Sodium citrate as an eco-friendly complexing agent for the bioscouring treatment of the cellulosic/lignocellulosic fabrics

A 50% of cotton–50% of flax fabric was subjected to an enzymatic treatment (bioscouring) in ultrasound for removing the compounds which could negatively affect the further specific technological processes as whitening and dyeing. During the scouring process, some parameters of the fabrics are improved. Even EDTA is usually used as a chelating agent in the pretreatments of the fabrics, recent studies aimed to identify new biodegradable complexing agents. In this study, we present the results obtained for bioscouring treatment of the cellulosic/lignocellulosic fabrics in the presence of sodium citrate as a complexing agent. The treatments were made in 0.1 M phosphate buffer of pH 8 and ultrasound media. The samples were immersed in an aliquot containing the commercial pectinolytic product BEISOL PRO, Denimcol Wash-RGN as a surfactant and sodium citrate or EDTA (ethylenediaminetetraacetic acid). The reactions were conducted by varying the enzyme concentration and action time using a central, rotatable second-order compound program. All the parameters determined after bioscouring [weight loss, hydrophilicity, whiteness index, yellowness index, tensile strength, elongation at break, the relative absorbance (A₁₇₃₁) from FT-IR spectra, color strength (K/S) and color difference (ΔE*ab)] of the investigated samples showed in the case of sodium citrate (an eco-friendly biodegradable compound) treatments better or comparable values to treatments conducted using EDTA (non-biodegradable compound).     

Tailored doxycycline delivery from MCM-41-type silica carriers

Doxycycline, an antibiotic from the tetracycline class with a broad spectrum of activity, was used to prepare drug delivery systems based on pristine and functionalized mesostructured silica supports. MCM-41-type materials with different textural, structural, and surface properties were used to assess their influence on the drug release kinetics. Small- and wide-angle XRD, FTIR spectroscopy and N₂ adsorption/desorption isotherms were used to characterize the carriers before and after doxycycline loading. The drug release experiments were performed in vitro in 0.2 M phosphate buffer solution at 37 °C, and the slowest drug release kinetics was obtained for magnesium-modified MCM-41 carrier. All drug-loaded materials exhibited good antibacterial activity against Klebsiella pneumoniae ATCC 10031 strain, similar to the drug alone.     

Interaction of 1-methyl-1-({2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-4-yl}methyl) piperidinium chloride with β-CD: spectroscopic,calorimetric and molecular modeling approaches

Spectroscopic investigation supported by molecular modeling methods has been used to describe the inclusion complex of β-cyclodextrin (β-CD) with 1-Methyl-1-({2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-4-yl}methyl) piperidinium chloride (1MPTMPC) in solution and in solid state. The formation of inclusion complex between the β-CD and the 1MPTMPC has been investigated both in solution and in the solid state. Solution-state complexation between the 1MPTMPC and β-CD was established using ¹H NMR spectroscopy and isothermal titration calorimetry (ITC). From the ¹H NMR spectroscopic studies, 1:1 complex stoichiometry was deduced with an association constant (K) of 925 M^?1. Using an independent binding model, the ITC technique provides a K value of the same order with the one determined by NMR and the thermodynamic parameters ΔH, ΔS and ΔG which reveals driving forces involved during complex formation. The formation of the solid inclusion compound was confirmed by X-ray powder diffraction and differential scanning calorimetry. The most probable conformation of the inclusion complex obtained through a molecular docking investigation corroborates well to ROESY experiment.     

Thermal behaviour of <Emphasis Type="Italic">sym</Emphasis>-octahydroacridines and their corresponding N(10)-oxides

We present and discuss results on the thermal behaviour of 1,2,3,4,5,6,7,8-octahydroacridine (OHA), together with six 9-substituted congeners, i.e. R = –Br, –OCH₃, –NH₂, –NO₂, –OH, and furyl (–C₄H₃O), and their corresponding N(10)-oxides, under nitrogen atmosphere and with alumina as reference, at a heating rate of 5 °C min^?1 from room temperature to 300 °C. Chromatography has been carried out on aluminium sheets, with aluminium oxide 60 F254 neutral (Merck). Melting effects are observed for almost all compounds in their corresponding curves, precisely determined by using a Boetius apparatus. Homolysis of the carbon-substituent bond occurs in most cases, a phenomenon which is consistent with the values of the bond dissociation energy. For all compounds, except for hydroxyl congeners, thermal decomposition started with an endothermic peak. Octahydroacridines readily decompose into volatile products, an effect which correlates with their low melting points, while little amounts of residue remain in place of the aromatic amines compared to the N(10)-oxides. The presence of N–O bonds greatly influences the thermal stability of the compound, in the sense of increasing it compared with the parent amine. Quantitative studies of the decomposition products reveal that the melting points, the 9-position substituent, and N–O bond all play an important role upon the thermal behaviour. Mechanistic/kinetic pathways are also proposed as such results are important in further designing laser processing protocols, i.e. matrix-assisted pulsed laser evaporation (MAPLE) or laser-induced forward transfer (LIFT), for thin film deposition and/or device printing.     

Kinetics of thiophene hydrodesulfurization over a supported Mo–Co–Ni catalyst

In this study, the kinetics of thiophene (TH) hydrodesulfurization (HDS) over the Mo–Co–Ni-supported catalyst was investigated. Trimetallic catalyst was synthesized by pore volume impregnation and the metal loadings were 11.5 wt % Mo, 2 wt % Co, and 2 wt % Ni. A large surface area of 243 m²/g and a relatively large pore volume of 0.34 cm³/g for the fresh Mo–Co–Ni-supported catalyst indicate a good accessibility to the catalytic centers for the HDS reaction. The acid strength distribution of the fresh and spent catalysts, as well as for the support, was determined by thermal desorption of diethylamine (DEA) with increase in temperature from 20 to 600 °C. The weak acid centers are obtained within a temperature range between 160 and 300 °C, followed by medium acid sites up to 440 °C. The strong acid centers are revealed above 440 °C. We found a higher content of weak acid centers for fresh and spent catalysts as well as alumina as compared to medium and strong acid sites. The catalyst stability in terms of conversion as a function of time on stream in a fixed bed flow reactor was examined and almost no loss in the catalyst activity was observed. Consequently, this fact demonstrated superior activity of the Mo–Co–Ni-based catalyst for TH HDS. The activity tests by varying the temperature from 200 to 275 °C and pressure from 30 to 60 bar with various space velocities of 1–4 h^?1 were investigated. A Langmuir–Hinshelwood model was used to analyze the kinetic data and to derive activation energy and adsorption parameters for TH HDS. The effect of temperature, pressure, and liquid hourly space velocity on the TH HDS activity was studied.     

Statistical Characterization of the Phytochemical Characteristics of Edible Mushroom Extracts

The antioxidant activity, total phenolic content, and total flavonoid content of 10 edible mushrooms species, including cultivated (Pleurotus ostreatus, Agaricus bisporus white and brown) and wild (P. ostreatus, Macrolepiota procera, Cantharellus cibarius, Russula vesca, Russula alutacea, Boletus edulis and Agaricus campestris), were determined. The extraction was performed using water and 50% water–ethanol and the caps and stipe were investigated separately. Water was the most appropriate solvent for phenolic compounds regardless of the sample. In contrast, the presence of ethanol in the solvent increased the extraction of flavonoids for cultivated P. ostreatus (caps and stipe), and wild R. alutacea, R. vesca, A. campestris, P. ostreatus (only caps) and C. cibarius, M. procera (only stipe). Significant differences between the antioxidant activities of the samples were registered in relationship with the different solvents. The antioxidant activity of water extract of dried A. bisporus brown (cultivated) showed the strongest 1,1-diphenyl-2-picrylhydrazyl radicals-scavenging assay (88.64%), while the B. edulis hydroalcoholic extract contained 74.93%. A detailed investigation into the functional group of phenolics and other organic compounds responsible with the antioxidant activity has been performed using Fourier transform infrared spectroscopy. The infrared spectra showed that the solvent-type directly influences the extraction process and, hence, the antioxidant activity. The present study contributes to information concerning mushrooms as sources of biologically active compounds. To investigate the correlations between phytochemical characteristics (i.e., phenolics, flavonoids and antioxidant activity) closely related to nature of solvents, the statistical analysis was performed.     

Spectrofluorimetric determination of phenyl-<Emphasis Type="Italic">β</Emphasis>-naphthylamine used as rubber antioxidant

Phenyl--naphthylamine (PBN) used as rubber antioxidant was found to have native fluorescence. A spectrofluorimetric method for determination of PBN in multicomponent mixtures of polymer additives is described. The apparent excitation and fluorescence wavelengths used are 348 and 413.5 nm, respectively. Maximum fluorescence intensity is obtained by irradiating PBN dissolved in ethanol, at room temperature. The fluorescence varies linearly with the concentration of PBN in the range of 0.04–4 g mL^–1. The accuracy and precision of the method are reported.     

Thermal behavior of some N,N-dimethylbiguanide derivatives displaying antimicrobial activity

N,N-Dimethylbiguanide derivatives (HDMBG)X, where X=CH₃COO (1), Cl (2) and NO₃ (3) respectively, exhibit in vitro antimicrobial activity on representative bacterial and fungal strains. The presence of N,N-dimethylbiguanidium ion for all derivatives was evidenced by IR and ¹H NMR spectra. Thermal analysis gave information on their decomposition steps and also on the accompanying thermodynamic effects. According to TG and DTG curves processes as melting, oxidative degradation as well as oxidative condensation of –C=N– units occur. The different nature of the anions results different melting points. Paracyanide formation at various condensation degrees was observed.     

Temperature and pH effects on the kinetics of 2-aminophenol auto-oxidation in aqueous solution

The kinetics of the auto-oxidation of 2-aminophenol (OAP) to 2-amino-phenoxazin-3-one (APX) was followed in air-saturated aqueous solutions and the influence of temperature and pH on the auto-oxidation rate was studied. The kinetic analysis was based on a spectrophotometric method following the increase of the absorbance of APX. The process follows first order kinetics according to the rate law—d[OAP]/dt=k′[OAP]. The experimental data, within the pH range 4–9.85, were analyzed using both differential and incremental methods. The temperature variation of the overall rate constant was studied at pH=9.85 within the range 25–50°C and the corresponding activation energy was evaluated.     

NMR Study of the Inclusion Complexes of Carboxy-Phenoxathiin Derivatives with β-Cyclodextrin

The inclusion complexes of the carboxylate forms of 3-carboxy-(I) and 2-carboxy-phenoxathiin (II) with -cyclodextrin were studied by bothone- and two-dimensional NMR spectroscopy. The analysis of the induced chemical shifts of theguests in the presence of different amounts of the host indicates the formation of complexes with 1:1stoichiometry and association averaged pK values of 3.75 (I) and 4.4 (II). Thequalitative analysis of cross peaks in the ROESY spectra support the inclusion of the guests in the cavitywith the substituted phenyl ring, the COO^- group being in the proximity of the primary rim.