Solution Properties of Alkyl β-D-Maltosides

Alkyl β-D-maltosides are an important class of sugar-based nonionic surfactants and have been widely studied. Nevertheless, it is still necessary to investigate further their amphiphilic structure-surface property relationships. In this article, we reported a series of properties of synthetic alkyl β-D-maltosides ( 6a – 6i , n = 6–18) including their hydrophilic–lipophilic balance (HLB) number, water solubility, hygroscopicity, moisture-retention capacity, foaming ability, surface tension, thermotropic phase behavior, and skin irritation. Their HLB number and water solubility decreased with increasing alkyl chain length. Hexyl β-D-maltoside exhibited the strongest hygroscopicity and moisture-retention capacity. Decyl β-D-maltoside and dodecyl β-D-maltoside possessed excellent foaming power and foaming stability. Furthermore, the critical micelle concentration (CMC) of alkyl β-D-maltoside ( 6a – 6g , n = 6–14) and their surface tension at CMC decreased with increasing alkyl chain length. At last, alkyl β-D-maltosides ( 6a – 6g ) should be considered as safe surfactants by the skin irritation assessment.     

To What Extent Can Hyperelastic Models Make Sense the Effect of Clay Surface Treatment on the Mechanical Properties of Elastomeric Nanocomposites?

The poor knowledge about nonlinear mechanical behavior of elastomer nanocomposites arises from the incomplete information on the interface. Application of hyperelastic models provides more insights into the nature and the situation of interaction between the elastomeric matrix and nanofillers. The current work seeks to address the effect of interphase strength on tensile properties of the elastomer nanocomposites under large deformations. Acrylonitrile butadiene rubber (NBR)/clay nanocomposite is selected for modeling on account of complexities associated with exfoliation/intercalation of clay platelets. In particular, it is aimed to specify to what extent hyperelastic models can capture the effect of clay surface functionalization on the mechanical behavior of nanocomposites. Attachment of silane functional groups to the clay surface is confirmed by Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and thermogravimetric analyses. Different hyperelastic models are examined to detect the characteristic of NBR/clay nanocomposites. The powerfulness/weakness of the used models are featured by calculating the strain energy functions and material parameters, meanwhile, by comparing model outputs with experimental data of tensile tests.

     

Effect of the Mesostructuration of the Beta Zeolite Support on the Properties of Cobalt Catalysts for Fischer–Tropsch Synthesis

The effect of mesostructuration of beta zeolite and of metal loading on the properties of cobalt-based catalysts for Fischer–Tropsch synthesis was studied in this work. The most active catalyst was the mesostructured beta zeolite-supported cobalt (10%), which also showed a low selectivity to methane and the lowest olefin/paraffin ratio.     

Effect of Microsilica Addition on the Properties of Mullite-Corundum Ceramic

1IntroductionCorundum-mullite materials have been recognizedand adopted as important refractories because of theirexcellent properties,such as high refractoriness,highresistance to creep,good mechanical and chemical sta-bility at high temperatures,high th…     

Effect of Sintering Additive on the Properties of Sialon-SiC by Gelcasting

Sintering additivesto gelcasting Sialon‘SiC were decided by the optimizing experiments , The resuhs show that Sialon-SiC can be sintered under 1450℃ and sintering temperature dcreases by 100℃，when 2%～3% TiO2 or Guangxi clay is used as sintering additive.     

The Effect of Cobalt on the Degradation of Methyl β-D-Gluco-Pyranoside by Oxygen in Aqueous Sodium Hydroxide Solution

Abstract

The effect of Co(II) (0 to 0.25 mW CoSO₄) on the degradation of methyl β-D-glucopyranoside (MBG) at 120°C in 1.25M NaOH with 0.68 MPa oxygen pressure was studied. When the Co(II) was increased from 0.00 to 0.01 to 0.05 mM the MBG half-life decreased from 12 to 6 to 1.5 hours, reflecting approximately a 0.5 order kinetic dependence on cobalt. An oxidation-reduction cycle between Co(II) and Co(III) involving oxidation of Co(II) by oxygen and oxidation of the glucoside by Co(III), hydroxyl radical, or superoxide is proposed for the degradation. At the 0.25 mM Co(II) addition level highly adsorptive Co(OH)₂ formed prior to reaction initiation with oxygen and removed otherwise soluble cobalt from solution. This resulted in lower rates of MBG degradation than obtained even at 0.01 mM Co(II) addition. However, Co(II) solubility could be enhanced if silicate anions or polyols (including MBG) were added to the alklaine medium prior to the Co(II) addition. In reactions initially containing 0.25 mM soluble Co(II), an adsorptive precipitate, presumably CoO(OH), gradually formed after reaction initiation with oxygen. Precipitation of the Co(III) solid coincided with a rapid decline in the rate of MBG degradation. Cobalt had little effect on the products of MBG degradation.     

Effect of Additive ZrO2 on Sintering Properties of MgO-CaO Bricks

The effect of electric fused ZrO2,m-ZrO2 and zirconite on the sintering properties of MgO-CaO bricks was studied and the effect of the ZrO2 content and temperature on BD (bulk density), AP(apparent porosity)and CCS (Cold Crushing strength) of MgO-CaO bricks was investigated.The microstructure of burned specimens was analyzed by SEM. The result shows that the sintering property is best while 5% m-ZrO2 was added at 1 600 ℃.     

Synthesis and Aqueous Solution Properties of α-Dimethyl Oxamino Dodecyl Acid

Starting from α-chloro-lauric acid which was obtained from lauric acid through selectively chlorinating at the α-position with chlorine, a novel surfactant α-dimethyl oxamino dodecyl acid was synthesized with high yield via an economic route. The structure of α-dimethyl oxamino dodecyl acid was confirmed by means of Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry and ¹H nuclear magnetic resonance spectroscopy. Surface tension, foaming properties and emulsifying measurements were performed to study the aqueous solution properties of the synthesized surfactant. The results showed that the behavior of the α-dimethyl oxamino dodecyl acid strongly depend on the pH of aqueous solution: it had high surface activity, excellent foaming properties and emulsion stability for paraffin oil at acid pH while the corresponding properties decrease substantially at alkaline pH.     

Chemical Properties of 2‐Bromodecanoic Acid

Abstract

Some chemical equilibrium constants for 2‐bromodecanoic acid were investigated. The dimerization constant of 2‐bromodecanoic acid, k₂ =278 M^?1, in tert‐butylbenzene was first derived from IR spectroscopy measurements. Secondly, the distribution coefficient, k _d =799, was found by combining the value of k₂ with distribution data obtained from solvent extraction experiments evaluated with the aid of neutron activation analysis. Finally the dissociation constant, k _a =3.18 ?10^?3 M, was estimated from two‐phase titrations. A theoretical calculation was made based on the obtained constants and this calculation was validated by a second solvent extraction experiment that gave a good correspondence between calculated and experimental values.     

Effect of Ultrasound Frequency on the Precipitation Process of Supersaturated Sodium Aluminate Solution

The effects of frequency of ultrasound on the precipitation process of prepared supersaturated sodium aluminate solutions of practical concentration were studied experimentally under seeded, isothermal, batch crystallization conditions at various temperatures and initial ak(mole ratio of Na2O/Al2O3). The decomposition and the particle number percentage for size below 2 mm at time of 15 h were compared, particle size distribution and SEM photos of the product aluminum hydroxide were also analyzed. The results indicate that the ultrasonic treatment at 16 kHz can enhance the decomposition rate of sodium aluminate solutions, and also has effects on particle morphology and particle size distribution of aluminum hydroxide precipitated.     

Synthesis,Surface Properties,and Inhibiting Action of Novel Nonionic Surfactants on Carbon Steel Corrosion in 1 M Hydrochloric Acid Solution

In the present study novel nonionic surfactants were synthesized, characterized, and tested as corrosion inhibitors for carbon steel in 1 M HCl solution. The inhibiting performances of these surfactants were studied by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The adsorption of these inhibitors was well described by Langmuir adsorption isotherm, and the kinetic parameters were calculated and discussed. The inhibition efficiency (IE) was found to rise with increasing the concentration of these inhibitors. Polarization measurements revealed that the inhibitors acted as mixed-type inhibitors. The efficiencies obtained from the impedance measurements were in good agreement with those obtained from the weight loss and potentiodynamic polarization techniques which prove the validity of these tools in the measurements of the tested inhibitors. The surface parameters of the synthesized nonionic surfactants were investigated and the results showed that these surfactants have lower values of surface tension and are effective as wetting and emulsifying agents.     

Effect of Acid–Base Properties on the Catalytic Activity of Pt/Al2O3 Based Catalysts for Diesel NO Oxidation

The activity of Pt catalysts supported on Al₂O₃ modified with various acid–base additives has been investigated for oxidation of NO to NO₂. Although Pt dispersion was changed by the additives, there was no clear effect of Pt dispersion on the catalytic activity. The measurement of solid acid–base properties of the modified Pt/Al₂O₃ indicated that the NO oxidation activity increased by the increase of surface density of strong acid sites and decreased by the increase of basic sites. It was suggested that platinum on the acidic supports keeps its highly active metallic state for NO oxidation, while the formation of nitrate/nitrite on the basic supports inhibits the reaction on the Pt surface.     

Effect of Surface Treatment on Flow Boiling Heat Transfer Coefficient in CaSO4 Containing Water

This paper reports the influence of heat transfer surface treatment on the formation of calcium sulphate deposit during flow boiling heat transfer. The surface of several test heaters was treated by surface modification techniques, such as dynamic mixing magnetron sputtering [DLC （diamond-like carbon）, DLC-F （diamond-like carbon-fluorine） and AC （amorphous carbon）] and polishing to reduce surface energy. The results showed that heat transfer surface with low surface energy experienced significant reduction of formation of CaSO4 deposit. （1） Magnetron sputtering stainless steel heat transfer surface with DLC, DLC-F and plasma arc sputtering with AC did not change the surface roughness, but they reduced surface energy and improved heat transfer coefficient, so hindered CaSO4 deposit formation significantly. The DLC-F surface performed better than the DLC surface. （2） Surface energy played an important pole in improving heat transfer coefficient. The less the surface energy the more significant the heat transfer coefficient improved with other experimental conditions identical. （3） The polished surface improved the roughness of the heater, but owing to the high surface energy it was not better than the DLC-F surface for a long-term consideration on improving the heat transfer coefficient.     

Acid attack on hydrated cement — Effect of mineral acids on the degradation process

During acid attack on concrete structural components, a degraded layer develops whose properties as a protective barrier are decisive for durability. ²⁹Si NMR spectroscopy and ²⁷Al NMR spectroscopy were used with XRD to investigate the degraded layer on hardened cement paste exposed to HCl and H₂SO₄. The layer comprises an amorphous silica gel with framework silicates, geminate and single silanol groups in which Si is substituted by Al. Amorphous Al(OH)₃ and Fe(OH)₃ are present. The gel forms by polycondensation and cross-linking of C-A-S-H chains at AlO₄ bridging tetrahedra. In the transition zone between the degraded layer and the undamaged material, portlandite dissolves and Ca is removed from the C-A-S-H phases maintaining their polymer structure at first. With HCl, monosulphate in the transition zone is converted into Friedel's salt and ettringite. With H₂SO₄, gypsum precipitates near the degradation front reducing the thickness of the transition zone and the rate of degradation.     

The Effect of Zn-Al-Hydrotalcites Composited with Calcium Stearate and β-Diketone on the Thermal Stability of PVC

A clean-route synthesis of Zn-Al-hydrotalcites (Zn-Al-LDHs) using zinc oxide and sodium aluminate solution has been developed. The as-obtained materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The effects of metal ions at different molar ratios on the performance of hydrotalcites were discussed. The results showed that the Zn-Al-hydrotalcites can be successfully synthesized at three different Zn/Al ratios of 3:1, 2:1 and 1:1. Thermal aging tests of polyvinyl chloride (PVC) mixed with Zn-Al-LDHs, calcium stearate (CaSt(2)) and β-diketone were carried out in a thermal aging test box by observing the color change. The results showed that Zn-Al-LDHs can not only enhance the stability of PVC significantly due to the improved capacity of HCl-adsorption but also increase the initial stability and ensure good-initial coloring due to the presence of the Zn element. The effects of various amounts of Zn-Al-LDHs, CaSt(2) and β-diketone on the thermal stability of PVC were discussed. The optimum composition was determined to be 0.1 g Zn-Al-LDHs, 0.15 g CaSt(2) and 0.25 g β-diketone in 5 g PVC.     

Effect of Fluorine Ion on the Electrical Properties of Glasses in the Na2O–P2O5 System

The temperature–concentration dependence of the electrical conductivity of glasses in the NaPO₃–NaF system has been investigated. The regularities revealed are interpreted from the standpoint of the structural microinhomogeneity of glasses, which is due to the formation of polar structural units of the Na⁺[O^–POO_2/2], Na₂ ⁺[O^– ₂POO_1/2], Na⁺[F^–POO_2/2], and Na⁺F^– types. It is shown that the concentration dependence of the electrical conductivity is governed by the ratio between the concentrations of these structural units.     

Evolution of Acid–Base Properties of the Surface of Zinc Oxide Powders Obtained by the Method of Grinding in an Attritor

The evolution of the acid–base properties of the surface of zinc oxide powders during mechanical grinding in an attritor is studied. The study is performed using the methods of the adsorption of acid–base indicators and X-ray photoelectron spectroscopy. Correlations between the results obtained by these methods are established. It is shown that a monotonic decrease in the particle size of ZnO powders is accompanied by a nonmonotonic change in the surface acid–base properties.     

Assessing the Effect of Loop Mutations in the Folding Space of β2-Microglobulin with Molecular Dynamics Simulations

We use molecular dynamics simulations of a full atomistic Gō model to explore the impact of selected DE-loop mutations (D59P and W60C) on the folding space of protein human β₂-microglobulin (Hβ₂m), the causing agent of dialysis-related amyloidosis, a conformational disorder characterized by the deposition of insoluble amyloid fibrils in the osteoarticular system. Our simulations replicate the effect of mutations on the thermal stability that is observed in experiments in vitro. Furthermore, they predict the population of a partially folded state, with 60% of native internal free energy, which is akin to a molten globule. In the intermediate state, the solvent accessible surface area increases up to 40 times relative to the native state in 38% of the hydrophobic core residues, indicating that the identified species has aggregation potential. The intermediate state preserves the disulfide bond established between residue Cys25 and residue Cys80, which helps maintain the integrity of the core region, and is characterized by having two unstructured termini. The movements of the termini dominate the essential modes of the intermediate state, and exhibit the largest displacements in the D59P mutant, which is the most aggregation prone variant. PROPKA predictions of pK_a suggest that the population of the intermediate state may be enhanced at acidic pH explaining the larger amyloidogenic potential observed in vitro at low pH for the WT protein and mutant forms.     

Effect of Additives on Properties of MgO—ZrO2—C Material

The paper describes the effect of additives Al,Si,SiC and A4C on the expanson of MgO-ZrO2-C material after being coked.Theresults indicate that Al and Si were oxi-dized to form Al2O3 and SiO2 respectively,and then re-acted with CaZrO3 or stabilizer in c-ZrO2 to form calcium aluminate,spinel(MA),dicalcium silicate(C2S) and forsterite (M2S) ,Meznwhile,α-C2S ras transformed to γ-C2S and c-ZrO2 to m-ZrO2 when temperature changed.All the above reactions resulted in the decrease of the amount of Al4C3 and SiC and the increase in bulk volume,which caused the stucture of MgO-ZrO2-C material de-stroyed.Hence,contrary to the MgO-C material,when adding Al,and Si,the MgO-ZrO2-C material would be structurally deteriorated after heat-treatment and its strength and corrosion resistance decreased.