Unconventional mechanism and selectivity of the Pd-catalyzed C–H bond lactonization in aromatic carboxylic acid

The search for more effective and highly selective C–H bond oxidation of accessible hydrocarbons and biomolecules is a greatly attractive research mission. The elucidating of mechanism and controlling factors will, undoubtedly, help to broaden scope of these synthetic protocols, and enable discovery of more efficient, environmentally benign, and highly practical new C–H oxidation reactions. Here, we reveal the stepwise intramolecular SN2 nucleophilic substitution mechanism with the rate-limiting C–O bond formation step for the Pd(II)-catalyzed C(sp3)–H lactonization in aromatic 2,6-dimethylbenzoic acid. We show that for this reaction, the direct C–O reductive elimination from both Pd(II) and Pd(IV) (oxidized by O2 oxidant) intermediates is unfavorable. Critical factors controlling the outcome of this reaction are the presence of the η3-(π-benzylic)–Pd and K+–O(carboxylic) interactions. The controlling factors of the benzylic vs ortho site-selectivity of this reaction are the: (a) difference in the strains of the generated lactone rings; (b) difference in the strengths of the η3-(π-benzylic)–Pd and η2-(π-phenyl)–Pd interactions, and (c) more pronounced electrostatic interaction between the nucleophilic oxygen and K+ cation in the ortho-C–H activation transition state. The presented data indicate the utmost importance of base, substrate, and ligand in the selective C(sp3)–H bond lactonization in the presence of C(sp2)–H.

Texture and Geochemistry of Scheelites in the Tongshankou Deposit in Daye, Hubei, China: Implication for REE Substitution Mechanism and Multistage W Mineralization Processes

The Tongshankou skarn deposit in the Edong ore district is a typical metasomatic deposit associated with adjacent granodiorite porphyry and carbonate rocks. Using comprehensive microscopic observations, mineralogical and geochemical analysis, scheelite grains in the skarns can be classified into three major types, showing multi-stage mineralization characteristics. In the redox fluid environment, scheelites that occur with garnets usually have affinity to garnets, while in later skarn phases others exist with oxides and sulfides. They can be subdivided by trace elements, such as Nb and Eu, to discuss the detailed ore-forming process. Scheelites have three typical substitution mechanisms including: 2Ca2 + ⇌ REE3 + +Na+ (1); Ca2 + + W6 + ⇌ REE3 + +Nb5+(2); and 3Ca2 + ⇌ 2REE3++ □Ca (□Ca = Ca site vacancy) (3). Plagioclase or various hydrothermal stages can cause Eu anomalies to fluctuate from positive to negative, and these processes can cause particular zonation in W and Mo contents in scheelites. This study highlights the use of texture and geochemistry of scheelites in skarn deposits, depicting the W mineralization processes.

The Effects of Legal Origin and Corporate Governance on Financial Firms’ Sustainability Performance

This paper examines the determinants of sustainability performance in the financial industry at the firm, country and legal origin levels. Through the analysis of the ESG score in a sample of 64 countries with 982 financial firms during the period between 2002 and 2018, we find that legal origin is a significant explanatory variable. In particular, our findings indicate that companies based in civil-law countries show higher values of ESG performance than their counterparts in common-law countries, suggesting the prevalence of the stakeholder theory in explaining the willingness of financial firms to engage in sustainability practices. Moreover, and following the assumptions of the “good governance” view, we also assess the joint the effect of corporate governance and legal origin ESG scores, finding that corporate governance structures emerge as a substitution mechanism of sustainability enhancement for financial firms based in common-law countries.

CLIFD: A novel image forgery detection technique using digital signatures

The paper presents a new image forgery detection technique. The proposed technique uses digital signatures; it generates a digital signature for each column and embeds the signature in the least significant bits of each corresponding column’s selected pixels. The message digest algorithm 5 (MD5) is used for digital signature generation, and the fourleast-significant-bit substitution mechanism is used to embed the signature in the designated pixels. The embedding of the digital signature in the selected pixel remains completely innocent and undetectable for the human visual system. The proposed forgery detection technique has demonstrated significant results against different types of forgeries introduced to digital images and successfully detected and pointed out the forged columns.

Opportunities and Threats for Innovative Import Substitution in Russia

The article examines the development of import substitution in Russia from the historical perspective, confirming the need for an innovative strategy instead of the model of catch-up development. The study investigates international and domestic approaches to the implementation and impact of innovations, noting achievements and considerable potential of Russian science. Analysis of certain economic indicators for the period 2017-2019 revealed positive trends in the development of agricultural industry, negative dynamics of industrial production, a decline in manufacturing production and growth in mining. A decrease in research and development expenditures and a decline in the number of design, design and survey organizations, and researchers led to a decrease in production share of high-tech and knowledge-intensive industries in gross domestic product. There is a slight increase in exports, including its share in world exports. The problems and achievements of import substitution are considered on the example of the agricultural and aviation industries. The SWOT analysis identified the strengths, weaknesses, opportunities, and threats for the development of Russian import substitution, considering the innovative component. Finally, the paper proposes an author’s approach to a cross-sectoral assessment of import substitute products in order to create an effective import substitution mechanism, considering the innovative component.

Non-porous interpenetrating Co-bpe MOF for colorimetric iodide sensing

An interpenetrating non-porous ladder shaped MOF, Co-bpe, display remarkable solvatochromic iodide sensing through a double nucleophilic substitution mechanism.