Simultaneous analysis of diosgenin and sarsasapogenin in Asparagus officinalis byproduct by thin‐layer chromatography

Introduction – Asparagus officinalis L. has several biological activities including antifungal, antiviral and antitumoral activities due to the steroidal saponins. Normally diosgenin and sarsasapogenin are analysed separately by thin‐layer chromatography or high‐performance liquid chromatography (HPLC‐UV or HPLC‐ELSD), which is time‐consuming and expensive, so we need to find a rapid solution to this problem. Objective – To develop a sensitive, rapid and validated TLC method for simultaneous detection and quantification of diosgenin and sarsasapogenin. Methodology – Samples were prepared by extraction of A. officinalis with 70% aqueous ethanol to get steroidal saponins, and then hydrolysed using 36 mL 2 m hydrochloric acid for 3 h. The hydrolysis product was extracted with chloroform, and then analysed by TLC, the results of which were verified by HPLC and HPLC‐MS. Results – The retention factor (R_f) of diosgenin and sarsasapogenin on TLC plate were 0.49 and 0.6, respectively. After calculation from the regression equation of the standard curve, the contents of diosgenin and sarsasapogenin in the A. officinalis extract were 0.27–0.46 and 0.11–0.32%, respectively. Conclusion – The study showed that thin‐layer chromatography can be applied for the determination of diosgenin and sarsasapogenin in the oldest tissue of A. officinalis, and also can be conducted for screening of sapogenin in other plant or extracts. Copyright © 2010 John Wiley & Sons, Ltd.     

Design of experiment assisted concurrent enantioseparation of bupropion and hydroxybupropion by high‐performance thin‐layer chromatography

A simple and efficient high‐performance thin‐layer chromatographic method was developed for chiral separation of rac ‐bupropion (BUP) and its active metabolite rac ‐hydroxybupropion (HBUP). Design of experiment (DoE)‐based optimization was adopted instead of a conventional trial‐and‐error approach. The Box–Behnken design surface response model was used and the operating variables were optimized based on 17 trials design. The optimized method involved impregnation of chiral reagent, L(+)‐tartaric acid, in the stationary phase with simultaneous addition in the mobile phase, which consisted of acetonitrile : methanol : dichloromethane : 0.50% L‐tartaric acid (6.75:1.0:1.0:0.25, v /v /v /v ). Under the optimized conditions, the resolution factor between the enantiomers of BUP and HBUP was 6.30 and 9.26, respectively. The limit of detection and limit of quantitation for (R)‐BUP, (S)‐BUP, (R,R)‐HBUP, and (S,S)‐HBUP were 9.23 and 30.78 ng spot⁻¹, 10.32 and 34.40 ng spot⁻¹, 12.19 and 40.65 ng spot⁻¹, and 14.26 and 47.53 ng spot⁻¹, respectively. The interaction of L‐tartaric acid with analytes and their retention behavior was thermodynamically investigated using van't Hoff's plots. The developed method was validated as per the International Conference on Harmonization guidelines. Finally, the method was successfully applied to resolve and quantify the enantiomeric content from marketed tablets as well as spiked plasma samples.     

Development of chromatographic and free radical scavenging activity fingerprints by thin‐layer chromatography for selected Salvia species

Introduction – Plant‐derived free radical scavengers have become the subject of intensive scientific interest. Recently, the concept of coupling chromatographic fingerprints with biological fingerprinting analysis has gained much attention for the quality control of plant extracts. However, identification of free radical scavenging activity of each single compound in a complex mixture is a difficult task. Thin‐layer chromatography with post‐chromatographic derivatisation with the methanol solution of DPPH can be a valuable tool in such analyses. Objective – Development of chromatographic and free radical scavenging fingerprints of nineteen Salvia species grown and cultivated in Poland. Methodology – Chromatography was performed on the silica gel layers with use of two eluents, one for the resolution of the less polar compounds, and the other one for the resolution of the medium and highly polar ones. The plates were sprayed with the vanillin–sulfuric acid reagent to produce chemical fingerprints, and with DPPH solution to generate free radical scavenging fingerprints. Results – With four Salvia species, it was revealed that their strong free radical scavenging properties are not only due to the presence of polar flavonoids and phenolic acids, but also due to the presence of several free radical scavengers in the less polar fraction. Because of the similarities in both the chromatographic and the free radical scavenging fingerprints, S. triloba can be introduced as a possible equivalent of the pharmacopoeial species, S. officinalis. Conclusion – Fingerprints developed in the experiments proved useful for the analysis of complex extracts of the different Salvia species. Copyright © 2010 John Wiley & Sons, Ltd.     

A Low‐Temperature Thin‐Film Encapsulation for Enhanced Stability of a Highly Efficient Perovskite Solar Cell

The stability of a perovskite solar cell (PSC) is enhanced significantly by applying a customized thin‐film encapsulation (TFE). The TFE is composed of a multilayer stack of organic/inorganic layers deposited by initiated chemical vapor deposition and atomic layer deposition, respectively, whose water vapor transmission rate is on the order of 10^?4 g m^?2 d^?1 at an accelerated condition of 38 °C and 90% relative humidity (RH). The TFE is optimized, taking into consideration various aspects of thermosensitive PSCs. Lowering the process temperature is one of the most effective methods for minimizing the thermal damage to the PSC during the monolithic integration of the TFE onto PSC. The direct deposition of TFE onto a PSC causes less than 0.3% degradation (from 18.5% to 18.2%) in the power conversion efficiency, while the long‐term stability is substantially improved; the PSC retains 97% of its original efficiency after a 300 h exposure to an accelerated condition of 50 °C and 50% RH, confirming the enhanced stability of the PSC against moisture. This is the first demonstration of a TFE applied directly onto PSCs in a damage‐free manner, which will be a powerful tool for the development of highly stable PSCs with high efficiency.     

Rapid Identification of Rice Samples Using an Electronic Nose

Four rice samples of long grain type were tested using an electronic nose (Cyranose-320).Samples of 5 g of each variety ofrice were placed individually in vials and were analyzed with the electronic nose unit consisting of 32 polymer sensors.TheCyranose-320 was able to differentiate between varieties of rice.The chemical composition of the rice odors for differentiatingrice samples needs to be investigated.The optimum parameter settings should be considered during the Cyranose-320 trainingprocess especially for multiple samples,which are helpful for obtaining an accurate training model to improve identificationcapability.Further,it is necessary to investigate the E-nose sensor selection for obtaining better classification accuracy.A re-duced number of sensors could potentially shorten the data processing time,and could be used to establish an application pro-cedure and reduce the cost for a specific electronic nose.Further research is needed for developing analytical procedures thatadapt the Cyranose-320 as a tool for testing rice quality.     

薄层色谱法鉴定天麻胶囊中的天麻素

为了建立天麻胶囊中主要有效成分天麻素的快速鉴定方法,根据天麻素的理化特性,使用乙醇和甲醇提取天麻胶囊中的天麻素,使用薄层色谱法进行鉴定,并与高效液相色谱法的分析结果进行比较。结果表明,薄层色谱法的鉴定结果与高效液相色谱法的检测结果一致,能较准确地鉴别天麻胶囊的真伪。本研究结果表明薄层色谱法能快速简便、准确灵敏地检测天麻胶囊中的有效成分,可作为法定鉴定方法的补充,对天麻胶囊实施快速初筛。     

Pseudo‐real‐time retinal layer segmentation for high‐resolution adaptive optics optical coherence tomography

We present a pseudo‐real‐time retinal layer segmentation for high‐resolution Sensorless Adaptive Optics‐Optical Coherence Tomography (SAO‐OCT). Our pseudo‐real‐time segmentation method is based on Dijkstra's algorithm that uses the intensity of pixels and the vertical gradient of the image to find the minimum cost in a geometric graph formulation within a limited search region. It segments six retinal layer boundaries in an iterative process according to their order of prominence. The segmentation time is strongly correlated to the number of retinal layers to be segmented. Our program permits en face images to be extracted during data acquisition to guide the depth specific focus control and depth dependent aberration correction for high‐resolution SAO‐OCT systems. The average processing times for our entire pipeline for segmenting six layers in a retinal B‐scan of 496 × 400 and 240 × 400 pixels are around 25.60 and 13.76 ms, respectively. When reducing the number of layers segmented to only two layers, the time required for a 240 × 400 pixel image is 8.26 ms.     

Characterizing the S‐layer structure and anti‐S‐layer antibody recognition on intact Tannerella forsythia cells by scanning probe microscopy and small angle X‐ray scattering

Tannerella forsythia is among the most potent triggers of periodontal diseases, and approaches to understand underlying mechanisms are currently intensively pursued. A ~22‐nm‐thick, 2D crystalline surface (S‐) layer that completely covers Tannerella forsythia cells is crucially involved in the bacterium–host cross‐talk. The S‐layer is composed of two intercalating glycoproteins (TfsA‐GP, TfsB‐GP) that are aligned into a periodic lattice. To characterize this unique S‐layer structure at the nanometer scale directly on intact T. forsythia cells, three complementary methods, i.e., small‐angle X‐ray scattering (SAXS), atomic force microscopy (AFM), and single‐molecular force spectroscopy (SMFS), were applied. SAXS served as a difference method using signals from wild‐type and S‐layer‐deficient cells for data evaluation, revealing two possible models for the assembly of the glycoproteins. Direct high‐resolution imaging of the outer surface of T. forsythia wild‐type cells by AFM revealed a p4 structure with a lattice constant of ~9.0 nm. In contrast, on mutant cells, no periodic lattice could be visualized. Additionally, SMFS was used to probe specific interaction forces between an anti‐TfsA antibody coupled to the AFM tip and the S‐layer as present on T. forsythia wild‐type and mutant cells, displaying TfsA‐GP alone. Unbinding forces between the antibody and wild‐type cells were greater than with mutant cells. This indicated that the TfsA‐GP is not so strongly attached to the mutant cell surface when the co‐assembling TfsB‐GP is missing. Altogether, the data gained from SAXS, AFM, and SMFS confirm the current model of the S‐layer architecture with two intercalating S‐layer glycoproteins and TfsA‐GP being mainly outwardly oriented. Copyright © 2013 John Wiley & Sons, Ltd.     

Use of TLC‐FID and GC‐MS/FID to examine the effects of migratory state,diet and captivity on preen wax composition in White‐throated Sparrows Zonotrichia albicollis

Preen wax is important for plumage maintenance and other functions. Its chemical composition is complex, and separating and quantifying its components, commonly by gas chromatography (GC), can be challenging. We present a simple analytical system consisting of thin‐layer chromatography/flame ionization detection (TLC‐FID) using a solvent system of 100% toluene to analyse the complex compound classes present in preen wax. We used GC and TLC‐FID to investigate the effects of migratory status, diet and captivity on the preen wax composition of White‐throated Sparrows Zonotrichia albicollis, and to measure the quantity of preen wax on the head, primary and tail feathers. White‐throated Sparrows produced preen wax containing only monoesters regardless of migratory state. The monoesters contained several isomers consisting of homologous series of fatty alcohols (C10–C20) and fatty acids (C13–C19) esterified together in different combinations to form monoesters with total carbon numbers ranging from C23 to C38. Weighted average monoester carbon number was greater in captive birds than in wild birds and was greater in captives fed a formulated diet enriched with sesame oil than in birds fed the same diet enriched with fish oil. Captivity and migratory state also affected the complexity of the mixture of monoesters. There was significantly more preen wax on head feathers compared with primary and tail feathers. We suggest that among its many functions, preen wax may play a role in drag reduction by affecting the physical properties of feathers, and/or the fluid flow at their surfaces.     

Atomic‐Scale Observation of Oxygen Substitution and Its Correlation with Hole‐Transport Barriers in Cu2ZnSnSe4 Thin‐Film Solar Cells

Kesterite‐type Cu₂ZnSn(S,Se)₄ has been extensively studied over the past several years, with researchers searching for promising candidates for indium‐ and gallium‐free inexpensive absorbers in high‐efficiency thin‐film solar cells. Many notable experimental and theoretical studies have dealt with the effects of intrinsic point defects, Cu/Zn/Sn nonstoichiometry, and cation impurities on cell performance. However, there have been few systematic investigations elucidating the distribution of oxygen at an atomic scale and the correlation between oxygen substitution and charge transport despite unavoidable incorporation of oxygen from the ambient atmosphere during thin‐film fabrication. Using energy‐dispersive X‐ray spectroscopy, scanning transmission electron microscopy, and electron energy‐loss spectroscopy, the presence of nanoscale layers is directly demonstrated in which oxygen is substantially substituted for Se, near grain boundaries in polycrystalline Cu₂ZnSnSe₄ films. Density‐functional theory calculations also show that oxygen substitution remarkably lowers the valence band maximum and subsequently widens the overall bandgap. Consequently, anion modification by oxygen can make a major contribution to the formation of a robust barrier blocking the holes from bulk grains into grain boundaries, thereby efficiently attaining electron?hole separation. The findings provide crucial insights into achieving better energy conversion efficiency in kesterite‐based thin‐film solar cells through optimum control of oxidation during the fabrication process.     

Systematic Evaluation of Protein Sequence Filtering Algorithms for Proteoform Identification Using Top‐Down Mass Spectrometry

Complex proteoforms contain various primary structural alterations resulting from variations in genes, RNA, and proteins. Top‐down mass spectrometry is commonly used for analyzing complex proteoforms because it provides whole sequence information of the proteoforms. Proteoform identification by top‐down mass spectral database search is a challenging computational problem because the types and/or locations of some alterations in target proteoforms are in general unknown. Although spectral alignment and mass graph alignment algorithms have been proposed for identifying proteoforms with unknown alterations, they are extremely slow to align millions of spectra against tens of thousands of protein sequences in high throughput proteome level analyses. Many software tools in this area combine efficient protein sequence filtering algorithms and spectral alignment algorithms to speed up database search. As a result, the performance of these tools heavily relies on the sensitivity and efficiency of their filtering algorithms. Here, we propose two efficient approximate spectrum‐based filtering algorithms for proteoform identification. We evaluated the performances of the proposed algorithms and four existing ones on simulated and real top‐down mass spectrometry data sets. Experiments showed that the proposed algorithms outperformed the existing ones for complex proteoform identification. In addition, combining the proposed filtering algorithms and mass graph alignment algorithms identified many proteoforms missed by ProSightPC in proteome‐level proteoform analyses.