Kinetics and mechanism of large rate enhancement in the alkaline hydrolysis of N'-morpholino-N-(2'-methoxyphenyl)phthalamide

The apparent second-order rate constant (k OH) for hydroxide-ion-catalyzed conversion of 1 to N-(2'-methoxyphenyl)phthalamate (4) is approximately 10(3)-fold larger than k OH for alkaline hydrolysis of N-morpholinobenzamide (2). These results are explained in terms of the reaction scheme 1 --> k(1obs) 3 --> k(2obs) 4 where 3 represents N-(2'-methoxyphenyl)phthalimide and the values of k(2obs)/k(1obs) vary from 6.0 x 10(2) to 17 x 10(2) within [NaOH] range of 5.0 x 10(-3) to 2.0 M. Pseudo-first-order rate constants (k(obs)) for alkaline hydrolysis of 1 decrease from 21.7 x 10(-3) to 15.6 x 10(-3) s(-1) with an increase in ionic strength (by NaCl) from 0.5 to 2.5 M at 0.5 M NaOH and 35 degrees C. The values of k obs, obtained for alkaline hydrolysis of 2 within [NaOH] range 1.0 x 10(-2) to 2.0 M at 35 degrees C, follow the relationship k(obs) = kOH[HO(-)] + kOH'[HO (-)] (2) with least-squares calculated values of kOH and kOH' as (6.38 +/- 0.15) x 10(-5) and (4.59 +/- 0.09) x 10(-5) M (-2) s(-1), respectively. A few kinetic runs for aqueous cleavage of 1, N'-morpholino-N-(2'-methoxyphenyl)-5-nitrophthalamide (5) and N'-morpholino-N-(2'-methoxyphenyl)-4-nitrophthalamide (6) at 35 degrees C and 0.05 M NaOH as well as 0.05 M NaOD reveal the solvent deuterium kinetic isotope effect (= k(obs) (H 2) (O)/ k(obs) (D 2 ) (O)) as 1.6 for 1, 1.9 for 5, and 1.8 for 6. Product characterization study on the cleavage of 5, 6, and N-(2'-methoxyphenyl)-4-nitrophthalimide (7) at 0.5 M NaOD in D2O solvent shows the imide-intermediate mechanism as the exclusive mechanism.     

Photo-Driven Direct C−H Arylation of Quinoxalin-2(1H)-Ones with Aryltriazenes under Catalyst-Free and Ambient Conditions

A photo-induced direct arylation of quinoxalin-2(1H)-ones with aryltriazenes under catalyst-free and ambient conditions was developed. The synthetic importance of this methodology was showcased by the simple operation, good functional group tolerance, and gram-scale synthesis.     

Electrical fingerprinting, 3D profiling and detection of tumor cells with solid-state micropores

Solid-state micropores can provide direct information of ex vivo or in vitro cell populations. Micropores are used to detect and discriminate cancer cells based on the translocation behavior through micropores. The approach provides rapid detection of cell types based on their size and mechano-physical properties like elasticity, viscosity and stiffness. Use of a single micropore device enables detection of tumor cells from whole blood efficiently, at 70% CTC detection efficiency. The CTCs show characteristic electrical signals which easily distinguish these from other cell types. The approach provides a gentle and inexpensive instrument that can be used for specific blood analysis in a lab-on-a-chip setting. The device does not require any preprocessing of the blood sample, particles/beads attachment, surface functionalization or fluorescent tags and provides quantitative and objective detection of cancer cells.     

<em>In Vitro</em> Anti-diabetic Activities and Chemical Analysis of Polypeptide-k and Oil Isolated from Seeds of <em>Momordica charantia</em> (Bitter Gourd)

The amino acid and fatty acid composition of polypeptide k and oil isolated from the seeds of Momordica charantia was analysed. The analysis revealed polypeptide k contained 9 out of 11 essential amino acids, among a total of 18 types of amino acids. Glutamic acid, aspartic acid, arginine and glycine were the most abundant (17.08%, 9.71%, 9.50% and 8.90% of total amino acids, respectively). Fatty acid analysis showed unusually high amounts of C18-0 (stearic acid, 62.31% of total fatty acid). C18-1 (oleic acid) and C18-2 (linoleic acid) were the other major fatty acid detected (12.53% and 10.40%, respectively). The oil was devoid of the short fatty acids (C4-0 to C8-0). Polypeptide k and oil were also subjected to in vitro α-glucosidase and α-amylase inhibition assays. Both polypeptide k and seed oil showed potent inhibition of α-glucosidase enzyme (79.18% and 53.55% inhibition, respectively). α-Amylase was inhibited by 35.58% and 38.02%, respectively. Collectively, the in vitro assay strongly suggests that both polypeptide k and seed oil from Momordica charantia are potent potential hypoglycemic agents.     

A Novel Image Encryption Scheme Based on Elliptic Curves over Finite Rings

Image encryption based on elliptic curves (ECs) is emerging as a new trend in cryptography because it provides high security with a relatively smaller key size when compared with well-known cryptosystems. Recently, it has been shown that the cryptosystems based on ECs over finite rings may provide better security because they require the computational cost for solving the factorization problem and the discrete logarithm problem. Motivated by this fact, we proposed a novel image encryption scheme based on ECs over finite rings. There are three main steps in our scheme, where, in the first step, we mask the plain image using points of an EC over a finite ring. In step two, we create diffusion in the masked image with a mapping from the EC over the finite ring to the EC over the finite field. To create high confusion in the plain text, we generated a substitution box (S-box) based on the ordered EC, which is then used to permute the pixels of the diffused image to obtain a cipher image. With computational experiments, we showed that the proposed cryptosystem has higher security against linear, differential, and statistical attacks than the existing cryptosystems. Furthermore, the average encryption time for color images is lower than other existing schemes.     

Light-Responsive Polyblend Films with Reconfigurable Surface Micropatterns as Rewritable Information Storage Media

Stimulus-sensitive surfaces with tunable morphologies exhibit a wide range of applications in the fields of surface science and engineering. Herein, a cost-effective yet practical strategy is proposed to fabricate photo-sensitive patterning surface on film/substrate wrinkle system based on an azo-containing polyblend. By manipulating the stress field of the bilayer system globally and/or locally upon the stress relaxation triggered by the reversible cis-trans isomerization of the azobenzene, heating/cooling triggered surface wrinkles on the polyblend films could be tailor-made with visible-light-irradiation. Notably, upon selective photo-irradiation, bespoke surface patterns may be cyclically generated or eliminated, allowing these reconfigurable patterned polyblend surfaces to be used as rewritable information storage media for non-ink printing. The as-prepared photo-printed information patterns with high-resolution are shown to be rewritable for multiple cycles and legible for over 90 d in dark ambient conditions. This study not only provides a versatile strategy for flourishing the stimulus-sensitive systems, but also sheds light on the stress relaxation-triggered morphological evolution of the wrinkling polyblend films.