Residual Humidity Research Articles

Investigation of in situ annealing on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate): towards all-solution-processed inverted polymer solar cells

Efficient spray-coated inverted polymer solar cells (PSCs) based on a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer (HTL) are investigated by incorporating an in situ annealing treatment. Compared to conventional annealed devices, the in situ annealed PSCs exhibited a 25.5% and 47.7% enhancement in fill factor and power conversion efficiency (PCE) respectively, as well as about a two-fold improvement in the device lifetime. The performance enhancement was attributed to the improvement of the vertical phase separation of the PEDOT:PSS HTL and the reduction of the residual humidity of the HTL. This approach significantly enhances our understanding of the application of the PEDOT:PSS HTL in inverted PSCs, and illuminates the potential of spray coating for the sustainable commercial fabrication of PSCs with high PCEs.

Experimental Studies of Excess Noise Sources in Concrete Based Materials as a Limiting Factor for Electromagnetic Emission Measurement

This paper deals with excess noise sources in dielectric materials. We focus especially on the concrete samples that are frequently tested to ensure information about the reliability and level of degradation. Nevertheless, the testing methods are limited mainly by the proper contact creation, signal detection and noise defined sensitivity. Our efforts are directed to the noise properties assessment. It turns out that the Johnson-Nyquist noise and the 1/f (flicker) noise are generated in the different regions with the different response to the internal or external electric field. In addition the noise analysis is affected by the internal polarization phenomena and the material residual humidity. This issue in connection with the sample geometrical properties and the dielectric noise measurement methodology take part in this paper.

Influence of Microstructure, Environment and Temperature on Fatigue Crack Propagation in 2XXX Aluminium Alloys

Aluminum alloys, widely used for constitutive parts of aircrafts are confronted to a wide range of temperature depending on altitude and climate, from room temperature on the ground down to some 223K at high altitude. The fatigue crack growth behavior of two new generation aluminum alloys, 2024A in T351 temper and 2022 in T351 and T851 tempers, have been investigated at both temperatures. It is shown that temperature and air humidity do not affect the crack growth resistance of the peak aged 2022 while these two parameters widely influence the crack growth in the under-aged alloys which exhibit in cold air a crystallographic retarded propagation similar to that in vacuum. The respective role of microstructure, temperature, atmosphere residual humidity and crack closure is discussed on the basis of a preexisting modeling framework for environmentally assisted fatigue.

Encapsulation of a pressure sensitive adhesive by spray-cooling: Optimum formulation and processing conditions

An industrial pressure sensitive adhesive (PSA) was encapsulated by spray-cooling using hydrogenated palm oil. A screening design methodology was used to evaluate the impact of some formulation and process variables on the particle properties. Six operating factors were retained and the results considered were the production yield, the particle volume-surface average diameter D32, the residual humidity, the ratio of the fusion enthalpies of the polymorphs α and β′/β and the normalized peeling force. The statistical analysis of the results showed a negligible impact of the parameters related to the process. The heating temperature, the PSA and surfactant ratios were the most significant factors. It was possible to produce spherical particles with a mean size of 17.7μm and a normalized peeling force of 0.218Nm2/g. The production yield was 70%. A duplicate test confirmed the results. Mechanical tests on unitary particles showed an increase of the rupture and adhesion forces with particle size.

Polyvinylpyrrolidone–LiClO4 solid polymer electrolyte and its application in transparent thin film supercapacitors

Films of PVP (polyvinylpyrrolidone) and LiClO4 have been obtained by dip coating to be used as solid ionic conductors in transparent energy storage systems. The dependence of the ionic conductivity of PVP/LiClO4 films on temperature, lithium salt concentration, and residual solvent content or humidity has been studied. The films were used in a symmetrical supercapacitor (PEDOT/PVP/PEDOT). Whose behaviour with the aging time was analysed as well. It was observed that the experimental differences in the performance of a lithium ion based energy storage devices using these films as solid electrolyte may be due to changes in the residual content of the solvent used in their preparation or the hygroscopic nature of the electrolyte.

Investigation on formulation and preparation of adenovirus encoding human endostatin lyophilized powders

A recombinant adenovirus encoding human endostatin gene, E10A, has finished phase II trials for head and neck cancer. However, the rigid storage temperature (−80°C) and the toxicity of glycerol in the E10A liquid preparation limited its clinical application. In this study, lyophilization was applied to develop a stable E10A lyophilized powder without glycerol that is able to maintain biological activity at 4°C and suitable for intravenous administration. The E10A lyophilized formulations composed of nontoxic and already clinically used excipients were characterized in terms of the pH change during freezing, the eutectic melting temperature (Teu) and the collapse temperature (Tc). Freeze thawing tests were carried out to examine the protective effect of various excipients during freezing. Mannitol and its combinations with sucrose or inulin showed effective protection of E10A. The E10A lyophilized powders were analyzed by particle size measurement, residual humidity quantification, infectivity assay and gene expression level. An optimized formulation (formulation I1) yielded a good recovery of 76% of the starting infectivity after lyophilization and 89% of the original infectivity after storage at 4°C for 180 days. Also the gene expression capability of E10A in formulation I1 was maintained after lyophilization. In addition, it was found that the matrix of amorphous excipients, mannitol combinations with sucrose or inulin, was indispensible in protecting E10A against the stress of freezing and dehydration. Hereby, the E10A lyophilized powder with eliminated glycerol toxicity and improved stability could enhance the applicability of E10A for cancer gene therapy through intravenous administration.

Micronization of polyethylene glycol by PGSS (Particles from Gas Saturated Solutions)-drying of aqueous solutions

Micronization of polyethylene glycol from aqueous solutions has been successfully performed with a Particles from Gas Saturated Solutions (PGSS)-drying process, producing spherical PEG particles with average particle size of 10μm and residual water content below 1wt%. A detailed experimental analysis of the influence of different process and design parameters (temperature, pressure, flow rates, design of the static mixer used to put into contact aqueous solution and CO2) has been carried out. Smaller particles were obtained when carbon dioxide/solution ratio, pressure and temperature were increased. The residual humidity in the product decreased when carbon dioxide/solution ratio and temperature were increased and when pressure was decreased.

Monitoring forest soil properties with electrical resistivity

Maintenance and monitoring of soil fertility is a key issue for sustainable forest management. Vital ecosystem processes may be affected by management practices which change the physical, chemical and biological properties of the soil. This study is the first in Europe to use electrical resistivity (ER) as a non-invasive method to rapidly determine forest soil properties in the field in a monitoring purpose. We explored the correlations between ER and forest soil properties on two permanent plots of the French long-term forest ecosystem-monitoring network (International Cooperative Program Forests, Level II). We used ER measurements to determine soil-sampling locations and define sampling design. Soil cores were taken in the A horizon and analysed for pH, bulk density, residual humidity, texture, organic matter content and nutrients. Our results showed high variability within the studied plots, both in ER and analysed soil properties. We found significant correlations between ER and soil properties, notably cation exchange capacity, soil humidity and texture, even though the magnitude of the correlations was modest. Despite these levels of correlations, we were able to assess variations in soil properties without having to chemically analyse numerous samples. The sampling design based on an ER survey allowed us to map basic soil properties with a small number of samples.

Experimental Study and Modeling of Freeze-Drying in Syringe Configuration. Part I: Freezing Step

This article concerns the experimental study and the modeling of the freezing step during freeze-drying of a model lyoprotectant formulation in syringe configuration. First, ice crystal morphology observations were carried out in a cold chamber equipped with stereomicroscopy to determine the ice crystal size distribution. We observed that the ice crystal morphology was homogeneous as a function of the radial position and that, contrary to our previous observations in glass vial configuration, no significant ice morphology differences existed between the bottom and the top of syringes. Thus, it seems that the gas cooling by free convection at the walls of the syringe during the freezing step led to higher homogeneity in the ice crystal morphology. These data allowed calculation of the mean ice crystal diameter (which was supposed to represent the mean porous diameter) and then the permeability of the freeze-dried cake. Moreover, a two-dimensional axisymmetric (2D) mathematical model in cylindrical geometry of the freezing step for aqueous sucrose solution was elaborated. It has been proved that this model was able to simulate quite precisely the whole temperature profiles during the freezing step, except the exothermic peak of nucleation. In the last part of this work on syringe geometry, the impact of annealing treatments on the freeze-dried matrix morphology was investigated. Some heterogeneity of sublimation rates was observed, with significant variation of residual humidity. Additionally, the water vapor mass transfer resistance values decreased if a convenient annealing treatment (shelf temperature at −10°C) was applied.

Physical characteristics and aerosol performance of naringin dry powders for pulmonary delivery prepared by spray-drying

The aim of the present work was to develop dry powders containing naringin for a direct administration to the lung to combat oxidative stress. Naringin microparticles were prepared by spray-drying the neat flavonoid (2–5% w/v) from different water/ethanol co-solvents. The spray-dried powders were characterised for morphology, density, particle size distribution, residual humidity, crystallinity, solubility, thermal behaviour and respirable fraction. The fine fraction of the powders was measured by single-stage glass impinger and Andersen cascade impactor, using the Turbospin ® device for the deposition tests, wherein the dose to be aerosolised was premetered in a gelatine capsule. By increasing the ethanol content, the feed liquid turned from a suspension into a solution: the spray of flavonoid suspensions led to powders with high crystallinity degree, low water solubility and high bulk density, while the spray of drug solutions led to more amorphous particles, with higher solubility, lower density and improved aerodynamic behaviour. The optimisation of the operative parameters produced enhanced aerosol performance of the flavonoid powders containing only the active compound.

Tomate longa vida desidratado em diferentes temperaturas de secagem

The demand for the consumption of dried tomatoes has grown in recent years, especially under the justification that tomatoes contain allegedly healthy bioactive substances. The research aimed to evaluate three drying conditions (80ºC; 100ºC; 100ºC for 3h followed by 80ºC) applied to cv. Carmem long-life tomatoes in order to obtain a dehydrated product with a projected residual humidity of 60% in weight. A small-capacity dryer was used, equipped with forcedair circulation and five trays. The fresh tomatoes, both sliced and whole, yielded 12.2-13.6% and 7.5-8.5% in weight of dehydrated product, respectively. The treatment consisting in the application of a temperature of 100ºC for 3h followed by 80ºC for 4h and 24min, with the door of the dryer closed, resulted in a dehydrated product with good appearance and without any burned slices; therefore, it was recommended for drying cv. Carmem long-life tomato slices.

Extraction of green tea and drying with a high pressure spray process

Green tea is a beverage widely consumed throughout the world and is produced from non-fermented leaves of Camellia Sinensis. Traditionally, green tea leaves are extracted with water. To form solid products, these aqueous products have to be dried. The main focus of the investigation is how to avoid antioxidant degradation during solvent removal. The work was separated in two major sections, firstly investigation of the extraction process secondly, optimizing of the drying process. In the first experiments extractions with different solvents (H2O, EtOH and MeOH), at different temperatures (20, 40, 60 and 80 ?C) and extraction times (15, 30, 60, 90 and 120 min) were preformed to obtain optimum conditions for further processing. For further work extracts obtained with water extraction at 80?C for 15 min were used. In the PGSS (Particles from Gas Saturated Solutions) drying process, extracts with up to 98 wt % water are mixed with preheated carbon dioxide in a static mixer in order to obtain a homogenous mixture. The mixture is led via a single path nozzle into a spray tower. Driven by the expansion of the gas, fine droplets are formed and the heated gas evaporates the solvent, which is exhausted together with CO^ by a blower. Fine powder is formed and collected in the spray tower. The amount of solvent which is to be removed and the residual humidity obtained in the product depend strongly on flow rate and temperature of the gas. From obtained results it can be seen, that high pre-expansion temperatures Tp (145 ?C) cause degradation of polyphenols (1.05 wt %). Maintaining Tp at approximately 130 ?C and lower gave satisfying results; total amount of polyphenols in the obtained powders was between 4.97 and 8.77 wt %. Temperature in spray tower ranging from 33 to 65 ?C has no significant effect on the amount of total polyphenols, but higher temperature results in lower water residue in the sample.

Detection of Corrosion Damage on Pressure Equipment with Acoustic Emission

Acoustic emission testing (AT) is in Europe an already well established non-destructive testing (NDT) method. Qualification requirements as well as certification of testing personnel are laid down in European standard EN 473. A widespread application of AT deals with testing of unfired pressure vessels for re-qualification after a certain period of service (repetition test). The advantages of applying AT compared to the traditional procedure of hydrostatic test plus visual inside inspection are numerous. Just to name the most important: reduction of downtime, omitting of residual humidity and no risk of product contamination with water. It is a fact that AT provides much more useful information concerning the condition of the pressure vessel under test than a simple ‘passed’ or ‘not passed’ obtained usually by a hydrostatic test. This contribution gives two examples of practical experience, where severe corrosion defects have been detected by AT. The defects have been found in both cases on the vessel’s shell under the thermal insulation, where they have been hidden undetected for years. It can be assumed that even the vessel with the most severe damage (loss of more than 50% of the nominal wall thickness) would have passed the traditional repetition test procedure and that failure within the following service period would have occurred. In contrary to this scenario, AT enabled the vessel operator to perform appropriate repair in time.

A pilot study of freeze drying of poly(epsilon-caprolactone) nanocapsules stabilized by poly(vinyl alcohol): Formulation and process optimization

A common limitation of using polymeric nanoparticles in aqueous suspension is due to their poor chemical and physical stability when conserved for a long time. Therefore, freeze drying of these colloidal systems is an alternative method to achieve long-term stability. Nanocapsules have thin and fragile shell structure, which may not resist to the stress of such process. The aim of this study is to investigate the formulation and process parameters in order to ensure the stability of polycaprolactone nanocapsules (PCL NC) by freeze drying. In this paper, we studied the freeze drying of PCL NC prepared by the emulsion–diffusion method and stabilized by poly(vinyl alcohol) (PVA). Different parameters have been tested throughout the freeze–thawing study including PVA and PCL concentration, cooling rate, cryoprotectant concentrations, nature of encapsulated oil and NC purification. On the other hand, nanocapsules have been freeze dried both before and after purification. Freeze dried purified PCL NC were characterized by particle size measurement, collapse temperature, T ′ g determination, scanning electron microscope observation, environmental scanning electron microscope imaging and residual humidity quantification. Finally, the effect of annealing on the NC stability and the sublimation rate has been well explored. The results suggest that PCL NC could be freeze dried without a cryoprotectant if the concentration of PVA stabilizer is sufficient (5%), while for the purified NC the addition of 5% of cryoprotectant seems to be necessary to ensure the stability of NC. The type of cryoprotectants had practically negligible effects on the size and the rehydration of freeze dried nanocapsules. The annealing process could accelerate the sublimation with the conservation of nanocapsules size.

Influência da temperatura de secagem e da concentração de Aerosil®200 nas características dos extratos secos por aspersão da Schinus terebinthifolius Raddi (Anacardiaceae)

A Schinus terebinthifolius Raddi é muito usada na medicina popular e atualmente como fitomedicamento pelas propriedades antimicrobiana, cicatrizante e antiinflamatória. O objetivo deste trabalho foi avaliar a influência da temperatura de entrada e a concentração de Aerosil®200 nas características de extratos secos por aspersão da Schinus terebinthifolius Raddi. Os extratos preparados com etanol 70 °GL foram secos em Mini-spray dryer, Buchi B191, com adição do adjuvante tecnológico numa proporção de 20:80; 25:75 e 30:70 (p/p) Aerosil®200: resíduo seco, variando a temperatura de entrada de 120 °C a 160 °C. A umidade residual, o rendimento final do produto e o aumento da massa frente à umidade relativa controlada de 90 % foram usados como critério de avaliação. A análise de superfície de resposta revelou que à medida que a temperatura e a concentração de Aerosil aumentam, diminui a umidade residual dos extratos, bem como sua higroscopicidade. As melhores condições de secagem foram a temperatura de entrada de 140 °C e 30 % do adjuvante, resultando em rendimento acima de 80 %.

Development of a Bacillus sphaericus tablet formulation and its evaluation as a larvicide in the biological control of Culex quinquefasciatus

This study aimed to analyze the final fermentation culture of Bacillus sphaericus 2362, standardize it and develop an active tablet formulation for use in urban mosquito breeding sites. It was performed in three phases: analysis and standardization of a B. sphaericus fermented culture; physical, chemical, and biological analysis of the active powder (solubility, residual humidity, particle size, resting angle, flowing off time, compacted density, and biological activity against Culex quinquefasciatus larvae); and the development of fast-disintegrating tablets. Five formulations with differing compositions were developed and a UV protector was added to the selected formulation. The formulation products with or without UV protector, as well as the active powder caused 100% larval mortality from 1 day to 2 months after a single treatment under simulated field conditions. These results show that the UV protector does not affect the initial larvicide activity of B. sphaericus, nor its persistence over a period of two months.

Optimization of the Design and Technology of Bactericidal Plasters. Technology and Properties of a New Bactericidal Plaster

Widely used self-adhesive bactericidal plasters produced by the Voronezh Chemico-Pharmaceutical Plant are now in growing demand. With a view to increase the volume of production, it was suggested to modify the technology of obtaining pads impregnated with antiseptics. The new method is based on impregnating a gauze with alcohol solution of antiseptics, followed by squeezing of the material and its drying in a flow of hot air. Since antiseptics used in bactericidal plasters are poorly soluble, it was necessary to develop the technology of impregnation. In order to find the optimum impregnation solution, we have studied the study solubilities of drugs involved in the two- and three-component mixtures in 40% aqueous ethanol at temperatures in the interval from 20 to 90°C. The test solutions were prepared by treating drug – ethanol mixtures in a shaker for 2 h, followed by keeping in a thermostat at a preset temperature for 4 h and filtering. Then, 2-ml samples were taken, dried at 100°C, and cooled in a desiccator. Finally, the amount of dissolved drugs was determined by gravimetry. The results of these experiments showed that solubilities of the drugs increase with the temperature. It is possible to divide the solubility curves into three regions. In the first region, extending from 20 to 35°C, the solubilities of all drugs and their mixtures slowly increase from 0.024 to 0.030 g per 100 ml of solvent. The second region corresponds to a moderate increase in the solubility from 0.030 to 0.122 g100 ml for furacilin and synthomycin in the interval from 35 to 75°C, while the solubility of Brilliant Green grows rapidly within 40 – 50°C. The third region is characterized by a rapid growth in the solubility of furacilin from 0.122 to 0.260 g100 ml (11 times the initial value) for the temperature increased only by 15°C (from 75 to 90°C). Based on these data, it is possible to accelerate the dissolution of furacilin by conducting the process at 75 – 90°C. The solubility of synthomycin in 40% aqueous ethanol is higher than that of furacilin: the curve of synthomycin exhibits a sharp jump at a lower temperature (65°C). Therefore, it is expedient to prepare synthomycin solutions at temperatures above 65°C. An analysis of the data for Brilliant Green showed that the solubility P = f (T ) of this drug behaves differently from those of furacilin and synthomycin and exhibits a rapid growth from 0.22 to 1.47 g100 ml (e.g., by 1.25 g100 ml) within 40 – 50°C. However, subsequent increase in the temperature above 60°C leads to a rather insignificant growth in the solubility: from 1.47 g100 ml at 60°C to 1.73 g100 ml at 80°C. Thus, the optimum temperature interval for dissolving Brilliant Green in 40% aqueous ethanol is within 30 – 60°C. Using the experimental data on solubility described above, we developed the following method of preparation of the impregnation solution. In the first stage, an ethanol solution of furacilin and synthomycin is prepared by stirring for 1 h at a temperature above 60°C. The stock solution of Brilliant Green is prepared separately at a temperature above 40°C. Then, a three-component solution is prepared by mixing the furacilin – synthomycin and Brilliant Green solutions at 55 – 60°C, stirring for not less than 30 min, and filtering through a hot filter. The solution is kept before use at the same temperature of 55 – 60°C. The experiments for optimization of the process of gauze pad impregnation were performed on an experimental setup of the LUNISL type by impregnating 10-m long 6-cm-wide two-fold gauze ribbons. The quality of impregnation was evaluated by homogeneity of the gauze staining. The samples exhibiting inhomogeneous coloration were rejected. The homogeneously stained samples were characterized with respect to the amount of adsorbed antiseptics, residual humidity after squeezing and drying in hot air flow, the amount of antiseptics retained after drying, and the final antiseptic activity determined by inhibition of the growth of Staphylococcus aureus.

Effect of different pre-treatments on drying of green table olives (<i>Ascolana tenera var</i>.)

Mature green olives ( Olea europea L .) were dried in a forced air oven at 50oC, after being subjected alternatively to four different pre-treatments. Results indicate the possibility to obtain bitter-free and high quality olives by combining a ten minutes dip in a 10 % hot brine (50oC) followed by a 32 hours dehydration. The latter product reached 20 % of residual humidity and did not rotted for one year.

Wall coating for DNA sequencing and fragment analysis by capillary electrophoresis

In capillary electrophoresis, covering the inner capillary surface with a coating is an efficient way to minimize both the electroosmotic flow and sorption of w analytes on the capillary wall. We modified the procedure by Cobb et al. Anal. . x Chem. 62, 2478 1990 for preparing wall coating to permit large-scale production. Specifically, we use a positive pressure to fill the capillary with both thionyl chloride and later vinylmagnesium bromide solution. This enables large-scale production of the coating by treating 100 m capillary pieces at a time. We found that no extensive flushing with either organic solvents or sodium hydroxide is needed before the reactions are performed. Application of liquid thionyl chloride with positive pressure scavenges residual humidity on the capillary surface and eliminates a need for extensive drying of the capillary. In the polymerization step, elimination of TEMED from the polymerization mixture and incubation at 708C enables a homogeneous coating to be prepared in capillaries as long as 100 m. The prepared wall coating is stable for approximately 110 runs of DNA sequencing in a denaturing matrix and over 300 runs of DNA fragment analysis under nondenatur- ing conditions. Q 1998 John Wiley & Sons, Inc. J Micro Sep 10: 175)184, 1998

Surface dynamics in tin dioxide-containing catalysts II. Competition between water and oxygen adsorption on polycrystalline tin dioxide

The interaction of polycrystalline tin dioxide with traces of water contained in argon or in oxygen during repeated temperature cycling between 20 and 400 °C has been followed by measuring in situ a.c. electrical conductivity and by thermogravimetry. In an ambient with residual humidity, water adsorption interferes with oxygen adsorption. The relative surface distribution of hydroxyl groups and oxygen species depends on the history of the sample.