Compatible Conditions Research Articles

Stereoselective Synthesis of 1‐Arylpropan‐2‐amines from Allylbenzenes through a Wacker‐Tsuji Oxidation‐Biotransamination Sequential Process

AbstractHerein, a sequential and selective chemoenzymatic approach is described involving the metal‐catalysed Wacker‐Tsuji oxidation of allylbenzenes followed by the amine transaminase‐catalysed biotransamination of the resulting 1‐arylpropan‐2‐ones. Thus, a series of nine optically active 1‐arylpropan‐2‐amines were obtained with good to very high conversions (74–92%) and excellent selectivities (>99% enantiomeric excess) in aqueous medium.The Wacker‐Tsuji reaction has been exhaustively optimised searching for compatible conditions with the biotransamination experiments, using palladium(II) complexes as catalysts and iron(III) salts as terminal oxidants in aqueous media. The compatibility of palladium/iron systems for the chemical oxidation with commercially available and made in house amine transaminases was analysed, finding ideal conditions for the development of a general and stereoselective cascade sequence. Depending on the selectivity displayed by selected amine transaminase, it was possible to produce both 1‐arylpropan‐2‐amines enantiomers under mild reaction conditions, compounds that present therapeutic properties or can be employed as synthetic intermediates of chiral drugs from the amphetamine family.magnified image

Arylation Chemistry for Bioconjugation.

Bioconjugation chemistry has been used to prepare modified biomolecules with functions beyond what nature intended. Central to these techniques is the development of highly efficient and selective bioconjugation reactions that operate under mild, biomolecule compatible conditions. Methods that form a nucleophile-sp2 carbon bond show promise for creating bioconjugates with new modifications, sometimes resulting in molecules with unparalleled functions. Here we outline and review sulfur, nitrogen, selenium, oxygen, and carbon arylative bioconjugation strategies and their applications to modify peptides, proteins, sugars, and nucleic acids.

The effect of stress boundary conditions on fluid‐driven fracture propagation in porous media using a phase‐field modeling approach

SummaryA phase‐field approach for fluid‐driven fracture propagation in porous media with varying constant compatible stress boundary conditions is discussed and implemented. Since crack opening displacement, fracture path, and stress values near the fracture are highly dependent on the given boundary conditions, it is crucial to take into account the impact of in situ stresses on fracturing propagation for realistic applications. We illustrate several numerical examples that include the effects of different boundary conditions on the fracture propagation. In addition, an example using realistic boundary conditions from a reservoir simulator is included to show the capabilities of our computational framework.

Diplomats' Mystery Illness and Pulsed Radiofrequency/Microwave Radiation.

Importance: A mystery illness striking U.S. and Canadian diplomats to Cuba (and now China) "has confounded the FBI, the State Department and US intelligence agencies" (Lederman, Weissenstein, & Lee, 2017). Sonic explanations for the so-called health attacks have long dominated media reports, propelled by peculiar sounds heard and auditory symptoms experienced. Sonic mediation was justly rejected by experts. We assessed whether pulsed radiofrequency/microwave radiation (RF/MW) exposure can accommodate reported facts in diplomats, including unusual ones. Observations: (1) Noises: Many diplomats heard chirping, ringing or grinding noises at night during episodes reportedly triggering health problems. Some reported that noises were localized with laser-like precision or said the sounds seemed to follow them (within the territory in which they were perceived). Pulsed RF/MW engenders just these apparent "sounds" via the Frey effect. Perceived "sounds" differ by head dimensions and pulse characteristics and can be perceived as located behind in or above the head. Ability to hear the "sounds" depends on high-frequency hearing and low ambient noise. (2) Signs/symptoms: Hearing loss and tinnitus are prominent in affected diplomats and in RF/MW-affected individuals. Each of the protean symptoms that diplomats report also affect persons reporting symptoms from RF/MW: sleep problems, headaches, and cognitive problems dominate in both groups. Sensations of pressure or vibration figure in each. Both encompass vision, balance, and speech problems and nosebleeds. Brain injury and brain swelling are reported in both. (3) Mechanisms: Oxidative stress provides a documented mechanism of RF/MW injury compatible with reported signs and symptoms; sequelae of endothelial dysfunction (yielding blood flow compromise), membrane damage, blood-brain barrier disruption, mitochondrial injury, apoptosis, and autoimmune triggering afford downstream mechanisms, of varying persistence, that merit investigation. (4) Of note, microwaving of the U.S. embassy in Moscow is historically documented. Conclusions and relevance: Reported facts appear consistent with pulsed RF/MW as the source of injury in affected diplomats. Nondiplomats citing symptoms from RF/MW, often with an inciting pulsed-RF/MW exposure, report compatible health conditions. Under the RF/MW hypothesis, lessons learned for diplomats and for RF/MW-affected civilians may each aid the other.

Nd2-<italic> <sub>x</sub> </italic>Ce<italic> <sub>x</sub> </italic>CuO4±δ Ultrathin Films Crystalline Properties

Ultrathin films of the electron-doped compound Nd2− x Ce x CuO4±δ (NCCO) were realized by dc sputtering technique. The films were grown both on (001)-oriented SrTiO3 and nonstoichiometric SrTiO3 with Ti-rich defects. Also, the NCO parent compound, namely Nd2CuO4, was used as buffer layer to improve the crystalline properties because of the very small lattice parameter mismatch, as well as compatible depositions conditions, compared to NCCO. The morphological and structural characterization were carried out on several samples, by means of surface analysis techniques and X-ray diffraction, in order to optimize the growth procedure.

Peptide‐Gold Nanoparticle Conjugates as Sequential Cascade Catalysts

AbstractCombining bio‐ and chemocatalysis in one pot is a challenging task due to the necessity to ensure compatible reaction conditions, as well as reagent tolerance, for the catalytic components. Here we present a peptide‐gold nanoparticle conjugate that combines esterase (biocatalysis) and hydrogenation (chemocatalysis) activities under the same set of aqueous reaction conditions. The self‐assembled peptide‐monolayer acts as an esterase mimic and shows positive cooperativity in substrate binding, an important feature used by nature to regulate catalytic activities of enzymes. The gold nanoparticle surface catalyzes the reduction of a nitro‐containing substrate to an amine product. This study opens up a new avenue in the design of peptide‐metal nanoparticle catalysts with enzyme‐like properties for efficient one‐pot reactions.

Single-step conversion of lignin monomers to phenol: Bridging the gap between lignin and high-value chemicals

Transformation of lignin into high-value chemicals is hampered by the complexity of monomers obtained from lignin depolymerization. Here we report a strategy, composed of hydro-demethoxylation and de-alkylation reactions, that is able to chemically converge various lignin-derived phenolic monomers into phenol in a single-step. Using 2-methoxy-4-propylphenol as a model compound, Pt/C exhibited the best performance in hydro-demethoxylation reaction affording >80% 4-propylphenol from 2-methoxy-4-propylphenol, while H-ZSM-5 was identified as the most suitable catalyst for de-alkylation, achieving 83% yield of phenol from 4-propylphenol. Since the two catalysts operate under compatible conditions, combining the two catalysts to simultaneously promote both hydro-demethoxylation and de-alkylation reactions was achieved. Configuration of how to organize the catalysts is a critical parameter, where the physical mixture of the two was most effective, providing over 60% phenol from 2-methoxy-4-propylphenol in a single-step.

Visible‐Light Induced Radical Silylation for the Synthesis of Dibenzosiloles via Dehydrogenative Cyclization

AbstractA visible‐light induced radical silylation to dibenzosiloles from biarylhydrosilanes is described. The products were obtained in satisfactory yields under mild and water/air compatible conditions, providing an efficient and practical method for the synthesis of difunctionalized siloles by using a cheap organic dye photocatalyst. The method is tolerated by a wide range of functional groups and has a broad substrate scope. Light/dark experiments and quantum yield measurements provided support for a photocatalytic pathway rather than a chain process.magnified image

Some Fixed Point Results in Complete Menger Spaces with Occasionally Weakly Compatible Conditions

Some Fixed Point Results in Complete Menger Spaces with Occasionally Weakly Compatible Conditions

Development of a thermostable nanoemulsion adjuvanted vaccine against tuberculosis using a design-of-experiments approach

BackgroundAdjuvants have the potential to increase the efficacy of protein-based vaccines but need to be maintained within specific temperature and storage conditions. Lyophilization can be used to increase the thermostability of protein pharmaceuticals; however, no marketed vaccine that contains an adjuvant is currently lyophilized, and lyophilization of oil-in-water nanoemulsion adjuvants presents a specific challenge. We have previously demonstrated the feasibility of lyophilizing a candidate adjuvanted protein vaccine against Mycobacterium tuberculosis (Mtb), ID93 + GLA-SE, and the subsequent improvement of thermostability; however, further development is required to prevent physicochemical changes and degradation of the TLR4 agonist glucopyranosyl lipid adjuvant formulated in an oil-in-water nanoemulsion (SE).Materials and methodsIn this study, we took a systematic approach to the development of a thermostable product by first identifying compatible solution conditions and stabilizing excipients for both antigen and adjuvant. Next, we applied a design-of-experiments approach to identify stable lyophilized drug product formulations.ResultsWe identified specific formulations that contain disaccharide or a combination of disaccharide and mannitol that can achieve substantially improved thermostability and maintain immunogenicity in a mouse model when tested in accelerated and real-time stability studies.ConclusionThese efforts will aid in the development of a platform formulation for use with other similar vaccines.

Simultaneous impacts of MHD and variable wall temperature on transient mixed Casson nanofluid flow in the stagnation point of rotating sphere

A numerical analysis is provided to scrutinize time-dependent magnetohydrodynamics (MHD) free and forced convection of an electrically conducting non-Newtonian Casson nanofluid flow in the forward stagnation point region of an impulsively rotating sphere with variable wall temperature. A single-phase flow of nanofluid model is reflected with a number of experimental formulae for both effective viscosity and thermal conductivity of nanofluid. Exceedingly nonlinear governing partial differential equations (PDEs) subject to their compatible boundary conditions are mutated into a system of nonlinear ordinary differential equations (ODEs). The derived nonlinear system is solved numerically with implementation of an implicit finite difference procedure merging with a technique of quasi-linearization. The controlled parameter impacts are clarified by a parametric study of the entire flow regime. It is depicted that from all the exhibited nanoparticles, Cu possesses the best convection. The surface heat transfer and surface shear stresses in the x - and z -directions are boosted with maximizing the values of nanoparticle solid volume fraction φ and rotation λ . Besides, as both the surface temperature exponent n and the Casson parameter γ upgrade, an enhancement of the Nusselt number is given.

Enterocolitis Neutropénica en pacientes pediátricos con Leucemia Linfoide Aguda con recaída o refractariedad de su enfermedad de base, durante el período 2016-2017.

Introducción: La enterocolitis neutropénica se define como un proceso inflamatorio multifactorial propio de pacientes neutropénicos, caracterizado por el daño trasmural principalmente a nivel del ciego, aunque puede afectar otras áreas como el colon ascendente e íleo. Debido a la dificultad en el diagnóstico y las complicaciones que se presentan se decide realizar un estudio descriptivo de esta patología, sus métodos diagnósticos, manejo y principales complicaciones asociadas. Métodos: Entre octubre del año 2016 y septiembre del año 2017, se realizó un estudio retrospectivo y descriptivo de pacientes diagnosticados de Leucemia Linfoide Aguda (LLA) con recaída o refractariedad de su enfermedad de base que presentaron cuadros compatibles clínica y radiográficamente con enterocolitis neutropénica. El estudio fue realizado en el servicio de oncología pediátrica del Instituto Oncológico Nacional “Dr. Juan Tanca Marengo”, Solca Guayaquil. Resultados: Se identificaron 21 casos, de los cuales 17 (80.95%) fueron hombres. Los principales síntomas presentados fueron dolor abdominal, diarrea y fiebre, en el contexto de pacientes neutropénicos, quienes habían recibido tratamiento quimioterápico en los días previos. La ecografía abdominal fue utilizada en todos los casos junto con tomografía abdominal realizada en 6 pacientes como método complementario al diagnóstico. Ningún paciente fue intervenido quirúrgicamente. Todos los pacientes se manejaron de forma conservadora con una evolución favorable. Conclusión: Debe sospecharse esta patología en todo paciente que presente sintomatología compatible con dolor abdominal, asociando fiebre o diarrea y que hubiere recibido tratamiento quimoterápico en los días previos. Solicitando de forma urgente los estudios complementarios necesarios para el diagnóstico y debiendo ser manejado de forma integral. Reservándose el tratamiento quirúrgico ante cuadros con una evolución desfavorable.

Different-Length Hydrazone Activated Polymers for Plasmid DNA Condensation and Cellular Transfection.

The recent advances in genetic engineering demand the development of conceptually new methods to prepare and identify efficient vectors for the intracellular delivery of different nucleotide payloads ranging from short single-stranded oligonucleotides to larger plasmid double-stranded circular DNAs. Although many challenges still have to be overcome, polymers hold great potential for intracellular nucleotide delivery and gene therapy. We here develop and apply the postpolymerization modification of polyhydrazide scaffolds, with different degree of polymerization, for the preparation of amphiphilic polymeric vehicles for the intracellular delivery of a circular plasmid DNA. The hydrazone formation reactions with a mixture of cationic and hydrophobic aldehydes proceed in physiologically compatible aqueous conditions, and the resulting amphiphilic polyhydrazones are directly combined with the biological cargo without any purification step. This methodology allowed the preparation of stable polyplexes with a suitable size and zeta potential to achieve an efficient encapsulation and intracellular delivery of the DNA cargo. Simple formulations that performed with efficiencies and cell viabilities comparable to the current gold standard were identified. Furthermore, the internalization mechanism was studied via internalization experiments in the presence of endocytic inhibitors and fluorescence microscopy. The results reported here confirmed that the polyhydrazone functionalization is a suitable strategy for the screening and identification of customized polymeric vehicles for the delivery of different nucleotide cargos.

Behavior of the Paleosecular Variation During the Permian‐Carboniferous Reversed Superchron and Comparisons to the Low Reversal Frequency Intervals Since Precambrian Times

AbstractWe investigated the (paleo)latitudinal dependence of angular dispersion sets of virtual geomagnetic poles (VGPs) for the Permian‐Carboniferous Reversed Superchron (PCRS: 262–318 Ma). In order to analyze the paleosecular variation during this period, we prepared different paleomagnetic data sets from scientific databases and recent literature, based on selection criteria which provided high degree of refinement. Model G of McFadden et al. (1988) was fitted to the VGP dispersion data, providing the shape parameters a and b, which were further compared with similar results for the Cretaceous Normal Superchron (CNS) and other periods of different geomagnetic reversal rates throughout the last 3 Ga. Our results indicate high similarity between the angular VGP dispersion from the PCRS and CNS (a low VGP dispersion at low paleolatitudes, and strong paleolatitudinal dependence), in contrasting difference for periods of higher reversal rates (the last 5 Ma). Despite the geodynamic differences related to both Phanerozoic superchrons, such evidence could point out similar heat flux conditions in the CMB, which may favor compatible stability conditions throughout these magnetozones. Notably, two additional observations which arose from the shape parameters relations for both Phanerozoic superchrons and Precambrian data sets demand further investigation: (i) a pattern of increase for the b/a ratio throughout the 0.5–1.6 Ga interval was observed, which could be partially explained by the Maya Superchron, recently proposed by Gallet et al. (2012) and (ii) the b × a relationship for both Phanerozoic superchrons and the 2.45–2.82 Ga interval pointed to the presence of one or more long‐term magnetozones throughout the Paleoproterozoic.

Whole‐Cell Cascade Biotransformations for One‐Pot Multistep Organic Synthesis

AbstractPerforming one‐pot multi‐catalysis reactions is a revolutionary tool for multistep synthesis, representing a fast‐developing theme in catalysis field. To develop cascade reactions, enzymes are ideal catalysts due to their compatible reaction conditions. The implementation of enzyme cascades in recombinant microbial cells provides easily available self‐replicating catalysts for facile one‐pot biotransformations to produce a wide range of high‐value (chiral) chemicals. In this minireview, we summarize the recent development of whole‐cell cascade biotransformations according to the types of substrates, ranging from petrochemicals to biochemicals. Furthermore, we provide general instructions for the establishment of in vivo enzyme cascades, discuss the encountered problems and the corresponding solutions, and highlight the promising directions for future advance.

Static and dynamic behaviour of nonlocal elastic bar using integral strain-based and peridynamic models

The static and dynamic behaviour of a nonlocal bar of finite length is studied in this paper. The nonlocal integral models considered in this paper are strain-based and relative displacement-based nonlocal models; the latter one is also labelled as a peridynamic model. For infinite media, and for sufficiently smooth displacement fields, both integral nonlocal models can be equivalent, assuming some kernel correspondence rules. For infinite media (or finite media with extended reflection rules), it is also shown that Eringen's differential model can be reformulated into a consistent strain-based integral nonlocal model with exponential kernel, or into a relative displacement-based integral nonlocal model with a modified exponential kernel. A finite bar in uniform tension is considered as a paradigmatic static case. The strain-based nonlocal behaviour of this bar in tension is analyzed for different kernels available in the literature. It is shown that the kernel has to fulfil some normalization and end compatibility conditions in order to preserve the uniform strain field associated with this homogeneous stress state. Such a kernel can be built by combining a local and a nonlocal strain measure with compatible boundary conditions, or by extending the domain outside its finite size while preserving some kinematic compatibility conditions. The same results are shown for the nonlocal peridynamic bar where a homogeneous strain field is also analytically obtained in the elastic bar for consistent compatible kinematic boundary conditions at the vicinity of the end conditions. The results are extended to the vibration of a fixed–fixed finite bar where the natural frequencies are calculated for both the strain-based and the peridynamic models.

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids - tutorial.

The structural characterization of non-covalent complexes between nucleic acids and small molecules (ligands) is of a paramount significance to bioorganic research. Highly informative methods about nucleic acid/ligand complexes such as single crystal X-ray diffraction or NMR spectroscopy cannot be performed under biologically compatible conditions and are extensively time consuming. Therefore, in search for faster methods which can be applied to conditions that are at least similar to the naturally occurring ones, a set of polarization spectroscopy methods has shown highly promising results. Electronic circular dichroism (ECD) is the most commonly used method for the characterization of the helical structure of DNA and RNA and their complexes with ligands. Less common but complementary to ECD, is flow-oriented linear dichroism (LD). Other methods such as vibrational CD (VCD) and emission-based methods (FDCD, CPL), can also be used for suitable samples. Despite the popularity of polarization spectroscopy in biophysics, aside several highly focused reviews on the application of these methods to DNA/RNA research, there is no systematic tutorial covering all mentioned methods as a tool for the characterization of adducts between nucleic acids and small ligands. This tutorial aims to help researchers entering the research field to organize experiments accurately and to interpret the obtained data reliably.

A Generalized Bilateral Trading Model

In the bilateral trading model developed by Myerson [1], an ex post efficient mechanism that satisfies incentive compatibility and individual rationality has been proved to be not existed. This paper is aimed at the discussion of modified bilateral trading model where the buyer and seller’s valuations for the object are assumed to be not independent. Under such assumption, we concern about the existence of an ex post efficient mechanism satisfying individual compatible and individual rational conditions. We will give a necessary condition of such mechanism, not precisely though, to identify the existence. At the end of this paper, we provide some empirical evidences about the non-independent assumption and suggest some directions for further research, both empirical and theoretical.

Fixed Point Results of Contractive Mappings by Altering Distances and C-Class Functions in b-Dislocated Metric Spaces

In this work, we recall definition of functions called as C-class and use the concepts of dislocated metric, b-dislocated metric, altering distance function. We prove some coincidence, fixed and common fixed point results for two pairs of weakly compatible mappings under-contractive conditions and contractive conditions depended on another function T. Our theorems extend and generalize related results in the literature.

Opportunities and challenges for combining chemo- and biocatalysis

The past decade has seen a substantial increase in successful examples of the combination of chemo- and biocatalysis for multistep syntheses. This is driven by obvious advantages such as higher yields, decreased costs, environmental benefits and high selectivity. On the downside, efforts must be undertaken to combine the divergent reaction conditions, reagent tolerance and solvent systems of these ‘different worlds of catalysis’. Owing to progress in enzyme discovery and engineering, as well as in the development of milder and more compatible conditions for operating with various chemocatalysts, many historical limitations can already be overcome. This Review highlights the opportunities available in the chemical space of combined syntheses using prominent examples, but also discusses the current challenges and emerging solutions, keeping in mind the fast progress in transition metal-, organo-, photo-, electro-, hetero- and biocatalysis. Chemical and biological catalysts provide distinct advantages and disadvantages to the synthetic chemist. This Review focuses on efforts to combine chemo- and biocatalysts, outlining the opportunities achievable by this approach and also efforts to overcome any incompatibilities between these different systems.