Spectroscopic characterization of naturally and chemically oxidized silicon surfaces

We have determined the thicknesses of naturally and chemically grown oxides on HF-cleaned silicon surfaces in ambient air and in NH4OH/H2O2/H2O solution, respectively, using spectroscopic ellipsometry. The naturally grown oxide thickness versus air-exposure time plots yield a rate constant of 3.5+-0.5 Å/decade in ambient air. Chemical oxidation occurs immediately upon immersing the sample in the chemical solution and leaves the sample surface terminated with ～6 Å of a chemical oxide. Photoreflectance intensity is found to be strongly dependent on such surface processing, and results are explained by the different degree of surface (interface) states

Direct Measurement of Thermal Fluctuation of High-Q Pendulum

We achieved for the first time a direct measurement of the thermal fluctuation of a pendulum in an off-resonant region using a laser interferometric gravitational wave detector. These measurements have been well identified for over one decade by an agreement with a theoretical prediction, which was derived by a fluctuation-dissipation theorem. Thermal fluctuation is dominated by the contribution of resistances in coil-magnet actuator circuits. When we tuned these resistances, the noise spectrum also changed according to a theoretical prediction. The measured thermal noise level corresponds to a high quality factor on the order of 10^5 of the pendulum.Comment: 10 pages, 4 figure

Thermal-noise-limited underground interferometer CLIO

We report on the current status of CLIO (Cryogenic Laser Interferometer Observatory), which is a prototype interferometer for LCGT (Large Scale Cryogenic Gravitational-Wave Telescope). LCGT is a Japanese next-generation interferometric gravitational wave detector featuring the use of cryogenic mirrors and a quiet underground site. The main purpose of CLIO is to demonstrate a reduction of the mirror thermal noise by cooling the sapphire mirrors. CLIO is located in an underground site of the Kamioka mine, 1000 m deep from the mountain top, to verify its advantages. After a few years of commissioning work, we have achieved a thermal-noise-limited sensitivity at room temperature. One of the main results of noise hunting was the elimination of thermal noise caused by a conductive coil-holder coupled with a pendulum through magnets.Comment: 10 pages, 6 figures, Proceedings of the 8th Edoardo Amaldi Conference on Gravitational Wave

Biological Differences Between Ovarian Cancer-associated Fibroblasts and Contralateral Normal Ovary-derived Mesenchymal Stem Cells

Background/Aim: The aim of this study was to clarify the biological differences between ovarian cancerassociated fibroblasts (OCa-CAFs) and normal ovary-derived mesenchymal stem cells (NO-MSCs). Materials and Methods: Surgically resected ovarian cancer and contralateral normal ovarian tissue samples were cut into small pieces for culture as “explants”. The number of outgrown cells, their proliferative kinetics, and expression levels of cell surface markers of CAFs, as well as three miRNAs in OCa-CAFs and NO-MSCs were compared directly. Differentially expressed genes between both groups were also investigated. Results: Comparable numbers of outgrown cells were harvested from both groups. Significantly higher expression of α-smooth muscle actin and miR-142 was found in OCa-CAFs, which decreased significantly during ex vivo cell expansion. A total of 21 differentially expressed genes were identified between both groups. Conclusion: OCa-CAFs showed different biological properties in direct comparison with NO-MSCs, which might play major roles in the pathogenesis of ovarian cancer

Cryogenic measurement of the optical absorption coefficient in sapphire crystals at 1.064(micro)m for the Large-scale Cryogenic Gravitational wave Telescope

We have applied laser calorimetry to the measurement of optical absorption in mono-crystalline sapphire at cryogenic temperatures. Sapphire is a promising candidate for the mirror substrates of the Large-scale Cryogenic Gravitational wave Telescope. The optical absorption coefficients of different sapphire samples at a wavelength of 1.064(micro)m at 5K were found to average 90ppm/cm.Comment: 8 pages, accepted to Phys. Lett.

Unjuk Kerja Down-Flow Hanging Sponge (DHS) Bioreaktor sebagai Secondary Treatment untuk Pengolahan Limbah Domestik

Wastewater pollution will continue to grow as the population and community activities continue to increase. Various techniques have been applied for domestic waste treatment, but generally these processes require relatively high operation and maintenance costs. Down Flow Hanging Sponge (DHS) has been proposed as a solution to the problem of handling domestic waste for developing countries. DHS bioreactor is a biological waste treatment that does not require an aerator and is easy to operate. This study aims to evaluate DHS bioreactors that can be applied in Indonesia. DHS bioreactor is operated with 4 hours hydraulic retention time (HRT). The results showed that DHS bioreactor is able to reduce up to 34% Chemical Oxygen Demand (COD) total, 33% soluble Chemical Oxygen Demand (COD), 80% Biological Oxygen Demand (BOD) total, and 65% Ammonia.ABSTRAK Pencemaran  air limbah akan terus bertambah dengan meningkatnya jumlah penduduk dan aktifitas masyarakat. Berbagai proses telah diaplikasikan untuk pengolahan limbah domestik, tetapi umumnya proses-proses tersebut membutuhkan biaya operasi dan perawatan yang relatif mahal. Downflow Hanging Sponge (DHS) telah diusulkan sebagai pemecahan persoalan penanganan limbah domestik untuk negara-negara berkembang. DHS bioreaktor adalah pengolahan limbah secara biologis yang  tidak membutuhkan aerator dan mudah dalam pengoperasian. Penelitian ini bertujuan untuk mengevaluasi bioreaktor DHS sehingga dapat diterapkan di Indonesia. Bioreakor DHS dioperasikan dengan hydraulic retention time (HRT) 4 jam. Hasil penelitian menunjukkan DHS bioreaktor mampu mengurangi  hingga 34% Chemical Oxygen Demand (COD) total, 33% soluble Chemical Oxygen Demand (COD), 80% Biological Oxygen Demand (BOD) total, dan 65%  ammonia

Conduction Effect of Thermal Radiation in a Metal Shield Pipe in a Cryostat for a Cryogenic Interferometric Gravitational Wave Detector

A large heat load caused by thermal radiation through a metal shield pipe was observed in a cooling test of a cryostat for a prototype of a cryogenic interferometric gravitational wave detector. The heat load was approximately 1000 times larger than the value calculated by the Stefan-Boltzmann law. We studied this phenomenon by simulation and experiment and found that it was caused by the conduction of thermal radiation in a metal shield pipe.Comment: 7 pages, 4 figures, 2 tables, Submitted to Jpn. J. Appl. Phy

Measurement of the mechanical loss of a cooled reflective coating for gravitational wave detection

We have measured the mechanical loss of a dielectric multilayer reflective coating (ion-beam sputtered SiO$_2$ and Ta$_2$O$_5$) in cooled mirrors. The loss was nearly independent of the temperature (4 K $\sim$ 300 K), frequency, optical loss, and stress caused by the coating, and the details of the manufacturing processes. The loss angle was $(4 \sim 6) \times 10^{-4}$. The temperature independence of this loss implies that the amplitude of the coating thermal noise, which is a severe limit in any precise measurement, is proportional to the square root of the temperature. Sapphire mirrors at 20 K satisfy the requirement concerning the thermal noise of even future interferometric gravitational wave detector projects on the ground, for example, LCGT.Comment: 8 pages, 6 figures, 3 tables : accepted version (by Physical Review D

Current status of Japanese detectors

Current status of TAMA and CLIO detectors in Japan is reported in this article. These two interferometric gravitational-wave detectors are being developed for the large cryogenic gravitational wave telescope (LCGT) which is a future plan for detecting gravitational wave signals at least once per year. TAMA300 is being upgraded to improve the sensitivity in low frequency region after the last observation experiment in 2004. To reduce the seismic noises, we are installing new seismic isolation system, which is called TAMA Seismic Attenuation System, for the four test masses. We confirmed stable mass locks of a cavity and improvements of length and angular fluctuations by using two SASs. We are currently optimizing the performance of the third and fourth SASs. We continue TAMA300 operation and R&D studies for LCGT. Next data taking in the summer of 2007 is planned. CLIO is a 100-m baseline length prototype detector for LCGT to investigate interferometer performance in cryogenic condition. The key features of CLIO are that it locates Kamioka underground site for low seismic noise level, and adopts cryogenic Sapphire mirrors for low thermal noise level. The first operation of the cryogenic interferometer was successfully demonstrated in February of 2006. Current sensitivity at room temperature is close to the target sensitivity within a factor of 4. Several observation experiments at room temperature have been done. Once the displacement noise reaches at thermal noise level of room temperature, its improvement by cooling test mass mirrors should be demonstrated.Comment: 6 pages, 5 figures, Proceedings of GWDAW-1

Application of sapphire bonding for suspension of cryogenic mirrors

In order to design a suspension for large cryogenic mirror, we have measured thermal conductance and shear strength of sapphire bonding in comparison with direct bonding and hydroxide-catalysis bonding. Thermal conductance per unit area of 4 [W/K/mm2] for the direct bonding and 0.3 [W/K/mm2] for the hydroxide-catalysis bonding were obtained around 20K. Shear strength of 28[MPa] for the direct bonding and 6.5 [MPa] for the hydroxide-catalysis bonding were measured at 300K. Based on those values, an estimated area that support a weight of a mirror produces a temperature step of less than 1% of a difference of temperature in between the main mirror and a mirror of Suspension Point Interferometer