Southern University of Science and Technology
Recent publications
Growing studies have linked metal exposure to diabetes risk. However, these studies had inconsistent results. We used a multiple linear regression model to investigate the sex-specific and dose-response associations between urinary metals (cobalt (Co) and molybdenum (Mo)) and diabetes-related indicators (fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), homeostasis model assessment for insulin resistance (HOMA-IR), and insulin) in a cross-sectional study based on the United States National Health and Nutrition Examination Survey. The urinary metal concentrations of 1423 eligible individuals were stratified on the basis of the quartile distribution. Our results showed that the urinary Co level in males at the fourth quartile (Q4) was strongly correlated with increased FPG (β = 0.61, 95% CI: 0.17–1.04), HbA1c (β = 0.31, 95% CI: 0.09–0.54), insulin (β = 8.18, 95% CI: 2.84–13.52), and HOMA–IR (β = 3.42, 95% CI: 1.40–5.44) when compared with first quartile (Q1). High urinary Mo levels (Q4 vs. Q1) were associated with elevated FPG (β = 0.46, 95% CI: 0.17–0.75) and HbA1c (β = 0.27, 95% CI: 0.11–0.42) in the overall population. Positive linear dose-response associations were observed between urinary Co and insulin (Pnonlinear = 0.513) and HOMA–IR (Pnonlinear = 0.736) in males, as well as a positive linear dose-response relationship between urinary Mo and FPG (Pnonlinear = 0.826) and HbA1c (Pnonlinear = 0.376) in the overall population. Significant sex-specific and dose-response relationships were observed between urinary metals (Co and Mo) and diabetes-related indicators, and the potential mechanisms should be further investigated.
A novel sprayable adhesive is established (ZnMet-PF127) by the combination of a thermosensitive hydrogel (Pluronic F127, PF127) and a coordination complex of zinc and metformin (ZnMet). Here we demonstrate that ZnMet-PF127 potently promotes the healing of traumatic skin defect and burn skin injury by promoting cell proliferation, angiogenesis, collagen formation. Furthermore, we find that ZnMet could inhibit reactive oxygen species (ROS) production through activation of autophagy, thereby protecting cell from oxidative stress induced damage and promoting healing of skin wound. ZnMet complex exerts better effects on promoting skin wound healing than ZnCl2 or metformin alone. ZnMet complex also displays excellent antibacterial activity against Staphylococcus aureus or Escherichia coli, which could reduce the incidence of skin wound infections. Collectively, we demonstrate that sprayable PF127 could be used as a new drug delivery system for treatment of skin injury. The advantages of this sprayable system are obvious: (1) It is convenient to use; (2) The hydrogel can cover irregular skin defect sites evenly in a liquid state. In combination with this system, we establish a novel sprayable adhesive (ZnMet-PF127) and demonstrate that it is a potential clinical treatment for traumatic skin defect and burn skin injury.
In nature, the wind always fluctuates in magnitude. Hence, it is essential to consider the adaptability and durability of wind energy harvesters. This paper proposes a passively adaptive piezoelectric wind energy harvester with a double-airfoil bluff body to enhance performance subjected to time-varying wind velocity. The proposed double-airfoil bluff body is inspired by the fact that the attack angle can significantly affect the aerodynamic characteristics of the airfoil. An associated aero-electromechanical model is numerically developed to investigate the influence of the attack angle on the energy harvesting performance. Based on the aero-electromechanical model, the numerical results demonstrate three typical working modes that appear under different attack angles: vortex-induced vibration, galloping, and vibration suppression. These working modes can promise the proposed harvester to effectively and safely scavenge ambient wind energy. The physical mechanisms behind the three working modes are thoroughly explored given the work-energy principle and evolution of the vortex structure. The performance enhancement of the proposed harvester can be attributed to the positive aerodynamic work and an airfoil dynamic stall. Experiments are thereafter conducted to validate the theoretical results. Compared to the conventional galloping-based harvester with a square prism, the maximum voltage improvement percentage of the proposed harvester is over 62.3% within the investigated wind speed range when the attack angle is set to 10 • .
Liquid-liquid phase separation, and the resulted solute segregation, during conventional solidification have been a long-term challenge to produce copper (Cu)-iron (Fe) immiscible composites with high strength and high conductivity. The present work reports an effective solution to this issue through laser powder bed fusion (L-PBF) in-situ alloying of Cu-8 wt.% Fe. Microstructure observation showed that the fast cooling within micron-scale melt pools fully eliminated the Fe segregation and therefore the L-PBF fabricated nanocomposite achieved the homogeneous microstructure, which featured equiaxed fine grains around 1 µm in size. Ageing of the nanocomposite at 600°C for 1 h enabled precipitation of two types of nanoparticles. One is coarser Fe nanoprecipitates with body-centered cubic (BCC) structure and diameter of 100-300 nm, mainly distributing along grain boundaries. The other is smaller Fe nanoprecipitates with face-centered cubic (FCC) structure and diameter of 10-35 nm, being observed within the grains and having coherent interfaces with the Cu matrix. As a result, the aged Cu-Fe nanocomposite achieved tensile strength of 462.9±6.6 MPa with 30.4%±1.7% elongation to failure and 74.5% IACS (International Annealed Copper Standard) electrical conductivity. The formation mechanisms of the nanoprecipitates and the strengthening mechanisms of the nanocomposite are discussed.
Due to slow degradation and potentially carrying fungus of banana pseudo-stem, the irresponsibly disposed (such as optionally dumping and burning on the spot) of banana pseudo-stem caused severe environmental problems and fungus disease. However, the combustion efficiency of the banana pseudo-stem was limited by the higher moisture and lower heating value. The high-pressure CO2-hydrothermolysis provides an efficient strategy for upgrading the fuel quality and combustion characteristics. In this study, the combustion characteristics and emission analyses of the sample after and before treatment were investigated by TG–FTIR. Meanwhile, the oxidation reaction kinetics of the sample was established using the Friedman method. The results showed that the “coal-like” fuel, higher heating value (HHV) between 13.64 and 25.76 MJ/kg, was produced from banana pseudo-stem by the high-pressure CO2-hydrothermolysis. The ignition temperature of the sample after treatment is higher than that of the banana pseudo-stem. However, the combustion character index of the sample after treatment at 160 °C (BP-160) is the best among all samples, but that of the sample after treatment at 280 °C (BP-280) is the lowest. The sample after treatment has the higher combustion reactivity except for BP-280. The averaged activation energy values of the sample after treatment decrease with the increased temperature and are higher than that of BP, except for BP-280. The carbon emission (CO2 + CO), SO2 and N species emission (NO + N2O) was reduced during sample combustion after treatment. Overall, the high-pressure CO2-hydrothermolysis is a promising treatment technology for minimizing and energy utilization of banana waste.
This study reports an unusual martensitic strain accommodation mechanism, in an electron beam processed metastable β-Ti alloy, exhibiting a fine-grained microstructure with good yield strength and elastic modulus matching. Microstructural analysis reveals that ultra-fine laths of martensites were embedded within the fine-grained β structure. Detailed TEM and orientation relationship analyses further unravel that the observed microstructure consists of α'' martensites associated with different habit plane and transformation twins, one with {7 10 0} α'' //{755} β type habit plane and forming {111} α'' type I twin while another with {471} α'' //{443} β type habit plane, forming a {351}<211> α'' type II twin. This structure can be interpreted as the product of rapid solidification and thermal stress relaxation which manipulated the formation of distinct martensites that originates from the fluctuated lattice instability, lattice distortion, and transformation strain. This finding provides an alternative route for utilizing the martensitic strain accommodation mechanism, benefiting additive manufacturing β-Ti alloy components with desired mechanical performance.
A complete dessin of order {m,n} is an orientable map with underlying graph being a complete bipartite graph Km,n, which is said to be regular if all edges are equivalent under the automorphism group, and circular if the boundary cycle of each face is a circuit. As one of a series papers towards a classification of complete circular regular dessins of order {m,n}, this paper presents such a classification for the case where m,n are coprime.
The gut-lung axis has been implicated as a potential therapeutic target in lung disorders. While increasing evidence suggests that gut microbiota plays a critical role in regulating host immunity and contributing to tuberculosis (TB) development and progression, the underlying mechanisms whereby gut microbiota may impact TB outcomes are not fully understood. Here, we found that broad-spectrum antibiotics treatment increased susceptibility to Mycobacterium tuberculosis (M. tuberculosis) infection and modulated pulmonary inflammatory responses in mouse M. tuberculosis infection model. We then identified a commensal gut bacteria-regulated lncRNA, termed lncRNA-CGB, which was down-regulated by dysbiosis of gut microbiota during TB infection. Furthermore, we found that Bacteroides fragilis (B. fragilis) was a direct regulator of lncRNA-CGB, and oral administration of B. fragilis enhanced expression of lncRNA-CGB and promoted anti-TB immunity. Genomic knock-out of lncRNA-CGB led to reduced IFN-γ expression and impaired anti-TB immunity, therefore leading to detrimental effects on M. tuberculosis infection. Mechanistically, lncRNA-CGB interacted with EZH2 and negatively regulated H3K27 tri-methylation (H3K27Me3) epigenetic programming, leading to enhanced IFN-γ expression. Thus, this work not only uncovered previously unrecognized importance of gut bacteria-lncRNA-EZH2-H3K27Me3 axis in conferring immune protection against TB but also identified a potential new paradigm to develop a microbiota-based treatment against TB and potentially other diseases.
Emerging drug resistance is generating an urgent need for novel and effective antibiotics. A promising target that has not yet been addressed by approved antibiotics is the bacterial DNA gyrase subunit B (GyrB), and GyrB inhibitors could be effective against drug-resistant bacteria, such as methicillin-resistant S. aureus (MRSA). Here, we used the 4-hydroxy-2-quinolone fragment to search the Specs database of purchasable compounds for potential inhibitors of GyrB and identified AG-690/11765367, or f1, as a novel and potent inhibitor of the target protein (IC50: 1.21 µM). Structural modification was used to further identify two more potent GyrB inhibitors: f4 (IC50: 0.31 µM) and f14 (IC50: 0.28 µM). Additional experiments indicated that compound f1 is more potent than the others in terms of antibacterial activity against MRSA (MICs: 4–8 µg/mL), non-toxic to HUVEC and HepG2 (CC50: approximately 50 µM), and metabolically stable (t1/2: > 372.8 min for plasma; 24.5 min for liver microsomes). In summary, this study showed that the discovered N-quinazolinone-4-hydroxy-2-quinolone-3-carboxamides are novel GyrB-targeted antibacterial agents; compound f1 is promising for further development.
The renewable biofuel n-butanol is an alternative to gasoline and diesel in internal combustion engines. The addition of aluminum nanoparticles (ANPs) would improve the performance of these nanofluid fuels. The reactive dynamics simulation of the ignition and combustion process of ANP/n-butanol nanofluid fuel was carried out. The combustion mechanisms of n-butanol fuel with and without ANPs, as well as the aggregation of nanodroplets and the sintering degree of nanoparticles were explored. Simulation results show that the combustion of aluminum-based n-butanol fluid fuel undergoes a three-stage: chain expansion, micro-explosion, and steady reaction. In general, the addition of ANPs improves combustion completeness and reduces the ignition delay of n-butanol. The kinetic calculations show that the activation energy of n-butanol combustion is reduced by 39.9%. A new reaction mechanism was proposed from the results: n-butanol reacts with oxygen free radicals generated by Al rather than O 2. On the other hand, n-butanol prevents the aggregation and sintering of aluminum nanoparticles. Therefore, the ANP additives and n-butanol nanofluid promote mutually in the combustion. This work is expected to guide the practical application of aluminum-based alcohol fuels.
Meteorological drought is generally regarded as the cause of other types of droughts. This study firstly analyzed the characteristics of meteorological drought and hydrological drought in different climate regions all over the world during a long time period (1902-2014); then, the maximum Pearson correlation coefficients (MPCC) of meteorological drought and hydrological drought at different time scales were calculated to determine the drought response time (DRT) in each climate region. The results revealed that: 1) meteorological drought in most climate regions intensified during 1902-1958 but showed a wetting trend during 1959-2014. Compared with the characteristics of meteorological drought, the change of hydrological drought was slightly different. Hydrological drought weakened during 1902-1958 but intensified slightly during 1959-2014; however, the magnitude of the changing rate was relatively small. 2) The drought response relationship in the Cf (i.e., continental wet warm) climate region was the strongest, and that in the E (i.e., polar) climate region was the weakest. 3) Globally, the DRTs in various climate regions were mainly 5-10 months, which were mainly related to the climate type. The outcomes of this study can provide a reference for further revealing the propagation mechanism from meteorological drought to hydrological drought in different climate regions.
The application of ionic liquids in perovskite has attracted wide-spread attention for its astounding performance improvement of perovskite solar cells (PSCs). However, the detailed mechanisms behind the improvement remain mysterious. Herein, a series of imidazolium-based ionic liquids (IILs) with different cations and anions is systematically investigated to elucidate the passivation mechanism of IILs on inorganic perovskites. It is found that IILs display the following advantages: (1) They form ionic bonds with Cs ⁺ and Pb ²⁺ cations on the surface and at the grain boundaries of perovskite films, which could effectively heal/reduce the Cs ⁺ /I ⁻ vacancies and Pb-related defects; (2) They serve as a bridge between the perovskite and the hole-transport-layer for effective charge extraction and transfer; and (3) They increase the hydrophobicity of the perovskite surface to further improve the stability of the CsPbI 2 Br PSCs. The combination of the above effects results in suppressed non-radiative recombination loss in CsPbI 2 Br PSCs and an impressive power conversion efficiency of 17.02%. Additionally, the CsPbI 2 Br PSCs with IILs surface modification exhibited improved ambient and light illumination stability. Our results provide guidance for an in-depth understanding of the passivation mechanism of IILs in inorganic perovskites."Image missing"
Flexible pressure sensors with high sensitivity are desired in the fields of electronic skins, human–machine interfaces, and health monitoring. Employing ionic soft materials with microstructured architectures in the functional layer is an effective way that can enhance the amplitude of capacitance signal due to generated electron double layer and thus improve the sensitivity of capacitive-type pressure sensors. However, the requirement of specific apparatus and the complex fabrication process to build such microstructures lead to high cost and low productivity. Here, we report a simple strategy that uses open-cell polyurethane foams with high porosity as a continuous three-dimensional network skeleton to load with ionic liquid in a one-step soak process, serving as the ionic layer in iontronic pressure sensors. The high porosity (95.4%) of PU-IL composite foam shows a pretty low Young’s modulus of 3.4 kPa and good compressibility. A superhigh maximum sensitivity of 9,280 kPa ⁻¹ in the pressure regime and a high pressure resolution of 0.125% are observed in this foam-based pressure sensor. The device also exhibits remarkable mechanical stability over 5,000 compression-release or bending-release cycles. Such high porosity of composite structure provides a simple, cost-effective and scalable way to fabricate super sensitive pressure sensor, which has prominent capability in applications of water wave detection, underwater vibration sensing, and mechanical fault monitoring.
The orientation of fluorophores can reveal crucial information about the structure and dynamics of their associated subcellular organelles. Despite significant progress in super-resolution, fluorescence polarization microscopy remains limited to unique samples with relatively strong polarization modulation and not applicable to the weak polarization signals in samples due to the excessive background noise. Here we apply optical lock-in detection to amplify the weak polarization modulation with super-resolution. This novel technique, termed optical lock-in detection super-resolution dipole orientation mapping (OLID-SDOM), could achieve a maximum of 100 frames per second and rapid extraction of 2D orientation, and distinguish distance up to 50 nm, making it suitable for monitoring structural dynamics concerning orientation changes in vivo. OLID-SDOM was employed to explore the universal anisotropy of a large variety of GFP-tagged subcellular organelles, including mitochondria, lysosome, Golgi, endosome, etc. We found that OUF (Orientation Uniformity Factor) of OLID-SDOM can be specific for different subcellular organelles, indicating that the anisotropy was related to the function of the organelles, and OUF can potentially be an indicator to distinguish normal and abnormal cells (even cancer cells). Furthermore, dual-color super-resolution OLID-SDOM imaging of lysosomes and actins demonstrates its potential in studying dynamic molecular interactions. The subtle anisotropy changes of expanding and shrinking dendritic spines in live neurons were observed with real-time OLID-SDOM. Revealing previously unobservable fluorescence anisotropy in various samples and indicating their underlying dynamic molecular structural changes, OLID-SDOM expands the toolkit for live cell research.
Airflow sensors are an essential component in a wide range of industrial, biomedical, and environmental applications. The development of compact devices with a fast response and wide measurement range capable of in situ airflow monitoring is highly desirable. Herein, we report a miniaturized optical airflow sensor based on a GaN chip with a flexible PDMS membrane. The compact GaN chip is responsible for light emission and photodetection. The PDMS membrane fabricated using a droplet-based molding process can effectively transform the airflow stimuli into optical reflectance changes that can be monitored by an on-chip photodetector. Without the use of external components for light coupling, the proposed sensor adopting the novel integration scheme is capable of detecting airflow rates of up to 53.5 ms ⁻¹ and exhibits a fast response time of 12 ms, holding great promise for diverse practical applications. The potential use in monitoring human breathing is also demonstrated.
Intervertebral disc (IVD) degeneration (IVDD) is the main cause of low back pain with major social and economic burdens; however, its underlying molecular mechanisms remain poorly defined. Here we show that the focal adhesion protein Kindlin-2 is highly expressed in the nucleus pulposus (NP), but not in the anulus fibrosus and the cartilaginous endplates, in the IVD tissues. Expression of Kindlin-2 is drastically decreased in NP cells in aged mice and severe IVDD patients. Inducible deletion of Kindlin-2 in NP cells in adult mice causes spontaneous and striking IVDD-like phenotypes in lumbar IVDs and largely accelerates progression of coccygeal IVDD in the presence of abnormal mechanical stress. Kindlin-2 loss activates Nlrp3 inflammasome and stimulates expression of IL-1β in NP cells, which in turn downregulates Kindlin-2. This vicious cycle promotes extracellular matrix (ECM) catabolism and NP cell apoptosis. Furthermore, abnormal mechanical stress reduces expression of Kindlin-2, which exacerbates Nlrp3 inflammasome activation, cell apoptosis, and ECM catabolism in NP cells caused by Kindlin-2 deficiency. In vivo blocking Nlrp3 inflammasome activation prevents IVDD progression induced by Kindlin-2 loss and abnormal mechanical stress. Of translational significance, adeno-associated virus-mediated overexpression of Kindlin-2 inhibits ECM catabolism and cell apoptosis in primary human NP cells in vitro and alleviates coccygeal IVDD progression caused by mechanical stress in rat. Collectively, we establish critical roles of Kindlin-2 in inhibiting Nlrp3 inflammasome activation and maintaining integrity of the IVD homeostasis and define a novel target for the prevention and treatment of IVDD.
Networks based on carbon nanotube (CNT) have been widely utilized to fabricate flexible electronic devices, but defects inevitably exist in these structures. In this study, we investigate the influence of the CNT-unit defects on the mechanical properties of a honeycomb CNT-based network, super carbon nanotube (SCNT), through molecular dynamics simulations. Results show that tensile strengths of the defective SCNTs are affected by the defect number, distribution continuity and orientation. Single-defect brings 0 ~ 25% reduction of the tensile strength with the dependency on defect position and the reduction is over 50% when the defect number increases to three. The distribution continuity induces up to 20% differences of tensile strengths for SCNTs with the same defect number. A smaller arranging angle of defects to the tensile direction leads to a higher tensile strength. Defective SCNTs possess various modes of stress concentration with different concentration degrees under the combined effect of defect number, arranging direction and continuity, for which the underlying mechanism can be explained by the effective crack length of the fracture mechanics. Fundamentally, the force transmission mode of the SCNT controls the influence of defects and the cases that breaking more force transmission paths cause larger decreases of tensile strengths. Defects are non-negligible factors of the mechanical properties of CNT-based networks and understanding the influence of defects on CNT-based networks is valuable to achieve the proper design of CNT-based electronic devices with better performances. Graphical Abstract
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4,090 members
Yongsheng Ma
  • Department of Mechanical and Energy Engineering
Yu Liu
  • Department of Mechanics and Aerospace Engineering
Chang Alex Zou
  • Clinical Medical Research Center The First Affiliated Hospital
Lu Fan
  • Department of Ocean Science and Engineering
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Qikun Xue
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