Enhancement of solubility and release profile of simvastatin by co-crystallization with citric acid

Purpose: To enhance the solubility and dissolution profile of simvastatin (SIM) via co-crystallization with varying levels of citric acid using various techniques. Method: Simvastatin-citric acid (SIM-CA) co-crystals were prepared using dry grinding, slurry, liquidassisted grinding, and solvent evaporation techniques, and their various properties were compared. A total of twelve formulations (CC01 to CC12) were prepared. Optimized formulations were selected on the basis of dissolution profiles. Flow properties were evaluated using micromeritic analysis, yielding angle of repose, Carr’s index and Hausner’s ratio. Zeta sizer was employed to evaluate particle size distribution, while surface morphology was determined using scanning electron microscopy (SEM). Melting temperature, stability and physical interaction of simvastatin-citric acid co-crystals were determined by thermal analysis and FTIR. The crystalline nature of the co-crystals was evaluated by powder x-ray diffraction analysis, while solubility and dissolution studies were performed to determine in vitro drug release behavior. Results: Micromeritic analysis revealed good flow properties of SIM-CA co-crystals. Results of Zeta sizer analysis showed that the particle sizes of the co-crystals were in the nanometer range, while SEM revealed that the co-crystals had regular cubical shape. Thermal stability studies with TGA and DSC showed that the co-crystals were stable at temperatures exceeding 400 oC. FTIR results revealed minor shifts in 2956 and 1706 cm-1 peaks. Co-crystal formation was confirmed by PXRD data. The drug release profiles of the optimized formulations (CC02, CC07 and CC11) were 11.36 - 94.46, 12.36 - 95.46 and 13.36 - 96.46 %, respectively. There was significant improvement in solubilities of the optimum formulations, with values of 310.18, 427.21 and 522.02 % for CC02, CC07 and CC11, respectively. Conclusion: Citric acid improves the solubility and dissolution profile of the poorly water-soluble drug, simvastatin, which suggests that co-crystallization can potentially enhance the bioavailability of the drug

Metal halide-based photodetector using one-dimensional MAPbI3 micro rods

In the present work, we report the fabrication of a photodetector using methylammonium lead iodide perovskite (MAPbI3) micro rod. Photosensitivity of the Ag/MAPbI3/Ag photodetector has been studied under various light intensities ranging from 10 to 100 mW/cm2. The MAPbI3 perovskite micro rod-based photodetector shows a high on/off ratio (4.47 × 105), and fast response & recovery times (2.7 ms, each), as compared to the photodetectors using perovskite films. This work could initiate new perspectives for perovskite micro rods to be employed in high-performance optoelectronic devices.Open Access funding provided by the Qatar National Library. The authors are highly thankful to the Center of Advanced Materials (CAM), Qatar University, for providing the lab facilities to perform this work

Design and optimization of four-terminal mechanically stacked and optically coupled silicon/perovskite tandem solar cells with over 28% efficiency

Silicon/perovskite tandem devices are believed to be a favorite contender for improving cell performance over the theoretical maximum value of single-junction photovoltaic (PV) cells. The present study evaluates the design and optimization of four-terminal (4-T) mechanically stacked and optically coupled configurations using SCAPS (solar cell capacitance simulator). Low-cost, stable, and easily processed semitransparent carbon electrode-based perovskite solar cells (c-PSCs) without hole transport material (HTM) and highly efficient crystalline silicon (c-Si) PV cells were utilized as top and bottom cells, respectively. The wide bandgap multi-cation perovskite Csx(FA0.4MA0.6)1−xPbI2.8Br0.2 and a low bandgap c-Si were employed as light-harvesting layers in the top and bottom cells, respectively. The impact of perovskite thickness and doping concentrations were examined and optimized for both tandem configurations. Under optimized conditions, thicknesses of 1000 nm and 1100 nm are the best values of the perovskite absorber layer for 4-T mechanically stacked and optically coupled arrangements, respectively. Likewise, 1 × 1017 cm−3 doping concentration of top cells revealed the highest performance in both structures. With these optimized parameters under tandem configurations, efficiency values of 28.38% and 29.34% were obtained in 4-T mechanically and optically coupled tandems, respectively. Results suggest that by optimizing perovskite thickness and doping concentration, the proposed designs using HTM-free c-PSCs could enhance device performance.The article processing charges (APCs) are funded by the Qatar National Library, Qatar

Enhancement of electronic and charge transport properties of NiPc by potassium-tetrasulpho group

a b s t r a c t We report significant enhancement in the electronic properties of nickel phthalocyanine (NiPc) by attaching a potassium-tetrasulpho functional group to synthesize its water soluble derivative nickel (II)4,4 0 ,4 00 ,4' 00 potassium-tetrasulphophthalocyanine (K 4 NiTSPc). To study the potential of this organic compound for electronics applications, Au/K4NiTSPc/Ag diodes have been fabricated and their electronic parameters have been calculated. The mobility and conductivity of the device have been found to be 1.5 Â 10 À 4 cm 2 V À 2 S À 1 and 2.5 Â 10 NiTSPc has shown much better electronic properties as compared to NiPc reported in the literature, which makes it a promising candidate for its potential use in electronics applications

Conceptual Model of Design Creativity: Fostering Creative Cognition in Architecture and Design Pedagogy

Creativity in architecture and design disciplines is highly commended, considered essential in design processes, and regarded as invaluable to the prosperity and survival of design organizations. Creativity is also considered a vital learning outcome in architecture and design pedagogy. Many teachers strive to cultivate creativity in their students and consider it as essential for shaping successful architects and designers. This research proposes a Conceptual Model of Design Creativity based on a synthesis of knowledge from architecture and design pedagogy and creative practice, and understandings of creativity from cognitive psychology and neurocognitive science. The purpose of the proposed model is to articulate the constituents necessary for conceptualizing design creativity and creative design processes. The model also provides the means for understanding how creativity emerges and what is involved in fostering creative cognition in the context of design pedagogy for architecture and other design disciplines. The research also proposes a Design Creativity Cards tool. The purpose of the tool is to help design students stimulate cognitive mechanisms and styles commonly associated with the production of creative results. This research adopts a mixed-methods qualitative research approach for a crossdisciplinary synthesis of creativity research between the literature on creativity from cognitive psychology and neurocognitive science and the literature on architecture and design pedagogy and practice. The development of the Conceptual Model of Design Creativity was informed by an extensive and critically framed literature review. The model was also informed by insights from Grounded Theory analysis of published interviews and reflective writings of twenty eminent creative individuals and xi organizations that identified influential elements of creativity in art, architecture, and design creative practice. The Conceptual Model of Design Creativity informed the development of the Design Creativity Cards tool deployed in the empirical research. The cards were informed by creativity methods from cognitive psychology. The research employed both the tool and the model to frame the development of a design experimental study and the data analysis and findings. The purpose of the design experimental study is to investigate the role of the Design Creativity Cards in stimulating creative cognition. The experiment was conducted with thirty-one undergraduate and master-graduate students from three architecture and design schools. Participants from each school were divided into control and experimental groups and were engaged in a simple design task. The experimental groups were introduced to the Design Creativity Cards in a preliminary workshop and were then asked to use the cards during the design task. The data collected were analyzed in relation to seven divergent thinking abilities; the seventh ability of “ideation leap” emerged through analysis as a contribution from and of this research. The data were also analyzed in relation to the Conceptual Model of Design Creativity. The findings provide a proof of concept for the Conceptual Model of Design Creativity and the Design Creativity Cards tool that suggests support for their role in enhancing creative cognition.PH.D in Design, December 201

MAPbI3 Microrods-Based Photo Resistor Switches: Fabrication and Electrical Characterization

The current work proposed the application of methylammonium lead iodide (MAPbI3) perovskite microrods toward photo resistor switches. A metal-semiconductor-metal (MSM) configuration with a structure of silver-MAPbI3(rods)-silver (Ag/MAPbI3/Ag) based photo-resistor was fabricated. The MAPbI3 microrods were prepared by adopting a facile low-temperature solution process, and then an independent MAPbI3 microrod was employed to the two-terminal device. The morphological and elemental compositional studies of the fabricated MAPbI3 microrods were performed using FESEM and EDS, respectively. The voltage-dependent electrical behavior and electronic conduction mechanisms of the fabricated photo-resistors were studied using current–voltage (I–V) characteristics. Different conduction mechanisms were observed at different voltage ranges in dark and under illumination. In dark conditions, the conduction behavior was dominated by typical trap-controlled charge transport mechanisms within the investigated voltage range. However, under illumination, the carrier transport is dominated by the current photogenerated mechanism. This study could extend the promising application of perovskite microrods in photo-induced resistor switches and beyond

Metal halide-based photodetector using one-dimensional MAPbI3 micro rods

In the present work, we report the fabrication of a photodetector using methylammonium lead iodide perovskite (MAPbI3) micro rod. Photosensitivity of the Ag/MAPbI3/Ag photodetector has been studied under various light intensities ranging from 10 to 100 mW/cm2. The MAPbI3 perovskite micro rod-based photodetector shows a high on/off ratio (4.47 × 105), and fast response & recovery times (2.7 ms, each), as compared to the photodetectors using perovskite films. This work could initiate new perspectives for perovskite micro rods to be employed in high-performance optoelectronic devices.Other Information Published in: Journal of Materials Science: Materials in Electronics License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s10854-020-03757-1</p

A numerical approach to study the effect of bandgap and electron affinity in HTL-free perovskite solar cells and design of two-terminal silicon/perovskite tandem solar cell

The hole-transport layer (HTL) free perovskite solar cells with carbon electrode (c-PSCs) have garnered significant attention owing to their simple design, cost-effectiveness, and good stability. However, the power conversion efficiency (PCE) of these cells is still very low in comparison to conventional PSCs that utilize HTLs and metal electrodes. Tandem solar cells (TSCs) based on perovskite and crystalline silicon (c-Si) solar cells are considered possible contenders for surpassing the theoretical maximum limit and addressing the efficiency constraints encountered in single junction PSCs. The current research work assesses the design and optimization of a c-Si/c-PSC-based two-terminal (2-T) monolithically coupled TSC utilizing a one-dimensional solar cell capacitance simulator (SCAPS-1D) software. Initially, a detailed examination of standalone c-PSC has been conducted to evaluate bandgap and electron affinity variation. Then, the optimized c-PSC was integrated with the bottom c-Si cell by adopting a widely employed current matching technique. An investigation was undertaken to identify a current matching condition between two subcells that yielded optimal performance for the device. Under optimum conditions, a Voc of 2.138 V, Jsc of 15.60 mA/cm2, FF of 85.79%, and PCE of 28.62% were achieved in a 2-T monolithically connected tandem cell. We believe the results acquired in this study would be of significant importance in advancing highly efficient 2-T tandem cells based on HTL-free c-PSCs.The authors are solely responsible for the conclusions reached in this paper. In addition, the support from Prof. Marc Burgelman of the University of Gent in Belgium with the SCAPS software is highly acknowledged. This work was supported by the Qatar University Internal Grant (QUCG-YSC-23/24-217)

Ancient bone collagen assessment by hand-held vibrational spectroscopy

Radiometric, isotopic, proteomic, and genetic studies of bone collagen are mainstays of archaeometric analysis. All four techniques are destructive and require substantial laboratory, temporal, and financial commitments. Because such analyses are predicated on the presence of a sufficient quantity of unaltered proteins (i.e. collagen), the development and validation of tools for the rapid, non-destructive, in situ analysis of collagen content could yield measurable benefits. In the present work, the results of a preliminary, proof-of-concept study on the utility of four hand-held vibrational spectroscopic instruments, one Fourier-Transform Infrared (FTIR) spectrometer and three Raman spectrometers (two with an excitation wavelength of 785 nm, and one with an excitation wavelength of 1030 nm), for analyzing the collagen content of archaeological bones are described. While the FTIR and 785 nm Raman devices showed little or no ability to discriminate between well- and poorly-preserved bone, the application of hand-held 1030 nm Raman spectroscopy appears to be well-suited for such a task. The ability to detect a measurable and characteristic spectroscopic peak associated with the δCH2 scissoring of Type I collagen in high-yielding, raw bone samples opens the door to the utilization of this technology in field research environments. •Collagen content in ancient bone assessed by hand-held FTIR and Raman.•Goal is identification of field-deployable tools for sample triage.•FTIR and 785 nm Raman devices do not produce useful results.•1030 nm Raman differentiates between well- and poorly preserved collagen