Search

Abstract Background Career calling, professional identity and the need for achievement are believed to affect the students’ learning engagement and effect. However, their regulatory relationship with medical students remains unclear. Methods Our study surveyed 1250 medical students through a questionnaire, and the correlation of the study variables was analysed. Harman’s Single-Factor test was performed on the data to rule out significant common method biases. The mediation effect was determined using the percentile Bootstrap method with deviation correction. Results Career calling was positively correlated with professional identity (r = 0.51, p

In radioactivity analysis, counting efficiency(E) and background(to be precise, it should be deterministic background) are usually discussed, but apparent counting efficiency(E') and random background are rarely mentioned. However, the influence of background(including both deterministic background and random background) on apparent counting efficiency must be considered, especially for samples with low radioactivity. The relation between E and E' can be described as the equation E' = E + ΔB/A, where A is the sample radioactivity, and ΔB is the residue background, including two parts: the counting rate of residual deterministic background caused by inaccurate deduction of background and the counting rate of random background that cannot be deducted. In this paper, E' was studied on the following assumptions: E was fixed at 90%; A was changing from 0.1 to 100, with a step of 0.1(relative unit, similarly hereinafter); and ΔB was set to be fixed, or to follow a specific distribution. The simplest continuous distribution(uniform distribution) and the most commonly used continuous distribution(normal distribution) were chosen for this research, and the function “random number generator ” of the software Excel was used to simulate the random variable ΔB. Specifically speaking, the random variable ΔB was assumed to follow ±0.1·U(0,1), ±0.1·U(−0.5,0.5), ±0.1·N(0.5,1), or ±0.1·N(0,1), where U stands for uniform distribution and N for normal distribution. The influence of background on apparent counting efficiencies is divided into two aspects: one is the systematic error introduced by inaccurate background deduction, which makes all apparent counting efficiencies deviate from the counting efficiency in the same direction; the other is the accidental error caused by background fluctuations, which makes apparent counting efficiency fluctuate within a certain range. Regardless of the error type, the influence of background on apparent counting efficiency will increase as the radioactivity of the sample decreases. For samples with high radioactivity, the difference between apparent counting efficiency and counting efficiency is so small that it can be ignored, therefore it is not necessary to distinguish between the two concepts of apparent counting efficiency and counting efficiency; but for samples with low radioactivity, they must be used differently. Unless there is no standard sample with high radioactivity, it is not recommended to use the inefficient method, which is reported in Lin’s paper(ACS Earth Space Chem, 2022, 6(7): 1868-1875), to obtain counting efficiency by measuring a large number of samples with low radioactivity. It is advisable to obtain counting efficiency by measuring standard samples with sufficiently high radioactivity, in which the influence of background can be negligible.

Economic and active nitrogen (N2) is used as a shielding gas for the wire-arc additive manufacturing (WAAM) of Al-matrix composite (AMC). Although no crack was found, large flaky nitrides up to 500 μm are generated in the matrix of the Al alloy, leading to a significant deterioration in both plasticity (reduced by 81.4%) and tensile strength (reduced by 17.5%) compared with the deposit protected by argon (Ar), which is to be modified. Then, FSP was performed on the matrix of the Al alloy. The influence of friction stir processing (FSP) on the microstructure and mechanical properties in the stirred zone (SZ) of WAAM 5356 Al alloy deposit, prepared under a N2 environment, was studied. Flaky nitrides were observed in the Al matrix, and were broken due to FSP. The large flaky nitrides with a length of 500 μm were broken into granular nitrides with sizes lower than 2 μm. The grain size in the SZ decreased by 83% after FSP, and the microhardness in the SZ became more uniform, with an average value of 91.9 HV. Owing to the refinement of AlN by FSP, the tensile strength and elongation of the AMC were 349 MPa and 19.9%, much more than that before FSP of 231 MPa and 5.5%, showing an increase of 51.1% and 261.8%, respectively. The plasticity has obvious improvement, which is higher than the common used stir casting AMC.

Abstract To accelerate the pace in the field of photothermal therapy (PTT), it is urged to develop easily accessible photothermal agents (PTAs) showing high photothermal conversion efficiency (PCE). As a proof‐of‐concept, hereby a conventional strategy is presented to prepare donor–acceptor (D–A) structured PTAs through cycloaddition‐retroelectrocyclization (CA–RE) reaction, and the resultant PTAs give high PCE upon near‐infrared (NIR) irradiation. By joint experimental‐theoretical study, these PTAs exhibit prominent D–A structure with strong intramolecular charge transfer (ICT) characteristics and significantly twisting between D and A units which account for the high PCEs. Among them, the DMA‐TCNQ exhibits the strongest absorption in NIR range as well as the highest PCE of 91.3% upon irradiation by 760‐nm LED lamp (1.2 W cm−2). In vitro and in vivo experimental results revealed that DMA‐TCNQ exhibits low dark toxicity and high phototoxicity after IR irradiation along with nude mice tumor inhibition up to 81.0% through intravenous therapy. The findings demonstrate CA–RE reaction as a convenient approach to obtain twisted D–A structured PTAs for effective PTT and probably promote the progress of cancer therapies.

The human eye is susceptible to various disorders that affect its structure or function, including glaucoma, age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitochondrial dysfunction has been identified as a critical factor in the pathogenesis and progression of eye disorders, making it a potential therapeutic target in the clinic. Natural products have been used in traditional medicine for centuries and continue to play a significant role in modern drug development and clinical therapeutics. Recently, there has been a surge in research exploring the efficacy of natural products in treating eye disorders and their underlying physiological mechanisms. This review aims to discuss the involvement of mitochondrial dysfunction in eye disorders and summarize the recent advances in the application of natural products targeting mitochondria. In addition, we describe the future perspective and challenges in the development of mitochondria-targeting natural products.

Abstract Background Preimplantation genetic testing for aneuploidy (PGT-A) was demonstrated to be superior to conventional IVF in reducing the incidence of miscarriage and abnormal offspring after the first embryo transfer (ET). PGT-A requires several embryo trophectoderm cells, but its negative impacts on embryo development and long-term influence on the health conditions of conceived children have always been a concern. As an alternative, noninvasive PGT-A (niPGT-A) approaches using spent blastocyst culture medium (SBCM) achieved comparable accuracy with PGT-A in several pilot studies. The main objective of this study is to determine whether noninvasive embryo viability testing (niEVT) results in better clinical outcomes than conventional IVF after the first embryo transfer. Furthermore, we further investigated whether niEVT results in higher the live birth rate between women with advanced maternal age (AMA, > 35 years old) and young women or among patients for whom different fertilization protocols are adopted. Methods This study will be a double-blind, multicenter, randomized controlled trial (RCT) studying patients of different ages (20–43 years) undergoing different fertilization protocols (in vitro fertilization [IVF] or intracytoplasmic sperm injection [ICSI]). We will enroll 1140 patients at eight reproductive medical centers over 24 months. Eligible patients should have at least two good-quality blastocysts (better than grade 4 CB). The primary outcome will be the live birth rate of the first embryo transfer (ET). Secondary outcomes will include the clinical pregnancy rate, ongoing pregnancy rate, miscarriage rate, cumulative live birth rate, ectopic pregnancy rate, and time to pregnancy. Discussion In this study, patients who undergo noninvasive embryo viability testing (niEVT) will be compared to women treated by conventional IVF. We will determine the effects on the pregnancy rate, miscarriage rate, and live birth rate and adverse events. We will also investigate whether there is any difference in clinical outcomes among patients with different ages and fertilization protocols (IVF/ICSI). This trial will provide clinical evidence of the effect of noninvasive embryo viability testing on the clinical outcomes of the first embryo transfer. Trial registration Chinese Clinical Trial Registry (ChiCTR) Identifier: ChiCTR2100051408. 9 September 2021.

Abstract It is long been suggested that one‐carbon metabolism (OCM) is associated with Alzheimer's disease (AD), whereas the potential mechanisms remain poorly understood. Taking advantage of chemical biology, that mitochondrial serine hydroxymethyltransferase (SHMT2) directly regulated the translation of ADAM metallopeptidase domain 10 (ADAM10), a therapeutic target for AD is reported. That the small‐molecule kenpaullone (KEN) promoted ADAM10 translation via the 5′ untranslated region (5′UTR) and improved cognitive functions in APP/PS1 mice is found. SHMT2, which is identified as a target gene of KEN and the 5′UTR‐interacting RNA binding protein (RBP), mediated KEN‐induced ADAM10 translation in vitro and in vivo. SHMT2 controls AD signaling pathways through binding to a large number of RNAs and enhances the 5′UTR activity of ADAM10 by direct interaction with GAGGG motif, whereas this motif affected ribosomal scanning of eukaryotic initiation factor 2 (eIF2) in the 5′UTR. Together, KEN exhibits therapeutic potential for AD by linking OCM with RNA processing, in which the metabolic enzyme SHMT2 “moonlighted” as RBP by binding to GAGGG motif and promoting the 5′UTR‐dependent ADAM10 translation initiation.

To accurately evaluate the thermal hazards of cumene hydroperoxide (CHP) under heterogeneous temperature systems, a pressure vessel test device was employed to analyze the decomposition behavior of CHP in the heterogeneous temperature vessel. The influences of furnace temperature (200°C–300 °C) and sample mass (1 g–5 g) on the decomposition behavior were discussed respectively. The results show that in the 10 groups of experiments, CHP begins to accelerate autocatalytically after a long period of initiation step, with a rapid increase in temperature and pressure, and reach the maximum temperature and pressure rise rates in the later period. The maximum temperature and pressure are 248.39 °C and 324.1 kPa, and the maximum temperature and pressure rise rates reach 8.477 °C/s and 71.6 kPa/s, respectively. At a sample mass of 3 g, with the increase of furnace temperature, the maximum temperature and temperature rise rate increase, while both the maximum pressure and pressure rise rate are close; the thermal decomposition reaction time decreases exponentially, which obeys an equation of Δtd=2.592×107exp(−Te/18.051)+184.325(200°C≤Te≤300°C). At a furnace temperature of 300 °C, the maximum values of temperature, temperature rise rate, pressure, and pressure rise rate all increase with increasing sample mass.