Kink-Soliton, Singular-Kink-Soliton and Singular-Periodic Solutions for a New Two-Mode Version of the Burger-Huxley Model: Applications in Nerve Fibers and Liquid Crystals

New two-mode version of Burger-Huxley equation is derived using Korsunsky's operators. The new model arises in the applications of nerve fibers and liquid crystals and describes the interaction of two symmetric waves moving simultaneously in the same direction. Kink-soliton, singular-kink-soliton and singular-periodic solutions are obtained to this model by means of the simplified bilinear method, polynomial-function method and the Kudryashov-expansion method. A comprehensive graphical analysis is conducted to show the physical aspects of this new type of nonlinear equations. Finally, all obtained solution are verified by direct substitution in the model.

Late-stage Derivatization of Buflavine by Nickel-catalyzed Direct Substitution of a Methoxy Group via C-O Bond Activation

The nickel-catalyzed cross-coupling of methoxyarenes is applied to buflavine, which allows for the selective mono-substitution of one of the two methoxy groups in the molecule, leading to the formation of 2- and 3-substituted isomers. Trimethylsilylmethyl (TMSCH2), phenyl and alkynyl groups can be introduced to buflavine using this method. The resulting TMSCH2 analog of buflavine can also be converted into several other derivatives.

Zirconium-catalysed direct substitution of alcohols: enhancing the selectivity by kinetic analysis

Kinetic analysis was used as a tool for rational optimization of catalytic direct substitution of alcohols to enable selective formation of ethers, thioethers, and Friedel–Crafts alkylation products using a moisture-tolerant and commercially available Zr complex.

Extracellular Production, Characterization, and Engineering of a Polyextremotolerant Subtilisin-Like Protease From Feather-Degrading Thermoactinomyces vulgaris Strain CDF

Here, the gene encoding a subtilisin-like protease (protease Als) was cloned from Thermoactinomyces vulgaris strain CDF and expressed in Escherichia coli. The recombinant enzyme was released into the culture medium of E. coli as a mature form (mAls). Purified mAls displayed optimal activity at 60–70°C and pH 10.0 using azo-casein as the substrate, and showed a half-life of 13.8 h at 70°C. Moreover, the activity of thermostable mAls was comparable to or higher than those of mesophilic subtilisin Carlsberg and proteinase K at low temperatures (10–30°C). Protease Als was also stable in several organic solvents and showed high compatibility with commercial laundry detergents. Notably, mAls exhibited approximately 100% of its activity at 3 M NaCl, and showed enhanced thermostability with the increase of NaCl concentration up to 3 M. Protease Als possesses an excess of solvent-accessible acidic amino acid residues, which may account for the high halotolerance of the enzyme. Compared with homologous protease C2 from the same strain, protease Als exhibits substantially lower activity toward insoluble keratin substrates but efficiently hydrolyzes soluble keratin released from chicken feathers. Additionally, direct substitution of the substrate-binding site of protease Als with that of protease C2 improves its activity against insoluble keratin substrates. By virtue of its polyextremotolerant attribute and kerationolytic capacity, protease Als may find broad applications in various industries such as laundry detergents, food processing, non-aqueous biocatalysis, and feather processing.

A Review of β-Lactam–Associated Neutropenia and Implications for Cross-reactivity

Objective: To review the incidence, management, and current understanding of the pathophysiology of β-lactam–induced neutropenia and to critically evaluate the practicality and safety of direct substitution to an alternative β-lactam in the setting of this reaction. Data Sources: A literature analysis using the PubMed and Ovid search engines (July 1968 to October 2020) was performed using the search terms neutropenia, leukopenia, β-lactam, nonchemotherapy, agranulocytosis, and G-CSF (granulocyte colony-stimulating factor). Study Selection and Data Extraction: The included English-language studies evaluated the incidence, mechanism, and/or management of β-lactam–induced neutropenia in pediatric or adult patients. Data Synthesis: Drug-induced neutropenia is a well-documented adverse reaction of β-lactam antibiotics, with an incidence of approximately 10% following at least 2 weeks of intravenous therapy. However, multiple gaps in knowledge remain in the mechanism of pathophysiology and optimal management of this reaction. Both direct toxic and immune-mediated mechanisms have been implicated. Although the cornerstone of management includes cessation of the offending agent, controversy exists on the appropriateness of direct substitution or future use of an alternative β-lactam. Relevance to Patient Care and Clinical Practice: Given the frequency of use and superiority of β-lactams over alternative therapy for several infectious disease states, practical recommendations are needed on the management and safe use of β-lactams following β-lactam–induced neutropenia. Conclusion: Future use of β-lactams with differing R1 side chains, particularly those from a separate class, should not be deemed contraindicated following β-lactam–induced neutropenia and may be considered when indicated, with close laboratory monitoring.

Comparison of Substituting Ability of Nitronate versus Enolate for Direct Substitution of a Nitro Group

α-Nitrocinnamate underwent the conjugate addition of an active methylene compound such as nitroacetate, 1,3-dicarbonyl compound, or α-nitroketone, and the following ring closure afforded functionalized heterocyclic frameworks. The reaction of cinnamate with nitroacetate occurs via nucleophilic substitution of a nitro group by the O-attack of the nitronate, which results in isoxazoline N-oxide. This protocol was applicable to 1,3-dicarbonyl compounds to afford dihydrofuran derivatives, including those derived from direct substitution of a nitro group caused by O-attack of enolate. It was found the reactivity was lowered by an electron-withdrawing group on the carbonyl moiety. When α-nitroketone was employed as a substrate, three kinds of products were possibly formed; of these, only isoxazoline N-oxide was identified. This result indicates that the substituting ability of nitronate is higher than that of enolate for the direct SN2 substitution of a nitro group.

Biocompatible ionic liquid [Betaine][H2PO4] as a reusable catalyst for the substitution of xanthen-9-ol under solvent-free conditions

A cheap and biocompatible ionic liquid [Betaine][H2PO4] was found to be an efficient and reusable catalyst for the direct substitution reaction of xanthen-9-ol under solvent-free conditions.

PSIII-19 Effects of extrusion on true metabolizable energy, standardized amino acid digestibility, and chick growth assay of red and white sorghum

The aims of this experiment were to determine the energy value of raw grains [corn (CO), red sorghum (RS), white sorghum (WS)], in comparison to the energy values of the same grains post-extrusion. Cecectomized roosters were precision-fed up to 30g of either raw or extruded grains, then placed into individual cages with a collection tray underneath to catch excreta. After 48h, the excreta was collected and analyzed for N, gross energy, amino acids and dry matter. TMEn was highest (P < 0.05) for extruded WS (3.99 kcal/g) and lowest for raw WS (3.79 kcal/g), whereas extruded CO (3.89 kcal/g), and extruded RS (3.89 kcal/g) did not differ from raw RS (3.83 kcal/g) and raw CO (3.82 kcal/g). This indicates that there was greater utilization of the extruded grains compared to the raw, especially for WS. Amino acids were measured in the grains and the excreta to determine the digestibility. In addition to the rooster assay, a chick growth assay was conducted using Ross 308 male broiler chicks. The study lasted 14d, with average initial chick BW being 149.1g ± 0.048. The experimental diets consisted of inclusion of raw and extruded grains, respectively, added at direct substitution of corn. The results of the chick trial appear to be controversial to the rooster assay. The extruded CO and extruded WS diets were similar (P > 0.05) in weight gain compared to raw CO (660.84g, 665.70g, and 690.13g, respectively). Extruded WS had the greatest (P < 0.05) feed intake (973.3g), with raw RS having the lowest (847.44g). Raw CO had the greatest (P < 0.05) G:F, with extruded WS being lowest (P < 0.05); 754.63g and 683.75g, respectively. In conclusion, the chick growth assay showed superior weight gain in the extruded CO and WS diets, however, the extruded diets were least successful in G:F compared to the raw.

Nucleophilic Vinyl/Allyl, CF3 and CF2α Perfluoroalkyl Groups Substitution and/or E1CB Elimination Reactions of Fluorine Atom(s) in Organofluorinated Compounds

Direct substitution and elimination reactions of the fluorine atoms of difluoromethylene CF2α groups of nonspaced perfluoroalkyl chains, CF3 groups are very difficult to achieve. But, they become feasible with fluoro-alkenes, alkynes, imines or carbonyl derivatives, for which vinylic substitution and related carbanion-mediated pathways are available. In this review, we classify the major and unique fluorine substitution/elimination and rearrangement reactions and discuss their contribution to the synthesis of heterocyclic compounds.