Structural and optical properties of InGaN/GaN triangular-shape quantum wells with different threading dislocation densities

Structural and optical properties of InGaN/GaN multiple triangular quantum well (QW) structures with different threading dislocation (TD) densities of 1.5×108 (sample A) and 4.5×108 cm^-2 (sample B) have been studied. High resolution transmission electron microscopy and x-ray diffraction analysis showed more fluctuation of local In composition in the sample B, which was attributed to the stress field created by the dislocations as it provides a driving force for the migration of In atoms towards dislocations. Severe degradation of photoluminescence intensity of the sample B was also observed at < 50 K. The optical and structural properties of the InGaN/GaN triangular QW structures are overall substantially affected by the TD density. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Physico-chemical, Biochemical and Microbiological Properties of Traditional Polish Pork Fermented Products During Ripening

The physico-chemical and biochemical properties of the raw pork products, spontaneously fermented as entire primal cuts of ham hock (raw smoked ham hock (RSR)) and loin (raw smoked loin (RSL)), were estimated during the 4-week ripening period. A decrease in water content (4 % in RSR and 7 % in RSL) and an increase in protein (2 and 4.5 %, respectively), fat and salt content (1–2 % for both products) were associated with the phenomena of slight drying. An almost 2.5-fold increase of free amino groups dissolved in water, from 480 to 1,100 μMGly/100 g and from 490 to 1,200 μMGly/100 g, accompanied by a gradual increase of total free fatty acids, from 250 to 530 mg/kg and from 270 to 460 mg/kg, was indicated in the RSR and RSL, respectively. The fermentation and accumulation of free fatty acids affected the pH decrease in the RSL, particularly with a low fat content. The increase of tyramine, tryptamine, putrescine and spermine amounts confirm the activity of bacteria strains in the RSR and RSL during ripening. The considerable part of the “house microflora” included the species fermenting in the presence of air or in anaerobic conditions—in the presence of nitrogen. The presence of volatile cell metabolism products (3-hydroxy-2-butanone, 3-methyl-1-butanol and butanoic acid) confirmed a greater amino acid transformation and saccharide fermentation activity of microflora in the RSR. Similarly, products of free fatty acid degradation (pentanal, hexanal and butanoic acid) as well as products of lipid oxidation (e.g. 3-methyl-3-buten-1-ol and 3-methyl-1-butanol) confirmed the far advanced ripening in the RSR with a greater fat content.     

Hyperfine structure measurement of rubidium atom and tunable diode laser stabilization by using Sagnac interferometer

The Rubidium saturated absorption spectra for D2 transition lines are used to measure the Fabry-Perot interferometer free spectral range (FSR). The scale linearity of the laser frequency tuning is determined. The Sagnac interferometer has been used for the laser stabilization. The result shows that the laser frequency is stabilized upto sub-mega Herz level. Also the hyperfine structure [5(2)S(1/2) F = 3 --> F' = 2, 3, 4 5(2)P(3/2) 85Rb] of the rubidium atom has been measured by using the tilt locking method, which shows the same result as the conventional saturation spectroscopy.     

Activation of B-lymphocytes during pollen season. Effect of immunotherapy

BACKGROUND: B-lymphocytes play an important part in the allergic reaction as producers of IgE antibodies. OBJECTIVE: To investigate the cell surface expression of the activation antigens CD23, CD40 and HLA-DR on B-lymphocytes in birch pollen allergic patients before and during birch pollen season and to study the effect of immunotherapy. METHODS: The study included 24 birch pollen allergic patients half of whom were treated with immunotherapy against birch pollen before the start of the season. Eleven of the 24 patients had asthma. Blood samples were taken and lung function was registered before the season began and before the immunotherapy treatment in January to February and during the season in May. The relative number of B-lymphocytes (CD19+) of the lymphocyte population and the cell surface expression of CD23, CD40 and HLA-DR on B-lymphocytes was measured by the use of flow cytometry. RESULTS: In the control group of patients the relative number and concentration of B-lymphocytes, the cell surface expression of CD23, CD40 and HLA-DR on B cells, and the serum concentration of IgE increased during season compared with before season. In contrast, in the immunotherapy treated patients no changes in the number of B cells or cell surface expression of CD23, CD40 and HLA-DR were demonstrated. CONCLUSION: The elevated expression of CD23, CD40 and HLA-DR on B cells, combined with increased levels of IgE in allergic patients during season could be explained by the effect of cytokines produced by activated TH2 cells. A shift from TH2 to TH1 cells might be the mechanism after the absence of signs of B-cell activation in immunotherapy treated patients. The prevention of increased cell surface expression on B cells by immunotherapy may constitute a significant mechanism behind the beneficial effects of immunotherapy in the treatment of pollen atopy.     

Methods for physical impairment constrained routing with selected protection in all-optical networks

In this paper, we investigate the problem of survivable all-optical routing in WDM networks with physical impairments. One of the recent key issues in survivable optical network design refers to maximization of the ratio of routeable demands while keeping the overall network cost low. In WDM networks, this goal can be achieved by routing as many demands in all-optical way as possible. Based on the latest technical trends driven by deployment costs, technical constraints, and backward compatibility, this will not mean that all demands will be routed in all-optical way in the near future. Nowadays, operators are mostly willing to dedicate only a given ratio of their power budget to all-optical routing. This in turn implies a new problem to be solved: operators have to find a way to select demands that should be routed in all-optical way and which should not. The problem gets even more complicated, if we add demand protection issues. In this paper, we introduce and evaluate methods able to maximize the number of demands routed with protection in all-optical way in capacity-constrained networks with limitations on path lengths according to physical impairments.