actin cleavage and capping. In this study, we investigated the role of SCIN in hydrogen peroxide-induced lens epithelial cell (LEC) injury related to age-related cataract (ARC). METHODS: Anterior lens capsules from ARC patients were collected to examine SCIN expression levels. Immortalized human LEC cell line SRA01/04 and lens capsules freshly isolated from mice were induced by H2O2 to mimic the oxidative stress in ARC. The role of SCIN was investigated by gain-of-function (overexpression) and loss-offunction (knockdown) experiments. Flow cytometry (FCM) and Western-blot (WB) assays were performed to investigate the effect of SCIN on apoptosis. The oxidative stress (OS) was examined by detecting malondialdehyde (MDA) level, superoxide dismutase (SOD) and catalase (CAT) activity. The interaction between SCIN mRNA and miR-489-3p was predicted by StarBase and miRDB databases and validated by luciferase reporter activity assay. RESULTS: SCIN was significantly elevated in cataract samples, and the expression levels were positively correlated with the nuclear sclerosis grades. SCIN overexpression promoted OS and apoptosis in H2O2-induced SRA01/04 cells, while SCIN silencing showed the opposite effect. We further showed that miR-489-3p was a negative regulator of SCIN. miR-489-3p overexpression suppressed apoptosis and OS in H2O2-induced SRA01/04 cells by targeting SCIN. CONCLUSION: Our study identified SCIN as an upregulated gene in ARC, which is negatively regulated by miR-489-3p. Targeting miR-489-3p/SCIN axis could attenuate OS-induced apoptosis in LECs.

Comparison of COVID-19 vaccine policies and their effectiveness in Korea, Japan, and Singapore.

BACKGROUND: This study aimed to analyze coronavirus disease 2019 (COVID-19)vaccine policies and effectiveness in Korea, Japan, and Singapore, thereby providing empirical experience for vaccination and response to similar public health emergencies. METHODS: The study systematically summarized the COVID-19 vaccine policies in Korea, Japan, and Singapore through public information from the Our World in Data website and the official websites of the Ministries of Health in these three countries.Total vaccinations, COVID-19 vaccination rates, rates of fully vaccinated, rates of boostervaccinated, and total confifirmed cases were selected for cross-sectional comparison of COVID-19 vaccination in these three countries. Combining the basic characteristics of these three countries, daily cases per million, daily deaths per million, and the effective reproduction rate were calculated to measure the effectiveness of COVID-19 vaccine policies implementation in each of these three countries RESULTS: The countermeasures against the COVID-19 in Korea, Japan, and Singapore, although seemingly different on the surface, have all taken an aggressive approach. There are large similarities in the timing of the start of COVID-19 vaccination, the type of vaccine, how vaccine appointments are made, and whether vaccination are free, and all had high vaccination rates. A systematic comparison of the anti-epidemic practices in the three East Asian countries revealed that all three countries experienced more than one outbreak spike due to the spread of new mutant strains after the start of mass vaccination with COVID-19 vaccination, but that vaccination played a positive role in reducing the number of deaths and stabilizing the effective reproduction rate. CONCLUSIONS: This study comparatively analyzed the COVID-19 vaccine policies and their effects in South Korea, Japan, and Singapore, and found that there is a common set of logical combinations behind the seemingly different strategies of these three countries. Therefore, in the process of combating COVID-19, countries can learn from the successful experience of combating the epidemic and continue to strengthen the implementation of vaccination programs, as well as adjusting public perceptions to reduce the level of vaccine hesitancy, enhance the motivation for vaccination, and improve the coverage of COVID-19 vaccine based on different cultural factors, which remains the direction for future development.

Structural basis for the development of potential inhibitors targeting FadD23 from Mycobacterium tuberculosis.

Sulfolipid-1 (SL-1) is a lipid that is abundantly found in the cell wall of Mycobacterium tuberculosis (Mtb). MtbFadD23 is crucial in the SL-1 synthesis pathway. Previously, 5'-O-[N-(11-phenoxyundecanoyl)sulfamoyl]adenosine (PhU-AMS) has been shown to be a general inhibitor of fatty-acid-adenylating enzymes (FadDs) in Mtb. However, the fatty acyl-AMP ligase (FAAL) class of FadDs, which includes MtbFadD23, appears to be functionally nonredundant in the production of multiple fatty acids. In this study, the ability of PhU-AMS to bind to MtbFadD23 was examined under in vitro conditions. The crystal structure of the MtbFadD23-PhU-AMS complex was determined at a resolution of 2.64 Å. Novel features were identified by structural analysis and comparison. Although PhU-AMS could bind to MtbFadD23, it did not inhibit the FAAL adenylation activity of MtbFadD23. However, PhU-AMS improved the main Tm value in a differential scanning fluorimetry assay, and a structural comparison of MtbFadD23-PhU-AMS with FadD32 and PA1221 suggested that PhU-AMS blocks the loading of the acyl chain onto Pks2. This study sheds light on the structure-based design of specific inhibitors of MtbFadD23 and general inhibitors of FAALs.

Deep Learning-Based Recognition of Cervical Squamous Interepithelial Lesions.

Cervical squamous intraepithelial lesions (SILs) are precursor lesions of cervical cancer, and their accurate diagnosis enables patients to be treated before malignancy manifests. However, the identification of SILs is usually laborious and has low diagnostic consistency due to the high similarity of pathological SIL images. Although artificial intelligence (AI), especially deep learning algorithms, has drawn a lot of attention for its good performance in cervical cytology tasks, the use of AI for cervical histology is still in its early stages. The feature extraction, representation capabilities, and use of p16 immunohistochemistry (IHC) among existing models are inadequate. Therefore, in this study, we first designed a squamous epithelium segmentation algorithm and assigned the corresponding labels. Second, p16-positive area of IHC slides were extracted with Whole Image Net (WI-Net), followed by mapping the p16-positive area back to the H&E slides and generating a p16-positive mask for training. Finally, the p16-positive areas were inputted into Swin-B and ResNet-50 to classify the SILs. The dataset comprised 6171 patches from 111 patients; patches from 80% of the 90 patients were used for the training set. The accuracy of the Swin-B method for high-grade squamous intraepithelial lesion (HSIL) that we propose was 0.914 [0.889-0.928]. The ResNet-50 model for HSIL achieved an area under the receiver operating characteristic curve (AUC) of 0.935 [0.921-0.946] at the patch level, and the accuracy, sensitivity, and specificity were 0.845, 0.922, and 0.829, respectively. Therefore, our model can accurately identify HSIL, assisting the pathologist in solving actual diagnostic issues and even directing the follow-up treatment of patients.

Monte Carlo modeling of hepatic steatosis based on stereology and spatial distribution of fat droplets.

BACKGROUND AND OBJECTIVE: To model hepatic steatosis in adult humans with non-alcoholic fatty liver disease based on stereology and spatial distribution of fat droplets from liver biopsy specimens. METHODS: Histological analysis was performed on 30 adult human liver biopsy specimens with varying degrees of steatosis. Morphological features of fat droplets were characterized by gamma distribution function (GDF) in both two-dimensional (2D) and three-dimensional (3D) spaces from three aspects: 1) size distribution indicating non-uniformity of fat droplets in radius; 2) nearest neighbor distance distribution indicating heterogeneous accumulation (i.e., clustering) of fat droplets; 3) regional anisotropy indicating inter-regional variability in fat fraction (FF). To generalize the morphological description of hepatic steatosis to different FFs, correlation analysis was performed among the estimated GDF parameters and FFs for all specimens. Finally, Monte Carlo modeling of hepatic steatosis was developed to simulate fat droplet distribution in tissue. RESULTS: Morphological features, including size and nearest neighbor distance in 2D and 3D spaces as well as regional anisotropy, statistically captured the distribution of fat droplets by the GDF fit (R2 > 0.54). The estimated GDF parameters (i.e., scale and shape parameters) and FFs were well correlated, with R2 > 0.55. In addition, simulated 3D liver morphological models demonstrated similar sections to real histological samples both visually and quantitatively. CONCLUSIONS: The morphology of hepatic steatosis is well characterized by stereology and spatial distribution of fat droplets. Simulated models demonstrate similar appearances to real histological samples. Furthermore, the model may help understand MRI signal behavior in the presence of liver steatosis.

Plant Defense and Viral Counter-Defense during Plant-Geminivirus Interactions.

Geminiviruses are the largest family of plant viruses that cause severe diseases and devastating yield losses of economically important crops worldwide. In response to geminivirus infection, plants have evolved ingenious defense mechanisms to diminish or eliminate invading viral pathogens. However, increasing evidence shows that geminiviruses can interfere with plant defense response and create a suitable cell environment by hijacking host plant machinery to achieve successful infections. In this review, we discuss recent findings about plant defense and viral counter-defense during plant-geminivirus interactions.

Progress in application of virtual reality in prevention and treatment of childhood obesity / 中国学校卫生

Abstract@#As a new non drug treatment technology, virtual reality technology is commonly available for childhood obesity prevention and treatment. This technology offers a great opportunity to carry out research on parental feeding behavior. Also, its combination with child nutritional education and exercise managementis is gaining popularity. This review summarizes the application progress of virtual reality technology in childhood obesity prevention and treatment, such as parental feeding,children s nutrition education and children s sports management, providing reference for childhood weight management and related research.

Adapting to Lockdown: Exploring Stress Coping Strategies on Short Video Social Media During the COVID-19 Pandemic.

Introduction: The study addresses a gap in research on media use during the COVID-19 pandemic, focusing on the overlooked role of short video social media platforms in stress management. It builds on transactional stress model and coping flexibility to advance the understanding of the strategy-situation fit, particularly the alignment of coping strategies with platform affordances. Methods: Our study investigated the detailed use of short video platforms and coping strategies during the pandemic lockdown through an online survey of 1569 respondents conducted immediately after the lockdown. We characterized lockdown duration as a situational stressor attribute and explored variations in the coping process. Assessing changes in user behavior across the top four Chinese short video platforms, we examined anxiety induced by lockdown and the use of problem-focused and emotion-focused coping strategies. Results: Significant changes in user behavior in response to lockdown-induced stress were observed. Structural model analyses reveal that people employed both coping strategies to manage heightened anxiety, primarily through increased viewing behavior over interaction behavior. Discussion: The findings underscore the positive implications of short video platforms on individual well-being. This study argues for a deeper research focus on coping flexibility within the realm of social media, accompanied by a comprehensive assessment of platform user behavior. Future research should also consider the influence of algorithms on platform functionality.

Coupling of (methane + air)-membrane biofilms and air-membrane biofilms: Treatment of p-nitroaniline wastewater.

Membrane biofilm (MBf) technology is a promising biological water treatment process that combines membrane aeration with biofilms. To expand its application in the treatment of toxic organic wastewater, methane/air gas mixture-MBfs ((CH4 + Air)-MBfs) and air-MBfs were coupled to enhance the treatment of p-nitroaniline (PNA) wastewater. Based on exploration of the membrane permeability of methane and oxygen, a hybrid MBf reactor was constructed, and the degradation characteristics of PNA and the coupling effects of (CH4 + Air)-MBfs and air-MBfs were studied. The permeation flux of methane was found to be 1.114 g/(m2 d) when using a methane/air gas mixture at an aeration pressure of 10 kPa, and this result was better than that when methane was used as the aeration gas alone. Aeration with a methane/air gas mixture provided conditions for realizing aerobic methane oxidation; the aerobic methane oxidation that occurred in the (CH4 + Air)-MBfs promoted the reduction of PNA, and the intermediates of PNA degradation were further degraded by the air-MBfs. At an influent PNA membrane area load of 1.67 g/(m2 d), the PNA removal load reached 187.30 g/(m3 d). The coupling of MBfs took advantage of different matrix-based MBfs and promoted the degradation of PNA by utilizing the synergistic effects of various functional microorganisms.

Lansoprazole-induced osteoporosis via the IP3R- and SOCE-mediated calcium signaling pathways.

BACKGROUND: Many clinical studies have shown a correlation between proton pump inhibitors (PPIs) and osteoporosis or fractures. The purpose of this study was to establish a murine model of chronic oral PPI administration to verify whether PPIs caused bone metabolic impairment and investigate the relevant molecular mechanism underlying the effects of PPIs on MC3T3-E1 murine osteoblasts. METHODS: A lansoprazole-induced bone loss model was used to investigate the damaging effects of PPIs. In vivo, immunohistochemistry, Hematoxylin-Eosin (HE) staining, micro-CT analysis, and blood biochemical analyses were used to evaluate the effect of lansoprazole on bone injury in mice. In vitro, the effects of lansoprazole and related signaling pathways in MC3T3-E1 cells were investigated by CCK-8 assays, EdU assays, flow cytometry, laser confocal microscopy, patch clamping, reverse transcription-quantitative polymerase chain reaction and Western blotting. RESULTS: After 6 months of lansoprazole gavage in ICR mice, the micro-CT results showed that compared with that in the vehicle group, the bone mineral density (BMD) in the high-dose group was significantly decreased (P < 0.05), and the bone microarchitecture gradually degraded. Biochemical analysis of bone serum showed that blood calcium and phosphorus were both decreased (P < 0.01). We found that long-term administration of lansoprazole impaired skeletal function in mice. In vitro, we found that lansoprazole (LPZ) could cause calcium overload in MC3T3-E1 cells leading to apoptosis, and 2-APB, an inhibitor of IP3R calcium release channel and SOCE pathway, effectively blocked increase in calcium caused by LPZ, thus protecting cell viability. CONCLUSIONS: Longterm administration of LPZ induced osteoporotic symptoms in mice, and LPZ triggered calcium increases in osteoblasts in a concentration-dependent manner. Intracellular calcium ([Ca2+]i) persisted at a high concentration, thereby causing endoplasmic reticulum stress (ERS) and inducing osteoblast apoptosis.

Corosolic acid and its structural analogs: A systematic review of their biological activities and underlying mechanism of action.

BACKGROUND: The corosolic acid (CA), also known as plant insulin, is a pentacyclic triterpenoid extracted from plants such as Lagerstroemia speciosa. It has been shown to have anti-diabetic, anti-inflammatory and anti-tumor effects. Its structural analogs ursolic acid (UA), oleanolic acid (OA), maslinic acid (MA), asiatic acid (AA) and betulinic acid (BA) display similar individual pharmacological activities to those of CA. However, there is no systematic review documenting pharmacological activities of CA and its structural analogues. This study aims to fill this gap in literature. PURPOSE: This systematic review aims to summarize the medical applications of CA and its analogues. METHODS: A systematic review summarizes and compares the extraction techniques, pharmacokinetic parameters, and pharmacological effects of CA and its structural analogs. Hypoglycemic effect is one of the key inclusion criteria for searching Web of Science, PubMed, Embase and Cochrane databases up to October 2020 without language restrictions. 'corosolic acid', 'ursolic acid', 'oleanolic acid', 'maslinic acid', 'asiatic acid', 'betulinic acid', 'extraction', 'pharmacokinetic', 'pharmacological' were used to extract relevant literature. The PRISMA guidelines were followed. RESULTS: At the end of the searching process, 140 articles were selected for the systematic review. Information of CA and five of its structural analogs including UA, OA, MA, AA and BA were included in this review. CA and its structural analogs are pentacyclic triterpenes extracted from plants and they have low solubilities in water due to their rigid scaffold and hydrophobic properties. The introduction of water-soluble groups such as sugar or amino groups could increase the solubility of CA and its structural analogs. Their biological activities and underlying mechanism of action are reviewed and compared. CONCLUSION: CA and its structural analogs UA, OA, MA, AA and BA are demonstrated to show activities in lowering blood sugar, anti-inflammation and anti-tumor. Their oral absorption and bioavailability can be improved through structural modification and formulation design. CA and its structural analogs are promising natural product-based lead compounds for further development and mechanistic studies.

Mutations in the regulatory regions result in increased streptomycin resistance and keratinase synthesis in Bacillus thuringiensis.

Keratinases are a group of proteases of great industrial significance. To take full advantage of Bacillus species as an inherent superior microbial producer of proteases, we performed the ribosome engineering to improve the keratinase synthesis capacity of the wild-type Bacillus thuringiensis by inducing streptomycin resistance. Mutant Bt(Str-O) was identified as a stable keratinase overproducer. Comparative characterization of the two strains revealed that, although the resistance to Streptomycin increased by eight-fold in MIC, the mutant's resistance to other commonly used antibiotics was not affected. Furthermore, the mutant exhibited an enhanced keratinase synthesis (1.5-fold) when cultured in a liquid LB medium. In the whole feather degradation experiment, the mutant could secret twofold keratinase into the medium, reaching 640 U/mL per 107 CFU. By contrast, no significant differences were found in the scanning electron microscopic analysis and spore formation experiment. To understand the genetic factors causing these phenotypic changes, we cloned and analyzed the rpsL gene. No mutation was observed. We subsequently determined the genome sequences of the two strains. Comparing the rpsL gene revealed that the emergence of streptomycin resistance was not necessarily dependent on the mutation(s) in the generally recognized "hotspot." Genome-wide analysis showed that the phenotypic changes of the mutant were the collective consequence of the genetic variations occurring in the regulatory regions and the non-coding RNA genes. This study demonstrated the importance of genetic changes in regulatory regions and the effectiveness of irrational ribosome engineering in creating prokaryotic microbial mutants without sufficient genetic information.

Hybrid ZIF-8-90 for Selective Solid-Phase Microextraction of Exhaled Breath from Gastric Cancer Patients.

Metal-organic frameworks (MOFs) are a new kind of microporous materials whose unique properties make them promising as coatings for solid phase microextraction (SPME). However, previous MOF coatings for SPME exclusively focus on single-linker MOFs, and the selective enrichment of polar or nonpolar targets depends on the polarity of linker on the surface of MOFs, which greatly limits the application of MOF coating for SPME in real samples. Here, we report a hybrid MOF-coated stainless steel fiber for SPME of biomarkers in exhaled breath from gastric cancer patients. Zeolitic imidazolate framework-8-90 (ZIF-8-90) possesses the aldehyde groups and methyl groups in the framework as a model MOF, and eight biomarkers (ethanol, acetone, hexanal, hexanol, nonane, isoprene, heptane, and decane) were used as the target analytes. The ZIF-8-90-coated fiber shows high enrichment efficiency for hydrophilic targets and hydrophobic targets, wide linearity (three orders of magnitude), and low detection limits (0.82-2.64 µg L-1). The ZIF-8-90-coated fiber exhibited higher enrichment performance for all the investigated analytes as a result of the synergy of methyl and aldehyde groups, the porous structure, and the suitable pore size of ZIF-8-90 (4-5 Å). The relative standard deviation (RSD) of six repetitions for extractions using the same ZIF-8-90-coated fiber ranged from 2.5 to 7.3%. The reproducibility between the three fibers prepared in parallel varied in the range of 4.8-12% (RSD). The fabricated ZIF-8-90-coated fiber lasted for at least 120 cycles of extraction/desorption/conditioning without an obvious reduction in extraction efficiency and precision. Finally, the developed ZIF-8-90-coated SPME fiber has been successfully used for the analysis of exhaled breath samples from gastric patients with satisfied recoveries (88-106%).

Review of MAC Protocols for Vehicular Ad Hoc Networks.

Vehicular ad hoc networks (VANETs) need to support the timely end-to-end transmissions of safety and non-safety messages. Medium access control (MAC) protocols can ensure fair and efficient sharing of channel resources among multiple vehicles for VANETs, which can provide timely packet transmissions and significantly improve road safety. In this paper, we review the standards of some countries for VANETs. Then, we divide the MAC protocols proposed for VANETs into single-channel MAC protocols and multi-channel MAC protocols according to the number of physical occupied spectrum resources. Both are further discussed based on their hierarchical structures, i.e., distributed and centralized structures. General design and optimization mechanisms of these commonly used MAC protocols for VANETs are reviewed. From the viewpoint of 7 aspects, we compare the advantages and disadvantages of these typical MAC protocols. Finally, we discuss the open issues to improve the MAC performance and future work on MAC design for VANETs.