On the analysis of a kind of nonlinear Sobolev equation through locally applied pseudo‐spectral meshfree radial point interpolation

In this study, we develop an approximate formulation for two‐dimensional nonlinear Sobolev problems by focusing on pseudospectral meshless radial point interpolation (PSMRPI) which is a kind of locally applied radial basis function interpolation and truthfully a meshless approach. In the PSMRPI method, the nodal points do not need to be regularly distributed and can even be quite arbitrary. It is easy to have high order derivatives of unknowns in terms of the values at nodal points by constructing operational matrices. The convergence and stability of the technique in some sense are studied via some examples to show the validity and trustworthiness of the PSMRPI technique.     

Enhancement in sensitivity of nitro blue tetrazolium polyvinyl alcohol film dosimeters by sodium formate and Triton X-100

Nitro blue tetrazolium polyvinyl alcohol film dosimeters, NBT-PVA were prepared and evaluated based on radiation-induced reduction of NBT²⁺. NBT-PVA film dosimeters containing different concentrations of NBT dye from 1 to 5 mM were prepared in a solution of ethanol. The dosimeters were irradiated with ?-ray from ⁶⁰Co source at doses up to 50 kGy. UV/vis spectrophotometer was used to investigate the optical density of un-irradiated and irradiated films in terms of absorbance at 529 nm. The absorbance increases with absorbed dose up to 50 kGy for NBT-PVA film dosimeters. The dose sensitivity of NBT-PVA film increases strongly with increase of concentrations of NBT dye. The effects of irradiation temperature, humidity, dose rate and the stability of the response of the films after irradiation were investigated. A considerable increase was observed in the dose response of NBT-PVA film by adding appropriate concentration of sodium formate and Triton X-100.     

Synthesis and antimicrobial activity of N'-heteroarylidene-1-adamantylcarbohydrazides and (±)-2-(1-adamantyl)-4-acetyl-5-[5-(4-substituted phenyl-3-isoxazolyl)]-1,3,4-oxadiazolines

The reaction of adamantane-1-carbohydrazide (1) with heterocyclic aldehydes, namely 5-(4-chlorophenyl)isoxazole-3-carboxaldehyde (2a), 5-(4-methylphenyl)isoxazole-3-carboxaldehyde (2b), 5-(4-methoxyphenyl)isoxazole-3-carboxaldehyde (2c), 1H-imidazole-2-carboxaldehyde and 2-butyl-4-chloro-1H-imidazole-5-carboxaldehyde, in ethanol, yielded the corresponding N'-heteroarylidene-1-adamantylcarbohydrazides 3a, 3b, 3c, 4 and 5, respectively, in good yields. The 4-acetyl-1,3,4-oxadiazoline analogues 6a?c were prepared in 48-55% yields by heating their corresponding N'-heteroarylidene-1-adamantylcarbohydrazides 3a-c with acetic anhydride for two hours. Compounds 3a-c, 4, 5 and 6a-c were tested for in vitro activities against a panel of Gram-positive and Gram-negative bacteria and the yeast-like pathogenic fungus Candida albicans. Compounds 4 and 5 displayed potent broad-spectrum antimicrobial activity, while compounds 3a-c showed good activity against the Gram-positive bacteria.     

alpha-Mangostin enhances betulinic acid cytotoxicity and inhibits cisplatin cytotoxicity on HCT 116 colorectal carcinoma cells

Despite the progress in colon cancer treatment, relapse is still a major obstacle. Hence, new drugs or drug combinations are required in the battle against colon cancer. α-Mangostin and betulinic acid (BA) are cytotoxic compounds that work by inducing the mitochondrial apoptosis pathway, and cisplatin is one of the most potent broad spectrum anti-tumor agents. This study aims to investigate the enhancement of BA cytotoxicity by α-mangostin, and the cytoprotection effect of α-mangostin and BA on cisplatin-induced cytotoxicity on HCT 116 human colorectal carcinoma cells. Cytotoxicity was investigated by the XTT cell proliferation test, and the apoptotic effects were investigated on early and late markers including caspases-3/7, mitochondrial membrane potential, cytoplasmic shrinkage, and chromatin condensation. The effect of α-mangostin on four signalling pathways was also investigated by the luciferase assay. α-Mangostin and BA were more cytotoxic to the colon cancer cells than to the normal colonic cells, and both compounds showed a cytoprotective effect against cisplatin-induced cytotoxicity. On the other hand, α-mangostin enhanced the cytotoxic and apoptotic effects of BA. Combination therapy hits multiple targets, which may improve the overall response to the treatment, and may reduce the likelihood of developing drug resistance by the tumor cells. Therefore, α-mangostin and BA may provide a novel combination for the treatment of colorectal carcinoma. The cytoprotective effect of the compounds against cisplatin-induced cytotoxicity may find applications as chemopreventive agents against carcinogens, irradiation and oxidative stress, or to neutralize cisplatin side effects.     

Determination of phenoxy herbicides in water samples using phase transfer microextraction with simultaneous derivatization followed by GC‐MS analysis

A sensitive and accurate method for the determination of two model phenoxy herbicides, 4‐chloro‐2‐methylphenoxy acetic acid and 4‐chloro‐2‐methylphenoxy propanoic acid, in water is explained. This method utilizes a simple phase transfer catalyst‐assisted microextraction with simultaneous derivatization. Factors affecting the performance of this method including pH of the aqueous matrix, temperature, extraction duration, type and amount of derivatization reagents, and type and amount of the phase transfer catalyst are examined. Derivatization and the use of phase transfer catalyst have proven to be especially vital for the resolution of the analytes and their sensitive determination, with an enrichment factor of 288‐fold for catalyzed over noncatalyzed procedure. Good linearity ranging from 0.1 to 80 μg L^?1 with correlation of determination (r²) between 0.9890 and 0.9945 were obtained. Previous reported detection limits are compared with our new current method. The low LOD for the two analytes (0.80 ng L^?1 for 4‐chloro‐2‐methylphenoxy propanoic acid and 3.04 ng L^?1 for 4‐chloro‐2‐methylphenoxy acetic acid) allow for the determination of low concentrations of these analytes in real samples. The absence of matrix effect was confirmed through relative recovery calculations. Application of the method to seawater and tap water samples was tested, but only 4‐chloro‐2‐methylphenoxy propanoic acid at concentrations between 0.27 ± 0.01 and 0.84 ± 0.06 μg L^?1 was detected in seawater samples.     

Molecular complexes of aspirin with humic acid extracted from shilajit and their characterization

Aspirin possesses antipyretic, anti-inflammatory, analgesic and anti-aggregatory activity. The acetylsalicylic acid molecule has a carboxyl group and an ester group. The ester group can be easily hydrolyzed, which reduces the medicinal value and causes side effects on humans. The aim of the present study was to prepare solid complexes between aspirin and humic by lyophilization and solvent evaporation technique in the molar ratio 1:1 and 1:2. Molecular interaction between aspirin and humic acid were studied by DSC, XRD, FT-IR and scanning electron microscopy. This technique clearly demonstrated the existence of solid inclusion complex formation. The lyophilized complex in the molar ratio 1:2 showed enhanced stability and dissolution rates of aspirin significantly. A highly significant (p < 0.05) anti-inflammatory action of the treatment of optimized freeze dried (1:2) aspirin complex with humic acid was evidenced by inhibition of rat paw edema and anti-ulcerogenic action was measured by lowest score (0.63 ± 0.10) with significant reduction in ulceration as compared to aspirin alone.     

Fabrication of printed memory device having zinc-oxide active nano-layer and investigation of resistive switching

An all printed resistive memory device, a 9-bit memristor, has been presented in this study consisting of 3 × 3 memristor crossbars deposited via electrohydrodynamic inkjet printing process at room conditions. Transparent zinc oxide active nano-layers, directly deposited by electrospray process, are sandwiched between the crossbars to complete the metal–insulator metal structure consisting of copper–zinc oxide–silver, where Cu and Ag are used as bottom and top electrodes respectively. The 9-bit memristor device has been characterized using current–voltage measurements to investigate the resistive switching phenomenon thereby confirming the memristive pinched hysteresis behavior signifying the read–write and memory characteristics. The memristor device showed a current bistability due to the existence of metal–oxide layer which gives rise to oxygen vacancies upon receiving the positive voltage hence breaking down into doped and un-doped regions and a charge transfer takes place. The maximum ON/OFF ratio of the current bi-stability for the fabricated memristor was as large as 1 × 10³, and the endurance of ON/OFF switchings was verified for 500 read–write cycles. The metal–insulator–metal structure has been characterized using X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope techniques.     

Orange dye polyaniline composite based impedance humidity sensors

This study presents the fabrication and investigation of humidity sensors based on orange dye (OD) and polyaniline (PANI) composite films. A blend of 3 wt.% OD with 1 wt.% PANI was prepared in 1 ml water. The composite films were deposited on glass substrates between pre-deposited silver electrodes. The gap between the electrodes was 45 μm. The sensing mechanism was based on the impedance and capacitance variations due to the absorption/desorption of water vapor. It was observed that with the increase in relative humidity (RH) from 30% to 90%, the impedance decreases by 5.2 × 10 4 and 8.8 × 10 3 times for the frequencies of 120 Hz and 1 kHz, respectively. The impedance-humidity relationship showed a more uniform change compared to the capacitance-humidity relationship in the RH range of 30% to 90%. The consequence of annealing, measuring frequency, response and recovery time, and absorption-desorption behavior of the humidity sensor were also discussed in detail. The annealing resulted in an increase in sensitivity of up to 2.5 times, while the measured response time and recovery time were 34 s and 450 s, respectively. The impedance-humidity relationship was simulated.     

The Duality Property of Positive R-Compact Operators

We study the duality of r-compact operator. We establish if an operator ${T:E\rightarrow F}$ is r-compact, then its adjoint ${T^{\prime}: F^{\prime }\rightarrow E^{\prime }}$ is also r-compact. We also provide some sufficient condition on the pair of Banach lattices E and F which guarantees that a regular operator ${T:E\rightarrow F}$ such that ${T^{\prime }:F^{\prime }\rightarrow E^{\prime }}$ is r-compact, must itself be r-compact.     

A new fatty ester and a new triterpene from Skimmia laureola

Aerial parts of Skimmia laureola yielded a new fatty ester, (+)-skimmilaureol (1), and a new triterpene 16-29-dihydroxy, 20-ene cyclolaudenol (2). Five known compounds, namely, O-methyl-cyclolaudenol (3), (R)-7-methoxy-6-(3'-hydroxy-2'R-methoxy-3'-methyl butyl)coumarin (4), (+)-(S)-psi-ribalinine (5), (R)-(+)-ribalinine (6) and methyl isoplatydesmine (7), previously isolated from this plant were subjected to enzymatic bioassays for the first time. Compounds 3 and 4 were found to be prolyl endopeptidase inhibitors with IC(50) 8.21 +/- 0.407 and 39.63 +/- 1.502 microM, respectively, while compounds 5-7 were found to be acetyl-cholinesterase and butyryl-cholinesterase inhibitors with IC(50) 62.46 +/- 1.58, 153.31 +/- 1.9, 74.5 +/- 1.05 and 150.04 +/- 0.45, 12.99 +/- 0.31, 78.3 +/- 1.86 microM, respectively.