Acid-treated Product Research Articles

Elaboration, characterization and performance evaluation of a new environmentally friendly adsorbent material based on the reed filter (Typha Latifolia): Kinetic and thermodynamic studies and application in the adsorption of Cd (II) ion

• The kinetic study, at constant temperature, shows that the extraction yield and the sorption capacity of Cd (II) on the resin increase rapidly with time, the equilibrium is reached after 40 min for raw reeds (RB) and 60 min for treated reeds (RS). • The adsorption capacity increases with the increase of the initial cadmium concentration and reaches a maximum equal to mg g −1 at a concentration higher or equal to 26.35 mg g −1 and 40.01 mg g −1 , respectively for RB and RS. • This retention capacity is very important which shows that this resin has a high affinity towards cadmium. • The application of the Langmuir and Freundlich adsorption models showed that the Langmuir isotherm better describes the adsorption of Cd (II) on the resin. Heavy metal pollution is a public health problem that should prompt environmental protection authorities to provide appropriate solutions. The objective of this work concerns the liquid-solid extraction of Cadmium by the filtering resin of raw RB and modified RS reeds. The experimental study clarified the influence of some operating parameters. The results of the experiments show that the adsorption process depends on several parameters: the presence of salts, the temperature and the pH of the medium. Equilibrium is reached after 40 min for raw reeds (RB) and 60 min for treated reeds (RS). The pH of the aqueous phase, optimal for this extraction is between 4.5 and 6.0, increasing the temperature of the aqueous phase-adsorbate mixture from 25 to 65 °C decreases the extraction yield and the sorption capacity. The pseudo-second order kinetic model and Langmuir model are the most adequate to describe the adsorption process and the adsorption capacity increases with the increase of initial cadmium. Concentration and reaches a maximum equal to 26.35 mg g −1 and 40.01 mg g −1 , respectively for RB and RS. The thermodynamic study showed that the retention process is spontaneous and exothermic. The cadmium metal Cd (II) adsorption mechanism was also interpreted by spectroscopy FTIR and energy-dispersive X-ray (EDX). Dramatically, the introduction of the chemical treatment allows the increase of the content of activated functional groups in the resin, leading to a higher amount of adsorption on Cd (II). The desorption might of the resin depended on the various parameters like HNO 3 concentration, desorption of the temperature and time. The satisfactory desorption of the capacity and efficiency is 69% RB and 92% RS. Based on these results, RB and RS acid-treated products could be utilized as low-cost, environmentally friendly and effective adsorbents for Cd (II) elimination from water. The various parameters thermodynamic such as ∆G°, ∆S° and ∆H° showed that the adsorption process was feasible, spontaneous and exothermic.

Preparation and Characterization of Activated Sericite Modified by Fluorosilicate and Acid

Although sericite belongs to 2:1 clay minerals, it hardly has intercalation properties because it has high layer charge density, which produces pretty strong electrostatic force. Therefore, the purpose of activation is to permanently reduce the layer charge of sericite and obtain numbers of exchangeable cations. The original sericite (S0) was sintered at 800 °C for 1 h. After that, thermal-treated sericite (S1) was activated with sodium fluosilicate and nitric acid, whose effects were characterized by X-ray diffraction (XRD) analysis, chemical analysis and zeta electric potential analysis. The dissolving-out amount of Al3+ of acid-treated product (S2) reached circa 65 mg/g at the optimal processing conditions. After sodium modification with NaCl, CEC of final resulting product (S3) was increased to 14.34 meq/100g compared with that of original sericite (4.94 meq/100g). The results of chemical analysis and zeta electric potential analysis indicated that acid activation with sodium fluosilicate and nitric acid decreased the layer charge of sericite.

Fabrication process of intrinsic Josephson junction stacks in Bi2Sr2CaCu2O8+x crystals by double-sided patterning process using dilute hydrochloric acid

We have developed a new double-sided patterning (DSP) process that employs dilute acid (pH=1.65) to fabricate Bi2Sr2CaCu2O8+x (Bi-2212) stacks of intrinsic Josephson junctions. These stacks, which were fabricated from a single crystal of Bi-2212, were surrounded by an acid-treated product. The critical aspect of this process is that the Bi-2212 surrounding the photoresist pattern was converted into a transparent material, BiOCl, which was connected with the Bi-2212 crystal. Consequently, this process provides a simple way to achieve DSP of the surfaces of Bi-2212 crystals. This new DSP process realizes a remarkably improved reproducibility in fabricating Bi-2212 stacks that exhibit good current–voltage characteristics with a large hysteresis and multiple branches at T=77K.

Fabrication of a ${\rm Bi}_{2}{\rm Sr}_{2}{\rm CaCu}_{2}{\rm O}_{8+x}$ Intrinsic DC-SQUID With a Shunt Resistor

We fabricated Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> CaCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> (Bi-2212) SQUIDs with two stacks of intrinsic Josephson junctions by an acid-treatment process. The stacks were fabricated from a single crystal of Bi-2212. The in-plane loop of a dc-SQUID was surrounded by an acid-treated product, which was produced by immersing the Bi-2212 single crystal in dilute hydrochloric acid (pH=1.65). The critical aspect of this process is that the surrounding acid-treated product (BiOCl) is transparent. The SQUID exhibited a large hysteresis with a ratio of the critical current to the return current of 0.4 at 77 K. Applying a magnetic field modulated the critical current of a dc-SQUID for fields of up to about 10 G. In addition, we fabricated dc-SQUIDs attached to a shunt resistor, which exhibited nonhysteretic current-voltage characteristics. Appling a magnetic field modulated the voltage; the maximum voltage modulation was about 30 μV at 77 K.

Characterization of ${\rm Bi}_{2}{\rm Sr}_{2}{\rm CaCu}_{2}{\rm O}_{8+\delta}$ Stacks Fabricated by Acid Treatment Process

Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> CaCu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8+δ</sub> (Bi-2212) stacks of intrinsic Josephson junctions were fabricated by an acid-treatment process from inside a single crystal. The surrounding acid-treated product is a transparent material, BiOCl. During the process, an optical adhesive (NOA-61) was used to fix a piece of the crystal on a glass substrate and to coat the surface of the sample. The current-voltage characteristics of the stacks at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> = 77 K exhibited large hystereses and multiple branches with voltage spacings of approximately 2-3 mV. Under an external microwave field in the frequency range of 2-18 GHz, clear Shapiro steps were observed at voltages with multiples of ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</i> /2 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> ) <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rf</sub> . In addition, the thermal cycling properties of the critical current ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) were investigated. No apparent degradation of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> was observed during repeated thermal cycling between 300 and 77 K.

Three-dimensional porous metal–organic replica of natural mineral α-Al2O3 based on hexadentate triazine derivative

Abstract A non-interpenetrated 3D porous metal–organic framework [(CH3)2NH2]2[Cd(TATAT)2/3]·4DMF (1) (TATAT = 5,5′,5″-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)triisophthalate) has been successfully synthesized under solvothermal conditions and characterized by elemental analysis, TGA, and single-crystal X-ray diffraction analysis. Compound 1 exhibits α-Al2O3 (corundum) topology and represents the first metal–organic analog presently known with a natural material topology based on 6-connected organic ligand and tetrahedral metal ion. In addition, the thermal stabilities of the complex and the acid-treated product have been investigated and the results indicate that acid treatment is an efficient way for this compound to improve its thermal stability.

New Double-sided Patterning Process Using a Dilute Hydrochloric Acid Solution to Fabricate Stacked Intrinsic Josephson Junctions Inside Bi2Sr2CaCu2O8+x Single Crystals

We developed a new double-sided patterning (DSP) process using a dilute acid solution (pH=1.65) to fabricate Bi2Sr2CaCu2O8+x (Bi-2212) stacks of intrinsic Josephson junctions. The stacks, which were fabricated from a single crystal of Bi-2212, were surrounded by an acid-treated product. The critical aspect of this process is that the Bi-2212 surrounding the photo-resist pattern was changed to a transparent material, BiOCl, which was connected with the Bi-2212 crystal. As a result, this process provides an easy way to achieve the DSP of the surface of the Bi-2212 crystal. This new DSP process allows for remarkably improved reproducibility in fabricating the Bi-2212 stacks which show good current-voltage characteristics with large hysteresis and multiple branches at T=77 K.

Characterization of Bi 5Nb 3O 15 by refinement of neutron diffraction pattern, acid treatment and reaction of the acid-treated product with n-alkylamines

The structure of Bi 5Nb 3O 15 was investigated by refinement of the powder neutron diffraction pattern as well as by structural change through acid treatment and subsequent treatments of an acid-treated product with n-alkylamines. Rietveld refinement suggests that Bi 5Nb 3O 15 adopts a mixed-layer Aurivillius-related phase structure, [Bi 2O 2]+[NbO 4]+[Bi 2O 2]+[BiNb 2O 7] [ Pnc2 (space group No. 30)] with a = 2.1011 ( 4 ) , b = 0.5473 ( 1 ) and c = 0.5463 ( 1 ) nm. After the acid treatment of Bi 5Nb 3O 15 with 3 mol/L HCl, a new reflection (at 2.25 nm after drying at room temperature or at 1.89 nm after drying at 120 °C) appeared in the X-ray diffraction (XRD) pattern in addition to the reflections due to Bi 5Nb 3O 15. Upon acid treatment, a part of the Bi ions were lost and essentially no Nb ions were dissolved during acid treatment to give a Bi/Nb molar ratio of 1.4. The TG curves of the acid-treated product showed mass loss (ca. 4 mass%) in the range of 300–600 °C. It was also demonstrated that the particle shapes did not change upon acid treatment. The reaction of the acid-treated product (after drying at room temperature) with n-alkylamines led to a shift of the newly appearing reflection to a lower angle, and the d-value of the low-angle reflection increased linearly in accordance with the increment of the number of carbon atoms in n-alkylamines. These results indicate that the [Bi 2O 2] sheet in Bi 5Nb 3O 15 was partially leached by acid treatment to form a layered compound H 4BiNb 3O 11· xH 2O, capable of accommodating n-alkylamines in the interlayer space, and its anhydrous form, H 4BiNb 3O 11, upon drying. Based on the variation in the interlayer distance upon intercalation of n-alkylamines into the acid-treated product, the structure of the acid-treated product can be suggested to comprise alternately stacked protonated [BiNb 2O 7] and [NbO 4] sheets, a result consistent with the Rietveld refinement of Bi 5Nb 3O 15.

CONCENTRATED ACID CONVERSION OF PINE SOFTWOOD TO SUGARS. PART I: USE OF A TWIN-SCREW REACTOR FOR HYDROLYSIS PRETREATMENT

The first stage of a two-step concentrated sulfuric acid process that converts softwood sawdust to sugars has been explored. The research focuses on the ability of an in-house custom fabricated corotating twin-screw reactor (TSR) to effectively break down and solubilize crystalline cellulose into low molecular weight carbohydrates. Based on design of experiment (DOE) screening results, a four-level, two-factor experimental model building DOE was undertaken. Solid sawdust conversion to liquid, screw torque, and TSR exit pressure were measured or recorded at each experimental condition to yield percent conversion of solids, processed material viscosity, and material energy requirements. Thereafter, model quadratic equations were fitted to the experimental data and found to be statistically significant. Based on data obtained in the DOE the process was optimized to establish a base case operating condition. The acid-treated product made at base case twin-screw operating conditions showed a 38.2% conversion of dry sawdust solids to soluble liquids. The dry solids conversion reduced 73.8% of all hemicellulose and 44.4% of all cellulose to soluble monomers and oligosaccharides.

A layered tungstic acid H2W2O7 x nH2O with a double-octahedral sheet structure: conversion process from an aurivillius phase Bi2W2O9 and structural characterization.

The conversion process of an Aurivillius phase, Bi(2)W(2)O(9), into a layered tungstic acid by hydrochloric acid treatment has been investigated, and resultant H(2)W(2)O(7) x nH(2)O has been fully characterized. The c parameter of Bi(2)W(2)O(9) [2.37063(5) nm] decreases to 2.21(1) nm in an acid-treated product dried at ambient temperature. The a and b parameters of Bi(2)W(2)O(9) [a = 0.54377(1) nm and b = 0.54166(1) nm] also decrease slightly to a = 0.524(1) nm and b = 0.513(1) nm in the acid-treated product dried at ambient temperature, indicating structural changes in the ReO(3)-like slabs in Bi(2)W(2)O(9) upon acid treatment. Drying at 120 degrees C leads to a further decrease in the c parameter [1.86(1) nm] with no notable change in the a and b parameters [a = 0.5249(2) nm and b = 0.513(2) nm]. The formation of an expandable layered structure is demonstrated by the successful intercalation of n-octylamine [interlayer distance 2.597(9) nm] and n-dodecylamine [interlayer distance 3.56(2) nm]. The compositions of the acid-treated products are determined to be H(2)W(2)O(7) x nH(2)O typically with n = 0.58 for the air-dried product and n = 0 for the product dried at 120 degrees C. As a consequence, the composition of the layer is H(2)W(2)O(7), and the decrease in the c parameter upon drying is ascribable to the loss of interlayer water. Scanning electron microscopy reveals no morphological change during acid treatment, which strongly suggests a selective leaching of the bismuth oxide sheets as a reaction mechanism. High-resolution transmission electron microscopy (HREM) observation of the acid-treated product shows consistency with a structural model for H(2)W(2)O(7), derived from Bi(2)W(2)O(9) through removal of the bismuth oxide sheets and contraction along the c axis. HREM observation also reveals that the WO(6) octahedra arrangement changes slightly with acid treatment. A one-dimensional electron density map projected on the c axis for the product dried at 120 degrees C, H(2)W(2)O(7), shows good consistency with that calculated for the structural model.

Conversion of Aurivillius Phases Bi2ANaNb3O12 (A: Sr or Ca) into the Protonated Forms of Layered Perovskite via Acid Treatment.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Conversion of Aurivillius Phases Bi2ANaNb3O12(A = Sr or Ca) into the Protonated Forms of Layered Perovskite via Acid Treatment

Protonated forms of layered perovskites were derived from Aurivillius phases, Bi2ANaNb3O12 (A = Sr or Ca), by the substitution of bismuth oxide sheets with protons via acid treatment. The conversion into the protonated forms was achieved easily using 6 M HCl at room temperature. Preservation of the structure of the perovskite-like slabs and contraction in the c axis were confirmed by X-ray and electron diffraction analysis as well as by transmission electron microscopy. The compositions of the resulting products were determined to be H1.8[A0.8Bi0.2NaNb3O10] (A = Sr or Ca) by inductively coupled plasma emission spectroscopy and thermogravimetry. The acid-treated product H1.8[Sr0.8Bi0.2NaNb3O10] was capable of accommodating n-alkylamines in the interlayer space, which is in good agreement with the proposed layered structure.

Structural and Thermal Characteristics of Nickel Dioxide Derived from LiNiO2

We report the structural and thermal characteristics of highly delithiated (lithium extracted) compounds LixNiO2, which can be called “nickel dioxide.” We obtained Li0.10NiO2 and Li0.04NiO2 by treating LiNiO2 with sulfuric acid. Both products contained phases with NiO2 stacking similar to cadmium chloride (O3-type), but the latter also included a phase with NiO2 stacking similar to cadmium iodide (O1-type). We examined their thermal behavior using high temperature X-ray diffraction analysis together with thermogravimetric analysis and found that novel polymorphs, with similar chemical compositions but different structures, were obtained by heating them at appropriate temperatures. We discuss these results together with those for LixNiO2 obtained by electrochemical delithiation. We also report acid-treated products derived from Li0.93Ni1.07O2.

Micropore Formation by Acid Treatment of Antigorite

Microporous materials are prepared by H{sub 2}SO{sub 4} treatment of antigorite (Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}) and characterized mainly by SEM observation, a gas adsorption method, and {sup 29}Si MAS NMR spectroscopy. The microtexture of the acid-treated products retains the morphology of the original pore composed of antigorite-like platy masses. Micropores 1 nm in size are formed between the layers of SiO{sub 4}-tetrahedron by Mg{sup 2+} dissolution. The micropore structure is changed by a condensation of silanol groups occurring in the pores. The maximum specific surface area is around 400 m{sup 2}/g, pore volume is 0.22 mL/g, and mean pore diameter is 1.2 nm. Around 5% MgO is necessary to stabilize the micropore structure and achieve a specific surface area of over 300 m{sup 2}/g. Mg{sup 2+} dissolution finally leads to formation of an amorphous silica with more than 99% SiO{sub 2} content of which the specific surface area, pore volume and mean pore diameter are 170 m{sup 2}/g, 0.08 mL/g, and 2.0 nm, respectively. 10 refs., 10 figs., 1 tab.

Mutagenecity and contents of polycyclic aromatic hydrocarbons in new high-viscosity naphthenic oils and used and recycled mineral oils

Mutagenic activity on the Ames test was evaluated in 15 samples of naphthenic high-viscosity minerals oils and 12 samples of used lubricants (recovered and pooled) and their recycled products. Bacterial mutagenesis was assayed using both the standard technique and Blackburn's modification. The contents of polycyclic aromatic hydrocarbons (PAH) was also evaluated, as polynuclear aromatic fraction (PAF) and total PAH, determined respectively with the semi-quantitative dimethylsulphoxide-refractive index method and the Grimmer method. Only four samples (three acid-treated naphthenic oils and one recycled fraction of a used oil) showed mutagenic activity higher than 6 revertants/mg of oil, considered by Blackburn and coworkers as indicating a potential carcinogenic risk for these compounds. Limited mutagenecity was found in all used and recycled oils, but also in samples of acid- or solvent-treated oils. No hydrogen-treated naphthenic oils turned out to have any mutagenic activity. PAF contents of oils were closely correlated with those of total PAH ( n = 15, r = 0.83; n = 12, r = 0.91; p<0.01 for both naphthenic and used/recycled oils respectively). No recycled oil had high PAF contents. Eleven samples had PAF contents higher than 3%, the arbitrary danger threshold suggested by the CONCAWE (1988). Of these 11 samples, the majority were acid-treated products, although there was one hydrogen-treated oil and one used and recycled oil. No mutagenic activity could be demonstrated in almost half the oils with PAF > 3%. In this study, the presence of mutagens was not correlated either with PAF or with total or mutagenic PAH. The difficulty of predicting the mutagenecity of mineral oil is stressed. Most naphthenic and some recycled oils clearly have components which inhibit the metabolizing system in the bacterial mutagenesis test, with consequent possible false negative results.

Pore structure characterization of kaolin, metakaolin, and their acid-treated products using small-angle X-ray scattering

Pore structure of dealuminated kaolin and metakaolin was studied by small-angle X-ray scattering (SAXS). Both parent kaolin and metakaolin have about 10% of the total pore volume provided by globular pores with 105 Å mean pore size. Their surface area is about 14 m 2/g. Acid dealumination of kaolin causes an increase of its globular pore volume without an appreciable change in the mean pore size, its surface area increasing up to about 90 m 2/g. Acid dealumination of metakaolin enhances the globular pore volume, although there is generation of slit-shaped pores with a narrow thickness distribution whose mean value is 14 Å. This interlayer spacing causes an increase in surface area of about 190 m 2/g by SAXS.

Location of specific oligosaccharides in heparin in terms of their distance from the protein linkage region in the native proteoglycan.

Studies were conducted to define the location of components and sequences in heparin with respect to their distance from the peptide linkage in the native proteoglycan. A purified heparin-oligopeptide was linked via its amino terminus to a matrix containing an azo bond and an activated carboxyl group. The polysaccharide chain was maximally degraded, either with heparinase or nitrous acid, and the soluble products were removed. The heparin-oligopeptide fragments that remained on the matrix were released by reductive cleavage of the azo linkage and characterized. The fragments, as well as heparin released without prior degradation, contained serine and glycine as the principal amino acids; the ratio of galactose to xylose was 2:1. The ratio of glucosamine to serine of 33:1 in the undegraded heparin was reduced to 6:1 and 1:1 in the heparinase-treated and nitrous acid-treated products, respectively. The undegraded sample and the fragments contained phosphate in equivalent amounts, demonstrating its presence in the heparin-protein linkage region. The heparin-oligopeptide preparation was also fractionated by gel filtration and high and low molecular weight fractions thus obtained were each linked to the insoluble matrix. The products that were subsequently released were subfractionated on a molecular weight-calibrated column of Sephadex G-200, and eluates were assayed for activity in promoting the neutralization of thrombin and factor Xa by antithrombin. The results revealed a sharp decrease in specific activity in heparin-oligopeptide fractions below Mr = 15,000 indicating that the anticoagulant-conferring segment is located at about 20 disaccharide units away from the peptide linkage region.

Effects of Ascorbic Acid on Display Life of Ground Beef

Fresh ground beef containing 20 and 25% fat was either treated with 0.01, 0.05 or 0.10% crystalline ascorbic acid or remained as non-treated controls. Samples were displayed in polyvinyl chloride (PVC) film for up to 10 d (24 h/d) at 2 to 3°C under 1076 lux G. E. Natural light. Measures of display life included visual color scores, reflectance measurements, sensory panel scores, thiobarbituric acid (TBA) values and microbial standard plate counts (SPC). At days 1, 3 and 5 of display, average and worst point visual color scores were judged brighter for all ascorbic acid treatments compared to controls. Lower metmyoglobin percentages, higher %R630nm/%R580nm and higher CIE a* readings at days 3, 5 and 10 for the ascorbic acid-treated product supported visual color results. Higher fat (25%) and higher ascorbic acid levels (0.05 and 0.10%) gave brighter visual color responses at 5 d of display than the 20% fat product and that containing 0.01% ascorbic acid. More intense sensory panel beef flavor was associated with the 0.05 and 0.10% ascorbic acid treatments. More off-flavor was found in the higher fat product (25%). TBA values were not different for fat level comparisons, but were lower for the 0.05 and 0.10% ascorbic acid treatments. At day 5 of display, SPC were not affected by ascorbic acid treatment. The 25% fat product had lower SPC at day 5.

Vitamin K 1 dependent carboxylase: β-Carboxylation of t-butyloxycarbonylaspartic acid α-benzyl ester

Rat liver microsomes solubilized by Triton X-100 catalyze the vitamin K 1 dependent incorporation of carbon-14 from [ 14C]NaHCO 3 into t-butyloxycarbonylaspartic acid α-benzyl ester. High voltage electrophoresis of the alkaline hydrolysate of the products of this reaction demonstrates the presence of a labelled species (A) whose electrophoretic mobility is identical to that of β-carboxyaspartic acid. High voltage electrophoresis of the acid-treated products reveals the disappearance of A and the appearance of a labelled species whose electrophoretic mobility is identical to that of aspartic acid. These experiments provide unequivocal evidence for the vitamin K 1 dependent β-carboxylation of an aspartic acid side chain, and they constitute the first report of such an enzymatic activity in microsomes.

ζ-POTENTIALS AND DYEING PROPERTIES OF FORMALIZED AND ACID-TREATED FORMALIZED POLY(VINYL ALCOHOL) FIBERS IN AQUEOUS SOLUTIONS OF DIRECT DYE

The ζ-potentials and dyeing properties of formalized poly(vinyl alcohol) (PVA) fiber (I) and its acid-treated product (II) in aqueous solutions of a direct dye, Benzopurpurine 4B, have been studied. The ζ-potentials of the fibers were measured by the streaming-potential method. The surface dye adsorption (Ms) of the fibers was calculated from the ζ-potentials obtained and the total dye adsorption (Mt) was determined by the colorimetric method.The negative ζ-potentials and Ms for I and II increased with an increase in the degree of formalization of the fibers. On the other hand, Mt, the surface area (Sa) covered by dye molecules, and the degree of swelling of these fibers decreased with increasing degree of formalization. The negative ζ-potentials and Ms for I were fairly larger than those for II. However, Mt, Sa, and the degree of swelling for the former were considerably smaller than those for the latter.It is apparent that the surface dyeing behavior of I and II with the direct dye is remarkably different from the total dyeing behavior of these fibers.