Triboelectric Nanogenerator-Based Near-Field Electrospinning System for Optimizing PVDF Fibers with High Piezoelectric Performance.

Electrospinning is an effective method to prepare polyvinylidene fluoride (PVDF) piezoelectric fibers with a high-percentage ß phase. However, as an energy conversion material for micro- and nanoscale diameters, PVDF fibers have not been widely used due to their disordered arrangement prepared by traditional electrospinning. Here, we designed a near-field electro-spinning (NFES) system driven by a triboelectric nanogenerator (TENG) to prepare PVDF fibers. The effects of five important parameters (PVDF concentration, needle inner diameter, TENG pulse DC voltage (TPD-voltage), flow rate, and drum speed) on the ß phase fraction of PVDF fiber were optimized one by one. The results showed that the electrospun PVDF fibers had uniform diameter and controllable parallel arrangement. The ß phase content of the optimized PVDF fiber reached 91.87 ± 0.61%. For the bending test of a single PVDF fiber piezoelectric device, when the strain is 0.098%, the electric energy of the single PVDF fiber device of NFES reaches 7.74 pJ and the energy conversion efficiency reaches 13.5%, which is comparable to the fibers prepared by the commercial power-driven NFES system. In 0.5 Hz, the best matching load resistance of a PVDF single fiber device is 10.6 MΩ, the voltage is 6.1 mV, and the maximum power is 3.52 pW. Considering that TENG can harvest micromechanical energy in the low frequency environment, the application scenario of the NFES system can be extended to the wild or remote mountainous areas without traditional high-voltage power supply. Therefore, the electrospun PVDF fibers in this system will have potential applications in high-precision 3D fabrication, self-powered sensors, and flexible wearable electronic products.

Effects of vitamin D supplementation during pregnancy on bone health and offspring growth: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Whether vitamin D supplementation during pregnancy is beneficial to bone health and offspring growth remains controversial. Moreover, there is no universal agreement regarding the appropriate dose and the time of commencement of vitamin D supplementation during pregnancy. OBJECTIVE: We aimed to systematically review the effects of vitamin D supplementation during pregnancy on bone development and offspring growth. METHODS: A literature search for randomized controlled trials (RCTs) was performed in 7 electronic databases to identify relevant studies about the effects of vitamin D supplementation during pregnancy on bone development and offspring growth from inception to May 22, 2022. A Cochrane Risk Assessment Tool was used for quality assessment. Vitamin D supplementation was compared with placebo or standard supplements. The effects are presented as the mean differences (MDs) with 95% CIs. The outcomes include bone mineral content (BMC), bone mineral density (BMD), bone area (BA), femur length (FL) and humeral length (HL); measurement indicators of growth, including length, weight and head circumference; and secondary outcome measures, including biochemical indicators of bone health, such as the serum 25(OH)D concentration. Additionally, subgroup analyses were carried out to evaluate the impact of different doses and different initiation times of supplementation with vitamin D. RESULTS: Twenty-three studies with 5390 participants met our inclusion criteria. Vitamin D supplementation during pregnancy was associated with increased humeral length (HL) (MD 0.13, 95% CI 0.06, 0.21, I2 = 0, P = 0.0007) during the fetal period (third trimester). Vitamin D supplementation during pregnancy was associated with a significantly increased length at birth (MD 0.14, 95% CI 0.04, 0.24, I2 = 24%, P = 0.005) and was associated with a higher cord blood 25(OH)D concentration (MD 48.74, 95% CI 8.47, 89.01, I2 = 100%, P = 0.02). Additionally, subgroup analysis revealed that birth length was significantly higher in the vitamin D intervention groups of ≤1000 IU/day and ≥4001 IU/day compared with the control group. Prenatal (third trimester) vitamin D supplementation was associated with a significant increase in birth length, while prenatal (second trimester) vitamin D supplementation was associated with a significant increase in birth weight. CONCLUSION: Vitamin D supplementation during pregnancy may be associated with increased humeral length (HL) in the uterus, increased body length at birth and higher cord blood 25(OH)D concentration. Evidence of its effect on long-term growth in children is lacking. Additional rigorous high-quality, long-term and larger randomized trials are required to more fully investigate the effects of vitamin D supplementation during pregnancy.

Self-powered droplet manipulation system for microfluidics based on triboelectric nanogenerator harvesting rotary energy.

Microfluidic technology, as a method for manipulating tiny fluids, has the advantages of low sample consumption, fast reaction, and no cross-contamination. In a microfluidic system, accurate manipulation of droplets is a crucial technology that has been widely investigated. In this work, a self-powered droplet manipulation system (SDMS) is proposed to realize various droplet operations, including moving, splitting, merging, mixing, transporting chemicals and reacting. The SDMS is mainly composed of a triboelectric nanogenerator (TENG), an electric brush, and a microfluidic device. The TENG serves as a high-voltage source to power the system. Using different electric brushes and microfluidic devices, different manipulations of droplets can be achieved. Moreover, by experiments and simulations, the influence of the electrode width, the electrode gap and the central angle of one electrode on the performance of SDMS is analyzed in detail. Firstly, by using electrowetting-on-dielectric (EWOD) technology, SDMS can accurately control droplets for long-distance linear movement and simultaneously control multiple droplets to move in a circular electrode track consisting of 40 electrodes. SDMS can also manipulate two droplets of different components to merge and react. In addition, using dielectrophoresis (DEP) technology, SDMS can separate droplets with maximum volumes of 400 µL and reduce the time of the complete mixing of two droplets with different components by 6.3 times compared with the passive mixing method. Finally, the demonstration shows that a droplet can be manipulated by hand power for chemical delivery and chemical reactions on a circular electrode track without an external power source, which proves the applicability of SDMS as an open-surface microfluidic device. Therefore, the self-powered droplet manipulation system proposed in this work may have great application in the fields of drug delivery, micro chemical reactions, and biological microanalysis.

Ovary and uterus related adverse events associated with statin use: an analysis of the FDA Adverse Event Reporting System.

Experimental studies have demonstrated statin-induced toxicity for ovary and uterus. However, the safety of statins on the functions of ovary and uterus in real-world clinical settings remains unknown. The aim of this study was to identify ovary and uterus related adverse events (AEs) associated with statin use by analyzing data from FDA Adverse Event Reporting System (FAERS). We used OpenVigil 2.1 to query FAERS database. Ovary and uterus related AEs were defined by 383 Preferred Terms, which could be classified into ten aspects. Disproportionality analysis was performed to assess the association between AEs and statin use. Our results suggest that statin use may be associated with a series of ovary and uterus related AEs. These AEs are involved in ovarian cysts and neoplasms, uterine neoplasms, cervix neoplasms, uterine disorders (excl neoplasms), cervix disorders (excl neoplasms), endocrine disorders of gonadal function, menstrual cycle and uterine bleeding disorders, menopause related conditions, and sexual function disorders. Moreover, there are variabilities in the types and signal strengths of ovary and uterus related AEs across individual statins. According to our findings, the potential ovary and uterus related AEs of statins should attract enough attention and be closely monitored in future clinical practice.