Mixture Of Distilled Water Research Articles

Determination of Phenolic Composition of Tilia Tomentosa Flowers Using UPLC-ESI-MS/MS

Phenolic compounds, which are secondary metabolites of plants, are one of the main groups of compounds that provide antiallergic, antiinflammatory, antimicrobial, antioxidant, cardioprotective properties of medicinal and aromatic plants. These broad physiological effects that they possess lead researchers to examine the phenolic contents of plants. Tilia tomentosa Moench is one of 45 species belonging to Tiliaceae family, and the use of flowers in traditional treatment methods is quite common. Although it is well known that T. tomentosa flowers are rich in phenolics with various biological functions, there is no recent study on determination of phenolic compounds of T. tomentosa flowers using UPLC-ESI-MS/MS. In this study, firstly, T. tomentosa flowers were extracted using hexane and volatile oil fractions were separated from the plant. Distilled water:methanol (50:50) mixture was added to the remaining flower part at 40 °C and that subjected to extraction for 15 min. The obtained extract was filtered and dried in a lyophilizer at -70 °C. The residue was redissolved in a mixture of distilled water:methanol (80:20). The sample was analyzed by UPLC-MS/MS (Waters Acquity Ultra Performance LC, Xevo TQ-S MS/MS) by passing through Macherey-Nagel Chromafil Xtra PTFE-20/25 0.20 μm filters. According to the analysis results, 3,4-dihydroxybenzoic acid (66.820 mg/kg), myricetin (29.395 mg/kg), rutin (21.421 mg/kg), ferulic acid (12.334 mg/kg) and 3,4-dihydroxybenzaldehyde (10.383 mg/kg) were detected. T. tomentosa flowers have great potential to usage in industries such as food, medicine and cosmetic due to its rich content of phenolics.

Effect of Temperature and Humidity on Electrical Properties of Organic Orange Dye Complex Films

<p>In this study the effect of temperature and humidity on electrical properties of organic orange dye (OD) complex with vinyl-ethynyl-trimethyl-piperidole (VETP) have been examined. Thin films of OD (C<sub>17</sub>H<sub>17</sub>N<sub>5</sub>O<sub>2</sub>) and VETP (C<sub>12</sub>H<sub>19</sub>NO) complex were deposited from 10 wt.% (5 wt.% of each matter) solution in mixture of distilled water (80%) and spirit. The films were grown at room temperature under normal gravity conditions, <em>i.e.</em>, 1 g and in a spin coater at an angular speed of 300 RPM. The Cu/OD-VETP/Cu surface type samples were fabricated and their low frequency (10 Hz) AC electric characteristics were evaluated for the temperature range 30-95 °C at ambient humidity of 45-80%. It was observed that at normal conditions the conductivity of the samples is temperature dependent and shows semi-conductive behavior with activation energy of 0.55 eV. It was found that with increase in humidity the resistance of the samples decreases and at humidity values equal to 60-70% the irreversible transition from semi-conductive to conductive state takes place. It is supposed that in the former state the conductive matrix is formed due to incorporation of the water molecules into OD-VETP complex.</p>

Experimental study of the sensible heat storage in the water/TiO2 nanofluid enclosed in an annular space

This article is devoted to an experimental study of heat transfer during a sensible heat storage cycle (charging/discharging) in a vertical cylindrical system. The experimental setup consists of two cylindrical tanks filled respectively with hot and cold water, a test bench, and measurement instruments. The test bench, thermally insulated with glass wool, is also composed of two vertical concentric tubes whose annular space contains the used nanofluid (the mixture of distilled water and titanium dioxide nanoparticles). The heat transfer fluid (HTF) flows in the upward direction of the inner tube (HTF pipe). Adequate methods were used to prepare titanium dioxide nanoparticles for which the diameter is less than 20nm. Both convective heat transfer coefficient between external inner tube wall and nanofluid, and heat flux densities during storage cycle, were evaluated. The effect of nanofluid mass concentration (0.005, 0.01, 0.02 and 0.03wt%) and the HTF mass flow rate on thermal heat transfer coefficient and hence heat flux densities were analyzed. Experimental results show that the average convective heat transfer coefficient increases with increasing the mass flow rate, and it is improved by comparison with the fluid base (distilled water) when the nanofluid is considered. Furthermore, it has been observed that there is an optimal nanoparticles mass concentration corresponding to a maximal average convective heat flux and also a maximal recovered heat flux density. Consequently, convective heat transfer coefficient has a strong influence on the sensible heat during a storage cycle (charging/discharging).

Mechanism of formation of hollow fiber membranes for membrane distillation: 2. Outer coagulation power effect on morphological characteristics

Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) hollow fiber membranes with porous and skinless outer surfaces were prepared for desalination by direct contact membrane distillation (DCMD). N,N-dimethyl acetamide (DMAC)/distilled water mixtures extruded from the outermost channel of the spinneret were employed as external coagulants along the gap of the spinning process. During membrane formation, various types of interactions studied via Hansen solubility parameters were identified at the outer layer of the nascent fiber. Several characterization techniques and DCMD experiments were carried out in order to analyze the effects of the wet gap on the membrane morphology, properties and desalination performance. The skin-layer was avoided and permeate flux was enhanced when using the DMAC/water mixtures as the external coagulants. Increasing the concentration of DMAC in the nonsolvent mixture weakened the external coagulation power and the outer layer morphology of the fiber became more porous with larger surface pore sizes. Open-porous inner surface, skinless outer layer and spongy cross-section were observed for the hollow fiber membranes prepared with the highest amounts of DMAC in water, 50 and 60wt%, used simultaneously as internal and external coagulants. The hollow fiber membrane prepared with the coagulant mixture 50wt% DMAC in water exhibited good mechanical properties and excellent MD membrane characteristics, leading to the highest DCMD permeate flux with a good salt rejection factor.

Ionic Liquid Mediated Biosynthesis of Gold Nanoparticles Using Elaeis Guineensis (Oil Palm) Leaves Extract

This study reports that ionic liquid mediated Elaeis. guineensis (oil palm) leaves extract can be used for reduction of gold precursor to obtain stable gold nanoparticles (AuNPs). E. guineensis leaf extract was prepared by using a mixture of distilled water and 2% aq. ionic liquid (1-Ethyl-3-methylimidazolium chloride) as solvents. UV-vis spectra of reaction medium showed surface plasmon resonance (SPR) peak (λmax) at 539-557nm confirm formation of gold nanoparticles. λmax was blue shifted toward 539nm with increase in volume extract up to 0.60ml while further addition of extract in the reaction medium resulted in red shifting of SPR band. Emim chloride functioned as a capping agent and results in synthesis of small size gold nanoparticles. TEM image analysis confirmed that average particles size of gold nanoparticles was 20.09±12.36nm synthesized with an aqueous solution containing 2% Emim chloride as compared to average particle size of 39.60±13.63nm when only distilled water was used as solvent for extraction of oil palm leaves. FTIR spectra analysis of the extracts identified presence of phenolic, carboxylic and amide groups that play important roles in reduction of gold precursor.

Experimental investigation on the correlation between nano-fluid characteristics and thermal properties of Al2O3 nano-particles dispersed in ethylene glycol–water mixture

This paper presents a multi-parameter investigation of Al2O3 nano-particles dispersed in distilled water, ethylene glycol and ethylene glycol–distilled water mixture (50/50vol.%). The nano-fluid samples were prepared with ultrasonic processing with particle concentration up to 9wt.%. Samples were characterized by transmission electron microscope imaging, particle surface charge (zeta potential), particle aggregate size, light absorbance and pH. The thermal conductivity and viscosity of the nano-fluid samples were measured. 10.9% enhancement in thermal conductivity was observed in ethylene glycol–distilled water mixture based nano-fluid with 5wt.% Al2O3 nano-particle loading. The results show multiple-perspective correlations between nano-fluid characteristics and thermal properties. The findings are summarized as follows. Combined effect of base fluid viscosity and particle surface charge determines the degree of nano-particle aggregation. Higher enhancement in thermal conductivity is observed with moderate particle aggregation, while either light or heavy aggregation lowers the enhancement. The ethylene glycol–water mixture based nano-fluids show overall higher thermal conductivity enhancement than the distilled water and ethylene glycol based nano-fluids. The degradation of nano-fluid thermal conductivity enhancement over time is found to be related to the gravity-driven particle sedimentation. Nano-fluids containing larger particle aggregates show higher viscosity augmentation. However, the extent of viscosity augmentation is not proportional to the extent of particle aggregation.

Thermo-optical properties of copper oxide nanofluids for direct absorption of solar radiation

In this paper, the optical and thermophysical properties of CuO nanofluid as the working fluid of low temperature direct absorption solar collector which is prepared by dispersing the CuO nanoparticles into mixture of distilled water and ethylene glycol (70%:30% in volume) as the base fluid is investigated at the different temperatures for different volume fractions. The results showed that the nanofluids had higher absorption coefficient compared to the base fluid in the whole wavelengths for solar energy, ranging from 200 to 2500nm. The absorbed energy fraction of CuO nanofluid with only 100ppm (volume fraction 0.01%) nanoparticle volume fraction is 4 times more than that of the base fluid at solar collector depth of 1cm. The viscosity increased with the increasing volume fraction and decreased exponentially with the increasing temperature. The thermal conductivity of CuO nanofluids increased with the increase of CuO volume fraction in the base fluid and temperature. At the investigated volume fractions, the thermal conductivity of the nanofluids was found to increase with respect to the base fluid up to about 13.7% for the 100ppm CuO nanoparticle volume fraction. Higher thermal conductivity and lower viscosity of CuO nanofluids by increasing temperature, together with the appropriate optical properties, introduce this kind of nanofluids as an appropriate candidate to effectively enhance the direct absorption solar collector efficiency.

Effects Of Process Parameters On Cu Powder Synthesis Yield And Particle Size In A Wet-Chemical Process

Abstract This study presents a simple wet-chemical process to prepare several micron-size Cu powders. Moreover, changes in powder synthesis yield and particle size are examined with different solvents, synthesis temperatures, and amounts of reducing agent during the synthesis. As a reducing agent and capping agent, L-ascorbic acid and polyvinyl pyrrolidone were used, respectively. The yields in distilled water or an ethylene glycol (EG)/distilled water mixture were higher than that in EG alone, and the yield increased with increasing temperature owing to a lower Δ Gred value. Increasing the L-ascorbic acid concentration also increased the yield. The Cu powder synthesized in 3 h at 90°C in distilled water with 272.8 mM of L-ascorbic acid showed the lowest average particle size of 2.52 μm, indicating mechanisms of short burst nucleation and reduced growth via the increased reduction rate of Cu ions. It is estimated that the nucleation step was nearly completed within 10 min in this system. The Cu powders synthesized in an ethylene glycol/distilled water mixture presented an average particle size of 3.76 μm and the highest yield of 87.9%.

減圧媒体粒子流動層内における微粒子懸濁物質の乾燥特性

Drying characteristics of slurry in a fluidized bed of inert particles （average diameter＝0.12 mm） under reduced pressure were examined. A mixture of distilled water and fly ash （median diameter＝5μm） was used as （model） slurry.To obtain the dry dispersed powder continuously, feed rate of slurry （water flow rate） must be equal to the evaporation rate in the fluidized bed, i.e., the maximum evaporation rate when the water flow rate is equal to the evaporation rate exists. As the powder content in slurry increased, the drying rate became lower. The drying rate was higher as the pressure in the drying chamber decreased, and the temperature in the fluidized bed became lower as the drying rate increased. From these, it was found that the low temperature drying with high drying rate was possible in the fluidized bed of inert particles under the reduced pressure.

EKSTRAKSI PIGMEN ANTOSIANIN DARI KULIT BUAH NAGA MERAH (Hylocereus polyrhizus)

Extraction of anthocyanin pigments from the red pitaya’s peel (Hylocereus polyrhizus) has been done. Anthocyanin pigment from the red pitaya’s peel (Hylocereus polyrhizus) can be used as an alternative for sinthetys dye. Extraction of anthocyanin pigments in this experiment is using maceration method. There are three independent variables used in this experiment, they are the type of solvent (distilled water, 95% ethanol, ethyl acetate and 10% citric acid), solvent ratios (1:2, 1:3 and 1:4,) and the time of extraction process (1, 2 and 3 days). This experiment aims to determine the right type of solvent, better solvent ratio and better extraction time that used to get anthocyanin pigments from red pitaya’s peel. The measurements in this experiment are based on the pH value, the absorbance value and anthocyanin pigment yield. The experimental results shows that the levels of anthocyanin pigments of red pitaya’s peel dissolved in a solvent mixture of distilled water plus 10% citric acid produce the highest level of anthocyanin pigment yield is 62.68% at pH 2 and the extraction time are 3 days.

Liquid chromatography coupled with fluorimetric detection and third derivative synchronous fluorescence spectroscopy as two analytical methods for the simultaneous determination of rabeprazole sodium and domperidone after derivatization with 4-chloro-7-nitrobenzofurazan.

Two simple, sensitive, rapid, economic and validated methods, namely reversed phase liquid chromatography (method Ι) and third derivative synchronous fluorescence spectroscopy (method ΙΙ) have been developed for the simultaneous determination of rabeprazole sodium and domperidone in their laboratory prepared mixture after derivatization with 4-Chloro-7-nitrobenzofurazan. Reversed phase chromatography was conducted using a Zorbax® SB-Phenyl column (250.0 mm × 4.6 mm id) combined with a guard column at ambient temperature with fluorimetric detection at 540 nm after excitation at 483 nm. A mobile phase composed of a mixture of distilled water with methanol and acetonitrile in a ratio of 50:20:30 adjusted pH to 4 has been used at a flow rate of 1 mL/min. Sharp well resolved peaks were obtained for domperidone and rabeprazole sodium with retention times of 5.5 and 6.4 min respectively. While in method ΙΙ, the third-derivative spectra were estimated at 507 and 436 nm for rabeprazole sodium and domperidone respectively. Linearity ranges for rabeprazole sodium and domperidone respectively in both methods were found to be 0.15-2.0 and 0.1-1.5 μg/mL. The proposed methods were successfully applied for the analysis of the two compounds in their binary mixtures, and laboratory prepared tablets. The obtained results were favorably compared with those obtained by the comparison method. Furthermore, detailed validation procedure was also conducted.

Pulsed hydrostatic pressure and ultrasound assisted extraction of soluble matter from mate leaves (Ilex paraguariensis): Experiments and modeling

A set of 47kHz ultrasonic extraction experiments assisted and non-assisted by pulsed hydrostatic pressure was performed in different pressures (91.4, 135.3, 202.9, 270.5, 338.2kPa) at 16.5±2.0°C. A cylindrical extraction vessel fed with a mixture of distilled water and comminute dried leaves was internally equipped with a piston to have either a constant pressure or uniform 1:300 atmospheric and pressurized cycles of extraction per second. Kinetic results of solute mass fraction in the liquid phase determined by gravimetric method were obtained for 25,200s at all the investigated conditions. A pure two-dimensional transient diffusive model was suggested to reproduce the experimental results of ultrasound-assisted extraction at constant pressure. A non-linear increase of the diffusion coefficient with pressure explained the reduction of extraction time by increasing the pressure. The mass transfer from the solid to the bulk liquid phase when involving ultrasonic extraction assisted by pulsed hydrostatic pressure was described by the Fick’s second law with a term to account for internal convection. A positive effect of pressure on velocity in the solid microchannels well-described by a rational function was able to explain the positive influence of hydrostatic pressure pulses on the kinetic results. In both the examined circumstances (only ultrasound or combined ultrasound-hydrostatic pressure pulse) the extraction yield at equilibrium was up to 200% higher than that obtained by conventional infusion at the same temperature.

The hydro-abrasive erosion wear behavior of duplex-treated surfaces of AISI H13 tool steel

The influence of duplex surface treatments consisting of a DC-pulsed plasma nitriding process and subsequent coatings of CrN and TiAlN deposited by physical vapor deposition (PVD) on AISI H13 tool steel was studied in this article. The treated samples were characterized using metallographic techniques, SEM, EDS, and microhardness methods. Hydro-abrasive erosion wear tests were performed in a specifically designed wear tester in which the samples were rotated in a wear tank containing a mixture of distilled water and ceramic abrasive chips with a fixed rotational speed. The wear rates caused by the abrasive particle impacts were assessed based on accumulated weight loss measurements. The worn surfaces were also characterized using optical microscopy, SEM, and EDS. Microhardness measurements indicated a significant increase in the surface hardness of the duplex-treated samples. The surfaces of the samples with the TiAlN coating were approximately 15 times harder than that of the untreated samples and 3 times that of the plasma nitrided samples. Hydro-abrasive erosion wear results showed that the duplex surface treatments, especially the CrN coating, displayed the highest erosion wear resistance.

基于柔性配体5-[N-乙酸根(4-吡啶基)]四唑(a4-pytz)与Fe(II)和Sm(III)两个配合物的合成与表征

5-[N-乙酸根(4-吡啶基)]四唑钾盐(简写为Ka4-pytz)与(NH4)2Fe(SO4)2和SmCl3·6H2O在水-甲醇体系中反应，得到两个新的配合物，[Fe(a4-pytz)2·2H2O]·2H2O (1)和[Sm4(a4-pytz)8(H2O)18]Cl3·10H2O (2)。通过元素分析，红外光谱分析及X-射线单晶衍射对两个配合物进行结构表征。单晶衍射结果显示了配合物1和2都具有一维链状结构。但不同的是，配合物1的一维链是通过a4-pytz作为双齿配体，经四唑环上的氮原子和羧基的一个氧原子与Fe(II)相连而成的；而配合物2的结构形成源于羧基的桥联作用，氮原子未配位。通过氢键作用，配合物1和2形成了三维结构。室温下研究了配合物1和2的荧光性质。 Two new coordination compounds, namely, [Fe(a4-pytz)2·2H2O]·2H2O (1) and [Sm4(a4-pytz)8 (H2O)18]Cl3·10H2O (2) were prepared by reactions of K4-pytz[Ka4-pytz=5-(N-acetato(4-pyridyl)) tetrazole potassium salt] with (NH4)2Fe(SO4)2 or SmCl3·6H2O in a mixture of distilled water and methanol solution. These compounds were characterized by elemental analysis, IR and single crystal X-ray diffraction. The diffraction reveals that both 1 and 2 show 1D chains. In compound 1, a4-pytz acts as a bidentate ligand via its tetrazole-N atom and one of the carboxylate-O atoms while a4-pytz acts as tridentate bridging ligand via the two carboxylate atoms in 2. Compounds 1 and 2 show the 3D networks through hydrogen bonding interactions. Furthermore, the luminescent properties were also investigated at room temperature in the solid state.

Obtaining resistant lettuce progenies to downy mildew

Lettuce is the most consumed leafy vegetable in Brazil. Its production, nonetheless, is increasing in difficulties mainly due to the infestation of producing areas with Bremia lactucae. Thus, the use of horizontal resistant cultivars is the most viable alternative in controlling progress of disease. So, the objective of this study was to obtain resistant lettuce progenies to the races of downy mildew: SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07. The breeding consisted of two stages: crossover of parentals to obtain the resistant lettuce progenies and endurance test of the progeny to B. lactucae races. The parentals used to obtain progenies with resistance factor R-18 and R-38 were: JAB 4-13-7 and JAB 4-13-7. The Pedigree method was used for obtaining the progeny, using as default selections the Hortência cultivar and JAB 4-13-7genotype. After selection and selfing of the plants in the field, the resistance or susceptibility test was realized, by inoculation of the progenies from the crosses, with mixture of distilled water + sporangia of B. lactucae races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07 obtained from isolates collected in the years 2008-2010. Fifteen days after inoculation, the seedlings were selected as resistant or susceptible, discarding those presenting sporulation and necrotic spots caused by B. lactucae. Through the Pedigree method we found 69 progenies F3 with good agronomic characteristics. However, after resistance or susceptibility test, only 19 showed all the plants resistant to downy mildew.

Immunohistochemical localization of transforming growth factor beta 2 and gene expression using real-time PCR in capsaicin-administered rat testis during puberty

The objective of this study was to investigate the effects of capsaicin on the testis distribution of transforming growth factor beta 2 (TGFβ2) and gene expression using real-time PCR in pubescent rats. In this study, rats were divided into 3 groups: capsaicin (CAP), sham, and control. The CAP group was injected with 1 mg/kg doses of capsaicin (10% ethanol and 1% Tween in an 80% distilled water mixture) subcutaneously every day for a period of 1 week. The sham group was injected with a solution of 10% ethanol and 1% Tween in a mixture of 80% distilled water and nothing was injected in control rats. Regarding the histological appearance of testicular sections, the sham and control groups maintained the structure of connective tissue and seminiferous tubule, while in the CAP group, gaps among the tubule cells, invagination in the tubule cell wall, tubular integrity degradation, and breakdowns in the connective tissue were also observed. TGFβ2 immunoreactivity was observed in mature spermatids of all groups; moreover, immunoreactivities in the groups were similar in intensity. These results demonstrate that capsaicin, which is already known to affect gastrointestinal, cardiovascular, and respiratory systems, also interferes with the expression of TGFβ2 in rat testis.

Repeated water absorbency of super-absorbent polymers in agricultural field applications: a simulation study

Super-absorbent polymers (SAPs), a group of new water-saving materials and soil conditioners, have been widely adopted in agriculture, but little is known about their performances in repeated usage and other factors influencing SAPs’ efficiency. Four types of commercial SAPs with organic macromolecules, labeled BF, JP, BJ, and WT, were taken with the aim of determining water-absorption capacity under different conditions, such as distilled water, tap water, soil extraction as the mixture of distilled water and soil, soil extraction as the mixture of tap water and soil, different temperatures, and varying soil drying degrees. After five absorption processes, the repeated water absorbencies in tap water, mixture of distilled water and soil, and mixture of tap water and soil were reduced by 73.4–99.3% relative to those in distilled water. Moreover, water quality had a greater effect on original water absorbency than soil extractions. Water absorbency increased with SAP's concentration, and such increases were reduced with repeated utilization. No significant differences in repeated water absorbency were found with varying temperatures (50, 25, and −4°C). SAPs maintained excellent hydrophilic capacity for an extended period when the drying degrees of hydrogels were less than or equal to 80%. JP was initially considered to best sustain water absorption, followed by WT and BF. BJ showed the least absorption. The performances in repeated usage varied according to absorption stability, gel structure, application concentration of the SAPs, water quality, and soil moisture. Farmers can be recommended to use macromolecules JP and WT to improve crop production under altering dry–wet conditions.

Stability of three commonly compounded extemporaneous enrofloxacin suspensions for oral administration to exotic animals

To evaluate the stability of 3 extemporaneous oral suspensions of enrofloxacin mixed with readily available flavoring vehicles when stored at room temperature (approx 22°C). Evaluation study. 3 commonly compounded oral suspensions of enrofloxacin. On day 0, commercially available enrofloxacin tablets were compounded with a mixture of distilled water and corn syrup (formulation A) or cherry syrup (formulation B) flavoring vehicles to create suspensions with a nominal enrofloxacin concentration of 22.95 mg/mL, and 2.27% enrofloxacin injectable solution was compounded with a liquid sweetener (formulation C) to create a suspension with a nominal enrofloxacin concentration of 11.35 mg/mL. Preparations were stored in amber-colored vials at room temperature for 56 days. For each preparation, the enrofloxacin concentration was evaluated with high-performance liquid chromatography at prespecified intervals during the study. The pH, odor, and consistency for all suspensions were recorded at the start and completion of the study. Relative to the nominal enrofloxacin concentration, the enrofloxacin concentration strength ranged from 95.80% to 100.69% for formulation A, 108.44% to 111.06% for formulation B, and 100.99% to 103.28% for formulation C. A mild pH increase was detected in all 3 suspensions during the study. Results indicated that, when stored in amber-colored vials at room temperature for 56 days, the enrofloxacin concentration strength in all 3 formulations was retained within acceptance criteria of 90% to 110%. Subjectively, cherry syrup flavoring was better at masking the smell and taste of enrofloxacin than were the other mixing vehicles.

Microabrasion on dental restorative porcelains and amalgam

There are a number of different mechanisms by which tooth wear occurs, including tooth–tooth contact, temperature changes and the chemical environment inside the mouth; these different mechanisms can occur simultaneously. ‘Attrition’, ‘abrasion’, ‘abfraction’ and ‘erosion’ are the main terms used to describe tooth wear. Abrasion occurs in the presence of abrasive particles from various sources. Damage by abrasion occurs on enamel or dental porcelain surfaces when particles become trapped in the occlusal zone, a mechanism called three-body wear abrasion. In the current study, three commercial dental powder–liquid porcelains (used as restoratives in posterior teeth) and one amalgam restorative were tested using an in vitro method with a Plint TE66 microwear tester. Wear conditions were 0·25 N of load applied, 0·1 m s−1 of ball speed and 7·98 m of sliding distance at room temperature. Mixtures of distilled water and artificial saliva were used as liquid suspension, each containing 22 vol.-% silicon carbide (SiC F1200), with an average size of 4 μm. Lost volume and wear coefficient of the restoratives were determined. Scanning electron microscopy images were obtained, the wear patterns (scars) on the specimens were analysed and the wear mechanisms (including brittle fractures for the porcelains, and ploughing, cutting and plastic deformation for the amalgam) were identified and discussed. Wear topography was obtained from atomic force microscopy images.

Hydrostatic pressure cycling extraction of soluble matter from mate leaves

The main aim of this study was to investigate the kinetics of solid–liquid extraction of soluble matter from leaves of Ilex paraguariensis assisted by pulsed hydrostatic pressure. A large set of experiments was carried out involving a mixture of distilled water and comminute leaves of mate fed in a batch extractor kept at approximately 16.7°C. The influence of pressure on equilibrium solute concentrations and rate of extraction was examined in the pressure range from 91.4 to 338.2kPa by applying or not hydrostatic pressure cycles. Whatever the case a significant increase of such responses with direct positive impact on extraction yield and time of extraction was experimentally observed by changing the investigated factor (e.g.; the extraction yield was increased from ≈13% at 91.4kPa to approximately 34% and the time to have 90% of the highest efficiency was reduced from ≈17,000s at 91.4kPa to ≈6000s by applying hydrostatic pressure pulses at only 338.2kPa). An hybrid diffusive–convective model was suggested to represent the transient extraction of soluble compounds from the discoid particles. The classical Fick’s law described the two-dimensional diffusion for the static long periods of mass transfer at constant pressure, while a model dependent on the gamma function computed the fraction of solute periodically extracted by convection from the internal solid microchannels during the rapid pulses of hydrostatic decompression. For all the investigated conditions the proposed analytical model well reproduced the kinetic experimental results of solute mass fraction in the solid and liquid phase.