Batch production of L(+) lactic acid from whey by Lactobacillus casei (NRRL B‐441)

The effects of temperature, pH, and medium composition on lactic acid production by Lactobacillus casei were investigated. The highest lactic acid productivity values were obtained at 37 °C and pH 5.5. The productivity was 1.87 g dm^?3 h^?1 at 37 °C in shake flasks. In the fermenter, a productivity of 3.97 g dm^?3 h^?1 was obtained at pH 5.5. The most appropriate yeast extract concentration was 5.0 g dm^?3. Whey yielded a higher productivity value than the analytical lactose and glucose. Initial whey lactose concentration did not affect lactic acid productivity. MnSO₄ ·H₂O was necessary for lactic acid production by L casei from whey. Product yields were approximately 0.93 g lactic acid g lactose^?1. Copyright © 2004 Society of Chemical Industry     

Application of peptide chromatography for the isolation of antibodies from bovine skim milk,acid whey and colostrum

Protein A mimetic peptide ligands have several benefits over conventional Protein A/G ligands, namely that they are small in size, have low production costs, are stable over a wide range of pH values and can withstand cleaning by harsh sanitization agents such as sodium hydroxide. In this paper, a hexamer peptide (HWRGWV) affinity matrix was used for the isolation of bovine immunoglobulins from various dairy streams (skim milk, acid whey and colostrum). Bound immunoglobulins were recovered in elution buffer (0.2 M sodium acetate buffer, pH 4.0) fractions with a purity of >85% in a single step. The peptide resin has achieved a maximum equilibrium adsorption capacity of 23 ± 0.58 mg mL⁻¹ of resin for bovine IgG and had a dynamic binding capacity of 11.8 ± 0.03 mg mL⁻¹ at residence time of 2 min. These results suggest that the hexamer peptide chromatography could potentially be used for the selective purification of bovine immunoglobulins from dairy streams. This method has promise as an alternative to conventional Protein A/G chromatography for direct capture of immunoglobulins from streams containing relatively high immunoglobulin concentrations such as colostrum, transgenic or hyper-immune milk.     

Batch cultivation of kluyveromyces fragilis in cheese whey

Kluyveromyces fragilis was cultivated batchwise in an open pond rectangular bioreactor at 30°C, 2vvm of aeration, under non-sterile conditions and uncontrolled pH. The culture medium contained 7% cheese whey powder, 0.25% KH₂PO₄, 0.5% (NH₄)₂SO₄ and was adjusted to an initial pH of 4.0 with phosphoric acid. The lactose was almost completely consumed after 16 h and COD reduction attained 80% after 64 h. The maximum suspended solids concentration obtained was 11.7 g/L. The cheese whey which had initially low protein and high lactose contents was converted by this system into a high protein and low lactose carbohydrate product.     

High temperature transformation of pure calcium germanates

The polymorphic transformation of pure 2CaO·GeO₂ and 3CaO·GeO₂ which are the nearest crystal chemical analogous with main cement minerals 2CaO·SiO₂ and 3CaO·SiO₂ has been studied by X-ray diffraction. X-ray patterns of the polymorphic forms of the 3CaO·GeO₂ were obtained at ambient temperature, 820°C and 1410°C. The fragments of X-ray pattern of unstable modification were obtained at 1060°C. X-ray diffraction patterns of the modification of the 2CaO·GeO₂ were received at ambient temperature and 1480°C. The lattices constants of the modifications of pure 3CaO·GeO₂ and 2CaO·GeO₂ are given.     

The S···P noncovalent interaction: diverse chalcogen bonds

The S···P interactions in the complexes of HSX (X?=?F, Cl, Br, I) with PH_nMe_3-n(n?=?0–3) have been investigated with ab initio calculations at the MP2/aug-cc-pVDZ and MP2/aug-cc-pVTZ//MP2/aug-cc-pVDZ level of theory. The interaction energies and structural properties of intermolecular complexes have been analyzed. Results of QTAIM analysis are dealing with expand of interactions, including pure closed-shell interactions (van der Waals interactions and chalcogen bonding, YB), partially covalent closed-shell (CS; Charge Transfer) and shared-shell interactions (SS; weak covalent bond and very strong YB) for these complexes. The energy decomposition analysis (EDA) showed that electrostatic interactions are an important contributing factor for these complexes. In considering second-order contributions, the donor-acceptor pair charge transfer (CT) is most important. These findings are consistent with the Electron Localization Function (ELF) isosurface of the complexes. In each series of HXS:PH_nMe_3-n-chalcogen bond complexes with increasing basicity of phosphines, the stability and S···P bond strength of adducts were increased so that the HXS:PMe₃ (X?=?F, Cl, Br) complexes had very strong S···P chalcogen interactions with nearly covalent characters.     

CuCN and Trimethylsilyl Chloride-Catalyzed Regiospecific Grignard Reactions to CF3-Containing Allylic Derivatives

CF₃-containing allylic alcohol derivatives were treated with an appropriate Grignard reagent in the presence of catalytic amounts of CuCN and trimethylsilyl chloride (TMSCl) to furnish products via the clean anti-S_N2′ mechanism. Experimental results as well as ab initio computational analyses unambiguously demonstrated the important roles of TMSCl as a Lewis basic additive for smooth promotion of reductive elimination and inhibition of the “Cu···F” elimination leading to undesired byproduct formation.     

Novel Copper(II) Complexes of <Emphasis Type="Italic">N</Emphasis>-Phenylanthranilic Acid Containing Ethanol and Hydroxo Ligands

The complexes, tetra-μ-[2-(phenylamino)benzoato](O,O′)-bis[(ethanol)copper(II)] (1) and di-μ-[2-(phenylamino)benzoato](O,O′)-bis[(hydroxo)copper(II)] (2), were synthesized by the reaction of N-phenylanthranilic acid and CuCl₂·2H₂O in an ethanol water mixture. In complex 1, each Cu(II) atom, which is in a slightly distorted square pyramidal environment, is coordinated equatorially by four N-phenylanthranilate O-atoms and axially by the ethanol O-atoms. In complex 2, [Cu₂(C₆H₅NHC₆H₄COO)₂(OH)₂], each Cu(II) atom, which is in tetrahedral environment, is coordinated by two N-phenylanthranilate O-atoms and hydroxo ligands. The crystal structure (monoclinic, P21/c space group) of complex 1 comprises a dinuclear [Cu₂(C₆H₅NHC₆H₄COO)₄(CH₃CH₂OH)₂] species and the dimer is located on a crystallographic inversion centre. The Cu(II) ions, 2.591(2) Å apart, are bridged by the carboxylate groups of four N-phenylanthranilate ligands. The complex molecules show three-dimensional supramolecular networks by O–H···O, C–H···O and C–H···π interactions.     

Alkaline hydrolysis of alkylated acidic groups on carbon black

Potentiometric pH-stat titration was performed on alkylated carbon black dispersed in aqueous solution at pH 9.0, 10.0 and 11.0 and alkaline hydrolysis rate constant of the alkylated functional groups on the carbon black was obtained therefrom. Carbon black treated with C₁-C₈n-alcohols in vapor or liquid phase was used in this experiment. Hydrolysis proceeded more rapidly for carbon black treated with lower alcohols. For each alkylated carbon black, the hydrolysis rate constant decreased with time and, after the hydrolysis rate diminished, a hydrolysis resistant fraction of alkylated groups remained. For example, the hydrolysis rate constants at 25°C were 24.33, 17.50 and 4.501 · mol^?1 · sec^?1 at 15 min and 6.00, 6.00 and 3.671 · mol^?1 · sec^?1 at 45 min after the start of hydrolysis at pH 9.0 for carbon black treated with C₂, C₃ and C₄ alcohols respectively.     

Effect of processing parameters on the morphology of hydrothermally synthesized calcium borate powders

The present study aimed to examine the effect of pH and time on the final morphology of calcium borate powders. Primarily, aqueous solutions that mainly consisted of borax and calcium chloride were prepared with five different pH values varying between 2 and 15. Hydrothermal synthesis temperature was determined as 200°C, and four different times from 30 min to 24 h were selected. Phase formation and powder morphology were examined via an X-ray diffractometer and scanning electron microscopy. Fourier transform infrared spectroscopy was used to identify the type of borate groups. Results revealed that pH directly determines the growth mechanism of calcium borate crystals. Lower pH induced nonclassical growth by forming self-assembled nano-plates. Individual, rodlike particles were observed for alkali solution. At weak basic conditions, priceite (4CaO·5B₂O₃·7H₂O) and alkali condition parasibirskite (2CaO·B₂O₃·H₂O) phases were obtained.     

Comparison of β-galactosidase immobilization by entrapment in and adsorption on poly(2-hydroxyethylmethacrylate) membranes

β-Galactosidase was immobilized in/on poly(2-hydroxyethyl methacrylate) (pHEMA) membranes by two different methods: adsorption on Cibacron F3GA derivatized pHEMA membranes (pHEMA-CB), and entrapment in the bulk of the pHEMA membranes. The maximum β-galactosidase adsorption on pHEMA-CB membranes was obtained as 95·6μgcm^-2 in 2·0mgcm^-3 enzyme solution. The adsorption phenomena appeared to follow a typical Langmuir isotherm. In the entrapment, an increase in β-galactosidase loading resulted in a consistent increase in membrane activity from 3·3×10^-2 to 17·8×10^-2Ucm^-2 pHEMA membranes. The K_m values for both immobilized β-galactosidase (adsorbed 0·32mM and entrapped 0·81mM ) were higher than that of the free enzyme (0·26mM ). The optimum reaction temperature of the adsorbed enzyme was 5°C higher than that of both the free and the entrapped enzyme. The optimum reaction pH was 7·5 for free and both immobilized preparations. After 15 successive uses the retained activity of the adsorbed and the entrapped enzymes was 80% and 95%, respectively. The storage stability of the enzyme was found to increase upon immobilization. ©1997 SCI     

Reverse osmosis applied to the recovery of water from aqueous salt solutions

A cellulose acetate membrane was applied to the study of reverse osmosis on aqueous solutions of LiCl, NaCl, KCl, CaCl₂, SrCl₂ and BaCl₂. This membrane, 71 microns thick and having an effective diameter of 1 1/2 in. was mounted within a specially constructed cell, made of stainless steel and designed to withstand pressures up to 1500 psi. The cell consisted of two chambers, which were separated by the membrane, and a porous plate supporting it. Solutions of 0·05 N, for all of these salts, were used to establish the osmotic pressure of each solution, the water fluxes through the membrane, and the extent of salt rejection. These variables were also determined for NaCl normalities of 0·2 and 0·6. On a single pass basis, the salt rejections ranged from 76% for KCl up to 95% for CaCl₂. The results are discussed in terms of the size of the hydrated cation. The water fluxes for all these solutions were found to be essentially the same and were independent of the type of salt. For solutions of 0·05 N, the water fluxes ranged from zero at the osmotic pressure up to about 44 × 10^?5 g sec^?1cm^?2 (8·8 gal day^?1ft^?2) at 800 psi and 77°F. Also, for the 0·05 N-NaCl solution, the temperature was varied from 77°F to 120°F. The results of this temperature study show that the extent of salt rejection remains essentially fixed, while the water flux at any given pressure at 120°F becomes nearly double that of 77°F.     

Studies of anodic dissolution and film growth on iron in acid chloride solutions

The rate of dissolution of Armco Fe has been measured as a function of time for deaerated solutions of constant ionic strength (HCl + NaCl).For pH < 1·5, no appreciable change of the measured polarisation resistance was observed. For 1·5 < pH < 3 the polarisation resistance gave straight lines when plotted against time. The slope of the lines is represented by a = 2·0√(C_OH^?.10¹⁴ ? 45) Ωcm²/min, where C_OH^? is the concentration of the bulk.The Tafel slopes were 64–70 mV when 0 < pH < 1·2.The experimental data are explained by two very similar reaction mechanisms. The theory presented involves the formation of two surface complexes denoted by FeOH Fe·H₂O and FeO Fe·H₂O. It is suggested that the complex FeOH Fe·H₂O serves as nuclei for film formation when pH > 1·5. This would explain the change of the reaction mechanism at pH = 1·5 from a 60 mV mechanism when pH < 1·5 to a 30 mV mechanism when pH > 1·5.The theory is supported by data from the literature. It gives a reasonable explanation of the nonstationary 60 mV Tafel slopes. The mechanisms are in harmony with a hyperbolic relation between anodic current density and time. The logarithmic law of film growth may be derived from the same principles.     

PRECIPITATION CONDITIONS OF CHEVREUL'S SALT FROM SYNTHETIC AQUEOUS CuSO4 SOLUTIONS

In this study, synthetic aqueous CuSO₄ solution was prepared at various concentrations. Chevreul's salt was precipitated by passing SO₂ through these solutions. Chevreul's salt, a mixed valence copper sulfite, Cu₂SO₃·CuSO₃·2H₂O, was characterized by XRD and SEM. The effects of parameters such as initial solution concentration, SO₂ feeding rate, reaction time, and initial solution pH on precipitation of Chevreul's salt were investigated. 2ⁿ factorial experimental design and orthogonal central composite design methods in the precipitation experiments were used. It was observed that the effective parameters on the precipitation of Chevreul's salt were initial solution concentration, SO₂ feeding rate, and initial solution pH. The optimum conditions obtained for maximum copper precipitation were: initial solution concentration 1.14 M, SO₂ feeding rate 329.35 L.h.^?1, reaction time 25 min, and initial solution pH 8.5. Constant parameters chosen at the initial stage of the reaction were: temperature 62°C, stirring speed 600 rpm, and reaction pH 3 (Çalban et al., 2006). Under these optimum conditions, the percentage of precipitated copper from synthetic aqueous CuSO₄ solutions was 99.95.     

The transformation: Brushite → calcium monofluorophosphate under aqueous conditions

The reaction between CaHPO₄. 2H₂O and 10^?1 M solution of Na₂PO₃F have been studied in the pH range 7 to 5 at 25 °C. The formation of CaPO₃F · 2H₂O, rather than CaF₂ or Ca₅F (PO₄)₃ by initial hydrolysis and subsequent reaction with the F^? formed, appeared to occur. The value of ΔG for CaPO₃F · 2H₂O has been calculated as – 530.9 kcal mol^?1. A comparison is drawn to the exchange reactions reported here, and to the similar reactions reported to occur in calcium deficient apatite.     

Studies on glass transition temperature of mono and bilayer protein films plasticized by glycerol and olive oil

Thermomechanical and thermal properties of whey protein, maize prolamin protein (zein), and the laminated whey protein–zein films were studied. The dynamic mechanical (thermal) analysis (DMTA) results showed that the single zein film had higher T_g than single whey protein and zein–whey laminated films. The shift in the T_g values of films from 31.2°C in whey protein film and 88.5°C in the zein film to 82.8°C in the laminated whey protein–zein films may be implied some interaction formation between the two polymers. The small tan δ peaks were observed at ?50°C in zein–glycerol films and at ?22.37°C in the whey protein films and can be related to β‐relaxation phenomena or presence of glycerol rich region in polymer matrix. Zein‐olive oil and zein–whey protein–olive oil films showed tan δ peaks corresponded the T_g values at 113.8, and 92.4°C, respectively. Thus, replacing of glycerol with olive oil in film composition increased T_g. A good correspondence was obtained when DSC results were compared with the tan δ peaks in DMTA measurements. DSC thermograms suggested that plasticizers and biopolymers remained a homogeneous material throughout the cooling and heating cycle. The results showed that T_g of zein–glycerol films predicted by Couchman and Karasz equation is very close to value obtained by DSC experiments. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polarographic reduction of benzoylacetanilides,mechanism and structure-reactivity relationships

The electroreduction of a series of substituted benzoylacetanilides (I) on a dme was investigated in ethanolic Britton—Robinson buffers, and the overall dissociation constants K* of I were evaluated spectrophotometrically under similar conditions. The polarographic curves showed in each case one, two electron cathodic wave, which corresponds to the reduction of the protonated keto form of I. From the pH dependence of the limiting current, the apparent polarographic K′ constants that depend on the protonation of I were determined. Values of the acid dissociation constants of the keto (K₁) and enol (K₂ tautomers of I were deduced. The values of E_{$\text{1}\text{2}$}, pK* and pK₁ were shown to be linear functions of Hammett substituent constants. The equations of the regression lines obtained are: E_{$\text{1}\text{2}$} = 0·284σ—1·379 (r = 0·990) at pH 8·0; pK* = 9·54–2·71σ, (r = 0·998); and pK₁ = 9·45–2·946σ, (r = 0·954), respectively. Correlation of pK₂ values with substituent constants showed a break at about σ = 0. Controlled potential electrolysis of benzoylacetanilide (Id) produces 3-phenyl-3-hydroxypropionanilide (IIId). A mechanism for the polarographic reduction of I is proposed.     

Influence of the Initial pH on the adsorption behaviour of dispersant on nano zirconia powder

The quantitative adsorption behaviour of ammonium salt of poly(acrylic acid) onto zirconia powder in aqueous solution is characterized by using UV adsorption spectrum. Adsorption isotherms of dispersant on the zirconia surface, electrophoretic mobility of zirconia particles as a function of the dispersant concentration have been investigated. The adsorption behaviour of PAA-NH₄ is dependent on the pH of the suspension and the concentration of the ammonium salt of poly(acrylic acid). The maximum amount of PAA-NH₄ adsorbed on the zirconia surface, 6·3 mg m⁻² at pH 2·62, decreases to 2·1 mg m⁻² at pH 12·20. The adsorption of PAA-NH₄ causes a highly negatively charged powder surface and almost same final pH value.     

Oxidation of Esculetin,a Model Pollutant Present in Cork Processing Wastewaters,by Chemical Methods

The ozonation of esculetin (6,7-dihydroxycoumarin), a major pollutant present in the wastewater generated in the cork industry, was accelerated at high pH, with apparent second-order rate constants in the range from 3.3 × 10⁴ L/(mol·s) at pH=2 to 8.4 × 10⁷ L/(mol·s) at pH=9. The acid-base equilibrium of esculetin was studied, resulting in a pK_a value of 7.37. Taking into account this pK_a, the rate constants for the reaction between ozone and the un dissociated and dissociated forms of esculetin were 3.0 × 10⁴ and L/(mol·s) 6.67 × 10⁸ L/(mol·s), respectively. Apparent first-order rate constants for the photolysis by UV irradiation were also evaluated, with values between 0.12 × 10^?2 min^?1 at pH=2 and 1.15 × 10^?2 min^?1 at pH=9, while the quantum yields for this photo-degradation reaction varied from 0.99 × 10^?2 mol/Eins to 11.1 × 10^?2 mol/Eins at these pHs. The Fenton's reagent system was used for the generation of hydroxyl radicals, and the rate constant for the reaction between esculetin and these radicals was determined to be 1.06 × 10¹⁰ L/(mol·s). Finally, several chemical oxidation systems were used in the degradation of this pollutant: single oxidants (ozone, UV irradiation) and advanced oxidation processes (Fenton's reagent, UV/H₂O₂, O₃/H₂O₂, O₃/UV, O₃/H₂O₂ /UV, and photo-Fenton system). The results revealed that the most efficient methods in terms of esculetin removal were ozonation among the single oxidants, and the photo-Fenton system among the combined processes.     

Non-ionizable Polyacrylic Hydrogels Sensitive to pH for Biomedical Applications

Hydrogels based on ethoxytriethyleneglycol monomethacrylate/methyl methacrylate (T/M) copolymers were prepared by free radical polymerization at 70°C in bulk with azobisisobutyronitrile as initiator. The reactivity ratios were calculated by Fineman–Ross (FR) and Kelen–Tudos (KT) linearization methods and by the non-linear least square method suggested by Tidwell and Mortimer (TM). The reactivity ratios obtained were r_T=0·17±0·03, r_M=0·70±0·01 (FR method); r_T=0·19±0·02, r_M=0·76±0·03 (KT method) and r_T=0·18; r_M= 0·75 (TM method). Microstructure was obtained in terms of the distribution of T- and M-centred triads. The swelling behaviour of the hydrogels was studied by immersion of the films in water and in buffered solutions at various pH values and it was analysed by comparison with that of poly(ethoxytriethyleneglycol monomethacrylate). It was observed that not only the average copolymer composition but also the distribution of monomeric sequences play an important role in the swelling behaviour. © 1997 SCI.     

Effects of various factors on capacitive properties of VO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>·<Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O powders in aqueous electrolyte

In this work, effects of drying temperature, pH of aqueous electrolyte and current density on capacitive performance of VO _x ·nH₂O material were firstly investigated. VO _x ·nH₂O powders were prepared by a melt quenching method. The samples were characterized by X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR). The capacitive properties of VO _x ·nH₂O samples were examined by cyclic voltammetry and galvanostatic charge/discharge test. VO _x ·nH₂O sample which was obtained at the drying temperature of 80 °C, delivers a maximum specific capacitance of 227.3 F g⁻¹ and exhibits excellent capacity retention in the potential range of −0.3 to 0.7 V at a current density of 200 mA g⁻¹ in NaNO₃ solution with pH 2.