[Components Characteristic and Source Apportionment of Fine Particulate Matter in Transition Period of Heating Season in Xi'an with High Time Resolution].

Influenced by heating, the concentration of atmospheric fine particulate matter (PM2.5) rises in autumn and winter in northern cities. In this study, Q-ACSM, AE33, and Xact 625 were used to carry out online monitoring of PM2.5 chemical components with high time resolution in Xi'an from October 25 to November 17, 2019, to analyze the characteristics of PM2.5 pollution during the transition period of the heating season. Additionally, we analyzed the sources of PM2.5 in combination with the positive matrix factorization model. The results showed that the average PM2.5 concentration during the observation period was (78.3 ± 38.5) µg·m-3, and the main chemical components were organic matter (OA), secondary inorganic ions (SIA), and dust, which accounted for 38.7%, 31.6%, and 21.2%, respectively. The average concentrations of sulfate, nitrate, and ammonium were (4.0 ± 3.1), (14.9 ± 13.7), and (5.8 ± 4.8) µg·m-3, and the average concentrations of the major metals potassium, calcium, and iron were (1.0 ± 0.4), (1.5 ± 1.1), and (1.4 ± 0.9) µg·m-3. Black carbon, chloride ions, and trace elements contributed relatively little to PM2.5 (5.7%, 1.3%, and 1.5%, respectively). In the pollution development and maintenance stage, the concentration of OA and SIA increased by 137.7% to 537.0%, whereas in the pollution dissipation stage, only the concentration of dust gradually increased. The source apportionment results showed that secondary sources, biomass burning, dust, vehicle emission, industrial emission, and coal combustion were the main sources of PM2.5 during the observation period, contributing 29.1%, 21.1%, 15.3%, 12.9%, 11.4%, and 10.2%, respectively. The contribution rate of secondary sources and biomass burning was higher in the pollution development and maintenance stage, and dust was higher in the pollution dissipation stage.

Optimization Design of MK-GGBS Based Geopolymer Repairing Mortar Based on Response Surface Methodology.

There are several influencing factors in the preparation of MK (metakaolin)-GGBS (ground granulated blast furnace slag)-based geopolymer repair mortars, including the MK-GGBS ratio, the alkalinity of the alkali activator solution, the modulus of the alkali activator solution, and the water-to-solid ratio. There are interactions between these factors, such as the different alkaline and modulus requirements of MK and GGBS, the interaction between the alkaline and modulus of the alkali activator solution, and the influence of water throughout the process. The effect of these interactions on the geopolymer repair mortar is not fully understood, making optimization of the MK-GGBS repair mortar ratio difficult. Therefore, in this paper, the response surface methodology (RSM) was used to optimize the preparation of the repair mortar, with GGBS content, SiO2/Na2O molar ratio, Na2O/binder ratio, and water/binder ratio as influencing factors and 1 d compressive strength, 1 d flexural strength, and 1 d bond strength as evaluation indices. Additionally, the repair mortar's overall performance was assessed in terms of setting time, long-term compressive and bond strength, shrinkage, water absorption, and efflorescence. The results show that RSM was successful in establishing a relationship between the repair mortar's properties and the factors. The recommended values of the GGBS content, Na2O/binder ratio, SiO2/Na2O molar ratio, and water/binder ratio are 60%, 10.1%, 1.19, and 0.41, respectively. The optimized mortar meets the standard's requirements for set time, water absorption, shrinkage values, and mechanical strength, with minimal visual efflorescence. The back-scattered electron (BSE) images and energy dispersive spectroscopy (EDS) analysis show that the geopolymer and cement have good interfacial adhesion, and a denser interfacial transition zone exists in the optimized proportion.

Distinct response properties between the FFA to faces and the PPA to houses.

INTRODUCTION: The object recognition system involves both selectivity to specific object category and invariance to changes in low-level visual features. Mounting neuroimaging evidence supports that brain areas in the ventral temporal cortex, such as the FFA and PPA, respond preferentially to faces and houses, respectively. However, how regions in human ventral temporal cortex partitioned and functionally organized to selectively and invariantly respond to different object categories remains unclear. What are the changes of response properties at the intersection of adjacent but distinctively-selective regions? METHOD: Here, we conducted an fMRI study and three-pronged analyses to compare the brain mapping relationships between the FFA to faces and the PPA to houses. Specifically, we examined: 1) the response properties of object selectivity to the preferred category; 2) the response properties of invariance to contrast and a concurrently presented non-preferred category; 3) whether there are asymmetrical changes of response properties across the boundary from the FFA to PPA versus from the PPA to FFA. RESULTS: We found that the response properties of FFA are highly selective and reliably invariant, whereas the responses of PPA vary with the image contrast and concurrently presented face. Moreover, the response properties across the boundary between the FFA and PPA are asymmetrical from face-selective to house-selective relative to from house-selective to face-selective. CONCLUSIONS: These results convergently revealed distinct response properties between the FFA to faces and the PPA to houses, implying a combination of spatially discrete domain-specific and relatively distributed domain-general organization mapping in human ventral temporal cortex.

Degradable microneedle patches loaded with antibacterial gelatin nanoparticles to treat staphylococcal infection-induced chronic wounds.

Infection-induced chronic wounds cause prolonged pains, a high risk of amputation, and even increased mortality in immunocompromised patients. Here we report an antibacterial microneedle (MN) patch, which features high degradability in biological fluids and gelatinase-responsive release of an antibacterial photothermal peptide AMP-Cypate. We first synthesize gelatin nanoparticles (GNPs) and then conjugate the AMP-Cypate to afford composite AMP-Cypate@GNPs. The proteinaceous nanoparticles can responsively release AMP-Cypate in the presence of gelatinase, an enzyme secreted specifically by Staphylococcus aureus (S. aureus). AMP-Cypate@GNPs were then deposited in the tips of MNs fabricated by PVP and recombinant human type III collagen (Col III) to devise the antibacterial MN/AMP-Cypate@GNP patches. When applied to the infection site, MNs break through the epidermis and the stratum corneum, dissolve in the infected dermis, reach the bacterial colony or biofilm, release AMP-Cypate@GNPs, and exert a gelatinase-responsive photothermal therapy under near-infrared (NIR) irradiation to kill the pathogen S. aureus. In a rat model of staphylococcal infection-induced chronic wounds mimicking the condition of diabetic foot ulcer, the antibacterial MN/AMP-Cypate@GNP patches eradiated the bacterial infection and resulted in complete healing of the wounds, proving its potential application in the treatment of chronic wound infections and diabetic foot ulcers.

Antimicrobial Peptide-Loaded Gelatinase-Responsive Photothermal Nanogel for the Treatment of Staphylococcus aureus-Infected Wounds.

As the most common pathogen of community and nosocomial infection, the resistance of Staphylococcus aureus (S. aureus) to traditional antibiotics is still increasing with years. Although the potent antibacterial activity of antimicrobial peptides (AMPs) has been widely confirmed, the unpredictable cytotoxicity remains the biggest obstacle to their clinical application. The development of a targeted drug delivery system for S. aureus is a practical strategy to ameliorate the inherent limitations of AMPs. In this work, we constructed an AMP release nanogel (cypate-GNPs@Cy3-AMP, CGCA) of S. aureus infection microenvironment using gelatinase nanoparticles (GNPs) for toxicity control and bacterial clearance. Gelatinase present in the infected site degrades GNPs, thus releasing Cy3-AMP in situ to destroy bacterial cells. Cypate modified on the surface of GNPs supports CGCA to generate localized heat under near-infrared (NIR) laser irradiation, which together with AMPs could cause irreversible physical damage to bacteria. In addition, the encapsulation from GNPs not only effectively limited the toxicity of AMPs but also significantly promoted cell proliferation and migration in vitro. In the mouse infection model, CGCA also exhibited excellent effects of bacterial clearance and wound healing, providing a potential direction for the correct use of AMPs.

Anchorage independence altered vasculogenic phenotype of melanoma cells through downregulation in aminopeptidase N /syndecan-1/integrin ß4 axis.

The detachment of tumor cells from extracellular matrix and survival under anchorage-independence were recognized as the initial step of tumor metastasis. Previously we had demonstrated that anchorage-independence altered gene expressions and showed characteristics of cell invasiveness loss, enhanced chemosensitivity, and enhanced subcutaneous tumor formation. However, whether it affected histological phenotypes in tumor tissues remained unclear. Melanoma metastases were generated in nude mice using adherent or suspended melanoma cells. Examination of melanoma metastases revealed histological features of extensive vascular structures in adherent cell-derived tumors, while not seen in suspended cell-derived tumors. Quantitative proteomic analysis at adherent, suspended, and re-attached melanoma cells suggested that aminopeptidase N was potentially downregulated upon cell suspension or reattachment. Downregulation of aminopeptidase N by gene-specific shRNAs showed reduced cell invasiveness and enhanced subcutaneous tumor formation that was consistent with previous observations. Experiments by suppression or overexpression of aminopeptidase N expression demonstrated that aminopeptidase N regulated syndecan-1 and integrin ß4 expression through PKCδ pathway. Histological analysis at melanoma metastases further suggested that CD31+/aminopeptidase N+/syndecan-1+/integrin ß4+ phenotypes were associated with vascular structures. In summary, we suggested the expression axis of aminopeptidase N/syndecan-1/integrin ß4 in melanoma cells was suppressed by detachment stress, which diminished vascular phenotypes of melanoma metastases.

The Neural Mechanism of Number Line Bisection: A fMRI study.

The neural networks involved in number line bisection are poorly understood. We used functional magnetic resonance imaging (fMRI) to investigate these. fMRI was analyzed from 28 healthy volunteers who performed number and physical line bisection tasks (and their respective baselines). Whole brain analyses showed that these two bisection tasks shared common neural correlates in bilateral parietal-frontal networks; furthermore, bilateral parietal-frontal areas, right cerebellum, left insula and supplementary motor area (SMA) showed higher activity when contrasting the number line with a physical line bisection task. Importantly, psychophysiological interaction (PPI) analyses further indicated that left SMA and right cerebellum were connected to parietal-frontal areas for implementing the number line bisection task. Our findings suggested that a visuospatial attention control system was recruited, and mental imagery of a number line was used to find the midpoint of a numerical interval without calculations.

Addition and Subtraction but Not Multiplication and Division Cause Shifts of Spatial Attention.

Many studies have shown that solving addition and subtraction problems can induce overt shifts of spatial attention. In particular, right-side targets are detected faster than left-side targets when preceded by an addition operation, while left-side targets are detected faster than right-side targets when preceded by a subtraction operation. However, the interaction between space and arithmetic in multiplication or division is hardly studied and remains controversial. In order to make a strong case for the interaction between space and mental arithmetic, we attempted to replicate the spatial-arithmetic association in addition and subtraction (Experiment 1), and at the same time investigated whether shift of spatial attention would also be induced by multiplication or division operations (Experiment 2). We found that solving addition problems facilitated the detection of right-side targets, whereas left-side targets were detected faster after solving subtraction problems. However, no interaction between space and arithmetic operation was observed in multiplication or division. The implication of these findings is discussed.

Dissociated Spatial-Arithmetic Associations in Horizontal and Vertical Dimensions.

Spatial-numerical associations (small numbers-left/lower space and large numbers-right/upper space) are regularly found in elementary number processing. Recently, the interest in this phenomenon has been extended from elementary number processing to mental arithmetic. Many studies have demonstrated horizontal spatial-arithmetic associations, i.e., solving addition or subtraction problems cause spatial shifts of attention rightward or leftward, respectively. However, the role of this effect in the vertical dimension has not been addressed. This is problematic because it leaves the analogy between elementary number processing and arithmetic incomplete. In order to make a strong case for a similarity between elementary number processing and mental arithmetic, a spatial-arithmetic association should be observed in the vertical dimension too. Here, we adopted the target detection paradigm from Liu et al. (2017) to replicate the horizontal spatial-arithmetic association, and meanwhile investigate whether this effect also exists in the vertical direction. Our results confirmed that addition could induce covert movement to right side and subtraction to left side. However, such a spatial-arithmetic association was not found in the vertical dimension. The implication of these findings is discussed.