Granule structural,crystalline, and thermal changes in native Chinese yam starch after hydrolysis with two different enzymes–α‐amylase and gluco‐amylase

Starch extracted from Chinese yam was characterized by scanning electron microscope (SEM), X‐ray powder diffractometer (XRD), and differential scanning calorimeter (DSC) in the process of enzymatic hydrolysis. Yam starch was digested by α‐amylase and gluco‐amylase for different lengths of time, respectively, and two different enzymatic hydrolysis results were compared. The most notable phenomenon revealed by SEM after α‐amylase hydrolysis was the formation of the cavum in the center of the starch granules, while after gluco‐amylase hydrolysis, the outer layer of the granules was peeled off and then some granules even broke into pieces. The XRD of the two enzyme hydrolyzed starches revealed the crystal type of the starch changed from typical C‐type XRD pattern to the representative A‐type pattern in the process of enzymatic hydrolysis. The above results also demonstrated that the partially B‐type polymorph was more easily degraded than A‐type. The thermal result showed that the modified yam starches by both enzymes exhibited increased peak gelatinization temperatures (T_p) and decreased gelatinization enthalpy (ΔH).     

Comparison of the physicochemical and functional properties of Aconitum carmichaeli and Aconiti lateralis Preparata starches

Aconitum, an important toxic traditional Chinese medicine, has been widely used in clinical practice. Owing to its toxicity, it should be processed before application. Aconiti lateralis Preparata (ALP) is one of the most important commercial processed products of Aconitum. The object of this work is to study the physicochemical and functional properties of Aconitum and ALP starches. The results revealed that AM content changed, transforming from 37.5 to 27.5% after processing. The shape of Aconitum starch granules also changed from spherical or oval with sizes of 5–15 µm to irregular and polygonal with sizes of 30–60 µm. The crystallinity of Aconitum decreased from 38.7 to 23.0% after processing. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) were determined using DSC. T_o, T_p and T_c decreased from 52.9 to 48.6, 66.9 to 58.9, and 82.2 to 69.3°C, respectively. Aconitum starch showed higher ΔH_gel values (1.6 J/g), while the ALP starch showed lower values (0.4 J/g).     

京津冀地区水-能源-粮食系统安全耦合协调发展特征评价

以京津冀地区为研究区域,选取28个代表性指标,利用层次分析法构建水-能源-粮食耦合安全综合指标体系,运用耦合协调度模型和障碍度模型分析2000—2020年水-能源-粮食系统耦合安全性和影响因素。研究结果表明：京津冀地区水安全、能源安全和粮食安全系统综合评价指数呈整体上升的趋势,其浮动范围为0.3~0.7;水-能源-粮食系统耦合协调度年际间均呈上升趋势,北京市耦合协调度最高,河北省耦合协调度较低;人均水资源量、废水中COD排放量、人均能源消费量和亩均农用机械总动力为京津冀地区主要障碍因子。未来北京应调整用水结构、挖掘节水潜力。天津市和河北省要注重优化能源消费结构,进行低碳技术创新,加大脱碳步伐,其中河北省农业发展需要进一步采取节水灌溉措施、减少农作物受灾面积。     

Hierarchical Graphene‐Based Films with Dynamic Self‐Stiffening for Biomimetic Artificial Muscle

Biological tissues such as muscle cells can adapt their structural and mechanical response upon external mechanical stimuli. Conversely, artificial muscles, intended to reproduce the salient functional features of biological muscles, usually undergo mechanical fatigue when subjected to dynamic stress. Besides passively improving the resilience to dynamic loads, here, it is reported that macroscopic films based on graphene and its chemical derivate exhibit an increase in modulus by up to 84% after subjected to a low‐amplitude (0.1%) dynamic tension. Through a combination of experimental testing and molecular dynamics simulations, the unique self‐stiffening behavior is attributed to the straightening and reorientation of graphene sheets and is further tuned through tailoring interlayer adhesion. Meanwhile, artificial muscles based on graphene films are designed and interestingly improved stiffness of our muscle materials after “training” are demonstrated. These results help to harness the stiffening mechanism and can be useful for the development of adaptable structural materials for biomechanical applications.     

Viewpoints [computing in the 1990s]

Fifteen academic and industry leaders share their views on current and future computer and related technology. They discuss Europe 1992 and its impact on information technology, 25 years of MITI and its influence on computing research in Japan, concurrent engineering, the scientific data decade, information systems, superconductivity and computing technology, semiconductor technology at middle age, past and future computer networks, testing and design verification of electronic components, operating systems in the year 2000, data parallel computing, computer-aided software prototyping, and object-oriented software technology     

Compositional semantics of a real-time prototyping language

The formal semantics of a prototyping language for hard real-time systems, PSDL, is given. PSDL provides a data flow notation augmented by application-orientation timing and control constraints to describe a system as a hierarchy of networks of processing units communicating via data streams. The semantics of PSDL are defined in terms of algebraic high-level Petri nets. This formalism combines algebraic specifications of abstract data types with process and concurrency concepts of Petri nets. Its data abstraction facilities are used to define the meaning of PSDL data types, while high-level Petri nets serve to model the casual and timing behavior of a system. The net model exposes potential concurrency of computation and makes all synchronization needs implied by timing and control constraints explicit and precise. Time is treated as state of clocks, and clocks are modeled as ordinary system components. The net semantics provides the basis for applying analysis techniques and semantic tools available for high-level Petri nets     

Formal methods: promises and problems

Successfully applying formal methods to software development promises to move us closer to a true engineering discipline. The authors offer suggestions for overcoming the problems that have hindered the use of formal methods thus far     

On merging software extensions

Summary The problem of combining independent updates to a program is examined in the context of applicative programs. A partial semantic merge rule is given together with the conditions under which it is guaranteed to be correct, and the conditions under which a string merge corresponds to a semantic merge are examined. The theoretical work reported here contains initial steps towards a solution of the software merging problem and is not sufficient for producing a practical system.     

Artificial bee colony algorithm with an adaptive search manner and dimension perturbation

Neural Computing and Applications - Artificial bee colony (ABC) can effectively solve some complex optimization problems. However, its convergence speed is slow and the exploitation capacity is...