Formulasi dan Uji Stabilitas Sediaan Suspensi Ekstrak Rimpang Zingiber zerumbet

Zingiber zerumbet (L) Smith rhizome has been used traditionally as an herbal medicine in Indonesia. Isolated extracts and metabolites of Z. zerumbet have shown anti-inflammatory, antioxidant, antidiabetic, anticancer, antimicrobial, analgesic and antiviral activity. The form of suspension is carried out to facilitate the utilization of the main bioactive content, zerumbone, which is difficult to dissolve in water. The formulation of suspension is based on variations in the concentration of Z. zerumbet extract, which is 2.5% (formulation 1), 5% (formulation 2), and 10% (formulation 3). To determine the physical stability, the evaluation is carried out, namely: organoleptic test, density, viscosity, redispersibility and pH. The results showed all three formulations did not provide organoleptic changes for 30 days, >1 g/cm3 density, good redispersibility, and pH of 6. The viscosity of each formulation is quite varied i.e., 3.74 cp; 4,27 cp; and 11.8 cp. Formulation 3 is determined as the best formulation based on its viscosity which is closest to the standard range of good suspension viscosity according to the SNI.

The Effect of Cellulose Nanocrystal Suspension Treatment on Suspension Viscosity and Casted Film Property

Cellulose nanocrystals (CNCs) have attracted significant interest in different industrial sectors. Many applications have been developed and more are being explored. Pre-treatment of the suspension plays a critical role for different applications. In this study, different pre-treatment methods, including homogenization, ultrasonication, and mixing with a magnetic stirrer were applied to a CNC suspension. After treatment, the rheological behaviors of the treated CNC suspensions were characterized using a rotational viscometer. The treated suspensions were then used to cast films for characterization by ultraviolet-visible (UV-Vis) and Fourier transform near-infrared spectroscopy (FT-NIR). All the CNC suspensions demonstrated a shear thinning phenomena. Homogenization or ultrasonication significantly decreased the suspension viscosity compared with the suspension mixed by a magnetic stirrer. The viscosity of CNC suspension changed with time after treatment and settlement of treated CNC suspensions in room conditions increased the viscosity dramatically with time. Different UV and visible light interferences were observed for the CNC films generated from suspensions treated by different methods. The degree of crystallinity of the CNC films evaluated by FT-NIR showed that the film from suspension treated by homogenization and ultrasonication has the highest degree of crystallinity. Pre-treatments of CNC suspension affected the suspension viscosities and formed film properties.

The Effect of High Lignin Content on Oxidative Nanofibrillation of Wood Cell Wall

Wood from field-grown poplars with different genotypes and varying lignin content (17.4 wt % to 30.0 wt %) were subjected to one-pot 2,2,6,6-Tetramethylpiperidin-1-yl)oxyl catalyzed oxidation and high-pressure homogenization in order to investigate nanofibrillation following simultaneous delignification and cellulose oxidation. When comparing low and high lignin wood it was found that the high lignin wood was more easily fibrillated as indicated by a higher nanofibril yield (68% and 45%) and suspension viscosity (27 and 15 mPa·s). The nanofibrils were monodisperse with diameter ranging between 1.2 and 2.0 nm as measured using atomic force microscopy. Slightly less cellulose oxidation (0.44 and 0.68 mmol·g−1) together with a reduced process yield (36% and 44%) was also found which showed that the removal of a larger amount of lignin increased the efficiency of the homogenization step despite slightly reduced oxidation of the nanofibril surfaces. The surface area of oxidized high lignin wood was also higher than low lignin wood (114 m2·g−1 and 76 m2·g−1) which implicates porosity as a factor that can influence cellulose nanofibril isolation from wood in a beneficial manner.

Scaling seismic fault thickness from the laboratory to the field

<p>Pseudotachylytes originate from the solidification of frictional melt, which transiently forms and lubricates the fault plane during an earthquake. Here we observe how the pseudotachylyte thickness <em>a</em> scales with the relative displacement <em>D</em> both at the laboratory and field scales, for measured slip varying from microns to meters, over six orders of magnitude. Considering all the data jointly, a bend appears in the scaling relationship when slip and thickness reach ∼1 mm and 100 µm, respectively, i.e. <em>M</em><sub>W</sub> > 1. This bend can be attributed to the melt thickness reaching a steady‐state value due to melting dynamics under shear heating, as is suggested by the solution of a Stefan problem with a migrating boundary. Each increment of fault is heating up due to fast shearing near the rupture tip and starting cooling by thermal diffusion upon rupture. The building and sustainability of a connected melt layer depends on this energy balance. For plurimillimetric thicknesses (<em>a</em> > 1 mm), melt thickness growth reflects in first approximation the rate of shear heating which appears to decay in <em>D</em><sup>−1/2</sup> to <em>D</em><sup>−1</sup>, likely due to melt lubrication controlled by melt + solid suspension viscosity and mobility. The pseudotachylyte thickness scales with moment <em>M</em><sub>0</sub> and magnitude <em>M</em><sub>W</sub>; therefore, thickness alone may be used to estimate magnitude on fossil faults in the field in the absence of displacement markers within a reasonable error margin.</p>

Физико-химический анализ структуры и свойств нанокомпозитов полимер/углеродные нанотрубки, полученных из раствора

The structural (fractal) model, applied earlier for polymer solutions, was used for description of viscosity of aqueous suspensions of carbon nanotubes. The indicated model treates adequately the dependence of suspension viscosity on concentration of carbon nanotubes. At reaching of percolation theshold of this nanofiller a sharp growth of viscosity of aqueous suspensions is observed. The model reflects adequately also the dependence of viscosity on geometry of carbon nanotubes. A knowledge of nanofiller structure, characterizing by its fractal dimension, allows to predict reinforcement degree of solid-state polymer nanocomposites.

Numerical Simulation of the Rheological Behavior of Nanoparticulate Suspensions

Nanoparticles significantly alter the rheological properties of a polymer or monomeric resin with major effect on the further processing of the materials. In this matter, especially the influence of particle material and disperse properties on the viscosity is not yet understood fully, but can only be modelled to some extent empirically after extensive experimental effort. In this paper, a numerical study on an uncured monomeric epoxy resin, which is filled with boehmite nanoparticles, is presented to elucidate the working principles, which govern the rheological behavior of nanoparticulate suspensions and to simulate the suspension viscosity based on assessable material and system properties. To account for the effect of particle surface forces and hydrodynamic interactions on the rheological behavior, a resolved CFD is coupled with DEM. It can be shown that the particle interactions caused by surface forces induce velocity differences between the particles and their surrounding fluid, which result in increased drag forces and cause the additional energy dissipation during shearing. The paper points out the limits of the used simulation method and presents a correction technique with respect to the Péclet number, which broadens the range of applicability. Valuable information is gained for a future mechanistic modelling of nanoparticulate suspension viscosity by elucidating the interdependency between surface forces, shear rate and resulting drag forces on the particles.

Design and fabrication of ceramic hollow fiber membrane derived from waste ash using phase inversion-based extrusion/sintering technique for water filtration

Low-cost green ceramic hollow fiber membranes (CHFM) were successfully designed and fabricated from the industrial waste ash, palm oil fuel ash (POFA) via phase inversion-based extrusion/sintering techniques for water filter application. The extrusion process parameters such as suspension viscosity, air gap distance, and bore fluid flow rate were systematically explored to produce the membrane with the desired morphology. A high suspension viscosity would result in a small macro-voids structure. Moreover, a high air gap distance would induce fiber with long macro-voids structure, while a low bore fluid flow rate would lead to the formation of distorted lumen structure. The effect of sintering temperature towards CHFM was also studied in detail. An increase in sintering temperature improved the membrane bending strength, but also adversely affected the pure water flux due to lower porosity and higher tortuosity. The developed membranes achieved excellent bending strengths of > 75 MPa at relatively low sintering temperatures than the alternative ceramic counterparts, due to its high potassium oxide, K2O content, which acted as the low melting point sintering aid. The relatively low sintering temperature of POFA-derived CHFMs could reduce the energy consumption and sintering duration, which could be more economically attractive, as compared to their ceramic counterparts, thus benefiting industrial users.

MECHANISMS OF TRAPPING FINE DUST IN WET DUST COLLECTING APPARATUS

The high efficiency of intensive operation of wet scrubbers is the result of a simultaneous formation of different mechanisms of dust particle collectors. The collectors can be understood as droplets of atomised liquid, bubbles formed in the conditions of intensive barbotage, liquid surface and wet surfaces. All collectors are formed during the operation of the circulating unit. The deposition of dust particles from gas occurs as a result of centrifugal forces and secondary circulations in the guide duct as well as the effect of the water curtain, liquid barbotage and the flow of dusty gas through the droplet-splash layer. Discussions substantiating the possibility of confirming the effect of suspension viscosity on the efficiency of the dust collection process can be related both to the analysis of basic mechanisms affecting the deposition of particles on liquid collectors and the conditions of generating collectors. In total liquid recirculation in wet dedusting equipment, concentration of solids in a liquid rises. In such conditions, a gradual decrease in their dedusting efficiency is possible. The effect depends on dust physiochemical properties, kinetic energy of particles, the type of equipment used, and specifically on the way of organization of the contact of the liquid and gas phases. Studies of the effectiveness of dedusting depending on various factors are given in the next article by the same authors.