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The reaction of Al and H2O is a promising method for the renewable production of H2 (an environmentally friendly fuel whose combustion produces only water), because it does not directly include fossil fuels conversion. This reaction was studied at extreme pH values as low as 1 and as high as 13.5 with HCl, H2SO4, and NaOH, and at low hydrothermal temperatures of 40-100 °C. Factors such as pH, temperature, and solution medium influenced H2 production, which was considerably greater at higher temperatures and more extreme pH (acidic or alkaline). Alkaline conditions consistently favored more rapid H2 production than acidic conditions. Under the most extreme conditions, the activation energy was ∼60 kJ mol−1 for both acidic and alkaline reactions. A model predicting H2 production in acidic reactions was derived from the reaction mechanism and kinetics. The model yielded a good fit to on-site measurements at the Tamagawa and Zao hot springs in northeast Japan. This study would aid the development of industrial H2 production systems using natural acidic hot springs or alkaline industrial wastewater.

Hydrogen is gaining attention as an energy source, but its production through fossil-fuel use is not environmentally friendly. A more sustainable source could be the hydrothermal reaction involving aluminum and water reaction, which owns technical issues on aluminum passivation and material sources for the upscale application. This study analyzes the aluminum-water hydrothermal reaction at laboratory and field scales and includes an environmental assessment of H2 fuel production involving hot-spring water with extremely low pH (~1) and boiling temperature (~373 K). Acidic hot-spring alternates water sources, and its unique feature activates aluminum surface by attacking oxide layer, hence enables H2 generation. Aluminum waste sources include dross and cutting chips, which could replace primary aluminum metal. The highest H2 yield could be obtained of about ~55 mmol H2 gAl−1 for the chip (almost reached theoretical yield) and a smaller amount of ~20 mmol H2 gAl−1 for dross. The environmental assessment comprises carbon dioxide emissions and energy consumption from the overall H2 fuel system resulting in a reduced environmental impact. The proposed hydrogen production method encourages hydrogen energy development from the local scale. In addition, the use of aluminum waste materials is a new and useful waste management strategy than direct disposal, and hot-springs use advances its direct utilization.

Spectroscopic characteristics of critical phenomena of multicomponent geofluids and seawater were observed by using autoclave with transparent windows (visible-type autoclave). First, pure H2O fluids were observed by spectroscopic measurements at 500–800nm under high temperature and pressure conditions. The intensity of light transmitted decreased significantly as the critical point of H2O fluid was approached, and the local minimum intensity of transmitted light corresponded to the critical temperature and pressure of all fluids tested. The experimentally determined critical temperature and pressure of H2O were similar to the results of previous work. Critical temperatures and pressures of multicomponent geofluids and seawaters were determined. Spectroscopic measurement could provide information of molecular behaviours of aqueous fluid involving several kinds of electrolytes.

Hydrothermal activity in the crust results in the precipitation of large volumes of silica and often involves the formation of ore deposits, the shaping of geothermal systems, and recurring earthquakes. Pore fluid pressures fluctuate between lithostatic and hydrostatic, depending on seismic activity, and some models suggest the possibility of flash vaporization, given that fluid pressures can drop to the level of vapour at fault jogs during seismic slip. The phase changes of water could create extremely high supersaturations of silica, but the mechanisms of quartz vein formation under such extreme conditions remain unclear. Here we describe flash experiments conducted with silica-saturated solutions under conditions ranging from subcritical to supercritical. We found that amorphous silica is produced instantaneously as spherical nano- to micron-scale particles via nucleation and aggregation during the evaporation of water droplets. The nanoparticles are transformed to microcrystalline quartz very rapidly by dissolution and precipitation in hydrothermal solutions, with this process requiring less than one day under supercritical conditions because of the huge surface areas involved. We suggest that such short-lived silica nanoparticles have significant impacts on the dynamic changes in mechanical behaviour and hydrology of hydrothermal systems in volcanic areas.

Serpentinization occurs via interactions between mantle peridotite and water that commonly passes through the crust. Given that such a fluid has a high silica activity compared with mantle peridotite, it is thought that serpentinization and silica metasomatism occur simultaneously at the crust–mantle boundary. In this study, we conducted hydrothermal experiments in the olivine (Ol)–quartz (Qtz)–H 2 O system at 250 °C and vapor-saturated pressure under highly alkaline conditions (NaOH aq , pH = 13.8 at 25 °C) to clarify the mechanism of silica metasomatism at the crust–mantle boundary. Composite powders consisting of a Qtz layer and an Ol layer were set in tube-in-tube vessels. After the experiments, the extents of serpentinization and metasomatic reactions were evaluated as a function of distance from the Ol–Qtz boundary. The mineralogy of the reaction products in the Ol-hosted region changed with increasing distance from the Ol–Qtz boundary, from smectite + serpentine (Smc zone) to serpentine + brucite + magnetite (Brc zone). Olivine hydration proceeded in both zones, but the total H 2 O content in the products was greater in the Brc zone than in the Smc zone. Mass balance calculations revealed that olivine hydration occurred without any supply of silica in the brucite zone. In contrast, the Smc zone was formed by silica metasomatism via competitive hydration and dehydration reactions. In the Smc zone, smectite formed via the simultaneous progress of olivine hydration and serpentine dehydration, and around the boundary of the Smc and Brc zones, serpentine formation occurred by olivine hydration and brucite dehydration. The relative extent of hydration and dehydration reactions controlled the along-tube variation in the rate of H 2 O production/consumption and the rate of volume increase. Our findings suggest that the competitive progress of serpentinization and silica metasomatic reactions would cause fluctuations in pore fluid pressure, possibly affecting the mechanical behavior of the crust–mantle boundary.

The present study evaluates aperture distributions and fluid flow characteristics for variously sized laboratory-scale granite fractures under confining stress. As a significant result of the laboratory investigation, the contact area in fracture plane was found to be virtually independent of scale. By combining this characteristic with the self-affine fractal nature of fracture surfaces, a novel method for predicting fracture aperture distributions beyond laboratory scale is developed. Validity of this method is revealed through reproduction of the results of laboratory investigation and the maximum aperture-fracture length relations, which are reported in the literature, for natural fractures. The present study finally predicts conceivable scale dependencies of fluid flows through joints (fractures without shear displacement) and faults (fractures with shear displacement). Both joint and fault aperture distributions are characterized by a scale-independent contact area, a scale-dependent geometric mean, and a scale-independent geometric standard deviation of aperture. The contact areas for joints and faults are approximately 60% and 40%. Changes in the geometric means of joint and fault apertures (µm), em, joint and em, fault, with fracture length (m), l, are approximated by em, joint = 1 × 102 l0.1 and em, fault = 1 × 103 l0.7, whereas the geometric standard deviations of both joint and fault apertures are approximately 3. Fluid flows through both joints and faults are characterized by formations of preferential flow paths (i.e., channeling flows) with scale-independent flow areas of approximately 10%, whereas the joint and fault permeabilities (m2), kjoint and kfault, are scale dependent and are approximated as kjoint = 1 × 10−12 l0.2 and kfault = 1 × 10−8 l1.1.

Silica activity is one of the key factors in controlling reaction paths of serpentinization. We conducted hydrothermal experiments in the olivine (Ol)–orthopyroxene (Opx)–H 2 O system at 250 °C and at a vapor-saturated pressure of 3.98 MPa to explore the role of silica diffusion in aqueous fluids during serpentinization. Olivine (Fo 91 ), orthopyroxene (En 91 ), or their composite powders (with Ol/Opx/Ol zones) were set in tube-in-tube vessels, and solution chemistry and the extent of serpentinization were analyzed in detail. In the Ol–H 2 O experiments, the product changed from serpentine + magnetite to serpentine + brucite + magnetite, accompanied by a Si-drop in the solutions. Serpentinization proceeded uniformly throughout the reaction tube, indicating that the supply of water was not the rate-determining process. In the Opx–H 2 O experiments, orthopyroxenes were dissolved along the cleavages, and the amount of newly formed serpentine was very small. The silica activity of the solutions in the Opx–H 2 O experiments was 1–3 orders higher than in the Ol–H 2 O experiments. In the Ol–Opx–H 2 O experiments, serpentinization proceeded in both the Ol and Opx zones. In the Opx zone, the extent of serpentinization was constant, whereas in the Ol zone, serpentinization was most extensive along the boundary between the Ol and Opx zones, and it decreased gradually away from the boundary. Serpentinization in the Ol–Opx–H 2 O experiments was modeled simply by coupled processes involving silica diffusion and two serpentinization reactions: a silica-consuming reaction after olivine and a silica-releasing reaction after orthopyroxene. The spatial pattern of the extent of serpentinization was controlled by the diffusion coefficient of silica in aqueous solution, D SiO2,aq , and the apparent reaction rate constants k ′ Ol in the olivine zone, and k ′ Opx in the orthopyroxene zone. Assuming D SiO2,aq = 2.0 × 10 −4 cm 2 /s, the observed variation in the extent of serpentinization after a run of 1512 h is best fitted by simulation with k ′ Ol = 4.4 × 10 −4 and k ′ Opx = 3.2 × 10 −5 s −1 , indicating a reaction rate constant ∼14 times higher in the Ol zone than in the Opx zone. Our experimental results represent an analogue of serpentinization in natural hydrothermal systems with a high porosity, and we suggest that the spatial variation of serpentine as a function of the distance from a source of silica could be a useful indicator of the relative magnitudes of reaction, mass transport, fluid flow as well as temperature during hydrothermal alteration of oceanic lithosphere.

Silica activity plays an important role in controlling reaction paths and rates of serpentinization in the oceanic lithosphere. In this study, we conducted hydrothermal experiments on serpentinization in the olivine (Ol)- orthopyroxene (Opx)-H2O system at 250 °C and vapor-saturated pressure (3.98 MPa). We used a tube-in-tube vessel with powders of Ol/Opx/Ol zones, and the extents of serpentinization and solution chemistry were analyzed in detail. The run time was up to 1512 hours. The silica activity of the solutions decreased with time from 0.144 to 0.005 mmol/kg, whereas the Mg concentration and pH were nearly constant. The experimental products were serpentine (mainly lizardite) ± magnetite, and neither talc nor brucite was found. The extent of serpentinization, measured by thermogravimetry and SEM-images, revealed that serpentinization was most extensive along the boundary between the Ol and Opx zones, and decreased gradually away from the boundary. This extent of serpentinization pattern is explained by the coupled processes of silica diffusion and surface reactions in both zones (silica-consuming reaction in the Ol zone and silica- releasing reaction in the Opx zone).

The structure of water under high temperature–pressure conditions in mesospace was investigated by measuring the infrared spectra of water in mesoporous silica. Absorption peaks attributed to OH-stretching vibration of water in mesoporous silica were detected at lower wavenumbers as compared with bulk water, and the absorption peak positions were dependent on pore diameter. For small pore diameters (3–20 nm), absorption peak positions of water were detected at lower wavenumbers (ca. 3,300 cm−1) at 400 °C, while for larger pore diameters (30–50 nm) the peaks were detected at higher wavenumbers (ca. 3,500 cm−1). We attribute these features to the effects of mesoporous silica surface structure on the structural and vibrational modes of water. Furthermore, absorption peak positions changed significantly at different pore sizes (20 and 30 nm), indicating that the structure of water in small pores approaches a more ice-like structure. Based on our experimental results, the structured water layer in mesoporous silica is estimated to be at least 10 nm thick, which is thicker than that previously documented in molecular dynamic simulation studies where the thickness of structured water was found to be two or three layers from the surface.

The X-ray CT based numerical analysis of fracture flow for core samples, recently developed by the authors, was applied to two granite core samples having either a mated artificial or a mated natural fracture at confining pressures of 5 to 50 MPa. A third-generation medical X-ray CT scanner was used to image the samples within a core holder consisting of an aluminum liner and a carbon fiber overwrap. Fracture models (i.e., aperture distributions) were obtained by the CT images, the resolution of which was coarser than the apertures, and a single-phase flow simulation was performed using a local cubic law-based fracture flow model. Numerical results were evaluated by a fracture porosity measurement and a solution displacement experiment using NaCl and NaI aqueous solutions. These numerical results coincided only qualitatively with the experimental results, primarily due to image noise from the aluminum liner of the core holder. Nevertheless, the numerical results revealed flow paths within the fractures and their changes with confining pressure, whereas the experimental results did not provide such results. Different stress-dependencies in the flow paths were observed between the two samples despite the similar stress-dependency in fracture porosity and permeability. The changes in total area of the flow paths with confining pressure coincided qualitatively with changes in breakthrough points in the solution displacement experiment. Although the data is limited, the results of the present study suggest the importance of analyzing fluid flows within naturally fractured core samples under in situ conditions in order to better understand the fracture flow characteristics in a specific field. As demonstrated herein, X-ray CT-based numerical analysis is effective for addressing this concern. Using a multi-phase flow model, as well as a core holder constructed of an engineered plastic, should provide a useful, non-destructive, and non-contaminative X-ray CT-based fracture flow analysis for core samples under in situ conditions in future studies.

Hydrogen production from water with S2− as a reductant under hydrothermal conditions is an effective new method, in which S2− is oxidized into S2O32−, SO32− and SO42−. However, the reactor wall had great effect on hydrogen production as large amount hydrogen is produced with Hastelloy C-22 reactor while almost no hydrogen generated in SUS 316 reactor. Therefore, the influence of main components of Hastelloy C-22 reactor (Co/W/Ni) and SUS 316 reactor (Fe) on hydrogen production with H2S as the reductant was investigated. The results showed that Fe had negative effect, whereas W, Co and Ni had significant positive effect on improving hydrogen production. These results provided a possible explanation for no hydrogen generated with SUS 316 reactor，and some suggestions for improving hydrogen production. The highest hydrogen production of 199 mL (2 times than the control) was obtained with 4.00 mmol Co, 4.00 mmol W, and 1.00 mmol Ni.

Summary The present study focuses on the feasibility of a precise 3D numerical modeling coupled with X-ray computed tomography (CT), which enables simple analysis of heterogeneous fracture flows within reservoir core samples, as well as the measurement of porosity and permeability. A numerical modeling was developed and applied to two fractured granite core samples. One of the samples had an artificial single fracture (sample dimensions: 100 mm in diameter, 150 mm in length), and the other had natural multiple fractures (sample dimensions: 100 mm in diameter, 120 mm in length). A linear relationship between the CT value and the fracture aperture (fracture-aperture calibration curve) was obtained by X-ray CT scanning for a fracture-aperture calibration standard while varying the aperture from 0.1 to 0.5 mm. With the fracture-aperture calibration curve, 3D distributions of the CT value for the samples (voxel dimensions: 0.35×0.35×0.50 mm3) were converted into fracture-aperture distributions in order to obtain fracture models for these samples. The numerical porosities reproduced the experimental porosities within factors of approximately 1.3 and 1.1 for the single fracture and the multiple fractures, respectively. Using the fracture models, a single-phase flow simulation was also performed with a local cubic law-based fracture-flow model for steady-state laminar flow of a viscous and incompressible fluid. The numerically obtained permeabilities were larger than the experimentally obtained permeabilities by factors of approximately 2.2 and 2.7 for the single fracture and the multiple fractures, respectively. However, these discrepancies can be reduced to approximately 1.3—2.1 and 1.6-2.6, respectively, by simply using the correction factor for the cubic-law equation proposed by Witherspoon et al. (1980). Consequently, a precise numerical modeling coupled with X-ray CT is essentially feasible. Furthermore, the development of preferential flow paths (i.e., channeling flow) was clearly demonstrated for multiple fractures, which is much more challenging to achieve by most other methods. Further progress in modeling should enable the in-situ evaluation of heterogeneous fracture flow within reservoir core samples, as well as the clarification of the impacts of the heterogeneity on the productivity of wells and, for example, the efficiency of recovery by water-/gasflooding.

We conducted hydrothermal flow-through experiments at 430 °C and 31 MPa to investigate the mechanism of silica precipitation on granite under crustal conditions. Two experiments were performed using different input solutions: a single-component Si solution, and a multi-component solution with minor Al, Na, and K. The degree of supersaturation with respect to quartz, Ω = CSi/CSi,Qtz,eq, where CSi and CSi,Qtz,eq indicate Si concentration in solutions and the solubility of quartz within water, respectively, decreased from 3–3.5 to

Direct measurement of a contact area using pressure-sensitive film was performed for artificially generated granite tensile fractures, with different shear displacements of 2, 3, and 5 mm and at various normal stresses of up to approximately 100 MPa, to clarify the relationship between anisotropic flow and normal stress in a rock fracture with shear displacement. Aperture distributions with contact areas were then numerically generated using fracture surface geometry data, and anisotropic flow was evaluated through a bi-directional flow simulation. The directional distributions of contacting asperities in the fracture plane were clearly observed for every given condition and the contacting asperities tended to align in the direction perpendicular to shear displacement. Generally, the contact area increased and the anisotropic distribution was enhanced with increasing normal stress. However, the contact areas for ≥ 3 mm shear displacement were less stress dependent. Anisotropic flow with higher permeability in the perpendicular direction was always observed for aperture distributions with an anisotropic distribution of the contacting asperities. Flow paths created in the aperture distributions seemed less tortuous in the perpendicular direction due to the distribution of the contacting asperities. The anisotropic flow was enhanced with increasing normal stress to the fracture, and was more evident for the smaller shear displacements of 2 mm due to the high sensitivity of the contact area to the normal stress. The results suggested that the anisotropic flow was likely for a wide range of normal stresses (and correspondingly, at varying depths in the Earth's crust), at which anisotropic flow was enhanced with increasing normal stress based on the stress dependence of the contact area. In addition, the stress dependent anisotropic flow is expected for much higher normal stresses because complete fracture closure with 100% contact area may be unexpected under the crustal stress conditions at depths of several to ten thousand meters.

Hydrothermal experiments of dissolution of granite and quartz with pure water up to 600°C and 60 MPa were carried out in order to evaluate chemical reaction under sub- and supercritical conditions. The supercritical region beyond the critical point for water has been inferred to be a homogeneous state, which does not correspond to either a true liquid phase, or a true vapor phase. Results of dissolution experiments of granite and quartz in a supercritical state (artificially defined as higher pressures and temperatures than the critical point), show this fluid can be subdivided into two apparent phases comprising a ‘liquid-like’ region and a ‘vapor-like’ region. Chemical phenomena with respect to dissolution reactions in the ‘liquid-like’ region are more similar to those of subcritical water, whilst those reactions in the ‘vapor-like’ region even in the supercritical state are considered to be weak. The critical point of various kinds of geofluids, composed of solutions in the H2O-CO2-NaCl system was experimentally determined using a visible type autoclave. Chemical reaction diversity, depending on location of the critical point for a given solution and apparent phase boundary in terms of chemical reaction within the supercritical state, was recognized by hydrothermal experiments.

Changes in systemic arterial blood pressure and the degree of cerebral vasospasm were investigated in 125 patients with aneurysmal subarachnoid hemorrhage.Systemic arterial blood pressure was measured every 2 hours in each patient for a period of more than 2 weeks, and a fall in systemic blood pressure (FBP) was defined as a decrease of40 mmHg of systolic blood pressure between two consecutive measurements.A total of 91 FBPs occurred in 52 (41.6%) of 125 patients despite specific post-operative management to prevent hypovolemia. Five (5.5%) of the 91 FBPs occurred just before the onset of symptomatic vasospasm. Symptomatic vasospasm was observed in 36 (69.2%) of 52 patients with FBP and in 32 (43.8%) of 73 patients without FBP (p0.01, chi-squared test). A hypodense area on computed tomographic scans in association with cerebral vasospasm was observed in 25 (48.1%) of 52 patients with FBP and in 21 (28.8%) of 73 patients without FBP (p0.05).We conclude that FBP might result from delayed cerebral vasospasm and/or brain dysfunction owing to subarachnoid hemorrhage itself.

Flow-through experiments were performed for single tensile fractures artificially created in granite, using Rubber-Confining Pressure Vessel (R-CPV), which has been developed for the experiments under relative high confining pressure conditions up to 100 MPa. The experimental results showed great differences in permeability depending on degree of offset along the fracture surface. In case of the fractures without offset, permeability decreased significantly with increasing confining pressure until around 40-50 MPa, beyond which the permeability, however, decreased gradually and then became constant, and remained much higher than that of rock matrix even at 100 MPa. In case of the fractures with 1, 3, 5 and 10 mm offset, permeability was much higher than that of the fractures without offset. The behavior of permeability for increase of confining pressure, however, drastically changed between 1 mm and other offset conditions. No obvious decrease of permeability was observed with increasing confining pressure in case of 3, 5 and 10 mm offset, while permeability decreased continuously until 70 MPa and abrupt decrease was also observed at 80 MPa in case of 1 mm offset. Those results indicate understanding of offset conditions is a key factor for prediction of productivity in oil/gas fractured reservoir.

Calvarial defects sometimes require cranioplasty to protect the brain. Alloplastic materials, such as acrylic resin, hydroxyapatite ceramics, and titanium, involve various problems, such as vulnerability, infection, deformity resulting from growth, and high cost. We devised a new bone transport model in the rabbit based on the distraction osteogenesis theory of Ilizarov. Twelve Japan white rabbits with a mean body weight of 2.5 kg aged 12 weeks were used. Craniectomy (7 x 14 mm) was performed in 12 rabbits. Trapezoid bone osteotomy was performed anterior to the calvarial defect in 10 rabbits. The distraction device (Extension-plates) was fixed between the trapezoid bone island and the skull. Distraction was initiated 5 days postoperatively. The device was activated once every other day, with approximately 0.75 mm or 0.5 mm per activation. Bone distraction was continued until the rod could not be moved. The lengths of distraction were 4 mm in two cases, 5 mm in one case, 6 mm in one case, and 7 mm in two cases, with a mean of 5.5 +/- 0.56 mm. Both radiographic and histological findings showed osteogenesis by intramembranous ossification and trans-chondroid bone formation. Distraction osteogenesis has potential clinical applications in cranioplasty, especially in children because usage of autogenous bone is difficult if not impossible in most cases.

High temperature-pressure cell for micro-IR and Raman spectroscopy have been developed to investigate molecular structure of water under sub- and supercritical conditions. The maximum temperature and pressure of the cell were 400 °C and 50 MPa, and artificial yellow diamond was installed as a transparent window of the cell. In case of micro-IR spectroscopic measurement, incident beam was illuminated to the high temperature-pressure cell using the Cassegrainian mirror, and reflected light was analyzed by FTIR system. In case of micro-Raman spectroscopic measurement, an incident laser beam (Nd:YAG laser: 532 nm) was irradiated into the cell through standard optical lens. As a result of infrared spectroscopic measurements of water, the broad peak around 3360 cm-1 of infrared spectra, attributed to OH stretching vibration mode of water molecular, was observed at room temperature and pressure. The peak position shifted to higher wavenumber with increasing temperature and shifted to lower wavenumber with increasing pressure. Continuous shift of the OH stretching vibration mode of water molecule was detected by using newly designed high temperature-pressure cell. The peak position and behavior of peak shift of interfacial water were affected by substrate. In case of interfacial water on artificial quartz, the peak position shifted to higher wavenumber with increasing temperature, however no obvious change was observed with as a function of pressure. It was possible to measure IR and Raman spectra under supercritical condition by using high temperature-pressure cell, and characteristics of molecular structure of interfacial water revealed by IR spectra was changed by environmental conditions such as temperature, pressure and substrate.

We report on an evidence of anisotropy in flow path in a single fracture on the basis of measurements of a contact area in a fracture with shear offset of up to 5 mm undergoing normal stress of up to 90 MPa. An area of contact in a fracture undergoing normal stress is measured by using a pressure‐sensitive sheet inserted between fracture surfaces. This method allows simple measurements of contact area in the stressed conditions. Our results show that contact area increases with an increase in normal stress, on the contrary, contact area decreases with an increase in the offset. These dependencies in a contact area suggests that an open area, i.e., aperture area, which is illustrated as an area except for contact area in a fracture, can change associated with normal stress even under the condition of 100 MPa. In addition, we observed that contact area distributes in the direction perpendicular to the direction of offset, which indicates an anisotropy in aperture distribution that become possible flow path in a fracture. Results of numerical simulation of fluid flow in a fracture support the anisotropy in aperture distribution and consequent anisotropy in fluid flow in a fracture. The anisotropy in aperture distribution suggests an anisotropy in fracture permeability since tortuousity in a flow path could be affected by the aperture distribution.

A new type of confining vessel has been developed to undertake high-pressure, flow test experiments, at simulated lithospheric stress conditions. Confining pressure is generated by the uniaxial compression of a rubber medium, which leads to the term Rubber-Confining Pressure vessel ‰ (R-CPV) to describe this system. The pressure vessel is composed of an outside cylinder, an inside cylinder to hold the sample, rubber to generate the confining pressure and facilitate sample sealing, a hollow piston for rubber compression, and an outside piston for hollow piston compression and maintaining inner fluid pressure. The fundamental principle of the R-CPV apparatus is the establishment of confining pressures which utilizes rubber elasticity to generate isotropic pressure. The rubber is bound to the sample and hollow piston only compresses the rubber. Pressure of compression is converted to confining pressure, which correspondingly affects the sample. The outside piston has holes for fluid inflow and outflow. Testing of the R-CPV vessel, using butadiene rubber, has shown it can generate over 100 MPa maximum confining pressure, with 245kN pressing capacity, and facilitate permeability measurements under a range of high confining pressures. For example, preliminary results of flow test experiments for tension cracks in Inada granite, show hydraulic permeability rapidly decreases at 50 MPa. Our experiments show that the new R-CPV apparatus has great potential for better understanding a wide range of geological issues, and likely industrial applications, as it can accommodate permeability-flow testing under a wide range of high confining pressure conditions.

Viscosity changes of hectorite slurry and drilling mud water under hydrothermal condition were observed by using stirring autoclave coupled with torque meter. Semi-quantitative values of viscosity were estimated on the basis of an empirical liner function between share rate and torque of a standard fluid. Viscosity of the drilling mud water changed slightly in the range from room temperature to 220 °C, suggesting moderate characteristics for high temperature mud water. But its viscosity depleted suddenly above 220 °C, which indicates that two phase separation was occured due to alteration of the mud water. Viscosity of the hectorite slurry increased in the ranging from 120 °C to 180 °C, which corresponds to the crystallization temperature of hectorite. However, its viscosity decreased above 180 °C after crystallization of hectorite. These facts indicate that two phase separation, composing from crystallized hectorite and residual solution, was occurred in the temperature range up to 180°C. Hectorite slurry is one of possible agents for plugging fractures in geothermal reservoir to prevent lost circulation. The equipment developed here and estimation method of viscosity are applicable to evaluate plugging process of hectorite slurry in a geothermal reservoir.

Quantification theory type II was used to predict the outcome of 63 patients with head injury. Age, sex, two factors based on neurological examination, and seven factors based on findings of skull radiography and computed tomography of the head were selected as predictors. Patient outcome was evaluated 6 months after injury and assigned to good recovery, severe disability, or death. Discriminant analysis of patient outcomes was performed using the 11 factors. Two category scores were obtained for each category, since the highest correlation ratios were 0.869 and 0.252, and others were less than 10-15. For each patient, a pair of sample scores was then obtained by simple summation of the 11 category scores. Pairs of sample scores were plotted, and the three groups of patient outcomes were clearly distinguishable without exception. These findings show that the outcome of patients with head injury can be accurately discriminated by quantitative analysis of qualitative data.

Li-bearing tosudite has a regularly interstratified structure consisting of chlorite and smectite layers. Hydrothermal treatment of unground and ground Li-tosudite was carried out under 150°C to 250°C in a distilled water and various concentrations of NaOH solutions, and the reacted products were examined by XRD, ethylene gricol treatment and methylene blue absorption capacity.The final reacted products obtained from the both of unground and ground Li-tosudite were mainly analcime, and swelled Li-tosudite was also formed as a by-product. The formation temperature of analcime using ground Li-tosudite was low compared with that using unground Li-tosudite, and its temperature was also related to concentration of NaOH solution. The analcime formation temperature become low with increasing NaOH concentration in the both cases of unground and ground Li-tosudite.Heterogeneous substitution of interlayer cation (Na+) was considered to be occurred on the basis of different features of XRD profile after ethylene gricol treatment and under various relative humidity states.The interlayer structure of Li-tosudite was altered into complex interlayer structure of swelled Li-tosudite, and analcime was readily obtained as a final product from the unground Li-tosudite compared with the ground Li-tosudite. These facts suggest that the reacted products of hydrothermal treatment reflect an original crystal structure of the starting material.

Hectorite is a smectite clay having an ideal composition of Na0.33 (Mg2.67Li0.33) Si4O10 (OH) 2·nH2O, which has been used as an effective colloidal dispersion system due to its favorable rheological properties.When amorphous slurry comprising approximately 2-5 weight % of hectorite composition, which is prepared from sulfuric-acid solved water glass mixed with aqueous solutions of MgC12, LiOH and NaOH, is hydrothermally treated at 150-350°C conditions for 1-2 hour, viscous hectorite gel is formed above 200°C: the process may be applicable to water control of flowing and/or plugging in the geothermal reservoir fractures. Laboratory test for a water control system has been carried out using a simulator, a newly designed thermal gradient-type reactor. The results are satisfied: the flow path between the granite fragments filled in the reactor is plugged with hectorite gel formed by hydrothermal process of amorphous slurry comprising 2 weight % of hectorite compositon at 200°C and 250°C conditions.Such gel material for the underground high temperature conditions may be useful to make design of extracting huge geothermal energy through artificial fractures developed in the hot dry rock.

There have been several reports that photodesorption due to synchroton radiation from OFC copper chambers with machined surfaces is far lower than in stainless steel or aluminum alloy chambers. However, it is difficult to process machined surfaces for the inner surfaces of beam chambers. A surface treatment using broaching has been developed to cut the inner surface of the chamber. Tests of the photodesorption caused by synchrotron radiation in a small, broached, cylindrical cross-section chamber with a length of 30 cm have been reported. To adapt the broaching method to long chambers, prototype copper vacuum chambers with lengths of 1.8 m and 2 m have been fabricated. A chamber consists of a beam channel, a cooling channel, and a NEG pump channel. The beam channel, which has a hexagonal cross section, is broached. An ultimate pressure of 1 × 10 −8 Pa was obtained after bakeout at 200 °C for 24 h and NEG activation.

A 58-year-old male presented with malignant fibrous histiocytoma originating from the lateral wall of the orbit, manifesting as left exophthalmos and diplopia on left lateral gaze. Magnetic resonance (MR) imaging demonstrated the tumor extending into the left orbit and under the temporalis muscle. The tumor was isointense with muscle on T1-weighted MR images and was surrounded by a low-intensity rim, which was proved to be the capsule after histological examination. The tumor was completely removed after detaching the lateral orbital rim and zygomatic arch using the dismasking flap method. He underwent one course of CYVADIC chemotherapy and has demonstrated no recurrence for 1 year and 6 months postoperatively.

A new method for surface treatment of copper vacuum chamber has been developed to easily obtain lower photodesorption coefficients due to synchrotron radiation at low cost. An oxygen‐free high‐conductivity (OFHC) copper test chamber is extruded and degreased, then the inner surface is cut by broaching. The length of the test chamber is 300 mm and the outer diameter is 65 mm. For comparison, three OFHC copper test chambers are manufactured with different surface treatments. These treatments are (1) acid cleaning (pickling in a mixed solution of HNO3 and H2SO4, followed by passivation in a chromic acid with H2SO4), (2) broaching with oil, and (3) oil‐free broaching. These test chambers were exposed to synchrotron radiation with 4 keV critical energy from BL21 beamline at the Photon Factory 2.5 GeV storage ring at KEK. The photodesorption coefficients (N2 or CO equivalent) for the chamber treated with oil‐free broaching and for the chamber treated with acid cleaning are almost the same. However the decreasin...

[1] A fluid flow experiment was conducted on a granite sample containing two intersecting fractures. At constant confining pressure, water was supplied to the sample via a single inlet port, and the effluent was collected using four isolated outlet ports. The flow rate varied widely among these ports, indicating the formation of 3-D preferential flow paths (channeling flow), which likely occur in fractured rocks but have been considerably difficult to identify by existing methods. The novel concept of GeoFlow, a discrete fracture network model simulator in which fractures have a heterogeneous aperture distribution, has been developed to analyze such complex fluid flow. A fluid flow simulation was conducted using GeoFlow with aperture distributions within the two fractures, as determined using fracture surface topography data. Despite the simplicity of the simulation, GeoFlow revealed a 3-D channeling flow within the sample, which explains the general trend of the uneven outflows in the experiment.

The Laguerre density and its distribution function which represent the noise in communication systems with an optical amplifier are evaluated by the Cornish expansion and it is found that the result is sufficiently useful for practical applications. The variable transition, skewness, excess, and mode are used as figures of the difference between the Laguerre and Gaussian functions. Then the error rate and decision level on the optimum and quasi-optimum conditions of a digital on-off keying (OOK) communication system are analyzed. Assuming the noise to be Gaussian, the error rate is overestimated by about one order. This result agreed with one reported elsewhere.

Abstract A three dimensional numerical modeling coupled with X-ray Computed Tomography (CT) for fracture flow was applied to fractured granite core samples. One of the samples had an artificial single fracture, and the others had natural multiple fractures. A relationship between CT value and fracture aperture (fracture aperture calibration curve) was obtained by X-ray CT scanning for a fracture aperture calibration standard with varying the aperture from 0.1 to 0.5 mm. As a result, a linear relationship was obtained between CT value and fracture aperture. With the fracture aperture calibration curve, three dimensional distributions of CT values of the samples were converted into fracture aperture distributions to obtain fracture models of the samples. Porosities of the fracture models could provide good agreement with experimentally determined porosities for all the samples. By using the fracture models, a fluid flow simulation was also performed with a local cubic law-based fracture flow model. Numerical permeabilities by the flow simulation were much higher than experimentally determined permeabilities of the samples. It was however possible to match the numerical permeabilities with the experimental permeabilities for all the samples, by using a unique modification coefficient of 0.5 for the fracture aperture in the fracture flow model. With the modified flow model, it was possible to obtain detailed information of heterogeneities in fracture flow as well as permeabilities of the samples. Although the present X-ray CT scanning was performed at room temperature and pressure, it was expected that the numerical modeling had possibility to provide insights into heterogeneous nature of fracture flow in fractured reservoirs, such as channeling, as well as porosity and permeability, when the CT scanning was performed at reservoir conditions. Further studies on this kind of numerical modeling should provide simple and easy way to address heterogeneous fracture flow in reservoirs that can have impacts on productivity of wells, efficiency of recovery by water/gas flooding, and so on. Introduction Effective developments of oil/gas fractured reservoirs need well understanding of fracture flow characteristics in those reservoirs. Field and laboratory studies have suggested that fluid flow through a rock fracture is far from that of smooth parallel plates, due to channeling flow in a heterogeneous aperture distribution by rough surfaces [1–9]. When channeling flow occurs in a single fracture of granite, the area where flowing fluid exists is expected only 5–20% at confining pressures of up to 100 MPa, with various features in the preferential flow paths [9]. Against this background, we have recently developed a discrete fracture network model simulator, GeoFlow, in which fractures can have aperture distributions with natural heterogeneities [10]. Three dimensional fluid flow simulations for fracture networks by GeoFlow have demonstrated developments of three dimensional preferential flow paths in those fracture networks, and have suggested that performance of production well can be strongly affected by the heterogeneous fracture flow. Consequently, it should be considerably important to evaluate the heterogeneity and its impact for effective developments of fractured reservoirs.

Abstract The discrete fracture network (DFN) model simulation, in which the fracture network can have a natural heterogeneity, is one of the most effective approaches in fluid flow analyses for a fractured reservoir. In the DFN model simulation, the fracture is modeled by a pair of parallel smooth plates although real fractures have rough surfaces. However, numerous field and laboratory observations have suggested that fluid flow through a fracture occurred in specific preferential flow paths (channeling flow) due to a heterogeneous aperture distribution formed by the rough surfaces. The conventional DFN model simulation therefore gives us a serious concern about the reality. To address this concern, we have developed a new concept DFN model simulator, GeoFlow, in which the fracture can have the heterogeneous aperture distribution. Three dimensional fluid flow simulation was performed for a simple fracture network by both the conventional and the new concept DFN models. In the conventional DFN model simulation, the fracture had no aperture distribution, and fluid flow in the fracture plane was quite uniform. On the other hand, the GeoFlow simulation showed formation of three dimensional preferential flow paths in the fracture network. In addition, another GeoFlow simulation showed that productivities of the wells highly depended on their locations even when the wells intersected the same fracture. The productivities were considerably smaller when the wells intersected the regions with smaller aperture conductivities, where the preferential flow paths were difficult to form at the natural condition (no well condition). The results demonstrated occurrence of three dimensional channeling flow in fractured reservoirs, which should be addressed for effective developments of the reservoirs. Introduction Fluid flows through rock fractures in the Earth's crust have been a subject of interest for some time because rock fractures usually have much greater permeability than the rock matrix. Rock fractures are therefore recognized as the predominant pathways of resources and hazardous materials such as groundwater, oil/gas, geothermal fluids, and the high-level nuclear wastes. The fluid flow properties of rock fractures have been investigated with respect to the geological disposal of the high-level nuclear wastes. As a result, our understanding of the subsurface flow system has been greatly improved and has been applied to the development of geothermal and oil/gas fractured reservoirs. Recently, the prediction of flow and transport phenomena through rock fractures based on a precise modeling of the flow system in a fractured rock mass with natural heterogeneities has become increasingly important because recent environmental and energy problems require urgent solutions using underground space based on the safe and effective development of reservoirs. A modeling with a natural heterogeneity of a fracture network has been established by the Discrete Fracture Network (DFN) modeling technique [1–5]. In the DFN modeling, rock fractures have been described by parallel smooth plates. However, field and laboratory studies have suggested that fluid flow through a rock fracture is far from the fluid flow through parallel smooth plates, due to channeling flow in a heterogeneous aperture distribution by rough surfaces [6–14]. When channeling flow occurs in a single fracture of granite, the area where flowing fluid exists is expected only 5–20% at confining pressures of up to 100 MPa, with various features in the preferential flow paths [14].

The use of a probability density function expanded into Edgeworth series of an APD output current instead of a Gaussian density function aids in the development of a theory of an APD behavior that is both more rigorous and practical. The determination procedure for both the optimum multiplication factor and the optimum symbol decision level is described through application of the theory to bit-error-ratio evaluation in optical communication systems. The results reveal that the bit-error ratios are evaluated about two orders lower when Gaussian approximation is employed. The theory of an APD behavior with the series is used to estimate the bit-error-ratio degradations and floor effects on bit-error-ratio curves that result from echoes on the transmission lines of the forementioned communication systems. Finally, general results are obtained without any restrictions to echo amplitude or delay time.

Echoes, which are transmission waves arriving at a receiver later than the principal wave, arise from multiple reflections at discontinuous points, such as connectors, on a transmission line and cause intensity fluctuations onto a laser light to be received. The intensity fluctuations and its effect on bit-error ratios in binary on/off-keying (OOK) optical fiber communication systems are analyzed theoretically here. Analysis features and principal results are as follows: (i) a general theory is developed, including the case of short time delay; and it is shown that the bit-error ratio degradation decreases when the time delay is shorter than the coherence time of a laser light; (ii) the analysis has no restrictions to amplitude ratio of the echo to the principal wave, so that a critical value of an echo amplitude for floor effect and its corresponding floor values can be evaluated; and (iii) since bit-error ratios are obtained directly from the probability density function of intensity fluctuations, rigorous results are obtained. This paper considers PIN diodes in detail. Only results for the avalanche photodiode (APD) are presented.

Background We reported previously that some patients with aneurysmal subarachnoid hemorrhage (SAH) demonstrated an abrupt fall in blood pressure (FBP) during the acute period. We further examined this phenomenon in relation to several important clinical variables in a new series using multivariate analysis.

A set of leaf springs, a micrometer head, a bellows coupling, a ball‐bearing‐type reduction gear, and a stepping motor were coupled in series to realize the quick and fine approach of a specimen surface to a scanning tunneling microscope tip. The minimum tip–surface displacement by the coupled system is in the range of 20–40 A and the maximum approaching speed is 0.25 mm/s. At the final stage of approach a piezoelement brought the specimen to the tunneling region between the Pt–Ir tip and the specimen graphite surface. The material transfer from the specimen to the tip apex was revealed by the atom‐probe mass analysis of the apex after a trial approach at the speed of 0.4 μm/s. However, no overshooting current by a tip–specimen contact was noticed throughout the trial approach. The observed mass transfer without a sign of the contact was attributed to the long response times of the current amplifier and the feedback circuit monitoring the approach. No material transfer was noticed for 0.16 μm/s.

Variations of topographic and current images with bias voltages were examined utilizing the current imaging tunneling spectroscopy (CITS) and dual‐polarity tunneling imaging (DPTI) techniques. While the CITS and DPTI images of the Si(111)‐(7×7) reconstructed structure at the specimen voltage of +2 V and the DPTI image at −2 V are reliably reproducible exhibiting bright Si adatoms and dark corner holes, the CITS current image at −2 V often showed reversed contrast grey‐scale images with bright corner holes. The observed reversed image is explained as the result of the difference in the effective tunneling barrier and the surface state density of the tip apex and specimen, and also as the effect of the atomic arrangement and composition and profile of the tip apex.

Si(111) surfaces heated at 1300 °C show many steps and terraces exhibiting the (√3×√3) R 30°, c(4×2), (5×5), (7×7), and (9×9) reconstructed structures. A detailed study of the surface corrugation indicates that the observed maximum depth of the corner hole is 2.4 A and the trace of a scanning tip is close to the profile of the [111]‐oriented W tip with a single atom at the apex and the most desirable cone angle of ∼120°. Occasionally, anomalous, ordered structures appeared and were explained as the result of the scanning with two apex atoms 4.5 A apart, the distance between the nearest surface atoms of the W(111) plane.

Aperture structure and fluid flow of shear fractures with different shear displacement (1 and 5 mm), which were created in granite under different normal stress (20 and 60 MPa) for a shear plane, were evaluated for 10–100 MPa confining pressure, using high‐resolution numerical modeling technique. Aperture structure was heterogeneous and fluid flow occurred in preferential flow paths for all the shear fractures under the confining pressure. For shear fractures created under 20 MPa normal stress, aperture structure was characterized by contact points clustered in a few specific regions, and which caused clear channels where fluid flow occurred preferentially, despite of different shear displacement. On the other hand, for a shear fracture with 1 mm shear displacement, which was created under 60 MPa normal stress, aperture structure was characterized by no clear channel although large clustered contact points were observed, and which caused tortuous flow paths. Additionally, for a shear fracture with 5 mm shear displacement, which was also created under 60 MPa normal stress, aperture structure was characterized by smaller clustered contact points, and fluid flow occurred less tortuous flow paths.

Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.

In order to investigate effects of molecular behavior of water at interface on the rock surface, high temperature‐pressure cell (up to 400 °C and 50 MPa) was developed to measure infrared and Raman, which was attached with optical microscopy, therefore, in situ and microscopic measurements were enable at high temperature and pressure conditions. Infrared properties of thin film water and interfacial water at rock surface were measured. As a result of infrared spectroscopic measurements of thin film water, the broad peak at ca. 3360 cm−1 of infrared spectra, attributed to OH stretching mode of water molecular, was observed at room temperature and pressure. Continuous shift of the OH vibration mode was obtained from room to hydrothermal conditions. These results indicate that changes of molecular structure of the water were detected by using newly designed high temperature‐pressure cell. Compared with the result of infrared properties of thin film water, infrared properties of interfacial water at rock surface exhibit different trend: the peak position shifted to higher wavenumber with increasing temperature and did not shift with pressure. Molecular structure of interfacial water on the rock and rock‐forming mineral at elevated temperatures and pressures were not only changes due to physical conditions such as temperature and pressure but also interaction between interfacial water and solid rock materials.