Acid Research Articles

Digital Communication through Solids Using Magnetostriction

Digital communication through solid materials such as metals, ceramics, organic solids, or semiconductors has many applications. Only communication through metals has been attempted via ultrasonic waves. However, its performance is significantly hindered by echo interference. A way to enable communication through these solids is by the exploitation of magnetostriction. Magnetostriction is a property where a magnetic material changes its shape during the process of magnetization, essentially converting magnetic energy into kinetic energy. The kinetic energy produced by the magnetic material can then be taken through the solid media through which communication is intended to occur. The kinetic signal on the other side of the solid media could be converted to whatever type of energy is suitable for the application.This energy transduction channel, using magnetic energy and kinetic energy, can optimally be achieved through a soft magnetic material with high magnetostriction. A nickel-iron-cobalt based alloy was used to develop a material with a saturation magnetostriction over 200ppm, that can be electrodeposited out of an acidic aqueous chemistry. Initial high intrinsic stress in the deposited alloy was controlled with additives and altering the complexing, enabling consistent deposits of over a millimeter in thickness.The electrodeposited material’s performance is characterized and correlated to material properties such as alloy composition, microstructure, grain size, coercivity, magnetic saturation, Young’s Modulus, etc. The characterization methods used to analyze the magnetostrictive material and the effect of modulating plating parameters to control material properties will be presented. Additionally, the effect of annealing the material in an inert environment at varying temperatures and dwell times will be examined. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

LiBF4-Promoted Aromatic Fluorodetriazenation under Mild Conditions.

An efficient and mild fluorination method through LiBF4-promoted aromatic fluorodetriazenation of 3,3-dimethyl-1-aryltriazenes is developed. The reaction proceeds smoothly and tends to complete within 2 h in the absence of a protic acid or strong Lewis acid. This method tolerates a wide range of functional groups and affords the aryl fluoride products in moderate to excellent yields.

Diagnosis of table grapes sold at retail in Pelotas - RS

Table grapes are among the most consumed and commercialized fruits in the world and that has increased considerably in recent years. Table grape production in Pelotas is concentrated in the summer, and the grapes that are consumed in other seasons are from other states or even countries. The present work objective is to develop a research about the main table grapes sold in the retail of Pelotas and their qualitative characteristics. In each season of the year, samples were collected from all cultivars available in four previously selected retailers were carried out, with at least 2 bunches per cultivar, in order to analyze the following variables: bunch and berry mass, bunch length, length and diameter of berry, soluble solids (SS) and titratable acidity (AT). Of the grapes sold at retail in Pelotas, the fine ones represent more than 60% in all the periods studied when compared to American and hybrid grapes. The traditional varieties Italia, Red Globe, Niagara Rosada and Benitaka, are the most commonly found. Spring was the season in which the greatest diversity of cultivars was found. New cultivars such as Arra15®, Sable Seedless® and Sweet Celebration® are slowly being introduced. Some cultivars were outside the commercialization standard, in terms of maturity and bunch size.

Domino Approach for the Synthesis of Pyridinium Salts and 1,2,3,8a-Tetrahydroimidazo[1,2-a]pyridines from 2-Imidazolines and Propiolic Acid Esters.

Adducts of 1-alkyl-2-imidazolines and two molecules of alkyl propiolate, possessing an N-propargyl-β-enaminoester fragment, easily undergo a domino reaction to form pyridinium salts with β-(alkylammonio)ethyl group at the nitrogen atom in the presence of 2 equiv of a protic acid. Treatment of the above reaction mixture with a base gives 1,2,3,8a-tetrahydroimidazo[1,2-a]pyridines. Reaction of the latter compounds with acid chlorides affords pyridinium salts with β-(alkylamido)ethyl moiety at the nitrogen atom.

The Effectiveness of Acid and Base Android-Based Ludo Chemistry Game Media on Students' Cognitive Learning Outcomes

This research aims to analyze the level of effectiveness of the chemical ludo game on students’ cognitive learning outcomes in class XI SMA/MA. This method of research used a Quasi-Experimental with a non-equivalent control group design. The population of this research was students of class XI MIPA SMAN 3 Tualang. The sampling technique in this research was purposive, so class XI MIPA 1 was selected as the control class and XI MIPA 2 as the experiment class. The research instrument used in this study was the learning achievement test. The data analysis technique used was the N-Gain test, and hypothesis testing using the t-test. The results showed that students’ learning outcomes in the experimental class increased compared to the control class. It was evidenced by the average post-test score of 64.545 for the experimental class and 79.091 for the control class. The results of the N-Gain test for the experimental class were in the high category, namely 0.73 and for the control class, 0.57 in the medium category. The hypothesis test showed that at the real level α = 0.05 with dk = 78, the value of count (5.1413) > table (1.8044). Acid and base android-based ludo chemistry game media effectively improved cognitive learning outcomes of class XI SMA/MA students.

Ancient transcriptional regulators can easily evolve new pair-wise cooperativity

Cells regulate gene expression by the specific binding of transcription regulators to cis-regulatory sequences. Pair-wise cooperativity between regulators-whereby two different regulators physically interact and bind DNA in a cooperative manner-is common and permits complex modes of gene regulation. Over evolutionary timescales, the formation of new combinations of regulators represents a major source of phenotypic novelty, facilitating new network structures. How functional, pair-wise cooperative interactions arise between regulators is poorly understood, despite the abundance of examples in extant species. Here, we explore a protein-protein interaction between two ancient transcriptional regulators-the homeodomain protein Matα2 and the MADS box protein Mcm1-that was gained approximately 200 million y ago in a clade of ascomycete yeasts that includes Saccharomyces cerevisiae. By combining deep mutational scanning with a functional selection for cooperative gene expression, we tested millions of possible alternative evolutionary solutions to this interaction interface. The artificially evolved, functional solutions are highly degenerate, with diverse amino acid chemistries permitted at all positions but with widespread epistasis limiting success. Nonetheless, approximately ~45% of the random sequences sampled function as well or better in controlling gene expression than the naturally evolved sequence. From these variants (which are unconstrained by historical contingency), we discern structural rules and epistatic constraints governing the emergence of cooperativity between these two transcriptional regulators. This work provides a mechanistic basis for long-standing observations of transcription network plasticity and highlights the importance of epistasis in the evolution of new protein-protein interactions.

Development of Shigella conjugate vaccines targeting Shigella flexneri 2a and S. flexneri 3a using a simple platform-approach conjugation by squaric acid chemistry

There is a need for vaccines effective against shigella infection in young children in resource-limited areas. Protective immunity against shigella infection targets the O-specific polysaccharide (OSP) component of lipopolysaccharide. Inducing immune responses to polysaccharides in young children can be problematic, but high level and durable responses can be induced by presenting polysaccharides conjugated to carrier proteins. An effective shigella vaccine will need to be multivalent, targeting the most common global species and serotypes such as Shigella flexneri 2a, S. flexneri 3a, S. flexneri 6, and S. sonnei. Here we report the development of shigella conjugate vaccines (SCV) targeting S. flexneri 2a (SCV-Sf2a) and 3a (SCV-Sf3a) using squaric acid chemistry to result in single point sun-burst type display of OSP from carrier protein rTTHc, a 52 kDa recombinant protein fragment of the heavy chain of tetanus toxoid. We confirmed structure and demonstrated that these conjugates were recognized by serotype-specific monoclonal antibodies and convalescent sera of humans recovering from shigellosis in Bangladesh, suggesting correct immunological display of OSP. We vaccinated mice and found induction of serotype-specific OSP and LPS IgG responses, as well as rTTHc-specific IgG responses. Vaccination induced serotype-specific bactericidal antibody responses against S. flexneri, and vaccinated animals were protected against keratoconjunctivitis (Sereny test) and intraperitoneal challenge with virulent S. flexneri 2a and 3a, respectively. Our results support further development of this platform conjugation technology in the development of shigella conjugate vaccines for use in resource-limited settings.

What Is Wrong with Hyaluronic Acid Chemistry? A 15N/13C Solid-State NMR Re-Evaluation of Its Dopamine Conjugates

In this work, a systematic 15N/13C solid-state NMR investigation is performed on three dopamine (DA) conjugates of hyaluronic acid, considered in both its native (HA) and NaIO4-oxidized (HAOx) forms. Two of them, here named HAEDC-DA and HAOx-DA, have been previously introduced as covalent conjugates involving DA amine nitrogen: the former by EDC-mediated amide bond formation, and the latter by reaction of the Schiff base with the aldehyde moieties presumed to exist in HAOx. The third conjugate, HA-DA, is reported here for the first time; it is obtained by simply mixing hyaluronan with DA∙HCl at pH 5. The 15N ss-NMR spectra were found to be consistent in all the systems, and the DA molecules were found to be in their charged -NH3+ form, which contradicts the HAEDC-DA/HAOx-DA covalent bonding schemes proposed in the literature. The 13C ss-NMR results add useful new insights into the structure and interaction patterns of the conjugates. All of our findings are relevant for future practical applications, for instance in developing novel HA-based hydrogels. In addition, the present study demonstrates the importance of using the most appropriate analytical tools when investigating composite systems due to the complexity of hyaluronic acid conjugates. Solid-state NMR proved essential to answering the question in the title: actually, there is nothing wrong with hyaluronic acid chemistry; the claimed covalent bonds between DA and the HA(HAOx) chain do not exist in these systems, because the conditions for their formation do not hold in practice.

Two are not enough: synthetic strategies and applications of unnatural base pairs.

Nucleic acid chemistry is a rapidly evolving field, and the need for novel nucleotide modifications and artificial nucleotide building blocks for diagnostic and therapeutic use, material science or for studying cellular processes continues unabated. This review focusses on the development and application of unnatural base pairs as part of an expanded genetic alphabet. Not only recent developments in "nature-like" artificial base pairs are presented, but also current synthetic methods to get access to C-glycosidic nucleotides. Wide-ranging viability in synthesis is a prerequisite for the successful use of unnatural base pairs in a broader spectrum and will be discussed.

Post-harvest quality of potatoes (Solanum tuberosum L.) in response to hydrothermal treatment

The efficiency of hydrothermal treatment for the control of several bacterial diseases has been reported in some studies, but there are a lack of results on post-harvest changes resulting from this treatment. The objective of this work was to evaluate the post-harvest quality of potatoes submitted treated via hot water immersion. Potato tubers of the cultivar Ágata were immersed in 40, 50, 60, or 70ºC water for 1, 6, 11 and 21 minutes and evaluated for firmness of pulp (F), soluble solids (SS), pH, titratable acidity (AT), total soluble sugars (AST), reducing sugars (RA), non-reducing sugars (ANR), and starches at 1, 5, 10, 15, and 20 days of storage. The experiment was conducted in a completely randomized design. The means corresponding to the factors in question were analyzed using the Dunnett test (5%). It was possible to conclude that all hydrothermal treatments used here altered the acidity of the tubers. The treatments at 40°C at all immersion times; 50°C for 1, 6 and 11 minutes; and 60°C for 1 and 6 minutes provided a longer post-harvest tuber life.

Morpho-chemical characterization of loquat (Eriobotrya japonica Lindl.) genotypes

Morphological and chemical characterization of loquat genotypes were carried out to select superior genotypes between 2018 and 2021 in the coastal region of the Black Sea. In the study, the description of 70 genotypes with 20 g and above fruit weight of loquat, which is grown as chance seedlings in the mentioned region, was done. From the study, it was found soluble solids content (SSC) between 6.95 and 18.30%, acidity (AC) 0.22–0.82%, SSC/acidity ratio (SSCAcR) 16.39–67.68%, pH 2.85–4.94, dry matter ratio 47.29–54.73%, fresh weight (FreWe) 35.13–103.76 g, and dry weight (DW) 20.78–85.59 g. Considering morphological characteristics, leaf width (LWi) was found between 5.41 and 12.71 cm, leaf length (LL) 15.63–41.22 cm, leaf length/width ratio (LLWR) 1.37–5.57%, petiole diameter (PD) 3.74–8.00 mm, petiole length (PL) 8.87–46.72 mm, and leaf area between 77.59 and 312.92 cm2. A strongly negative correlation was observed between SSCAcR and AC (0.836). In contrast, significant positive correlation was found between DW and FreWe (0.636), pH and SSCAcR (0.544). In the case of chemical characteristics, the percentage of variances of components 1 to 5 respectively observed (29.13%, 20.37%, 14.96%, 10.84%, and 10.22%), which cumulatively encompassed 85.54% of variances. In the case of morphological characteristics, the correlation between LWi and LLWR (− 0.670), LL and LLWR (0.597), LWi and PD (0.311), LLWR and PD (− 0.312), PD and PL (− 0.260) obtained significant at P < 0.05. The percentage of variance explained by each principle component from components 1 to 4 respectively observed (28.54%, 22.18%, 16.06%, and 10.70%), which cumulatively encompassed 77.50% of variances. Finally, five genotypes, including GN10, GN14, GN50, GN68, and GN69, were determined superior among 70 genotypes. Based on the high “Weighed Rating” scores they received, they were suggested for further consideration.

Valorisation of spent tire rubber as carbon adsorbents for Pb(II) and W(VI) in the framework of a Circular Economy

Spent tire rubber-derived chars and their corresponding H3PO4 and CO2-activated chars were used as adsorbents in the recovery of Pb(II) ion and (W(VI)) oxyanion from synthetic solutions. The developed chars (both raw and activated) were thoroughly characterized to have insight about their textural and surface chemistry properties. H3PO4-activated chars presented lower surface areas than the raw chars and an acidic surface chemistry which affected the performance of these samples as they showed the lowest removals of the metallic ions. On the other hand, CO2-activated chars presented increased surface areas and increased mineral content compared to the raw chars, having presented higher uptake capacities for both Pb(II) (103–116 mg/g) and W(VI) (27–31 mg/g) ions. Cation exchange with Ca, Mg and Zn ions was appointed as a mechanism for Pb removal, as well as surface precipitation in the form of hydrocerussite (Pb3(CO3)2(OH)2). W(VI) adsorption might have been ruled by strong electrostatic attractions between the negatively charged tungstate species and the highly positively charged carbons’ surface.The results shown in this work allow concluding that the valorisation of spent tire rubber through pyrolysis and the subsequent activation of the obtained chars is an alternative and a feasible option to generate adsorbent materials with a high uptake capacity of critical metallic elements.

The Expanded Central Dogma: Genome Resynthesis, Orthogonal Biosystems, Synthetic Genetics.

Synthetic biology seeks to probe fundamental aspects of biological form and function by construction [i.e., (re)synthesis] rather than deconstruction (analysis). In this sense, biological sciences now follow the lead given by the chemical sciences. Synthesis can complement analytic studies but also allows novel approaches to answering fundamental biological questions and opens up vast opportunities for the exploitation of biological processes to provide solutions for global problems. In this review, we explore aspects of this synthesis paradigm as applied to the chemistry and function of nucleic acids in biological systems and beyond, specifically, in genome resynthesis, synthetic genetics (i.e., the expansion of the genetic alphabet, of the genetic code, and of the chemical make-up of genetic systems), and the elaboration of orthogonal biosystems and components.

Surface Confinement of Finite-Size Water Droplets for SO3 Hydrolysis Reaction Revealed by Molecular Dynamics Simulations Based on a Machine Learning Force Field

As an important source for sulfuric acid in the atmosphere, hydrolysis of sulfur trioxide (SO3) takes place with water clusters of sizes from several molecules to several nanometers, resulting in various final products, including neutral (H2SO4)-(H2O) clusters and ionic (HSO4)--(H3O)+ clusters. The diverse products may be due to the ability of proton transfer and the formation of hydrated ions for water cluster of finite sizes, especially the sub-micrometer ones. However, the detailed molecular-level mechanism is still unclear due to the lack of available characterization and simulations tools. Here, we developed a quantum chemistry-level machine learning (ML) model to simulate the hydrolysis of SO3 with water clusters of sizes up to nanometers. The simulation results demonstrate diverse reaction paths taking place between SO3 and water clusters of different sizes. Generally, neutral (H2SO4)-(H2O) clusters are preferred by water clusters of ultra-small size, and a loop structure-mediated mechanism with SO3(H2O)n≤4 structures and a non-loop structure-mediated mechanism with structure relaxation are observed. As the water cluster size increases to (H2O)8, a (HSO4)--(H3O)+ ion-pair product emerges; and the Eigen-Zundel ion conversion-like proton transfer mechanism takes place and stabilizes the ion pairs. As the water cluster sizes further increase beyond several nanometers ((H2O)n≥32), the (SO4)2-[(H3O)+]2 ion-pair product appears. The reason could be that the surface of these water clusters is large enough to screen Coulomb repulsion between two tri-coordinated ion-pair complexes. These findings would provide new perspectives for understanding SO3 hydrolysis in the real atmosphere and sulfuric acid chemistry in atmospheric aerosols.

Protic Amine Carboxylic Acid Ionic Liquids Additives Regulate α-FAPbI3 Phase Transition for High Efficiency Perovskite Solar Cells.

The α-phase formamidinium lead tri-iodide (α-FAPbI3 ) has become the most promising photovoltaic absorber for perovskite solar cells (PSCs) due to its outstanding semiconductor properties and astonishing high efficiency. However, the incomplete crystallization and phase transition of α-FAPbI3 substantially undermine the performance and stability of PSCs. In this work, a series of the protic amine carboxylic acid ion liquids are introduced as the precursor additives to efficiently regulate the crystal growth and phase transition processes of α-FAPbI3 . The MA2 Pb3 I8 ·2DMSO phase is inhibited in annealing process, which remarkably optimizes the phase transition process of α-FAPbI3 . It is noted that the functional groups of carboxyl and ammonium passivate the undercoordinated lead ions, halide vacancies, and organic vacancies, eliminating the deleterious nonradiative recombination. Consequently, the small-area devices incorporated with 2% methylammonium butyrate (MAB) and 1.5% n-butylammonium formate (BAFa) in perovskite show champion efficiencies of 25.10% and 24.52%, respectively. Furthermore, the large-area modules (5cm × 5cm) achieve PCEs of 21.26% and 19.27% for MAB and BAFa additives, indicating the great potential for commercializing large-area PSCs.

Linker-Free Synthesis of Antimicrobial Peptides Using a Novel Cleavage Reagent: Characterisation of the Molecular and Ionic Composition by nanoESI-HR MS.

The efficient preparation of novel bioactive peptide drugs requires the availability of reliable and accessible chemical methodologies together with suitable analytical techniques for the full characterisation of the synthesised compounds. Herein, we describe a novel acidolytic method with application to the synthesis of cyclic and linear peptides involving benzyl-type protection. The process consists of the in situ generation of anhydrous hydrogen bromide and a trialkylsilyl bromide that acts as protic and Lewis acid reagents. This method proved to be useful to effectively remove benzyl-type protecting groups and cleave Fmoc/tBu assembled peptides directly attached to 4-methylbenzhydrylamine (MBHA) resins with no need for using mild trifluoroacetic acid labile linkers. The novel methodology was successful in synthesising three antimicrobial peptides, including the cyclic compound polymyxin B3, dusquetide, and RR4 heptapeptide. Furthermore, electrospray mass spectrometry (ESI-MS) is successfully used for the full characterisation of both the molecular and ionic composition of the synthetic peptides.

Boronic Acid Resin for Selective Immobilization of Canonically Encoded Proteins

The use of transition-metal-mediated boronic acid chemistry presents a novel method of protein immobilization on a solid support. This is a one-step method that site-selectively immobilizes pyroglutamate-histidine (pGH)-tagged proteins. Herein, we describe the synthesis of alkenylboronic acid-functionalized poly(ethylene glycol) acrylamide (PEGA) resin and its subsequent reactions with pGH-tagged proteins to produce covalent linkages. The selectivity of immobilization is demonstrated within fluorescent studies, model mixtures, and lysates.

Eco-friendly nitration of acetanilide over MCM-41-supported CeCuCoOx catalyst: A solid acidic catalysis strategy

The development of solid acidic catalyst is of great significance to the safe, controllable, efficient and environment-friendly nitration of aromatics. Herein, a series of trimetallic supported catalysts were obtained by the equivalent-volumetic impregnation method. In the as-prepared Ce4Cu6Co0.5Ox/MCM-41 catalyst with strong acidic sites, the metal oxide particles mainly distributed in a form of nanowires in MCM-41 molecular sieve channels. And, the Ce4Cu6Co0.5Ox/MCM-41 catalyst exhibited an excellent catalytic performance for the nitration of acetanilide with equivalent dilute nitric acid as a nitration reagent. Surprisingly, 91% conversion of acetanilide with 91.6% selectivity to mono-nitroacetanilide was achieved. The nitration of acetanilide obviously exhibited a typical ortho-para nitration effect of the aromatics. Furthermore, an excellent stability and acceptable reusability proved a potential to replace the nitration system of concentrated acid in chemical industry. The Lewis acid sites of Ce4Cu6Co0.5Ox/MCM-41 solid acid catalyst can act a similar role to a strong protic acid in mixed acid system, which can polarize nitric acid molecules to form active NO2+ reagents. Meanwhile, the abundant strong acidic sites of solid acidic Ce4Cu6Co0.5Ox in MCM-41 channels are significantly conducive to the sorption and activation of the reactants. The present work provides a prospective strategy for constructing a solidic acid catalyst with an eco-friendly nitration of aromatics.

Changes in Acidity Levels in the Gastric Tube After Esophagectomy for Esophageal Cancer.

Reflux esophagitis and gastric tube ulcer sometimes cause severe clinical problems in patients undergoing esophagectomy with gastric tube reconstruction. We previously reported that acidity in the gastric tube was decreased for 1 year after esophagectomy, and that lower acidity levels were associated with Helicobacter pylori (H. pylori) infection. However, the long-term changes in gastric acidity remain unknown. We aimed to investigate the long-term changes in gastric acidity after surgery. Eighty-nine patients who underwent esophagectomy with gastric tube reconstruction for esophageal cancer were analyzed. They underwent 24-hour pH monitoring, serum gastrin measurement, and H. pylori infection examination before surgery, at 1 month, 1 year, and 2 years after surgery. The gastric acidity at 1 month and 1 year after surgery was significantly lower than that before surgery (p=0.003, p=0.003). However, there was no difference in gastric acidity before and 2 years after surgery. The gas tric acidity in H. pylori-infected patients was significantly lower in comparison to non-infected patients at each time point (p=0.0003, p<0.0001, p<0.0001, p<0.0001, respectively). In H. pylori-infected patients, gastric acid ity was decreased for 1 year after surgery, and recovered within 2 years after surgery. However, no significant differences were observed in the acidity levels of non-infected patients during the 2-year follow-up period. The serum gastrin level increased after esophagectomy. The acidity levels in the gastric tube recovered within 2 years after surgery. Periodic endoscopy examination is recommended for early detection of acid-related disease, such as reflux esophagitis or gastric tube ulcer, after esophagectomy with gastric tube reconstruction.

1,3,5,8-Tetrasubstituted 1,3,4-Benzotriazepin-2-one Scaffolds for β-Turn Mimicry without Stereogenic Carbon Centers: Synthesis and Conformational Analysis.

Topological mimicry of peptide β-turn secondary structures has been investigated using a 1,3,5,8-tetrasubstituted 1,3,4-benzotriazepin-2-one scaffold. Approaches were conceived for the synthesis of tetrasubstituted benzotriazepinones from 4-acetyl-3-aminobenzoate based on aza-amino acid chemistry and different orthogonal protection strategies. Installation of an 8-position carboxylate on the aromatic ring enabled a diverse array of substituents to be introduced for mimicry of the i-position residue. Benzotriazepin-2-one crystallization and X-ray analysis demonstrated that in spite the absence of a stereogenic carbon center, the scaffold could serve as type I and I' β-turn mimics, because pyramidalization of the N3-nitrogen in the benzotriazepin-2-one provides potential for adoptive chirality. 1,3,5,8-Tetrasubstituted 1,3,4-benzotriazepin-2-one scaffolds offer interesting potential for the cost-effective synthesis of nonpeptide β-turn surrogates for peptide mimicry in various recognition events.