High-Performance Flexible Piezoelectric Nanogenerator Assisted by a Three-phase PVDF/WS2/rGO Nanocomposite.

The emergence of piezoelectric nanogenerators presents a promising alternative to supply energy demands within the realms of portable and miniaturized devices. In this article, the role of 2D transition metal dichalcogenide (TMD) tungsten sulfide (WS2) and conductive rGO sheets as filler materials inside the polyvinylidene fluoride (PVDF) matrix on piezoelectric performances has been investigated extensively. The strong electrostatic interaction between C-F and C-H monomer bonds of PVDF interacted with the large surface area of the WS2 nanosheets, increasing the electroactive polar phases and resulting in enhanced ferroelectricity in the PVDF/WS2 nanocomposite. Further, the inclusion of rGO sheets in the PVDF/WS2 composite allows mobile charge carriers to move freely through the conductive network provided by the rGO basal planes, which improves the internal polarization of the PVDF/WS2/rGO nanocomposites and increases the electrical performance of the piezoelectric nanogenerators (PENGs). The PVDF/WS2/0.3rGO nanocomposite-based PENG exhibits maximum piezoresponses with ~8.1 times enhancements in the output power density than the bare PVDF-based PENG. The mechanism behind the enhanced piezoresponses in the PVDF/WS2/rGO nanocomposites has been discussed. .

Modulation of terpenoid indole alkaloid pathway via elicitation with phytosynthesized silver nanoparticles for the enhancement of ajmalicine, a pharmaceutically important alkaloid.

MAIN CONCLUSION: The use of silver nanoparticles as elicitors in cell cultures of Rauwolfia serpentina resulted in increased levels of ajmalicine, upregulated structural and regulatory genes, elevated MDA content, and reduced activity of antioxidant enzymes. These findings hold potential for developing a cost-effective method for commercial ajmalicine production. Plants possess an intrinsic ability to detect various stress signals, prompting the activation of defense mechanisms through the reprogramming of metabolites to counter adverse conditions. The current study aims to propose an optimized bioprocess for enhancing the content of ajmalicine in Rauwolfia serpentina callus through elicitation with phytosynthesized silver nanoparticles. Initially, callus lines exhibiting elevated ajmalicine content were established. Following this, a protocol for the phytosynthesis of silver nanoparticles using seed extract from Rauwolfia serpentina was successfully standardized. The physicochemical attributes of the silver nanoparticles were identified, including their spherical shape, size ranging from 6.7 to 28.8 nm in diameter, and the presence of reducing-capping groups such as amino, carbonyl, and amide. Further, the findings indicated that the presence of 2.5 mg L-1 phytosynthesized silver nanoparticles in the culture medium increased the ajmalicine content. Concurrently, structural genes (TDC, SLS, STR, SGD, G10H) and regulatory gene (ORCA3) associated with the ajmalicine biosynthetic pathway were observed to be upregulated. A notable increase in MDA content and a decrease in the activities of antioxidant enzymes were observed. A notable increase in MDA content and a decrease in the activities of antioxidant enzymes were also observed. Our results strongly recommend the augmentation of ajmalicine content in the callus culture of R. serpentina through supplementation with silver nanoparticles, a potential avenue for developing a cost-effective process for the commercial production of ajmalicine.

Compliance current controlled volatile and nonvolatile memory in Ag/CoFe2O4/Pt resistive switching device.

We report on the resistive memory effects of a Ag/CoFe2O4/Pt device and a deterministic conversion between volatile and nonvolatile resistive switching (RS) memory through the tuning of current compliance (I CC). For the smaller I CC (10-4 A) the device exhibits volatile RS behavior with an atomically sized conducting filament showing the quantum conductance. For an intermediate I CC (10-2 A) nonvolatile bipolar RS behavior is observed, which could originate from the formation and rupture of filament consisting of Ag ions. The high resistance state (HRS) of the device shows a semiconducting conduction mechanism, whereas the low resistance state (LRS) was found to be Ohmic in nature. The temperature dependent resistance studies and magnetization studies indicated that the electrochemical metallization plays a dominant role in the resistive switching process for volatile and nonvolatile modes through the formation of Ag conducting filaments. For higher I CC (10-1 A) the device permanently switches to LRS. The irreversible RS memory behaviors, observed for higher I CC, could be attributed to the formation of a thick and stable conducting channel formed of oxygen vacancies and Ag ions. The compliance current controlled resistive switching modes with a large memory window make the present device a potential candidate to pave the way for future resistive switching devices.

A ferroelectric nanocomposite-film-based device for harvesting energy from water droplets using both piezoelectric and triboelectric effects.

In this paper, we have demonstrated a novel design of a liquid-solid interface triboelectric nanogenerator based on a ZnO- polyvinylidene fluoride (PVDF) flexible ferroelectric film that employs both piezoelectric and triboelectric properties to produce more electricity from water droplets. The present device gives an output voltage of ∼1.32 V and a short-circuit current of ∼0.32µA from the conventional liquid-solid triboelectric nanogenerator (LSTENG), while an additional open-circuit voltage of ∼2.72 mV and short-circuit current of ∼20 nA is generated from the piezoelectric effect. The mechanism for generating energy in both the piezoelectric and triboelectric components is also discussed. Furthermore, we explored the effect of ions in water on the performance of the LSTENG, and the results were confirmed by Kelvin probe force microscopy measurements. The current work reveals a new LSTENG design and the benefit of employing a ferroelectric polymer as the contacting material rather than other non-piezoelectric materials for the LSTENG.

PANI coupled hierarchical Bi2S3nanoflowers based hybrid nanocomposite for enhanced thermoelectric performance.

Bismuth sulfide (Bi2S3) is a promising material for thermoelectric applications owing to its non-toxicity and high abundance of bismuth (Bi) and sulfur (S) elements on earth. However, its low electrical conductivity drastically reduces the value of the figure of merit (ZT). In this work, we have synthesized three-dimensional (3D) hierarchical Bi2S3nanoflowers (NFs) by the hydrothermal route and further incorporated them with conducting polymer polyaniline (PANI) by simple chemisorption method. We have investigated the thermoelectric properties of the as-prepared Bi2S3NFs and PANI/Bi2S3nanocomposite samples and it is demonstrated that the incorporation of the PANI matrix with the 3D hierarchical Bi2S3NFs provides a conducting substrate for the easy transport of the electrons and reduces the barrier height at the interface, resulting in ∼62% increment in the electrical conductivity as compared to Bi2S3NFs. Moreover, a decrement in the thermal conductivity of the PANI/Bi2S3nanocomposite is observed as compared to pristine Bi2S3NFs due to the increased phonon scattering at the interfaces facilitated by the hierarchical morphology of the NFs. Furthermore, an increment in the electrical conductivity and simultaneous decrement in the thermal conductivity results in an overall ∼20% increment in the figure of merit (ZT) for PANI/Bi2S3nanocomposite as compared to pristine Bi2S3NFs. The work highlights an effective strategy of coupling 3D hierarchical metal chalcogenide with conducting polymer for optimizing their thermoelectric properties.

Hierarchical PANI/ZnO nanocomposite: synthesis and synergistic effect of shape-selective ZnO nanoflowers and polyaniline sensitization for efficient photocatalytic dye degradation and photoelectrochemical water splitting.

Hierarchical nanoflowers (NFs) of zinc oxide (ZnO) have been synthesized in the hexagonal wurtzite structure by a facile hydrothermal method. Polyaniline (PANI) has been prepared by the chemical oxidative polymerization method and incorporated with ZnO NFs by the chemisorption method. The potential of the synthesized nanostructures has been demonstrated for efficient photocatalytic degradation of methylene blue (MB) and photoelectrochemical water splitting. The PANI/ZnO nanocomposite has exhibited the enhanced photocatalytic activity which is ∼9 fold higher in comparison to pristine ZnO NFs and enhanced photocurrent density which is ∼16 fold higher than the ZnO photoanode. Importantly, ∼4 fold increment in the incident photon-to-current conversion efficiency (IPCE) is exhibited by PANI/ZnO, than that of ZnO photoanode. The remarkably enhanced photocatalytic and photoelectrochemical performance of PANI/ZnO nanocomposite is attributed to the availability of more interfacial sites facilitated by the hierarchical ZnO NFs, improved overall photoresponse due to its photosensitization with PANI and the resulting type-II heterojunction between them, which helps in the efficient separation of photogenerated charge carriers at the interface. A plausible reaction mechanism for the substantially improved performance of nanostructured PANI/ZnO towards MB degradation and water splitting has also been elucidated.

Enhanced photoelectrochemical performance of NaNbO3 nanofiber photoanodes coupled with visible light active g-C3N4 nanosheets for water splitting.

Sodium niobate nanofibers (NaNbO3-NF) have been synthesized using a hydrothermal technique and further coupled with visible light responsive graphitic carbon nitride (g-C3N4) nanosheets in different concentration ratios of 2:1 (2-CN), 4:1 (4-CN) and 8:1 (8-CN). A significant improvement in the photoelectrochemical (PEC) performance of the g-C3N4/NaNbO3-NF (4-CN) nanostructured photoanode compared to the bare NaNbO3 photoanode is observed. A current density of 12.55 mA cm-2 at 1 V with respect to the Ag/AgCl reference electrode is achieved for the g-C3N4/NaNbO3-NF (4-CN) photoanode, which is ∼3 times higher than the NaNbO3-NF photoanode. Also, compared to NaNbO3-NF, the g-C3N4/NaNbO3-NF (4-CN) nanocomposite photoanode showed ∼3 times improvement in the incident photon-to-current conversion efficiency. The improvement in the PEC performance of visible light active g-C3N4/NaNbO3-NF (4-CN) nanocomposite is attributed to the improved photoresponse of NaNbO3-NF due to the coupling of g-C3N4 and the formation of a type-II heterojunction between them leading to the enhanced separation of the photogenerated charge carriers. A possible reaction mechanism for the improved PEC water splitting performance has been proposed for the g-C3N4/NaNbO3-NF (4-CN) photoanode.

Effect of graphene nanofillers on the enhanced thermoelectric properties of Bi2Te3 nanosheets: elucidating the role of interface in de-coupling the electrical and thermal characteristics.

In this report, we investigate the effect of graphene nanofillers on the thermoelectric properties of Bi2Te3 nanosheets and demonstrate the role of interface for enhancing the overall figure of merit (ZT) ∼ 53%. The enhancement in the ZT is obtained due to an increase in the electrical conductivity (∼111%) and decrease in the thermal conductivity (∼12%) resulting from increased conducting channels and phonon scattering, respectively at the interfaces between graphene and Bi2Te3 nanosheets. A detailed analysis of the thermal conductivity reveals ∼4 times decrease in the lattice thermal conductivity in contrast to ∼2 times increase in the electronic thermal conductivity after the addition of graphene. Kelvin probe measurements have also been carried which reveals presence of low potential barrier at the interface between graphene and Bi2Te3 nanosheets which assist the flow of charge carriers thereby, increasing the mobility of the carriers. Thus, our results reveals a significant decrease in the lattice thermal conductivity (due to the formation of interfaces) and increase in the electron mobility (due to conducting paths at the interfaces) strongly participate in deciding observed enhancement in the thermoelectric figure of merit.

Very High Surface Area Mesoporous Thin Films of SrTiO3 Grown by Pulsed Laser Deposition and Application to Efficient Photoelectrochemical Water Splitting.

Very high surface area, self-assembled, highly crystalline mesoporous SrTiO3 (STO) thin films were developed for photoelectrochemical water splitting. Much improved performance of these mesoporous films compared to planar STO thin films and any other form of STO such as single crystal samples and nanostructures was demonstrated. The high performance resulted from very large surface area films and optimization of carrier concentration.

A Prospective Study to Evaluate the Clinical and Diffusion Tensor Imaging (DTI) Correlation in Patients with Lumbar Disc Herniation with Radiculopathy.

Introduction: Conventional magnetic resonance imaging findings frequently do not correlate with the symptoms of lumbar disc herniation (LDH). Diffusion-weighted imaging can reveal important details about the microstructure of tissues. This study assessed the role of diffusion-weighted imaging (DTI) in LDH with radiculopathy and explored the relationship between DTI values and clinical scores. Methods: Forty-five patients with LDH with radiculopathy were evaluated via DTI at the intraspinal (IS), intraforaminal (IF), and extraforaminal (EF) levels. A visual analog scale (VAS) was used for low back and leg pain. The Japanese Orthopaedic Association (JOA) scoring system, Oswestry Disability Index (ODI), and Roland-Morris Disability Questionnaire (RMDQ) were used for functional evaluation. Results: There was a statistically significantly (p<0.05) difference between the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values on the affected side compared with those on contralateral normal side. The VAS score had a weak positive correlation with RMDQ score (r=0.279, P=0.050). The JOA score had a moderate negative correlation with RMDQ score (r=-0.428, P=0.002), whereas the ODI score had a moderate positive correlation with RMDQ score (r=0.554, P<0.001). There was a moderate positive correlation between ADC values at the IF level and the RMDQ score on the affected side (r=0.310, P=0.029). There was no correlation between FA values and JOA score. ODI had a significantly positive correlation with the contralateral normal side FA values at the IF (r=0.399, P=0.015), EF (r=0.368, P=0.008) and IS (r=0.343, P=0.015) levels. RMDQ had a weak positive correlation with the contralateral normal side FA values at the IF (r=0.311, P=0.028), IS (r=0.297, P=0.036) and EF (r=0.297, P=0.036) levels. Conclusions: The decrease in FA values and the increase in ADC values are useful markers of compression. ADC correlates well with the patient's neurological symptoms and functional status. Conversely, FA correlates well with the patient's neurological symptoms, but is not correlated well with the functional status.

An overview of the phytosynthesis of various metal nanoparticles.

Nanotechnology is an emerging branch of science wherein various valuable molecules with altered properties can be synthesized and utilized for numerous technological applications. Nowadays, nanotechnology is the preferred tool for the agriculture, food, and medicine industries. However, consistent accumulation of toxic by-products during the synthesis of nanoparticles from the established physical and chemical methods imposes an unprecedented danger to the environment and human well-being. The biological route for the synthesis of nanoparticles offers a potential option over the conventional chemical synthesis process due to the involvement of non-toxic and environmentally friendly materials, such as plants, fungi, bacteria, etc. Phytosynthesis, a type of biological synthesis, utilizes various combinations of secondary metabolites from different plant parts (whole plant, leaves, fruit peel, root, bark, seeds, and stem) for non-toxic and environmentally friendly nanoparticles fabrication. Non-toxic and environmentally friendly secondary metabolites derived from plants are the sources of reducing and capping agents during the biosynthesis of nanoparticles which proceeds in a controlled manner with desired characteristics. Phytosynthesis of nanoparticles is also a simple, economic, durable, and reproducible process. The present article is a comprehensive depiction of the synthesis of different metal nanoparticles from diverse plant species.

Stress dependent band gap shift and valence band studies in ZnO nanorods.

ZnO nanorods are grown on seedless and ZnO seeded glass substrates using chemical solution method and their structural, morphological, optical and valence band studies have been carried out. On seedless substrate horizontal nanorods are observed whereas for the seeded substrates vertically aligned hollow and solid nanorods grows. X-ray diffraction analysis revealed the presence of tensile stress in the vertical nanorods. Blue shift has been observed in the band gap of the vertical nanorods as compared to the horizontal nanorods which is attributed to the presence of tensile stress in the vertically aligned nanorods. Photoluminescence spectra revealed the dominance of Zinc vacancies (V(Zn)) related defects in the nanorods and oxygen defects are found to be higher in the vertically aligned nanorods as compared to the horizontal nanorods. The difference between the Fermi level and valence band maxima for horizontal, hollow vertical and solid vertical nanorods are found to be approximately 0.56 eV, approximately 0.70 eV and approximately 0.92 eV respectively indicating the possibility of p-type of conduction in the nanorods which has been attributed to presence of V(Zn) defects in the ZnO nanorods.

Recent Advances in Semiconductor-Graphene and Semiconductor-Ferroelectric/Ferromagnetic Nanoheterostructures for Efficient Hydrogen Generation and Environmental Remediation.

Semiconductor heterostructures have attracted intensive research attention during the past few years owing to their great potential for energy and environmental remediation related applications. Effective optical absorption and efficient separation of photogenerated charge carriers are among the key factors for achieving high efficiency in a photocatalytic process. This mini-review summarizes state-of-the-art activities in designing nanosemiconductor heterostructures using multifunctional semiconductors for solar-to-hydrogen conversion and degradation of organic pollutants. Various novel design strategies such as semiconductor/graphene heterojunctions including graphene as a semimetal and photosensitizer, semiconductor/ferromagnetic, and semiconductor/ferroelectric nanoheterostructures for enhancing the performance of photocatalytic processes have been discussed. Finally, key challenges and future prospects for designing more efficient photocatalytic materials are briefly outlined.

Growth of Doped SrTiO3 Ferroelectric Nanoporous Thin Films and Tuning of Photoelectrochemical Properties with Switchable Ferroelectric Polarization.

Ferroelectric polarization is an intriguing physical phenomenon for tuning charge-transport properties and finds application in a wide range of optoelectronic devices. So far, ferroelectric materials in a planar geometry or chemically grown nanostructures have been used. However, these structural architectures possess serious disadvantages such as small surface areas and structural defects, respectively, leading to reduced performance. Herein, the growth of room-temperature ferroelectric nanoporous/nanocolumnar structure of Ag,Nb-codoped SrTiO3 (Ag/Nb:STO) using pulsed laser deposition is reported and demonstrated to have enhanced photoelectrochemical (PEC) properties using ferroelectric polarization. By manipulating the external electrical bias, ∼3-fold enhancement in the photocurrent from 40 to 130 µA·cm-2 of film area is obtained. Concurrently, the flat-band potential is decreased from -0.55 to -1.13 V, revealing a giant ferroelectric tuning of the band alignment at the semiconductor surface and enhanced charge transfer. In addition, an electrochemical impedance spectroscopy study confirmed the tuning of the charge transfer with ferroelectric polarization. Our nanoporous ferroelectric-semiconductor approach offers a new platform with great potential for achieving highly efficient PEC devices for renewable energy applications.

Low field magneto-tunable photocurrent in CoFe2O4 nanostructure films for enhanced photoelectrochemical properties.

Efficient solar to hydrogen conversion using photoelectrochemical (PEC) process requires semiconducting photoelectrodes with advanced functionalities, while exhibiting high optical absorption and charge transport properties. Herein, we demonstrate magneto-tunable photocurrent in CoFe2O4 nanostructure film under low applied magnetic fields for efficient PEC properties. Photocurrent is enhanced from ~1.55 mA/cm2 to ~3.47 mA/cm2 upon the application of external magnetic field of 600 Oe leading to ~123% enhancement. This enhancement in the photocurrent is attributed to the reduction of optical bandgap and increase in the depletion width at CoFe2O4/electrolyte interface resulting in an enhanced generation and separation of the photoexcited charge carriers. The reduction of optical bandgap in the presence of magnetic field is correlated to the shifting of Co2+ ions from octahedral to tetrahedral sites which is supported by the Raman spectroscopy results. Electrochemical impedance spectroscopy results confirm a decrease in the charge transfer resistance at the CoFe2O4/electrolyte interface in the presence of magnetic field. This work evidences a coupling of photoexcitation properties with magnetic properties of a ferromagnetic-semiconductor and the effect can be termed as magnetophototronic effect.

Synthesis and Phase Transformation Studies of Dysprosium-Doped Bi4V2O11 Nanoparticles and Their Application in Visible Light Photocatalytic Degradation of Tetracycline Drug.

Recently, Bi4V2O11 as an electrolyte material has pulled in considerable consideration because of its remarkable novel applications. In this article, novel, dysprosium-doped (x = 0.2, 0.3, 0.4, and 0.5) Bi4V2O11 (Dy/BVO) nanoparticles have been synthesized by sol-gel strategy. The photocatalyst Dy/BVO nanoparticles exhibit higher photocatalytic efficiency than BVO nanoparticles assessed by debasement of tetracycline drug under visible light illumination. Our work focuses on the phase transformation, conducting properties, and mechanisms of the Dy/BVO nanoparticles in relation to execute some methods of processing and manufacturing product in commercial applications. The characterization of Dy/BVO was performed by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and UV-vis analysis. ac impedance spectroscopy was used to analyze the conducting behavior of synthesized nanoparticles in the temperature range 100-600 °C. The photocatalytic activity revealed that Dy/BVO remarkably enhanced the photocatalytic activity. This is the first report that Dy/BVO can destroy the drug effluent which is coming from the drug industry and also worried about the human health hazards.

Valence Change Bipolar Resistive Switching Accompanied With Magnetization Switching in CoFe2O4 Thin Film.

Resistive Switching in oxides has offered new opportunities for developing resistive random access memory (ReRAM) devices. Here we demonstrated bipolar Resistive Switching along with magnetization switching of cobalt ferrite (CFO) thin film using Al/CFO/FTO sandwich structure, which makes it a potential candidate for developing future multifunctional memory devices. The device shows good retention characteristic time (>104 seconds) and endurance performance, a good resistance ratio of high resistance state (HRS) and low resistance state (LRS) ~103. Nearly constant resistance values in LRS and HRS confirm the stability and non-volatile nature of the device. The device shows different conduction mechanisms in the HRS and LRS i.e. Schottky, Poole Frenkel and Ohmic. Magnetization of the device is also modulated by applied electric field which has been attributed to the oxygen vacancies formed/annihilated during the voltage sweep and indicates the presence of valence change mechanism (VCM) in our device. It is suggested that push/pull of oxygen ions from oxygen diffusion layer during voltage sweep is responsible for forming/rupture of oxygen vacancies conducting channels, leading to switching between LRS and HRS and for switching in magnetization in CFO thin film. Presence of VCM in our device was confirmed by X-ray Photoelectron Spectroscopy at Al/CFO interface.

Extended nasolabial flap compared with the platysma myocutaneous muscle flap for reconstruction of intraoral defects after release of oral submucous fibrosis: a comparative study.

We compared extended nasolabial flaps and coronoidectomy with platysma myocutaneous muscle flaps in the management of 20 randomly selected patients with histologically confirmed oral submucous fibrosis. Ten patients were treated by release of fibrous bands, bilateral coronoidectomy, and reconstruction with an extended nasolabial flap (nasolabial group), and the other 10 by bilateral release of fibrous bands, coronoidectomy, and reconstruction with a platysma myocutaneous muscle flap (platysma group). In the nasolabial group the mean preoperative interincisal mouth opening was 12(range 3-14)mm, and in the platysma group it was 11 (3-13). All 20 patients were given vigorous postoperative physiotherapy, and were followed up for 3 years. The interincisal mouth opening improved to 47(35-45)mm in the nasolabial group and 48(41-52)mm in the platysma group. The procedures were equally effective in the management of the oral submucous fibrosis, except that the extraoral scar was not aesthetically acceptable in the nasolabial group.