Quantum Chemical Simulation of Molecular Structures for High Efficiency Solar Cells

Organic fluorophores are important component in the present day optical and photo electronic devices such as displays, solar cells, light emitting diodes, etc due to several characteristics including large choice of emission and absorption wavelengths window, high absorption cross section, and possibility of synthesizing them from abundant renewable sources. Various dyes such as xanthenes, azo, porphyrins,indolines, Ru complex dyes are evaluated for the above applications. Among them, renewable energy devices under the photovoltaic protocol have become particularly interesting due to its potential to be fabricated at lower cost. Dyes are the important component of dye-sensitized solar cells (DSSCs), in which the dyes are the primary absorbers of solar energy. Upon light excitation, the photoexcited electrons in the dyes are injected to a metal oxide semiconducting nanostructure from where it is collected. A large choice of dyes is tested for the DSC application; however, the state-of the-art DSC employs a porphyrin dye conjugated to mesoporous TiO particles. Photovoltaic conversion efficiency as high as ~12% and open voltage above 1 V has been typically achieved in DSCs employing porphyrin dyes in mesoporousTiO 22 andCuI/ tri iodide electrolyte. Compared to the conventional ruthenium based bypyridyl dicarboxylic acid dyes, porphyrin dyes are attractive because of their low cost and extended absorption wavelength window. A survey of literature shows that there are little study on understanding deeply the structure and properties of porphyrin dyes using quantum chemical methods. We studied the properties of different prophyrin dyes to enhance the efficiency of DSSC using ab-initio quantum chemical methods. Quantum chemical calculations under the framework of DFT were employed to study the difference in ground and excited state properties of porphyrin dyes. DFT calculations were performed with the use of Becke’s three parameter hybrid methods [Becke, 1993] with the Lee, Yang and Parr (B3LYP) gradient corrected correlation functional [Lee et al., 2008] using the Gaussian 09W program packages [Frisch, et al., 2009].Geometry optimizations were carried out using the standard double-ζ quality lanl2dz basis sets [Hay and Wadt, 1985] followed by harmonic frequency calculations and simulating their IR spectra. Discrete spectra of excitation energies and corresponding oscillator strengths were obtained by the time-dependent DFT (TDDFT) method including energy singlet transitions [Scalmani, et al., 2006]. Molecular volumesof molecules were obtained from the Gaussian output file of the optimized geometry. Additional TDDFT single point energy calculation is used to map the electron density of the ground and excited states of the dyes. The porphyrin molecules were modeled with and without Zn as central atom and phenyl groups as a meso substituent. Fig.1a summarizes the results of the calculations. Porphyrin, Zn porphyrin complex,tetraphenyl porphyrin, and tetraphenyl Zn porphyrin complex were considered in this study. All these molecules were experimentally found in literature. The reliability of the optimized geometry was further checked by harmonic frequency calculations at the B3LYP/lanl2dz level of DFT. The simulated IR spectrum of the optimized structure showed only real frequencies thereby confirming a minimum energy structure. Absorption wavelength windows and oscillator strengths of these dyes were obtained by the time-dependent DFT (TDDFT) method. UV-Vis spectrum show light absorption range is almost from 200-600, shown in fig 1b

Ta’dīb and its implementation in children’s education, an analytical study from the prophetic hadīth

The study aims to explore the concept of the ta’dīb (discipline) of children and the way parents and teachers discipline children from the perspective of Sunnah. It attempts to examine the social structure of muslim families, which instils in children some Islamic values and traditional standards. It is agreed that this violent approach does not align with Prophet Muhammad’s approach to disciplining children. It employs inductive and analytical methodologies in which relevant data is collected from Sunnah books (Kutub Sittah) to guide the ta’dīb concept and its application in child education. However, its use in the Sunnah stands unequivocally for discipline. Secondly, corporal punishment has hardly any relevance to the concept of ta’dīb except in exceptional cases. Third, prophetic principles of raising children according to ta’dīb include behavioural modification; developing self-esteem; motivation for seeking knowledge; the impact of naming children; learning through play; self-evaluation; and education through emotional intelligence and compassion. These multiple outcomes are expected to be beneficial in dealing with children’s welfare. Hence, the concept of ta’dīb, if defined and practised properly, can be applied to disciplining children as an Islamic methodology of children’s education, positively and politely

N-(2-Hy­droxy-1,1-dimethyl­eth­yl)-4-methyl­benzene­sulfonamide

In the title mol­ecule, C11H17NO3S, the S atom has a distorted tetra­hedral geometry [maximum deviation: O—S—O = 119.08 (9)°]. In the crystal, mol­ecules are connected by inter­molecular N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds, forming layers of mol­ecules aligned parallel to (110). The 2-methyl­propan-1-ol group of the mol­ecule is disordered over two positions with an 0.592 (4):0.408 (4) occupancy ratio

Heat Transfer Attributes of Gold–Silver–Blood Hybrid Nanomaterial Flow in an EMHD Peristaltic Channel with Activation Energy

The heat enhancement in hybrid nanofluid flow through the peristaltic mechanism has received great attention due to its occurrence in many engineering and biomedical systems, such as flow through canals, the cavity flow model and biomedicine. Therefore, the aim of the current study was to discuss the hybrid nanofluid flow in a symmetric peristaltic channel with diverse effects, such as electromagnetohydrodynamics (EMHD), activation energy, gyrotactic microorganisms and solar radiation. The equations governing this motion were simplified under the approximations of a low Reynolds number (LRN), a long wavelength (LWL) and Debye–Hückel linearization (DHL). The numerical solutions for the non-dimensional system of equations were tackled using the com-putational software Mathematica. The influences of diverse physical parameters on the flow and thermal characteristics were computed through pictorial interpretations. It was concluded from the results that the thermophoresis parameter and Grashof number increased the hybrid nanofluid velocity near the right wall. The nanoparticle temperature decreased with the radiation parameter and Schmidt number. The activation energy and radiation enhanced the nanoparticle volume fraction, and motile microorganisms decreased with an increase in the Peclet number and Schmidt number. The applications of the current investigation include chyme flow in the gastrointestinal tract, the control of blood flow during surgery by altering the magnetic field and novel drug delivery systems in pharmacological engineering.This work was supported by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia (Project No. AN00052)

Pfibrolizer: A new paradigm for large scale electrospinning from lessons learnt from Malaysian kitchen

Electrospinning is a fiber production method, in which a liquid droplet is electrified to generate a jet, followed by stretching and elongation to generate fibers. Electrospinning setup mainly consists of 3 parts, a spinneret, high voltage source and a collector. The currently available electrospinning spinneret in markets has several drawbacks which limits its efficiency. Inspired from the Malaysian kitchen, we have designed a simple electrospinning spinneret head which is beneficial for large scale nanofiber production. This design also allows the user to easily modify the spinneret according to the requirements of morphology and number of fibers

Effective extraction of cephalosporin C from whole fermentation broth of Acremonium chrysogenum utilizing aqueous two phase systems

The downstream processing of biotechnological products from fermentation broth is an important step of production and development of cost effective, efficient downstream processing of many biotechnological products. The present study was conducted by employing aqueous two phase systems (ATPSs) for the extraction of cephalosporin C (CPC) from whole fermentation broth of Acremonium chrysogenum. The biphasic system was prepared by mixing equal aliquots of 15% w/w polyethylene glycol (PEG) 3350 with 15% (NH4)2SO4. The effects of pH, neutral salts, temperature and centrifugal force on partitioning in ATPS to develop efficient extraction system for recovery of CPC from fermentation broth were also examined. The extraction efficiency was improved by enhancing the centrifugal force. Similarly centrifugation for 12.5 min also gave the maximum extraction. Improvement in the recovery yield was also observed by the addition of 0.1% NaCl. The concentration of CPC was determined by high performance liquid chromatography (HPLC). Slight modifications in the mobile phase from 10 to 5% MeOH improved CPC resolution. Further development of more inexpensive systems for extraction can be the future target of research.Keywords: Cephalosporin C, Acremonium chrysogenum, fermentation, aqueous two phase system (ATPS

Promising potential of electro-coagulation process for effective treatment of biotreated palm oil mill effluents

The critical parameters namely initial pH, time and current density largely impact the process efficiency of electrocoagulation (EC). Few works have been done on observing the interaction of these critical parameters and the possible combined effect on the overall pollutant removal efficiency. Therefore, the knowledge of the combined effect of critical parameter interaction would enhance the optimization of EC parameters to attain maximum efficiency with limited resources. Using aluminium electrodes with interelectrode distance of 10 mm on synthetic wastewater, representing biotreated palm oil mill effluent (BPOME), with a set range of initial pH, current density, and time of 3-8, 40-160 mA/cm2 and 15 to 60 minutes, respectively, the effect of the three critical variables was investigated. The optimum Chemical Oxygen Demand (COD) removal of 71.5% was determined at pH 6, current density of 160 mA/cm2 (with current 1.75 A) at EC time of 15 minutes. The experiment was validated with real BPOME, resulting in the removal efficiency of 60.7 % COD, 99.91 % turbidity, 100 % total suspended solids (TSS) and 95.7 % colour. Removal of a large quantity of pollutants in a time span of 15 minutes with optimized parameters in EC is notable for a wastewater treatment alternative that requires no extensive use of chemicals. The interaction of parameters observed in this study indicated a synergistic contribution of initial pH and current density in removing maximum wastewater COD in 15 minutes of EC

Lithium-ion adsorption on surface modified porous carbon

Lithium-ion storage in porous carbon electrodes offers challenges due to poor electrode kinetics and limited storability. In this article, we demonstrate improved lithium-ion storage kinetics and rate capability in carbon electrode with appropriate surface or void modifications. The surface of porous carbon is modified by developing a thin film of either a metal oxide (Mn2O3) or a metal (cobalt) or the large voids in them are filled using hierarchical MnCo2O4 or TiO2 nanoflowers. Lithium-ion capacitors are fabricated in the Carbon//LiPF6//Li configuration and evaluated their lithium storage performance using cyclic voltammetry, galvanostatic charge discharge cycling, and electrochemical impedance spectroscopy. While the surface or void modification nominally increased the specific capacitance, the potential window and rate capability of the resulting devices remarkably increased. Among all the tested devices, the MnCo2O4 flowers filled electrode showed the largest capacitance and capacity retention, which are ascribed to its lower lithium transfer resistance

Tailoring the charge storability of commercial activated carbon through surface treatment

Sustainability concerns in the electrochemical charge storage realm revitalized research on the electrochemical capacitors (ECs), or synonymously, supercapacitors (SCs), because of the renewability of their electrode materials and environmental benignity thereby, longer life cycle to improve materials circularity, and their inherent superior rate charging/discharging than batteries. As SCs store energy via the reversible adsorption of electrolyte ions on the electrode pores, maximizing the number of pores to accommodate the ions is the most desired way to improve the charge storability. In this regard, we report herewith a simple and facile approach for engineering the porosity of commercial activated carbon by refluxing it in nitric acid as a function of time; the BET surface area of the 72 h refluxed samples increased by 75 %. Charge storage properties of the modified electrodes are evaluated in a three-electrode system configuration in 1 M Na2SO4 electrolyte; a 75 % increase in the surface area led to an increase in specific capacitance over 110 % following a significant reduction in Warburg impedance. Besides, symmetric SC full cells were fabricated by varying the electrode mass between 3 and 14 mg·cm−2 in five steps. All the fabricated devices achieved a potential window of 1.8 V in 1 M Na2SO4. The highest mass loaded (∼14 mg·cm−2) device fabricated using the prepared material has delivered a maximum capacitance of ∼990 mF, the maximum areal capacitance of ∼494 mF·cm−2, an energy density of ∼13 mWh·cm−3, and a maximum power density of ∼2189 mW·cm−3. The device also maintained ∼97 % retention in capacitance with a remarkable coulombic efficiency of ∼97 % after 5000 cycles. The performance of the device is comparable with the commercial SCs used for low voltage DC hold-up applications such as embedded microprocessor systems. The procedure developed herewith supports easy recycling and reusing of the activation agent, and thereby reduces the release of toxic chemicals into the environment

Curcumin loaded waste biomass resourced cellulosic nanofiber cloth as a potential scaffold for regenerative medicine: An in-vitro assessment

This article demonstrates the development of nanofibrous cloths by electrospinning of renewable materials, i.e., curcumin-loaded 90% cellulose acetate (CA)/10% poly(ε-caprolactone) (PCL), for applications in regenerative medicine. The CA is derived from the biomass waste of the oil palm plantation (empty fruit bunch). The nanofiber scaffolds are characterized for the fiber morphology, microstructure, thermal properties, and wettability. The optimized smooth and bead-free electrospun fiber cloth contains 90% CA and 10% PCL in two curcumin compositions (0.5 and 1 wt%). The role of curcumin is shown to be two-fold: the first is its function as a drug and the second is its role in lowering the water contact angle and increasing the hydrophilicity. The hydrophilicity enhancements are related to the hydrogen bonding between the components. The enhanced hydrophilicity contributed to improve the swelling behavior of the scaffolds; the CA/PCL/Cur (0.5%) and the CA/PCL/Cur (1.0%) showed swelling of ~700 and 950%, respectively, in phosphate-buffered saline (PBS). The drug-release studies revealed the highest cumulative drug release of 60% and 78% for CA/PCL/Cur (0.5%) and CA/PCL/Cur (1.0%) nanofibers, respectively. The in-vitro studies showed that CA/PCL/Cur (0.5 wt%) and CA/PCL/Cur (1.0 wt%) nanofiber scaffolds facilitate a higher proliferation and expression of actin in fibroblasts than those scaffolds without curcumin for wound healing applications