STABILITY-INDICATING REVERSE-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR THE SIMULTANEOUS QUANTIFICATION OF APIGENIN AND LUTEOLIN FROM ACHILLEA MILLEFOLIUM LINN

Objective: A stability-indicating reverse-phase high-performance liquid chromatographic method was developed and validated for the analysis of apigenin and luteolin. The degradation behavior of apigenin and luteolin was investigated under different stress conditions as recommended by the International Conference on Harmonization (ICH). Methods: In the present study, a reversed-phase high-performance liquid chromatography method was developed and the resolution of the plant constituents was successfully achieved using Hibar Lichrospher C8 column with ultraviolet detector at a wavelength of 269 nm. The mobile phase consisted of methanol and 0.5% trifluoroacetic acid (80:20 v/v) at a flow rate of 1.0 ml/min. Both apigenin and luteolin were subjected to various stress degradation studies such as oxidation, acid and alkaline hydrolysis, and photolytic degradation. Results: The proposed method was found to be linear (1–5 μg/ml) with the linear correlation coefficient of R2=0.99. Although the degradation products of stressed conditions were not identified, the methods were able to detect the changes due to stress condition. Conclusion: The method provides good sensitivity and excellent precision and reproducibility. Forced degradation studies on apigenin and luteolin give information about their storage and intrinsic stability conditions considering the advanced pharmaceutical aspects of formulations

The Effect of Deposition Conditions on Heterointerface-Driven Band Alignment and Resistive Switching Properties

Titanium nitride and hafnium oxide stack have been widely used in various resistive memory elements since the materials are complementary-metal-oxide-semiconductor compatible. The understanding of the interface properties between the electrode and the oxide is important in designing the memory behavior. To bridge this understanding, HfOx grown using plasma enhanced atomic layer deposition (PEALD) and thermal atomic layer deposition (TALD) are compared, in terms of band alignment and electrical performances in the HfOx/PEALD TiN stacks. X-ray photoelectron spectroscopy reveals a thicker interfacial TiO2 layer in the PEALD HfOx/TiN stack whose interface resembles more to the PEALD HfOx/TiO2 interface (conduction band offset ΔEC = 1.63 eV), whereas the TALD HfOx stack interface resembles more to the TALD HfOx/TiN interface (ΔEC = 2.22 eV). The increase in the forming voltage and the early onset of reverse filament formation (RFF) in the I–V measurements for the PEALD HfOx stack confirms the presence of the thicker interfacial layer; the early onset of RFF is likely related to a smaller ΔEC. The findings show the importance of understanding the intricate details of the material stack, where ΔEC difference and the presence of a thicker TiO2 interfacial layer due to different deposition procedures affect the device performance

Raman mapping glucose metabolites during human mesenchymal stem cell adipogenesis

Raman mapping was used to determine the lipid distribution inside human mesenchymal stem cells during induced adipogenesis by monitoring C-H stretching bands of the fats inside the lipid droplets. By incorporating deuterated glucose into the cell culture medium during induction it was possible to distinguish whether or not downstream metabolites, either in lipid droplets or in the cytoplasm, had been formed before or after the adipogenic cascade, because C-D stretching bands are 1/√2 shifted compared to the C-H bands. Thus, metabolites formed after the initiation of the process displayed both C-H and C-D stretching bands and so were forming during induced adipogenesis rather than prior to it. With the ability to distinguish small putative lipid drops formed by the induction of adipogenesis from those pre-formed in the cell, it was possible to analyze spectral changes occurring in the droplets at the earliest stages of adipogenesis. There were two key findings. Firstly, Raman spectra of lipid droplets evolved over time, suggesting that their composition at the early stages was not the same as at the later stages. Secondly, it was apparent that the proportion of unsaturated fats in droplets was higher at early stages than it was at later stages, suggesting that unsaturated fats arrive in the droplets faster than saturated ones

Role of arbuscular mycorrhizal (Glomus intraradices) fungus inoculation on Zn nutrition in grains of field grown maize

Abstract Bioavailability of zinc (Zn) concentrations in maize grains is low causing malnutrition in humans. This study is aimed to use mycorrhizal fungal inoculation as one of the biological strategies to improve Zn concentrations in field grown maize. Treatments consisted of three levels of Zn (0, 2.5 and 5 kg Zn ha -1 ), two levels P (30 and 60 P kg ha -1 ) and two mycorrhizal fungal inoculation with (AMF+) and without arbuscular mycorrhizal (AMF-) fungus (Glomus intraradices Schenck & Smith) replicated three times in a FRBD. AMF+ plants had significantly (P ≤ 0.01) higher root length (AMF-16.8; AMF+ 23.5 cm) and volume, leaf area and chlorophyll concentrations regardless of P or Zn fertilization but the response to AMF inoculation was higher at lower levels of Zn fertilization. Maize grains of AMF+ plants had higher Zn and tryptophan concentrations by 15 and 8.6%, respectively, in comparison to AMF-plants. The plant available Zn concentration in soil had a highly significant correlation with Zn content in roots (r = 0.93), shoots (r = 0.91) and grains (r = 0.91). AMF symbiosis enhances Zn supply to the host plant by improving the available Zn and P enabling the plant to maintain higher nutritional status and produce grains fortified with Zn and tryptophan concentrations in field grown maize

Impact of deposition parameters on the material quality of SPC poly-Si thin films using high-rate PECVD of a-Si:H

The impact of the deposition parameters such as gas flow (sccm) and RF plasma power density (W/cm2) on the deposition rate of a-Si:H films is systematically investigated. A high deposition rate of up to 146 nm/min at 13.56 MHz is achieved for the a-Si:H films deposited with high lateral uniformity on 30 × 40 cm2 large-area glass substrates. A relationship between the SiH4 gas flow and the RF power density is established. The SiH4 gas flow to RF power density ratio of about 2.4 sccm/mW cm-2 is found to give a linear increase in the deposition rate. The influence of the deposition rate on the material quality is studied using UV-VIS-NIR spectrophotometer and Raman characterisation techniques. Poly-Si thin film with crystal quality as high as 90% of single-crystalline Si wafer is obtained from the SPC of high rate deposited a-Si:H films

Impact of deposition parameters on the material quality of SPC poly-Si thin films using high-rate PECVD of a-Si:H

The impact of the deposition parameters such as gas flow (sccm) and RF plasma power density (W/cm2) on the deposition rate of a-Si:H films is systematically investigated. A high deposition rate of up to 146 nm/min at 13.56 MHz is achieved for the a-Si:H films deposited with high lateral uniformity on 30 × 40 cm2 large-area glass substrates. A relationship between the SiH4 gas flow and the RF power density is established. The SiH4 gas flow to RF power density ratio of about 2.4 sccm/mW cm-2 is found to give a linear increase in the deposition rate. The influence of the deposition rate on the material quality is studied using UV-VIS-NIR spectrophotometer and Raman characterisation techniques. Poly-Si thin film with crystal quality as high as 90% of single-crystalline Si wafer is obtained from the SPC of high rate deposited a-Si:H films

New solid-state Eu(III)-containing metallo-supramolecular polymers: Morphology control and optical wave-guiding properties

© The Royal Society of Chemistry 2015.Herein, we report the solution phase self-assembly between Eu(iii) and a rigid ditopic tridentate terpyridine ligand which results in the formation of supramolecular metallo-networks in the solid state. Depending on the ligand to metal ratio used for the initial self-assembly process, the morphology of these materials can be altered from one-dimensional micron-sized fibres to a three-dimensional coordination network. The terpyridine-based ditopic ligand can act as an efficient sensitizer for Eu(iii) emission whereby the emission lifetimes and ligand triplet state energies of the metallo-polymers strongly depend on the ligand to metal ratio. The obtained micron-sized fibres can act as an efficient optical wave-guide for Eu(iii) emission.Link_to_subscribed_fulltex

Charge generation and recombination in diketopyrrolopyrrole polymer: Fullerene bulk heterojunctions studied by transient absorption and time-resolved microwave conductivity

Charge generation and recombination dynamics in organic photovoltaic bulk heterojunction films comprising the donor polymer, PDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-naphthalene}), blended with the fullerene acceptor, PC71BM ([6,6]-phenyl C71-butyric acid methyl ester), have been studied. The charge-carrier generation process was studied using femtosecond transient absorption, and it was found that the efficiency of charge generation is not dominated by geminate recombination but rather is limited by exciton diffusion in the films. Highly sensitive nanosecond transient absorption (ns-TA) and time-resolved microwave conductivity (TRMC) were used to study charge recombination. From ns-TA measurements, we obtained a recombination rate constant of 1 × 10–9 cm3 s–1 and found that charge recombination is limited by the diffusion of charge carriers (Langevin-type recombination). TRMC signals were comparable with ns-TA on shorter time scales. However, in contrast with ns-TA, the TRMC signal contained an additional long-lived component. The fast decay on shorter time scales is attributed to the recombination of the majority of the charge carriers. The long-lived component is assigned to a small population of charge carriers with high mobility, suggesting they are located in isolated, crystalline domains within the bulk heterojunction. These findings are discussed in relation to the morphology of the blend film, fluorescence quenching properties, and device performance including photoinduced charge extraction by linearly increasing voltage (PhotoCELIV) measurements described in our previous publications

Design, preparation and assessment of surface-immobilised tetraphenylethenes for biosensing applications

Tetraphenylethene (TPE) shows a significant increase of fluorescence intensity when the rotational free-dom of its phenyl groups is restricted. This special property allows the use of TPE in sensor applications,which have been previously described for the liquid phase only. However, some applications utilisingarrays require the immobilisation of TPE dyes on solid surfaces. In this work, we synthesised and investi-gated the fluorescence behaviour of TPE derivatives on silica particles and quartz slides and suggest waysto employ the dye’s properties in solid phase biosensor applications

The Foliar Application of Rice Phyllosphere Bacteria induces Drought-Stress Tolerance in <i>Oryza sativa</i> (L.)

This study assessed the potential of Bacillus endophyticus PB3, Bacillus altitudinis PB46, and Bacillus megaterium PB50 to induce drought tolerance in a susceptible rice cultivar. The leaves of the potted rice plants subjected to physical drought stress for 10 days during the flowering stage were inoculated with single-strain suspensions. Control pots of irrigated and drought-stressed plants were included in the experiment for comparison. In all treatments, the plant stress-related physiochemical and biochemical changes were examined and the expression of six stress-responsive genes in rice leaves was evaluated. The colonization potential on the surface of the rice leaves and stomata of the most successful strain in terms of induced tolerance was confirmed in the gnotobiotic experiment. The plants sprayed with B. megaterium PB50 showed an elevated stress tolerance based on their higher relative water content and increased contents of total sugars, proteins, proline, phenolics, potassium, calcium, abscisic acid, and indole acetic acid, as well as a high expression of stress-related genes (LEA, RAB16B, HSP70, SNAC1, and bZIP23). Moreover, this strain improved yield parameters compared to other treatments and also confirmed its leaf surface colonization. Overall, this study indicates that the foliar application of B. megaterium PB50 can induce tolerance to drought stress in rice