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1.
Carbohydr Polym ; 300: 120253, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36372510

RESUMO

In this work, a systematic coupling study of silane coupling agent between starch and epoxidized soybean oils (ESO) was carried out. Starch was modified by 3-aminopropyl trimethoxy silane (APMS) with various contents of NaOH. The APMS-modified starch was incorporated with ESO to synthesize the bioplastics by solution casting. As demonstrated by the FTIR spectra, the hydrogen bond interactions among starch molecules were inhibited by the modification. This outcome provided higher interaction and compatibility of starch with ESO, as confirmed by FESEM. TGA showed that the thermal stability of starch decreased considerably after the silylation. In contrast, the produced bioplastics with silylated starch exhibited higher thermal stability than the control sample. Regarding the bioplastics, an obvious increase of tensile strength from 5.78 MPa to 9.29 MPa was obtained. This work suggested a simple and effective modification technique by APMS to improve compatibility of starch/ESO-based bioplastics with superior mechanical and thermal properties.


Assuntos
Manihot , Óleo de Soja , Óleo de Soja/química , Manihot/química , Silanos , Amido/química , Resistência à Tração
2.
Oper Dent ; 47(6): E264-E272, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36322401

RESUMO

OBJECTIVES: To evaluate the bond strength of a resin luting agent to a lithium disilicate glass-ceramic after the use of different fit-checking materials and cleaning protocols. METHODS AND MATERIALS: Two hundred and forty-two (242) ceramic specimens were etched with 5% hydrofluoric acid for 20 seconds and distributed into 22 groups (n=10), in total. Four (4) groups were created based on fit-checking material and that had no following cleaning protocol: no fit-checking material used (control group); articulating paper; articulating spray; and fit-checker liquid. For each fit-checking material (3), 6 cleaning protocols were tested creating an additional 18 groups (n=10): air/water spray; 70% alcohol (ethanol); acetone; 35% phosphoric acid; 5% hydrofluoric acid; and a commercially available cleaning paste (Ivoclean, Ivoclar Vivadent). Silane and bonding resin were applied to all ceramic surfaces. Resin luting agent cylinders (1 mm in diameter) were created using silicone matrices, light-cured, and specimens were stored in deionized water at 37°C for 24 hours. Microshear bond strength test (µSBS) was performed on a universal testing machine (DL 500, EMIC) at a crosshead speed of 1 mm/min until failure. Results were statistically analyzed using ANOVA and Tukey's test (α=0.05). RESULTS: Articulating paper and fit-checker liquid, when not properly removed, negatively affected the bond strength (p<0.05). None of the tested cleaning protocols were effective for articulating paper (p<0.05). There was no significant difference in bond strength after the cleaning protocols between articulating spray and fit-checker liquid when compared to the control group (no contamination) (p>0.05). CONCLUSION: The cleaning protocols tested can effectively restore the bond strength of resin luting agents to lithium disilicate ceramics that were exposed to articulating spray or fit-checker liquid. The use of articulating paper is not recommended for fit-checking indirect lithium disilicate restorations.


Assuntos
Colagem Dentária , Ácido Fluorídrico , Ácido Fluorídrico/química , Colagem Dentária/métodos , Análise do Estresse Dentário , Teste de Materiais , Porcelana Dentária/uso terapêutico , Porcelana Dentária/química , Cerâmica/uso terapêutico , Cerâmica/química , Cimentos de Resina/uso terapêutico , Cimentos de Resina/química , Silanos/química , Água/química , Propriedades de Superfície
3.
Int J Mol Sci ; 23(22)2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36430791

RESUMO

Synthetic implants are used to treat large bone defects that are often unable to regenerate, for example those caused by osteoporosis. It is necessary that the materials used to manufacture them are biocompatible and resorbable. Polymer-ceramic composites, such as those based on poly(L-lactide) (PLLA) and calcium phosphate ceramics (Ca-P), are often used for these purposes. In this study, we attempted to investigate an innovative strategy for two-step (dual) modification of composites and their components to improve the compatibility of composite components and the adhesion between PLA and Ca-P whiskers, and to increase the mechanical strength of the composite, as well as improve osteological bioactivity and prevent bone resorption in composites intended for bone regeneration. In the first step, Ca-P whiskers were modified with a saturated fatty acid namely, lauric acid (LA), or a silane coupling agent γ-aminopropyltriethoxysilane (APTES). Then, the composite, characterized by the best mechanical properties, was modified in the second stage of the work with an active chemical compound used in medicine as a first-line drug in osteoporosis-sodium alendronate, belonging to the group of bisphosphonates (BP). As a result of the research covered in this work, the composite modified with APTES and alendronate was found to be a promising candidate for future biomedical engineering applications.


Assuntos
Osteoporose , Silanos , Humanos , Alendronato/farmacologia , Porosidade , Poliésteres/química , Osteoblastos
4.
Se Pu ; 40(10): 929-936, 2022 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-36222256

RESUMO

Pesticides are used in the agricultural production process to ensure the yield and quality of agricultural products. However, in recent years, environmental pollution issues caused by pesticide residues have sparked widespread concern in society. It is important to develop convenient and efficient approaches to detect and monitor pesticide residues. In this study, targeting benzoylurea insecticides (BUs), polyamidoamine dendrimer-functionalized silica nanocomposite with polydopamine coating (SiO2-PAMAM-PDA) was designed and successfully synthesized. First, monodisperse silica nanoparticles were prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) in mixed solution of ethanol, water and ammonia. The silane coupling agent (3-aminopropyl)triethoxysilane was then employed to introduce amino groups into the silica. Silica with the zeroth generation of polyamidoamine (PAMAM) modification (SiO2-PAMAM-G0) was obtained through Michael addition reaction of methyl acrylate. Ethylenediamine was added to polymerize with methyl acrylate using an amidation reaction to form the first-generation PAMAM (SiO2-PAMAM-G1). Finally, by polymerizing dopamine under alkaline conditions (pH=8.5), the SiO2-PAMAM-G1 was coated with PDA. Thus, the final product named SiO2-PAMAM-PDA was obtained. The composite was characterized using a transmission electron microscope (TEM) and an increase in surface roughness indicated the successful grafting of PDA coating. Dopamine structure contains abundant benzene rings and amino and hydroxyl groups. It could bind with BUs through multiple secondary interactions, such as hydrogen bond and π-π stacking interaction. Therefore, the introduction of PDA could effectively enhance the affinity of the material toward benzoylurea insecticides. The prepared nanocomposites were used as sorbents in a dispersive micro solid-phase extraction approach (D-µ-SPE). The established approach was employed to extract and enrich the BUs in water samples before high-performance liquid chromatography (HPLC) analysis. Diflubenzuron, triflumuron, hexaflumuron, and teflubenzuron were chosen as target analytes. The following was a typical D-µ-SPE procedure. The prepared adsorbents measuring 40 mg were first dispersed in an 8-mL sample solution containing 150 g/L NaCl. The dispersion was assisted by 120-s vortexing to ensure full contact between the SiO2-PAMAM-PDA and the targets. Next, the adsorbents were separated from the liquid phase by 4-min centrifugation (5000 r/min). Thereafter, the adsorbed benzoylureas were eluted using 1 mL acetonitrile as desorption solvent by 120-s vortexing. Separated by centrifugation, the eluate was dried under a mild nitrogen stream. The solid remains were redissolved in 0.1 mL of acetonitrile, filtered by filter membrane (0.22 µm), and then analyzed by HPLC. The experimental conditions in the D-µ-SPE process could have a great impact on the extraction efficiency. Experimental conditions were optimized using a single factor optimization approach to further enhance the extraction recoveries. The optimized conditions included adsorbent amount, extraction time, desorption solvent type, desorption solvent volume, desorption time, and NaCl addition amount. Under the optimal conditions, a linearity range of 10-500 µg/L and limits of detection (LODs, S/N=3) of 1.1-2.1 µg/L were obtained. The extraction recoveries and relative standard deviations (RSDs) of the four BUs were 82.8%-94.1% and 2.1%-8.0%, respectively. The established approach was compared with reported approaches targeting benzoylurea insecticides. It was discovered that this approach consumed less sample, material, organic solvent, and pretreatment time. It provided a more rapid and green choice for the determination of benzoylurea pesticides. To determine the applicability, the proposed approach was applied to analyze the four benzoylurea insecticides in three river water samples. The real water samples were pretreated using the developed approach ahead of instrumental analysis, and no benzoylurea pesticides residue was detected. Next, standard addition experiments were performed under three spiking levels, including 15, 50, and 200 µg/L. The established approach had good accuracy and feasibility with satisfactory recoveries (69.5%-99.4%) and RSDs (0.2%-9.5%).


Assuntos
Dendrímeros , Diflubenzuron , Inseticidas , Nanocompostos , Resíduos de Praguicidas , Acetonitrilas/análise , Acrilatos , Amônia/análise , Benzeno/análise , Cromatografia Líquida de Alta Pressão , Dendrímeros/análise , Diflubenzuron/análise , Dopamina/análise , Etanol/análise , Etilenodiaminas/análise , Indóis , Inseticidas/análise , Nanocompostos/análise , Nitrogênio/análise , Resíduos de Praguicidas/análise , Poliaminas , Polímeros , Silanos/análise , Dióxido de Silício/análise , Cloreto de Sódio/análise , Extração em Fase Sólida , Solventes/análise , Água/análise
5.
Int J Mol Sci ; 23(19)2022 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-36232904

RESUMO

Combinatorial therapies have garnered enormous interest from researchers in efficiently devastating malignant tumors through synergistic effects. To explore the combinatorial approach, multiple therapeutic agents are typically loaded in the delivery vehicles, controlling their release profiles and executing subsequent therapeutic purposes. Herein, we report the fabrication of core (silica)-shell (mesoporous silica nanoparticles, MSNs) architectures to deliver methylene blue (MB) and cupric doxorubicin (Dox) as model drugs for synergistic photodynamic therapy (PDT), chemotherapy, and chemodynamic therapy (CDT). MB, as the photosensitizer, is initially loaded and stabilized in the silica core for efficient singlet oxygen generation under light irradiation towards PDT. The most outside shell with imidazole silane-modified MSNs is immobilized with a chemotherapeutic agent of Dox molecules through the metal (Copper, Cu)-ligand coordination interactions, achieving the pH-sensitive release and triggering the production of intracellular hydrogen peroxide and subsequent Fenton-like reaction-assisted Cu-catalyzed free radicals for CDT. Further, the designed architectures are systematically characterized using various physicochemical characterization techniques and demonstrate the potent anti-cancer efficacy against skin melanoma. Together our results demonstrated that the MSNs-based core-shell nanoarchitectures have great potential as an effective strategy in synergistically ablating cancer through chemo-, chemodynamic, and photodynamic therapies.


Assuntos
Nanopartículas , Neoplasias , Fotoquimioterapia , Cobre/uso terapêutico , Doxorrubicina/farmacologia , Doxorrubicina/uso terapêutico , Humanos , Peróxido de Hidrogênio/uso terapêutico , Imidazóis/uso terapêutico , Ligantes , Azul de Metileno/farmacologia , Nanopartículas/química , Neoplasias/tratamento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Silanos , Dióxido de Silício/química , Oxigênio Singlete , Triazenos
6.
Int J Mol Sci ; 23(19)2022 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-36233000

RESUMO

CTP synthase (CTPS) can form filamentous structures termed cytoophidia in cells in all three domains of life. In order to study the mesoscale structure of cytoophidia, we perform fluorescence recovery after photobleaching (FRAP) and stimulated emission depletion (STED) microscopy in human cells. By using an EGFP dimeric tag as a tool to explore the physical properties of cytoophidia, we find that cytoophidia are dynamic and reticular. The reticular structure of CTPS cytoophidia may provide space for other components, such as IMPDH. In addition, we observe CTPS granules with tentacles.


Assuntos
Carbono-Nitrogênio Ligases , Citidina Trifosfato , Citidina Trifosfato/metabolismo , Humanos , Silanos
7.
Int J Mol Sci ; 23(19)2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36233325

RESUMO

In the past few years, corrosion protection of metal materials has become a global challenge, due to its great economic importance. For this reason, various methods have been developed to inhibit the corrosion process, such as surface treatment approaches, by employing corrosion inhibitors through the deposition of opportunely designed functional coatings, employed to preserve from corrosion damages metallic substrates. Recently, among these techniques and in order to avoid the toxic chromate-based pre-treatment coatings, silane-based coatings and films loaded with organic and inorganic corrosion inhibitors have been widely used in corrosion mitigation water-based surface treatment. In this study, the synthetic approach was devoted to create an embedded, hosted, waterborne, and eco-friendly matrix, obtained by use of the sol-gel technique, through the reaction of functional alkoxysilane cross-linking precursors, namely (3-glycidyloxypropyl)trimethoxysilane (GPTMS) and (3-aminopropyl)triethoxysilane (APTES), in the presence of graphene oxide (GO) intercalated with natural and non-toxic phytic acid (PA) molecules. As a matter of fact, all experimental results from FT-IR spectroscopy, UV-Vis analysis, and SEM confirmed that PA molecules were successfully decorated on GO. Furthermore, polarization measurements and a neutral salt spray test were used to evaluate the anticorrosive performance on aluminum and steel substrates, thus showing that the GO-PA nanofiller improved the barrier and corrosion protection properties of the developed functional silane-based coatings.


Assuntos
Ácido Fítico , Silanos , Alumínio/química , Cromatos , Corrosão , Grafite , Teste de Materiais , Espectroscopia de Infravermelho com Transformada de Fourier , Aço , Água
8.
Molecules ; 27(19)2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36234928

RESUMO

Fluorescence detection is currently one of the commonly used techniques worldwide. Through this work, the preparation and optical properties of an interesting composite material are discussed. It is shown that encapsulating cobalt spinel ferrite (CoFe2O4), obtained by the sol-gel autocombustion method, into poly[diphenyl-co-methyl(H)]silane matrix leads to fluoromagnetic particles (PSCo) with intriguing optical properties. Transmission electron microscopy, combined with energy-dispersive X-ray analysis, showed 500 nm large spherical structures containing a core (around 400 nm in diameter) composed of magnetic ferrite particles, surrounded by a thin layer of semiconductive fluorescent polymer. The as-obtained material exhibited ferrimagnetic properties. The FTIR spectrum confirmed that the Si-H functionality of the polysilane was preserved. UV spectroscopy combined with molecular modeling studies indicated that the magnetic core had a strong influence on the intramolecular electron transitions characteristic of the σ-conjugated polysilane. Further analysis by steady-state fluorescence spectroscopy revealed that the internal magnetic field strongly enhances the polysilane emission. This property will be further investigated in the future in order to develop new detection devices.


Assuntos
Cobalto , Silanos , Cobalto/química , Compostos Férricos , Polímeros
9.
Molecules ; 27(19)2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-36234993

RESUMO

Malachite green (MG) dye is a common environmental pollutant that threatens human health and the integrity of the Earth's ecosystem. The aim of this study was to investigate the potential biodegradation of MG dye by actinomycetes species isolated from planted soil near an industrial water effluent in Cairo, Egypt. The Streptomyces isolate St 45 was selected according to its high efficiency for laccase production. It was identified as S. exfoliatus based on phenotype and 16S rRNA molecular analysis and was deposited in the NCBI GenBank with the gene accession number OL720220. Its growth kinetics were studied during an incubation time of 144 h, during which the growth rate was 0.4232 (µ/h), the duplication time (td) was 1.64 d, and multiplication rate (MR) was 0.61 h, with an MG decolorization value of 96% after 120 h of incubation at 25 °C. Eleven physical and nutritional factors (mannitol, frying oil waste, MgSO4, NH4NO3, NH4Cl, dye concentration, pH, agitation, temperature, inoculum size, and incubation time) were screened for significance in the biodegradation of MG by S. exfoliatus using PBD. Out of the eleven factors screened in PBD, five (dye concentration, frying oil waste, MgSO4, inoculum size, and pH) were shown to be significant in the decolorization process. Central composite design (CCD) was applied to optimize the biodegradation of MG. Maximum decolorization was attained using the following optimal conditions: food oil waste, 7.5 mL/L; MgSO4, 0.35 g/L; dye concentration, 0.04 g/L; pH, 4.0; and inoculum size, 12.5%. The products from the degradation of MG by S. exfoliatus were characterized using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The results revealed the presence of several compounds, including leuco-malachite green, di(tert-butyl)(2-phenylethoxy) silane, 1,3-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, 1,4-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, 1,2-benzenedicarboxylic acid, di-n-octyl phthalate, and 1,2-benzenedicarboxylic acid, dioctyl ester. Moreover, the phytotoxicity, microbial toxicity, and cytotoxicity tests confirmed that the byproducts of MG degradation were not toxic to plants, microbes, or human cells. The results of this work implicate S. exfoliatus as a novel strain for MG biodegradation in different environments.


Assuntos
Poluentes Ambientais , Streptomyces , Biodegradação Ambiental , Corantes/química , Ecossistema , Ésteres , Humanos , Lacase , Manitol , RNA Ribossômico 16S/genética , Corantes de Rosanilina , Silanos , Solo , Streptomyces/genética , Streptomyces/metabolismo , Água
10.
Sci Rep ; 12(1): 17830, 2022 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-36284221

RESUMO

In this study, a functionalized graphene oxide catalyst (GO/f-SiO2/Co) was successfully synthesized by decorating the graphene oxide surface using the attachment of hybrid silane (silica/nitrogen) and chelation with Co (II). The catalyst has been characterized by Fourier Transform Infrared (FT-IR), powder X-ray diffraction (XRD), Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM), Raman spectra, Brunauer-Emmett-Teller (BET), and Thermal Gravimetric (TGA) analyses. The synthesized catalyst was used as an effective heterogeneous catalyst for the synthesis of triazolo[1,2-a]indazole-trione and spiro triazolo[1,2-a]indazole-tetraones derivatives under solvent-free conditions at 90 °C. The high thermal stability, corrosion resistance, and ability of the catalyst to recycle make the catalyst favorable. In addition, easy work-up procedure and short reaction time with high conversion yields (91-97%) are some benefits of the current method.


Assuntos
Silanos , Dióxido de Silício , Espectroscopia de Infravermelho com Transformada de Fourier , Indazóis , Pós , Nitrogênio
11.
PLoS One ; 17(10): e0266784, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36301845

RESUMO

The impulse-cyclone drying and the silane coupling agent (A187) modification are applied to treat wood fibers under the following conditions: 180°C, 180°C+A187, 200°C+A187, 220°C+A187 and 240°C+ A187. Then, HDPE/wood fiber composites are fabricated with a two-stage plastic extruder, and the effects of impulse-cyclone drying technique on the UV-accelerated aging properties of composites are investigated. Fourier-transform infrared spectroscopy (FTIR) reveals that the silane coupling agent chemically reacts with the hydroxyl groups on the wood fiber surfaces, the anti-UV aging properties of composites is enhanced. Mechanical test shows that during the 0-3000 h of UV aging process, the mechanical properties of samples tend to increase initially and then decrease within a period of time. After 3000 h of UV aging, the specimen 4 exhibits the least loss of mechanical properties, with flexural modulus, flexural modulus and impact strength of 65.40 Mpa, 2082.08 Mpa and 12.85 Mpa, respectively. The effects of impulse-cyclone drying technique on the UV-accelerated aging properties of composites are investigated through Spectrophotometry and Surface microstructure observation. indicates that the ΔL* and ΔE* values increase greatly at the stage of 0-1000 h aging, which though tend to stabilize after 1000 h. The degree of discoloration changes little for specimen 4,and the number of surface cracks is relatively small, which exhibits the optimal aging resistance. In conclusion, the addition of wood fibers treated by impulse-cyclone drying (220°C) and A187 modification is effective in enhancing the anti-UV aging properties of HDPE/wood fiber composites. Nevertheless, such enhancing effect turns to decline when the temperature of impulse-cyclone drying treatment is excessively high.


Assuntos
Tempestades Ciclônicas , Plásticos , Plásticos/análise , Madeira/química , Silanos/química , Polietileno/análise
12.
Dent Clin North Am ; 66(4): 603-625, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-36216449

RESUMO

Resin-bonded ceramic restorations are common treatment options. Clinical longevity of resin-bonded ceramic restorations depends on the quality and durability of the resin-ceramic bond. The type and composition of the specific ceramic determines the selection of the most effective bonding protocol. Such protocol typically includes a surface pretreatment step followed by application of a priming agent. Understanding of fundamental ceramic properties and chemical compositions enables the clinician to make proper material selection decisions for clinically successful and long-lasting restorations. Based on research accrued over the past decades, this article reviews and discusses current resin-bonding protocols to most commonly used dental ceramics.


Assuntos
Colagem Dentária , Cimentos de Resina , Cerâmica , Colagem Dentária/métodos , Porcelana Dentária , Humanos , Teste de Materiais , Silanos/química , Propriedades de Superfície
13.
Chem Commun (Camb) ; 58(90): 12604-12607, 2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-36285689

RESUMO

Despite their synthetic utility, practical methods to prepare diversely functionalized aromatic acyl silanes (benzoyl silanes) remain scarce. We herein report that cobalt complexes can successfully engage acyl silanes as weakly coordinating directing groups to catalyse the ortho C-H functionalisation of benzoyl silanes. Under Cp*Co(III) catalysis, installation of allyl or amido functionality at the 2-position of benzoyl silanes was achieved, while reaction with internal alkynes led to a desilylative annulation to afford indenone scaffolds. A Co(II)/dppp catalytic system was also investigated to achieve the acyl silane directed hydroarylative cyclisation of 1,6-enynes to access unique benzoyl silane derivatives.


Assuntos
Cobalto , Silanos , Catálise , Alcinos , Ciclização
14.
Org Lett ; 24(42): 7822-7827, 2022 10 28.
Artigo em Inglês | MEDLINE | ID: mdl-36250588

RESUMO

A nonracemic 3-silyl-3-borylhex-4-enoate reagent has been developed. Its asymmetric crotylboration of aldehydes provides Z-anti-homoallylic alcohols possessing a trisubstituted vinylsilane in high yields with excellent stereo- and enantioselectivity. Diverse decoration of vinylsilane and ester groups, as well as formation of functionalized THF rings, showcase the potential of the approach in the synthesis of polyketide natural products.


Assuntos
Aldeídos , Silanos , Estereoisomerismo , Indicadores e Reagentes
15.
J Org Chem ; 87(21): 14778-14792, 2022 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-36285601

RESUMO

Synthetically important α-oxoketene aminal intermediates can now be accessed from readily available and inexpensive carbodiimides as starting materials via the nucleophilic addition of palladium enolates derived from enol silane precursors. This operationally simple method features mild reaction conditions, including open air atmosphere, ligand-free metal catalysis, broad substrate scope, and multi-gram scalability. Select synthetic applications that take advantage of the enamine character of α-oxoketene aminals and involve C-nucleophilic additions to electrophilic systems, including an α,ß-unsaturated ester, an azo dicarboxylate, an aralkyl halide, and an aldehyde, are demonstrated.


Assuntos
Paládio , Silanos , Carbodi-Imidas , Álcoois , Catálise
16.
Anal Chim Acta ; 1229: 340174, 2022 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-36156213

RESUMO

Worldwide, the valorization of biogas, landfill gas and biomethane is gaining momentum as circular economies and energy transitions are triggered. Nevertheless, to sustainably integrate those gases into today's energy mix, their quality must be controlled regarding their major, minor and trace constituents to preserve the integrity of infrastructures wherein they are burned, transported or stored. Field gas sampling is the first and most critical step in the analytical chain to characterize the composition of such gases. A large array of gas sampling techniques is available, yet choosing the most suitable technique is complex, especially when targeting trace compounds (

Assuntos
Biocombustíveis , Compostos Orgânicos Voláteis , Gases/química , Silanos , Siloxanas , Compostos de Enxofre
17.
Exp Cell Res ; 420(1): 113337, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36087798

RESUMO

CTP synthase (CTPS), a metabolic enzyme responsible for the de novo synthesis of CTP, can form filamentous structures termed cytoophidia, which are evolutionarily conserved from bacteria to humans. Here we used Schizosaccharomyces pombe to study the cytoophidium assembly regulation by ubiquitination. We tested the CTP synthase's capacity to be post-translationally modified by ubiquitin or be affected by the ubiquitination state of the cell and showed that ubiquitination is important for the maintenance of the CTPS filamentous structure in fission yeast. We have identified proteins which are in complex with CTPS, including specific ubiquitination regulators which significantly affect CTPS filamentation, and mapped probable ubiquitination targets on CTPS. Furthermore, we discovered that a cohort of deubiquitinating enzymes is important for the regulation of cytoophidium's filamentous morphology. Our study provides a framework for the analysis of the effects that ubiquitination and deubiquitination have on the formation of cytoophidia.


Assuntos
Carbono-Nitrogênio Ligases , Schizosaccharomyces , Carbono-Nitrogênio Ligases/metabolismo , Citidina Trifosfato/metabolismo , Enzimas Desubiquitinantes/metabolismo , Humanos , Schizosaccharomyces/metabolismo , Silanos , Ubiquitinação , Ubiquitinas/metabolismo
18.
J Am Chem Soc ; 144(39): 17989-17998, 2022 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-36161865

RESUMO

Iminodirhodium reactive intermediates generated in situ from O-tosyloximes using Rh2(esp)2 in CH2Cl2 at rt were exploited for an agile trichotomy of challenging transformations: (1) remote C-H functionalizations using an exceptionally broad diversity of inorganic and organic nucleophiles including several unconventional examples, for example, ethers and acyl silanes; (2) desaturative annulation, a biomimetic 1,3-methylene C-C ring-closure with an overall loss of two hydrogens; and (3) directed desaturation for the acceptor-less, regioselective creation of γ,δ- or γ,δ,ε,ζ-olefins. Compared with typical iminyl transition-metal-mediated and 1,5-hydrogen atom-transfer (1,5-HAT) processes, iminodirhodium intermediates are largely underexplored, especially with respect to C(sp3)-H centers and, yet, have the potential to be transformative by virtue of their substrate breadth, regiocontrol, and elusive reaction modality. A substrate scope includes benzylic, allylic, propargylic, tertiary, and α-alkyloxy centers.


Assuntos
Hidrogênio , Silanos , Alcenos , Catálise , Éteres
19.
J Mater Sci Mater Med ; 33(10): 65, 2022 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-36138240

RESUMO

Chitosan coatings have shown good bioactive properties such as antibacterial and antiplatelet properties, especially on blood-contacted biomedical materials. However, as blood-contacted biomedical device, the intravascular metal stent has a burden with adverse effects on the structural integrity, such as mechanical load during implantation and substrate degradation if a biodegradable metal is used as the substrate. It is unquestionably true that the structural integrity of the coated stent is essential. The adhesion strength between the coating and the substrate positively affects it. Silane and polydopamine (PDA) interstitial layers have been investigated to improve the corrosion resistance, biosafety and adhesion strength. This work addressed this challenge by using PDA as an intermediate and glutaraldehyde as a linking agent to establish a strong link between the polymer coating and the intermediate coating. Compared with PDA-only and glutaraldehyde-linked silane layer, the novel coating displayed a notable increase in adhesion. When compared with the bare Ni-free stainless steel, the performance of the novel coating was not significantly different. This novel chitosan film on the glutaraldehyde linked-PDA interface can be applied to various metallic substrates where synergic bioactive and anticorrosive effects of PDA interstitial coating and chitosan are needed. Graphical abstract.


Assuntos
Quitosana , Antibacterianos/química , Quitosana/química , Materiais Revestidos Biocompatíveis/química , Glutaral , Indóis , Polímeros/química , Silanos , Aço Inoxidável/química
20.
J Org Chem ; 87(19): 13073-13088, 2022 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-36163013

RESUMO

A Co(III)-catalyzed redox-neutral [4 + 2] annulation of N-chlorobenzamides/acrylamides with substituted alkenes at ambient temperature is demonstrated. Using this protocol, pharmaceutically important 3,4-dihydroisoquinolinone derivatives were synthesized in good yields. Intriguingly, the synthetically useful functional group of allylic coupling partners such as sulfonyl, carbonate, acetate, phosphate, amide, nitrile, and silane were retained in the final cyclized product. The present annulation reaction was compatible with various substituted benzamides and allylic coupling partners. To support the proposed reaction mechanism, competition experiments, deuterium labeling studies, and kinetic isotope effect studies were performed.


Assuntos
Alcenos , Cobalto , Acetatos , Acrilamidas , Amidas , Benzamidas , Catálise , Deutério , Nitrilas , Fosfatos , Silanos , Estereoisomerismo
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