RESUMO
Lignin, a vital renewable biopolymer, serves as the Earth's primary source of aromatics and carbon. Its depolymerization presents significant potential for producing phenolic fine chemicals. This study assesses promoted Ni-based bimetallic catalysts (Ni-Co/C and Ni-Cu/C) supported on activated carbon in isopropanol for lignin depolymerization, compared to monometallic counterparts. BET, SEM, EDX, and XPS analyses highlight their physicochemical properties and promotional effects, enhancing hydrogenolysis activity and hydrogen transformation. Reaction parameter exploration elucidates the influence on lignin depolymerization, with cobalt and copper as promoters notably increasing conversion and monomer yield. Ni-Co/C exhibits the highest lignin conversion (94.2%) and maximum monomer yield (53.1 wt%) under specified conditions, with lower activation energy (36.1 kJ/mol) and higher turnover frequency (31.6 h-1) compared to Ni/C. FT-IR, GPC, GC-FID, and GC-MS analyses confirm effective depolymerization, identifying 20 monomer products. Proposed reaction mechanisms underscore the potential of Ni-based bimetallic catalysts for lignin valorization, offering insights into developing efficient catalytic systems for lignin hydrogenolysis. This research enhances understanding and facilitates the development of selective catalytic processes for lignin valorization.
Assuntos
2-Propanol , Cobalto , Lignina , Níquel , Fenóis , Solventes , Lignina/química , Catálise , Níquel/química , Cobalto/química , Fenóis/química , Solventes/química , 2-Propanol/química , Cobre/química , PolimerizaçãoRESUMO
Membrane-based pervaporation (PV) for organic solvent dehydration is of great significance in the chemical and petrochemical industries. In this work, high-aluminum ZSM-5 zeolite membranes were synthesized by a fluoride-assisted secondary growth on α-alumina tubular supports using mordenite framework inverted (MFI) nanoseeds (~110 nm) and a template-free synthesis solution with a low Si/Al ratio of 10. Characterization by XRD, EDX, and SEM revealed that the prepared membrane was a pure-phase ZSM-5 zeolite membrane with a Si/Al ratio of 3.8 and a thickness of 2.8 µm. Subsequently, two categories of PV performance parameters (i.e., flux versus separation factor and permeance versus selectivity) were used to systematically examine the effects of operating conditions on the PV dehydration performance of different organic solvents (methanol, ethanol, n-propanol, and isopropanol), and their PV mechanisms were explored. Employing permeance and selectivity effectively disentangles the influence of operating conditions on PV performance, thereby elucidating the inherent contribution of membranes to separation performance. The results show that the mass transfer during PV dehydration of organic solvents was mainly dominated by the adsorption-diffusion mechanism. Furthermore, the diffusion of highly polar water and methanol molecules within membrane pores had a strong mutual slowing-down effect, resulting in significantly lower permeance than other binary systems. However, the mass transfer process for water/low-polar organic solvent (ethanol, n-propanol, and isopropanol) mixtures was mainly controlled by competitive adsorption caused by affinity differences. In addition, the high-aluminum ZSM-5 zeolite membrane exhibited superior PV dehydration performance for water/isopropanol mixtures.
Assuntos
Membranas Artificiais , Solventes , Zeolitas , Zeolitas/química , Solventes/química , Água/química , 2-Propanol/química , Alumínio/química , Etanol/químicaRESUMO
OBJECTIVES: To investigate the impact of a centrifugation method on the surface characteristics, flexural properties, and cytotoxicity of an additively manufactured denture base polymer. METHODS: The tested specimens were prepared by digital light processing (DLP). A centrifugation method (CENT) was used to remove the residual uncured resin. In addition, the specimens were post-processed with different post-rinsing solutions: isopropanol (IPA), ethanol (EtOH), and tripropylene glycol monomethyl ether (TPM), respectively. A commercial heat-polymerized polymethyl methacrylate was used as a reference (REF). First, the values of surface topography, arithmetical mean height (Sa), and root mean square height (Sq) were measured. Next, flexural strength (FS) and modulus were evaluated. Finally, cytotoxicity was assessed using an extract test. The data were statistically analyzed using a one-way analysis of variance, followed by Tukey's multiple comparison test for post-hoc analysis. RESULTS: The Sa value in the CENT group was lower than in the IPA, EtOH, TPM, and REF groups (p < 0.001). Moreover, the CENT group had lower Sq values than other groups (p < 0.001). The centrifugation method showed a higher FS value (80.92 ± 8.65 MPa) than the EtOH (61.71 ± 12.25 MPa, p < 0.001) and TPM (67.01 ± 9.751 MPa, p = 0.027), while affecting IPA (72.26 ± 8.80 MPa, p = 0.268) and REF (71.39 ± 10.44 MPa, p = 0.231). Also, the centrifugation method showed no evident cytotoxic effects. CONCLUSIONS: The surfaces treated with a centrifugation method were relatively smooth. Simultaneously, the flexural strength of denture base polymers was enhanced through centrifugation. Finally, no evident cytotoxic effects could be observed from different post-processing procedures. CLINICAL SIGNIFICANCE: The centrifugation method could optimize surface quality and flexural strength of DLP-printed denture base polymers without compromising cytocompatibility, offering an alternative to conventional rinsing post-processing.
Assuntos
Centrifugação , Bases de Dentadura , Teste de Materiais , Polímeros , Polimetil Metacrilato , Impressão Tridimensional , Propriedades de Superfície , Polimetil Metacrilato/química , Polímeros/química , Resistência à Flexão , Animais , Camundongos , Etanol , 2-Propanol/química , Materiais Dentários/química , Módulo de Elasticidade , HumanosRESUMO
High-quality DNA is an important guarantee to start downstream experiments in many biological and medical research areas. Magnetic particle-based DNA extraction methods from blood mainly depend on electrostatic adsorption in a low-pH environment. However, the strong acidic environment can influence the DNA stability. Herein, a polydopamine-functionalized magnetic particle (PDA@Fe3O4)-based protocol was developed for DNA extraction from whole blood samples. In the protocol, Mg2+ and Ca2+ were utilized to bridge the adsorption of DNA by PDA@Fe3O4 via the metal-mediated coordination. Isopropanol was found to efficiently promote DNA adsorption by triggering the change of the conformation of DNA from B-form to more compact A-form. In 50 % isopropanol solution, the DNA adsorption efficiency was nearly 100 % in the presence of 0.5 mM Ca2+ or 1.5 mM Mg2+. The role of metal ions and isopropanol in DNA adsorption was explored. The protocol averts the strong acidic environment and PCR inhibitors, such as high concentrations of salt or polyethylene glycol. It demonstrates superiority in DNA yield (59.13 ± 3.63 ng µL-1) over the commercial kit (27.33 ± 4.98 ng µL-1) and phenol-chloroform methods (37.90 ± 0.47 ng µL-1). In addition, to simplify the operastion, an automated nucleic acid extraction device was designed and fabricated to extract whole genomic DNA from blood. The feasibility of the device was verified by extracting DNA from cattle and pig blood samples. The extracted DNA was successfully applied to discriminate the beef authenticity by a duplex PCR system. The results demonstrate that the DNA extraction protocol and the automated device have great potential in blood samples.
Assuntos
2-Propanol , DNA , Indóis , Polímeros , Polímeros/química , 2-Propanol/química , DNA/química , DNA/isolamento & purificação , DNA/sangue , Indóis/química , Adsorção , Magnésio/química , Animais , Cálcio/química , Cálcio/sangue , Bovinos , Nanopartículas de Magnetita/químicaRESUMO
This study evaluates the repurposing of expired isopropanol (IPA) COVID-19 disinfectant (64% w/w) to pretreat algal biomass for enhancing methane (CH4) yield. The impact of harvesting methods (centrifugation and polymer flocculation) and microwave pretreatment on CH4 production from Scenedesmus sp. microalgal biomass were also investigated. Results show minimal impact of harvesting methods on the CH4 yield, with wet centrifuged and polymer-harvested biomass exhibiting comparable and low CH4 production at 66 and 74 L/kgvolatile solid, respectively. However, microalgae drying significantly increased CH4 yield compared to wet biomass, attributed to cell shrinkage and enhanced digestibility. Consequently, microwave and IPA pretreatment significantly enhanced CH4 production when applied to dried microalgae, yielding a 135% and 212% increase, respectively, compared to non-pretreated wet biomass. These findings underscore the advantage of using dried Scenedesmus sp. over wet biomass and highlight the synergistic effect of combining oven drying with IPA treatment to boost CH4 production whilst reducing COVID-19 waste.
Assuntos
Biomassa , COVID-19 , Desinfetantes , Metano , Scenedesmus , Scenedesmus/efeitos dos fármacos , Desinfetantes/farmacologia , Metano/metabolismo , COVID-19/prevenção & controle , Microalgas/efeitos dos fármacos , Polímeros/química , Polímeros/farmacologia , 2-Propanol/farmacologia , 2-Propanol/química , SARS-CoV-2/efeitos dos fármacosRESUMO
We report a study on the hydrogen bonding mechanisms of three aliphatic alcohols (2-propanol, methanol, and ethanol) and one diol (ethylene glycol) in water solution using a time-domain ellipsometer in the THz region. The dielectric response of the pure liquids is nicely modeled by the generalized Debye-Lorentz equation. For binary mixtures, we analyze the data using a modified effective Debye model, which considers H-bond rupture and reformation dynamics and the motion of the alkyl chains and of the OH groups. We focus on the properties of the water-rich region, finding anomalous behavior in the absorption properties at very low solute molar concentrations. These results, first observed in the THz region, are in line with previous findings from different experiments and can be explained by taking into account the amphiphilic nature of the alcohol molecules.
Assuntos
Álcoois , Ligação de Hidrogênio , Água , Água/química , Álcoois/química , Espectroscopia Terahertz/métodos , Etanol/química , 2-Propanol/químicaRESUMO
Nucleophilic moieties in polysaccharides (PS) with distinct higher reactivity compared with the hydroxy group are interesting for sustainable applications in chemistry, medicine, and pharmacy. An efficient heterogeneous method for the formation of such nucleophilic PS is described. Employing alcohols as slurry medium, protonated carboxymethyl (CM) PS and hydrazine hydrate are allowed to react at elevated temperatures. The CM derivatives of starch and pullulan can be transformed almost quantitatively to the corresponding hydrazides. The reaction is less efficient for CM dextrans and CM xylans. As slurry media, 2-propanol and ethanol were probed, and the results are compared with a homogeneous procedure performed in water. Overall, the heterogeneous procedure is superior compared with the homogeneous route. 2-Propanol is the best slurry medium investigated yielding PS hydrazides with the highest nitrogen content.
Assuntos
Hidrazinas , Polissacarídeos , Hidrazinas/química , Polissacarídeos/química , Polissacarídeos/síntese química , Glucanos/química , Glucanos/síntese química , Amido/química , Amido/análogos & derivados , Amido/síntese química , 2-Propanol/química , Dextranos/química , Dextranos/síntese química , Etanol/química , Xilanos/químicaRESUMO
High-performance liquid chromatography-based enantioseparation of newly prepared azole analogs of monoterpene lactones and amides was studied. Effects of additives and mobile phase composition were evaluated both in normal and polar organic modes. Applying amylose tris-(3,5-dimethylphenylcarbamate) selector in normal and polar organic modes acid and base additives were found to affect the peak profiles, without significantly influencing the enantiorecognition ability of the studied selector. In most cases, differences observed in retention times and enantioselectivities were lower than 10 and 20 % under normal phase and polar organic conditions, respectively. Under normal phase conditions decreased retention was observed for all the studied analytes with increased eluent polarity. Interestingly, enantioselectivity was only slightly (<10 %) influenced by the variation in the n-hexane/2-propanol ratio between 80/20 and 20/80 v/v. In polar organic mode, five different neat solvents (acetonitrile, methanol, ethanol, 1-propanol, and 2-propanol) were tested, and the best results were obtained with acetonitrile and ethanol in the case of Lux Amylose-1 column with enantioresolutions most often above 2. Based on results obtained with amylose and cellulose-based columns the amylose tris-(3,5-dimethylphenylcarbamate) selector is found to offer a superior performance both in normal and polar organic modes. When evaluating the possible effects of the selector immobilization, no striking differences were found in the normal phase. Usually, enantioselectivities and resolutions were higher (10-20 %), while retention factors of the first peaks were lower (20-30 %), on the coated-type column. In contrast, in polar organic mode, the retention characteristics and enantiorecognition ability of the coated and immobilized selectors were heavily affected by the nature of the polar solvent. Special attention has been paid to the history-dependent behavior of polysaccharide-based selectors. A confidence interval-based evaluation is suggested to help comparison of the histereticity observed in different systems. Several examples are shown to confirm that the recently discovered hysteresis is a common characteristic of polysaccharide-based selectors.
Assuntos
Amidas , Amilose , Cromatografia Líquida de Alta Pressão/métodos , Amilose/química , Lactonas , 2-Propanol/química , Monoterpenos , Polissacarídeos/química , Fenilcarbamatos/química , Solventes/química , Etanol , Acetonitrilas , EstereoisomerismoRESUMO
The solubility of thiamine nitrate in {(methanol, acetone, isopropanol) + water} solvents will provide essential support for crystallization design and further theoretical studies. In this study, the solubility was experimentally measured over temperatures ranging from 278.15 to 313.15 K under atmospheric pressure using a dynamic method. The solubility increased with increasing temperature at a constant solvent composition. The dissolving capacity of thiamine nitrate in the three binary solvent mixtures at constant temperature in the low ratio of water ranked as water + methanol > water + acetone > water + isopropanol generally. Interestingly, in the high ratio of water systems, especially when the molar concentration of water was greater than 0.6, the dissolving capacity ranked as water + acetone > water + methanol > water + isopropanol. Additionally, the modified Apelblat equation, λh equation, van't Hoff equation and NRTL model were used to correlate the solubility data in binary mixtures. It turned out that all the selected thermodynamic models could give satisfactory results. Furthermore, the thermodynamic properties of the dissolution process of thiamine nitrate were also calculated based on the modified van't Hoff equation. The results indicate that the dissolution process of the thiamine nitrate in the selected solvents is all endothermic.
Assuntos
Metanol , Nitratos , Solventes/química , Metanol/química , Solubilidade , 2-Propanol/química , Acetona , Tiamina , Termodinâmica , Água/química , TemperaturaRESUMO
Chiral stationary phases (CSPs) with coated amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) selector have long been recognized for their excellent chiral recognition ability in liquid chromatography. The conformational versatility behind this feature is the source of their known hysteretic behavior, which has been previously observed in polar organic (PO) mode eluents containing 2-propanol (IPA). Mixtures of IPA and acetonitrile (MeCN), a typical PO mode eluent system, have not been examined in this aspect yet, even though hysteresis is promising for finding unique unexplored enantioselectivities. Not only was the hysteresis detectable on ADMPC using mixtures of IPA and MeCN, but it was the typical behavior in a diverse set of test compounds. The difference in the retention time of the same analyte under conditions which only differed in the eluent history on the column can go up to 20-fold. The assumed hindered conformational changes of the selector were reflected in retention drift at certain eluent compositions. On the two sides of the transitions, distinct, useful states of the selector were detected. A series of IPA - MeCN compositions with defined pretreatment was selected and recommended as an extension of the preliminary, first choice method screening set that used only alcohols. The incorporation of a solvent possessing substantially different characteristics enhances the potential in practical applications, while keeping the technical simplicity. Stability and robustness of the additional states of the CSP were characterized. The examined columns of different brands shared the observed behavior. Kinetic stability of a column state is adequate for successful application. The evaluated states of ADMPC provide multiple enantiorecognition potential by using mixtures of IPA and MeCN also considering the pretreatment of the column. Unprecedented double and triple elution order reversals along the composition range supported the versatility of the available states. Our findings further enhance the usefulness of ADMPC-containing CSPs. We provide instructions for the application of the widespread chiral selector in common eluent mixtures to avoid pitfalls regarding reproducibility and robustness.
Assuntos
2-Propanol , Fenilcarbamatos , 2-Propanol/química , Reprodutibilidade dos Testes , Solventes/química , Fenilcarbamatos/química , Amilose/química , Acetonitrilas , Estereoisomerismo , Cromatografia Líquida de Alta Pressão/métodosRESUMO
Deuterium (2H, D) is a stable isotope of hydrogen (1H). Deuterium-incorporated (labelled) compounds are widely utilized in various scientific fields such as mechanistic studies of organic reactions, elucidation of drug metabolism, application as tracers for microanalysis. Recently, development of heavy drugs and molecular imaging using techniques such as neutron scattering and Raman spectroscopy are spotlighted. We have developed various deuterium-incorporated compounds using D2O as an inexpensive deuterium source to construct novel functional materials. The use of platinum group metals on carbon as catalysts could result in the multi-deuteration of compounds in the mixed solvents of 2-propanol and D2O, and site-selectively deuterated compounds can be synthesized by organocatalytic methods. In this review, the latter deuteration methods using organocatalysts and their applications are summarized. Terminal alkynes smoothly underwent deuterium incorporation by using triethylamine as an organic base or a solid resin possessing the tertiary amine moiety in the same molecule to give mono-deuterated alkynes. These compounds were partially reduced over our prepared specific palladium catalyst under atmospheric D2 gas to produce tri-deuterated alkenes. Achiral or chiral di-deuterated ß-nitro alcohols were also prepared by the organic-base-catalyzed deuteration of nitromethane, followed by nitroaldol reactions in a one pot manner. The mono-deuteration of aromatic aldehyde could be effectively catalyzed by N-heterocyclic carbene. Furthermore, the α-deuteration of aliphatic aldehydes using a basic resin catalyst and the subsequent Knoevenagel condensation with malononitrile could provide γ-deuterium-incorporated α,ß-unsaturated nitrile derivatives. The deuterated compounds thus obtained can be important synthetic precursors to construct the deuterium-incorporated target functional materials.
Assuntos
Alcenos/síntese química , Alcinos/química , Alcinos/síntese química , Química Orgânica/métodos , Deutério/química , Desenvolvimento de Medicamentos/métodos , Etilaminas/química , 2-Propanol/química , Aminas/síntese química , Carbono/química , Catálise , Gases , Metano/análogos & derivados , Metano/química , Imagem Molecular/métodos , Nitrilas/síntese química , Nitrilas/química , Nitroparafinas/química , Paládio/química , Platina/química , SolventesRESUMO
OBJECTIVE: The main objective of this paper is to analyse and attempt to understand the nature of rheological changes observed and the dynamics of Carbopol NF 980 hydroalcoholic gels neutralized specifically by triethanol amine (TEA), both as a function of time and alcohol type to probe time stabilities and ageing effects in such carbopol gel systems. The rheological changes and dynamics of 3 carbopol gel systems were observed; the gels included a water-based, ethanol-based, and isopropyl alcohol-based gel. It is hoped that this study shall shed light on the dynamical nature and the microstructural evolution of such networked gel systems, which were maintained under closed isothermal conditions and left completely unperturbed. The experimental results can provide the information necessary to understand and proposes plausible mechanisms guiding this dynamical behaviour in hydroalcoholic carbopol gels. METHODS: A TA instrument mechanical rheometer was used to measure the viscosity and storage and loss modulus, and a pH meter was utilized to determine the changes in each sample over the period. RESULTS: Studying the differences in the gel structures upon initial preparation illustrated that the ethanol and isopropyl alcohol (IPA) gels differed from the water-based gel in terms of viscosity, G', and Gâ³, with the IPA gel displaying the lowest viscosity and moduli values across all shear rates. All the three gel systems exhibited strong shear thinning characteristics and were reminiscent of yield stress type found in colloidal gels. The water-based gel compared to the hydroalcoholic gels was strongly G' dominated, with the magnitude of the difference between G' and Gâ³ observed to be much higher. This reflects that initial formation of the water-based gel structure possesses a much more rigid structure with a high elastic modulus component dominating. This also suggests that the water-based gel structure displayed stronger interactions between the carbopol particles when compared to those of the hydroalcoholic gels. Over the 30-day period, it was observed that the ethanol and water-based gels did not reveal any appreciable viscosity changes, with only an approximate 12% and 7% change from day 1 to 30, respectively. It was observed that the IPA systems' viscosity drastically increased over the period, with an approximately 77% change from day 1 to 30. The water and ethanol-based gels also exhibited very similar rheological behaviour over the entire time period with G' dominating Gâ³. The Gâ³ values of the water and ethanol-based gels decreased slightly at the end of day 30 by 10% and 16%, respectively, while the G' values for each sample remained essentially unchanged, increasing only 0.06% for the water-based gel, and increasing 1.4% for the ethanol-based gel. This further confirms the relatively stable gel structures attained. For the isopropyl gel system, the storage modulus of the system exhibited an average percent increase of approximately 16% from day 1 to day 30, but interestingly the loss modulus varied the least amongst all the gel systems, with only a 3% increase. The increase in G' reflects upon the evolution of a more rigid structure by day 30 for the IPA gel. This observation is clearly consistent with the corresponding increase in viscosity observed in the IPA gel. None of the gels tested displayed a consistent pH over the period. The pH of the hydroalcoholic gels was higher than that of the water-based gel for a majority of the period. The greatest fluctuations in pH were observed for the water and IPA gels, even though the water-based gel had one of the most stable rheological profiles out of the samples tested. The water, ethanol, and IPA gels' pH increased approximately 25%, 6%, and 5%, respectively, from day 1 to day 30. CONCLUSION: The rheological and pH study of the 3 hand sanitizer systems over a 30-day period allowed for rational insights into the plausible reasons responsible for driving the observed rheological changes in these unperturbed systems. For the water-based gel, we hypothesize that the changes observed are due to physical ageing, where the gel structure has evolved over time to eventually progress towards a more stabilized framework structure. The pH of the gel upon formation was on the lower side. Such a lower pH influences the formation of a gel, which is comparatively less swollen and occupies a slightly lesser volume, and thereby points to a much less compacted gel network structure or alternatively, a more fluid structure. If the particles moved around more, the system was not initially in a state of low energy, causing increased particle movement, and in turn, physical ageing. This could be responsible for the development of a physically altered structure over time. The gel structure dynamically attempts to minimize its free energy by becoming more rigid, which has been observed as being manifested in the decrease of both the viscosity and the Gâ³. For the hydroalcoholic gels, we conjecture that ageing observed was a result of chemical ageing, and the alcohol type employed in the preparation is primarily responsible for exhibiting this effect. The polarities of ethyl alcohol and isopropyl alcohol are key to the stabilization of such resultant network structures which get formed because of neutralization. It has been observed in previous studies that with decreasing polarity, there was an increase in the neutralization needed to obtain the development of a structure half as well developed as the final resultant structure. Isopropyl alcohol is a much less polar solvent compared to ethanol and water, and therefore required higher levels of TEA as the base to neutralize the system. We conjecture that the charged TEA cationic species had a greater propensity to get exchanged with bulk solution in the vicinity of the polymer into the bulk solution, and that the pH fluctuation observed indicated a kinetic exchange process over time, causing the viscosity and moduli profiles to increase along with the pH. At this time though, further investigations need to be carried out to truly understand the underlying instability, and thus dynamics for gel systems of this type.
OBJECTIF: L'objectif principal de cet article est d'analyser et de tenter de comprendre la nature des changements rhéologiques observés et la dynamique des gels hydroalcooliques Carbopol NF 980 neutralisés spécifiquement par l'amine triéthanol (TEA), à la fois en fonction du temps et du type d'alcool pour sonder les stabilités temporelles et les effets du vieillissement dans de tels systèmes de gel carbopol. Les changements rhéologiques et la dynamique de 3 systèmes de gel de carbopol ont été observés ; les gels comprenaient un gel à base d'eau, d'éthanol et d'alcool isopropylique. On espère que cette étude éclairera la nature dynamique et l'évolution microstructurale de ces systèmes de gel en réseau, qui ont été maintenus dans des conditions isothermes fermées et laissés complètement imperturbables. Les résultats expérimentaux peuvent fournir les informations nécessaires pour comprendre et proposer des mécanismes plausibles guidant ce comportement dynamique dans les gels hydroalcooliques de carbopol. MÉTHODE: Un rhéomètre TA mécanique a été utilisé pour mesurer la viscosité, le module de stockage et de perte, et un pH-mètre a été utilisé pour déterminer les changements dans chaque échantillon au cours de la période. RÉSULTATS: L'étude des différences dans les structures du gel lors de la préparation initiale a montré que les gels d'éthanol et d'alcool isopropylique (IPA) différaient du gel à base d'eau en termes de viscosité, G' et G'' le gel IPA affichant les valeurs de viscosité et de modules les plus faibles pour tous les taux de cisaillement. Les trois systèmes de gel présentaient de fortes caractéristiques d'amincissement par cisaillement et rappelaient le type de contrainte d'élasticité que l'on trouve dans les gels colloïdaux. Le gel à base d'eau par rapport aux gels hydroalcooliques était fortement dominé par G', l'ampleur de la différence entre G' et G'' présentant une importance beaucoup plus élevée. Cela reflète le fait que la formation initiale de la structure de gel à base d'eau possède une structure beaucoup plus rigide avec un composant de module élastique élevé dominant. Cela suggère également que la structure du gel à base d'eau présentait des interactions plus fortes entre les particules de carbopol par rapport à celles des gels hydroalcooliques. Au cours de la période de 30 jours, il a été observé que l'éthanol et les gels à base d'eau n'ont révélé aucun changement de viscosité appréciable, avec seulement un changement approximatif de 12% et 7% du jour 1 au jour 30, respectivement. Il a été observé que la viscosité des systèmes IPA a considérablement augmenté au cours de la période, avec un changement d'environ 77% du jour 1 au jour 30. Les gels à base d'eau et d'éthanol ont également montré un comportement rhéologique très similaire sur toute la période, G' dominant G''. Les valeurs G'' des gels à base d'eau et d'éthanol ont légèrement diminué à la fin de la journée 30 de 10% et 16%, respectivement, tandis que les valeurs G' pour chaque échantillon sont restées essentiellement inchangées, n'augmentant que de 0,06% pour le gel à base d'eau et augmentant de 1,4% pour le gel à base d'éthanol. Cela confirme en outre les structures de gel relativement stables atteintes. Pour le système de gel isopropylique, le module de stockage du système a montré une augmentation moyenne d'environ 16% du jour 1 au jour 30, mais il est intéressant de noter que le module de perte variait le moins parmi tous les systèmes de gel, avec seulement une augmentation de 3%. L'augmentation de G' reflète l'évolution d'une structure plus rigide au jour 30 pour le gel IPA. Cette observation est clairement cohérente avec l'augmentation correspondante de la viscosité observée dans le gel IPA. Aucun des gels testés n'a montré un pH constant sur la période. Le pH des gels hydroalcooliques était supérieur à celui du gel à base d'eau pendant la majeure partie de la période. Les plus grandes fluctuations de pH ont été observées pour les gels d'eau et d'IPA, même si le gel à base d'eau avait l'un des profils rhéologiques les plus stables parmi les échantillons testés. Le pH de l'eau, de l'éthanol et des gels IPA a augmenté d'environ 25%, 6% et 5%, respectivement, du jour 1 au jour 30. CONCLUSION: L'étude rhéologique et pH des 3 systèmes de désinfectant pour les mains sur une période de 30 jours a permis d'obtenir des informations rationnelles sur les raisons plausibles responsables des changements rhéologiques observés dans ces systèmes non perturbés. Pour le gel à base d'eau, nous émettons l'hypothèse que les changements observés sont dus au vieillissement physique, où la structure du gel a évolué au fil du temps pour éventuellement progresser vers une structure plus stabilisée. Le pH du gel lors de la formation était dans la partie inférieure. Un pH aussi bas influence la formation d'un gel, qui est comparativement moins gonflé et occupe un volume légèrement inférieur, et indique ainsi une structure de réseau de gel beaucoup moins compactée ou autrement dit, une structure plus fluide. Si les particules se déplaçaient davantage, le système n'était pas initialement dans un état de faible énergie, ce qui entraînait une augmentation du mouvement des particules et, à son tour, un vieillissement physique. Cela pourrait être responsable du développement d'une structure physiquement modifiée au fil du temps. La structure du gel tente dynamiquement de minimiser son énergie libre en devenant plus rigide, ce qui a été observé comme se manifestant par la diminution de la viscosité et du G'' Pour les gels hydroalcooliques, nous pensons que le vieillissement observé était le résultat d'un vieillissement chimique, et le type d'alcool utilisé dans la préparation est principalement responsable de cet effet. Les polarités de l'alcool éthylique et de l'alcool isopropylique sont essentielles à la stabilisation de ces structures de réseau résultantes qui se forment en raison de la neutralisation. Il a été observé dans des études antérieures qu'avec la diminution de la polarité, il y avait une augmentation de la neutralisation nécessaire pour obtenir le développement d'une structure à moitié aussi bien développée que la structure résultante finale. L'alcool isopropylique est un solvant beaucoup moins polaire que l'éthanol et l'eau, et nécessitait donc des niveaux plus élevés de TEA comme base pour neutraliser le système. Nous pensons que les espèces cationiques TEA chargées avaient une plus grande propension à être échangées avec une solution en vrac à proximité du polymère, dans la solution en vrac, et que la fluctuation du pH observée indiquait un processus d'échange cinétique au fil du temps, entraînant une augmentation des profils de viscosité et de modules avec le pH. À l'heure actuelle, cependant, des recherches supplémentaires doivent être menées pour vraiment comprendre l'instabilité sous-jacente, et donc la dynamique des systèmes de gel de ce type.
Assuntos
2-Propanol/química , Resinas Acrílicas/química , Etanol/química , Hidrogéis/química , Reologia , Água/químicaRESUMO
Strong light localization inside the nanoscale gaps provides remarkable opportunities for creation of various medical and biosensing platforms stimulating an active search for inexpensive and easily scalable fabrication at a sub-100 nm resolution. In this paper, self-organized laser-induced periodic surface structures (LIPSSs) with the shortest ever reported periodicity of 70 ± 10 nm were directly imprinted on the crystalline Si wafer upon its direct femtosecond-laser ablation in isopropanol. Appearance of such a nanoscale morphology was explained by the formation of a periodic topography on the surface of photoexcited Si driven by interference phenomena as well as subsequent down-scaling of the imprinted grating period via Rayleigh-Taylor hydrodynamic instability. The produced deep subwavelength LIPSSs demonstrate strong anisotropic anti-reflection performance, ensuring efficient delivery of the incident far-field radiation to the electromagnetic "hot spots" localized in the Si nanogaps. This allows realization of various optical biosensing platforms operating via strong interactions of quantum emitters with nanoscale light fields. The demonstrated 80-fold enhancement of spontaneous emission from the attached nanolayer of organic dye molecules and in situ optical tracing of catalytic molecular transformations substantiate bare and metal-capped deep subwavelength Si LIPSSs as a promising inexpensive multifunctional biosensing platform.
Assuntos
Técnicas Biossensoriais , Lasers , Silício/química , 2-Propanol/química , Hidrodinâmica , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
The study is aimed at establishing the optimal parameters for RNA purification of pooled specimens, in SARS-CoV-2 assay. This research work evaluates the difference of extracted RNA purity of pooled samples with and without treatment with isopropyl alcohol and its effect on real-time RT-PCR. As per the protocol of the Indian Council of Medical Research (ICMR), 5 sample pools were analysed using qRT-PCR. A total of 100 pooled samples were selected for the study by mixing 50 µL of one COVID-19 positive nasopharyngeal/oropharyngeal (NP/OP) specimen and 50 µL each of 4 known negative specimens. Pool RNA was extracted using the column-based method, and 1 set of pooled extracted RNA was tested as such, while RNA of the second set was treated additionally with chilled isopropyl alcohol (modified protocol). Further, the purity of extracted RNA in both the groups was checked using Microvolume Spectrophotometers (Nanodrop) followed by RT-PCR targeting E-gene and RNaseP target. The results showed that the purity index of extracted RNA of untreated pooled specimens was inferior to isopropyl alcohol-treated templates, which was observed to be 85% sensitivity and 100% specificity. The average Cq (E gene) in the unpurified and purified pool RNA group was 34.66 and 31.48, respectively. The nanodrop data suggested that purified RNA concentration was significantly increased with an average value of 24.73 ± 1.49 ng/uL, which might be the reason for high sensitivity and specificity. Thus, this group testing of SARS-CoV-2 cases using pools of 5 individual samples would be the best alternative for saving molecular reagents, personnel time, and can increase the overall testing capacity. However, purity of RNA is one of the important determinants to procure unfailing results, thus, this additional purification step must be included in the protocol after RNA has been extracted using commercially available kit before performing qRT-PCR.
Assuntos
COVID-19/diagnóstico , Proteínas do Envelope de Coronavírus/genética , RNA Viral/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real/métodos , SARS-CoV-2/genética , 2-Propanol/química , Biomarcadores/análise , COVID-19/virologia , Primers do DNA/síntese química , Primers do DNA/genética , Humanos , Nasofaringe/virologia , Orofaringe/virologia , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real/economia , Reação em Cadeia da Polimerase em Tempo Real/normas , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
This article studies the solubility, Hansen solubility parameters (HSPs), and thermodynamic behavior of a naturally-derived bioactive thymoquinone (TQ) in different binary combinations of isopropanol (IPA) and water (H2O). The mole fraction solubilities (x3) of TQ in various (IPA + H2O) compositions are measured at 298.2-318.2 K and 0.1 MPa. The HSPs of TQ, neat IPA, neat H2O, and binary (IPA + H2O) compositions free of TQ are also determined. The x3 data of TQ are regressed by van't Hoff, Apelblat, Yalkowsky-Roseman, Buchowski-Ksiazczak λh, Jouyban-Acree, and Jouyban-Acree-van't Hoff models. The maximum and minimum x3 values of TQ are recorded in neat IPA (7.63 × 10-2 at 318.2 K) and neat H2O (8.25 × 10-5 at 298.2 K), respectively. The solubility of TQ is recorded as increasing with the rise in temperature and IPA mass fraction in all (IPA + H2O) mixtures, including pure IPA and pure H2O. The HSP of TQ is similar to that of pure IPA, suggesting the great potential of IPA in TQ solubilization. The maximum molecular solute-solvent interactions are found in TQ-IPA compared to TQ-H2O. A thermodynamic study indicates an endothermic and entropy-driven dissolution of TQ in all (IPA + H2O) mixtures, including pure IPA and pure H2O.
Assuntos
2-Propanol/química , Benzoquinonas/química , Química Farmacêutica/métodos , Água/química , Técnicas de Química Analítica , Desenho de Fármacos , Análise de Regressão , Reprodutibilidade dos Testes , Solubilidade , Solventes , Temperatura , TermodinâmicaRESUMO
The electrostatic interactions between chiral solutes and polysaccharide (PS)-based chiral selectors are the key to achieving chiral recognition; however, PS-based sorbents, derivatized of phenyl moieties, can exhibit considerably non-polar characteristics, and they are also useful for the separation of enantiomers in the reversed-phase mode. In this study, an immobilized amylose 3,5-dimethylphenylcarbamate-based sorbent was used to investigate the balance between electrostatic interactions and solvophobic interactions, with complementary effects on solute retention behavior when the isopropanol (IPA) concentration was altered. It was proposed that in both normal- and reversed-phase modes, information on the retention mechanisms could be obtained by observing the curvature of the logarithm of the retention factor versus the logarithm of the IPA concentration, and the slope values of the curves were related to the number of displaced IPA molecules upon solute adsorption. Using the proposed model and the two-site adsorption model, the retention behaviors of pantolactone (PL) enantiomers in both normal- and reversed-phase modes were investigated. The PL-sorbent interactions were classified into four types: electrostatic/enantioselective, electrostatic/nonselective, solvophobic/enantioselective, and solvophobic/nonselective. At IPA concentrations below 50 vol.% in n-hexane, the retention behaviors of PL were dominated by electrostatic/enantioselective sites, whereas at IPA concentrations beyond 50 vol.%, the solvophobic interactions of PL-sorbent were strengthened and mostly nonselective. By contrast, in the reversed-phase mode, a reverse in the enantiomeric elution order of PL was observed at 10 vol.% IPA, and considerably different enantioselectivity behaviors were found below and above 20 vol.%, indicating an abrupt change in the sorbent molecular environment. At IPA concentrations beyond 40 vol.%, the presence of PL-sorbent electrostatic interactions enhanced chiral recognition.
Assuntos
2-Propanol , Amilose/análogos & derivados , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Fenilcarbamatos , 2-Propanol/química , Amilose/química , Fenilcarbamatos/química , Eletricidade EstáticaRESUMO
As the consequences of climate change become apparent, metabolic engineers and synthetic biologists are exploring sustainable sources for transportation fuels. The design and engineering of microorganisms to produce bio-gasoline and other biofuels from renewable feedstocks can significantly reduce dependence on fossil fuels as well as lower the emissions of greenhouse gases. A significant amount of research over the past two decades has led to the development of microbial strains for the production of advanced fuel compounds. Crucial to these efforts are robust methods to quantify the amount of the biofuel compound being produced as well as the other metabolites that might be present during fermentation. Here, we provide a protocol for the quantification of branched-chain alcohols, specifically isobutanol and isopropanol, using high-performance liquid chromatography (HPLC).
Assuntos
Álcoois/análise , Biocombustíveis/análise , Cromatografia Líquida de Alta Pressão/métodos , 2-Propanol/análise , 2-Propanol/química , Álcoois/metabolismo , Butanóis/análise , Butanóis/química , Fermentação/fisiologia , Engenharia Metabólica/métodos , Biologia Sintética/métodosRESUMO
Amino acids and peptides are essential components in the biochemical industry. The final products are employed in a wide range of applications and are often synthesized by fermentation and purified in a complex downstream process. One possible separation step is using an additional solvent to lower the solubility of the desired product and, thus, promote the crystallization of the particular component. Therefore, it is crucial to have accurate knowledge of the solubility of these components. In this work, the solubilities of 20 proteinogenic amino acids and 21 peptides in aqueous 2-propanol solutions were gravimetrically determined. Additionally, the pH values of the saturated liquid phases were measured and the crystal structures of solid crystals were analysed using X-ray diffraction. The anti-solvent 2-propanol caused a decrease in the solubilities of the amino acids and peptides upon increasing its mass fraction. Exceptions were found for amino acids with aromatic substituents, l-phenylalanine and l-tyrosine. The solubility of 15 amino acids and 18 peptides was successfully modelled using the equation of state PC-SAFT that used recently determined melting properties of the amino acids and peptides as input data.
Assuntos
2-Propanol/química , Aminoácidos/química , Peptídeos/química , Cristalografia por Raios X , Concentração de Íons de Hidrogênio , Modelos Moleculares , Solubilidade , Soluções , Água/químicaRESUMO
The removal of plant pigments such as ß-carotene is an aspect of vegetable oil processing often desired by the food and pharmaceutical industries. Adsorption of ß-carotene to acid-activated clay (AAC) is a well-established method for purification. Despite this, the removal mechanism of ß-carotene is not well understood. UPLC-MS/MS analysis of surface compounds extracted from ß-carotene-AAC (BC-AAC) complexes show that AAC acts as an oxidiser. Oxidation products detected included canthaxanthin and 3',4'-didehydro-ß-caroten-4-one. AAC had surface water exchanged with an 18O labelled water and was then exposed to ß-carotene. Carotenoids labelled with 18O were produced from this reaction, suggesting surface water is necessary for ß-carotene removal.
Assuntos
Indústria de Processamento de Alimentos/métodos , Óleos de Plantas/química , beta Caroteno/análise , beta Caroteno/isolamento & purificação , 2-Propanol/química , Cantaxantina/análise , Cantaxantina/química , Carotenoides/análise , Carotenoides/química , Cromatografia Líquida/métodos , Argila/química , Oxirredução , Isótopos de Oxigênio/química , Extratos Vegetais/análise , Extratos Vegetais/química , Solventes , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos , Água/química , beta Caroteno/químicaRESUMO
The current research work focuses on understanding the reported discrepancies and our observations in the dissolution profiles of warfarin sodium tablets and potential patient-based failure modes during oral warfarin therapy. It was hypothesized that freely soluble crystalline warfarin sodium (WARC) at first transforms into noncrystalline warfarin sodium (WARNC) under stress conditions. The WARC â WARNC conversion facilitates the rapid formation of the poorly soluble unionized form, which could lead to dissolution failures and potential poor in vivo performance. Depressed warfarin concentrations locally in the gastrointestinal tract (GIT) may in turn lead to inadequate absorption and thereby affect bioavailability. A low volume two-stage dissolution method was developed to mimic in vivo GIT conditions. Warfarin sodium tablets exposed to room temperature and 75% relative humidity for 1 week showed approximately 23% decrease in drug release. The decline in drug release supports the hypothesis that WARNC is converted to the unionized form faster than WARC does under the same conditions. Solid state characterization (powder X-ray diffractometry and differential scanning calorimetry) data demonstrated the disproportionation of warfarin sodium to unionized warfarin after solubility and dissolution studies. The findings support the hypothesis and a possible failure mode of warfarin sodium tablets. This work is a second case study from our laboratory on narrow therapeutic index drug products in which the instability of the solid state of the drug substance is potentially responsible for observed clinical failures.