Prevalence and associated factors of depressive and anxiety symptoms among Chinese secondary school students.

BACKGROUND: Depressive and anxiety symptoms affect about one-fourth of Chinese secondary school students. However, the prevalence and correlates of mental distress among secondary school students from Western China remain largely unexplored. This study aimed to examine the prevalence and associations of depressive and anxiety symptoms with demographic, family, school, life, and behavior factors in a large, representative sample of secondary school students in Zigong, a city in Western China. METHODS: Secondary school students were recruited using cluster sampling. The 9-item Patient Health Questionnaire, the 7-item Generalized Anxiety Disorder Questionnaire, Multidimensional Peer-Victimization Scale, the Pittsburgh Sleep Quality Index, and Nine-Item Internet Gaming Disorder Scale-Short Form were used. Descriptive statistic was used to describe the sociodemographic characteristics of participants. The clustering effect was adjusted by the "survey" package of R to calculate weighted prevalence. Univariate and multivariate logistic regression were used to explore associated factors of depression and anxiety, respectively. RESULTS: A total of 63,205 participants were involved, in which the weighted prevalence of depression in all subjects was 23.0% (95% CI: 19.6- 27.0%), and the weighted prevalence of anxiety was 13.9% (95% CI: 11.2- 17.0%). Logistic regression results showed girls, being single-child, non-nuclear family, peer bullying, sleep disturbance, and internet gaming disorder symptoms were positively associated with depressive and anxiety symptoms. CONCLUSION: Depressive and anxiety symptoms were prevalent among secondary school students in Western China. Our results can guide policy strategies for the assessment, prevention, and intervention of psychological status among Chinese secondary school students.

Function scores of different surgeries in the treatment of knee osteoarthritis: A PRISMA-compliant systematic review and network-meta analysis.

BACKGROUND: Osteoarthritis (OA) is the third most common diagnosis made by general practitioners in older patients. The aim of this study was to compare the function scores of different surgeries in the treatment of knee osteoarthritis (KOA). METHODS: Cohort studies about different surgical treatments for KOA were included with a comprehensive search in PubMed, Cochrane Library, and Embase. The standard mean difference (SMD) value was evaluated and the surface under the cumulative ranking (SUCRA) curve was drawn with a combination of direct and indirect evidence. A total of 265 eligible patients were enrolled and served as the nonoperative treatment group, osteotomy group, unicompartmental knee arthroplasty (UKA) group, total knee arthroplasty (TKA) group, and arthroscopic surgery group. Before surgery, 6 months after surgery, 1 year after surgery and 5 years after surgery, the hospital for special surgery (HSS) knee score, Lysholm score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and American knee society score (KSS) were recorded. RESULTS: A total of 9 cohort studies including 954 patients with KOA were finally enrolled into the study. The network-meta analysis revealed that osteotomy and UKA treatments showed a better efficacy on improving the function score. Our cohort study further confirmed that, a higher HSS knee score after 1 year and higher Lysholm score after 6 months and 1 year were observed in the osteotomy and UKA groups, while better HSS knee score and KSS after 6 months and 1 year were showed in the osteotomy and TKA groups. In the TKA group, Lysholm score and KSS were higher and WOMAC score was lower after 5 years than other groups. WOMAC score was lowest in the UKA group after 6 months, 1 year and 5 years of surgery. CONCLUSION: These results provide evidence that function scores of patients with KOA were improved by osteotomy, UKA, TKA, and arthroscopic surgery. And osteotomy and UKA showed better short-term efficacy, while TKA appeared better long-term efficacy.

Ultrafast Broadband Photodetectors Based on Three-Dimensional Dirac Semimetal Cd3As2.

Photodetection with extreme performances in terms of ultrafast response time, broad detection wavelength range, and high sensitivity has a wide range of optoelectronic and photonic applications, such as optical communications, interconnects, imaging, and remote sensing. Graphene, a typical two-dimensional Dirac semimetal, has shown excellent potential toward a high-performance photodetector with high operation speed, broadband response, and efficient carrier multiplications benefiting from its linear dispersion band structure with a high carrier mobility and zero bandgap. As the three-dimensional analogues of graphene, Dirac semimetal Cd3As2 processes all advantages of graphene as a photosensitive material but potentially has stronger interaction with light as a bulk material and thus enhanced responsivity. In this work, we report the realization of an ultrafast broadband photodetector based on Cd3As2. The prototype metal-Cd3As2-metal photodetector exhibits a responsivity of 5.9 mA/W with a response time of about 6.9 ps without any special device optimization. Broadband responses from 532 nm to 10.6 µm are achieved with a potential detection range extendable to far-infrared and terahertz. Systematical studies indicate that the photothermoelectric effect plays an important role in photocurrent generation. Our results suggest this emerging class of exotic quantum materials can be harnessed for photodetection with a high sensitivity and high speed (∼145 GHz) over a broad wavelength range.

Magnetotransport properties near the Dirac point of Dirac semimetal Cd3As2 nanowires.

Three-dimensional (3D) Dirac semimetals are featured by 3D linear energy-momentum dispersion relation, which have been proposed to be a desirable system to study Dirac fermions in 3D space and Weyl fermions in solid-state materials. Significantly, to reveal exotic transport properties of Dirac semimetals, the Fermi level should be close to the Dirac point, around which the linear dispersion is retained. Here we report the magnetotransport properties near the Dirac point in Cd3As2 nanowires, manifesting the evolution of band structure under magnetic field. Ambipolar field effect is observed with the Dirac point at V g = 3.9 V. Under high magnetic field, there is a resistivity dip in transfer curve at the Dirac point, which is caused by the Zeeman splitting enhanced density of state around the Dirac point. Furthermore, the low carrier density in the nanowires makes it feasible to enter into the quantum limit regime, resulting in the quantum linear magnetoresistance being observed even at room temperature. Besides, the dramatic reduction of bulk conductivity due to the low carrier density, together with a large surface to volume ratio of the nanowire, collectively help to reveal the Shubnikov-de Haas oscillations from the surface states. Our studies on transport properties around the Dirac point therefore provide deep insights into the emerging exotic physics of Dirac and Weyl fermions.

Two-Carrier Transport Induced Hall Anomaly and Large Tunable Magnetoresistance in Dirac Semimetal Cd3As2 Nanoplates.

Cd3As2 is a model material of Dirac semimetal with a linear dispersion relation along all three directions in the momentum space. The unique band structure of Cd3As2 is made with both Dirac and topological properties. It can be driven into a Weyl semimetal by symmetry breaking or a topological insulator by enhancing the spin-orbit coupling. Here we report the temperature and gate voltage-dependent magnetotransport properties of Cd3As2 nanoplates with Fermi level near the Dirac point. The Hall anomaly demonstrates the two-carrier transport accompanied by a transition from n-type to p-type conduction with decreasing temperature. The carrier-type transition is explained by considering the temperature-dependent spin-orbit coupling. The magnetoresistance exhibits a large nonsaturating value up to 2000% at high temperatures, which is ascribed to the electron-hole compensation in the system. Our results are valuable for understanding the experimental observations related to the two-carrier transport in Dirac/Weyl semimetals, such as Na3Bi, ZrTe5, TaAs, NbAs, and HfTe5.

A survey on occurrence of melamine and its analogues in tainted infant formula in China.

OBJECTIVE: To investigate the occurrence and concentrations of melamine and its analogues in tainted infant formula and to identify the etiologic factors for the urinary stones epidemic in infants and young children in China in 2008. METHODS: Sanlu infant formula samples were collected from families of the affected children in Gansu province, and markets in Gansu and Hebei provinces and Beijing city. Melamine and its analogues, including cyanuric acid, ammeline, and ammelide were measured by gas chromatography/tandem mass spectrometry. RESULTS: High prevalence and concentrations of melamine were found in Sanlu infant formula samples, with low concentrations of cyanuric acid, ammeline and ammelide. Melamine were detected in 87 out of 111 Sanlu infant formula samples with a range of 118 to 4,700 mg/kg. CONCLUSION: The results provide strong evidence for melamine as the etiological factor for the urinary stones epidemic in infants and young children in China in 2008.

[The relationship between lumbosacral transitional vertebra and the lumbar disc herniation].

OBJECTIVE: To investigate the relationship between lumbosacral transitional vertebra and the lumbar disc herniation (LDH). METHODS: The X-ray photographs of lumbar vertebra were retrospectively studied of patients with and without LDH confirmed by surgery, furthermore, the differential incidence of LDH between the two groups and the relationship between transitional vertebra and the position of disc herniation were statistically analyzed. RESULTS: The incidence of lumbosacral transitional vertebra was 18.3% in the control group, 52.7% in the LDH group, the difference was statistically significant. In the group with single lumbosacral transitional vertebra, there was 75.9% of LDH occurred on the same side of the transitional vertebra, 81.8% of which occurred at the upper one disc of the transitional vertebra; whereas 17.2% of LDH on the opposite side of the transitional vertebra, 80.0% of which occurred at the lower one disc of the transitional vertebra. CONCLUSIONS: There is a closer relationship between lumbosacral transitional vertebra and the LDH, and the lumbosacral transitional vertebra is one of the important factors in the emergence of LDH.