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The objective of this paper is to solve the Hilbert singular integral equation of first and second kind by using the Hilbert formula and some known results are obtained as special cases. Applications of these singular integral equations to Boundary value problems of Elasticity and allied subjects are well known.

Excitation functions of the reactions nat Ti( α , x ) 48 Cr, nat Ti( α , x ) 48 V and nat Ti( α , x ) 46,48 Sc were determined by the stacked-foil activation technique up to 40 MeV. The radioactivities produced in the nat Ti target were measured by γ-ray spectrometry using HPGe detector. The reaction nat Ti( α , x ) 51 Cr was used to determine the beam parameters. New experimental values for the above reactions have been obtained. An intercomparison of our data with the available literature values has been done. The cross section results obtained in this work could be useful in defining new monitor reactions, radiation safety and isotope production.

Good quality oil with high unsaturated fatty acids was found in the seed of a medicinal plant Phaleria macrocarpa (Mahkota dewa). Different parts especially fruit flesh of this plant are being traditionally used as important folk medicine whereas seed of this plant is usually neglected. In this study, the oil was extracted from P. macrocarpa seed using supercritical carbon dioxide. The extraction parameters were optimized by central composite design (CCD) of response surface methodology (RSM). Due to the non-linearity of the extraction process, artificial neural network (ANN) was also applied for predicting the oil yield. The optimum conditions obtained from RSM were 72 °C, 42 MPa and 4.5 ml/min CO2 flow rate where the oil yield was 52.9 g per 100 g of dry sample and coefficient of determination (R2) was 0.99. The ANN and RSM prediction showed similar R2 of 0.99 and ANN has lower average absolute deviation (AAD) of 0.25% compared to RSM (AAD of 0.31%). Five fatty acids were identified by gas chromatography–mass spectroscopy (GC–MS) analysis of the oil. The amount of oleic acid (18:1) was found to be highest (43.56%) among all the fatty acids. The total unsaturated fatty acid was 73.62% and saturated fatty acid was 26.38% in the P. macrocarpa seed oil.

The cross section of the 71 Ga(n,γ) 72 Ga reaction at 0.0334 eV was measured for the first time using monochromatic neutrons from powder diffractometer at TRIGA Mark II nuclear reactor. The 197 Au(n,γ) 198 Au reaction was used to monitor the neutron beam intensity. The HPGe γ-ray spectrometry was used to determine the radioactivity of the product radionuclides. The obtained cross section value amounted 3.42 ± 0.27 b is about 95% consistent with JENDL-4, but about 17% and 14% lower than that of the ENDF/B-VII and TENDL-2012 data libraries, respectively. The measured value at 0.0334 eV and the previous measured value at 0.0536 eV would be useful to confirm the reliability of the data evaluated by 1/ v relation in the above libraries.

The concentrations of minor and trace elements, including some of environmental significance, were determined in coals and ashes of Barapukuria thermal power plant in Bangladesh by a neutron activation analysis technique. Synchronized sampling of feed coal, fly ash, and bottom ash was undertaken over a limited time period. The ranges and arithmetic mean of the concentrations of 30 minor and trace elements in the coals and ashes are presented for the first time. Study of the enrichment factor relative to crustal abundances (Clarke values) indicates that Barapukuria coals are moderately enriched (2–6 times) with Sm, Dy, La, Ce, Th, Nd, W, Hf, Sb, and U. Distribution of the trace elements into fly ash and bottom ash after combustion in the power plant was also studied.

Surface-functionalized magnetic nanoparticles are widely used in various fields of biotechnology. In this study, beta-cyclodextrin-conjugated magnetic nanoparticles (CD-APES-MNPs) are synthesized and the use of CD-APES-MNPs as a solid-phase artificial chaperone to assist protein refolding in vitro is demonstrated using carbonic anhydrase bovine (CA) as model protein. CD-APES-MNPs are fabricated by grafting mono-tosyl-beta-cyclodextrin (Ts-beta-CD) onto 3-aminopropyltriethoxysilane (APES)-modified magnetic nanoparticles (APES-MNPs). Results obtained from transmission electron microscopy (TEM) and vibrating sample magnetometery (VSM) show that the synthesized magnetic nanoparticles are superparamagnetic with a mean diameter of 11.5 nm. The beta-CD grafting is confirmed by Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The amount of beta-CD grafted on the APES-MNPs is found to be 0.042 mmol g(-1) from elemental analysis. Our refolding results show that a maximum of 85% CA refolding yield can be achieved using these beta-CD-conjugated magnetic nanoparticles which is at the same level as that using liquid-phase artificial chaperone-assisted refolding. In addition, the secondary and tertiary structures of the refolded CA are the same as those of native protein under optimal conditions. These results indicate that CD-APES-MNPs are suitable and efficient stripping agents for solid-phase artificial chaperone-assisted refolding due to easier and faster separation of these nanoparticles from the refolded samples and also due to recycling of the stripping agents.

The thermal neutron-induced activation cross section for the 186 W( n , γ ) 187 W reaction was measured at 0.0536 eV neutron energy using TRIGA Mark-II research reactor, Atomic Energy Research Establishment, Savar, Dhaka, Bangladesh. The 197 Au( n , γ ) 198 Au monitor reaction induced in a high-purity gold foil was used to determine the effective neutron beam intensity. The activities induced in sample and monitor foils were measured nondestructively by a high-resolution HPGe γ -ray detector. The present experimental cross-section value is the first one at 0.0536 eV. The obtained new cross section that amounts to 26.6±1.6 b is 2% higher than the recently reported data in ENDF/B-VII and 5% lower than that of JENDL-3.3.

The neutron capture cross-section for the 71 Ga(n, γ) 72 Ga reaction at 0.0536 eV energy was measured using activation technique based on TRIGA Mark-II research reactor. The 197 Au(n, γ) 198 Au monitor reaction was used to determine the effective neutron flux. Neutron absorption and γ-ray attenuation in gallium oxide pellet were corrected in determination of cross-section. The cross-section for the above reaction at 0.0536 eV amounts to 2.75 ± 0.14 b. As far as we know there are no experimental data available at our investigated energy. So far we are the first, who carried out experiment with 0.0536 eV neutrons for cross-section measurement. The present result is larger than that of JENDL-3.3, but consistent within the uncertainty range. The value of ENDF/B-VII is higher than this work. The result of this work will be useful to observe energy dependence of neutron capture cross-sections.

Adsorption of globular protein, lysozyme, on thermosensitive poly(N-isopropylacrylamide) coated nanomagnetic particles was studied at different temperatures and pHs. It was observed that a maximum amount of lysozyme was adsorbed at a temperature above the lower critical solution temperature (LCST) (32 degrees C ) of the polymer and at the isoelectric point (pI=11) of lysozyme. Desorption was carried out using either NaH2PO4 (pH 4) or NaSCN (pH 6) as the desorbing agents. Conformational changes in lysozyme on desorption from nanomagnetic particles was studied by circular dichroism and intrinsic fluorescence spectroscopy. Lysozyme desorbed by NaH2PO4 showed very little conformational changes while lysozyme desorbed by NaSCN showed significant conformational changes, and 87% enzymatic activity was retained in the desorbed enzyme for desorption by NaH2PO4.

The effects of periphyton grown on bamboo substrate, on growth and production of Nile tilapia, Oreochromis niloticus (Genetically Improved Farmed Tilapia strain) in monoculture and polyculture with the freshwater prawn (Macrobrachium rosenbergii) were studied and economically evaluated. The experiment had 2 × 2 factorial design: The first factor was presence or absence of substrate for periphyton development, the second factor was related to culture system. The first system was monoculture of the GIFT strain of Nile tilapia stocked at 20,000 fingerlings ha¿ 1, the second system was tilapia¿prawn polyculture with each stocked at 20,000 fingerlings or postlarvae ha¿ 1. Bamboo poles were posted vertically in ponds under substrate treatments. Feed and inorganic fertilizers were applied to all ponds. There were no differences in phytoplankton biomass and primary productivity between the treatments (P > 0.05). The electivity indices indicated that there were low dietary overlaps between tilapia and prawn. Survivals of tilapia and prawn were higher in ponds with bamboo substrate (60% and 35%, respectively) than in the control ponds without substrates (55% and 20%, respectively). Addition of substrate significantly (P

Reactive extraction of gold from alkaline aqueous cyanide solution into n-decanol in the presence of Kryptofix 22 DD as complexing agent was studied using a stirred transfer cell. The study investigated the effects of carrier concentration and temperature on mass transfer rates. A two-film model was proposed by considering film mass transfer resistances at the aqueous and organic phases. The model predicted adequately the experimental time-concentration data at different carrier concentrations and temperatures. Experiments have also been carried out to extract gold in an emulsion system using the same carrier and a mixed solvent of kerosene and decanol.

Stripping of L-phenylalanine from organic phase containing ALIQUAT 336 (tri-octyl-methyl-ammonium chloride) as complexing agent was studied using a stirred transfer cell. The study investigated the effects of concentration of the stripping agent, potassium chloride, in strip solution and temperature on mass transfer rates. A two-film model based on organic and aqueous phases mass transfer resistances was proposed to estimate mass transfer coefficients and it predicted adequately the experimental time-concentration data at different conditions studied. A comparison of mass transfer coefficients for stripping and previously published results on extraction for the same system was made.

Thermosensitive polymer coated nanomagnetic adsorbents were synthesized by seed polymerization using surface modified nanomagnetic particles as the seeds. The Fe3O4 nanomagnetic particles were prepared by chemical precipitation of Fe2+ and Fe3+ salts in the ratio of 1:2 under alkaline and inert condition. The surface of these particles was modified by surfactants to achieve stability against agglomeration. These stable particles were then polymerized using N-isopropylacrylamide (NIPAM) as the main monomer, methylene-bis-acrylamide as the crosslinker and potassium per sulfate as the initiator. The thermosensitive adsorbents were characterized by using transmission electron micrography (TEM) and vibrating sample magnetometer (VSM). TEM showed that the particle remained discrete with a mean diameter of 12 nm. Magnetic measurements revealed that the particles are superparamagnetic only with a decrease of magnetism after binding with the polymer due to the increase in surface spin disorientation. Pure Fe3O4 spinel structure of these nanoparticles was indicated by the X-ray diffraction (XRD) patterns. The polymerization of NIPAM with the surface modified nanomagnetic particles was confirmed by Fourier transform spectroscopy (FTIR), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). In addition, the adsorption/desorption of BSA molecule on these thermosensitive nanoparticles was investigated as a function of temperature. More than 60% desorption efficiency was achieved under appropriate condition.

Core–shell type thermosensitive magnetic particles were prepared via seed polymerization process. Double layer surfactant coated magnetic particles were first synthesized and then a rich poly-(N-isopropylacrylamide) (PNIPAM) shell layer was attached using double layer magnetic particles as the seeds. Thiodiglycolic acid was used as the primary surfactant and 4-vinylaniline as the secondary surfactant. Carboxylated thermosensitive microspheres were prepared by adding methacrylic acid (MAA) in the polymerization process. PNIPAM has a lower critical solution temperature (LCST) of 32 °C in water, and changes from hydrophilic below the LCST to hydrophobic above it. The size of these thermosensitive polymer coated magnetic particles was measured by using transmission electron microscopy (TEM). TEM results show that magnetic particles were nanosized and the calculated mean diameter of the particles was about 12 nm. Bovine serum albumin (BSA) was selected as a model protein for the separation study. Adsorption of BSA on the thermosensitive magnetic particles was mainly dependent on the properties of the particles’ surface. By increasing the temperature above the LCST of PNIPAM, the particles shrank and were able to adsorb larger quantity of proteins, which was subsequently desorbed at lower temperature. It was believed that carboxylated thermosensitive particles adsorb proteins through hydrogen bonding. When the two extremes of hydrophobic interaction and hydrogen bonding were compared, it was found that more proteins are adsorbed using the later interaction.

Adsorption and desorption behavior of Bovine Serum Albumin (BSA) on surface-modified magnetic nanoparticles covered with thermosensitive polymer (PNIPAM) was investigated as a function of temperature, pH, and ionic strength. Functionalization of surface-modified magnetic particles was performed by seed polymerization using N-isopropylacrylamide (PNIPAM) as the main monomer. Characterization of these particles was carried out using transmission electron micrography (TEM), and vibrating sample magnetometry (VSM). The adsorption results exhibited both pH and temperature sensitivity. The results showed that the temperature effect on adsorption/desorption behavior was mainly dependent on the properties of the particles' surface. The effect of pH was also investigated and it was observed that a smaller amount of protein was adsorbed at higher pH because of the electrostatic repulsive force between protein molecules and latex particles. The maximum amount of protein was adsorbed near the isoelectric point of BSA. Desorption results showed that more protein was desorbed when adsorption was done at lower temperatures and desorption efficiency was found to be higher than 80%.

The unique and novel physicochemical features of the nanosized magnetic particles, which are attained due to their size and shape morphology, have aggregated an interest in the fields of nanoscience and nanotechnology. In this work, magnetic particles coated with double-layer surfactants were prepared and characterized. The magnetic particles ( Fe3O4 ) were synthesized by chemical precipitation of Fe2+ and Fe 3+ salts (1:2 ratio) with ammonium hydroxide ( NH4OH ) under inert atmosphere at 80°C followed by resuspension of the nanoparticles in water using thiodiglycolic acid. This procedure produced Fe3O4 nanoparticles stabilized against agglomeration. The primary surfactant coated particles were further treated with 4-vinylaniline at 25°C for about thirty minutes. As –SH group in thiodiglycolic acid has greater affinity formagnetic surface, it is easily attached to the iron particles through bonding. Subsequently, the – NH2 functional group of 4-vinylaniline reacts with the acid group – COOH of the thiodiglycolic acid. The size and the distribution of these magnetic particles, their morphologies and magnetic properties were measured by Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM), respectively. TEM results show the formation of single domain nanoparticles of mean diameter of about 10 nm. The strength of the NH–CO bond was measured by FTIR (Bio-Rad), the vibration observed at a wavelength of 1613–1745 cm-1. Thermo gravimetric analysis (TGA) reveals the existence of two distinct layers of surfactants on the particle surface. These surface-modified nanomagnetic particles can further be coated with thermo-sensitive polymeric materials which may be used in separation and purification of bio-molecules.

Adsorptions of bovine serum albumin (BSA) on nano-sized magnetic particles with and without the presence of carbodiimide were studied. Desorption of BSA from magnetic particles were carried out in either NaOH or Na 2 HPO 4 solutions. The structures of native BSA, adsorbed BSA on magnetic particles, and desorbed BSA were studied by several methods, circular dichroism (CD), fluorescence spectroscopy and differential scanning calorimetry (DSC). The magnitude of conformational changes of protein was determined by calculating the α-helix content from the circular dichroism (CD) spectra and by evaluating fluorescence spectrum and DSC thermograms. Adsorbed BSA on magnetic particles shows no thermal transition with respect to the native BSA. The structural change of BSA when desorbed by Na 2 HPO 4 solution is much smaller in comparison to that when desorbed by NaOH solution. Hence, this indicates that BSA could be desorbed from nano-sized magnetic particles using Na 2 HPO 4 without much conformational change.

The application of phase-change materials (PCM) for solar thermal-energy storage capacities has received considerable attention in recent years due to their large storage capacity and isothermal nature of the storage process. This study deals with the preparation and characterization of encapsulated paraffin-wax. Encapsulated paraffin particles were prepared by complex coacervation as well as spray-drying methods. The influence of different parameters on the characteristics and performance of a microencapsulated PCM in terms of encapsulation efficiency, and energy storage and release capacity has been investigated. The distribution of particle size and the morphology of microencapsulated PCM were analyzed by a scanning electron microscope (SEM). In the coacervation method, the optimum homogenizing time is 10 min and the amount of cross-linking agent is 6–8 ml. Results obtained from a differential scanning calorimeter (DSC) show that microcapsules prepared either by coacervation or the spray-drying method have a thermal energy storage/release capacity of about 145–240 J/g. Hence, encapsulated paraffin wax shows a good potential as a solar-energy storage material.

Microencapsulated paraffin, a novel solar storage material, was prepared by simple coacervation technique and its performance characteristics, when subjected to cyclic operation, were evaluated in terms of structure and particle profile using SEM and FTIR, and the energy storage and release capacity expressed by DSC. The microencapsulated paraffin has shown large energy storage and release capacity (56∼58 J/g) during its phase change, and maintains its energy storage and release capacity, chemical characteristics and structural profile even after one thousand thermal recycles.

Retention of ascorbic acid (vitamin C) in dried guava during storage was studied. The effects of storage temperature: 30°C, 40°C, 50°C and water activity (aw): 0.43, 0.75, 0.84, 0.97 were investigated. The degradation of ascorbic acid follows a pseudo-first-order reaction. The rate constant increased about four to six fold when storage condition was changed from aw=0.43–0.97. The rate constants and corresponding water activities are related by a second-order polynomial equation. The effect of temperature on the rate constant followed the Arrhenius relationship. The activation energy of ascorbic acid degradation is found to be in the range 3.4–11.0 kcal/mol. An empirical equation, based on temperature, water activity and rate constant, is developed to predict shelf life of dried guava in respect of ascorbic acid retention.

Microencapsulated paraffin, a novel solar storage material, was prepared by complex coacervation technique and its performance was evaluated in terms 1of encapsulation ratio, hydrophilicity, energy storage capacity, and size distribution. The experiments were designed, based on surface response method, to optimise the processing conditions. The sizes of the microencapsulated paraffin particle were 50–100 μm. For an emulsification time of l0min and the addition of 6–8 ml (2.9−3.8% w/w) of formaldehyde (HCHO), the paraffin encapsulation ratio was found higher in different ratio of paraffin wax to coating (menu). It was also found that a higher coating to paraffin ratio leads to a higher paraffin encapsulation ratio. The hydrophilicity value of microencapsulated paraffin depended mainly on the ratio of paraffin to coating. The higher the ratio, the lower was its product hydrophilicity. In the same ratio of paraffin wax to coating, the higher concentration of HCHO led to a lower hydrophilicity of the product....

Emulsion Liquid Membrane (ELM) is a separation technique, which requires organic solvent, extractant and surfactant for its formulation. All the components play important roles. Surfactant adds stability to the emulsion but at higher concentration lowers extraction rate. Some surfactants, known as bi-functional surfactants, have dual properties of an extractant and an emulsifier. Use of such surfactant may eliminate the addition of an extractant to ELM system. In this study, polyethylene glycol was used as bi-functional surfactant in an ELM process for the extraction of metal ions from a ternary (copper, nickel and cobalt) aqueous solution. Dichloroethane, ammonium thiocyanate and potassium hydroxide were used as solvent, ligand and stripping agent, respectively. The paper presents the results on the characterization of the reactions (stoichiometry and reaction order) obtained through equilibrium and kinetic studies along with some batch emulsion extraction results.

Chiral resolution aromatic amino acids, dl-tryptophan (dl-Trp), dl-phenylalanine (dl-Phe), dl-tyrosine (dl-Tyr) from phosphate buffer solution was achieved in present study employing the concept of selective adsorption by surface functionalized magnetic nanoparticles (MNPs). Surfaces of magnetic nanoparticles were functionalized with silica and carboxymethyl-β-cyclodextrin (CMCD) to investigate their adsorption resolution characteristics. Resolution of enantiomers from racemic mixture was quantified in terms of enantiomeric excess using chromatographic method. The MNPs selectively adsorbed l-enantiomers of dl-Trp, dl-Phe, and dl-Tyr from racemic mixture and enantiomeric excesses (e.e.) were determined as 94%, 73% and 58%, respectively. FTIR studies demonstrated that hydrophobic portion of enantiomer penetrated into hydrophobic cavity of cyclodextrin molecules to form inclusion complex. Furthermore, adsorption site was explored using XPS and it was revealed that amino group at chiral center of the amino acid molecule formed hydrogen bond with secondary hydroxyl group of CMCD molecule and favorability of hydrogen bond formation resulted in selective adsorption of l-enantiomer. Finally, stability constant (K) and Gibbs free energy change (−ΔG°) for inclusion complexation of CMCD with l-/d-enantiomers of amino acids were determined using spectroflurometry in aqueous buffer solution. Higher binding constants were obtained for inclusion complexation of CMCD with l-enantiomers compared to d-enantiomers which stimulated enantioselective properties of CMCD functionalized magnetite silica nanoparticles.

Carbon paste electrodes containing powdered cation exchange resin (Amberlite IR120) have been fabricated and applied to the uptake of copper ion in aqueous solution. The copper uptake reaction was carried out at open circuit and at different cathodic potentials. Linear potential sweep voltammetry was used to quantify the accumulated ions. With the application of an optimum cathodic potential, the amount of copper absorbed increased four to nine-fold in comparison with similar uptake at open circuit conditions. The effect of different resin size employed in the chemically modified electrodes, on the sensitivity of the electrode response was also studied as a function of peak current.

A novel magnetic nanoadsorbent (CMCD-APTS-MNPs) containing the superparamagnetic and molecular recognition properties was synthesized by grafting carboxymethyl-β-cyclodextrin (CM-β-CD) on 3-aminopropyltriethoxysile (APTS) modified Fe(3)O(4) nanoparticles. The feasibility of using CMCD-APTS-MNPs as magnetic nanoadsorbent for selective adsorption of adenosine (A) and guanosine (G) based on inclusion and molecular recognition was demonstrated. The as-synthesized magnetic nanoparticles were characterized by TEM, FTIR and TGA analyses. The effects of pH and initial nucleoside concentrations on the adsorption behavior were studied. The complexation of CMCD-APTS-MNPs with both nucleosides was found to follow the Langmuir adsorption isotherm. The CMCD-APTS-MNPs showed a higher adsorption ability and selectivity for G than A under identical experimental conditions, which results from the ability of selective binding and recognition of the immobilized CM-β-CD towards G. The driving force of the separation between G and A is through the different weak interaction with grafted CM-β-CD, i.e., hydrogen bond interaction, which is evidenced by different inclusion equilibrium constants and FTIR analyses of inclusion complexes between grafted cyclodextrin and the guest molecules. Our results indicated that this nanoadsorbent would be a promising tool for easy, fast and selective separation, analysis of nucleosides and nucleotides in biological samples.

Surface of magnetic silica nanoparticles is modified by grafting with carboxymethyl-β-cyclodextrin (CM-β-CD) via carbodiimide activation. The functionalized magnetic core–shell nanoparticles (MNPs) are characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infra Red (FTIR) spectroscopy, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Vibrating Sample Magnetometer (VSM). These nano-sized particles are scrutinized for adsorption of certain chiral aromatic amino acid enantiomers namely, d - and l -tryptophan (Trp), d - and l -phenylalanine (Phe) and d - and l -tyrosine (Tyr) from phosphate buffer solutions. Adsorption capacities of the coated magnetic nanoparticles toward amino acid enantiomers are in the order: l -Trp > l -Phe > l -Tyr and under the same condition, adsorption capacities are higher for l -enantiomers than the corresponding d -enantiomers. All the equilibrium adsorption isotherms are fitted well to Freundlich model. FTIR studies depict significant changes after adsorption of amino acids onto nanoparticles. The stretching vibration frequencies of N H bonds of the amino acid molecules are changed with complex formation through host–guest interaction. The structure and hydrophobicity of amino acid molecules emphasize the interactions between amino acid molecules and the nano-adsorbents bearing cyclodextrin, thus play important roles in the difference of their adsorption behaviors.

A novel nano-adsorbent, carboxymethyl-β-cyclodextrin modified Fe(3)O(4) nanoparticles (CMCD-MNPs) is fabricated for removal of copper ions from aqueous solution by grafting CM-β-CD onto the magnetite surface via carbodiimide method. The characteristics results of FTIR, TEM, TGA and XPS show that CM-β-CD is grafted onto Fe(3)O(4) nanoparticles. The grafted CM-β-CD on the Fe(3)O(4) nanoparticles contributes to an enhancement of the adsorption capacity because of the strong abilities of the multiple hydroxyl and carboxyl groups in CM-β-CD to adsorb metal ions. The adsorption of Cu(2+) onto CMCD-MNPs is found to be dependent on pH and temperature. Adsorption equilibrium is achieved in 30 min and the adsorption kinetics of Cu(2+) is found to follow a pseudo-second-order kinetic model. Equilibrium data for Cu(2+) adsorption are fitted well by Langmuir isotherm model. The maximum adsorption capacity for Cu(2+) ions is estimated to be 47.2mg/g at 25 °C. Furthermore, thermodynamic parameters reveal the feasibility, spontaneity and exothermic nature of the adsorption process. FTIR and XPS reveal that Cu(2+) adsorption onto CMCD-MNPs mainly involves the oxygen atoms in CM-β-CD to form surface-complexes. In addition, the copper ions can be desorbed from CMCD-MNPs by citric acid solution with 96.2% desorption efficiency and the CMCD-MNPs exhibit good recyclability.

In this investigation, the drying characteristics of tomatoes have been studied under various operating conditions. A drier was built for experiments under controlled conditions. Experiments were conducted with different air temperatures and flow velocities to determine the drying characteristics of tomato. A diffusion model was used to study the drying of sliced tomato specimens. Shrinkage was observed and this effect was taken into account in the basic diffusion model through the use of a power law expression that related apparent shrinkage to moisture content. Analysis of experimental data yielded correlations between the effective diffusivity and both temperature and air velocity. An equation was also developed to estimate the drying time to reach a particular moisture level.

Proton-induced activation cross-sections were measured for the (89)Y(p,x)(89,88,86)Zr, (89)Y(p,x)(88,87,87 m,86)Y, (89)Y(p,x)(85,83,82)Sr and (89)Y(p,x)(84,83)Rb reactions by a stacked foil technique in the energy range 15-80 MeV which was covered by two separate measurements for 15-50 and 32-80 MeV energy range with 50 and 80 MeV incident protons. The differences between the results of two irradiations were found within 6% in the overlapping energy regions. The production yields for the long-lived products like (88)Zr, and (88)Y are significantly larger than that of (nat)Mo+p, (nat)Nb+p and (nat)Zr+p processes. The productions of the medical isotopes, (85)Sr and (83)Sr are also effective by Y+p process using an 80 MeV beam. Thick target integral yields were also deduced using the measured cross-sections. The (87)Y, (88)Y, (88)Zr and (89)Zr radionuclides have suitable yields and decay characteristics important for thin-layer activation (TLA) analysis.

Magnetic particles about 10 nm in size were prepared by chemical precipitation under nitrogen and used for the selective and sequential adsorption of bovine serum albumin (BSA) (pI = 4.7) and lysozyme (LSZ) (pI = 1.1) under different conditions, such as pH and initial protein concentration. The separation ratio of BSA over LSZ at pH 4.6 is about 5, which is about 1.5 times the separation ratio of LSZ over BSA at pH 11.0. Only 10% of the preadsorbed BSA could be displaced by the sequential adsorption of LSZ at pH 11.0. On the other hand, 60% of the preadsorbed LSZ was desorbed due to the sequential adsorption of BSA at pH 4.6. Over 50% desorption of BSA or LSZ could be achieved either by 0.5 M Na(2)HPO(4) or 0.5 M NaH(2)PO(4) after 2 h. Over 80% of the enzymatic activity of LSZ was preserved when it was desorbed from magnetic particles.

Adsorption and desorption of lysozyme on nano-sized magnetic particles and its conformational change were studied in this work. Adsorption of lysozyme on nano-sized magnetic particles (Fe 3 O 4 ) was carried out at different pH. Maximum adsorption of lysozyme (4.65 mg/m 2 ) occurred at its isoelectric point (p I =11.1). Differential scanning calorimetry (DSC) results show that the lysozyme adsorbed on magnetic particles did not show any thermal transition over the range 20–100 °C. High desorption of lysozyme from magnetic particles was achieved using NaH 2 PO 4 (pH 4.0) (90%) and NaSCN (pH 6.0) (97%) as desorbents. The conformational change of the lysozyme desorbed by NaH 2 PO 4 was small, while the lysozyme desorbed by NaSCN underwent a significant conformational change as measured by the intrinsic fluorescence. Eighty-eight and 82% activity was retained in the desorbed enzyme for desorption by NaH 2 PO 4 and NaSCN, respectively.

Adsorption of bovine serum albumin (BSA) on nanosized magnetic particles (Fe(3)O(4)) was carried out in the presence of carbodiimide. The equilibrium and kinetics of the adsorption process were studied. Nanosized magnetic particles (Fe(3)O(4)) were prepared by the chemical precipitation method using Fe2+, Fe3+ salts, and ammonium hydroxide under a nitrogen atmosphere. Characterizations of magnetic particles were carried out using transmission electron microscopy (TEM) and a vibrating sample magnetometer (VSM). Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to confirm the attachment of BSA on magnetic particles. Effects of pH and salt concentrations were investigated on the adsorption process. The experimental results show that the adsorption of BSA on magnetic particles was affected greatly by the pH, while the effect of salt concentrations was insignificant at a low concentration range. The adsorption equilibrium isotherm was fitted well by the Langmuir model. The maximum adsorption of BSA on magnetic particles occurred at the isoelectric point of BSA. Adsorption kinetics was analyzed by a linear driving force mass-transfer model. BSA was desorbed from magnetic particles under alkaline conditions, which was confirmed by SDS-PAGE electrophoresis and FTIR results.

High level expression of recombinant human tumour necrosis factor beta (rhTNF-beta) in Escherichia coli results in the formation of two portions of protein, namely soluble active protein and insoluble protein which is inactive and aggregates in the form of inclusion bodies (IBs). In this study, a procedure for purification and renaturation of rhTNF-beta from inclusion bodies has been designed and verified experimentally with a product purity of more than 90% and a recovery of about 30%. The procedure includes washing of IBs with specific wash buffer (Triton X-100/EDTA/lysozyme/PMSF), their solubilization with 8 mol dm-3 alkaline urea, purification with ion-exchange columns, refolding with renaturation buffer and finally concentration and desalination with an ultrafiltration membrane. The characteristics of the renatured protein were identical with those of purified protein from the soluble fraction as demonstrated by (1) SDS-PAGE, (2) cytotoxic activity on mouse L929 cells, (3) N-terminal amino acid sequence, and (4) gel filtration chromatography.

Reactive extraction of L-phenylalanine from alkaline aqueous solution into xylene in the presence of tri-octyl-methyl-ammonium chloride (ALIQUAT 336) as complexing agent was studied using a stirred transfer cell. The study investigated the effects of carrier concentration and temperature on mass transfer rates. Transfer rate across the interface in the presence of surfactant molecules was also studied. A two-film model was proposed by considering film mass transfer resistances at the aqueous and organic phases. The model predicted adequately the experimental time-concentration data at different carrier concentrations and temperatures. The model was modified to take into account the presence of surfactant in the organic phase.

Liquid chromatographic techniques have been employed to evaluate the sorption and diffusion characteristics of smaller molecular size amino acids on large zeolite KX-type crystals. The three amino acids investigated in the present study were cysteine, threonine, and serine. All three amino acids adsorbed quite rapidly but there are significant differences in both the equilibrium constants and intracrystalline diffusivities. Combined with the kinetic and equilibrium data of the other three amino acids reported previously, it can be concluded that the larger molecules generally show a lower equilibrium constant. However, no obvious trend can be observed for intracrystalline diffusivity data.

The genetic diversity of a set of hexaploid and tetraploid wheat germplasm at the IPK gene bank, Gatersleben, Germany was investigated by applying 13 wheat microsatellites (WMS). The materials consisted of 63 accessions of Triticum aestivum , T. dicoccon and T. durum obtained from different collection missions. In total, 126 alleles were detected with an average of 9.7 alleles per locus. The average PIC values per locus varied from 0.65 for the marker Xgwm192 to 0.88 for the marker Xgwm619. All the primer pairs revealed genetic heterogeneity in more than one genotype. Genetic dissimilarity values between genotypes, calculated by the WMS derived data, were used to produce a dendrogram. In the dendrogram the genotypes were clustered in nine clear groups. Key words: Genetic diversity, Microsatellite markers, Hexaploid, Tetraploid, Wheat genotype D.O.I. 10.3329/ptcb.v18i1.3267 Plant Tissue Cult. & Biotech. 18 (1): 65-73, 2008 (June)

The adsorption and diffusional kinetics of three macromolecules, namely bovine serum albumin (BSA), transferrin and monoclonal antibody (McAb), on Sephacryl S-200 high resolution gel were studied by the pulse-response chromatographic technique in a column of diameter 1.6 cm and length 8.5 cm. Experimental results showed that the voidage e and axial mixing (2D L /V) in the packed column were 0.432 and 0.05 cm based on the response to a pulse input of blue dextran 2 000 000 and D 2 O solution respectively. The equilibrium constant K and pore diffusivity D p were 0.23 and (0.60 – 1.02) × 10 −7 cm 2 s −1 for BSA (molecular weight, 67 000) 0.17 and (0.62 – 1.0) × 10 −7 cm 2 s −1 for transferrin (molecular weight, 95 000) and 0.095 and (0.53 – 0.85) × 10 −7 cm 2 s −1 for McAb (molecular weight, 150 000 IgG). A van't Hoff plot of ln K vs. 1/T gave a straight line with zero slope and hence zero heat of sorption for all three components. This implies that no adsorption occurs between the molecules and the packing, and that the partition of solute in the bulk solution and pore solution is entirely controlled by diffusional forces.

L'adsorption et la diffusion de quatre aminoacides (glutamine, methionine, phenylalanine, tryptophane) sur un gel de silice poreux sont etudiees par chromatographie

This paper presents a dynamic model which includes axial dispersion and interphase mass transfer for a simulated countercurrent adsorption separation process, together with a numerical technique based on the method of orthogonal collocation for the solution of the governing partial differential equations. It is shown that the experimental transient behavior may be predicted by modeling the system in terms of an equivalent true countercurrent process provided that the inherent limitation of this approach is noted. This approach nonetheless provides a handy tool for predicting the time required for the system to approach quasi-steady state.

Continuous separation of three carbohydrate mixtures [fructose-dextran (M. W. ≈ 9,400), raffinose-dextran (M. W. ≈ 6,000), and fructose-raffinose] has been carried out using a simulated countercurrent process with silica gel as the sorbent and deionized water as the eluent. Experiments were conducted using the commercial four-section arrangement and a modified three-section flow scheme which does not recycle part of the eluent for reuse. Data for the four-section flow scheme reflect a much higher product concentration in the raffinate and a substantially lower rate of fresh eluent consumption than for the three-section scheme. It is concluded that when both the extract and raffinate products are desired, the four-section scheme should be used for the separation of a mixture with a small separation factor which usually requires a large quantity of eluent to achieve an efficient separation. The behavior of the simulated countercurrent process was simulated theoretically by representing the process in terms of an equivalent true countercurrent system. A good fit to the experimental data was obtained when the process was configured in the four-section mode. However, the same theoretical approach failed to provide a good representation of the behavior of the three-section scheme in one respect: predicted concentrations of the raffinate product were about two times higher than experimental values. The discrepancy may be attributed to the periodic switching of fluid inlet and outlet points in the operation of the three-section simulated countercurrent unit.