Associations between perceived and actual risk of HIV infection and HIV prevention services uptake among men who have sex with men in Shandong province, China: a cross-sectional study.

BACKGROUND: Associations between perceived and actual risk of HIV infection and HIV prevention services uptake are inconclusive. This study aimed to evaluate the discrepancy between the perceived and actual HIV risk, and quantify the associations between perceived and actual risk of HIV infection and three HIV prevention services utilization among men who have sex with men (MSM) in Shandong province, China. METHODS: A cross-sectional study was conducted in Shandong province in June 2021. Participants were eligible if they were born biologically male, aged 18 years or older, had negative or unknown HIV status, and had sex with men in the past year. Participants were recruited online. The discrepancy between their perceived and actual risk of HIV infection was evaluated by calculating the Kappa value. Bayesian model averaging was used to assess the associations between perceived and actual risk of HIV infection and HIV prevention services uptake. RESULTS: A total of 1136 MSM were recruited, most of them were 30 years old or younger (59.9%), single (79.5%), with at least college education level (74.7%). Most participants (97.4%) perceived that they had low risk of HIV infection, and 14.1% were assessed with high actual risk. The discrepancy between their perceived and actual risk of HIV infection was evaluated with a Kappa value of 0.076 (P < 0.001). HIV testing uptake had a weak association with perceived high HIV prevalence among social networks (aOR = 1.156, post probability = 0.547). The perceived high HIV prevalence among national MSM was positive related to willingness to use PrEP (aOR = 1.903, post probability = 0.943) and PEP (aOR = 1.737, post probability = 0.829). Perceived personal risk (aOR = 4.486, post probability = 0.994) and perceived HIV prevalence among social networks (aOR = 1.280, post probability = 0.572) were related to history of using PrEP. Perceived personal risk (aOR = 3.144, post probability = 0.952), actual risk (aOR = 1.890, post probability = 0.950), and perceived risk among social networks (aOR = 1.502, post probability = 0.786) were related to history of using PEP. CONCLUSIONS: There is discordance between perceived and actual personal risk of HIV infection among MSM in China. HIV risk assessment and education on HIV prevalence among MSM should be strengthened to assist high-risk populations aware their risk accurately and hence access HIV prevention services proactively.

Alcohol consumption and utilization of HIV prevention services among men who have casual sex with women in China.

Men who have casual sex with women (MCSW) have played an important role in HIV new infections in China. Research studies have shown that heavy alcohol consumption can increase the risk of HIV infection. The cross-sectional study was conducted in two cities in China from December 2018 to May 2019 to examine the association between alcohol consumption and utilization of HIV prevention services among MCSW. Convenience sampling was used to recruit participants and 400 MCSW were recruited in this study. There were 238 (59.6%), 213 (53.4%) and 129 (32.4%) participants having utilized HIV prevention services, condom promotion and distribution or HIV counseling and testing (CPD/HCT) services, and peer education services in the past 12 months, respectively. MCSW who were identified as heavy drinkers were less likely to utilize HIV prevention services and CPD/HCT services compared with non-drinkers. For youngsters, those who are in the local household and those who are married/cohabitating, heavy drinkers was less likely to utilize HIV prevention services. This study highlights the significance of intensive education on heavy drinkers of MCSW, particularly for high-risk subgroups. Targeting resources for integrated HIV prevention efforts with alcohol-using MCSW should be considered by public health policymakers.

Digital, Crowdsourced, Multilevel Intervention to Promote HIV Testing Among Men Who Have Sex With Men: Cluster Randomized Controlled Trial.

BACKGROUND: Despite great efforts in HIV prevention worldwide, HIV testing uptake among men who have sex with men (MSM) remains suboptimal. The effectiveness of digital, crowdsourced, multilevel interventions in improving HIV testing is still unclear. OBJECTIVE: The aim of this study was to evaluate the effect of a digital, crowdsourced, multilevel intervention in improving HIV testing uptake among MSM in China. METHODS: We conducted a 2-arm cluster randomized controlled trial among MSM in 11 cities in Shandong province, China, from August 2019 to April 2020. Participants were men who were HIV seronegative or had unknown serum status, had anal sex with a man in the past 12 months, and had not been tested for HIV in the past 3 months. Participants were recruited through a gay dating app and community-based organizations from preselected cities; these cities were matched into 5 blocks (2 clusters per block) and further randomly assigned (1:1) to receive a digital, crowdsourced, multilevel intervention (intervention arm) or routine intervention (control arm). The digital multilevel intervention was developed through crowdsourced open calls tailored for MSM, consisting of digital intervention images and videos, the strategy of providing HIV self-testing services through digital tools, and peer-moderated discussion within WeChat groups. The primary outcome was self-reported HIV testing uptake in the previous 3 months. An intention-to-treat approach was used to examine the cluster-level effect of the intervention in the 12-month study period using generalized linear mixed models and the individual-level effect using linear mixed models. RESULTS: A total of 935 MSM were enrolled (404 intervention participants and 531 controls); 751 participants (80.3%) completed at least one follow-up survey. Most participants were younger than 30 years (n=601, 64.3%), single (n=681, 72.8%), had a college degree or higher (n=629, 67.3%), and had an HIV testing history (n=785, 84%). Overall, the proportion of testing for HIV in the past 3 months at the 3-, 6-, 9-, and 12-month follow-ups was higher in the intervention arm (139/279, 49.8%; 148/266, 55.6%; 189/263, 71.9%; and 171/266, 64.3%, respectively) than the control arm (183/418, 43.8%; 178/408, 43.6%; 206/403, 51.1%; and 182/397, 48.4%, respectively), with statistically significant differences at the 6-, 9-, and 12-month follow-ups. At the cluster level, the proportion of participants who had tested for HIV increased 11.62% (95% CI 0.74%-22.5%; P=.04) with the intervention. At the individual level, participants in the intervention arm had 69% higher odds for testing for HIV in the past 3 months compared with control participants, but the result was not statistically significant (risk ratio 1.69, 95% CI 0.87-3.27; P=.11). CONCLUSIONS: The intervention effectively improved HIV testing uptake among Chinese MSM. Our findings highlight that digital, crowdsourced, multilevel interventions should be made more widely available for HIV prevention and other public health issues. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR1900024350; http://www.chictr.org.cn/showproj.aspx?proj=36718. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1186/s13063-020-04860-8.

High Sensitivity Temperature Sensing of Long-Period Fiber Grating for the Ocean.

In this study, a new temperature sensor with high sensitivity was achieved by four-layer Ge and B co-doped long-period fiber grating (LPFG) based on the mode coupling principle. By analyzing the mode conversion, the influence of the surrounding refractive index (SRI), the thickness and the refractive index of the film on the sensitivity of the sensor is studied. When 10 nm-thick titanium dioxide (TiO2) film is coated on the surface of the bare LPFG, the refractive index sensitivity of the sensor can be initially improved. Packaging PC452 UV-curable adhesive with a high-thermoluminescence coefficient for temperature sensitization can realize high-sensitivity temperature sensing and meet the requirements of ocean temperature detection. Finally, the effects of salt and protein attachment on the sensitivity are analyzed, which provides a reference for the subsequent application. The sensitivity of 3.8 nm/°C in the range of 5-30 °C was achieved for this new sensor, and the resolution is about 0.00026 °C, which is over 20 times higher than ordinary temperature sensors. This new sensor meets the accuracy and range of general ocean temperature measurements and could be used in various marine monitoring and environmental protection applications.

Effect of Hydrophobicity and Charge Separation on the Antifouling Properties of Surface-Tethered Zwitterionic Peptides.

Zwitterionic peptides emerge as a class of highly effective antifouling material in a wide range of applications such as biosensors, biomedical devices, and implants. We incorporated neutral amino acid spacers with different hydrophobicities, including serine (Ser), glycine (Gly), and leucine (Leu), into zwitterionic peptides with lysine-glutamic acid repeating units and investigated the structure and antifouling performance of the zwitterionic peptide brushes by surface plasma resonance, surface force apparatus (SFA), and all-atomistic molecular dynamics (MD) simulation techniques. Our results demonstrate that the hydrophilicity of neutral spacers alters the structure and antifouling performance of the peptide-modified surface. Hydrophilic Ser-inserted peptides reduced the interaction between the peptide monolayer and protein foulants, while hydrophobic Leu significantly increased the protein adhesion. SFA force measurements show that the presence of more spacers would increase the adhesion between the peptide monolayer and the modeling foulant lysozyme, especially for the hydrophobic spacers. MD simulations reveal that hydrophilic Ser spacers retain the hydrophilicity of the peptide monolayer and improve the antifouling performance, and Gly spacers give rise to more interchain cross-links. Leu spacers result in a more hydrophobic peptide monolayer, which leads to dehydration of the peptide monolayer and reduces the antifouling performances.

The mediated effect of HIV risk perception in the relationship between peer education and HIV testing uptake among three key populations in China.

BACKGROUND: Peer education and HIV risk perception are related to HIV testing uptake among key populations. We aimed to examine the association between peer education, HIV risk perception, and HIV testing uptake, as well as to evaluate the mediated effect of HIV risk perception in the relationship between peer education and HIV testing uptake. METHODS: We conducted a cross-sectional survey among 1188 HIV-uninfected or unknown participants from populations of men who have sex with men (MSM), female sex workers (FSWs), and drug users (DUs) in seven cities of China. Partial correlation analysis and regression analysis were employed to examine the associations among peer education, HIV risk perception, and HIV testing uptake. Mediation analysis was conducted to assess whether HIV risk perception mediated the hypothesized association. RESULTS: Receiving peer education was associated with higher odds of HIV testing uptake among MSM, FSWs and DUs. Perceiving risk of HIV infection was associated with higher odds of HIV testing uptake among MSM and DUs. Among MSM, the relationship between peer education and HIV testing uptake was mediated by moderate risk perception of HIV (indirect effect: 0.53, 95% CI 0.07 to 1.21), and by high risk perception of HIV (indirect effect: 0.50, 95% CI 0.01 to 1.17). Among DUs, the relationship between peer education and HIV testing uptake was mediated by moderate risk perception of HIV (indirect effect: 1.80, 95% CI 0.57 to 3.45). CONCLUSIONS: Participants who received peer education tended to perceive their risk of HIV infection, which in turn was associated with increased HIV testing uptake among MSM and DUs. Therefore, in addition to peer education interventions, more report about HIV epidemic and risk assessment should also be scaled up to enhance HIV risk perception among key populations.

Synergistic effect of polystyrene nanoplastics and contaminants on the promotion of insulin fibrillation.

Nanoplastics (NPs) are becoming an emerging pollutant of global concern. A potential risk of NPs is that they can serve as carriers and synergistically function with other contaminants to cause diseases. A variety of diseases such as Alzheimer's disease are related to the generation of amyloid fibrils, and insulin is typically used as a model to study the fibrillation process. In this study, we examined the fibrillation of insulin promoted by polystyrene nanoplastics (PSNPs) alone and synergistically with organic contaminants (denoted as X, X = pyrene, bisphenol A, 2,2',4,4'-tetrabromodiphenyl ether, 4,4'-dihydroxydiphenylmethane, or 4-nonylphenol) having different polarities using thioflavin T fluorescence assays, dynamic light scattering, and circular dichroism spectroscopy. The presence of PSNPs and small organic contaminants decreased the lag phase time (tlag) for insulin fibrillation from 54.6 h to 35-51 h and their combination (PS-X) enhanced this process (tlag = 21-30 h). Notably, the lag phase time for insulin fibrillation with PS-nonpolar contaminants, PS-weakly polar contaminants, and PS-polar contaminants is around 20.8, 26.7, and 30.1 h, respectively, indicating the synergistic effect of PS-nonpolar contaminants or PS-weakly polar contaminants was more obvious than that of PS-polar contaminants. Moreover, molecular dynamic simulation reveal the interactions between insulin and PSs or small organic contaminants are primarily driven by van der Waals forces and hydrophobic interactions. Overall, the findings of this study underscore the potentially significant environmental impact of small organic contaminants assisting NPs in promoting insulin fibrillation.

Structures and Antifouling Properties of Self-Assembled Zwitterionic Peptide Monolayers: Effects of Peptide Charge Distributions and Divalent Cations.

Zwitterionic peptides are great candidates as antifouling coating materials in many biomedical applications. We investigated the structure and antifouling properties of surface-tethered zwitterionic peptide monolayers with different peptide chain lengths and charge distributions using a combination of surface plasma resonance, atomic force microscopy, and all atomistic molecular dynamics (MD) simulation techniques. Our results demonstrate that zwitterionic peptides with more zwitterionic lysine (K) and glutamic acid (E) repeating units exhibit better antifouling performance. The block charge distributions of the positive and negative charges in the peptides (having multiple positive charges next to the same amount of negative charges), although affecting the structure of the peptide molecules, do not significantly change the antifouling properties of the peptide monolayers in the solutions containing monovalent ions. However, divalent cations, Ca2+ and Mg2+, in solution can significantly alter the structure and lower the antifouling performance of the zwitterionic peptide monolayers, especially with the sequences of block charges. All atomistic MD simulations quantitatively reveal that the divalent cations in solution lead to more interchain electrostatic cross-links between peptide chains, especially for peptides with block charges, which causes dehydration of the zwitterionic peptides and diminishes their antifouling performances.

Image Processing of Porous Silicon Microarray in Refractive Index Change Detection.

A new method for extracting the dots is proposed by the reflected light image of porous silicon (PSi) microarray utilization in this paper. The method consists of three parts: pretreatment, tilt correction and spot segmentation. First, based on the characteristics of different components in HSV (Hue, Saturation, Value) space, a special pretreatment is proposed for the reflected light image to obtain the contour edges of the array cells in the image. Second, through the geometric relationship of the target object between the initial external rectangle and the minimum bounding rectangle (MBR), a new tilt correction algorithm based on the MBR is proposed to adjust the image. Third, based on the specific requirements of the reflected light image segmentation, the array cells are segmented into dots as large as possible and the distance between the dots is equal in the corrected image. Experimental results show that the pretreatment part of this method can effectively avoid the influence of complex background and complete the binarization processing of the image. The tilt correction algorithm has a shorter computation time, which makes it highly suitable for tilt correction of reflected light images. The segmentation algorithm makes the dots in a regular arrangement, excludes the edges and the bright spots. This method could be utilized in the fast, accurate and automatic dots extraction of the PSi microarray reflected light image.

Parallel Detection of Refractive Index Changes in a Porous Silicon Microarray Based on Digital Images.

A new technique for the refractive index change with high-sensitivity measurements was proposed by the digital image of porous silicon (PSi) microarray utilization in this paper. Under the irradiation of a He-Ne laser, the surface images of the PSi array cells with the microcavity structure were obtained by the digital imaging equipment, whereas the refractive index change of each array cells was detected by calculating the average gray value of the image and the refractive index change measurement sensitivity was 10-4. This technique could be utilized in the label-free and parallel detection of refraction index changes induced by a biological reaction in the microarray or the chip.

Data-driven prediction on critical mechanical properties of engineered cementitious composites based on machine learning.

The present study introduces a novel approach utilizing machine learning techniques to predict the crucial mechanical properties of engineered cementitious composites (ECCs), spanning from typical to exceptionally high strength levels. These properties, including compressive strength, flexural strength, tensile strength, and tensile strain capacity, can not only be predicted but also precisely estimated. The investigation encompassed a meticulous compilation and examination of 1532 datasets sourced from pertinent research. Four machine learning algorithms, linear regression (LR), K nearest neighbors (KNN), random forest (RF), and extreme gradient boosting (XGB), were used to establish the prediction model of ECC mechanical properties and determine the optimal model. The optimal model was utilized to employ SHapley Additive exPlanations (SHAP) for scrutinizing feature importance and conducting an in-depth parametric analysis. Subsequently, a comprehensive control strategy was devised for ECC mechanical properties. This strategy can provide actionable guidance for ECC design, equipping engineers and professionals in civil engineering and material science to make informed decisions throughout their design endeavors. The results show that the RF model demonstrated the highest prediction accuracy for compressive strength and flexural strength, with R2 values of 0.92 and 0.91 on the test set. The XGB model outperformed in predicting tensile strength and tensile strain capacity, with R2 values of 0.87 and 0.80 on the test set, respectively. The prediction of tensile strain capacity was the least accurate. Meanwhile, the MAE of the tensile strain capacity was a mere 0.84%, smaller than the variability (1.77%) of the test results in previous research. Compressive strength and tensile strength demonstrated high sensitivity to variations in both water-cement ratio (W) and water reducer (WR). In contrast, flexural strength exhibited high sensitivity solely to changes in W. Conversely, the sensitivity of tensile strain capacity to input features was moderate and consistent. The mechanical attributes of ECC emerged from the combined effects of multiple positive and negative features. Notably, WR exerted the most significant influence on compressive strength among all features, whereas polyethylene (PE) fiber emerged as the primary driver affecting flexural strength, tensile strength, and tensile strain capacity.

The patterns and driving forces of dengue invasions in China.

BACKGROUND: Global connectivity and environmental change pose continuous threats to dengue invasions from worldwide to China. However, the intrinsic relationship on introduction and outbreak risks of dengue driven by the landscape features are still unknown. This study aimed to map the patterns on source-sink relation of dengue cases and assess the driving forces for dengue invasions in China. METHODS: We identified the local and imported cases (2006-2020) and assembled the datasets on environmental conditions. The vector auto-regression model was applied to detect the cross-relations of source-sink patterns. We selected the major environmental drivers via the Boruta algorithm to assess the driving forces in dengue outbreak dynamics by applying generalized additive models. We reconstructed the internal connections among imported cases, local cases, and external environmental drivers using the structural equation modeling. RESULTS: From 2006 to 2020, 81,652 local dengue cases and 12,701 imported dengue cases in China were reported. The hotspots of dengue introductions and outbreaks were in southeast and southwest China, originating from South and Southeast Asia. Oversea-imported dengue cases, as the Granger-cause, were the initial driver of the dengue dynamic; the suitable local bio-socioecological environment is the fundamental factor for dengue epidemics. The Bio8 [odds ratio (OR) = 2.11, 95% confidence interval (CI): 1.67-2.68], Bio9 (OR = 291.62, 95% CI: 125.63-676.89), Bio15 (OR = 4.15, 95% CI: 3.30-5.24), normalized difference vegetation index in March (OR = 1.27, 95% CI: 1.06-1.51) and July (OR = 1.04, 95% CI: 1.00-1.07), and the imported cases are the major drivers of dengue local transmissions (OR = 4.79, 95% CI: 4.34-5.28). The intermediary effect of an index on population and economic development to local cases via the path of imported cases was detected in the dengue dynamic system. CONCLUSIONS: Dengue outbreaks in China are triggered by introductions of imported cases and boosted by landscape features and connectivity. Our research will contribute to developing nature-based solutions for dengue surveillance, mitigation, and control from a socio-ecological perspective based on invasion ecology theories to control and prevent future dengue invasion and localization.

Effect of Polyoxymethylene Fiber on the Mechanical Properties and Abrasion Resistance of Ultra-High-Performance Concrete.

It is necessary to prepare marine UHPC with synthetic fibers instead of steel fibers, owing to the corrosion risk of steel fibers in marine environments. Currently, the performance of UHPC prepared with different types of fibers has not been comparatively investigated. This work prepared UHPC with steel fiber, polyoxymethylene (POM) fiber, polypropylene (PP) fiber, and polyvinyl alcohol (PVA) fiber. The effects of different fibers on the mechanical properties, impact, and abrasion resistance of UHPC were studied and compared. The results showed that increasing POM fiber can increase the mechanical strength, flexural toughness, impact, and abrasion resistance of UHPC. When its content reaches 2%, the adsorbed-in-fracture energy and abrasion strength of UHPC are 2670 J and 105 h/(kg/m2), respectively. At the same fiber content, POM fiber-reinforced UHPC shows better mechanical strength, toughness, and impact- and abrasion-resistance than the polypropylene (PP)- and polyvinyl alcohol (PVA)-fiber-reinforced UHPCs. Microstructure investigation found that PP fiber has the weakest binding with UHPC paste, which would directly pull out of the matrix under external tensile loading. This weak connection limits the strengthening and toughening effect on the UHPC. PVA fiber has an excellent interfacial connection with the UHPC paste. However, the low tensile strength of PVA fiber limits the strength and toughness of UHPC. POM fiber has a high tensile strength and can absorb tensile loading through debonding, fracture, and tearing. The fracture interface of POM fiber is large, indicating its significant role in strengthening and toughening the UHPC.

Association Between Hydrological Conditions and Dengue Fever Incidence in Coastal Southeastern China From 2013 to 2019.

Importance: Dengue fever is a climate-sensitive infectious disease. However, its association with local hydrological conditions and the role of city development remain unclear. Objective: To quantify the association between hydrological conditions and dengue fever incidence in China and to explore the modification role of city development in this association. Design, Setting, and Participants: This cross-sectional study collected data between January 1, 2013, and December 31, 2019, from 54 cities in 4 coastal provinces in southeast China. The Standardized Precipitation Evapotranspiration Index (SPEI) was calculated from ambient temperature and precipitation, with SPEI thresholds of 2 for extreme wet conditions and -2 for extreme dry conditions. The SPEI-dengue fever incidence association was examined over a 6-month lag, and the modification roles of 5 city development dimensions were assessed. Data were analyzed in May 2022. Exposures: City-level monthly temperature, precipitation, SPEI, and annual city development indicators from 2013 to 2019. Main Outcomes and Measures: The primary outcome was city-level monthly dengue fever incidence. Spatiotemporal bayesian hierarchal models were used to examine the SPEI-dengue fever incidence association over a 6-month lag period. An interaction term between SPEI and each city development indicator was added into the model to assess the modification role of city development. Results: Included in the analysis were 70 006 dengue fever cases reported in 54 cities in 4 provinces in China from 2013 to 2019. Overall, a U-shaped cumulative curve was observed, with wet and dry conditions both associated with increased dengue fever risk. The relative risk [RR] peaked at a 1-month lag for extreme wet conditions (1.27; 95% credible interval [CrI], 1.05-1.53) and at a 6-month lag for extreme dry conditions (1.63; 95% CrI, 1.29-2.05). The RRs of extreme wet and dry conditions were greater in areas with limited economic development, health care resources, and income per capita. Extreme dry conditions were higher and prolonged in areas with more green space per capita (RR, 1.84; 95% CrI, 1.37-2.46). Highly urbanized areas had a higher risk of dengue fever after extreme wet conditions (RR, 1.80; 95% CrI, 1.26-2.56), while less urbanized areas had the highest risk of dengue fever in extreme dry conditions (RR, 1.70; 95% CrI, 1.11-2.60). Conclusions and Relevance: Results of this study showed that extreme hydrological conditions were associated with increased dengue fever incidence within a 6-month lag period, with different dimensions of city development playing various modification roles in this association. These findings may help in developing climate change adaptation strategies and public health interventions against dengue fever.

Projecting future risk of dengue related to hydrometeorological conditions in mainland China under climate change scenarios: a modelling study.

BACKGROUND: We have limited knowledge on the impact of hydrometeorological conditions on dengue incidence in China and its associated disease burden in a future with a changed climate. This study projects the excess risk of dengue caused by climate change-induced hydrometeorological conditions across mainland China. METHODS: In this modelling study, the historical association between the Palmer drought severity index (PDSI) and dengue was estimated with a spatiotemporal Bayesian hierarchical model from 70 cities. The association combined with the dengue-transmission biological model was used to project the annual excess risk of dengue related to PDSI by 2100 across mainland China, under three representative concentration pathways ([RCP] 2·6, RCP 4·5, and RCP 8·5). FINDINGS: 93 101 dengue cases were reported between 2013 and 2019 in mainland China. Dry and wet conditions within 3 months lag were associated with increased risk of dengue. Locations with potential dengue risk in China will expand in the future. The hydrometeorological changes are projected to substantially affect the risk of dengue in regions with mid-to-low latitudes, especially the coastal areas under high emission scenarios. By 2100, the annual average increased excess risk is expected to range from 12·56% (95% empirical CI 9·54-22·24) in northwest China to 173·62% (153·15-254·82) in south China under the highest emission scenario. INTERPRETATION: Hydrometeorological conditions are predicted to increase the risk of dengue in the future in the south, east, and central areas of mainland China in disproportionate patterns. Our findings have implications for the preparation of public health interventions to minimise the health hazards of non-optimal hydrometeorological conditions in a context of climate change. FUNDING: National Natural Science Foundation of China.

Enhancement of Mechanical and Bond Properties of Epoxy Adhesives Modified by SiO2 Nanoparticles with Active Groups.

In order to improve the mechanical and bond properties of epoxy adhesives for their wide scope of applications, modified epoxy adhesives were produced in this study with SiO2 nanoparticles of 20 nm in size, including inactive groups, NH2 active groups, and C4H8 active groups. The mechanical properties of specimens were examined, and an investigation was conducted into the effects of epoxy adhesive modified by three kinds of SiO2 nanoparticles on the bond properties of carbon fiber reinforced polymer and steel (CFRP/steel) double lap joints. According to scanning electron microscopy (SEM), the distribution effect in epoxy adhesive of SiO2 nanoparticles modified by active groups was better than that of inactive groups. When the mass fraction of SiO2-C4H8 nanoparticles was 0.05%, the tensile strength, tensile modulus, elongation at break, bending strength, flexural modulus, and impact strength of the epoxy adhesives reached their maximum, which were 47.63%, 44.81%, 57.31%, 62.17%, 33.72%, 78.89%, and 68.86% higher than that of the EP, respectively, and 8.45%, 9.52%, 9.24%, 20.22%, 17.76%, 20.18%, and 12.65% higher than that of the inactive groups of SiO2 nanoparticles, respectively. The SiO2 nanoparticles modified with NH2 or C4H8 active groups were effective in improving the ultimate load-bearing capacity and bond properties of epoxy adhesives glued to CFRP/steel double lap joints, thus increasing the strain and interface shear stress peak value of the CFRP surface.

Short-term effects of tropical cyclones on the incidence of dengue: a time-series study in Guangzhou, China.

BACKGROUND: Limited evidence is available about the association between tropical cyclones and dengue incidence. This study aimed to examine the effects of tropical cyclones on the incidence of dengue and to explore the vulnerable populations in Guangzhou, China. METHODS: Weekly dengue case data, tropical cyclone and meteorological data during the tropical cyclones season (June to October) from 2015 to 2019 were collected for the study. A quasi-Poisson generalized linear model combined with a distributed lag non-linear model was conducted to quantify the association between tropical cyclones and dengue, controlling for meteorological factors, seasonality, and long-term trend. Proportion of dengue cases attributable to tropical cyclone exposure was calculated. The effect difference by sex and age groups was calculated to identify vulnerable populations. The tropical cyclones were classified into two levels to compare the effects of different grades of tropical cyclones on the dengue incidence. RESULTS: Tropical cyclones were associated with an increased number of dengue cases with the maximum risk ratio of 1.41 (95% confidence interval 1.17-1.69) in lag 0 week and cumulative risk ratio of 2.13 (95% confidence interval 1.28-3.56) in lag 0-4 weeks. The attributable fraction was 6.31% (95% empirical confidence interval 1.96-10.16%). Men and the elderly were more vulnerable to the effects of tropical cyclones than the others. The effects of typhoons were stronger than those of tropical storms among various subpopulations. CONCLUSIONS: Our findings indicate that tropical cyclones may increase the incidence of dengue within a 4-week lag in Guangzhou, China, and the effects were more pronounced in men and the elderly. Precautionary measures should be taken with a focus on the identified vulnerable populations to control the transmission of dengue associated with tropical cyclones.

OCT based four-dimensional cardiac imaging of a living chick embryo using an impedance signal as a gating for post-acquisition synchronization.

Optical coherence tomography (OCT) is a non-invasive imaging modality with high spatial resolution suitable for early embryonic heart imaging. However, the most commonly used OCT systems cannot provide direct 4-D imaging due to acquisition speed limitations. We proposed a retrospective gating 4-D reconstruction method based on spectral domain OCT. A special circuit was designed to measure the impedance change of chick embryos in response to the heart beating. The impedance signal was acquired simultaneously with the OCT B-scan image sequence at several different locations along the heart. The impedance signal was used as a gating for 4-D reconstruction. The reconstruction algorithm includes cardiac period calculation, interpolation from multi-cardiac cycle image sequence into one cardiac cycle, and cardiac phase synchronization among the different locations of the heart. The synchronism of the impedance signal change with the heartbeat was verified. Using the proposed method, we reconstructed the cardiac outflow tract (OFT) of chick embryos at an early stage of development (Hamburger-Hamilton stage 18). We showed that the reconstructed 4-D images correctly captured the dynamics of the OFT wall motion.

The association between tropical cyclones and dengue fever in the Pearl River Delta, China during 2013-2018: A time-stratified case-crossover study.

BACKGROUND: Studies have shown that tropical cyclones are associated with several infectious diseases, while very few evidence has demonstrated the relationship between tropical cyclones and dengue fever. This study aimed to examine the potential impact of tropical cyclones on dengue fever incidence in the Pearl River Delta, China. METHODS: Data on daily dengue fever incidence, occurrence of tropical cyclones and meteorological factors were collected between June and October, 2013-2018 from nine cities in the Pearl River Delta. Multicollinearity of meteorological variables was examined via Spearman correlation, variables with strong correlation (r>0.7) were not included in the model simultaneously. A time-stratified case-crossover design combined with conditional Poisson regression model was performed to evaluate the association between tropical cyclones and dengue fever incidence. Stratified analyses were performed by intensity grades of tropical cyclones (tropical storm and typhoon), sex (male and female) and age-groups (<18, 18-59, ≥60 years). RESULTS: During the study period, 20 tropical cyclones occurred and 47,784 dengue fever cases were reported. Tropical cyclones were associated with an increased risk of dengue fever in the Pearl River Delta region, with the largest relative risk of 1.62 with the 95% confidence interval (1.45-1.80) occurring on the lag 5 day. The strength of association was greater and lasted longer for typhoon than for tropical storm. There was no difference in effect estimates between males and females. However, individuals aged over 60 years were more vulnerable than others. CONCLUSIONS: Tropical cyclones are associated with increased risk of local dengue fever incidence in south China, with the elderly more vulnerable than other population subgroups. Health protective strategies should be developed to reduce the potential risk of dengue epidemic after tropical cyclones.

Solidification of municipal solid waste incineration fly ash and immobilization of heavy metals using waste glass in alkaline activation system.

Hazardous heavy metals in Municipal Solid Waste Incineration (MSWI) fly ash are a threat to the environment and ecosystems. The objective of the work is to investigate the solidification of MSWI fly ash and the immobilization of the heavy metals through alkaline activation reaction with waste glass as an additive. Compressive strength measurement, X-ray diffraction (XRD), 29Si nuclear magnetic resonance spectroscopy (29Si NMR) and scanning electron microscope (SEM) were performed to evaluate the solidification effect and characterize the microstructure of alkali-activated MSWI fly ash-based mortars. The leaching test, back-scattered electron microscopy (BSE) and X-ray photoelectron spectroscopy (XPS) were conducted to determine the heavy metals' immobilization effect and their immobilization forms. It was found that waste glass addition effectively reinforced the solidification of MSWI fly ash and immobilized the heavy metals. With 40% addition of waste glass, the compressive strength reached a maximum of 3.55 MPa. The immobilization efficiency of Cr increased with the addition of waste glass, while that of Cu, Pb, Zn and Cd is dependent on the eluant final pH, which decreased with the decrease of eluant final pH. The main immobilization forms include physical encapsulation, the formation of alkaline environment and the generation of silicate compounds.