Solvent evaporation

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Development of pH-sensitive polymeric nanoparticles for targeted drug delivery to the ischemic heart

Development of pH-sensitive polymeric nanoparticles for targeted drug delivery to the ischemic heart

Heart failure post-myocardial infarction remains one of the global leading causes of mortality. The therapeutics, available today, only ameliorate the symptoms, without having any preventive effect on the, functional and structural, heart-remodeling process that ensues after such ischemic event. For this, lately, nanotechnology has emerged as a possible alternative to overcome countless limitations of conventional cardiovascular medicine. The present study focus on the preparation of nanoparticles with resort to the emulsification and solvent evaporation method, using the spermine-modified acetalated dextran as polymer for selective drug delivery of a cardioprotective drug. Additionally, it dwells on the subsequent functionalization resorting to crosslinking chemistry and using propylene glycol as a bioconjugate, given its hydrophilic properties and ability to prolong the nanoparticles’ plasma half-life. The process and formulation variables, explored in this investigation, whether on preparation or functionalization, revealed to be of crucial importance to the nanosystem’s characteristics. The optimization, on propylene glycol conjugation, was not possible, for the drug-loaded nanoparticles, within the time frame set for the experimental work. Upon PEGylation, major improvements were verified in colloidal stability (assessed in cell culture medium) and cytocompatibility (assessed in rat myoblasts). The drug release did not follow the pH-sensitive solubility pattern of the polymer, that is, with burst release in acidic conditions and sustained release in neutral pH. Several points to take in consideration and suggestions, for future work, are presented on how to refine this platform for intracellular nanodelivery.
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J. Braz. Chem. Soc.  vol.19 número7

J. Braz. Chem. Soc. vol.19 número7

for these microparticles can be justified by a substantial migration of the drug from the primary emulsion to the external aqueous phase during the emulsification and/or solvent evaporation procedures. Comparing EE for M1, M2 and M3 it can be noted that the lower the drug concentration in the organic phase was, the higher the EE value was. To circumvent the low EE values obtained for M1 to M3, other formulations were prepared by the double emulsion/solvent evaporation technique as summarized in Table 2.

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Menthol-loaded PLGA Micro and Nanospheres: Synthesis, Characterization and Degradation in Artificial Saliva

Menthol-loaded PLGA Micro and Nanospheres: Synthesis, Characterization and Degradation in Artificial Saliva

Menthol-loaded PLGA micro/nanospheres were synthesized using the multiple emulsion/solvent evaporation technique. Parameters such as stirring rate, external surfactant content, PLGA/menthol weight ratio, solvent evaporation and lyophilization time were evaluated as well as the degradation of micro/nanospheres in an artificial saliva medium. The menthol/PLGA micro/nanospheres thus obtained had a size distribution of between 217 nm and 13 µm and particles with spherical and dense morphology were evidenced by SEM micrographs. FTIR and TGA data showed an increase up to 60% of menthol incorporated in the micro/nanoparticles. The degradation of menthol-loaded PLGA micro/nanoparticles in artificial saliva significantly affected the particles morphology and appears to be an effective medium for releasing menthol.
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Rev. Bras. Cienc. Farm.  vol.43 número4

Rev. Bras. Cienc. Farm. vol.43 número4

Microparticulate systems of nimesulide (NIM) were prepared by modified solvent evaporation method using different variables such as polymer: drug (NIM) ratios (cellulose acetate, CA: nimesulide, NIM) (1:9, 1:6 and 1:3), agitation speeds (500-1500 rpm) and stirring time (15-30 min). The effects of processing variables were evaluated by microparticle size and entrapment efficiency. The average microparticle size increases from 66.8±1.45 to 87.3±1.06 µm with increase in the polymer concentration while reduces with increase in agitation speed and stirring time; but at the too higher speed gives irregular shape of particles. The highest entrapment efficiency (77.83±0.51%), size uniformity, free flowability, i.e., angle of repose (23.5±0.4º) and compressibility index (14.2±0.6%), of microparticles were found with 1:6 (polymer: drug ratio), at 1000 rpm and 20 min stirring time among all prepared microparticles (P ≤ 0.05). The in-vitro drug release study of microparticles with optimized processing variables (agitation speed and time) were carried out and compared with conventional and marketed SR tablets. The conventional tablet releases maximum drug within 4 h while microparticulate system releases more than 14 h. All formulations followed first order release kinetic and diffusion controlled drug release (Higuchi model). These microparticles are stable at room temperature (25±1 °C) but agglomerate at elevated temperature (50±1 °C) by softening and fusion of the polymer observed under SEM study.
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Caracterização de nanopartículas blenda poliméricas biodegradáveis contendo progesterona Fernanda Vitória LeimannI Maiara Heloisa Biz

Caracterização de nanopartículas blenda poliméricas biodegradáveis contendo progesterona Fernanda Vitória LeimannI Maiara Heloisa Biz

The z-average size (Dz) and polydispersion index (PDI) of the nanoparticles containing progesterone are presented in table 1. All formulations yielded particles in the nanometric range. Also, low polydispersity indexes were found with no significant difference (P>0.05). BYUN et al. (2011) prepared α-tocopherol-loaded PCL nanoparticles by emulsion solvent evaporation using a sonication apparatus. The average nanoparticles size obtained by the authors remained between 247 and 1070nm using poly (vinil alcohol) as surfactant. MUSYANOVYCH et al. (2008) produced PCL nanoparticles with lutensol as surfactant and obtained similar results as those presented in table 1.
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PREPARATION AND IN-VITRO EVALUATION OF BACLOFEN LOADED MICROSPHERES

PREPARATION AND IN-VITRO EVALUATION OF BACLOFEN LOADED MICROSPHERES

The present study was aimed to prepare Baclofen microspheres for sustained release using various polymers such as ethyl cellulose (hydrophobic), hydroxy propyl methyl cellulose (hydrophilic) by employing solvent evaporation technique. Drug and excipients compatibility was studied by Fourier Transform Infrared Spectroscopy and no incompatibility was observed. The obtained microspheres were evaluated for the percent drug content, entrapment efficiency and in-vitro dissolution studies. The entrapment efficiency of the obtained formulations was in between 66-88% and in-vitro release of F7 formulation showed 93% in 24 hrs. Scanning Electron Microscopy, Differential Scanning Calorimetry and X-Ray Diffraction studies were performed for F7 formulation. From the results Scanning Electron Microscopy of reveals that microspheres was found in spherical and porous nature. X-Ray Diffraction studies results showed baclofen was in amorphous form which was further confirmed by Differential Scanning Calorimetry. The curve fitting data revealed that the release of obtained formulations follows mixed order kinetics with non‐fickian type of drug release (anomalous).
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Microencapsulation of a Colombian Spodoptera frugiperda Nucleopolyhedrovirus with Eudragit® S100 by Spray Drying

Microencapsulation of a Colombian Spodoptera frugiperda Nucleopolyhedrovirus with Eudragit® S100 by Spray Drying

Pareto diagram (Fig.1D) showed that polymer- polymer interaction and polymer concentration (B) were again the only factors that had a significant effect on particle size; thus leading to the conclusion that when polymer concentration was increased, the percentage of desired size microparticles was also increased. In some treatments, independent spherical particles were observed (results not shown), but in other treatments, big aggregates were produced, possibly due to coalescence of drops during the drying process. Some microparticles showed cavities or holes that could be attributed to the contraction generated by particle formation during the drying process due to rapid solvent evaporation (Fritzen-Freire et al. 2012).
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Braz. J. Pharm. Sci.  vol.52 número4

Braz. J. Pharm. Sci. vol.52 número4

In our study, we used HSPs approach as a tool to predict the miscibility of cocrystal former and acyclovir. Selection of coformer was performed based on the prediction of HSPs. Cocrystals of acyclovir with improved solubility were developed using solvent evaporation method using water as a solvent. The ratio of drug to that of coformer was optimized by considering the number of theoretical hydrogen bond donor sites and hydrogen bond acceptor sites in acyclovir and cocrystal formers. The solid analysis was performed using Melting Point, Microscopic evaluation, IR, DSC and PXRD techniques. In vitro dissolution, assay was performed to check the dissolution of cocrystal initially. The study suggested the initial solubility of cocrystals was considerable higher as compared to pure drug. Hence synthesis of cocrystals of acyclovir can be considered as a promising approach for increasing the solubility.
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Dissertação para obtenção do Grau de Doutor em Química Orientador: Professora Doutora Maria Teresa Barros, Professor Associado com Agregação, FCT-UNL

Dissertação para obtenção do Grau de Doutor em Química Orientador: Professora Doutora Maria Teresa Barros, Professor Associado com Agregação, FCT-UNL

were successfully synthesized (Table 10). The PNPs prepared by nanoprecipitation were smaller in size and with a low polydispersity index than those prepared by the emulsion-solvent evaporation method. When the emulsion was formulated by sonication smaller particles were obtained, in contrast to that obtained by vortex mixing. However, it is known, that longer exposure times to sonication can produce surfactant degradation by radicals which form during the thermal decomposition of water. The utilization of PVA as colloidal stabilizer resulted in ζ-potential close to zero, while the surfactant-free nanoprecipitation method resulted in negative ζ-potentials, with the Suc-PEG2000-Chol 17 formulation having the highest value, which indicates a stable colloidal suspension. From this results and due to the difficulty in generating a monodisperse emulsion, the nanoprecipitation technique proved to be the best method to prepare PNPs with a narrow particle size distribution. Nevertheless, as the purification step by centrifugation failed for this type of PNPs, the dialysis method could be an attractive alternative. Surfactants are not necessary for the preparation of PEGylated PNPs, as PEG is able to stabilize the colloidal system through steric interactions. Although, surfactants do improve the resuspension of particles after lyophilization and it is well known that production of non-aggregated nanoparticles is just the first step for drug delivery. Alternatively, vitamin E TPGS could also function as an effective stabilizer for synthesizing PNPs. It is amphipathic, less hydrophilic than PVA and have the ability to enhance absorption through the intestinal wall. 136
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Braz. J. Pharm. Sci.  vol.45 número3

Braz. J. Pharm. Sci. vol.45 número3

The objectives of our study were to prepare and evaluate a biodegradable nanoparticulate system of Letrozole (LTZ) intended for breast cancer therapy. LTZ loaded poly(lactide-co-glycolide) nanoparticles (LTZ-PLGA-NPs) were prepared by emulsion-solvent evaporation method using methylene chloride and polyvinyl alcohol. Percentage of drug (with respect to polymer) was selected as formulation variable. LTZ-PLGA-NPs were characterized by particle size, zeta potential, infrared spectra, drug entrapment eficiency and in vitro release. Sonication was done with an ultrasound pulse sonicator at 70 W, 30 kHz for 90 sec to produce stable NPs of mean size range from 64 nm to 255 nm with high entrapment eficiency (68% to 82%). Percentage of drug signiicantly inluenced particle size, entrapment eficiency and release (p <0.05). The system sustained release of LTZ signiicantly and further investigation could exhibit its potential usefulness in breast cancer therapy.
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Eclet. Quím.  vol.35 número1

Eclet. Quím. vol.35 número1

As it evident from the table, with the increase in solvent, total eficiency is also increased, ho- wever, because the NMP solubility in n-heptane is constant at set temperature, by the reduction in tem- perature, the NMP rich phase is reduced, therefore, the more solvent is used the more NMP remains in solvent thus reduces NMP weight percent which is our goal. However, at higher solvent-residue ratio, this process renders ineficient with an intangible reduction in total eficiency and NMP weight percent. Therefore, a 6:1 solvent ratio seems to be optimum, and since this ratio tends to hold the highest ac- ceptable total eficiency, and since the separation of NMP and n-heptane both having two very different boiling points, this method could save large amount of very valuable solvent.
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J. Braz. Chem. Soc.  vol.26 número6

J. Braz. Chem. Soc. vol.26 número6

A new, simple, rapid and efficient solvent terminated-auxiliary solvent-dispersive liquid-liquid microextraction (ST-AS-DLLME) technique for determination of cyanide ions by microvolume UV-Vis spectrophotometry was developed. Effective parameters on the extraction and absorbance of cyanide were optimized using two optimization methods: fractional factorial design (FFD) and central composite design (CCD). Zinc(II) tetraphenylporphyrine (ZnTPP) was used as a selective cyanide receptor agent. Methyl isobutyl ketone (MIBK), ethanol and 1-butanol were used as extraction solvent, dispersive solvent and demulsifier solvent, respectively. The method shows very good selectivity in presence of other species. The analytical curve was linear in the range of 4.0-130 µg L -1 with a limit of detection of 1.0 µg L -1 . Relative standard deviation (RSD)
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Stem–root flow effect on soil–atmosphere interactions and uncertainty  assessments

Stem–root flow effect on soil–atmosphere interactions and uncertainty assessments

wilting point. The stomatal resistance that controls transpi- ration is very sensitive to the soil moisture near the wilting point. As such, a slight decrease in the moisture of the top soil layer can dramatically reduce transpiration. When soil moisture approached the wilting point in late July, plant tran- spiration reduced sharply in response to the stem–root flow effect (red curve in Fig. 8a). Such a change in plant transpi- ration caused an increase in the air temperature near the soil surface (magenta curve in Fig. 8b) and a decrease in air hu- midity, which increased soil evaporation (blue curve in Fig 8a). In early August, however, soil moisture accumulated in the bottom layer through the stem–root flow (cf. Fig. 6c) and the stomatal resistance began to decrease such that transpi- ration recovered and soon dominated the overall evapotran- spiration throughout the rest of the growing season. The in- creased transpiration also caused a reduction in air temper- ature and surface temperature and thus the associated sensi- ble heat flux (blue curve in Fig. 8b). During late August to mid-September, surface soil moisture was so low in some in-
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Test of a microlysimeter for measurement of soil evaporation

Test of a microlysimeter for measurement of soil evaporation

LEMON (1956), working under laboratory conditions, divided the process of evaporation of water from bare soil in three distinct phases, later proven in the field by IDSO et al. (1974). The first phase is characterized for presenting potential evaporation rate and is dependent only on the conditions prevailing in the atmosphere near the ground. This phase is independent of soil moisture conditions under the assumption that there is no restriction on the upward flow of water in the profile. The first phase ends when is established resistance to the water flow toward the soil surface and the evaporation rate is no longer potential, decreasing with time. In the second phase, the intrinsic soil conditions limit the transport of water in the profile and hence the evaporation rate. Thus, in this phase LEMON (1956) considers that the evaporation rate decreases linearly with the decrease in average moisture of the soil profile and atmospheric conditions are no longer of importance. When the variation of evaporation in response to the decrease of soil moisture becomes very small, losing linearity, the third phase begins. This phase is characterized by a rather slow movement of water toward the surface, due to low hydraulic conductivity of the soil.
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Braz. J. Pharm. Sci.  vol.48 número4

Braz. J. Pharm. Sci. vol.48 número4

Naproxen, an anti-inlammatory drug, exhibits poor aqueous solubility, which limits the pharmacological effects. The present work was carried out to study the effect of agglomeration on micromeritic properties and dissolution. Naproxen agglomerates were prepared by using a three solvents system composed of acetone (good solvent), water (non-solvent) and dichloromethane (bridging liquid). Differential Scanning Calorimetry (DSC) results showed no change in the drug after crystallization process. X-Ray Powder Diffraction (XRPD) studies showed the sharp peaks are present in the diffractograms of spherical agglomerates with minor reduction in height of the peaks. The residual solvents are largely below the tolerated limits in the agglomerates. Scanning Electronic Microscopy (SEM) studies showed that agglomerates were spherical in structure and formed by cluster of small crystals. The agglomerates exhibited improved solubility, dissolution rate and micromeritic properties compared to pure drug. Anti-inlammatory studies were conducted in Wistar strain male albino rats and naproxen agglomerates showed more signiicant activity than the pure drug.
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Evaporation of a binary liquid film by forced convection

Evaporation of a binary liquid film by forced convection

are obtained in forced convection, particularly in the case of ethylene glycol-water mixture. In fact, the obtained results have shown that it is possible to increase the accumulated evaporation rate when the molar fraction of ethylene glycol is less than 40%. Palen et al. [3] studied experimentally the evaporation of a liquid mixture; ethylene glycol-water inside a vertical tube of circular section. They observed that for some experimental conditions, the local heat transfer coefficient between the gas and the liquid mixture can fall of 80% in relation to the relative value to the pure water, value that is lower to the one gotten with the pure ethylene glycol in the same conditions. Hoke et al. [4] presented a numerical study of the evaporation of a binary liquid film on a vertical plate. They showed that the value of the Sherwood number was roughly two times the value of the Nusselt number for the case of heat transfer if the experimental conditions are reversed. It was shown that the influence of the evaporation on the Sherwood number was especially weak for constant debits of the considered constituent. Vijay et al. [5] presented a study of the isotherm evaporation of a binary liquid film. They could measure the diffusion coefficient during the evaporation of a binary liquid in a Stefan tube while observing the position of the liquid-gas interface. Baumann et al. [6] studied the heat and mass transfer in evaporating two component (benzene-methanol) liquid film flow. For the two-phase multicomponent flow in two-compo- nent liquid film evaporation a physical model has been proposed. The prediction for the evaporation of benzene-methanol mixtures in a hot tubular air stream clearly shows the influence of the phase equilibrium and its interaction with the local transport processes. El Armouzi et al. [7, 8] investigated numerically the evaporation by mixed convection of a binary liquid film flowing down of two coaxial cylinders. They showed that the volatilities of the mixture influenced the heat transferred through the latent mode, which is more pronounced for mixture composed of volatile components. They also showed that the mass and heat transfers were more important near the inlet of the channel and increased with the wall heat flux density. For the same inlet air velocity, the concentration and the liquid film thickness were the critical parameters, which governed the transfers during its evaporation.
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COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

COBALT SALTS PRODUCTION BY USING SOLVENT EXTRACTION

The possibility of carrying out the method of cation-exchange solvent extraction conversion in continuous regime was tested at a laboratory cascade, when cobalt was extracted from a chloride solution of the following composition, g/l: Co – 112; Ni – 0.01; Fe, Mn, Cu <0.005 with ammonium form of n-octanoic acid in Escaid 100 at four stages followed by a two-stage re-extraction with a 2 mole/l vinegar acid solution. The pattern of the experiment on the production of cobalt acetate solution at an extractor cascade with ammonium form of n-octanoic acid is presented in Fig. 3.

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Flow regime change in an Endorheic basin in Southern Ethiopia

Flow regime change in an Endorheic basin in Southern Ethiopia

oration (AET) and potential evaporation (PET), and to understand if these reflect the trends found in the temperature data. Although this data has not been validated against observed data in the basin due to the lack of measurements from for example flux tow- ers (Trambauer et al., 2013), it can be applied for detecting trends. We investigate the presence of trends in the five homogenous regions and downstream un-gauged region

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Quím. Nova  vol.33 número10

Quím. Nova vol.33 número10

speciic and is, therefore, independent of probe-structure. A more fundamental reason for the non ideal solvation behavior is, however, solvent micro-heterogeneity, i.e., where one component of the mixed solvent prefers a molecule of the same type. A large body of experi- mental data and theoretical calculations, e.g., of the Kirkwood-Buff integral functions (that describe W-W, S-S, and S-W interactions), has shown that many binary mixtures are micro-heterogeneous;

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Exploring the Anticancer Activity of Grape Seed Extract on Skin Cancer Cell Lines A431

Exploring the Anticancer Activity of Grape Seed Extract on Skin Cancer Cell Lines A431

In this study, grape seeds were extracted using ethyl acetate and petroleum ether by solvent-solvent extraction method. The phytochemical tests were performed to identify different phytochemical compounds present in the grape seed extract (GSE). Antibacterial activity of the GSE was determined using agar diffusion method against Gram- positive and Gram-negative bacteria. Gas chromatography –mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR) analysis was done to identify the presence of bioactive compounds and their functional groups. The GC-MS results revealed a total of four compounds, known to have potent activity against cancer cells, viz, squalene, the most potent compound found in ethyl acetate extract and diethyl phthalate, ethyl-9- cis -11- trans octadecadienoate and (R)-(-)-14,-methyl-8-Hexadecyn-1-ol in petroleum ether extract. Cytotoxic activity of the GSE was observed against skin cancer cell lines A4321 using 3-(4, 5-dimethylthiazol-2-yl)-2-5- diphenyl tetrazolium bromide) MTT assay. The IC 50 value of the GSE against A431 skin cancer cell line was 480
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