23 research outputs found
Facile and time-resolved chemical growth of nanoporous CaxCoO2 thin films for flexible and thermoelectric applications
CaxCoO2 thin films can be promising for widespread flexible thermoelectric
applications in a wide temperature range from room-temperature self-powered
wearable applications (by harvesting power from body heat) to energy harvesting
from hot surfaces (e.g., hot pipes) if a cost-effective and facile growth
technique is developed. Here, we demonstrate a time resolved, facile and
ligand-free soft chemical method for the growth of nanoporous Ca0.35CoO2 thin
films on sapphire and mica substrates from a water-based precursor ink,
composed of in-situ prepared Ca2+-DMF and Co2+-DMF complexes. Mica serves as
flexible substrate as well as sacrificial layer for film transfer. The grown
films are oriented and can sustain bending stress until a bending radius of 15
mm. Despite the presence of nanopores, the power factor of Ca0.35CoO2 film is
found to be as high as 0.50 x 10-4 Wm-1K-2 near room temperature. The present
technique, being simple and fast to be potentially suitable for cost-effective
industrial upscaling.Comment: 16 pages, 5 figure
Design of In Situ Poled Ce<sup>3+</sup>-Doped Electrospun PVDF/Graphene Composite Nanofibers for Fabrication of Nanopressure Sensor and Ultrasensitive Acoustic Nanogenerator
We
report an efficient, low-cost in situ poled fabrication strategy to
construct a large area, highly sensitive, flexible pressure sensor
by electrospun Ce<sup>3+</sup> doped PVDF/graphene composite nanofibers.
The entire device fabrication process is scalable and enabling to
large-area integration. It can able to detect imparting pressure as
low as 2 Pa with high level of sensitivity. Furthermore, Ce<sup>3+</sup>-doped PVDF/graphene nanofiber based ultrasensitive pressure sensors
can also be used as an effective nanogenerator as it generating an
output voltage of 11 V with a current density ∼6 nA/cm<sup>2</sup> upon repetitive application of mechanical stress that could
lit up 10 blue light emitting diodes (LEDs) instantaneously. Furthermore,
to use it in environmental random vibrations (such as wind flow, water
fall, transportation of vehicles, etc.), nanogenerator is integrated
with musical vibration that exhibits to power up three blue LEDs instantly
that promises as an ultrasensitive acoustic nanogenerator (ANG). The
superior sensing properties in conjunction with mechanical flexibility,
integrability, and robustness of nanofibers enabled real-time monitoring
of sound waves as well as detection of different type of musical vibrations.
Thus, ANG promises to use as an ultrasensitive pressure sensor, mechanical
energy harvester, and effective power source for portable electronic
and wearable devices
An Effective Electrical Throughput from PANI Supplement ZnS Nanorods and PDMS-Based Flexible Piezoelectric Nanogenerator for Power up Portable Electronic Devices: An Alternative of MWCNT Filler
An Effective Electrical Throughput from PANI Supplement ZnS Nanorods and PDMS-Based Flexible Piezoelectric Nanogenerator for Power up Portable Electronic Devices: An Alternative of MWCNT Filler
We demonstrate the requirement of
electrical poling can be avoided in flexible piezoelectric nanogenerators
(FPNGs) made of low-temperature hydrothermally grown wurtzite zinc
sulfide nanorods (ZnS-NRs) blended with polydimethylsiloxane (PDMS).
It has been found that conductive fillers, such as polyaniline (PANI)
and multiwall carbon nanotubes (MWCNTs), can subsequently improve
the overall performance of FPNG. A large electrical throughput (open
circuit voltage ∼35 V with power density ∼2.43 μW/cm<sup>3</sup>) from PANI supplement added nanogenerator (PZP-FPNG) indicates
that it is an effective means to replace the MWCNTs filler. The time
constant (Ï„) estimated from the transient response of the capacitor
charging curves signifying that the FPNGs are very much capable to
charge the capacitors in very short time span (e.g., 3 V is accomplished
in 50 s) and thus expected to be perfectly suitable in portable, wearable
and flexible electronics devices. We demonstrate that FPNG can instantly
lit up several commercial Light Emitting Diodes (LEDs) (15 red, 25
green, and 55 blue, individually) and power up several portable electronic
gadgets, for example, wrist watch, calculator, and LCD screen. Thus,
a realization of potential use of PANI in low-temperature-synthesized
ZnS-NRs comprising piezoelectric based nanogenerator fabrication is
experimentally verified so as to acquire a potential impact in sustainable
energy applications. Beside this, wireless piezoelectric signal detection
possibility is also worked out where a concept of self-powered smart
sensor is introduced
Self-Poled Transparent and Flexible UV Light-Emitting Cerium Complex–PVDF Composite: A High-Performance Nanogenerator
CeriumÂ(III)-<i>N</i>,<i>N</i>-dimethylformamide-bisulfate
[CeÂ(DMF)Â(HSO<sub>4</sub>)<sub>3</sub>] complex is doped into polyÂ(vinylidene
fluoride) (PVDF) to induce a higher yield (99%) of the electroactive
phases (β- and γ-phases) of PVDF. A remarkable enhancement
of the output voltage (∼32 V) of a nanogenerator (NG) based
on a nonelectrically poled ceriumÂ(III) complex containing PVDF composite
film is achieved by simple repeated human finger imparting, whereas
neat PVDF does not show this kind of behavior. This high electrical
output resembles the generation of self-poled electroactive β-phase
in PVDF due to the electrostatic interactions between the fluoride
of PVDF and the surface-active positive charge cloud of the cerium
complex via H-bonding and/or bipolar interaction among the opposite
poles of cerium complex and PVDF, respectively. The capacitor charging
capability of the flexible NG promises its applicability as piezoelectric-based
energy harvester. The ceriumÂ(III) complex doped PVDF composite film
exhibit an intense photoluminescence in the UV region, which might
be due to a participation of electron cloud from negative pole of
bipolarized PVDF. This fact may open a new area for prospective development
of high-performance energy-saving flexible solid-state UV light emitters
Bacterial Fucose-Rich Polysaccharide Stabilizes MAPK-Mediated Nrf2/Keap1 Signaling by Directly Scavenging Reactive Oxygen Species during Hydrogen Peroxide-Induced Apoptosis of Human Lung Fibroblast Cells
<div><p>Continuous free radical assault upsets cellular homeostasis and dysregulates associated signaling pathways to promote stress-induced cell death. In spite of the continuous development and implementation of effective therapeutic strategies, limitations in treatments for stress-induced toxicities remain. The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms. In two different fermentation processes, <i>Bacillus megaterium</i> RB-05 biosynthesized two non-identical fucose polysaccharides; of these, the polysaccharide having a high-fucose content (∼42%) conferred the maximum free radical scavenging efficiency <i>in vitro</i>. Structural characterizations of the purified polysaccharides were performed using HPLC, GC-MS, and <sup>1</sup>H/<sup>13</sup>C/2D-COSY NMR. H<sub>2</sub>O<sub>2</sub> (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis. The polysaccharide (250 µg/mL) attenuated the cell death process by directly scavenging intracellular ROS rather than activating endogenous antioxidant enzymes. This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases). Furthermore, cellular homeostasis was re-established via stabilization of MAPK-mediated Nrf2/Keap1 signaling and transcription of downstream cytoprotective genes. This molecular study uniquely introduces a fucose-rich bacterial polysaccharide as a potential inhibitor of H<sub>2</sub>O<sub>2</sub>-induced stress and toxicities.</p></div
The effect of HFC polysaccharide on H<sub>2</sub>O<sub>2</sub>-induced morphological changes in WI38 cells.
<p>The cells were incubated in presence (100, 200 and 250 µg/mL) or in absence of HFC polysaccharide for 1 h followed by the treatment with 300 µM H<sub>2</sub>O<sub>2</sub> in both the cases for varying periods of time (0–24 h). Cell morphology was observed under microscope in phase contrast mode. Results are representative of three independent experiments performed in triplicate. Indicated <i>scale bars</i> signify 50 µm distance and photographs were taken at 10× zoom.</p
The effects of HFC polysaccharide treatment on H<sub>2</sub>O<sub>2</sub>-induced regulation of mitochondrial functions.
<p>The polysaccharide prevented H<sub>2</sub>O<sub>2</sub>-induced changes in the expression of Bcl2 family at both mRNA and protein level. WI38 cells were incubated in presence (200 and 250 µg/mL) or in absence of HFC polysaccharide for 1 h followed by the treatment with 300 µM H<sub>2</sub>O<sub>2</sub> in both the cases for varying periods of time (0–24 h). <b>A)</b> Mitochondrial membrane potential (MMP) was monitored by DiOC6 staining with flow cytometry. The mean fluorescence indices (MFI) are shown as bar graphs. <b>B)</b> Protein level expression of Bcl2, Bcl-xl, and Bad was evaluated by immunoblotting. β-actin was used as loading control. Fold changes are represented as relative values of band densitometries normalized to control and are shown as numbers below the immunoblots. Results are representative of three independent experiments performed in triplicate and are represented as mean value. <b>C)</b> The ratio between Bax and Bcl2 were calculated from band densitometries of corresponding protein level expressions and are shown as bar graphs. <b>D)</b> Fold changes of Bcl2, Bcl-xl, Bad, Bax, and cytochrome c at mRNA level were calculated using real-time RT-PCR (SYBR green method). Fold changes are represented as relative values normalized to control and quantified in the terms of 2<sup>−ΔΔCt</sup>. GAPDH was used as internal control. Results are representative of three independent experiments performed in triplicate and are represented as mean ± SD. A one-way analysis of variance (ANOVA, Bonferroni corrections for multiple comparisons) was performed, where significant level stands for * p<0.05, ** p<0.001, *** p<0.0001.</p
Translocation of Bax and cytochrome c induced by H<sub>2</sub>O<sub>2</sub> and HFC polysaccharide during the stress and polysaccharide treatment period, respectively.
<p>WI38 cells were incubated in presence (250 µg/mL) or in absence of HFC polysaccharide for 1 h followed by the treatment with 300 µM H<sub>2</sub>O<sub>2</sub> in both the cases for varying periods of time (0–24 h). <b>A)</b> Protein level expression of Bax and cytochrome c in both cytosolic and mitochondrial fractions was observed by immunoblotting. β-actin and COX4 were used as loading control. Fold changes are represented as relative values of band densitometries normalized to control and are shown as numbers below the immunoblots. Results are representative of three independent experiments performed in triplicate and are represented as mean value. A one-way analysis of variance (ANOVA, Bonferroni corrections for multiple comparisons) was performed, where significant level stands for * p<0.05, ** p<0.001. <b>B)</b> H<sub>2</sub>O<sub>2</sub>-induced release of cytochrome c from mitochondria to cytosol and re-localization into mitochondria again during the polysaccharide treatment were monitored under fluorescence microscope using fluorescence-tagged (green florescence) specific antibodies. Similarly, mitochondrial translocation of Bax and their cytosolic re-localization was also tracked following the same procedure. The cells were treated with 100 nM MitoTracker Red (red florescence) for 30 min before cell-fixation for mitochondrial staining. Each image shown is representative of 20 random fields observed. Indicated <i>scale bars</i> signify 10 µm distance and photographs were taken at 100× zoom.</p
Plausible signaling cross-talk involved in the HFC polysaccharide treatment against H<sub>2</sub>O<sub>2</sub>-induced apoptosis of WI38 cells.
<p>Plausible signaling cross-talk involved in the HFC polysaccharide treatment against H<sub>2</sub>O<sub>2</sub>-induced apoptosis of WI38 cells.</p