Cobalt(II)‐Catalyzed Electrophilic Alkynylation of 1,3‐Dicarbonyl Compounds To Form Polysubstituted Furans via π–π Activation

Polysubstituted furans were obtained with excellent yields via the electrophilic alkynylation of 1,3‐dicarbonyl compoundsws with phenyl‐ or ester‐substituted brominated alkynes. The reaction is catalyzed by the inexpensive and readily available catalyst, cobalt(II) chloride, and has a wide substrate scope. The C(sp) C(sp³) coupling occurs under mild conditions with short reaction times and does not require an inert atmosphere or ligands. It is proposed that the reaction proceeds through a chelation complex of cobalt(II) with the deprotonated 1,3‐dicarbonyl compound.

     

Smart-Fragile Authentication Scheme for Robust Detecting of Tampering Attacks on English Text

Content authentication, integrity verification, and tampering detection of digital content exchanged via the internet have been used to address a major concern in information and communication technology. In this paper, a text zero-watermarking approach known as Smart-Fragile Approach based on Soft Computing and Digital Watermarking (SFASCDW) is proposed for content authentication and tampering detection of English text. A first-level order of alphanumeric mechanism, based on hidden Markov model, is integrated with digital zero-watermarking techniques to improve the watermark robustness of the proposed approach. The researcher uses the first-level order and alphanumeric mechanism of Markov model as a soft computing technique to analyze English text. Moreover, he extracts the features of the interrelationship among the contexts of the text, utilizes the extracted features as watermark information, and validates it later with the studied English text to detect any tampering. SFASCDW has been implemented using PHP with VS code IDE. The robustness, effectiveness, and applicability of SFASCDW are proved with experiments involving four datasets of various lengths in random locations using the three common attacks, namely insertion, reorder, and deletion. The SFASCDW was found to be effective and could be applicable in detecting any possible tampering.     

Influence of direct electric current on wetting behavior during brazing

Frontiers of Mechanical Engineering - The wetting behavior of liquid metals is of great importance for many processes. For brazing, however, a targeted modification beyond the adjustment of...     

Agricultural Water Use and Trade in Uzbekistan: Situation and Potential Impacts of Market Liberalization

The focus in Uzbekistan on cotton and its irrigation led to large increases in water use with significant downstream impacts, particularly on the Aral Sea. While agriculture is still heavily influenced by the state, Uzbekistan has become more integrated in the global economy since its independence. The major goal of this paper is to examine the interrelationship between agricultural policies and water use during the last 15 years and how moves towards freer markets, such as those which might occur under the World Trade Organization, may impact Uzbekistan's water resources in the future. The results show that partial or full market liberalization may result in an increase in water use. However, the greater message is that non-water policies can have a major impact on water outcomes and therefore should be considered in any discussions of water sector reform.     

Catalytic activation of the phosphatase MKP-3 by ERK2 mitogen-activated protein kinase

MAP kinase phosphatase-3 (MKP-3) dephosphorylates phosphotyrosine and phosphothreonine and inactivates selectively ERK family mitogen-activated protein (MAP) kinases. MKP-3 was activated by direct binding to purified ERK2. Activation was independent of protein kinase activity and required binding of ERK2 to the noncatalytic amino-terminus of MKP-3. Neither the gain-of-function Sevenmaker ERK2 mutant D319N nor c-Jun amino-terminal kinase-stress-activated protein kinase (JNK/SAPK) or p38 MAP kinases bound MKP-3 or caused its catalytic activation. These kinases were also resistant to enzymatic inactivation by MKP-3. Another homologous but nonselective phosphatase, MKP-4, bound and was activated by ERK2, JNK/SAPK, and p38 MAP kinases. Catalytic activation of MAP kinase phosphatases through substrate binding may regulate MAP kinase activation by a large number of receptor systems.     

A new shock damage model: Part I—Model formulation and analysis

In this paper we formulate a new model for system failure due to shock damage and study some aspects of analysis and parameter estimation for the model proposed.     

Copper Chaperone for Cu/Zn Superoxide Dismutase is a sensitive biomarker of mild copper deficiency induced by moderately high intakes of zinc

Background  

Small increases in zinc (Zn) consumption above recommended amounts have been shown to reduce copper (Cu) status in experimental animals and humans. Recently, we have reported that copper chaperone for Cu/Zn superoxide dismutase (CCS) protein level is increased in tissues of overtly Cu-deficient rats and proposed CCS as a novel biomarker of Cu status.     

Enhanced Dielectric Performance in Polymer Composite Films with Carbon Nanotube‐Reduced Graphene Oxide Hybrid Filler

The electrical conductivity and the specific surface area of conductive fillers in conductor‐insulator composite films can drastically improve the dielectric performance of those films through changing their polarization density by interfacial polarization. We have made a polymer composite film with a hybrid conductive filler material made of carbon nanotubes grown onto reduced graphene oxide platelets (rG‐O/CNT). We report the effect of the rG‐O/CNT hybrid filler on the dielectric performance of the composite film. The composite film had a dielectric constant of 32 with a dielectric loss of 0.051 at 0.062 wt% rG‐O/CNT filler and 100 Hz, while the neat polymer film gave a dielectric constant of 15 with a dielectric loss of 0.036. This is attributed to the increased electrical conductivity and specific surface area of the rG‐O/CNT hybrid filler, which results in an increase in interfacial polarization density between the hybrid filler and the polymer.     

The mitogen-activated protein kinase phosphatase-3 N-terminal noncatalytic region is responsible for tight substrate binding and enzymatic specificity

We have reported recently that the dual specificity mitogen-activated protein kinase phosphatase-3 (MKP-3) elicits highly selective inactivation of the extracellular signal-regulated kinase (ERK) class of mitogen-activated protein (MAP) kinases (Muda, M., Theodosiou, A., Rodrigues, N., Boschert, U., Camps, M., Gillieron, C., Davies, K., Ashworth, A., and Arkinstall, S. (1996) J. Biol. Chem. 271, 27205-27208). We now show that MKP-3 enzymatic specificity is paralleled by tight binding to both ERK1 and ERK2 while, in contrast, little or no interaction with either c-Jun N-terminal kinase/stress activated protein kinase (JNK/SAPK) or p38 MAP kinases was detected. Further study revealed that the N-terminal noncatalytic domain of MKP-3 (MKP-3DeltaC) binds both ERK1 and ERK2, while the C-terminal MKP-3 catalytic core (MKP-3DeltaN) fails to precipitate either of these MAP kinases. A chimera consisting of the N-terminal half of MKP-3 with the C-terminal catalytic core of M3-6 also bound tightly to ERK1 but not to JNK3/SAPKbeta. Consistent with a role for N-terminal binding in determining MKP-3 specificity, at least 10-fold higher concentrations of purified MKP-3DeltaN than full-length MKP-3 is required to inhibit ERK2 activity. In contrast, both MKP-3DeltaN and full-length MKP-3 inactivate JNK/SAPK and p38 MAP kinases at similarly high concentrations. Also, a chimera of the M3-6 N terminus with the MKP-3 catalytic core which fails to bind ERK elicits non selective inactivation of ERK1 and JNK3/SAPKbeta. Together, these observations suggest that the physiological specificity of MKP-3 for inactivation of ERK family MAP kinases reflects tight substrate binding by its N-terminal domain.