[Rheology and in vitro release properties of thermosensitive in situ gel of Yihuang Decoction and its common gel for vaginal use].

To evaluate the traits and rheological properties of thermosensitive in situ gel of Yihuang Decoction and its common gel for vaginal use, and predict the release behavior of Yihuang Decoction in situ gel in vitro. Poloxamer was used as thermosensitive material to prepare Yihuang Decoction vaginal in situ gel, and Yihuang Decoction common gel was prepared with carbopol. Then the differences of the two gels before and after diluting with vaginal fluid were compared. The rheological parameters of Yihuang Decoction in situ gel and its common gel were determined with Anton Paar MCR102 rheometer. In addition, berberine hydrochloride was selected as an index component to evaluate the in vitro release properties of Yihuang Decoction vaginal thermosensitive in situ gel. Yihuang Decoction vaginal thermosensitive in situ gel was Newtonian fluid under low-temperature conditions, which was yellow and transparent. After reaching the gelling temperature of 24.5 ℃, it became semi-solid, pseudoplastic fluid. The gelling temperature was predicted to be 37 ℃, and the phase transition time was 30 s after diluting with simulated vaginal fluid. However, the rheological properties of Yihuang Decoction common gel had no significant changes with temperature. Compared with in situ gel, the color of common gel was darker and more translucent. Besides, its mobility was stronger after diluting with simulated vaginal fluid. The in vitro release study showed that the kinetic behavior of berberine hydrochloride in Yihuang Decoction vaginal thermosensitive in situ gel was matched with the Higuchi equation. Through simulation of vaginal administration, physical properties and dynamic rheological parameters were used to intuitively and scientifically evaluate the two gels. Compared with the common gel, the thermosensitive in situ gel could quickly attached to the vaginal mucosa and release drug, and thus was more suitable for developing vaginal administration of Yihuang Decoction, which also provides references for studying new vaginal preparation of Yihuang Decoction.

Sliding-triboelectric nanogenerators based on in-plane charge-separation mechanism.

Aiming at harvesting ambient mechanical energy for self-powered systems, triboelectric nanogenerators (TENGs) have been recently developed as a highly efficient, cost-effective and robust approach to generate electricity from mechanical movements and vibrations on the basis of the coupling between triboelectrification and electrostatic induction. However, all of the previously demonstrated TENGs are based on vertical separation of triboelectric-charged planes, which requires sophisticated device structures to ensure enough resilience for the charge separation, otherwise there is no output current. In this paper, we demonstrated a newly designed TENG based on an in-plane charge separation process using the relative sliding between two contacting surfaces. Using Polyamide 6,6 (Nylon) and polytetrafluoroethylene (PTFE) films with surface etched nanowires, the two polymers at the opposite ends of the triboelectric series, the newly invented TENG produces an open-circuit voltage up to ~1300 V and a short-circuit current density of 4.1 mA/m(2) with a peak power density of 5.3 W/m(2), which can be used as a direct power source for instantaneously driving hundreds of serially connected light-emitting diodes (LEDs). The working principle and the relationships between electrical outputs and the sliding motion are fully elaborated and systematically studied, providing a new mode of TENGs with diverse applications. Compared to the existing vertical-touching based TENGs, this planar-sliding TENG has a high efficiency, easy fabrication, and suitability for many types of mechanical triggering. Furthermore, with the relationship between the electrical output and the sliding motion being calibrated, the sliding-based TENG could potentially be used as a self-powered displacement/speed/acceleration sensor.

Surface-functionalized hyperbranched poly(amido acid) magnetic nanocarriers for covalent immobilization of a bacterial γ-glutamyltranspeptidase.

In this study, we synthesized water-soluble hyperbranched poly(amido acid)s (HBPAAs) featuring multiple terminal CO2H units and internal tertiary amino and amido moieties and then used them in conjunction with an in situ Fe2+/Fe3+ co-precipitation process to prepare organic/magnetic nanocarriers comprising uniformly small magnetic iron oxide nanoparticles (NP) incorporated within the globular HBPAAs. Transmission electron microscopy revealed that the HBPAA-γ-Fe2O3 NPs had dimensions of 6-11 nm, significantly smaller than those of the pristine γ-Fe2O3 (20-30 nm). Subsequently, we covalently immobilized a bacterial γ-glutamyltranspeptidase (BlGGT) upon the HBPAA-γ-Fe2O3 nanocarriers through the formation of amide linkages in the presence of a coupling agent. Magnetization curves of the HBPAA-γ-Fe2O3/BlGGT composites measured at 300 K suggested superparamagnetic characteristics, with a saturation magnetization of 52 emu g⁻¹. The loading capacity of BlGGT on the HBPAA-γ-Fe2O3 nanocarriers was 16 mg g⁻¹ support; this sample provided a 48% recovery of the initial activity. The immobilized enzyme could be recycled 10 times with 32% retention of the initial activity; it had stability comparable with that of the free enzyme during a storage period of 63 days. The covalent immobilization and stability of the enzyme and the magnetization provided by the HBPAA-γ-Fe2O3 NPs suggests that this approach could be an economical means of depositing bioactive enzymes upon nanocarriers for BlGGT-mediated bio-catalysis.

Anodic TiO2 nanotubular arrays with pre-synthesized hydroxyapatite--an effective approach to enhance the biocompatibility of titanium.

Electrochemically anodized TiO2 nanotubular arrays can provide large surface areas for biological species attachment. In order to further enhance the biocompatibility of Ti medical implants, we deposited a pre-synthesized hydroxyapatite inside and on the nanotubular arrays, and examined the biocompatibility of the anodized TiO2 nanotubular arrays with pre-synthesized hydroxyapatite by in vitro assessment in simulated body fluid, and in vitro cell culture. The results showed that the hydroxyapatite coating was able to be induced on TiO2 nanotubular arrays with pre-synthesized hydroxyapatite within 5 days while only a thin film composed of calcium phosphorous chemicals formed on as-formed TiO2 nanotubular arrays. The cell culture evaluation further proved the enhancement of cell attachment and proliferation on TiO2 nanotubular arrays with pre-synthesized hydroxyapatite as opposed to those without pre-synthesized hydroxyapatite. The present study proves that formation of TiO2 nanotubular arrays with pre-synthesized hydroxyapatite a promising method to enhance the biocompatibility of Ti implants.

Nanoscale triboelectric-effect-enabled energy conversion for sustainably powering portable electronics.

Harvesting energy from our living environment is an effective approach for sustainable, maintenance-free, and green power source for wireless, portable, or implanted electronics. Mechanical energy scavenging based on triboelectric effect has been proven to be simple, cost-effective, and robust. However, its output is still insufficient for sustainably driving electronic devices/systems. Here, we demonstrated a rationally designed arch-shaped triboelectric nanogenerator (TENG) by utilizing the contact electrification between a polymer thin film and a metal thin foil. The working mechanism of the TENG was studied by finite element simulation. The output voltage, current density, and energy volume density reached 230 V, 15.5 µA/cm(2), and 128 mW/cm(3), respectively, and an energy conversion efficiency as high as 10-39% has been demonstrated. The TENG was systematically studied and demonstrated as a sustainable power source that can not only drive instantaneous operation of light-emitting diodes (LEDs) but also charge a lithium ion battery as a regulated power module for powering a wireless sensor system and a commercial cell phone, which is the first demonstration of the nanogenerator for driving personal mobile electronics, opening the chapter of impacting general people's life by nanogenerators.

Transparent triboelectric nanogenerators and self-powered pressure sensors based on micropatterned plastic films.

Transparent, flexible and high efficient power sources are important components of organic electronic and optoelectronic devices. In this work, based on the principle of the previously demonstrated triboelectric generator, we demonstrate a new high-output, flexible and transparent nanogenerator by using transparent polymer materials. We have fabricated three types of regular and uniform polymer patterned arrays (line, cube, and pyramid) to improve the efficiency of the nanogenerator. The power generation of the pyramid-featured device far surpassed that exhibited by the unstructured films and gave an output voltage of up to 18 V at a current density of ∼0.13 µA/cm(2). Furthermore, the as-prepared nanogenerator can be applied as a self-powered pressure sensor for sensing a water droplet (8 mg, ∼3.6 Pa in contact pressure) and a falling feather (20 mg, ∼0.4 Pa in contact pressure) with a low-end detection limit of ∼13 mPa.

Wireless, battery-free, multifunctional integrated bioelectronics for respiratory pathogens monitoring and severity evaluation.

The rapid diagnosis of respiratory virus infection through breath and blow remains challenging. Here we develop a wireless, battery-free, multifunctional pathogenic infection diagnosis system (PIDS) for diagnosing SARS-CoV-2 infection and symptom severity by blow and breath within 110 s and 350 s, respectively. The accuracies reach to 100% and 92% for evaluating the infection and symptom severity of 42 participants, respectively. PIDS realizes simultaneous gaseous sample collection, biomarker identification, abnormal physical signs recording and machine learning analysis. We transform PIDS into other miniaturized wearable or portable electronic platforms that may widen the diagnostic modes at home, outdoors and public places. Collectively, we demonstrate a general-purpose technology for rapidly diagnosing respiratory pathogenic infection by breath and blow, alleviating the technical bottleneck of saliva and nasopharyngeal secretions. PIDS may serve as a complementary diagnostic tool for other point-of-care techniques and guide the symptomatic treatment of viral infections.

Self-powered system with wireless data transmission.

We demonstrate the first self-powered system driven by a nanogenerator (NG) that works wirelessly and independently for long-distance data transmission. The NG was made of a free cantilever beam that consisted of a five-layer structure: a flexible polymer substrate, ZnO nanowire textured films on its top and bottom surfaces, and electrodes on the surfaces. When it was strained to 0.12% at a strain rate of 3.56% S(-1), the measured output voltage reached 10 V, and the output current exceeded 0.6 µA (corresponding power density 10 mW/cm(3)). A system was built up by integrating a NG, rectification circuit, capacitor for energy storage, sensor, and RF data transmitter. Wireless signals sent out by the system were detected by a commercial radio at a distance of 5-10 m. This study proves the feasibility of using ZnO nanowire NGs for building self-powered systems, and its potential application in wireless biosensing, environmental/infrastructure monitoring, sensor networks, personal electronics, and even national security.

Microplastic pollution in wild commercial nekton from the South China Sea and Indian Ocean, and its implication to human health.

Marine biota, especially commercially important species, serves as a basis for human nutrition. However, millions of tons of plastic litter are produced and enter the marine environment every year, with potential adverse impacts on marine organisms. In the present study, we investigated the occurrence and characteristics of microplastic (MP) pollution in the digestive tracts of 13 species of wild nektons from 20 stations sampled in the South China Sea (SCS) and the Indian Ocean (IO), and assessed the human health risks of MPs. The detection rate of MPs ranged from 0.00% to 50.00% from the SCS, which was dramatically lower than that from the IO (10.00-80.00%). The average abundance of MP was 0.18 ± 0.06 items g wet weight-1 (ww-1) in the SCS, which was significantly lower than that in the IO with a concentration of 0.70 ± 0.16 items g ww-1. Most MPs were fibers in type, black in color, and polyester (PES) in polymer composition in both the SCS and IO. Interestingly, distinct profiles of MP pollution were found between the benthic and pelagic nektons: 1) The predominant MP composition was PES in the benthic nektons, whereas polyamide (PA) accounted for a larger part of the total MP count in the pelagic nektons within the SCS; 2) The abundance of MP in the benthic nektons (0.52 ± 0.24 items individual-1) was higher than that in the pelagic nektons (0.30 ± 0.11 items individual-1). Accordingly, the mean hazard score of MPs detected in the benthic nektons (220.66 ± 210.75) was higher than that in the pelagic nektons (49.53 ± 22.87); 3) The mean size of the MP in the pelagic nektons (0.84 ± 0.17 mm) was larger than that in the benthic nektons (0.49 ± 0.09 mm). Our findings highlight the need to further investigate the ecological impacts of MPs on wild nekton, especially commercially important species, and its potential implications for human health.

Topical Delivery of Four Neuroprotective Ingredients by Ethosome-Gel: Synergistic Combination for Treatment of Oxaliplatin-Induced Peripheral Neuropathy.

BACKGROUND: Peripheral neuropathy is a common and painful side effect that occurs in patients with cancer induced by Oxaliplatin (OXL). The neurotoxicity correlates with the damage of dorsal root ganglion (DRG) neurons and Schwann cells (SCs). Hydroxysafflor yellow A (HSYA), icariin, epimedin B and 3, 4-dihydroxybenzoic acid (DA) are the main neuroprotective ingredients identified in Wen-Luo-Tong (WLT), a traditional Chinese medicinal topical compound. The purpose of this study was to prepare and evaluate the efficacy of an ethosomes gel formulation loaded with a combination of HSYA, icariin, epimedin B and DA. However, the low LogP value, poor solubility and macromolecule are several challenges for topical delivery of these drugs. METHODS: Ethosomes were prepared by the single-step injection technique. Particle size, entrapment efficiency and in vitro drug deposition studies were determined to select the optimum ethosomes. The optimized ethosomes were further incorporated into carbopol to obtain a gel. The rheological properties, morphology, in vitro drug release, in vitro gel application and skin distribution of the ethosomes gels were studied. A rat model of oxaliplatin-induced neuropathy was established to assess the therapeutic efficacy of the ethosomes gel. RESULTS: Seventy percent (v/v) ethanol, cinnamaldehyde and Phospholipon 90G were employed to develop ethosomes a carrier system. This system had a high entrapment efficiency, carried large amounts of HSYA, epimedin B, DA and icarrin, and penetrated deep into the epidermis and dermis. The optimized ethosomes had the maximum deposition of icariin, HSYA, epimedin B and relative higher amount of DA in epidermis (2.00±0.13 µg/cm2, 5.72±0.75 µg/cm2, 1.97±0.27 µg/cm2 and 9.25±1.21 µg/cm2, respectively). 0.5% carbopol 980 was selected to develop the ethosomes gel with desirable viscoelasticity and spreadability, which was suitable for topical application. The mechanical allodynia and hyperalgesia induced by OXL in rats were significantly reduced after the new ethosomes gel was applied to rats compared to model group. CONCLUSION: Based on our findings, the ethosomes gel delivery system provided a new formulation for the topical delivery of HSYA, icariin, epimedin B and DA to counteract OXL-induced peripheral neuropathy.

In situ forming gelatin/hyaluronic acid hydrogel for tissue sealing and hemostasis.

Fibrin glue has been widely used as a surgical sealing and hemostatic agent. Its application is restricted due to poor tissue adhesion and low mechanical strength. To develop better tissue sealant and hemostatic agent, this study prepared the injectable hydrogels by chemically cross-linking gelatin (G) with or without hyaluronic acid (HA) in situ at a mild condition. The rheological analysis, Fourier transform infrared spectroscopy, swelling, proteolytic degradation, biocompatibility, tissue sealing, and hemostatic ability of the hydrogels were investigated. It was found that the chemical cross-linking rapidly formed in both self-crosslinking gelatin (sc-G) and gelatin/hyaluronate acid (G/HA) hydrogels. The hydrogels could be degraded by trypsin and had a desirable biocompatibility. The tissue sealing ability of the hydrogels was superior to fibrin glue. Furthermore, the G/HA hydrogel had similar hemostatic performance as fibrin glue, and was better than that of gelatin hydrogel. The results in the study indicated that the G/HA hydrogel could be used in clinic as a tissue sealant or surgical hemostat.

Atmospheric dry deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans in the vicinity of municipal solid waste incinerators.

This study focuses on the atmospheric dry deposition flux of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the vicinity of the two municipal solid waste incinerators (MSWIs) located in southern Taiwan. PCDD/Fs in ambient air were taken and analyzed for seventeen 2,3,7,8-substituted PCDD/Fs during November 2004 and July 2005. Results show that the mean concentrations of PCDD/Fs in the ambient air near MSWI-GS and MSWI-RW were 0.090 and 0.097pg I-TEQ/Nm(3), respectively. Dry deposition fluxes of total PCDD/Fs were 18.0 and 23.5pg I-TEQ/(m(2)d) in the ambient air near MSWI-GS and MSWI-RW, respectively, which were considerably higher than that measured in Guangzhou, China. Annual dry deposition fluxes of total PCDD/Fs in the ambient air near MSWI-GS and MSWI-RW were 189 and 217ng/(m(2)year), respectively, which were also much higher than dry deposition of total PCDD/Fs to the Atlantic Ocean. The results of the present study strongly suggest that exposure to PCDD/Fs in this area should be reduced. In addition, parametric sensitivity shows that dry deposition flux of PCDD/Fs is most sensitive to dry deposition velocity of the particle-phase, followed by air temperature and concentration of total suspended particulate but least sensitive to dry deposition velocity of the gas-phase.

In situ injectable hyaluronic acid/gelatin hydrogel for hemorrhage control.

Tissue sealants are used for hemorrhage control which is imperative in many surgical procedures. It is a highly challenging task to obtain the ideal tissue sealant. Only a few commercially tissue sealants are available to be used for internal tissue or organ hemorrhage control. This study introduced two in situ injectable hydrogels for hemorrhage control: self-crosslinking gelatin (sc-G) hydrogel and hyaluronic acid/gelatin (HA/G) hydrogel. They were prepared on the tissue surface in situ and characterized by rheological analysis, stability, cytotoxicity, and bursting strength test. The hemostatic ability of the hydrogels was evaluated in a liver-bleeding rat model. The sc-G and HA/G hydrogels gelled around 90 s and 50 s, respectively. They were preferable for cell attachment and proliferation. The bursting strengths of both hydrogels exceeded that of fibrin glue. The hemostatic ability of HA/G hydrogel was better than that of sc-G hydrogel, and was same as that of fibrin glue. The HA/G hydrogel could be used as a tissue sealant for hemorrhage control in clinic.

Evaluation of surgical anti-adhesion products to reduce postsurgical intra-abdominal adhesion formation in a rat model.

BACKGROUND: Adhesions frequently occur after abdominal surgery. Many anti-adhesion products have been used in clinic. However, the evidences are short for surgeons to reasonably choose the suitable anti-adhesion produces in clinical practice. This study provided such evidence by comparing the efficiency of five products to prevent abdominal adhesion formation in a rat model. METHODS: Fifty-six Sprague-Dawley rats were randomly divided into seven groups: sham-operation group, adhesion group, and five product groups (n = 8). The abdomens of rats were opened. The injuries were created on abdominal wall and cecum in the adhesion and product groups. The wounds on abdominal wall and cecum of rats in the adhesion group were not treated before the abdomens were closed. The wounds on abdominal wall and cecum of rats in the product groups were covered with anti-adhesion product: polylactic acid (PLA) film, Seprafilm®, medical polyethylene glycol berberine liquid (PEG), medical sodium hyaluronate gel (HA), or medical chitosan (Chitosan). Fourteen days after surgery, the adhesions were evaluated by incidence, severity, adhesion area on abdominal wall and adhesion breaking strength. RESULTS: The application of PLA film and Seprafilm® significantly reduced the incidence, severity, adhesion area and breaking strength of cecum-abdomen adhesion (P<0.05). HA, PEG and Chitosan failed to significantly reduce the cecum-abdomen adhesion (P>0.05). The statistical significances in the incidence and severity of abdomen-adipose adhesion between adhesion group and the product groups were not achieved. However, Seprafilm® was more effective to reduce abdomen-adipose adhesion than PLA film. Furthermore, it was found that the products tested in this study did not effectively reduce cecum-adipose adhesion. The application of PEG could result in abdomen-small intestine adhesion. CONCLUSION: Based on the results of this study, the preference order of anti-adhesion products used to reduce postsurgical intra-abdominal adhesion formation is Seprafilm > PLA >> HA > Chitosan > PEG.

Body burdens of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls and their relations to estrogen metabolism in pregnant women.

Polychlorinated dibenzo-p-dioxins (PCDDs, dioxins), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) are environmental endocrine disruptors that have half-lives of 7-10 years in the human body and have toxicities that probably include carcinogenesis. A high ratio of 4-hydroxyl estradiol (4-OH-E2) to 2-hydroxyl estradiol (2-OH-E2) has been suggested as a potential biomarker for estrogen-dependent neoplasms. In this cohort study of maternal-fetal pairs, we examined the relationship of PCDD/PCDF and PCB exposure to levels of estrogen metabolites in the sera of 50 pregnant women 25-34 years of age from central Taiwan. Maternal blood was collected during the third trimester, and the placenta was collected at delivery. We measured 17 dioxin congeners, 12 dioxin-like PCBs, and 6 indicator PCBs in placenta using gas chromatography coupled with high-resolution mass spectrometry. Estrogen metabolites in maternal serum were analyzed by liquid chromatography tandem mass spectrometry. The ratio of 4-OH-E2:2-OH-E2 decreased with increasing exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (beta=-0.124, p=0.004 by the general linear regression model, R=0.4). Meanwhile, serum levels of 4-OH-E2 increased with increasing concentrations of high-chlorinated PCDFs (i.e., 1,2,3,4,6,7,8-hepta-CDF: beta=0.454, p=0.03, R=0.30). Altered estrogen catabolism might be associated with body burdens of PCDDs/PCDFs. Our study suggests that exposure to PCDDs/PCDFs significantly affects estrogen metabolism. Therefore, PCDD/PCDF exposure must be considered when using the OH-E2 ratio as a breast cancer marker.

Kinetics and mechanisms of cholesterol esterase inhibition by cardiovascular drugs in vitro.

Cardiovascular drugs such as lovastatin, simvastatin, amlodipine besylate, nifedipine, and hydralazine hydrochloride inhibit cholesterol esterase (CEase) in vitro. In the present paper, an attempt was made to determine kinetically the reaction mechanism for CEase inhibition by these drugs. The inhibition constant, Ki, for the mixed-type inhibition of CEase by these drugs in the presence of triton-X-100 or taurochloate were measured. Moreover, the pKi values were correlated with the molecular weights of these drugs. In conclusion, the fact that these drugs lower cholesterol levels in the plasma low-density lipoprotein may be partially due to the CEase inhibition by these drugs.

Effect of carbodiimide-derivatized hyaluronic acid gelatin on preventing postsurgical intra-abdominal adhesion formation and promoting healing in a rat model.

Adhesions often occur after abdominal surgery. It could cause chronic pelvic pain, intestinal obstruction, and infertility. A hydrogel biomaterial, carbodiimide-derivatized hyaluronic acid gelatin (cd-HA gelatin), has been successfully used to reduce adhesion formation after flexor tendon grafting. This study investigated the efficacy of cd-HA gelatin in preventing postsurgical peritoneal adhesions in a rat model. The surgical traumas were created on the underlying muscle of the abdominal wall and the serosal layer of the cecum. The wounds were covered with or without cd-HA gelatin. Animals were euthanized at day 14 after surgery. Adhesion formation was assessed with adhesion degree and adhesion breaking strength. The healing of abdominal wall was evaluated with biomechanical testing and histological analysis. The adhesions occurred in all rats (n = 12) without cd-HA gelatin treatment. The application of cd-HA gelatin significantly reduced the adhesion rate from 100% to 58%. The decrease of adhesion breaking strength also manifested that cd-HA gelatin could reduce postsurgical intra-abdominal adhesion formation. Moreover, it was found that cd-HA gelatin was a safe material and could promote tissue healing. The cd-HA gelatin hydrogel could reduce the formation of intra-abdominal adhesions without adversely effects on wound healing.

A highly shape-adaptive, stretchable design based on conductive liquid for energy harvesting and self-powered biomechanical monitoring.

The rapid growth of deformable and stretchable electronics calls for a deformable and stretchable power source. We report a scalable approach for energy harvesters and self-powered sensors that can be highly deformable and stretchable. With conductive liquid contained in a polymer cover, a shape-adaptive triboelectric nanogenerator (saTENG) unit can effectively harvest energy in various working modes. The saTENG can maintain its performance under a strain of as large as 300%. The saTENG is so flexible that it can be conformed to any three-dimensional and curvilinear surface. We demonstrate applications of the saTENG as a wearable power source and self-powered sensor to monitor biomechanical motion. A bracelet-like saTENG worn on the wrist can light up more than 80 light-emitting diodes. Owing to the highly scalable manufacturing process, the saTENG can be easily applied for large-area energy harvesting. In addition, the saTENG can be extended to extract energy from mechanical motion using flowing water as the electrode. This approach provides a new prospect for deformable and stretchable power sources, as well as self-powered sensors, and has potential applications in various areas such as robotics, biomechanics, physiology, kinesiology, and entertainment.

Freestanding triboelectric-layer-based nanogenerators for harvesting energy from a moving object or human motion in contact and non-contact modes.

For versatile mechanical energy harvesting from arbitrary moving objects such as humans, a new mode of triboelectric nanogenerator is developed based on the sliding of a freestanding triboelectric-layer between two stationary electrodes on the same plane. With two electrodes alternatively approached by the tribo-charges on the sliding layer, electricity is effectively generated due to electrostatic induction. A unique feature of this nanogenerator is that it can operate in non-contact sliding mode, which greatly increases the lifetime and the efficiency of such devices.

Genetic structure and demographic history should inform conservation: Chinese cobras currently treated as homogenous show population divergence.

An understanding of population structure and genetic diversity is crucial for wildlife conservation and for determining the integrity of wildlife populations. The vulnerable Chinese cobra (Naja atra) has a distribution from the mouth of the Yangtze River down to northern Vietnam and Laos, within which several large mountain ranges and water bodies may influence population structure. We combined 12 microsatellite loci and 1117 bp of the mitochondrial cytochrome b gene to explore genetic structure and demographic history in this species, using 269 individuals from various localities in Mainland China and Vietnam. High levels of genetic variation were identified for both mtDNA and microsatellites. mtDNA data revealed two main (Vietnam + southern China + southwestern China; eastern + southeastern China) and one minor (comprising only two individuals from the westernmost site) clades. Microsatellite data divided the eastern + southeastern China clade further into two genetic clusters, which include individuals from the eastern and southeastern regions, respectively. The Luoxiao and Nanling Mountains may be important barriers affecting the diversification of lineages. In the haplotype network of cytchrome b, many haplotypes were represented within a "star" cluster and this and other tests suggest recent expansion. However, microsatellite analyses did not yield strong evidence for a recent bottleneck for any population or genetic cluster. The three main clusters identified here should be considered as independent management units for conservation purposes. The release of Chinese cobras into the wild should cease unless their origin can be determined, and this will avoid problems arising from unnatural homogenization.