Photoresponsive peptide and polypeptide systems: part II. Photochromism of poly(l-ornithine) containing various azo-contents in side chains

Poly(L-ornithine)s having various azo-contents in the side chains were synthesized by the water-soluble carbodiimide procedure. The photochemical properties of the polypeptides poly[N^δ-p-(phenylazo)benzoyl-L-ornithine] (PPABLO) containing 3–77 mol% azobenzene were investigated by absorption and circular dichroism spectroscopy in hexafluoro-2-propanol (HFIP) or water, and in HFIP-water or methanol-water solvent mixtures. The photochromism of the dichroic bands of the PPABLOs containing 20–77 mol% azobenzene in the visible and ultraviolet wavelength regions was found to be mostly reversible as a function of irradiation time at different wavelengths due to the photostationary state (above 80% trans-cis photoisomerization) of the azo aromatic moieties. The PPABLO containing 3.2 mol% azobenzene in water exhibited conformational changes from random coil to helix by the addition of methanol or sodium dodecyl sulphate (SDS). The photo-induced conformational change was observed in HFIP-water-SDS solvent mixtures, while no conformational change was seen in water and HFIP-water solvent mixtures.     

Volatile organo-halogen trace analysis in beverages by thin-layer headspace enrichment and electron-capture gas-chromatography

Applicability of thin-layer headspace (TLHS) procedure giving an aqueous concentrate and also classical purge and trap (PT) in off-line mode to isolate and enrich volatile organohalogen compounds in common beverages was tested. Both enrichment tech-niques were used in combination with gas chromatography – electron capture detection (GC-ECD). TLHS, combined with direct aqueous injection (DAI)-GC-ECD, proved applicable in the determination of volatile organohalogen compounds in all studied beverages, while the PT in a version with no preliminary sample pre-treatment was of limited applicability. Detection limits of the TLHS-based procedure were in the order of 1 ppt. Content of volatile organohalogen compounds in a number of beverages available on the Polish market including mineral waters, beers, juices, carbonated and non-carbonated soft drinks, etc. was determined by means of TLHS-DAI-GC-ECD.     

国际乳业的热点论题：蛋白质标准化

介绍了蛋白质的标准化这一国际乳品界正热的研究和讨论题目，综述了蛋白质标准化的必要性和世界上目前采用的方法，展望了膜技术在蛋白质标准化上的应用前景。     

Finite Element Analysis of a Moving Boundary Value Problem

A finite element formulation and the solution of a set of nonlinear coupled heat and mass transfer equations for a two-phase system with a moving evaporation interface is presented. The interface condition takes into account the moisture transfer balance at the moving boundary. The finite element results were compared with existing results for a single phase system for model validation. In the two-phase system, the movement of evaporation front has an appreciable effect on the temperature and moisture distribution inside the porous medium during drying. The effect of the nondimensional heat of vapourization parameter γ on the evaporation front, temperature and moisture distribution in porous medium was studied. The higher the value of γ, the slower is the movement of the evaporation front. The temperature decreased and the moisture content increased as the nondimensional vapourization parameter γ increased. This model has potential applications in studying the heat and mass transfer characteristics in food and biomaterials.     

Hierarchical production control for a flow shop with dynamic setup changes and random machine breakdowns

In this paper, we study a manufacturing system consisting of two machines separated by two intermediate buffers, and capable of producing two different products. Each product requires a constant processing time on each of the machines. Each machine requires a constant non-negligible setup change time from one product to the other. The demand rate for each product is considered to be piecewise constant. Each machine undergoes failure and repair. The time-to-failure and time-to-repair are exponentially distributed random variables. The setup change and processing operations are resumable. We model our system as a continuous time, continuous flow process. An optimal control problem is formulated for the system to minimize the total expected discounted cost over an infinite horizon. To determine the optimal control policy structure, a discrete version of the problem is solved numerically using a dynamic programming formulation with a piecewise linear penalty function. A real-time control algorithm is then developed with the objective of maintaining low work-in-process inventory and keeping the production close to the demand. The algorithm uses a hierarchical control structure to generate the loading times for each product on each machine in real time and to respond to random disruptions in the system. The system is simulated using this algorithm to study its performance. The performance of the algorithm is also compared to alternative policies.     

鄱阳湖流域水土保持与防洪治涝

鄱阳湖流域水土流失加剧了洪涝灾害。治理水土流失能增强山丘地涵养水源的能力,削洪减沙,减少库容损失,降低河床,具有明显的防洪效益。进行流域防洪规划时,应将防治水土流失与防洪治涝结合起来,因地制宣,综合治理。     

Novel miniature integrated optical goniometers

A new principle and arrangement for directly determining the angle of incidence of an optical beam on an object are proposed and demonstrated. The novelty of the approach lies in the realization of a ‘smart object’, which extracts a portion of the incident beam's power into an optical waveguide attached to the object's surface or embedded in its body for converting the angle of incidence into the position of a guided beam with finite lateral extent. This ‘integrated optical light pointer’ beam is accomplished by means of creating additional degrees of freedom on the target in two different ways. While a first type is based on introducing spatial variations of the waveguide thickness, a second type makes use of a chirp of the grating periodicity. The feasibility for practical applications has been experimentally demonstrated by a direct comparison with a commercial high-resolution encoder, resulting in an r.m.s. error of <30′'. Measurements have been performed for chips fabricated based on replicated polycarbonate substrates and with no external optics, showing the great potential of this approach for realizing low-cost yet high-performance miniature goniometers.