酶解、醚化豌豆淀粉的复配及其玻纤浸润性研究

制备了酶解、醚化豌豆淀粉,并将其作为玻纤浸润剂应用。当在淀粉乳中添加2%的NaCl（占淀粉干基质量）-1时,可提高淀粉乳液在玻璃表面皿上的铺展性,此时酶解及醚化淀粉乳液的表面张力变为最小,分别为41.465 mN·m^-1和40.754 mN·m。通过考察复配淀粉乳在玻璃表面皿的成膜性及经其浸润后玻璃纤维纱线的断裂强度等分析,确定酶-1解、醚化淀粉的最佳复配比为6∶4。最后,在6∶4的复配淀粉中添加2%的NaCl,乳液表面张力由41.195 mN·m降低至-140.163 mN·m,经过其浸润的68 Tex纱线断裂强度能达到4.127 N。     

Starch-derived carbon aerogels with high-performance for sorption of cationic dyes

Environmentally green carbon aerogels have been prepared as adsorbents for dye-containing wastewater. The aerogels were prepared by carbonization of starch aerogels synthesized from soluble starch through a sol-gel process followed by drying at ambient pressure. The Brunauer-Emmett-Teller (BET) surface areas and pore size distribution were measured by N₂ adsorption/desorption, and the surface zeta-potential and microstructure of carbon aerogels were characterized using a scanning electron microscope (SEM) and zeta-potential analyzer. SEM images indicate that the carbon aerogels consist of flakes with side length of 60-120 μm and thickness of 3-4 μm. The flakes are irregular in shape and composed of spherical carbon nanoparticles of 10-30 nm. The carbon aerogels have both microporous and mesoporous structures and exhibit high specific surface areas, the highest value is 1571 m²/g. The mean diameter of the micropores is 0.89 nm and that of the mesopores is 2-10 nm. At pH = 10, the carbon aerogels have a zeta-potential of −40 mV and exhibit high adsorption capacities for cationic dyes, such as crystal violet (CV), methyl violet (MV) and methylene blue (MB), from aqueous solution. The largest adsorption capacities for CV, MV and MB are 1515, 1423 and 1181 mg/g, respectively.     

Microstructure and oxidation resistant of Si–NbSi2 coating on Nb substrate at 800°C and 1000°C

The Si–NbSi₂ composite coating with a smooth surface was successfully prepared on Nb substrate by hot dip silicon-plating (HDS) technology. The composite coating is composed of Si outer layer, NbSi₂ interlayer and Nb₅Si₃ interfacial layer. And the average surface roughness (RSa) and specific surface area growth rate (Sdr) are only 0.275 μm and 2.85%, respectively. The cyclic oxidation test shows that the Si–NbSi₂ composite coating has a very excellent oxidative resistance after oxidation at 800 °C for different times. After oxidation for 40 h, the Δm/S and oxide layer thickness of the coating are only 3.72 mg/cm² and 8 μm, respectively. After oxidation at 1000 °C for 20 h, the coating surface is almost completely covered by a dense SiO₂ layer, the Δm/S and oxide layer thickness of the coating are 7.28 mg/cm² and 15 μm, respectively. The Si–NbSi₂ composite coating presents good self-healing ability and excellent oxidation resistance, which can significantly prolong the service life of bare Nb in oxidation environment.     

Hydrolysis of granular starch at sub-gelatinization temperature using a mixture of amylolytic enzymes

Native granular starches (corn, cassava, mung bean, and sago) were hydrolyzed using a mixture of alpha-amylase and glucoamylase at 35 °C for 24 h. Hydrolyzed starches were analyzed for the degree of hydrolysis and for physicochemical and functional properties. Corn starch showed the highest degree of hydrolysis, as evidenced by the presence of distinct pores penetrating deep into the granules. Enzymatic erosion occurred mainly at the surface for cassava, whereas isolated porous structures were observed in hydrolyzed mung bean and sago starch. The amylose content was significantly lower in all starches except for sago starch. The powder X-ray diffraction of all starches showed no significant changes after hydrolysis, but hydrolyzed starches showed a more crystalline nature. The action of enzymes caused significant changes in some pasting properties and in the swelling/solubility of starches. Evidently, enzymes were able to hydrolyze granular starches to a variable degree at sub-gelatinization temperature, and produced a relatively high degree of conversion.     

不同直链含量热塑性淀粉的制备及性能研究

利用转矩流变仪,以丙三醇为增塑剂对不同来源的淀粉进行改性制备热塑性淀粉（TPS）。采用X射线衍射仪（XRD）、热重分析仪（TG）、水接触角测量仪、傅里叶变换红外光谱仪（FTIR）和扫描电子显微镜（SEM）等对获得的热塑性淀粉进行了表征。结果表明,4种热塑性淀粉均含有颗粒状和颗粒状碎片,并且在热塑性木薯淀粉中所含比例更高;淀粉在增塑过程中达到稳态的扭矩依次为木薯淀粉（23 N·m）>玉米淀粉（21 N·m）>马铃薯淀粉（17.8 N·m）>蜡质玉米淀粉（15.2 N·m）,这与不同种类来源淀粉的直链淀粉比例差异直接相关;不同类型的淀粉与增塑剂形成氢键的能力存在差异,蜡质玉米淀粉的能力最强;4种热塑性淀粉的亲水性依次为热塑性木薯淀粉（75.9 °）>热塑性玉米淀粉（69.2 °）>热塑性马铃薯淀粉（67.9 °）>蜡质玉米淀粉（64.9 °）。     

Zn2+-imprinted porous polymer beads: Synthesis,structure, and selective adsorption behavior for template ion

Zn²⁺-imprinted polymer was synthesized in porous spherical forms via a self-assembled complex between 2,2′-bipyridyl/4-vinylpyridine complexant/functional monomer and Zn²⁺ template ion. Diameters of particles ranged from 250 to 550 μm to enlarge the surface area and thus enhance the adsorption capacity. The presence/absence of the template ion in the preparation of the imprinted polymer was confirmed by EDX spectroscopy, and the physical structure of the particles was investigated using ESEM and BET analysis. The particle and the pore size were controlled by the cross-linker/monomer feed ratio. The adsorption capacity of the imprinted polymers was 210.61 μmol g^?1 for Zn²⁺, while those for Cu²⁺, Ni²⁺, and Pb²⁺, were 37.92 μmol g^?1, 33.02 μmol g^?1, and 9.70 μmol g^?1, respectively. This big discrepancy of the adsorption capacities illustrates the excellent separation selectivity of the imprinted polymers. The adsorption capacity decreased significantly at pH below 4.5, as the polymers are easily protonated. The imprinted particles lost only 10 % of their adsorption ability after 10 repeated uses.     

Fermentative production of L(+)‐lactic acid from starch hydrolyzate and corn steep liquor as inexpensive nutrients by batch culture of Enterococcus faecalis RKY1

BACKGROUND: Attempts were made to determine the lactic acid production efficiency of novel isolate, Enterococcus faecalis RKY1 using four different starches (corn, tapioca, potato, and wheat starch) with different concentrations (50, 75, 100, and 125 g L^?1) and corn steep liquor as an inexpensive nitrogen source. RESULTS: The yield of lactic acid from each starch was higher than 95% based on initial starch concentrations. High lactic acid concentration (129.9 g L^?1) and yield (1.04 g‐lactic acid g^?1‐starch) were achieved faster (84 h) from 125 g L^?1 of corn starch. Among the starches used, tapioca starch fermentation usually completed in a shorter incubation period. The final dry cell weight was highest (7.0 g L^?1) for the medium containing 75 g L^?1 of corn starch, which resulted in maximum volumetric productivity of lactic acid (3.6 g L^?1 h^?1). The addition of 30 g L^?1 corn steep liquor supplemented with a minimal amount of yeast extract supported both cell growth and lactic acid fermentation. CONCLUSION: Enterococcus faecalis RKY1 was found to be capable of growing well on inexpensive nutrients and producing maximum lactic acid from starches and corn steep liquor as lower‐cost raw materials than conventionally‐used refined sugars such as glucose, and yeast extract as an organic nitrogen source in laboratory‐scale studies. These fermentation characteristics are prerequisites for the industrial scale production of lactic acid. Copyright © 2008 Society of Chemical Industry     

Zirconia nano-powders with controllable polymorphs synthesized by a wet chemical method and their phosphate adsorption characteristics & mechanism

Adsorption is a simple and efficient phosphorus removal method used to control the eutrophication of water bodies. A simple and gentle atmospheric pressure hydrothermal method by adjusting the dosage of ammonium chloride and sodium hydroxide was used to synthesize amorphous, monoclinic, and tetragonal zirconia nano-powders with high specific surface areas (383.91 m²/g, 330.01 m²/g, and 234.36 m²/g) and particle size of about 40 nm for phosphate adsorption. When pH = 6.3, the phosphate adsorption capacity of the amorphous monoclinic phase and the tetragonal phase respectively reached 102.58 mg P/g, 68.11 mg P/g, and 37.25 mg P/g and the adsorption process of the three crystal forms of zirconia powders conformed to the Langmuir adsorption model. In the first 2 min of rapid adsorption, amorphous zirconia completed 76.23% of the adsorption process and the monoclinic phase also completed more than 60%. The adsorption process of the three crystal forms of zirconia was completed within 240 min and conformed to the pseudo-second-order kinetic model. Their adsorption characteristics of the three crystal forms of zirconia decreased with the increase in pH. While the pH was above than the isoelectric point of the solution, the adsorption capacity was significantly reduced. The large specific surface area and high hydroxyl content of the zirconia nano-powder made a great contribution to the adsorption process.     

Characterization of different starch types for their application in ceramic processing

Starch is a frequently used pore-forming agent in ceramic technology. Moreover, it can take over the function of a body-forming agent in a recently developed process, called starch consolidation casting. Upon firing the starch polymers are burnt out without residues and leave a pore structure determined by the type of starch applied. In this paper, five commonly available starch types (potato, wheat, tapioca, corn and rice starch) are characterized with respect to size and shape. Size distributions are measured via laser diffraction and microscopic image analysis. Rice starch is found to be the smallest type (median size 4.4–4.8 μm), potato starch the largest (median size 46–49 μm) and the other types intermediate (median size 12–21 μm). The distribution is narrow for corn and tapioca starch (span approximately 1.1), while potato, wheat and rice starch are relatively polydisperse (span approximately 1.35–1.65). The shape of the starch granules is most anisometric for potato starch (average aspect ratio 1.3–1.4). All other starch types, although possibly of polyhedral shape (tapioca, corn and rice starch), are more isometric, i.e. very close to an average aspect ratio of 1.     

Corrosion inhibition of mild steel in acidic media by Basic yellow 13 dye

The inhibition performance of Basic yellow 13 dye on mild-steel corrosion in hydrochloric acid solution was studied at 25 °C using weight loss and electrochemical techniques. The effect of inhibitor concentration on inhibition efficiency has been studied. Inhibition efficiency increased with increase of Basic yellow 13 concentration. The results showed that this inhibitor had good corrosion inhibition even at low concentrations (95% for 0.005 M Basic yellow 13) and its adsorption on mild-steel surface obeys Langmuir isotherm. ΔG _ads was calculated and its negative value indicated spontaneous adsorption of the Basic yellow 13 molecules on the mild-steel surface and strong interaction between inhibitor molecules and metal surface. The value of ΔG _ads was less than 40 kJmol⁻¹, indicating electrostatic interaction between the charged inhibitor molecules and the charged metal surface, i.e., physical adsorption.     

Synthesis and Surface Activities of Novel Monofluoroalkyl Phosphate Surfactants

Two novel environmentally friendly fluorinated surfactants, disodium monofluoroalkyl phosphates were synthesized using phosphorus pentoxide, i.e. H(CF₂)₆CH₂OPO(ONa)₂ and H(CF₂)₆CH₂OCH₂CH₂OPO(ONa)₂. The novel synthesized fluorinated surfactants have a high thermal stability on the basis of Thermogravimetric Analysis. Their surface properties were also examined with the aim to have similar surface tensions of dilute aqueous solutions when compared with the conventional fluorocarbon surfactants, ammonium perfluorooctanoate. The two synthesized monofluoroalkyl phosphates can respectively reduce the surface tension of water to 23.73 mN/m at 78.3 mmol/L and 21.38 mN/m at 20.93 mmol/L. In addition, the Krafft points are both below 0 °C.     

Comparative disintegrant activities of breadfruit starch and official corn starch

A Comparative evaluation of starch powder extracted from breadfruit (Artocarpus communis, Frost) as tablet disintegrant was made with corn starch BP using a 2 × 4 factorial experiment in a randomized complete block design. Two factors (type of starch: 2 i.e. breadfruit and corn) at four levels (concentrations of starch disintegrant: 4 i.e. 2.5%, 5%, 7.5% and 10%) were studied. One (1) kilogram batches of paracetamol granules containing various concentrations of endo-disintegrant or exo-disintegrant were prepared by the wet granulation method in a combined mixer-granulator, using polyvinyl pyrrolidone solution as binder. Tablets were tested for disintegration, dissolution and physical qualities following the British Pharmacopoeia (BP) compendial procedures.At the compression force of 1 tonne, corresponding to average packing fraction of 0.92, all formulations containing breadfruit and corn starch exo-disintegrants passed the official disintegration time limit of ≤ 15 min and quantity dissolved (Q₃₀) of ≥ 80% in 30 min. As endo-disintegrant however, only corn starch at 5% and 10% w/w and breadfruit at 10% passed the BP limit test. Generally, the rank order of effectiveness of disintegrant was Corn_exo ≈ Breadfruit_exo > Corn_endo > Breadfruit_endo. The observed concentration-dependent difference in disintegrant effectiveness is ascribed to the differences in their hydration capacity and effective tablet porosity. Contrary to faster disintegration suggested by its higher hydration capacity, breadfruit starch formulations showed longer disintegration time than corn, attributable to the higher density of breadfruit formulations which appears to retard entry of disintegration fluid into the tablet. However, the dissolution profiles (Q₃₀) were comparable (p > 0.05).Breadfruit starch powder appears to be a suitable substitute for official corn starch only as exo-disintegrant in paracetamol tablet formulation. In that form, it not only produced rapid tablet break-up and drug dissolution, it also improved tablet crushing strength.     

Improved field emission properties of carbon nanotubes decorated with Ta layer

The field emission (FE) properties of vertically aligned carbon nanotube (CNT) arrays having a surface decorated with Ta layer were investigated. The CNTs with 6 nm thickness of Ta decoration showed improved FE properties with a low turn-on field of 0.64 V/μm at 10 μA/cm², a threshold field of 1.06 V/μm at 1 mA/cm² and a maximum current density of 7.61 mA/cm² at 1.6 V/μm. After Ta decoration, the increased emission centres and/or defect sites on the surface of CNTs improved the field enhancement factor. The work function of CNTs with Ta decoration measured with ultraviolet photoelectron spectroscopy decreased from 4.74 to 4.15 eV with increasing Ta thickness of 0–6 nm. The decreased work function and increased field enhancement factor were responsible for the improved FE properties of the vertically aligned CNTs. Moreover, a significant hysteresis in the cycle-testing of the current density with rising and falling electric field process was observed and attributed to the adsorption/desorption effect, as confirmed by the photoelectron spectrum.     

Light‐weight thermal insulating fly ash cenosphere ceramics

Light weight fly ash cenosphere (FAC) ceramic composites were developed by simple slip casting method. Thermal properties, Bulk density, Microstructure, flexural strength, and phase analysis of the FAC ceramic composites were measured. The results proved that the FAC have ability to lower bulk density and thermal conductivity effectively. The lowest thermal conductivity achieved for FAC ceramic composites (0.27 W/m.K) was further reduced 0.21 W/m.K by adding combustible additives ie activated charcoal and corn starch. The flexural strength, bulk density and thermal conductivity of FAC ceramic composites reduced consistently with an increase in FAC content. The maximum flexural strength of 13.45 MPa was achieved with 50% FAC and the minimum flexural strength of 4.07 MPa was obtained with 80% FAC. The open porosity increased from 35.51% to 43.76% and 38.19% with an addition of 15% activated charcoal and corn starch, respectively, when compared to no additives. The bulk density of 699, 619, and 675 kg/m³ was achieved with 80% FAC, 80% FAC with the addition of 15% activated charcoal and corn starch, respectively. The 80% FAC ceramic composite shows low thermal expansion coefficient 6.54 × 10^?6/°C at the temperature of 50°C then it varies between 3.7 and 5 × 10^?6/°C in the temperature range above 100°C. These results prove that the developed light weight FAC ceramic are excellent low‐cost thermal insulating materials.     

UV-polymerisable,phosphorus-containing,flame-retardant surface coatings for glass fibre-reinforced epoxy composites

A vinyl phosphonic acid based flame retardant coating has been applied on the surface of a glass-fibre reinforced epoxy (GRE) composite substrate using a UV polymerisation technique. On exposure to heat the poly (vinyl phosphonic acid) (PVPA) coating thus obtained, intumesces and acts as a thermal insulator, providing active fire protection to the composite structure. Samples with ∼300 and 500 μm thick coatings were prepared. The fire performance of the coated GRE composite was studied by cone calorimetry at 35 and 50 kW/m² heat fluxes. While the sample with ∼500 μm thick coating did not ignite at both heat fluxes, the one with the ∼300 μm thick coating ignited at 50 kW/m², however the time-to-ignition was delayed from 60 s in the uncoated sample to 195 s and the peak heat release rate reduced from 572 kW/m² to 86 kW/m². The coatings did not peel off when subjected to a tape pull test and resisted cracking/debonding during an impact drop test of up to 5 J energy. However, the coatings are hydrophilic, showing significant mass loss in a water soak test. The improvement of the hydrophobicity of these coatings is a focus of our future research.     

Porosity and pore size control in starch consolidation casting of oxide ceramics—Achievements and problems

The possibilities and limits of porosity and pore size control via starch consolidation casting (SCC) are discussed from a principal point of view. The results for alumina ceramics indicate that porosity control between 25 and 50% is feasible, while lower and higher porosities are difficult to achieve by SCC. The main factor of pore size control is the selected starch type, although swelling should be taken into account for a more precise size control. Of the starch types investigated here, potato starch is the largest (resulting in pore sizes of 50 μm and higher) and corn starch is the smallest (14 μm), while wheat starch is intermediate (20 μm). A quantitative comparison of pore size results, however, is complicated by Wicksell's problem and (in the case of potato and wheat starch) the anisometric shape (median aspect ratios of 1.3 and 2.0 for prolate and oblate shape, respectively).     

Removal of basic yellow cationic dye by an aqueous dispersion of Moroccan stevensite

The aim of this study was to investigate the adsorption of basic yellow, a cationic dye, from aqueous solution by natural stevensite, with 104 m²/g of specific surface area. The kinetics and the effects of several experimental parameters such as the pH of the solution, adsorbent dose and initial dye concentration were researched using a batch adsorption technique. The results showed that an alkaline pH favoured basic yellow adsorption and the adsorption reached equilibrium in about 20 min. It was concluded that the adsorption process was governed by the electrostatic interaction. The isothermal data were fitted by means of Langmuir and Freundlich equations, and a monolayer adsorption capacity of 454.54 mg/g was calculated. Finally, a good agreement was found between the pseudo-second order model and the experimental data. A high maximum adsorption capacity was obtained (526 mg/g) and a maximum surface density of ~ 9 dye molecules/nm² was estimated, involving a columnar arrangement of the adsorbed molecules.     

Synthesis and Properties of Novel Double-Tail Trisiloxane Surfactants with High Spreading Ability

A new type of double-tail trisiloxane surfactants of the general formula R¹NR²CH₂CH(OH)CH₂O(CH₂CH₂O)xCH₃ (x = 8.4, 12.9, 17.5, 22; R ¹ = Me₃SiOSiMe(CH₂)₃OSiMe₃, R ² = CH₂CH(OH)CH₂OR³, R ³ = CH₂CH(C₂H₅)CH₂(CH₂)₂CH₃) has been synthesized by reacting single-tail trisiloxane surfactants with 2-ethylhexyl glycidyl ether. Their structures were characterized with ¹H-NMR and ¹³C-NMR spectroscopy. These double-tail trisiloxane surfactants reduce the surface tension of water to less than 24 mN/m at a level of 10⁻⁵ mol/L. The spreading ability (SA) of the double-tail trisiloxane surfactant solution on Parafilm (or Ficus microcarpa leaf) surfaces is better than that on polyethylene terephthalate surface. The SA of the solution of the double-tail trisiloxane surfactants 1J with average ethoxy units of 8.4 is far better than the others, and its solution (5.0 × 10⁻³ mol/L) possesses an SA value of over 15 within 10 min on Parafilm and Ficus microcarpa leaf surfaces. The surface tension values of aqueous solutions (1.0 × 10⁻³ mol/L) of the double-tail trisiloxane surfactants 1J are still less than 25 mN/m over 21 days in an acidic environment (pH 4.0) and 139 days in an alkaline environment (pH 10.0), respectively. It is suggested that the SA and hydrolysis resistance of double-tail trisiloxane surfactants are able to be improved by changing the structure of the hydrophobic group, such as increasing the molar ratio of methyl to methylene.     

Preparation of nano-Ag-Bi2WO6–TiO2/starch bionanocomposite membranes and mechanism of enhancing visible light degradation of ethylene

Ag–Bi₂WO₆–TiO₂ (ABT) ternary composite photocatalyst was prepared using solvothermal and surface deposition method. Then, the nano photocatalyst was doped into the starch film liquid through internal loading method, and finally, ABT/starch composite film was constructed using tape casting method for visible light catalytic degradation of ethylene. Characterize and analyze the structure and physical properties of nano ABT/starch composite membranes prepared with different ABT loading amounts, and optimize the reaction conditions (ABT addition amount, light intensity, initial concentration of ethylene) on the visible light catalytic degradation performance for ethylene of the composite membrane. The results show that the nano ABT particles and starch molecules have good biocompatibility, and they can be well fused to form a film, without changing the crystal structure of ABT and generating other chemical bond. The results of photocatalytic degradation of ethylene showed that when the loading amount of ABT was 5 wt%, the light intensity was 60.5 mw/cm², and the initial concentration of ethylene was 0.15 mg/L, the ABT/starch film had the best ethylene degradation performance, with a K′ value of 5.6111 × 10⁻⁴ min⁻¹, which is 17.9 times that of the blank starch film. Under the optimal preparation conditions, the thickness, tensile strength, elongation at break of the starch composite film is 168.33 μm, 5.01 Mpa, 32.4%, respectively, and the maximum thermal decomposition temperature is 320.5 °C, which meets the requirements for food packaging materials. After 4 cycles, the catalytic degradation of ethylene by starch composite membrane only decreased by 13.98%, indicating good reusability.     

Experimental investigation of ultrasonic-vibration polishing of K9 optical glass based on ultrasonic atomization

K9 optical glass has an important position in the field of optical material because of its excellent chemical stability and optical projection. The hard and brittle characteristics of K9 optical glass make conventional processing difficult and time-consuming. A non-conventional hybrid polishing system combining ultrasonic atomization (UA) spraying method and axial ultrasonic vibration was developed for processing K9 optical glass. This system utilizes the high-frequency vibration characteristics of ultrasonic vibration technology: On the one hand, the ultrasonic atomization spraying method is used to generate evenly distributed atomized droplets for polishing, on the other hand, the axial ultrasonic vibration of the polishing tool provides impact kinetic energy for the free abrasive particles. Mechanical polishing (MP), ultrasonic-assisted polishing (UVP), mechanical polishing under ultrasonic atomization spraying (UA-MP) and ultrasonic vibration polishing under ultrasonic atomization spraying (UA-UVP) were carried out on K9 optical glass. The material removal rate (MRR), material removal depth (MRD), surface quality and surface micromorphology of the polished workpieces were also analyzed and compared. The experimental results showed that the best surface was obtained at UA-UVP (A_Ⅰ = 9 μm) with MRR of 0.0994 mm³/min, material removal depth of 26.816 μm, the Ra and Sa values were 0.028 μm and 0.033 μm respectively. Meanwhile, no obvious pits and scratches were observed on the micromorphological surface. Ultrasonic atomization contributes to even material removal from the polished surface and axial ultrasonic vibration of the polishing tool has a significant effect in improving the polishing characteristics, which provides the experimental basis for applying ultrasonic vibration technology in polishing.