Pulsed laser irradiation impact on two marine diatoms Skeletonema costatum and Chaetoceros gracilis

The ability of pulsed laser irradiations to cause damage on the biofouling organisms is recently being investigated. If this technique is employed in industries such as power generation wherein a large quantity of water is being used for the cooling purpose, many organisms other than the targeted would get affected. In this study, we have investigated the damage caused by the pulsed laser irradiations from an Nd:YAG laser (fluence 0.1J/cm(2)) for varying durations such as 2, 5, 10, 30, 60 and 300 s on two marine diatom species namely Skeletonema costatum and Chaetoceros gracilis. Upon exposure to low power laser irradiations, these diatom species showed mortalities between 52.6+/-9.3% to 97.7+/-3.1% in the case of S. costatum and 57.8+/-2.5% to 98.9+/-0.6% in the case of C. gracilis for 2 and 300 s of irradiations, respectively. The mortality increased with the increase in the duration of laser irradiation. The estimation of the chlorophyll a concentration in the irradiated samples showed a considerable reduction varying between 9.8% and 57% in C. gracilis and 3% and 70.3% in S. costatum for 2 and 300 s of irradiations, respectively. The laser-survived cells grew as the non-irradiated (control) samples. C. gracilis frustules were broken by the laser whilst, the cell materials were drained out of the frustules in the case of S. costatum. The study therefore showed that the low power pulsed laser irradiations could cause significant damage on the two species of planktonic diatoms.     

Effect of nitrate on corrosion of austenitic stainless steel in boiling nitric acid solution containing chromium ions

The oxidation behavior of chromium and the corrosion behavior of austenitic stainless steel in boiling nitric acid solution containing highly concentrated nitrates were investigated using UV-visible spectroscopic measurements, Raman spectral measurements, immersion tests, and potentiodynamic polarization measurements. The oxidation rate measurement of chromium from Cr(III) to Cr(VI) was performed by 1 M boiling nitric acid solution containing each highly concentrated nitrates: Al(NO₃)₃, Nd(NO₃)₃, Ca(NO₃)₂, Mg(NO₃)₂, and NaNO₃ as a simulant of uranium nitrate in uranium concentrator in reprocessing plants. As a result, the rate of chromium oxidation was different depending on the added nitrates even at the same nitric acid concentration. In addition, the oxidation rate of chromium was increased with increasing the calculated partial pressure of nitric acid in consideration of the hydration of cation of nitrates. Furthermore, the corrosion rate of type 310 stainless steel was accelerated by the solution having a high chromium oxidation rate containing nitrates. These results indicated that the acceleration of the corrosion rate in the solutions depending on the oxidation rate of chromium, and the rate is affected by the salt-effect of nitrates.     

Stability of polydihydrosilane liquid films on solid substrates

The quality of polydihydrosilane liquid films is a key factor in the fabrication of solution-processed silicon films. This study investigates the stability of polydihydrosilane liquid films with a thickness L of ~ 40 nm on solid substrates by a comparison between the observed optical microscope images and the values of the Hamaker constant A_ALS for the air/liquid (polydihydrosilane)/solid substrate systems. A_ALS values for a series of SiO₂-based substrates were determined by adopting a simple spectrum method. We found that the micrographs of the polydihydrosilane films provide direct evidence of stability in accordance with the sign of A_ALS; a stable liquid film with A_ALS > 0 showed a continuous figure, while an unstable film with A_ALS < 0 exhibited an array of dots caused by the rupture of the film. The array of dots in the unstable liquid films has a slight orderly distribution with a period λ that is in accord with the characteristic wavelength of the undulation related to the spinodal-like decomposition in van der Waals unstable liquid.     

Pharmaceutical production of tableting granules in an ultra-small-scale high-shear granulator as a pre-formulation study

Objective: In some of drug developments, the amount of bulk drug powder to use in early stages is limited and it is not easy to supply a sufficient drug amount for conventional preparation methods. Therefore, an ultra-small-scale high-shear granulator (less than 5?g) (USG) was developed and applied to small-scale granulation as a pre-formulation. Method: The sample powder consisted of 66.5% lactose, 28.5% microcrystalline cellulose and 5.0% hydroxypropylcellulose. The granules were obtained to agitate 5?g of the sample powder with 1.0?mL of water at 300?rpm for 5?min after pre-powder mixing for 3?min by the USG and the manual hand (HM) methods. Results: The granules were evaluated by the 10% and 90% accumulated particle size and the recoveries of the granules and the powder solid. Median particle size for the USG and the HM methods was 159.2?±?2.3 and 270.9?±?14.9 μm, respectively. The USG method had a narrower particle size distribution than those by the HM method. The recovery of the granules by USG was significantly larger than that by the HM method. Conclusion: Characteristics of all of the granules indicated that the USG method could produce higher quality granules within a shorter time than the HM methods.     

An optimization approach to establish an appropriate energy group structure for BWR pin-by-pin core analysis

An optimization approach to establish an appropriate multi-group energy structure for boiling water reactor (BWR) pin-by-pin fine mesh core analysis is proposed. In the present approach, the number of energy groups of cross sections is successively reduced or increased. In order to select an energy group boundary that is removed or added, performances of all possible candidates of energy group structures are tested in multi-assembly geometries. Then, the energy group boundary, which provides the minimum difference of the k-infinity or the pin-by-pin fission rate distribution, is finally removed or added. This procedure is repeated until the number of energy groups reaches to the target value. In order to confirm the applicability of the present approach, the accuracies of the k-infinity and the pin-by-pin fission rate distribution are investigated in various 2 × 2 multi-assembly geometries with the established energy group structure. From the verification results, the differences of the k-infinity and the pin-by-pin fission rate distribution between the reference (fine) and the established (coarse) energy group structure are small in the various 2 × 2 multi-assembly geometries. Therefore, we can conclude that the present approach is efficient to establish an appropriate energy group structure for BWR pin-by-pin fine mesh core analysis.     

Model predictive control for line pacing in steel processing

Line pacing control in steel processing lines is known to be a difficult task for operators.?They usually take a conservative control policy in order to avoid shutdown, and the processing capacity of the line has not been fully utilized yet. This paper presents a new modeling and control technique for line pacing based on a hybrid petri net (HPN) and mixed logical dynamical system (MLDS) expressions. The proposed modeling method can harmoniously integrate continuous and discrete aspects of the system. Moreover, the proposed method can provide a suitable formulation for numerical optimization. Based on this hybrid system modeling, the closed‐loop control can be realized by the receding horizon scheme. Numerical examples demonstrate that the processing capacity can be fully utilized by the proposed method. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Testosterone inhibits matrix metalloproteinase-1 production in human endometrial stromal cells in vitro

Androgen receptor (AR) is reported to be expressed in human uterine endometrium, but not much information is available on the role of androgens in human endometrium. The purpose of this study is to investigate the role of androgens in the regulation of matrix metalloproteinase (MMP)-1, which is one of the important MMPs for menstruation and embryo implantation in human endometrium. Human endometrial stromal cells (HESCs) were obtained from human endometrium by enzymatic dissociation method. Purified HESCs were incubated with 17beta-estradiol (E2), testosterone, or E2 + testosterone. Progestins (natural progesterone or medroxyprogesterone acetate) or vehicle (dimethyl sulfoxide) were also added to the media instead of testosterone. Furthermore, hydroxyflutamide (FLU),a specific AR antagonist, was also supplemented to cultured media. The amounts of MMP-1 in cultured media and in HESC lysates were examined by ELISA measurements and western blotting analysis respectively. The expression of ARmRNA in HESCs RNA was analyzed by RT-PCR. Testosterone significantly inhibited MMP-1 in both cultured media and cell lysates in a dose-dependent manner. Progestins also inhibited MMP-1. Furthermore, FLU completely recovered the decrease of MMP-1 induced by testosterone. ARmRNA was detected in all HESCs RNA. The present study demonstrated that the secretion and production of MMP-1 in HESCs in vitro were inhibited by testosterone through androgen receptors in a manner similar to that seen for progesterone. These findings indicate that androgen may play an important role in morphological and functional changes of human endometrium.     

Fabrication of colorless organic materials exhibiting white luminescence using normal and excited-state intramolecular proton transfer processes

Organic, white luminescent materials were fabricated using a mixture of proton-transfer and nonproton-transfer fluorophores. 2'-Methoxy and 2'-hydroxy derivatives of 2-phenylimidazo[1,2-a]pyridine (PIP) have similar UV-absorption properties; however, they exhibit mechanistically different luminescence respectively ascribable to the normal (～420 nm) and excited-state intramolecular proton transfer processes (～530 nm) in the solid state. UV-irradiation of mixed solids excites both components concurrently and results in efficient white luminescence composed of two independent emissions without involving energy transfer process. White luminescent solids are easily transformed into vapor-deposited films under mild conditions, and a colorless and transparent thin film by dissolving in PMMA.