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Existing structures may suffer from resistance deterioration due to repeated attacks. The modeling of resistance deterioration is a critical ingredient in the reliability assessment and service life prediction of these degraded structures. In this paper, an explicit compound Poisson process-based model is developed to describe the shock deterioration of structural resistance, where the magnitude of each shock deterioration increment is modeled by a Gamma-distributed random variable. The moments (mean value and variance) and the distribution function of the cumulative shock deterioration are derived in a closed form, based on a proposed W-function. A method for the efficient calculation of the W-function is presented, which reduces to the Bessel type I function if the shock deterioration increment is exponentially distributed (a special case of Gamma distribution). The proposed shock deterioration model is applicable to either a stationary or a nonstationary Poisson process of random jumps. Subsequently, the overall resistance deterioration is modeled as the linear combination of gradual and shock deteriorations, based on which the proposed model can be used in the time-dependent reliability assessment of aging structures efficiently. A numerical example is presented to demonstrate the applicability of the proposed deterioration model by estimating the time-dependent reliability of an aging bridge. It is found that a smaller threshold for the degraded resistance leads to greater mean value and standard deviation of the time to failure, and this effect is enhanced by a smaller occurrence rate of the shock deterioration.

The dramatic tropical cyclone (TC) damages in coastal areas around the world have gained significant attention from asset owners, policy makers and engineers. The estimate of TC damage for a specific region of interest is informative of the preparedness and resilience of the area subjected to TC hazards, and thus should be conducted using a quantitative approach. A reasonable indicator of TC damage should incorporate not only the TC characteristics (e.g., intensity, frequency and duration) but also the vulnerability of the TC-prone areas. In this paper, a new indicator is proposed to measure the TC threat, which takes into account both the TC characteristics and the vulnerability of the area. The indicator has two forms: the first one considers the maximum wind speed only and the second incorporates the integrated wind speed profile. The historical damage scenarios along the US East Coast, as well as those in Hong Kong, China, are examined to demonstrate the applicability of the proposed indicator. Results show that the proposed indicator is capable of representing the impact of TC wind field profile on the TC damage costs. The proposed indicator could be further used to project the future TC damages for areas subjected to TC hazards.

This paper proposes explicit approaches for time-dependent reliability assessment of aging structures, taking into account the correlation associated with the load process and that arising from the resistance deterioration process. For the load process, temporal correlation may arise due to the impacts of underlying common causes. With this regard, a closed-form solution is developed for structural reliability, which models the sequence of load effects as a Markov process. Furthermore, the resistance deterioration is by nature a non-increasing stochastic process with autocorrelation on the temporal scale. The Gamma process is used to describe the stochastic behaviour of resistance deterioration, based on which an explicit reliability method is derived. The proposed reliability methods are straightforward to implement and thus are promising to be adopted in practical engineering regarding the safety evaluation of aging structures. Illustrative examples are presented to demonstrate the accuracy and applicability of the proposed approaches.

The development of photosensitive slurries for additive manufacturing has attracted great interest due to their correlation with the final properties of the fabricated parts. This paper focus on the printing quality control in digital light processing (DLP) 3D printing of advanced ceramics. Systematic experiments were performed to assess the effects of the exposure time and printing angle on the three-point bending strength of the fabricated samples. The exposure time affected the bending strength of the printed zirconia ceramic dramatically. When the weak exposure time is 1 s and the strong exposure time is 13 s, the average bending strength can reach 580 MPa while Weibull modulus can reach 8.84. Meanwhile, the printing angle also affected the bending strength mechanical sample printed at 45° exhibits the worst performance.

Solid Oxide Fuel Cells (SOFCs) are environmentally efficient energy conversion devices, but are partially limited by the complicated fabrication procedure. In this work, dense 8 mol% yttria-stabilized zirconia (8YSZ) ceramics were successfully realized through a DLP (digital light processing) stereolithography method and the electrolyte self-supported fuel cell was also tested at 800 °C. The sintering behavior of the as-printed planar samples were investigated and a fully dense ceramic can be achieved at 1450 °C. The total conductivity of the sintered 8YSZ can reach 2.18 × 10−2 S cm−1 at a test temperature of 800 °C, which is acceptable for practical application. For the electrolyte self-supported fuel cell test, a power density of 114.3 mW cm−2 can be achieved when Ni-8YSZ cermet and La0.8Sr0.2MnO3 (LSM) were used as anode and cathode. It was demonstrated that 3D printing is a promising processing technique to build up electrolyte self-supported SOFCs with desired structure for the future development.

The environmental or anthropogenic factors, to which the in-service bridges are subjected, are responsible for the reduction of bridge performance, and finally lead to great service risk for bridges and increase the probability of substantial economic losses. Probability-based estimate of bridge resistance is an essential indicator for the bridge condition evaluation and for optimization of bridge maintenance/repair decisions. It places an emphasis on the proper probabilistic models of structural properties and assessment methods. Making full use of historical service load information may improve the accuracy of bridge performance assessment with reduced epistemic uncertainty for existing aging bridges. In to-date analyses to update the bridge resistance with past service information, the models of resistance deterioration have been assumed as either deterministic or fully correlated, which may differ significantly from the realistic case. With this regard, this paper proposes a novel method for updating the resistance of service-proven bridges with a realistic deterioration model. The Gamma stochastic process has been suggested in the literature to describe the probabilistic behavior of structural time-dependent resistance and thus is adopted in this paper. An illustrative bridge is presented to demonstrate the applicability of the proposed method. Parametric examples are conducted to investigate the role of resistance deterioration model in the updated estimate of bridge resistance with historical service information. Keywords: Existing aging bridges, Historical load information, Resistance updating, Gamma deterioration process, Bridge safety

In probabilistic analyses and structural reliability assessments, it is often difficult or infeasible to reliably identify the proper probabilistic models for the uncertain variables due to limited supporting databases, e.g., limited observed samples or physics-based inference. To address this difficulty, a probability-bounding approach can be utilized to model such imprecise probabilistic information, i.e., considering the bounds of the (unknown) distribution function rather than postulating a single, precisely specified distribution function. Consequently, one can only estimate the bounds of the structural reliability instead of a point estimate. Current simulation technologies, however, sacrifice precision of the bound estimate in return for numerical efficiency through numerical simplifications. Hence, they produce overly conservative results in many practical cases. This paper proposes a linear programming-based method to perform reliability assessments subjected to imprecisely known random variables. The method computes the tight bounds of structural failure probability directly without the need of constructing the probability bounds of the input random variables. The method can further be used to construct the best-possible bounds for the distribution function of a random variable with incomplete statistical information.

Background Cardiac hypertrophy is a serious factor underlying heart failure. Although a large number of pathogenic genes have been identified, the underlying molecular mechanisms of cardiac hypertrophy are still poorly understood. MicroRNAs are a class of small non-coding RNAs which regulate their target genes at the post-transcriptional level. L-type calcium channels play important role in hypertrophic signaling pathways, and CACNA1C is encoded by L-type calcium channels. Here, we hypothesize that the overexpression of miR-135b can attenuate hypertrophy by targeting CACNA1C. Methods We test the functional involvement of miR-135b in cardiac hypertrophy model. In order to evaluate the effect of miR-135b in cardiac hypertrophy, miR-135b mimic, miR-135b agomir and α-MHC-miR-135b transgenic mice were used for the overexpression of miR-135b. Luciferase reporter assays were used to testify the binding of miR-135b to the CACNA1C 3′UTR. Results Our results revealed that in a pathological cardiac hypertrophy model, the expression of miR-135b was clearly downregulated. Hypertrophic marker genes were upregulated after the knockdown of miR-135b in vitro, while the overexpression of miR-135b attenuated hypertrophy. These results suggested that miR-135b may weaken hypertrophic signals. We then explored the mechanism of miR-135b in hypertrophy and identified that CACNA1C was a target gene for miR-135b. The overexpression of miR-135b attenuated cardiac hypertrophy by targeting CACNA1C. Conclusions Our studies revealed that miR-135b is a critical regulator of cardiomyocyte hypertrophy. Our findings may provide a novel strategy for the treatment of cardiac hypertrophy.

Scar formation can lead to glaucoma filtration surgery (GFS) failure, wherein transforming growth factor (TGF)-β is the core regulator. To reducing scar formation, this paper presents our study on the design of hydrogels to deactivate TGF-β1. We hypothesized that excess TGF-β1 can be removed from aqueous humor through the addition of oxidized hyaluronic acid (O-HA) hydrogels that are seeded with decorin (O-HA ​+ ​D). Immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) were performed to demonstrate the adsorption properties of O-HA ​+ ​D hydrogel, thus reducing the TGF-β1 concentration in aqueous humor. In the light that collagen contraction in human Tenon's capsule fibroblasts (HTFs) and the angiogenesis of human umbilical vein endothelial cells (HUVECs) can be activated by TGF-β1 and β2, we performed the quantitative analysis of polymerase chain reaction to determine the effect of O-HA ​+ ​D on the type I collagen, fibronectin, and angiogenesis. Our results illustrate that O-HA ​+ ​D can inhibit the increase of α-SMA expression in HTF induced by TGF-β1 and that O-HA ​+ ​D can inhibit the production of collagen I and fibronectin in HTF treated with TGF-β1. Furthermore, we performed in vivo studies by employing a rabbit model, where rabbits were treated with hydrogels post GFS. Our results demonstrate that, as compared with other groups, the rabbits treated with O-HA ​+ ​D had the greatest reduction in inflammatory cells with reduced level of collagen in wounds. Taken together, the present study paves the way toward the treatment of post-glaucoma fibrosis following surgery.

Neuroinflammation is one of the major processes that trigger neuropathological amyloid-β (Aβ) deposition and contribute to Alzheimer’s disease (AD) progression. Naked mole rats, which are the longest living rodents and exhibit negligible senescence, have a special brain microenvironment characterized by high-molecular-mass hyaluronan (HMM-HA) and high levels of neuregulin 1 (NRG1), which are related to resistance to neuroinflammation and Aβ deposition, leading to protection from AD. Thus, mimicking the unique brain microenvironment of the naked mole rat as a strategy for AD treatment is of critical interest. Here, naked mole rat HMM-HA and NRG1 were used to establish an injectable neuroinflammation-responsive triglycerol monostearate (TM)-HA-NRG1 hydrogel to alter the brain microenvironment in the early to late stages of AD. Intracerebroventricular (ICV) delivery of the hydrogel resulted in significant mitigation of Aβ plaque formation and complement C1q deposition in the hippocampus. Interestingly, we found that C1q deposition on pericytes was probably associated with capillary dysfunction. Furthermore, continuous intervention obviously reduced C1q deposition on pericytes and improved the oxygen supply to the brain. Importantly, in 16-month-old AD mice, cognitive decline was significantly ameliorated after TM-HA-NRG1 hydrogel treatment. Thus, the work reported here provides a potential early intervention strategy for retarding later AD progression.

(CoCrFeNi)94Ti2Al4 high entropy alloy (HEA) was fabricated through drop-casting and conventional thermo-mechanical processing. After cold rolling and recrystallization heat treatments, the tensile properties were investigated at room temperature (RT), 573 K, and 873 K, respectively. At RT, the stress-strain curve exhibits non-serration. However, with the increasing tensile temperature from 573 K to 873 K, the serration evolves from type A + B to type C, and the maximum stress drop rises from 15.0 MPa to 24.7 MPa. At 873 K, C-type serration first appears at the yield strain, but finally disappears when the plastic strain above 12%. Transmission electron microscopy (TEM) analysis indicates that the simultaneous effects of twinning boundary and high density dislocations promote the dynamic precipitation of nanoscale L21-Heusler phase during tensile deformation.

Background: This study purposed to construct a widely accepted prognostic nomogram in Chinese high-grade osteosarcoma (HOS) patients aged ≤ 30 years to provide insight into predicting 5-year overall survival (OS). Methods: Data of 503 consecutive HOS patients at our centre between 12/2012 and 05/2019 were retrospectively collected. The 84 clinical features, routine laboratory haematological and biochemical testing indicators of each patient at the time of diagnosis were collected. A prognostic nomogram model for predicting OS was constructed based on Cox proportional hazards model. The performance was assessed by concordance index (C-index), receiver operating characteristic curve and calibration curve. The utility was evaluated by decision curve analysis. Findings: The 5-year OS was 52.1% and 2.6% for the nonmetastatic and metastatic patients, respectively. The nomogram included nine important variables based on a multivariate analysis: tumour stage, surgical type, metastasis, preoperative neoadjuvant chemotherapy cycle, postoperative metastasis time, mean corpuscular volume, tumour-specific growth factor, gamma-glutamyl transferase and creatinine. The calibration curve showed that the nomogram was able to predict 5-year OS accurately. The C-index of the nomogram for OS prediction was 0.795 (range, 0.703-0.887). Moreover, the decision curve analysis curve also demonstrated the clinical benefit of this model. Interpretation: The nomogram provides an individualized risk estimate of the 5-year OS in patients with HOS aged ≤ 30 years in a Chinese population-based cohort. Funding Statement: This work was financially funded by the National Science Foundation of China (No. U1702283, 81972764, 81960488, 81760520, 81560471), the Joint Special Funds for the Department of Science and Technology of Yunnan Province-Kunming Medical University (No. 2017FE467-073, 2018FE001-060, 2019FE001-152, 2019FE001-078), the Scientific Research Projects of Internal Research Institutions of Medicine (Nos. 2017NS196, 2017NS197, 2018NS069, 2018NS070), the Medical Leaders of Yunnan Province (No. D-201603), the Foundation of the Young and Middle-aged Academic and Technical Leaders of Yunnan Province (No. 2017HB051), China Postdoctoral Science Foundation (No. 2018M643798XB), Training program for 100 Young and middle-aged Academic and technical backbones of Kunming Medical University and the Major Scientific and Technological Achievement Cultivation Project of Kunming Medical University (No. CGPY201703). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: All human tissue experiments were approved by the Institutional Ethics Committee of the Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital). Written informed consent forms for the experimental studies were obtained from the patients or their guardians.

Tropical cyclones (TCs) are among the most costly natural hazards affecting civil construction in coastal areas, which have caused extensive economic losses and social disruption world-widely. Moreover, the intensity and/or frequency of future TCs have been projected to change with time due to the potential impacts of climate change, indicating the potential of ever larger TC damages for coastal regions. The estimate of future TC damage should be conducted under a probability-based framework, taking into account the uncertainties associated with both the TC characteristics (e.g., intensity and frequency) and the vulnerability of the coastal communities of interest. In this paper, an explicit approach is developed to evaluate the TC damage for TC-prone areas considering the potential impacts of climate change. The mean value and variance, as well as the cumulative density function of cumulative TC damage are estimated quantitatively. The proposed method is applied to TC damage assessment of Hong Kong, China – a TC-prone area which has suffered severely from historical cyclones. Sensitivity analysis is also performed to investigate the impacts of the time-variant characteristics of both the TC process and the TC damage conditional on one TC event on the cumulative damage costs for coastal areas.

Aging of structural performance and significant external loads may impair structural safety and serviceability and cause potential economic losses. In the presence of uncertainties associated with both resistance deterioration and external loads, structural safety shall be estimated quantitatively under a probability-based framework. A stochastic load process is often auto-correlated on the temporal scale, with correlations arising from both the occurrence times and intensities. Moreover, a deterioration process is physically dependent on the load magnitudes. This paper investigates the impacts of load temporal correlation and deterioration-load dependency on time-variant structural reliability. The load occurrence process is modeled as a Poisson point process with correlated separation time between two load events. The correlation between the intensities of load events is described by the multi-variate Gaussian copula function. The resistance aging process is considered to be a combination of both gradual and shock deteriorations. Four candidate copula functions, namely Gaussian, Clayton, Gumbel and Frank, are considered to model the dependency of shock deterioration on load intensity. Two types of failure mechanisms are considered: the first is due to the load effect exceeding the resistance, and the second occurs when the cumulative damage within the considered service period reaches the permissible level. A simulation-based method is developed to estimate structural reliability considering the two failure modes. Illustrative examples are presented to demonstrate the applicability of the proposed method. Parametric studies are conducted to investigate the impacts of temporal correlation in loads and deterioration-load dependency on structural failure probability.

A member of antiperovskite manganese compound Mn3PdN was successfully synthesized. The structural, magnetic, electrical, and thermal transport properties were investigated systematically. The results indicated that Mn3PdN is a weak correlated system. A first-order paramagnetic (PM) to antiferromagnetic (AFM) transition occurred at 285 ​K (TN) combining with an abrupt change in structure. Mn3PdN exhibits multifunctional properties such as near-zero temperature coefficient of resistivity (TCR) and negative thermal expansion (NTE).