229 research outputs found
Evaluation of the hydrogen solubility and diffusivity in proton-conducting oxides by converting the PSL values of a tritium imaging plate
Proton-conducting oxides have potential applications in hydrogen sensors,
hydrogen pumps, and other electrochemical devices including the tritium
purification and recovery systems of nuclear fusion reactors. Although the
distribution of hydrogen (H) in such oxide materials is an important aspect,
its precise measurement is difficult. In the present study, the hydrogen
solubility and diffusivity behavior of BaZr0.9Y0.1O2.95 (BZY),
BaZr0.955Y0.03Co0.015O2.97 (BZYC), and CaZr0.9In0.1O2.95 (CZI) were studied
using tritiated heavy water vapor i.e., DTO (~2 kPa, tritium (T) = 0.1%) by
converting the photostimulated luminescence (PSL) values of the imaging plate
(IP). The samples were exposed to DTO vapor at 673 K for 2 h or at 873 K for 1
h. The disc-shaped oxide specimens (diameter ~7.5 mm; thickness ~2.3 mm;
theoretical density (TD) > 98 %) were prepared by conventional powder
metallurgy. The IP images of the specimen surfaces of all the three materials
T-exposed revealed that BZY showed the most uniform T distribution with the
highest tritium activity. The cross-sectional T concentration profiles of the
cut specimens showed that T diffused deeper into BZY and BZYC than into CZI.
The hydrogen solubility and diffusivity in the CZI specimen were lower than
that in the BZY and BZYC specimens. This suggested that barium zirconates were
more favorable proton conductors than calcium zirconates.Comment: 19 pages, 12 figure
Recent progress of fabrication, characterization, and applications of anodic aluminum oxide (AAO) membrane: A review
The progress of membrane technology with the development of membranes with
controlled parameters led to porous membranes. These membranes can be formed
using different methods and have numerous applications in science and
technology. Anodization of aluminum in this aspect is an electro-synthetic
process that changes the surface of the metal through oxidation to deliver an
anodic oxide layer. This process results in a self-coordinated, exceptional
cluster of round and hollow formed pores with controllable pore widths,
periodicity, and thickness. After the initial introduction, the paper proceeds
with a brief overview of anodizing process. That engages anodic aluminum oxide
(AAO) layers to be used as formats in various nanotechnology applications
without the necessity for expensive lithographical systems. This review article
surveys the current status of the investigation on AAO membranes. A
comprehensive analysis is performed on AAO membranes in applications;
filtration, sensors, drug delivery, template-assisted growth of various
nanostructures. Their multiple usages in nanotechnology have also been
discussed to gather nanomaterials and devices or unite them into specific
applications, such as nano-electronic gadgets, channel layers, and clinical
platforms tissue designing. From this review, the fact that the specified
enhancement of properties of AAO can be done by varying geometric parameters of
AAO has been highlighted. No review paper focused on a detailed discussion of
applications of AAO with prospects and challenges. This review paper represents
the formation, properties, applications with objective consideration of the
prospects and challenges of AAO applications. The prospects may appeal to
researchers to promote the development of unique membranes with
functionalization and controlled geometric parameters and check the feasibility
of the AAO membranes in nano-devices.Comment: 36 pages, 19 figures, 8 table
A Review of Applications, Prospects, and Challenges of Proton-Conducting Zirconates in Electrochemical Hydrogen Devices
In the future, when fossil fuels are exhausted, alternative energy sources
will be essential for everyday needs. Hydrogen-based energy can play a vital
role in this aspect. This energy is green, clean, and renewable.
Elec-trochemical hydrogen devices have been used extensively in nuclear power
plants to manage hydrogen-based renewable fuel. Doped zirconate materials are
commonly used as an electrolyte in these electrochemical devices. These
materials have excellent physical stability and high proton transport numbers,
which make them suitable for multiple applications. Doping enhances the
physical and electronic properties of zirconate materials and makes them ideal
for practical applications. This review highlights the applications of
zirconate-based pro-ton-conducting materials in electrochemical cells,
particularly in tritium monitors, tritium recovery, hydrogen sensors, and
hydrogen pump systems. The central section of this review summarizes recent
investigations and provides a comprehensive insight into the various doping
schemes, experimental setup, instrumentation, op-timum operating conditions,
morphology, composition, and performance of zirconate electrolyte materials. In
addition, different challenges that are hindering zirconate materials from
achieving their full potential in elec-trochemical hydrogen devices are
discussed. Finally, this paper lays out a few pathways for aspirants who wish
to undertake research in this field.Comment: 31 pages, 13 figure
A comprehensive first principles calculations on (Ba0.82K0.18)(Bi0.53Pb0.47)O3 single-cubic-perovskite superconductor
In this present study, the pseudopotential plane-wave (PP-PW) pathway in the
scheme of density functional theory (DFT) is utilized to investigate the
various physical properties on (Ba0.82K0.18)(Bi0.53Pb0.47)O3 (BKBPO) single
perovskite superconductor. We have analyzed elastic constants and moduli at
zero and elevated pressures (up to 25 GPa) as well. We also have investigated
the anisotropic nature incorporating both the theoretical indices and graphical
representations in 2D and 3D dimensions, which reveals a high level of
anisotropy. The flatness of the energy bands near EF is a sign of Van-Hf
singularity that might increase the electron pairing and origination of high-TC
superconductivity. The computed band structure exhibits its metallic
characteristics is confirmed by band overlapping. A band of DOS is formed for
the strong hybridization of the constituent elements. The orbital electrons of
O-2p contribute most dominantly at EF in contrast to all orbital electrons. The
orbital electrons at the EF are higher from both the partial density of states
and charge density mapping investigation. The coexistence of the electron and
hole-like Fermi sheets exhibits the multi-band nature of BKBPO. On the other
hand, Fermi surfaces with flat faces promote transport features and Fermi
surface nesting as well. The calculated value of the electron-phonon coupling
constant ({\lambda} = 1.46) is slightly lower than the isostructural
superconductor, which indicates that the studied BKBPO can be treated as a
strongly coupled superconductor similar to the reported isostructural
perovskite superconductors. Furthermore, the thermodynamic properties have been
evaluated and analyzed at elevated temperature and pressure by using harmonic
Debye approximation (QHDA).Comment: 20 pages, 7 figures, 6 table
Combined DFT, SCAPS-1D, and wxAMPS frameworks for design optimization of efficient Cs2BiAgI6-based perovskite solar cells with different charge transport layers
In this study, combined DFT, SCAPS-1D, and wxAMPS frameworks are used to
investigate the optimized designs of Cs2BiAgI6 double perovskite-based solar
cells. The first-principle calculation is employed to investigate the
structural stability, optical responses, and electronic contribution of the
constituent elements in Cs2BiAgI6 absorber material, where SCAPS-1D and wxAMPS
simulators are used to scrutinize different configurations of Cs2BiAgI6 solar
cells. Here, PCBM, ZnO, TiO2, C60, IGZO, SnO2, WS2, and CeO2 are used as ETL,
and Cu2O, CuSCN, CuSbS2, NiO, P3HT, PEDOT: PSS, Spiro-MeOTAD, CuI, CuO, V2O5,
CBTS, CFTS are used as HTL, and Au is used as a back contact. About ninety-six
combinations of Cs2BiAgI6-based solar cell structures are investigated, in
which eight sets of solar cell structures are identified as the most efficient
structures. Besides, holistic investigation on the effect of different factors
such as the thickness of different layers, series and shunt resistances,
temperature, capacitance, Mott-Schottky and generation-recombination rates, and
J-V (current-voltage density) and QE (quantum efficiency) characteristics is
performed. The results show CBTS as the best HTL for Cs2BiAgI6 with all eight
ETLs used in this work, resulting in a power conversion efficiency (PCE) of
19.99%, 21.55%, 21.59%, 17.47%, 20.42%, 21.52%, 14.44%, 21.43% with PCBM, TiO2,
ZnO, C60, IGZO, SnO2, CeO2, WS2, respectively. The proposed strategy may pave
the way for further design optimization of lead-free double perovskite solar
cells.Comment: 36 pages, 14 figures, 6 table
Effect of various electron and hole transport layers on the performance of CsPbI3-based perovskite solar cells: A numerical investigation in DFT, SCAPS-1D, and wxAMPS frameworks
CsPbI3 has recently received tremendous attention as a possible absorber of
perovskite solar cells (PSCs). However, CsPbI3-based PSCs have yet to achieve
the high performance of the hybrid PSCs. In this work, we performed a density
functional theory (DFT) study using the Cambridge Serial Total Energy Package
(CASTEP) code for the cubic CsPbI3 absorber to compare and evaluate its
structural, electronic, and optical properties. The calculated electronic band
gap (Eg) using the GGA-PBE approach of CASTEP was 1.483 eV for this CsPbI3
absorber. Moreover, the computed density of states (DOS) exhibited the dominant
contribution from the Pb-5d orbital, and most charge also accumulated for the
Pb atom as seen from the electronic charge density map. Fermi surface
calculation showed multiband character, and optical properties were computed to
investigate the optical response of CsPbI3. Furthermore, we used IGZO, SnO2,
WS2, CeO2, PCBM, TiO2, ZnO, and C60 as the electron transport layers (ETLs),
and Cu2O, CuSCN, CuSbS2, Spiro-MeOTAD, V2O5, CBTS, CFTS, P3HT, PEDOT: PSS, NiO,
CuO, and CuI as the hole transport layers (HTLs) to identify the best
HTL/CsPbI3/ETL combinations using the SCAPS-1D solar cell simulation software.
Among 96 device structures, the best-optimized device structure,
ITO/TiO2/CsPbI3/CBTS/Au was identified, which exhibited an efficiency of 17.9%.
The effect of absorber and ETL thickness, series resistance, shunt resistance,
and operating temperature was also evaluated for the six best devices along
with their corresponding generation rate, recombination rate,
capacitance-voltage, current density-voltage, and quantum efficiency
characteristics. The obtained results from SCAPS-1D were also compared with
wxAMPS simulation software.Comment: 34 pages, 12 figures, Supporting Information (3 figures
Design and numerical investigation of cadmium telluride (CdTe) and iron silicide (FeSi2) based double absorber solar cells to enhance power conversion efficiency
Inorganic CdTe and FeSi2-based solar cells have recently drawn a lot of
attention because they offer superior thermal stability and good optoelectronic
properties compared to conventional solar cells. In this work, a unique
alternative technique is presented by using FeSi2 as a secondary absorber layer
and In2S3 as the window layer for improving photovoltaic (PV) performance
parameters. Simulating on SCAPS-1D, the proposed double-absorber
(Cu/FTO/In2S3/CdTe/FeSi2/Ni) structure is thoroughly examined and analyzed. The
window layer thickness, absorber layer thickness, acceptor density (NA), donor
density (ND), defect density (Nt), series resistance (RS), and shunt resistance
(Rsh) were simulated in detail for optimization of the above configuration to
improve PV performance. According to this study, 0.5 um is the optimized
thickness for both the CdTe and FeSi2 absorber layers in order to maximize
efficiency. Here, the value of the optimum window layer thickness is 50 nm. For
using CdTe as a single absorber, the efficiency is achieved by 13.26%. But for
using CdTe and FeSi2 as a dual absorber, the efficiency is enhanced and the
obtaining value is 27.35%. The other parameters are also improved and the
obtaining values for fill factor (FF) are 83.68%, open-circuit voltage (Voc) is
0.6566V, and short circuit current density (JSc) is 49.78 mA/cm2. Furthermore,
the proposed model performs good at 300 K operating temperature. The addition
of the FeSi2 layer to the cell structure has resulted in a significant quantum
efficiency (QE) enhancement because of the rise in solar spectrum absorption at
longer wavelengths. The findings of this work offer a promising approach for
producing high-performance and reasonably priced CdTe-based solar cells.Comment: 17 pages, 10 figure
Evaluation of compliance and outcomes of a management protocol for massive postpartum hemorrhage at a tertiary care hospital in Pakistan
<p>Abstract</p> <p>Background</p> <p>Massive postpartum hemorrhage is a life threatening obstetric emergency. In order to prevent the complications associated with this condition, an organized and step-wise management protocol should be immediately initiated.</p> <p>Methods</p> <p>An evidence based management protocol for massive postpartum hemorrhage was implemented at Aga Khan University Hospital, Karachi, Pakistan after an audit in 2005. We sought to evaluate the compliance and outcomes associated with this management protocol 3 years after its implementation. A review of all deliveries with massive primary postpartum hemorrhage (blood loss ≥ 1500 ml) between January, 2008 to December, 2008 was carried out. Information regarding mortality, mode of delivery, possible cause of postpartum hemorrhage and medical or surgical intervention was collected. The estimation of blood loss was made via subjective and objective assessment.</p> <p>Results</p> <p>During 2008, massive postpartum hemorrhage occurred in 0.64% cases (26/4,052). No deaths were reported. The mean blood loss was 2431 ± 1817 ml (range: 1500 - 9000 ml). Emergency cesarean section was the most common mode of delivery (13/26; 50%) while uterine atony was the most common cause of massive postpartum hemorrhage (14/26; 54%). B-lynch suture (24%) and balloon tamponade (60%) were used more commonly as compared to our previously reported experience. Cesarean hysterectomy was performed in 3 cases (12%) for control of massive postpartum hemorrhage. More than 80% compliance was observed in 8 out of 10 steps of the management protocol. Initiation of blood transfusion at 1500 ml blood loss (89%) and overall documentation of management (92%) were favorably observed in most cases.</p> <p>Conclusion</p> <p>This report details our experience with the practical implementation of a management protocol for massive postpartum hemorrhage at a tertiary care hospital in a developing country. With the exception of arterial embolization, relatively newer, simpler and potentially safer techniques are now being employed for the management of massive postpartum hemorrhage at our institution. Particular attention should be paid to the documentation of the management steps while ensuring a stricter adherence to the formulated protocols and guidelines in order to further ameliorate patient outcomes in emergency obstetrical practice. More audits like the one we performed are important to recognize and rectify any deficiencies in obstetrical practice in developing countries. Dissemination of the same is pivotal to enable an open discourse on the improvement of existing obstetrical strategies.</p
Conductive textiles for signal sensing and technical applications
Conductive textiles have found notable applications as electrodes and sensors capable of detecting biosignals like the electrocardiogram (ECG), electrogastrogram (EGG), electroencephalogram (EEG), and electromyogram (EMG), etc; other applications include electromagnetic shielding, supercapacitors, and soft robotics. There are several classes of materials that impart conductivity, including polymers, metals, and non-metals. The most significant materials are Polypyrrole (PPy), Polyaniline (PANI), Poly(3,4-ethylenedioxythiophene) (PEDOT), carbon, and metallic nanoparticles. The processes of making conductive textiles include various deposition methods, polymerization, coating, and printing. The parameters, such as conductivity and electromagnetic shielding, are prerequisites that set the benchmark for the performance of conductive textile materials. This review paper focuses on the raw materials that are used for conductive textiles, various approaches that impart conductivity, the fabrication of conductive materials, testing methods of electrical parameters, and key technical applications, challenges, and future potential
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