Impact of impregnation and bleaching on the surface hardness of oak (Quercus petraea L.) wood

The impact of impregnation and bleaching on the hardness of varnish layers on oak (Quercus petraea L.) wood was investigated. A number of solutions [sodium hydroxide (NaOH) and hydrogen peroxide (H₂O₂); NaOH, calcium hydroxide, and H₂O₂; NaOH, magnesium sulfate, and H₂O₂; sodium bisulfate and H₂C₂O₄ · 2H₂; sodium silicate and H₂O₂; and potassium permanganate, sodium bisulfate, and H₂O₂] were applied at a concentration of 18% to bleach both impregnated [Tanalith‐CBC (T‐CBC) or Imersol‐WR 2000 (I‐WR 2000)] and unimpregnated (natural) wood panels. Subsequently, a water‐based varnish (WB) was coated over the samples, and the hardness of the varnished layers was determined in accordance with ASTM D 4366. Among the samples that were varnish‐coated without bleaching, T‐CBC/WB yielded the highest hardness (59.50), whereas I‐WR 2000/WB exhibited the lowest (49.17). However, among the samples varnish‐coated after bleaching, the highest (56.50) and lowest (40.83) varnish hardness values were obtained with T‐CBC/solution 2/WB and I‐WR 2000/solution 4/WB, respectively. All the chemicals used for the bleaching process reduced the surface hardness. However, after the varnish coating, except for solutions 4 and 6, all the solutions showed hardness values similar to those of varnish‐coated natural (control) samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 498–504, 2004     

Effect of outdoor exposure and bleaching on surface color and chemical structure of scots pine

This study was carried out in order to investigate the changes on chemical structure and surface color of scots pine (Pinus sylvestris L.) after exterior conditioning followed by bleaching process. Specimens were first exposed to exterior conditions for 12 months, and then bleached with three different solutions: 18% NaOH + H₂O₂, NaSiO₃ + H₂O₂, and CaOH₂ + H₂O₂. Afterwards, specimens were re-exposed to exterior conditions for 12 months. Measurement of color differences and changes in chemical structures of finishing after the process of exposure to outdoors and bleaching were made according to the ASTM D-2244 standard. As a result, it was deduced that exposure to exterior conditions causes color differences in specimens while bleaching with given solution groups reduces that affect and reverts the surface color to that of natural control specimens. However, specimens exposed to 12 months exterior conditioning had more discoloration than that of natural control specimens. This finding leads to a conclusion that in restoration of uncoated or unfinished wood exposed to exterior conditions for 12 months, bleaching process could increase service and economic life of material.     

Impacts of impregnation with Timbercare Aqua on the red and yellow color tone of some woods and varnishes

This study has been performed for determining the effects of impregnation with Timbercare Aqua (Tc) on the red and yellow color tone of some woods and varnishes. For this purpose, the test samples prepared from Oriental beech, European oak, Scotch pine, Oriental spruce, and Uludag fir woods, which met the requirements of ASTM D 358, was impregnated with Tc according to ASTM D 1413 and producer's definition. After impregnation, wood surfaces have been coated by Sayerlack parquet varnish (Sp), Sayerlack interior varnish (Si), and Sayerlack exterior varnish (Se) varnishes in accordance with the ASTM D 3023 standards. According to ASTM D 2244, the red and yellow color tone of samples after varnishing process was determined. As a result, the value of red color tone was the highest in Oriental beech (15.21) and the lowest in Uludag fir (5.38). For the wood material, impregnation material, and varnish interaction, the red color tone value was the highest in Oriental beech + Tc + Sp (18.43) and the lowest in Uludag fir + Tc + Si (3.92). The value of the yellow color tone was the highest in pine (34.45) and the lowest in Oriental beech (26.50). For the wood material, impregnation material, and varnish interaction, the yellow color tone value was the highest in Oriental spruce + Tc + Sp (42.12) and the lowest in Oriental beech + Tc + Si (21.47). This effect may be due to the impacts of impregnation chemical on wood extractives and color pigments in varnish. Accordingly, it should be taken into care for applications where the red and yellow color tone value is important. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Phosphorus transformation in a soybean-cropping system in Andosol: effects of winter cover cropping and compost application

Understanding phosphorus (P) transformation is necessary to develop sustainable P management practices on Andosol with large P-fixing capacity. This study was conducted during 2005–2007 in northeastern Japan to determine how the amounts of inorganic P (P_i) and organic P (P_o) fractions change in a Silandic Andosol under soybean production [Glycine max (L.)]. Two treatments were examined: application of composted cattle manure (0 (P0), 61 (P1), and 122 or 183 (P2) kg P ha⁻¹ year⁻¹) and winter cover cropping (no cover crop, rapeseed [Brassica napus], and cereal rye [Secale cereale L.]). Compost was applied before soybean seeding; cover crops were seeded after soybean harvest without further fertilization. Soil P was extracted sequentially with anion exchange resin (P_i), 0.5M NaHCO₃ (P_i, P_o), 0.1M NaOH (P_i, P_o), and 0.5M H₂SO₄ (P_i). Soybean removed 42.3 and 48.5 kg P ha⁻¹ (only 23 and 10% of the added P), respectively, in P1 and P2. In the P2 soil, 64% of excess P was distributed into P_i fractions, mainly resin-P_i and NaOH–P_i (29 and 19%, respectively). In P0, despite no P addition, soybean removed 41.5 kg P ha⁻¹ concurrently with a decrease in NaOH–P_i, suggesting its potential contribution to soybean P uptake. Neither of cover crops had significant effect on soil P fractions during the 3 year period.     

Impact of impregnation with boron compounds on the surface hardness and abrasion resistance of some varnished woods

This study was performed to determine the impact of impregnation with boron compounds on the surface hardness and abrasion resistance of some varnished woods. For this purpose, test specimens prepared from Oriental beech, White oak, Scotch pine, and Uludag fir, which met the requirements of ASTM D 358, were impregnated according to ASTM D 1413‐99 with boric acid (Ba), borax (Bx), and boric acid + borax (Ba+Bx) by the vacuum technique. After impregnation, the surfaces are coated with synthetic (Sn), water‐borne (Wb) and acid hardening (Ah) varnishes in accordance with ASTM D 3023. the surface hardness of specimens after the varnishing process was determined in accordance with ASTM D 4366. The abrasion resistance of specimens after the varnishing process was determined in accordance with TS 4755. According to the wood type, impregnation material and varnish type, the surface hardness was the highest for Oriental beech impregnated with borax + boric acid and acid hardening varnish and the lowest for Uludag fir impregnated with borax + boric acid and synthetic varnish. According to the wood type, impregnation material and varnish type, the abrasion resistance was the highest for Oriental beech impregnated with borax + boric acid and acid hardening varnish and the lowest for Scotch pine impregnated with borax + boric acid and synthetic varnish. Those results should be taken into account for applications like parquet, flooring etc., where the surface hardness and abrasion resistance values are very important. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ozonide ions on the surface of MgO nanocrystals

The adsorption properties of oxygen radicals on the surface of polycrystalline oxides can provide relevant information about the functionality of specific surface sites in oxidation catalysis. Using electron paramagnetic resonance spectroscopy, we investigated O₂ adsorption at MgO nanocrystal surfaces which were previously enriched with O⁻ radicals i.e. trapped hole centers. On dehydroxylated particle surfaces, two ozonide radical types O ₃ ⁻ were isolated as adsorbates and the related energies for O₂ adsorption were found to be 55 ± 5 kJ mol⁻¹ and 100 ± 5 kJ mol⁻¹. The respective adsorption sites are assigned to hole centers trapped on oxygen terminated corners and cation vancancies, respectively. In addition, O ₃ ⁻ ions were also employed as probes for electron trapping sites on partially hydroxylated sample surfaces. Five types of O⁻ radicals emerge from surface colour centre bleaching with N₂O, but only two of them adsorb O₂ at room temperature. A connection between the well-characterized (H⁺)(e^-) defect – an electron trapped in close vicinity of a nearby proton [Chiesa et al. J. Phys. Chem. B 109 (2005) 7314] – and one ozonide type which exhibits significant magnetic coupling with an adjacent proton, was established on the basis of their production parameter dependence. Although the g tensor of an O₃ ⁻ species reflects the properties of the radical itself rather than the structure of the adsorption site, the related signatures are proposed to serve also as spectroscopic fingerprints for catalytically relevant surface anion environments.     

Soy protein combined with copper and boron compounds for providing effective wood preservation

Chromated copper arsenate (CCA), an arsenicbased wood preservative, is toxic to human health and the environment. Although CCA is stable in seasoned wood, there are potential dangers during CCA manufacture, lumber treatment, and waste disposal. This research was conducted to study the effectiveness of soy products to replace toxic chromium and arsenic compounds in wood preservative formulations. Three soy product (Arpro 2100, HM 90, and Supro 760) were used as fixative agents in preservative solutions containing anhydrous CuSO₄ and Na₂B₄O₇·10H₂O. The decay resistance of treated wood blocks was measured by a soil-block culture method. Despite the large molecular sizes of copper-protein and copper-boron-protein complexes, southern pine sapwood was treatable with these preservative formulations. Wood samples treated with >6 kg°m⁻³ CuSO₄ and 7.5 kg·m⁻³ soy product, and subsequently leached for 3 d and exposed to the decay fungus Gloeophyllum trabeum (Fr.) Mur., sustained only 0.5% weight loss over 12 wk. Wood samples needed 40 kg·m⁻³ CuSO₄ and 50 kg·m⁻³ soy protein to resist the copper-tolerant decay fungus Postia placenta (Fr.) M. Lars. & Lomb. These results suggest that soy-based wood preservatives can prevent wood products from fungal attack and can replace CCA.     

Electrochemical behavior of an inorganic–organic hybrid based on isopolymolybdate anions and ethylenediamine

The one-dimensional inorganic–organic compound, (C₂H₁₀N₂)[Mo₃O₁₀], was synthesized hydrothermally, and characterized by single crystal X-ray diffraction. The compound was used as a bulk-modifier to fabricate a renewable three-dimensional chemically modified carbon paste electrode (Mo-CPE) by direct mixing. The electrochemical properties of (C₂H₁₀N₂)[Mo₃O₁₀]-modified Mo-CPE were investigated with respect to their pH-dependence, stability and electrocatalytic activity. The hybrid material bulk modified Mo-CPE not only displays good electrocatalytic activity toward the reduction of BrO₃ ⁻, IO₃ ⁻, NO₂ ⁻ and H₂O₂, but also exhibits good stability and multiple repeatability by simply polishing on the surface of a wet filter paper, a feature which is important for practical applications.     

Impact of impregnation with boron compounds on the surface hardness of varnished wood

This study was performed to determine the impact of impregnation with boron compounds on the surface hardness of varnished wood materials. For this purpose, test specimens prepared from Oriental beech (Fagus orientalis Lipsky) and oak (Quercus petreae Lipsky), which met the requirements of ASTM D 358, were impregnated according to ASTM D 1413 with boric acid and borax by a vacuum technique. After impregnation, the surfaces were coated by cellulosic, synthetic, polyurethane, waterborne, acrylic, and acid hardening varnishes in accordance with ASTM D 3023. The surface hardness of the specimens after the varnishing process was determined in accordance with ASTM D 4366. According to the wood type, impregnation material, and varnish type, the surface hardness was highest for the oak impregnated with borax and acrylic varnish and lowest for the oak impregnated with borax and synthetic varnish. Therefore, impregnation with boron compounds showed an increasing impact on the surface hardness of the varnished wood. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis of borosilicalite-1 with more than four boron per unit cell from fluoride containing media

More than four boron per unit cell has been introduced into the framework of silicalite-1, using fluorine containing media. The initial gels were of composition 9MF–xH₃BO₃–10SiO₂–1.25TPABr–330 H₂O with M = NH₄, Na, K and Cs and x = 0.1–10. The syntheses were carried out in hydrothermal conditions at 170°C. The amount of incorporated TPA⁺ ions remains quasi constant (3.5–3.8/u.c.) up to 4 B/u.c., while it decreases with increasing boron content. The amount of tetrahedral B/u.c. can be as high as 8 in presence of K⁺ or Cs⁺ ions in the as-synthesized samples. It is observed that the preferential countercations to framework negative charges related to the presence of tetrahedral boron, [SiOB]⁻, are TPA⁺, K⁺ and Cs⁺ ions. It is interpreted, that the −4.0 ppm versus BF₃.OEt₂ NMR line stems from tetrahedral framework boron, while the −2.9 ppm NMR line represents both extraframework and/or tetracoordinated deformed framework boron in the structure.     

Impacts of impregnation with boron compounds on surface roughness of woods and varnished surfaces

This study determines the effects of the process of impregnation of boron compounds on the surface roughness of Oriental beech, Scotch pine, Oriental spruce, and Uluda? fir woods and varnished surfaces. For this purpose, samples are prepared according to ASTM D 358 and impregnated according to ASTM D 1413‐99 with a 5.5% solution of boric acid (Ba), borax (Bx), and Ba with Bx (Ba + Bx) and varnished with synthetic varnish (Sv) and water‐based varnish (Wb) in accordance with ASTM D 3023. The surface roughness is determined according to ISO 4287 and TS 930 standards. The results indicate that the surface roughness is the highest in Uluda? fir, Wb, and Bx and the lowest in Oriental spruce, Sv, and Ba + Bx. For the combination of wood, impregnation material, and varnish, the surface roughness is the highest in Oriental beech with Bx and Wb and the lowest in Scotch pine with Ba + Bx and Sv. The surface roughness is less in impregnated samples than unimpregnated samples and in impregnated and varnished samples than impregnated and unvarnished samples. According to these results, boron compounds decrease the surface roughness of varnishes and wood materials. Thus, impregnation of wood with boron compounds decreases the surface roughness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4952–4957, 2006     

Exploration of molten hydroxide electrochemistry for thermal battery applications

The electrochemistry of molten LiOH–NaOH, LiOH–KOH, and NaOH–KOH was investigated using platinum, palladium, nickel, silver, aluminum and other electrodes. The fast kinetics of the Ag⁺/Ag electrode reaction suggests its use as a reference electrode in molten hydroxides. The key equilibrium reaction in each of these melts is 2 OH^– = H₂O + O^2– where H₂O is the Lux-Flood acid (oxide ion acceptor) and O^2– is the Lux–Flood base. This reaction dictates the minimum H₂O content attainable in the melt. Extensive heating at 500 °C simply converts more of the alkali metal hydroxide into the corresponding oxide, that is, Li₂O, Na₂O or K₂O. Thermodynamic calculations suggest that Li₂O acts as a Lux–Flood acid in molten NaOH–KOH via the dissolution reaction Li₂O_(s) + 2 OH^– = 2 LiO^– + H₂O whereas Na₂O acts as a Lux–Flood base, Na₂O_(s) = 2 Na⁺ + O^2–. The dominant limiting anodic reaction on platinum in all three melts is the oxidation of OH^– to yield oxygen, that is 2 OH^– 1/2 O₂ + H₂O + 2 e^–. The limiting cathodic reaction in these melts is the reduction of water in acidic melts ([H₂O] [O^2–]) and the reduction of Na⁺ or K⁺ in basic melts. The direct reduction of OH^– to hydrogen and O^2– is thermodynamically impossible in molten hydroxides. The electrostability window for thermal battery applications in molten hydroxides at 250–300 °C is 1.5 V in acidic melts and 2.5 V in basic melts. The use of aluminum substrates could possibly extend this window to 3 V or higher. Preliminary tests of the Li–Fe (LAN) anode in molten LiOH–KOH and NaOH–KOH show that this anode is not stable in these melts at acidic conditions. The presence of superoxide ions in these acidic melts likely contributes to this instability of lithium anodes. Thermal battery development using molten hydroxides will likely require less active anode materials such as Li–Al alloys or the use of more basic melts. It is well established that sodium metal is both soluble and stable in basic NaOH–KOH melts and has been used as a reference electrode for this system.     

Kinetics of hydrogen peroxide oxidation of alkyl dimethyl amines

We measured the absolute rate constants for the hydrogen peroxide oxidation of two different octyl dimethyl amines in isopropanol/water mixtures at 23°C. The amines were 1-octyl dimethyl amine (1) and 2-ethylhexyl dimethyl amine (2); their structures were analogous to those most often encountered in commercial alkyl dimethyl amine oxide production. The observed first-order rate constants for the disappearance of amine across a range of H₂O₂ concentrations (0.5–8 M) indicated that the overall rate was first-order in amine and 3/2-order in H₂O₂. Calculations showed k ₁=0.16 M⁻¹h⁻¹, k ₂=0.046 M⁻¹h⁻¹, and k ₁/k ₂=3.5. The rates appeared to decrease with increasing steric hindrance around the nitrogen atom. We also investigated the effect of water on the reaction rates. When [H₂O]<∼4.5 M in isopropanol, the rates increased with increasing [H₂O]; for [H₂O]>∼4.5 M, the rates were insensitive to [H₂O].     

Surface properties of tannin-impregnated and varnished beech wood after exposure to accelerated weathering

The aim of this study was to determine selected surface properties of varnished beech wood impregnated with natural extracts after exposure to accelerated weathering. Beech wood samples were impregnated with aqueous solutions of 5 and 10% mimosa (Acacia mollissima) and quebracho (Shinopsis lorentzii) tannins. After weathering, colour changes (ΔL*, Δa*, Δb*, and ΔE*) in addition to scratch resistance and surface hardness values were calculated and evaluated. As a result of the weathering process, greater colour changes (ΔE*) were detected in the beech wood samples impregnated with tannins compared with the unimpregnated control samples. The least colour change occurred in the Tanalith-E-impregnated samples. Total colour change was adversely affected with tannin impregnation after the weathering processes. In terms of surface hardness and scratch resistance, the highest values were observed in the mimosa-solution-impregnated and control samples. Furthermore, it was found that scratch resistance and hardness values tended to increase during the first period of weathering and decreased thereafter. Regarding surface properties, the best results were obtained when polyurethane varnish was employed compared with the other varnish types.     

Bleaching of alkali-refined vegetable oils with clay minerals

Bleaching efficiencies of bentonites, montmorillonites and sepiolites for alkali-refined rapesseed, soybean, wheatgerm, safflower, corn, cottonseed and sunflower oils were investigated by a batch method at 110°C. The sepiolites with more acid sites at −5.6 < H_o ≥ −3.0 were the most effective in bleaching of each alkali-refined oil. Surface area and acidity at −5.6>H_o ≥ −3.0 were highly significant with bleaching efficiency. The sepiolites (numbers 2 and 3) were more suitable than standard activated clay because they were more effective both in retaining tocopherols and in reducing free fatty acids after bleaching.     

Influence of MeF2 (Me = Mg, Ca, Sr, and Ba) on the electrical properties of glasses in the MeF2-Na2B4O7 system

Glasses in the MeF₂-Na₂B₄O₇ (Me = Mg, Ca, Sr, and Ba) system have been synthesized. It is shown that the glass formation is observed at a MeF₂ content of up to 40 mol %. The influence of the MeF₂ content on the electrical conductivity and the fluorine concentration in the glass bulk is examined. From the analysis of the concentration dependence of the electrical conductivity with due regard for the fluorine content, it is concluded that the glass structure is predominantly built up of the polar groupings Na⁺[BO_4/2]^-, Na⁺[F-BO_3/2], Me _1/2 ²⁺ [BO_4/2]⁻, Me _1/2 ²⁺ [F⁻BO_3/2], [MeF_4/2], and [MeF_6/3] and the BO_3/2 nonpolar structural-chemical units. The electricity transport is governed by the migration of sodium ions formed upon dissociation of the Na+[BO_4/2]^-and Na+[F^-BO_3/2] groupings. An increase in the MeF₂ content leads to a decrease in the total concentration of sodium ions, a decrease in the Na⁺[BO_4/2]^- concentration, and an increase in the Na⁺[F^-BO_3/2] concentration. Upon introduction of MeF₂ up to ∼20 mol %, the fluorine losses during the synthesis are caused by the dehydration of glass melt. An addition of 20–25 mol % MeF₂ brings about the saturation of the glass by the [F^-BO_3/2]-type structural units, so that the fluorine concentration reaches a saturation in the structures of calcium-, strontium-, and barium-containing glasses and increases in magnesium-containing glasses, owing to the formation of the [MgF+_6/3] groupings.     

Synthesis of deuterium labeled cholesterol and steroids and their use for metabolic studies

A simple method is described for the preparation of [6,7,7⁻²H₃] sterols and steroids. The synthesis starts with a Δ⁵-sterol or steroid and involves preparation of the 6-oxo-3α,5α-cyclosteroid, base exchange in the presence of deuterium oxide to introduce two deuteriums at the C-7 position and sodium borodeuteride reduction of the 6-oxo group to introduce the third deuterium atom at C-6. Rearrangement of the [6,7,7⁻²H₃]6α-hydroxy-3α,5α-cyclosteroid then gives the desired [6,7,7^-2H₃]-Δ⁵ sterol or steroid. [6,7,7⁻²H₃]Cholesterol, [6,7,7⁻²H₃]pregnenolone and [6,7,7⁻²H₃]3β-hydroxyandrost-5-en-17-one were synthesized in this fashion and [6,7,7⁻²H₃]progesterone was prepared from the [6,7,7⁻²H₃]pregnenolone. Three examples of the use of these deuchromatography-mass spectrometry. The chrysophyte alga,Ochromonas malhamensis, was shown to be capable of introducing an extra methyl or ethyl group at C-24 of the side chain of [6,7,7⁻²H₃]cholesterol to yield brassicasterol and poriferasterol, respectively. The ovary of the echinoderm,Asterias rubens, was demonstrated to metabolize [6,7,7⁻²H₃]progesterone to yield mainly the 5α-isomers of pregnane-3,20-dione and 3β-hydroxypregnan-20-one. However, the 5β-isomers of these compounds were also detected as minor products for the first time as progesterone metabolites in this animal. Isolated oocytes of the frog,Xenopus laevis, produced a number of metabolites of [6,7,7⁻²H₃]progesterone. In this report, two of them were shown to be 17α-hydroxy-pregn-4-en-3,20-dione and 20α-hydroxypregn-4-en-3-one. Presented at the “Sterol Symposium” of the American Oil Chemists' Annual International Conference, New Orleans, LA, May 1981.     

Influence of MeF2 (Me = Mg, Ca, Sr, and Ba) on the electrical properties of glasses in the MeF2-Na2B4O7 system

Glasses in the MeF₂-Na₂B₄O₇ (Me = Mg, Ca, Sr, and Ba) system have been synthesized. It is shown that the glass formation is observed at a MeF₂ content of up to 40 mol %. The influence of the MeF₂ content on the electrical conductivity and the fluorine concentration in the glass bulk is examined. From the analysis of the concentration dependence of the electrical conductivity with due regard for the fluorine content, it is concluded that the glass structure is predominantly built up of the polar groupings Na⁺[BO_4/2]^-, Na⁺[F-BO_3/2], Me _1/2 ²⁺ [BO_4/2]⁻, Me _1/2 ²⁺ [F⁻BO_3/2], [MeF_4/2], and [MeF_6/3] and the BO_3/2 nonpolar structural-chemical units. The electricity transport is governed by the migration of sodium ions formed upon dissociation of the Na+[BO_4/2]^-and Na+[F^-BO_3/2] groupings. An increase in the MeF₂ content leads to a decrease in the total concentration of sodium ions, a decrease in the Na⁺[BO_4/2]^- concentration, and an increase in the Na⁺[F^-BO_3/2] concentration. Upon introduction of MeF₂ up to ∼20 mol %, the fluorine losses during the synthesis are caused by the dehydration of glass melt. An addition of 20–25 mol % MeF₂ brings about the saturation of the glass by the [F^-BO_3/2]-type structural units, so that the fluorine concentration reaches a saturation in the structures of calcium-, strontium-, and barium-containing glasses and increases in magnesium-containing glasses, owing to the formation of the [MgF+_6/3] groupings.     

Direct synthesis of dimethyl carbonate from methanol and carbon dioxide over H3PW12O40/CeXZr1?XO2 catalysts: Effect of acidity of the catalysts

Ce _X Zr_1−X O₂ catalysts were prepared by a sol-gel method, and H₃PW₁₂O₄₀/Ce _X Zr_1−X O₂ catalysts were then prepared by an impregnation method. Both catalysts were applied to the direct synthesis of dimethyl carbonate from methanol and carbon dioxide in a batch reactor. NH₃-TPD experiments were carried out to investigate the effect of acidity on the catalytic performance of Ce _X Zr_1−X O₂ and H₃PW₁₂O₄₀/Ce _X Zr_1−X O₂. Catalytic performance of Ce _X Zr_1−X O₂ and H₃PW₁₂O₄₀/Ce _X Zr_1−X O₂ was closely related to the acidity of the catalysts. The amount of dimethyl carbonate produced over both Ce _X Zr_1−X O₂ and H₃PW₁₂O₄₀/Ce _X Zr_1−X O₂ catalysts increased with increasing acidity of the catalysts. This indicates that acidity of the catalyst played a key role in determining the catalytic performance of Ce _X Zr_1−X O₂ and H₃PW₁₂O₄₀/Ce _X Zr_1−X O₂ in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Catalytic activity of H₃ PW₁₂O₄₀/Ce _X Zr_1−X O₂ was higher than that of the corresponding Ce _X Zr_1−X O₂. The enhanced catalytic performance of H₃ PW₁₂O₄₀/Ce _X Zr_1−X O₂ was attributed to the Br?nsted acid sites provided by H₃PW₁₂O₄₀.     

Biochemical,functional, and histochemical effects of essential fatty acid deficiency in rat kidney

The present study was designed to examine the effects of EFA deficiency (EFAD) on biochemical, functional, and structural aspects of the kidney in growing and adult rats fed a normal or EFAD diet for 9 wk after weaning. Food and fluid intake (FI), urine volume, and Na⁺ and K⁺ excretions were measured weekly from weeks 4 to 8 by placing the rats in individual metabolic cages for 24 h. At week 9, Li⁺ and a 5% water load, respectively, were administered at 14 and 1.5 h prior to glomerular and proximal tubular function studies, as assessed by 3-h creatinine (C_Cr) and Li⁺ (C_Li+) clearances. Hematocrit and urine volume; serum and urine [Cr], [Li⁺], [Na⁺], and [K⁺]; and renal FA distribution were also measured. Data [corrected to 100 g/body weight (bw) and presented as means ±SEM] were significant, at P<-0.05. Despite a similar ingestion of solids from weeks 4 to 7 (weeks 7 to 10 of life), the rats on the EFAD diet showed a decreased body weight from week 5. From weeks 4 to 8, Fl and urine volume were similar for both groups, but the Fl increased at week 6 in the EFAD group; 24-h Na⁺ and K⁺ excretions were similar at all weeks, except for an increase in the EFAD group for both ions at week 7. In the EFAD group, C_Cr and C_Li+ decreased by 27 and 56.3%, respectively (385.7±33.4 vs. 280±21.1, and 21.0±2.1 vs. 9.2±1.1 μL/min/100 g; n=9 vs. 10), the latter result suggesting increased proximal reabsorption. The 3-h Na⁺ and K⁺ excretions were similar, but the Li⁺ decreased (0.78±0.06×10⁻² vs. 0.32±0.03×10⁻² μeq/min/100 g) in the EFAD group, giving additional support to the suggestion. Renal structure was normal and similar for both groups, but the EFAD group showed a more prominent proximal tubule brush border, together with heavier periodic acid-Schiff staining in all specimens from weeks 5 to 9. In the EFAD group, FA of the n−9 and n−7 series were higher, but most of the n−6 series were lower as a percentage of total lipids in the medulla and cortex. Medullary levels of 20∶4n−6 were maintained, 22∶4n−6 declined twice, arachidonic acid was maintained, and 20∶5n−3 was lower. The EFAD diet affected glomerular function, proximal tubular structure and function, and FA distribution in the rat kidney.