交联糖化酶聚集体的制备

为了克服游离糖化酶的部分缺点,将游离糖化酶用合适的沉淀剂沉淀后,再用戊二醛作为交联剂进行交联,制备了新型的固定化糖化酶-交联糖化酶聚集体。研究结果表明,糖化酶最适聚集条件为:pH5.6,20℃,5g/L的糖化酶液中加入叔丁醇沉淀,可获得比较理想的糖化酶聚集体;最适交联条件为:向糖化酶聚集体中加入10%戊二醛水溶液交联120min,再经离心、洗涤数次后即得交联糖化酶聚集体,酶活力为游离糖化酶的40.4%。     

沥青质聚集体的解聚分离方法综述和探析

沥青质在原油、渣油体系中常以分子聚集体的形式存在,要研究沥青质的分子组成和结构以及含沥青质重油的加工,基础是要实现沥青质分子聚集体的解聚、分离。基于此,针对沥青质分子聚集体中存在的分子间相互作用（力）,从良溶剂稀释、消除聚集作用位点、适度热作用、超声波作用及碰撞诱导解离等五个方面阐述了沥青质分子聚集体解离方法及进展,进一步介绍了基于沥青质分子极性、分子尺寸、酸碱性以及反应性等方面开展沥青质分子水平分离的方法及进展。     

Preparation of spherical aggregates of taro starch granules

Taro starch spherical aggregates were prepared by including a spray drying step in a conventional pilot plant-scale starch isolation procedure. The aim of this study was to characterize these spherical aggregates. The procedure was repeated three times to verify the spherical aggregates formation, which was shown by scanning electron microscopy. Amylose was not be detected in the aggregates, and a protein content of 4.5 g/100 g was recorded. Aggregation of taro starch granules did not affect the X-ray diffraction pattern. The maximum peak viscosity of the aggregate preparation was obtained at a relatively high temperature (i.e. start of the temperature holding step). The phase transition of taro starch aggregates in excess water showed high temperatures, with low molecular reorganization during storage. During water retention capacity (WRC) and solubility tests, taro starch aggregates were stable until 70 °C. The spray drying conditions used produced spherical aggregates of taro starch that presented physicochemical and functional characteristics with potential for encapsulation of substances.     

Modulation of rheological properties by heat-induced aggregation of whey protein solution

Heat-induced protein aggregation at low protein concentrations generally leads to higher viscosities. We here report that aggregated protein can yield weaker gels than those from native protein at the same concentration. Aggregated protein was produced by heating a solution of whey protein isolate (WPI) at 3% and 9% w/w. The higher protein concentration resulted in a larger aggregate size and a higher intrinsic viscosity. The protein fraction in native WPI had the smallest size and the lowest intrinsic viscosity. The same trend was observed for the shear viscosity after concentrating the suspensions containing aggregates to around 15% w/w. Suspensions containing aggregates that were produced from a higher concentration possessed a higher viscosity. After reheating the concentrated suspensions, the suspension from the 9% w/w aggregate system produced the weakest gel, followed by the one from 3% w/w, while the native WPI yielded the strongest gel. Reactivity of the aggregates was also an important factor that influenced the resulting gel properties. We conclude that aggregation of whey protein solution is a feasible route to manipulate the gel strength of concentrated protein systems, without having to alter the concentration of the protein.     

Stochastic service-life modeling of chloride-induced corrosion in recycled-aggregate concrete

The development and implementation of a stochastic service-life model for chloride-induced corrosion in reinforced recycled-aggregate concrete is presented in this work. The 1D model accounts for recycled aggregates that have been initially contaminated with chlorides from previous in-service exposure. Using a probabilistic approach, the model is employed to predict the service life of normal- and recycled-aggregate reinforced concrete with and without aggregate pre-contamination. Specifically, the effect of (a) type and replacement ratio of reclaimed aggregate, (b) chloride boundary conditions, (c) initial aggregate chloride concentration, and (d) thickness of contaminated aggregate shells on time to corrosion cracking was investigated herein. Results suggest that certain levels of contamination may be permissible in the design of reclaimed-aggregate reinforced concrete structures. Furthermore, quality control standards that limit thresholds of recycled aggregate replacement ratios and aggregate purity should be based on anticipated exposure conditions and old mortar thicknesses rather than initial degrees of aggregate contamination.     

Development of high-performance heavy density concrete using different aggregates for gamma-ray shielding

Primary and secondary containment structures are the major components of the nuclear power plant (NPP). The performance requirements of the concrete of containment structures are mainly radiological protection, structural integrity and durability, etc. For this purpose, high-performance heavy density concrete with special attributes can be used. The aggregate of concrete plays an essential role in modifying concrete properties and the physico-mechanical properties of the concrete affect significantly on its shielding properties. After extensive trials and errors, 15 concrete mixes were prepared by using the coarse aggregates of barite, magnetite, goethite and serpentine along with addition of 10% silica fume (SF), 20% fly ash (FA) and 30% ground granulated blast-furnace slag (GGBFS) to the total content of OPC for each mix. To achieve the high-performance concrete (HPC- grade M60), All concrete mixes had a constant water/cement ratio of 0.35, cement content of 450 kg/m³ and sand-to-total aggregate ratio of 40%. Concrete density has been measured in the case of fresh and hardened. The hardened concrete mixes were tested for compressive strength at 7, 28 and 90 days. In some concrete mixes, compressive strength was also tested up to 90 days upon replacing sand with the fine portions of magnetite, barite and goethite. The attenuation measurements were performed by using gamma spectrometer of NaI (Tl) scintillation detector. The utilized radiation sources comprised ¹³⁷Cs and ⁶⁰Co radioactive elements with photon energies of 0.662 MeV for ¹³⁷Cs and two energy levels of 1.173 and 1.333 MeV for ⁶⁰Co. Some shielding factors were measured such as half-value layer (HVL), tenth-value layer (TVL) and linear attenuation coefficients (μ). Experimental results revealed that, the concrete mixes containing magnetite coarse aggregate along with 10% SF reaches the highest compressive strength values exceeding over the M60 requirement by 14% after 28 days of curing. Whereas, the compressive strength of concrete containing barite aggregate was very close to M60 and exceeds upon continuing for 90 days. The results indicated also that, the compressive strength of the high-performance heavy density concrete incorporating magnetite as fine aggregate was significantly higher than that containing sand by 23%. Also, concrete made with magnetite fine aggregate improved the physico-mechanical properties than the corresponding concrete containing barite and goethite. Therefore, high-performance concrete incorporating magnetite as fine aggregate enhances the shielding efficiency against γ-rays.     

Supramolecular Chiral Aggregates Exhibiting Nonlinear CD–ee Dependence

Although a linear relationship between the optical activity (normally the CD signal) and the enantiomeric excess (ee) of chiral auxiliaries has been the most commonly observed dependence in dynamic supramolecular helical aggregates, positive nonlinear CD–ee dependence, known as the “majority-rules effect” (MRE), indicative of chiral amplification, has also been well documented and to some extent understood. In sharp contrast, the negative nonlinear CD–ee dependence has been much less reported and is not well understood. Here, the state of the art of both the positive and negative nonlinear CD–ee dependence in noncovalently bound supramolecular helical aggregates is summarized, with the hope that the vast examples of supramolecular aggregates showing positive nonlinear dependence, in terms of the methods of investigations, variations in the structure of the building block (single species or multiple species), and theoretical modeling using the mismatch penalty energy and helix reversal penalty energy, would help to guide the design of building blocks to form aggregates showing negative nonlinear dependence, and thus to understand the mechanisms. The potential applications of those functional supramolecular aggregates are also discussed.     

Isolation of peanut protein aggregates using aqueous extraction processing combined with membrane separation

A two-stage microfiltration and ultrafiltration (MF/UF) for peanut protein recovery and water recycling from aqueous extraction processing (AEP) were investigated. Peanut protein aggregates and alkaline water were obtained using flat and wound MF/UF and alkaline water recycled in AEP. With this approach, most of the wastewater could be recycled to produce reusable water to solve wastewater problems in aqueous oil extraction processing from oilseeds. The result showed that a little oil and protein were lost (1.21% and 4.35%, respectively) during the recycling of permeate in AEP, which was still acceptable. Peanut protein aggregations (PPAs) were characterised by analysis with Fourier-transform infrared spectroscopy (FTIR), sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE), high-performance gel filtration chromatography (HPGFC) and binding force analysis. Solubility analysis suggested that PPA had molecular structures with more hydrophobic groups on the surface than in the peanut protein isolate (PPI). In vitro, PPA was digested by both pepsin and trypsin more than PPI. FTIR profiles demonstrated there were more β-sheet and less α-helix in PPA, which means much more aggregation. In addition, binding force analysis showed hydrophobic interaction was the major force that restricted dissolution of PPA and disulfide bonds were of second importance, which provided a possible physical treatment opportunity for improving the solubility of PPA.     

Environmental impact estimation of ceramic lightweight aggregates production starting from residues

Within a circular economy approach, this study investigates the environmental impact of lightweight aggregates (LWAs) produced starting from different mixes of different clays with brewery sludge and cattle bone flour ash (CBA), used as poring and fertilizing agents, respectively. The environmental impact was evaluated by means of release tests, insulation capacity, carbon footprint (CFP), and particulate matter emission during pellet firing. Release tests representative of LWAs realistic application showed very high release of phosphate and satisfactory release of potassium. The thermal insulation of the LWAs was tested by thermal imaging camera and resulted highly variable depending on the composition, with the mix containing CBA performing best. This latter composition leads also to the smallest CO₂ equivalent emission, due to the calorific power of CBA, allowing lower consumption of fossil fuels during the LWA production. Finally, total particulate emissions during the thermal treatment resulted similar in terms of mass for all mixes, while differences in terms of particle morphology and composition occurred. Samples containing residue resulted with a quite good release behavior, CFP, and insulation properties, but higher emission of particles, particularly when glass is added.     

Ultranarrow Bandwidth Organic Photodiodes by Exchange Narrowing in Merocyanine H‐ and J‐Aggregate Excitonic Systems

Ultranarrowband organic photodiodes (OPDs) are demonstrated for thin film solid state materials composed of tightly packed dipolar merocyanine dyes. For these dyes the packing arrangement can be controlled by the bulkiness of the donor substituent, leading to either strong H‐ or strong J‐type exciton coupling in the interesting blue (H‐aggregate) and NIR (J‐aggregate) spectral ranges. Both bands are shown to arise from one single exciton band according to fluorescence measurements and are not just a mere consequence of different polymorphs within the same thin film. By fabrication of organic thin‐film transistors, these dyes are demonstrated to exhibit hole transport behavior in spin‐coated thin films. Moreover, when used as organic photodiodes in planar heterojunctions with C₆₀ fullerene, they show wavelength‐selective photocurrents in the solid state with maximum external quantum efficiencies of up to 11% and ultranarrow bandwidths down to 30 nm. Thereby, narrowing the linewidths of optoelectronic functional materials by exciton coupling provides a powerful approach to produce ultranarrowband organic photodiodes.