Gas-phase chiral separations by ion mobility spectrometry

This article introduces the concept of chiral ion mobility spectrometry (CIMS) and presents examples demonstrating the gas-phase separation of enantiomers of a wide range of racemates including pharmaceuticals, amino acids, and carbohydrates. CIMS is similar to traditional ion mobility spectrometry, where gas-phase ions, when subjected to a potential gradient, are separated at atmospheric pressure due to differences in their shapes and sizes. In addition to size and shape, CIMS separates ions based on their stereospecific interaction with a chiral gas. In order to achieve chiral discrimination by CIMS, an asymmetric environment was provided by doping the drift gas with a volatile chiral reagent. In this study (S)-(+)-2-butanol was used as a chiral modifier to demonstrate enantiomeric separations of atenolol, serine, methionine, threonine, methyl alpha-glucopyranoside, glucose, penicillamine, valinol, phenylalanine, and tryptophan from their respective racemic mixtures.     

Surface conduction behaviour of 100 Mev Si ion irradiated kapton-H polyimide

The surface conduction behaviour of kapton-H polyimide irradiated with 100 MeV Si⁺ ion (Fluences 2.3 × 10¹¹, 2.3 × 10¹² and 1.3 × 10¹³ ions/cm²) has been investigated in the temperature range 21 to 150°C. The current-voltage (I-V) characteristics in the low field region i.e., below 10 kV/cm show ohmic behaviour whereas non-linearity occurs in the high field region. The non-linear region is temperature dependent. The nature of I-V characteristics of pristine kapton-H samples doesnt differ much from the irradiated samples suggesting that the surface charge conduction mechanisms are not much affected due to irradiation. The ionic jump distance estimations (3–18 Å) supports to ionic conduction process below 110°C. The Poole-Frenkel and Schottky coefficient estimations show that Poole-Frenkel and Schottky conduction mechanisms are operative at moderate and low temperatures, respectively. The observed change in surface resistivity () in the irradiated samples has been associated to the increase in delocalized -electrons and cross-linking.     

Primary metabolites and organic acid metabolism in apple (Malus sylvestris) fruit callus culture

In-vitro culture cells were obtained from seven different varieties of Indian apples (Malus sylvestris L). The cultivar Golden Delicious showed the highest yield of callus tissue followed by Maharaji and American Epirouge. Cultured apple cells exhibited some deviation from the apple fruit in primary metabolism as well as primary metabolite profiles. In callus cultures, the pool size of free amino acids and organic acids increased considerably while the free sugar pool decreased drastically compared with apple fiuit. There was higher incorporation of ¹⁴C acetate, ¹⁴C citrate, ¹⁴C malate and ¹⁴C succinate into the CO₂, lipid, protein, carbohydrate and amino acid fractions and lower incorporation into the free sugar fraction in cultured cells compared with the explant. The incorporation of ¹⁴CO₂ showed a similar trend. Qualitatively, there was some similarity between the callus and explant in free amino acid and sugar profiles and dissimilarity in organic acids. Compounds such as citrate, succinate and fumarate and also some amino acids (methionine, arginine, leucine and proline) were present at higher concentration in callus cultures whereas they were almost absent in the original tissue. There were also differences in the carbohydrate and protein profiles of explant ana callus as judged by their sugar and amino acid make-up respectively.     

Biochemical studies with garlic (Allium sativum) cell cultures showing different flavour levels

Garlic (Allium sativum L) cell cultures, unorganised white as well as organised green callus, revealed a total of five amino acid precursors (methyl, propyl, allyl, cysteine sulphoxides) and two unidentified ninhydrin-positive compounds. All the five compounds were hydrolysable by alliin lyase to yield pyruvic acid. Their relative concentration varied in the cultured systems and the explant. The total flavour substrate index in globular white callus and semi-differentiated green callus was 4 and 13% respectively of the original explant. In contrast to the substrate levels, the specific activity of alliin lyase enzyme showed half the original activity of the garlic bulb explant. The relationship between intermediary metabolism and flavour formation was studied in these cultures with the help of ¹⁴C-glucose and ¹⁴C-methionine. The incorporation of ¹⁴C label was lower in the protein, carbohydrate and lipid fractions with a concomitant higher incorporation in the volatile fraction of semi-differentiated cultures, whereas this trend was reversed in the white globular callus. ¹⁴C Conversion to the flavour fraction was much lower in the in-vitro cultures when compared with the garlic bulb. The activity of some enzymes such as amino transferase, malate dehydrogenase, polyphenol oxidase, peroxidase, and alkaline phosphatase was higher in the cultured cells than in garlic bulb. There were differences also in the protein, free amino acid profiles and peroxidase isozymes of garlic cell cultures and the original explant.     

Energy Efficient Energy Hole Repelling (EEEHR) Algorithm for Delay Tolerant Wireless Sensor Network

Reducing energy consumption and increasing network lifetime are the major concerns in Wireless Sensor Network (WSN). Increase in network lifetime reduces the frequency of recharging and replacing batteries of the sensor node. The key factors influencing energy consumption are distance and number of bits transmitted inside the network. The problem of energy hole and hotspot inside the network make neighbouring nodes unusable even if the node is efficient for data transmission. Energy Efficient Energy Hole Repelling (EEEHR) routing algorithm is developed to solve the problem. Smaller clusters are formed near the sink and clusters of larger size are made with nodes far from the sink. This methodology promotes equal sharing of load repelling energy hole and hotspot issues. The opportunity of being a Cluster Head (CH) is given to a node with high residual energy, very low intra cluster distance in case of nodes far away from the sink and very low CH to sink distance for the nodes one hop from the sink. The proposed algorithm is compared with LEACH, LEACH-C and SEP routing protocol to prove its novel working. The proposed EEEHR routing algorithm provides improved lifetime, throughput and less packet drop. The proposed algorithm also reduces energy hole and hotspot problem in the network.     

Development and characterization of a ricinoleic acid poloxamer gel system for transdermal eyelid delivery

Objective: This study deals with the preparation and evaluation of a pluronic lecithin organogel (PLO gel) containing ricinoleic acid for the transdermal eyelid delivery of dexamethasone and tobramycin.

Methods: Five different PLO gel formulations (F1, F2, F3, F4 and F5) containing tobramycin (0.3%) and dexamethasone (0.1%) were prepared and compared to a conventional PLO gel (light mineral oil PLO gel, F6) with respect to physical appearance and viscosity. The optimized ricinoleic acid PLO gel formulation (F2) was further characterized for pH, gelation temperature, morphology and drug content. Ex vivo permeability of dexamethasone and bactericidal activity of tobramycin from formulation F2 was tested, and values were compared to the marketed Tobradex® eye ointment.

Results: No apparent changes in the physical appearance and consistency were observed when ricinoleic acid was used as the oil phase. The pH of the optimized ricinoleic acid PLO gel (formulation F2) was found to be 6.54 with a gelation temperature of 31?°C. The drug content of tobramycin and dexamethasone were found to be 102.8% and 100.14%, respectively. The penetration profile of dexamethasone from formulation F2 was found to be much higher than the marketed Tobradex® eye ointment. F2 showed a better antimicrobial activity and higher zones of inhibition when compared to the marketed Tobradex® eye ointment.

Conclusion: The findings of this investigation indicate that the ricinoleic acid PLO gel has the potential for use as a transdermal eyelid delivery system.     

Influence of double application technique on the bonding effectiveness of self‐etch adhesive systems

Aim: To evaluate and compare the effect of double‐application of single‐step self‐etch adhesives using microleakage study and to analyze the dentin–adhesive interfacial micromorphology. Methods: In total, 72 extracted human premolars were divided into three groups for different self‐etch adhesives (G Bond, GC [GB], Optibond, Kerr [OB], and Xeno V Plus, Dentsply [XV]). Class V cavities were prepared. Each group was further divided into two subgroups (n = 10) according to the placement technique of the adhesive, using the single‐application [subgroup (a)] or double‐application method [subgroup (b)]. Resin composite (Z 250, 3M ESPE, St. Paul, MN) was used to restore the cavities and light cured for 40 s. Twenty samples from each group were subjected to microleakage study. Two samples from both the subgroups of the three adhesives were used for scanning electron microscopic examination of the resin–dentin interfacial ultrastructure. Dye leakage scores were subjected to statistical analysis using Kruskal–Wallis and Mann–Whitney U‐tests at significance level of P < 0.05. Results: GB depicted significantly more microleakage which was significantly greater than OB and XV. The double application led to significant decrease in microleakage of GB with no significant effect on the microleakage scores of other two all‐in‐one adhesives, that is OB and XV. Conclusion: Double application of all‐in‐one self‐etch adhesives improves the marginal sealing ability in dentin although it appears to be product dependent. Microsc. Res. Tech. 78:489–494, 2015. © 2015 Wiley Periodicals, Inc.     

Multiple forms of β‐galactosidase from mango (Mangifera indica L Alphonso) fruit pulp

Mango (Mangifera indica L cv Alphonso) was found to contain three isoforms (I, II and III) of β‐galactosidase which, upon purification on Sephadex G‐200, had relative abundances of 44, 38 and 18%, respectively. The total specific activity increased from 20 to 727 µmol l^?1 upon purification, representing a ～36‐fold increase with a recovery of 0.28 U U^?1. The optimal pH for activity and stability were in the ranges 3.6–4.3 and 4–6.2, respectively. The optimal temperature for β‐galactosidase activity was between 42 and 47 °C with T_m in the range 45–51 °C. The K_m for pNP‐β‐galactopyranoside was 0.98, 1.11 and 0.95 mM , and V_max was 0.56, 0.53 and 0.35 µmol pNP min^?1, respectively for isoforms I, II and III. Hg²⁺ caused strong inhibition, whereas galacturonic acid, galactose, xylose, fucose and mannose slightly inhibited the activity of β‐galactosidase isoforms. The apparent molecular weights by GPC were 78, 58 and 91 kDa for isoforms I, II and III, respectively. The ability of these isoforms to degrade the endogenous substrate (arabinogalactan) possibly suggests a role in pectin dissolution during tissue softening/fruit ripening. Copyright © 2004 Society of Chemical Industry     

Apoptotic Effects of Chrysin in Human Cancer Cell Lines

Chrysin is a natural flavonoid currently under investigation due to its important biological anti-cancer properties. In most of the cancer cells tested, chrysin has shown to inhibit proliferation and induce apoptosis, and is more potent than other tested flavonoids in leukemia cells, where chrysin is likely to act via activation of caspases and inactivation of Akt signaling in the cells. Moreover, structure-activity relationships have revealed that the chemical structure of chrysin meets the key structural requirements of flavonoids for potent cytotoxicity in leukemia cells. It is possible that combination therapy or modified chrysin could be more potent than single-agent use or administration of unmodified chrysin. This study may help to develop ways of improving the effectiveness of chrysin in the treatment of leukemia and other human cancers in vitro.     

CFD analysis of a flat tube with semi-circular fins using graphene nanofluid and to compare performance with square type of fins

CFD analysis on a flat tube with semi-circular fins under laminar flow conditions was performed with graphene-based nanofluids considering the nanofluids as incompressible. Different simulations were performed at four different concentrations of nanofluids (0.01%, 0.1%, 0.2%, and 0.4%) and at different volume flow rates (4, 6, 8, and 10 LPM) and at four different forced convective heat transfer coefficients at different wind velocities at 300 K (50, 100, 150, and 200 W/m² K). It was observed that with an increase in the concentration of nanoparticles in nanofluids, the thermal conductivity of base fluid water was increased (at 353 K the nanofluid of 0.4% volume concentration, the thermal conductivity of nanofluid increased by 200% with respect to base fluid). Graphene-based nanofluids have higher effectiveness than most nanofluids hence it is considered for the analysis, at 0.4% concentration of nanofluid the effectiveness observed was 36.84% at 4 LPM, and for water, the effectiveness was 28.22% under similar conditions. The effect of flow rate on temperature drop was significant. At 4 LPM and at 0.4% of nanofluid, an outlet coolant temperature of 333 K was observed whereas the water outlet temperature at 10 LPM is 346.13 K. The effect of forced convective air heat transfer coefficient was significantly high. At h = 50 W/m² K the outlet temperature of 0.4% nanofluid at 4 LPM was 345.25 K and at h = 200 W/m² K, the outlet coolant temperature was 333.47 K. A single tube of the radiator was considered for the analysis whereas the original radiator consists of 50 tubes due to problems of Ansys in meshing.