Maximum Attainable Concentration Research Articles

The acute vapour inhalation toxicity of 2-butoxyethanol. Points considered when designing and conducting a study in Guinea pigs and evaluating existing inhalation toxicity data on low volatility solvents

This publication reports the outcome of an acute inhalation toxicity study with guinea pigs by nose-only exposure to the substance 2-butoxyethanol at exposures close to the maximum attainable saturation vapour concentration. We describe the methods used to ensure exposure only to saturation vapour at a level as high as could be practically achieved whilst avoiding aerosol formation. We consider the practical difficulties and implications of testing substances at or close to their saturation vapour concentration and the criteria that should be used to critically assess such studies, especially with reference to the GHS (Globally Harmonised System) for classification and labelling, where a clear differentiation between gases, vapours and dust and mists applies. Guinea pigs showed no adverse effects when exposed for 4 h to the maximum attainable concentration of pure 2-butoxyethanol vapour. If guinea pigs are regarded as the most appropriate species to assess short term toxicity to humans from exposure to 2-butoxyethanol, because they are like humans not sensitive to haemolysis of red blood cells caused by exposure to the substance, then the data from this study shows that 2-butoxyethanol presents a low acute inhalation toxicity hazard.

Comparison of achromatic doublet on glass Fresnel lenses for concentrator photovoltaics.

Silicone on glass (SoG) Fresnel lenses are the reference technology in concentrator photovoltaics (CPV) because of their simplicity and low cost. Nevertheless, their performance is strongly limited by chromatic aberration. As an alternative, in order to overcome such limitation, achromatic doublet on glass (ADG) Fresnel lenses were proposed. Such lenses are achromatic cemented doublet specifically designed for CPV applications. In this paper, a novel ADG architecture is presented and its performance analyzed and compared to previous proposals. The results show that most of the intrinsic optical losses are minimized and a superior optical efficiency can be achieved. The novel ADG design provides an achromatic lens for CPV whose efficiency is almost equal to the reference SoG technology and, at the same time, maintains all the advantages provided by the achromatic design such as the higher maximum attainable concentration and the strongly reduced temperature dependency.

Использование растворов борной кислоты в орга-нических жидкостях в качестве борсодержащих микро-удобрений. Влияние на урожайность и химический состав зерна озимой и яровой пшеницы

The conditions for dissolution of boric acid in monoethanolamine, diethanolamine, triethanolamine, glycerol, ethylene glycol and morpholine were selected, which made it possible to obtain low-viscosity solutions with a concentration that was many times higher than the max-imum attainable concentration in water and did not produce precipitates during storage. The resulting solutions were used as microfertilizers for foliar feeding and seed treatment of win-ter (Moskovskaya 56) and spring (Zlata) wheat. The use of boron as a microelement contributed to the preservation of a larger number of living plants of winter wheat during the wintering peri-od, and, consequently, the better winter hardiness of the crop. The maximum value of the winter wheat yield was obtained when the seeds were treated with monoethanolamine borate. The high-est values of the indicators of the yield structure belonged to the grain of winter wheat against the background of the seed treatment with a chelated form of boron: for the number and weight of grains when monoethanolamine borate was used; for the length of the ear when glycerol borate was used. The treatment of the Moskovskaya 56 wheat seeds with the microelement led to an increase in the amount of nitrogen in the grain relative to the control by 7–11 %. The highest values belonged to the variants including the treatment of seeds with the traditional form of the element (aqueous solution of boric acid), as well as the treatment with monoethanolamine borate. The maximum increase in the yield of the Zlata spring wheat was observed on feeding with a solution of boric acid in glycerol: 3.26 t / ha (2.1 times higher than on feeding with the traditional form of the microelement). Boron as a microelement contributed to an increase in the structural parameters of spring wheat plants in all forms. The greatest positive effect was noted from the action of glycerol borate, where the difference to the control variant was 2.4 times for the number of grains in an ear to the control, and their weight was 2.7 times. After the use of boron the spring wheat gluten was characterized as good (quality group I).

Features of Electrical Double Layers Formed Around Strongly Charged Nanoparticles Immersed in an Electrolyte Solution. The Effect of Ion Sizes

Using the modified Poisson–Boltzmann (PB) theory, which includes restrictions on the maximum attainable concentration of ionic species in a solution Cmax determined by their effective sizes, the distributions of electrostatic potential φ(r) and ion concentration near a spherical nanoparticle with radius a immersed in a 1 : 1 electrolyte solution have been studied under the conditions of constant surface charge density σs. For weakly charged particles, the φ(r) profiles are almost independent of Cmax and coincide with the profile obtained in terms of the classical PB model. Surface potential |φs| gradually increases with a rise in |σs|. Far from the particle, when the potential becomes lower than its thermal value $${{\varphi }_{{\text{T}}}} = \frac{{kT}}{e}$$ (k is the Boltzmann constant, T is the temperature, and e is the elementary charge), the potential decreases exponentially irrespective of the counterion sizes: $$\psi \left( r \right) = \frac{{\varphi \left( r \right)}}{{{{\varphi }_{{\text{T}}}}}} = {{\psi }_{{{\text{eff}}}}}\frac{a}{r}\exp \left( { - \kappa \left( {r - a} \right)} \right),$$ where r is the distance from the particle center and κ is the reciprocal Debye radius. According to the classical PB theory, the growth of the surface charge leads to the saturation of $$\left| {{{\psi }_{{{\text{eff}}}}}} \right|~\left( { \to 4} \right),$$ with the value of $$\left| {{{\psi }_{{\text{s}}}}} \right|$$ obtained by solving the nonlinear PB equation being higher than $$\left| {{{\psi }_{{{\text{eff}}}}}} \right|.$$ In the modified PB theory, which takes into account the size of electrolyte ions in the simplest form, this effect of saturation is absent. Now, $$\left| {{{\psi }_{{{\text{eff}}}}}} \right|$$ depends on both the value of the surface charge and the sizes of counterions. Moreover, at a large size of counterions, $$\left| {{{\psi }_{{{\text{eff}}}}}} \right|$$ substantially exceeds the corresponding value obtained by solving the nonlinear modified PB equation. The difference between the electrical double layer properties obtained by solving the classical and modified PB equations directly follows from the fact that the modified theory predicts the appearance of a condensed layer at a particle surface, with the concentration of counterions in this layer being equal to Cmax. Therewith, the thickness of the layer grows with increasing |σs| (at a constant size of the ions) and the size of the ions (at constant σs).

Study of electrodialysis concentration process of inorganic acids and salts for the two-stage conversion of salts into acids utilizing bipolar electrodialysis

The electrodialysis concentration process of sodium chloride, sodium sulfate, lithium chloride, ammonium nitrate, sulfuric and nitric acids were studied. Using the model of electrodialysis concentration, the transport coefficients of the Ralex CM-PP/Ralex AMH-PP membrane pair were calculated. It has been established that for salt solutions, the key factors determining the maximum attainable electrolyte concentration in the concentration chamber are the electromigration current efficiency and the hydration number of the electrolyte. For acid solutions, the most important factors determining their concentration are the osmotic and electroosmotic transport of water through the membrane. Besides, it was found that in the process of electrodialysis concentration of acids, proton leakage occurs through the strongly basic anion-exchange membrane from the concentration chamber to the desalination chamber, which significantly reduces the current efficiency. To obtain concentrated solutions of sulfuric acid with a low content of salt ions, a two-stage scheme for the recovery of the sodium sulfate into sulfuric acid using bipolar electrodialysis (BMED) and an electrodialyzer-concentrator (EDC) is proposed. A two-stage process, including BMED and EDC, for the conversion of sodium sulfate into sulfuric acid allows one to obtain acid with a concentration of up to 1.52 M by sulfate ion with a content of sodium ions of not more than 0.005 M. At a reasonable current density of 2 A/dm2 the obtained concentration of acid was 1.16 M by sulfate ion with current efficiency of 0.89 for BMED and 0.26 for EDC, total specific energy consumption of 0.83 kWh/mol SO42-, and acid flux of 0.024 mol SO42-·dm−2·h−1 (0.23 kg H2SO4·m−2·h−1). The obtained specific characteristics of the process are comparable with the characteristics of bipolar electrodialysis using industrial bipolar membranes.

LC-ESI-MS/MS method for the simultaneous determination of isoformononetin, daidzein, and equol in rat plasma: Application to a preclinical pharmacokinetic study

Isoformononetin (methoxy isoflavone) is a potent osteogenic isoflavone abundantly present in Butea monosperma, Pisum sativum, Mung bean, Machaerium villosum, Medicago sativa, and Glycine max. In the current study, an LC–ESI-MS/MS method for the simultaneous evaluation of isoformononetin (IFN), daidzein (DZN) and equol (EQL) was developed and validated in rat plasma using biochanin A as an internal standard. IFN, DZN, and EQL separation was achieved by using acetonitrile and acetic acid (0.1%) in the ratio of 90:10 (% v/v) as mobile phase under isocratic conditions at a flow rate of 0.6 mL/min on Atlantis C18 (4.6 × 250 mm, 5.0 μm) column. The achieved method was linear within the concentration range of 0.5–500 ng/mL. The method was effectively applied to investigate the permeability, protein binding estimation and pharmacokinetics studies of IFN in rats. The PAMPA permeability of IFN was found to be high at pH 4.0 and 7.0. The protein binding was found to be about 91% of IFN. The oral bioavailability of IFN was found to be poor (21.6%). IFN was found to have a moderate clearance (2.9 L/h/kg) and a large apparent volume of distribution (12.1 L/kg). The plasma half-life (t1/2) and maximum attainable concentration (Cmax) of IFN at systemic circulation was found to be 1.9 ± 0.6 h and 269.3 ± 0.4 after oral administration.

Deuterium concentration’s in austenitic stainless steel by deuterium irradiation. Effects temperature irradiation

Using the deuterium thermodesorption spectra from the 18Cr10NiTi steel samples exposed to different doses, we have plotted the total amount of deuterium desorbed from the sample as a function of the radiation dose and the irradiation temperatures. Temperature 100 K. The maximum attainable concentration of deuterium in steel is C=1 (at.D/at.met.= 1/1). At C≥0.5, two hydride phases are formed in the steel, the decay temperatures of which are 240 K and 275 K. The hydride phases are formed in the bcc structure resulting from the martensitic structural transformation in steel [1]. Temperature 295 K. The medium-dose region is characterized by radiation induced action on the steel in the presence of hydrogen. The process results in the formation of the energy-stable crystalline nanostructure of steel, having a developed network of intercrystalline boundaries. The basis for this developed network of intercrystalline boundaries is provided by the amorphous state. The total concentration of the accumulated deuterium in the region of medium implantation doses makes 7 to 8 at.% [2]. Temperature 380; 420; 600 and 900 K. In a deuterium thermodesorption spectra the extended area of deuterium desorption in a range of temperatures 450-900 K is observed, caused by formation of local structure in a radiation induced layer. Formation of local structure can be caused by a segregation of a steel component in the course of deuterium implantation (radiation induced local structure at deuterium presence).The total concentration of the accumulated deuterium in the region of medium implantation doses makes 1 to 3 at.%.

An Electrical Double Layer between Spherical Particles. The Effect of Ion Sizes

Using the modified Poisson–Boltzmann theory, which includes restrictions on the maximum attainable concentration of ionic species in the solution Cmax, determined by their effective dimensions, the spatial distributions of the electric potential and ions between spherical nanoparticles immersed in a 1 : 1 electrolyte solution have been investigated. It has been found that the pattern of the aforementioned distributions is governed by surface electric potential ψs of the particles, interparticle distance, and maximum concentration Cmax. Between weakly charged particles, the electric potential profiles are almost independent of the value of Cmax. As absolute value $$\left| {{{\psi }_{{\text{s}}}}} \right|$$ increases, an effect associated with the ionic sizes manifests itself; i.e., for high $$\left| {{{\psi }_{{\text{s}}}}} \right|$$ values, the electrical double layer expands into the solution, and, the lower Cmax (the larger the effective size of counterions), the higher the degree of expansion. This behavior is related to the fact that, near a particle surface, the profile of counterion concentration is developed with the following distinctly pronounced regions: the region of a plateau with width lc, which corresponds to the condensed part of the profile with C(x) = Cmax for 0 lc. When highly charged particles approach to each other up to such distances that their electrical double layers appear to be strongly overlapped, coions are completely displaced from the interparticle electrolyte layer, and only counterions are present in the layer.

Reliable determination of the induction period and critical reverse micelle concentration of lipid hydroperoxides exploiting a model composed of pseudo-first and -second order reaction kinetics

A combinational kinetic model was employed for the first time to determine the quantitative values of some kinetic parameters, including induction period (IP), critical reverse micelle concentration (CMC), and maximum attainable concentration of lipid hydroperoxides (PVmax) in a range of edible oils peroxidised at 60 °C. On the basis of the calculated coefficients of variation (CV), the model was able to estimate the kinetic parameters much better than the conventional tangent method. The potency of the combinational kinetic model to provide the values of markedly lower variability caused the small differences among the experimental results to be appeared statistically.

Indoor Experimental Assessment of the Efficiency and Irradiance Spot of the Achromatic Doublet on Glass (ADG) Fresnel Lens for Concentrating Photovoltaics.

We present a method to characterize achromatic Fresnel lenses for photovoltaic applications. The achromatic doublet on glass (ADG) Fresnel lens is composed of two materials, a plastic and an elastomer, whose dispersion characteristics (refractive index variation with wavelength) are different. We first designed the lens geometry and then used ray-tracing simulation, based on the Monte Carlo method, to analyze its performance from the point of view of both optical efficiency and the maximum attainable concentration. Afterwards, ADG Fresnel lens prototypes were manufactured using a simple and reliable method. It consists of a prior injection of plastic parts and a consecutive lamination, together with the elastomer and a glass substrate to fabricate the parquet of ADG Fresnel lenses. The accuracy of the manufactured lens profile is examined using an optical microscope while its optical performance is evaluated using a solar simulator for concentrator photovoltaic systems. The simulator is composed of a xenon flash lamp whose emitted light is reflected by a parabolic mirror. The collimated light has a spectral distribution and an angular aperture similar to the real Sun. We were able to assess the optical performance of the ADG Fresnel lenses by taking photographs of the irradiance spot cast by the lens using a charge-coupled device (CCD) camera and measuring the photocurrent generated by several types of multi junction (MJ) solar cells, which have been previously characterized at a solar simulator for concentrator solar cells. These measurements have demonstrated the achromatic behavior of ADG Fresnel lenses and, as a consequence, the suitability of the modelling and manufacturing methods.

Indoor Experimental Assessment of the Efficiency and Irradiance Spot of the Achromatic Doublet on Glass (ADG) Fresnel Lens for Concentrating Photovoltaics

We present a method to characterize achromatic Fresnel lenses for photovoltaic applications. The achromatic doublet on glass (ADG) Fresnel lens is composed of two materials, a plastic and an elastomer, whose dispersion characteristics (refractive index variation with wavelength) are different. We first designed the lens geometry and then used ray-tracing simulation, based on the Monte Carlo method, to analyze its performance from the point of view of both optical efficiency and the maximum attainable concentration. Afterwards, ADG Fresnel lens prototypes were manufactured using a simple and reliable method. It consists of a prior injection of plastic parts and a consecutive lamination, together with the elastomer and a glass substrate to fabricate the parquet of ADG Fresnel lenses. The accuracy of the manufactured lens profile is examined using an optical microscope while its optical performance is evaluated using a solar simulator for concentrator photovoltaic systems. The simulator is composed of a xenon flash lamp whose emitted light is reflected by a parabolic mirror. The collimated light has a spectral distribution and an angular aperture similar to the real Sun. We were able to assess the optical performance of the ADG Fresnel lenses by taking photographs of the irradiance spot cast by the lens using a charge-coupled device (CCD) camera and measuring the photocurrent generated by several types of multi junction (MJ) solar cells, which have been previously characterized at a solar simulator for concentrator solar cells. These measurements have demonstrated the achromatic behavior of ADG Fresnel lenses and, as a consequence, the suitability of the modelling and manufacturing methods.

Whey recovery using forward osmosis – Evaluating the factors limiting the flux performance

The focus of whey processing has been changed from waste treatment to the production of valuable products owing to the advancement of membrane technology. Producing high quality whey products at low energy consumption entails novel techniques for whey concentration. This study proposes forward osmosis (FO) as a potential approach to concentrate whey protein solutions, which is superior to the concentration via reverse osmosis (RO), mainly owing to the low hydraulic pressure during FO process. In particular, this work validated the feasibility of FO-based whey concentration using high-performance hollow fiber membranes that were fabricated in-house. The investigation focused on the effects of various operating conditions on the concentration performance. The experimental results reveal that optimal concentration efficiency would be achieved by appropriately choosing the cross-flow velocity, draw solution concentration and the maximum attainable concentration of whey protein solution. Especially, the flux decline behaviour as a function of the whey protein concentration in the feed solution indicated rapid formation of a polarized or gel foulant layer at the membrane surface. The proposed mechanism was supported by the investigation of physical cleaning with water, showing that the post-process cleaning after the concentration cycle was able to recover the membrane performance, whereas the intermediate cleaning during one concentration cycle had little impact on the concentration efficiency enhancement. This study has practical significance for the application of FO in the concentration of dairy streams and other liquid foods.

In-line sample concentration by evaporation through porous hollow fibers and micromachined membranes embedded in microfluidic devices.

Two types of microfluidic systems, a porous hollow fiber and a thin supported membrane with an array of micromachined holes, are investigated for concentrating mass-limited analyte samples. Water evaporation is driven by the partial pressure difference across the hydrophobic membrane, induced by dry sweeping gas on the permeate side. An analytical model permitting clarification of the contribution of design and process parameters on acquisition of concentrated solution and prediction of achievable concentration factors is presented. Concentrating an exemplary solution utilizing the two systems has been studied at different experimental conditions to validate the model. The results show that the hollow fiber gives controllable concentration factors of more than 10. For the micromachined membrane concentrator concentration factors of 6-8 were achieved, at much lower flow rates than predicted by the model. Because of the asymptotic dependence of concentration factor on flow rate, accurate control of the liquid feed is extremely critical in the flow rate range where high concentration factors are obtained, and the smallest variations in liquid flow rate may easily lead to supersaturation and deposition of solutes in the pores. This changes membrane porosity in an unpredictable way and limits the maximum attainable concentration factor.

Structural transformations in austenitic stainless steel induced by deuterium implantation: irradiation at 100K.

Deuterium thermal desorption spectra were investigated on the samples of austenitic stainless steel 18Cr10NiTi preimplanted at 100 K with deuterium ions in the dose range from 3 × 1015 to 5 × 1018 D/cm2. The kinetics of structural transformation development in the implantation steel layer was traced from deuterium thermodesorption spectra as a function of implanted deuterium concentration. At saturation of austenitic stainless steel 18Cr10NiTi with deuterium by means of ion implantation, structural-phase changes take place, depending on the dose of implanted deuterium. The maximum attainable concentration of deuterium in steel is C = 1 (at.D/at.met. = 1/1). The increase in the implanted dose of deuterium is accompanied by the increase in the retained deuterium content, and as soon as the deuterium concentration attains C ≈ 0.5 the process of shear martensitic structural transformation in steel takes place. It includes the formation of bands, body-centered cubic (bcc) crystal structure, and the ferromagnetic phase. Upon reaching the deuterium concentration C > 0.5, the presence of these molecules causes shear martensitic structural transformations in the steel, which include the formation of characteristic bands, bcc crystal structure, and the ferromagnetic phase. At C ≥ 0.5, two hydride phases are formed in the steel, the decay temperatures of which are 240 and 275 K. The hydride phases are formed in the bcc structure resulting from the martensitic structural transformation in steel.

Amphiphilic Block Copolymer Vesicles for Active Wound Dressings: Synthesis of Model Systems and Studies of Encapsulation and Release

SummaryPolystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA) diblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Self‐assembly of these block copolymers into polymeric vesicles, so‐called polymersomes, was performed by addition of water to a solution of the block copolymers in tetrahydrofuran (THF). Various antimicrobial compounds and dyes were incorporated in the polymersomes and in addition to the corresponding size distributions, as determined by dynamic light scattering (DLS), the maximum attainable loading concentrations were determined. Using the release of incorporated calcein, which is a pH responsive dye, the principle of a light up probe approach for advanced in situ diagnostics was demonstrated. The release from PS‐b‐PAA vesicles via a vesicle‐to‐micelle transition was triggered by heating a vesicle suspension after addition of the plasticizer THF to 50 °C. Furthermore, a biocompatible and degradable block copolymer system, which contains degradable ester bonds in the main chain, was synthesized and investigated. In particular, poly(ethylene glycol)‐block‐polycaprolactone (PEG‐b‐PCL) copolymers were synthesized via ring‐opening polymerization (ROP). These copolymers were shown to form polymersomes as well and represent a promising family of degradable amphiphilic block copolymers for active wound dressings and related applications.

Toward the Establishment of Standardized in Vitro Tests for Lipid-Based Formulations. 2. The Effect of Bile Salt Concentration and Drug Loading on the Performance of Type I, II, IIIA, IIIB, and IV Formulations during in Vitro Digestion

The LFCS Consortium was established to develop standardized in vitro tests for lipid-based formulations (LBFs) and to examine the utility of these tests to probe the fundamental mechanisms that underlie LBF performance. In this publication, the impact of bile salt (sodium taurodeoxycholate, NaTDC) concentration and drug loading on the ability of a range of representative LBFs to generate and sustain drug solubilization and supersaturation during in vitro digestion testing has been explored and a common driver of the potential for drug precipitation identified. Danazol was used as a model poorly water-soluble drug throughout. In general, increasing NaTDC concentrations increased the digestion of the most lipophilic LBFs and promoted lipid (and drug) trafficking from poorly dispersed oil phases to the aqueous colloidal phase (AP(DIGEST)). High NaTDC concentrations showed some capacity to reduce drug precipitation, although, at NaTDC concentrations ≥3 mM, NaTDC effects on either digestion or drug solubilization were modest. In contrast, increasing drug load had a marked impact on drug solubilization. For LBFs containing long-chain lipids, drug precipitation was limited even at drug loads approaching saturation in the formulation and concentrations of solubilized drug in AP(DIGEST) increased with increased drug load. For LBFs containing medium-chain lipids, however, significant precipitation was evident, especially at higher drug loads. Across all formulations a remarkably consistent trend emerged such that the likelihood of precipitation was almost entirely dependent on the maximum supersaturation ratio (SR(M)) attained on initiation of digestion. SR(M) defines the supersaturation "pressure" in the system and is calculated from the maximum attainable concentration in the AP(DIGEST) (assuming zero precipitation), divided by the solubility of the drug in the colloidal phases formed post digestion. For LBFs where phase separation of oil phases did not occur, a threshold value for SR(M) was evident, regardless of formulation composition and drug solubilization reduced markedly above SR(M) > 2.5. The threshold SR(M) may prove to be an effective tool in discriminating between LBFs based on performance.

몬테카를로 광선추적법을 이용한 태양로의 열유속 해석

태양의 집광 열유속을 이해하는 것은 태양에너지를 이용하는 시스템의 해석과 설계에 중요하다. 본 연구는 우수한 유연성과 확장성을 가진 몬테카를로 광선추적법에 기반하면서 태양주연감광과 반사판 표면 기울기 에러를 고려하는 알고리듬 개발과 이를 통한 태양 열유속 해석에 초점을 맞추고 있다. 검증을 위해 한국에너지기술연구원 태양로에서 측정된 열유속과 비교했을 때, 모델링 결과가 측정 에러 범위인 10% 이내에서 잘 일치하였다. 개발된 모델을 통해 태양로의 집광 성능을 2 mrad 의 추적 정밀도에 최대로 도달 가능한 집광비가 4400 sun 으로 평가하였다. 열유속의 측정 위치에 따른 변화와 수광각에 따른 분포를 통해 화학반응기나 보조집광기 설계에 필요한 상세한 정보를 제공하였다.

Preparation of highly concentrated nanostructured dispersions of controlled size

This article presents the use of a shearing procedure for the preparation of stable nanostructured dispersions of lipid mesophases. This new application of the shearing technique is compared with the well-established ultrasonication method for the emulsification of these mesophases in water in terms of particle size, particle size distribution and available concentration range. With a laboratory-built shear device based on a Couette cell, it was possible to produce high quantities of internally self-assembled emulsion particles of controlled size at concentrated hydrophobic phase contents ( ϕ o ) of up to 70 wt%. The concentration limit of 70 wt% could be reached however, the maximum attainable concentration depended on the internal structure type of the particles. The limit was thus easily attained for emulsified microemulsions (EME) as well as for the emulsified inverse hexagonal phase ( H 2 ), whereas it was found to be lower for emulsified discontinuous ( Fd3m) and bicontinuous ( Pn3m) cubic phases. Moreover, by shearing, it was possible to keep the size of the particles relatively constant when increasing ϕ o , whereas the particle size significantly increased with ϕ o when ultrasonication was employed. By means of ultrasonication, the hydrodynamic radius of the particles could be tuned linearly between 85 to 180 nm as a function of ϕ o up to a maximum of 20 to 30 wt%. Below the maximum concentration limit, particles displayed a well-controlled size.

Effect of light intensity and frequency of flashing light from blue light emitting diodes on astaxanthin production by Haematococcus pluvialis

Flashing light from blue light emitting diodes is an effective method for the reduction of energy consumption in the bioproduction of astaxanthin by Haematococcus pluvialis. We investigated the effects of light intensity and frequency on the final astaxanthin concentration in bioproduction by H. pluvialis grown mixotrophically. The final astaxanthin concentration under illumination with flashing light, with frequencies ranging from 25 to 200 Hz, was dependent on the light intensity and on the duty cycle and was equivalent, or higher, in comparison with that under illumination with continuous light at the same incident intensity. The light intensity determined the maximum attainable concentration of astaxanthin under continuous illumination. Under illumination with flashing light, the ratio of the final astaxanthin concentration to the maximum concentration at a specific light intensity was correlated to the duty cycle in the frequency range from 25 to 200 Hz. The effect of lower frequencies on enhanced astaxanthin production under flashing light was also studied; at levels as low as 1 Hz, higher final astaxanthin concentrations were observed under flashing light compared to concentrations attained under continuous light.

Solutions in the calcium oxide-ethylene glycol-water system

A comprehensive study of solutions formed in dissolution of calcium oxide in ethylene glycol and in its mixtures with water was carried out. The major form of compounds in the solutions was established. The maximum attainable concentration of Ca(II) in solutions was determined in relation to the temperature and composition of the mixed solvent.