The spin-polarized second harmonic generation (SHG) of the recently synthesized CaCoSO single crystal is performed based on the calculated electronic band structure. The calculation reveals that the spin-up (↑) channel of CaCoSO possesses a direct energy gap (Γv-Γc) of about 2.187 eV, 1.187 eV (Kv-Kc) for the spin-down (↓) channel and an indirect gap (Γv-Kc) of about 0.4 eV for the spin-polarized CaCoSO single crystal. The linear optical properties obtained reveal that the recently synthesized crystal exhibits considerable anisotropy with negative uniaxial anisotropy and birefringence favor to enhance the SHG. We have calculated the three non-zero tensor components of the SHG and found the is the dominat component, one with a large SHG of about (d33 = 6.936 pm/V at λ = 1064 nm), the half value of KTiOPO4 (KTP). As the values of (↑) (↓) 1.187 eV> spin-polarized gap 0.4 eV; therefore, a smaller energy gap gives better SHG performance. Furthermore, the microscopic first hyperpolarizability, βijk, is calculated.
We report the development of the C3N4 structure by integrating two different structures: (i) two identical layers as AA-stacked C3N4 and (ii) intercalating one different layer between two identical layers as ABA-stacked C3N4. This in turn endows C3N4 with significantly promoted charge migration, up-shifted conduction-band (CB) level, enhanced CB potential from -0.89 eV (AA-stacked C3N4) to -1.03 eV (ABA-stacked C3N4), broadened band gap as well as enhanced surface area, all of which favor the enhancement of the photocatalytic performance. The optical absorption level exhibited significant enhancement in the visible light region when shifting from AA-stacked C3N4 to ABA-stacked C3N4, where the absorption edge moves from λ = 508.1 → λ = 454.1 nm. This corresponds to the direct optical band gap of 2.44 eV → 2.73 eV, which is well matched with the solar spectrum and the sufficient negative CB potential for H+/H2 reduction. Based on these results, we can conclude that AA-stacked and ABA-stacked C3N4 satisfies all the requirements to be efficient photocatalysts. This study will significantly improve the search efficiency and considerably aid the experimentalists in the exploration of novel photocatalysts.
The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO3:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.
Mammalian adipose tissue derived stem cells (AT-SC) have a tremendous potential in regenerative medicine for tissue engineering and somatic nuclear transfer (SNT). The isolation methods of human and bovine adipose tissue derived stem cells are compared in this paper to determine the feasibility and optimum method of isolation. The optimum isolation method will reduce the processing time, efforts and money as isolation is the first crucial and important step in stem cells research. Human abdominal subcutaneous adipose tissue and bovine abdominal subcutaneous adipose tissue are digested in three collagenase type 1 concentration 0.075%, 0.3% and 0.6% agitated at 1 h and 2 h under 37 °C in 5% CO2 incubator. The cultures are then morphologically characterised. Human adipose tissue stem cells are found to be best isolated using abdominal subcutaneous depot, using 0.075% collagenase type 1 agitated at 1 h under 37 °C in CO2 incubator. While bovine adipose tissue derived stem cells are best isolated using abdominal subcutaneous depot, using 0.6% collagenase type 1 agitated at 2 h under 37 °C in CO2 incubator.
The potential of organic semiconductor based devices for light generation is demonstrated by the commercialisation of display technologies using organic light emitting diode (OLED). In OLED, organic materials plays an important role of emitting light once the current is passed through. However OLED have drawbacks whereby it suffers from photon loss and exciton quenching. Organic light emitting transistor (OLET) emerged as a new technology to compensate the efficiency and brightness loss encountered in OLED. The structure has combinational capability to switch the electronic signal such as the field effect transistor (FET) as well as to generate light. Different colours of light could be generated by using different types of organic material. The light emission could also be tuned and scanned in OLET. The studies carried out in this paper focuses on investigation of fabricated MEH-PPV based OLED and also OLET via current voltage characteristics. These studies will continue with a view to develop an optimised MEH-PPV based OLET.
Novel self-activated yellow-emitting BaLuAlxZn4-xO7-(1-x)/2 photoluminescent materials were investigated by a combined experimental and theoretical analysis. The effects of Al/Zn composition modulation, calcination atmosphere and temperature on the crystal structure and photoluminescence properties have been studied via engineering oxygen vacancies. Accordingly, BaLuAl0.91Zn3.09O7 prepared in an air atmosphere was found to be the stable crystalline phase with optimal oxygen content and gave a broad yellow emission band with a maximum at 528 nm. The self-activated luminescence mechanism is ascribed to the O-vacancies based on the density functional theory (DFT) calculation. A theoretical model originating from the designed oxygen vacancies has been proposed in order to determine the influence of O-vacancies on the band structure and self-activated luminescence. Therefore, the appearance of a new local energy level in the band gap will cause the wide-band optical transitions in the studied BaLuAlxZn4-xO7-(1-x)/2 materials.
Full Heuslers alloys are a fascinating class of materials leading to many technological applications. These have been studied widely under ambient conditions. However, less attention been paid to study them under the effect of compression and strain. Here in this work Co2YZ (Y= Cr, Nb, Ta, V and Z = Al, Ga) Heusler alloys have been studied comprehensively under pressure variations. Calculated lattice constants are in reasonable agreement with the available data. It is determined that lattice constant deceases with the increase in tensile stress and increases by increasing pressure in reverse direction. Band profiles reveals the half metallic nature of the studied compounds. The bond length decreases while band gap increases in compressive strain. The compounds are found to be reflective in visible region, as characteristics of the metals. The magnetic moments reveal the half-mettalic ferromagnetic nature of the compounds.
Breast cancer is one of the most reported cancers that can lead to death. Despite the advances in diagnosis and treatment procedures, the possibility of cancer recurrences is still high in many cases. With that in consideration, researchers from all over the world are showing interest in the unique features of Graphene oxide (GO), such as its excellent and versatile physicochemical properties, to explore further its potential and benefits towards breast cancer cell treatment. In this study, the cell viability and electrical response of GO, in terms of resistivity and impedance towards the breast cancer cells (MCF7) and normal breast cells (MCF10a), were investigated by varying the pH and concentration of GO. Firstly, the numbers of MCF7 and MCF10a were measured after being treated with GO for 24 and 48 h. Next, the electrical responses of these cells were evaluated by using interdigitated gold electrodes (IDEs) that are connected to an LCR meter. Based on the results obtained, as the pH of GO increased from pH 5 to pH 7, the number of viable MCF7 cells decreased while the number of viable MCF10a slightly increased after the incubation period of 48 h. Similarly, the MCF7 also experienced higher cytotoxicity effects when treated with GO concentrations of more than 25 µg/mL. The findings from the electrical characterization of the cells observed that the number of viable cells has corresponded to the impedance of the cells. The electrical impedance of MCF7 decreased as the number of highly insulating viable cell membranes decreased. But in contrast, the electrical impedance of MCF10a increased as the number of highly insulating viable cell membranes increased. Hence, it can be deduced that the GO with higher pH and concentration influence the MCF7 cancer cell line and MCF10a normal breast cell.
Cs2Pb(MoO4)2crystals were prepared by crystallization from their own melt, and the crystal structure has been studied in detail. At 296 K, the molybdate crystallizes in the low-temperature α-form and has a monoclinic palmierite-related superstructure (space group C2/m, a = 2.13755(13) nm, b = 1.23123(8) nm, c = 1.68024(10) nm, β = 115.037(2)°, Z = 16) possessing the largest unit cell volume, 4.0066(4) nm3, among lead-containing palmierites. The compound undergoes a distortive phase transition at 635 K and incongruently melts at 943 K. The electronic structure of α-Cs2Pb(MoO4)2was explored by using X-ray emission spectroscopy (XES) and X-ray photoelectron spectroscopy methods. For α-Cs2Pb(MoO4)2, the photoelectron core-level and valence-band spectra and the XES band representing the energy distribution of Mo 4d and O 2p states were recorded. Our results allow one to conclude that the Mo 4d and O 2p states contribute mainly to the central part and at the top of the valence band, respectively, with also significant contributions throughout the whole valence-band region of the molybdate under consideration.