A Critical Review on Pulsed Electric Field: A Novel Technology for the Extraction of Phytoconstituents

Different parts of a plant (seeds, fruits, flower, leaves, stem, and roots) contain numerous biologically active compounds called “phytoconstituents” that consist of phenolics, minerals, amino acids, and vitamins. The conventional techniques applied to extract these phytoconstituents have several drawbacks including poor performance, low yields, more solvent use, long processing time, and thermally degrading by-products. In contrast, modern and advanced extraction nonthermal technologies such as pulsed electric field (PEF) assist in easier and efficient identification, characterization, and analysis of bioactive ingredients. Other advantages of PEF include cost-efficacy, less time, and solvent consumption with improved yields. This review covers the applications of PEF to obtain bioactive components, essential oils, proteins, pectin, and other important materials from various parts of the plant. Numerous studies compiled in the current evaluation concluded PEF as the best solution to extract phytoconstituents used in the food and pharmaceutical industries. PEF-assisted extraction leads to a higher yield, utilizes less solvents and energy, and it saves a lot of time compared to traditional extraction methods. PEF extraction design should be safe and efficient enough to prevent the degradation of phytoconstituents and oils.     

Application of Euler Neural Networks with Soft Computing Paradigm to Solve Nonlinear Problems Arising in Heat Transfer

In this study, a novel application of neurocomputing technique is presented for solving nonlinear heat transfer and natural convection porous fin problems arising in almost all areas of engineering and technology, especially in mechanical engineering. The mathematical models of the problems are exploited by the intelligent strength of Euler polynomials based Euler neural networks (ENN’s), optimized with a generalized normal distribution optimization (GNDO) algorithm and Interior point algorithm (IPA). In this scheme, ENN’s based differential equation models are constructed in an unsupervised manner, in which the neurons are trained by GNDO as an effective global search technique and IPA, which enhances the local search convergence. Moreover, a temperature distribution of heat transfer and natural convection porous fin are investigated by using an ENN-GNDO-IPA algorithm under the influence of variations in specific heat, thermal conductivity, internal heat generation, and heat transfer rate, respectively. A large number of executions are performed on the proposed technique for different cases to determine the reliability and effectiveness through various performance indicators including Nash–Sutcliffe efficiency (NSE), error in Nash–Sutcliffe efficiency (ENSE), mean absolute error (MAE), and Thiel’s inequality coefficient (TIC). Extensive graphical and statistical analysis shows the dominance of the proposed algorithm with state-of-the-art algorithms and numerical solver RK-4.     

Synthesis and resolution of diethyl (1S,2S)-1-amino-2-vinylcyclopropane-1-phosphonate for HCV NS3 protease inhibitors

We herein describe an efficient synthesis of optically active diethyl 1-amino-2-vinylcyclopropane-1-phosphonate (analogous to 1-amino-2-vinylcyclopropane-1-carboxylate). The racemic phosphonate diethyl ester was obtained from an imine derived from aminomethylphosphonate diester and trans-1,4-dibromo-2-butene. Crystallizations of the dibenzoyl-l-tartaric acid salt allowed for separation of enantiomers. The enantiomerically pure material was used to synthesize an extremely potent tripeptide phosphonate inhibitor of HCV NS3 protease. X-ray crystal structure of the inhibitor bound to the HCV NS3 protease confirmed the absolute stereochemistry of the title compound.     

Lyciumaside and Lyciumate: A New Diacylglycoside and Sesquiterpene Lactone from Lycium shawii

One new diacylglycoside named lyciumaside ( 1 ) and a new sesquiterpene lactone named lyciumate ( 2 ) were isolated from Lycium shawii Roem . & Schult . The structures of the two new compounds were elucidated based on 1D‐ (¹H‐ and ¹³C‐NMR and NOE) and 2D‐NMR (COSY, HSQC, and HMBC) spectroscopic techniques, and mass spectrometry (ESI‐MS). Preliminary evaluations demonstrated lyciumaside ( 1 ) possesses strong antioxidant activity with an IC₅₀ = 30 μg/ml (80% inhibition) while it was inactive in α‐glucosidase and urease enzymes assays.     

Identification and structural characterization of major degradation products of tapentadol by using liquid chromatography–tandem mass spectrometry

Tapentadol, a centrally acting analgesic was subjected to hydrolysis (acidic, alkaline, and neutral), oxidation, photolysis, humidity, and thermal stress conditions as per International Conference on Harmonization prescribed guidelines. Tapentadol was found susceptible to oxidative stress that produced two major degradation products DP-I and DP-II. However, it was stable to hydrolysis, photolysis, and thermal stress conditions. A simple, sensitive, and accurate high-performance liquid chromatography stability-indicating assay method (liquid chromatography–mass spectrometer compatible) was developed and validated for identification and characterization of stressed degradation products of Tapentadol. The chromatographic separation of the drug and its degradation products were achieved on Inertsil ODS, C18 (250 × 4.6 mm, i.d., 5 µm) column using a 12.5 mM aqueous ammonium acetate buffer (with 0.2% triethyl amine and final pH of buffer was adjusted to 3.60 with glacial acetic acid): acetonitrile (75:25, v/v) as a mobile phase. The degradation products were characterized by liquid chromatography mass spectrometry and subsequently its fragmentation pathway as well as plausible mechanism for generation of degradation products was also proposed. The stability indicating high-performance liquid chromatographic method was validated with respect to linearity, precision, and accuracy.     

Effect of Indium and Antimony Doping on SnS Photoelectrochemical Solar Cells

Single crystals of pure SnS, indium （In） and antimony （Sb） doped SnS are grown by the direct vapor transport technique. Two doping concentrations of 5 at. % and 15 at. % are employed for both In and Sb dopants. In total, five samples are studied, i.e., pure SnS, 5at.% In-doped SnS, 15at.% In-doped SnS, 5at.% Sb-doped SnS and 15at.% Sb-doped SnS single crystals. The energy dispersive analysis of x-ray （EDAX） and x-ray diffraction （XRD） analysis show that all the five as-grown single crystal samples possess near perfect stoichiometry and orthorhombic structure, respectively. The doping of In and Sb in SnS is established from the EDAX data and from the shift in the peak positions in XRD. Photoeleetroehemical （PEC） solar cells are fabricated by using the as- grown single crystal samples along with iodine/iodide electrolytes. Mott-Schottky plots for different compositions of iodine/iodide electrolytes show that O. 025 M 12 ＋ 1 M Nal＋2 M Na2 S04 ＋0.5 M 1-12 S04 will be the most suitable electrolyte. Study of efficiency （η） and fill factor for different intensities of illuminations at room temperature is carried out for the five samples. The In-doped SnS single crystals show better PEC efficiency than the undoped and Sl〉doped SnS single crystals.     

Molecular precursors for the preparation of homogenous zirconia-silica materials by hydrolytic sol-gel process in organic media. Crystal structures of [Zr{OSi(O(t)Bu)3}4(H2O)2]·2H2O and [Ti(O(t)Bu){OSi(O(t)Bu)3}3

[Zr(OPr(i))(4)·Pr(i)OH] reacts with [HOSi(O(t)Bu)(3)] in anhydrous benzene in 1:1 and 1:2 molar ratios to afford alkoxy zirconosiloxane precursors of the types [Zr(OPr(i))(3){OSi(O(t)Bu)(3)}] (A) and [Zr(OPr(i))(2){OSi(O(t)Bu)(3)}(2)] (B), respectively. Further reactions of A or B with glycols in 1:1 molar ratio afforded six chemically modified precursors of the types [Zr(OPr(i))(OGO){OSi(O(t)Bu)(3)}] (1A-3A) and [Zr(OGO){OSi(O(t)Bu)(3)}(2)] (1B-3B), respectively [where G = (-CH(2)-)(2) (1A, 1B); (-CH(2)-)(3) (2A, 2B) and (-CH(2)CH(2)CH(CH(3)-)} (3A, 3B)]. The precursors A and B are viscous liquids, which solidify on ageing whereas the other products are all solids, soluble in common organic solvents. These were characterized by elemental analyses, molecular weight measurements, FAB mass, FTIR, (1)H, (13)C and (29)Si-NMR studies. Cryoscopic molecular weight measurements of all the products, as well as the FAB mass studies of 3A and 3B, indicate their monomeric nature. However, FAB mass spectrum of the solidified B suggests that it exists in dimeric form. Single crystal structure analysis of [Zr{OSi(O(t)Bu)(3)}(4)(H(2)O)(2)]·2H(2)O (3b) (R(fac) = 11.9%) as well as that of corresponding better quality crystals of [Ti(O(t)Bu){OSi(O(t)Bu)(3)}(3)] (4) (R(fac) = 5.97%) indicate the presence of a M-O-Si bond. TG analyses of 3A, B, and 3B indicate the formation of zirconia-silica materials of the type ZrO(2)·SiO(2) from 3A and ZrO(2)·2SiO(2) from B or 3B at low decomposition temperatures (≤200 °C). The desired homogenous nano-sized zirconia-silica materials [ZrO(2)·nSiO(2)] have been obtained easily from the precursors A and B as well as from the glycol modified precursors 3A and 3B by hydrolytic sol-gel process in organic media without using any acid or base catalyst, and these were characterized by powder XRD patterns, SEM images, EDX analyses and IR spectroscopy.     

Time-resolved time-dependent photo-acoustic spectroscopy of NO2 in a high frequency multi-resonant cavity

The paper reports the pulsed laser-based time-resolved time-dependent Photo-acoustic (PA) spectroscopy of NO₂ gas in a specially designed multi mode-Resonant PA Cell which is made of Stainless Steel and has a “Q” value of the order of 79. Furthermore the designed cell allows us to excite some of the longitudinal, radial and azimuthal resonance modes of the photo-acoustic signals simultaneously in a very efficient manner. The presence of many newly excited modes occur at 7050 Hz, 10350 Hz and 14650 Hz frequencies is observed for the first time in NO₂ at room temperature. These results are obtained by employing second harmonics i.e. λ=532 nm pulses from Q-switched Nd:YAG laser having 7 ns pulse duration. Some of the new acoustic spectrum lines at higher frequencies are recorded between 0.5–10 ms data acquisition time, which also extends the frequency monitoring range of our system. The study also highlights some of the important aspects such as the decaying behavior of some of these resonant acoustic spectrum lines occur on the expense of others as well as the saturation behavior of some other modes in the NO₂ gas sample. The estimated low level detection limit of NO₂ buffered in air is of the order of 17.9 ppbV.