The effect of microfibrillated cellulose addition on drying shrinkage and dimensional stability of wood-free paper

Microfibrillated cellulose (MFC) is known to enhance strength properties of paper. Improved strength usually means increased bonding which is strongly connected to dimensional instability of paper. Dimensional instability is due to changes in moisture content of paper; when paper is moistened it expands and when dried, it shrinks. Hygroexpansion is linked to end-use problems and excessive drying shrinkage consumes strength potential. Effective use of materials requires controlling of these phenomena. There isn’t yet data concerning dimensional stability of papers containing MFC which restricts wider use of MFC. Main objective of the work was to evaluate dimensional stability of wood-free paper containing different amounts of MFC. Sheets were dried with different methods to see how drying strains effected on drying shrinkage and hygroexpansion. Also tensile strength was measured to find out the effect of MFC. Results were compared to sheets containing kraft fines and in some test points cationic starch was used alongside with MFC. MFC increased the dimensional instability of freely dried sheets. As the amounts of MFC increased the effects on dimensional stability became more severe. However the fineness of MFC didn’t play any important role. Both hygroexpansion and drying shrinkage were decreased with cationic starch addition. Prevention of drying shrinkage over powered the effects of additives on hygroexpansion. Tensile strength improved up till 7 % addition amount which could be set as the upper limit of MFC addition when paper preparation and tensile strength are concerned.

The stability of right- and left-handed alpha-helices as a function of monomer chirality

Poly-L-alanine forms stable right-handed alpha-helices, whereas Poly-D-alanine is stable as left-handed alpha helices.

Effect of reducing and replacing pork fat on the physicochemical, instrumental and sensory characteristics throughout storage time of small caliber non-acid fermented sausages with reduced sodium content

The effect of pork fat reduction (from 44% to 20% final fat content) and its partial substitution by sunflower oil (3% addition) on the physicochemical, instrumental and sensory properties throughout storage time of small caliber non-acid fermented sausages (fuet type) with reduced sodium content (with partial substitution of NaCl by KCl and K-lactate) and without direct addition of nitrate and nitrite (natural nitrate source used instead), was studied. Results showed that sausages with reduced fat (10% initial fat content) and with acceptable sensory characteristics can be obtained by adding to the shoulder lean (8% fat content) during the grinding, either 3.3% backfat (3% fat content) or 3% sunflower oil, both previously finely comminuted with lean. Furthermore, sunflower oil showed to be suitable for partial pork backfat substitution in very lean fermented sausages, conferring desirable sensory properties similar to those of sausages with standard fat content. The sensory quality of the sausages was maintained after three-month cold storage in modified atmosphere.

Amphotericin B associated with triglyceride-rich nanoemulsion: stability studies and in vitro antifungal activity

Amphotericin B (AB) is the standard drug for invasive fungal infection therapy. It has a broad spectrum of activity and it is the best antifungal available against most yeasts and molds. Its therapeutic use, however, is limited by significant side effects, leading to a low therapeutic index when it is used as the traditional formulation (Fungizone®). Due to self-association, AB can form pores in cholesterol-containing membranes. We propose a triglyceride-rich nanoemulsion as a delivery system for AB in low levels of aggregation to reduce the toxicity against host cells.

Determinação simultânea dos ácidos orgânicos tartárico, málico, ascórbico e cítrico em polpas de acerola, açaí e caju e avaliação da estabilidade em sucos de caju

The aim of the present study was determining the main organic acids in pulp and juices, as well as evaluating their stability, after opening the package, by liquid chromatography in a C18 column with isocratic elution and UV detection. In açaí pulp tartaric, malic and citric acids were found. Cashew samples presented all of the organic acids evaluated, besides high concentrations of ascorbic and malic acids. Acerola pulp had the highest ascorbic acid concentration. A small decrease in organic acid content during storage was observed. Malic and citric acids seem to be more stable than tartaric and ascorbic acids.

Estabilidade de compostos bioativos em polpa congelada de amora-preta (Rubus fruticosus) cv. Tupy

Rubus fruticosus (Rosaceae), popularly known as Blackberry, is a highly nutritious fruit, rich in bioactive compounds. Their stability during processing has been the focus of several studies. This work describes the evaluation of the stability of the main phytochemicals of pulp from blackberry cv. Tupy, stored under different temperature conditions for six months. The storage at -10 °C was not sufficient to cause significant changes in total phenolics content, anthocyanins content and antioxidant capacity during two months of storage. Likewise, at -18 °C, total phenolics content and antioxidant capacity were kept for four months, but total anthocyanins and β-carotene content were kept for two and six months of storage, respectively.

Development and validation of a stability-indicating UPLC method for rosuvastatin and its related impurities in pharmaceutical dosage forms

The present work describes a novel stability-indicating reversed-phase ultra performance liquid chromatography method for the separation and quantification of rosuvastatin (RSV) and its related impurities in the pharmaceutical dosage forms under forced degradation conditions. An unknown degradation impurity detected in the acid degradation was identified by using quadrupole time-of-flight mass spectrometry. The chromatographic separation was carried out on C-18 column (100 x 2.1 mm, 1.7 μm) using isocratic elution with methanol and 0.1% trifluoroacetic acid (50:50). The total run time was 12 min within which RSV as well as all related impurities and degradation products were separated. The developed method was validated for RSV and related impurities in pharmaceutical dosage forms.

Chemical stability of enalapril maleate drug substance and tablets by a stability-indicating liquid chromatographic method

The chemical stability of enalapril drug substance and tablets was studied by a stability-indicating liquid chromatographic method. Stress testing was performed on drug substance under various conditions. Accelerated stability testing was carried out for different formulations of enalapril tablets. Chromatographic separation was achieved on a RP-18 column, using a mobile phase of methanol phosphate buffer at 1.0 mL min"1 and UV detection. Degradation of the drug substance was greater under hydrolytic conditions. After 180 days of accelerated stability testing most enalapril tablets showed more than 10% of degradation. Enalapril drug substance and tablets showed instability under stress and accelerated testing respectively, with possible implications on the therapeutic activity.

Electrodeposition of gold from formaldehyde-sulfite baths: bath stability and deposits characterization

It was investigated Au(I)-sulfite baths containing formaldehyde. As a result, high stability was achieved for baths containing formaldehyde concentration close to 10 mL L-1 with a lifetime superior to 600 days. On the other hand, cyclic voltammograms indicated that the increase of formaldehyde concentration in the bath promotes decreasing of the maximum cathodic current, so that, if the formaldehyde concentration is high, the surface areal concentration of gold will be low. Also, the lowest surface roughness was obtained for 10 mL L-1 of formaldehyde.

Development and validation of a stability-indicating HPLC method for the determination of buclizine hydrochloride in tablets and oral suspension and its application to dissolution studies

A method using liquid chromatography has been developed and validated for determination of buclizine in pharmaceutical formulations and in release studies. Isocratic chromatography was performed on a C18 column with methanol:water (80:20 v/v, pH 2.6) as mobile phase, at a flow rate of 1.0 mL/min, and UV detection at 230 nm. The method was linear, accurate, precise, sensible and robust. The dissolution test was optimized and validated in terms of dissolution medium, apparatus agitation and rotation speed. The presented analytical and dissolution procedures can be conveniently adopted in the quality and stability control of buclizine in tablets and oral suspension.

Quantificação sérica de vitamina C por CLAE-UV e estudo de estabilidade

Vitamin C, an exogenous antioxidant, is essential to human health. In this study, a method was validated to serum vitamin C quantification by HPLC-UV. Its stability with and without the use of tris [2-carboxy-ethyl] phosphine hydrochloride (TCEP), at -20 and -80 °C, in serum and supernatant were also evaluated. Analysis showed r² > 0.99, precision CV% < 15% and % bias < 15%, being linear, precise and accurate. The stability test revealed that using TCEP in serum storage at -20 and -80 °C or in supernatant at -80 °C the vitamin C levels remain stable for 30 and 12 days, respectively.

Development and validation of a novel stability indicating RP-UPLC method for simultaneous determination of nizatidine, methylparaben and propylparaben in oral liquid pharmaceutical formulation

A selective and accurate stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed and validated for the simultaneous determination of nizatidine, methylparaben and propylparaben in pharmaceutical oral liquid formulation. The separation was achieved on Acquity UPLC TM HSS T3 1.8 µm column by using mobile phase containing a gradient mixture of solvent A (0.02 Mol L-1 KH2PO4, pH 7.5) and B (60:40 v/v mixture of methanol and acetonitrile) at flow rate of 0.4 mL min-1. Drug product was exposed to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The developed method was validated as per international ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness.

Stability indicating HPLC method for simultaneous determination of moxifloxacin hydrochloride and ketorolac tromethamine in pharmaceutical formulations

A simple, RP-HPLC method was established for determining moxifloxacin and ketorolac in pharmaceutical formulations. Moxifloxacin, ketorolac and their degradation products were separated using C8 column with methanol and phosphate buffer pH 3.0 (55:45 v/v) as the mobile phase. Detection was performed at 243 nm using a diode array detector. The method was validated using ICH guidelines and was linear in the range 20-140 µg mL-1 for both analytes. Good separation of both the analytes and their degradation products was achieved using this method. The developed method can be applied successfully for the determination of moxifloxacin and ketorolac.

Stability-indicating comparative methods using mekc and lc for determination of olmesartan medoxomil

A stability-indicating method using MEKC was validated for the analysis of olmesartan medoxomil in tablets. Successful separation was achieved using a fused silica capillary (40 cm x 50 µm i.d.); background electrolyte consisted of a combination of 10 mmol L-1 borate buffer and 5 mmol L-1 anionic detergent sodium dodecyl sulfate (95:5; v/v) pH 6.5; hydrodynamic mode at 50 mBar for 5 s; 25 kV separation voltage at 25 ºC; and column temperature 25 ºC with detection at 257 nm. The proposed method, validated following ICH guidelines, was applied to the determination of this antihypertensive with good results compared with an LC method.