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Heavy metals persist in the sediment and can induce toxicological effects on living organisms. For analysing the risk of heavy metals, geochemical fractionation is beneficial. These geochemical fractions or speciations help to determine the heavy metals availability, mobility, toxicity, enrichment, and various risks. Here, we show how heavy metal contamination of sediment poses risks to both the ecosystem and human beings. We found significant Zn, Co and Cd contamination by analysing the geoaccumulation index. We also observed higher geoaccumulation index values for the pre-monsoon season than the post-monsoon one. Furthermore, pollution load index indicated gradual contamination of heavy metals in the sediments. This study's risk assessment and modified risk assessment codes showed low or no risk, but contamination factors indicated moderate to high risk. Our analysis of the effective range median mean quotient revealed some sampling stations as medium to high-priority sites. Similarly, probable effect level mean quotient designated some sampling stations as medium-low priority sites. We anticipated a moderate to significant mortality effect on the organisms from toxicity unit index values. Potential ecological risk index indicated a very high ecological risk on the Mahananda River. Furthermore, we predicted non-carcinogenic health hazards and carcinogenic health risks in the river's sediment. [ABSTRACT FROM AUTHOR]

Piezoelectric nanogenerators (PENGs) have been emerged as one of the most promising approach for harvesting energy from the movement of living system for low‐power electronic devices. Herein, a simple PENG and single‐electrode triboelectric nanogenerator (STENG) are reported that execute tremendous output performance. In zirconium oxide (ZrO2)/poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) nanocomposite polymer, ZrO2 acts as the nucleating agents for electroactive polymorph nucleation and also enhances the dielectric constant (≈23). Compared with previously reported PVDF‐HFP‐assisted prototype nanogenerators, this developed PENG exhibits excellent piezoelectric energy‐harvesting performance with very high power density, high energy conversion efficiency and high durability. The PENG exhibits a large value of open‐circuit voltage ≈120 V and short‐circuit current ≈1.95 μA under periodic finger imparting with high power density ≈7091 μW cm−3. Fabricated flexible PENG is capable to instantaneously light up commercially available 55 number of blue light emitting diode connected in parallel connection through bridge rectifier. High capacitor charging performance is also observed, such as 2.2 μF capacitor charged up to 3.5 V, in just 17 s time interval. Single‐electrode‐based TENG fabricated by this composite film also shows remarkable output voltage ≈7 V under finger touch. [ABSTRACT FROM AUTHOR]

A simple, lightweight, cost-effective, bio-compatible, and highly sensitive piezoelectric nanogenerator has been sketched in a sustainable manner using naturally available clay, i.e., kaolinite doped poly(vinylidene fluoride) film. The developed nanogenerator is able to produce electrical signals by capturing a very small mechanical signal of our living systems. Very low mechanical impulse due to human body vibration, air flow, and water wave has been well adsorbed by our fabricated piezoelectric nanogenerator to generate electrical output signals. The device generates output voltages (peak to peak) of ∼1.4 V, 325 mV, and 230 mV under human body vibration, air flow, and water wave, respectively. Moreover, under gentle finger impartation (force, ∼12.5 N), the device can generate an open circuit voltage of ∼45 V and a short circuit current of ∼2.9 μA. The results remain almost same for a long tested time duration (∼12 months). The power density is calculated to be 43.5 mW/cm3. A capacitor (∼1 μF) is charged up to ∼2.8 V within 18 s, and several LEDs are lightened using our device as an energy supplier. [ABSTRACT FROM AUTHOR]

Expeditious development of PENGs has been restricted several problems such as toxicity, high cost, and long-life. Herein, we report a biowaste crab shell-extracted chitin nanofiber (CNF) and CNF/poly(vinylidene fluoride) (PVDF)-based biocompatible, biodegradable, low cost, light weight, flexible, highly durable and efficient piezoelectric nanogenerators (PENGs) that enable harvesting of electrical energy from the mechanical energy of a living system. The pure CNF thin film-based piezoelectric nanogenerator (CPENG) shows excellent output performances (open circuit output voltage (Voc) = 22 V, short circuit current (Isc) = 0.12 μA) with a high piezoelectric coefficient, d33 = 9.49 pC N−1. The PENG based on CNF/PVDF (PCPEG) also shows very good output characteristics (Voc = 49 V and Isc = 1.9 μA). The incorporation of CNF in a PVDF matrix noticeably enhanced the electroactive β-phase nucleation, (F(β)) ∼ 81%, with a superior d33∼ 35.56 pC N−1. The PCPENG is able to charge a 2.2 μF capacitor to 3.6 V within a short time span (20 seconds) and illuminate 22 blue LEDs connected in series. Our as-fabricated PENGs could be suitable for long-life in vivo biomedical energy harvesting devices that can harvest energy from blood flow and heart beats and charge energy storage devices from mechanical energy such as body movements, moving cars, sea waves, air flow, and rain drops. [ABSTRACT FROM AUTHOR]

Ten Darjeeling tea clones (BT15/263, RR17/144, B777, T253, B157, Sundaram, HV39, AV2, K1/1 and TTV1) were collected from the experimental garden of Darjeeling Tea Research and Development Centre, Kurseong. Total phenol, flavonoids and two antioxidating enzymes (peroxidase and superoxide dismutase) were estimated. The total phenol ranged between 241 and 28 GAE mg g of leaf dry weight. The highest amount obtained in four clones, B15/263 (241.47), RR17/144 (221.2), B777 (154.54) and B157 (140.23 mg g). Flavonoids were estimated as Catechin equivalent (CE) and ranged between 56.88 and 20.81 CE mg g leaf dry weight. Higher amounts occurred in BT15/263 (56.88 mg g), B777 (56.69) and RR17/144 (48.63). Antioxidant activities were measured following DPPH and ABTS free radicle scavenging procedures and the results were well according to total polyphenol content among the clones (in total phenols, ranges of correlation in DPPH assay were r = 0.990-0.989, p ≤ 0.05; in flavonoids r = 0.954, p ≤ 0.01-0.987, p ≤ 0.05). Similarly, ABTS percent scavenging results were quiet significant. The IC values were determined for both DPPH and ABTS assay. PAGE expressions of isoforms in two antioxidative enzymes and quantification of them also varied much among the investigated clones. The incidence of total phenols, flavonoids, PRX and SOD and ROS scavenging assay in in-situ condition, might be used as biochemical markers towards the superior adaptability against abiotic stress. In the present work, four clones (B15/263, B777, RR17/144 and B157) would be designated as comparatively better suited to the predicted abiotic stress. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Development of fluorescent erbium doped hydroxyapatite (eHAp)-chitosan nanocomposite film. • Strong antimicrobial activity on bacterial cells. • Antimicrobial activity is primarily by electrostatic interaction with teichoic acid and polyelectrolytic complex formation. • Good biocompatible, fluorescent and biodegradable behavior in vitro. Abstract Development of fluorescent erbium doped hydroxyapatite (eHAp)-chitosan nanocomposite film is reported. Nanocrystalline eHAp has been synthesized by hydrothermal assisted precipitation method using erbium (III) ions as dopant. Physico-chemical characterization by UV/Visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminiscence spectroscopy (PL) and Field emission scanning electron microscopy(FESEM) confirmed incorporation and uniform distribution of eHAp in the chitosan films. Strong antimicrobial activity was observed using eHAp incorporated chitosan films against E. coli and S. aureus by contact inhibition on agar plates. On the other hand, excellent biocompatibility was observed with human lung fibroblast cells (WI-38) which showed strong attachment and proliferation on the chitosan films with minimal cytotoxicity. Moreover, the doped films showed good biodegradation and mineralization behavior after 2 weeks in simulated body fluid. Thus the doped fluorescent chitosan films with multifunctional attributes can be a strong candidate for diverse applications like in antimicrobial treatments, wound healing, tissue scaffolds and bioimaging. [ABSTRACT FROM AUTHOR]

Herein, biocompatible Ca 3 (PO 4 ) 2 nanorod-incorporated poly(vinylidene) difluoride films have been prepared via an in situ process. A good piezoelectricity ( d 33 ≈ 56.6 pC/N) along with a large dielectric constant of ∼3.48 × 10 5 at frequency 20 Hz has been achieved. Then, we have designed a biocompatible, highly durable, low-cost piezoelectric nanogenerator (CPNG) which shows the superiority in open-circuit voltage ∼47 V and current ∼1.8 μA generation with power density ∼47.4 mW cm -3 under the gentle touch of a finger. Excellent mechanical to electrical energy conversion efficiency (∼65.5%) of our developed CPNG leads to fast charging of a capacitor of 1 μF in 18 s and glowing of 26 light-emitting diodes (LEDs) under finger impartation. Further, a portable light-charging power pack (LCPP) has been developed using the high dielectric film as the storage function. Under light illumination, our LCPP generates open-circuit output voltage ∼1.29 V with short-circuit current 5.7 mA cm -2 . Areal capacitance ∼1779 F m -2 and storage efficiency ∼88% are achieved. The device is able to lighten up 22 LEDs for 10 days after charging once.

In the present work, we propose a simple and unique approach to design a lightweight, low-cost, self-charging power cell with considerable capacity to generate and store photocharges named self-charged photo-power cell (SCPPC). Initially, highly electroactive sodium dodecyl sulfate (SDS)-incorporated poly(vinylidene fluoride) (PVDF) composite thin films with a large dielectric constant of ∼525 are synthesized via a simplistic solution casting process. Then, the as-prepared high-dielectric SDS/PVDF thin film is used as a charge-storage medium in combination with an inorganic-organic dye film, i.e., ZnO nanoparticles-eosin Y-poly(vinylpyrrolidone) film, as a photoelectron generator in our SCPPC. An open-circuit voltage of ∼1.2 V is attained after charging SCPPC under illumination light with intensity ∼110 mW/cm 2 and then discharging fully with a constant current density of ∼4.5 mA/cm 2 . A specific areal capacitance of ∼450 F/m 2 is obtained with large energy and power densities of ∼90 mWh/m 2 and 54 W/m 2 , respectively. The improved overall efficiency, ∼3.78%, along with 89% storage efficiency leads to promising application possibilities of our rechargeable photo-power cell. The recyclability, i.e., rechargeability and storage durability, of the photo-power cell are also checked for 35 days without no such reduction in voltage generation and storage. Also, multicolored light-emitting diodes are lightened up using the photo-power cell as power source.

The design of an energy-harvesting unit with superior output characteristics, i.e., high power density, is a great technological challenge in the present time. Here, simple, lightweight, flexible, and cost-effective piezoelectric nanogenerators (PENGs) have been fabricated by integrating the aluminum electrodes onto Er 3+ /Fe 3+ stimulated electroactive, visible-light-emitting, and large dielectric PVDF films in which ErCl 3 ·6H 2 O and Fe(NO 3 ) 3 ·9H 2 O act as the catalytic agents for electroactive β polymorph nucleation and the enhancement of dielectric properties. The developed PENGs exhibit excellent energy-harvesting performance with very high power density and very fast charging ability compared with the previously reported PVDF-assisted prototype nanogenerators. The PENGs lead to very large power density (∼160 and ∼55.34 mW cm -3 ) under periodic finger imparting for Er 3+ - and Fe 3+ -stimulated PVDF-film-based energy-harvester units, respectively. The fabricated self-powered PENG is also able to light up 54 commercially available light-emitting diodes.