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A dichlorosilane gas and a trichlorosilane gas in ambient hydrogen were evaluated to show their different gas flow motions in a slim vertical cold wall chemical vapor deposition reactor for the Minimal Fab system. This evaluation was performed for improving and controlling the film qualities and the productivities, using two quartz crystal microbalances (QCM) installed at the inlet and exhaust of the chamber by taking into account that the QCM frequency corresponds to the real time changes in the gas properties. Typically, the time period approaching from the inlet to the exhaust was shorter for the trichlorosilane gas than that for the dichlorosilane gas. The trichlorosilane gas was shown to move like plug flow, while the dichlorosilane gas seemed to be well mixed in the entire chamber.

A silicon epitaxial growth process in a trichlorosilane-hydrogen system was evaluated using a quartz crystal microbalance (QCM) placed at the exhaust of a chemical vapor deposition reactor designed for the Minimal Fab. The QCM showed two types of the frequency decrease behaviors, that is, i) a quick shift due to the gas property change caused by the trichlorosilane gas introduction into the ambient hydrogen and ii) the continuous and gradual decrease due to the byproduct deposition on the QCM surface during the silicon epitaxial growth. Because both i) and ii) showed a relationship with the silicon epitaxial growth rate, the in-situ information obtained by the QCM was expected for the real time monitoring of the film deposition process.

Effective process conditions to utilize a slim vertical silicon chemical vapour deposition reactor were studied. Based on a numerical analysis taking into account the gas flow, heat and species transport, particularly over a wide range of the trichlorosilane gas concentrations from 1% to 40% in ambient hydrogen, a heavy and cold gas was shown to quickly go downward to the hot wafer surface through the slim vertical gas channel. The gas phase near the wafer was sufficiently cooled to produce a cold wall thermal condition which enabled the trichlorosilane gas consumption only at the wafer surface, even in a non-axisymmetric and non-steady condition. The slow wafer rotation, less than 30 rpm, had a considerable effect, such as that increasing the gas phase temperature gradient for suppressing the gas phase reaction.

The gas flow, heat and species transport in a slim vertical silicon chemical vapor deposition reactor for Minimal Fab were evaluated by a numerical analysis. The influences of the inlet gas flow condition on the gas flow direction and the gas phase temperature in the reactor were studied. When the gas flow rate was minimized, natural convection transports the precursor of trichlorosilane gas to the wafer surface. Because the wafer rotation, even very slow at 4 rpm, adjusted the gas flow to shrink the hot region height above the wafer, the gas phase reaction was moderated for preparing the specular surface of the epitaxial film.

A small-sized reactor for producing a silicon epitaxial film on a half-inch silicon wafer was studied, taking into account the heat transport near the wafer. The wafer temperature slowly changed over a long time period when the reflector was made of thick plates. In contrast, when thin plates were employed as the reflector material, the wafer temperature quickly increased and easily reached a steady state. Thus, the reactor parts set near the wafer should be small, slim and thin. With the help of wafer rotation and a highly heat-conductive susceptor, a symmetrical and uniform silicon epitaxial film thickness profile could be obtained. © The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0251605jss] All rights reserved.

Chlorosilane gas transport in ambient hydrogen in a slim vertical cold wall chemical vapor deposition reactor was real-time monitored using a quartz crystal microbalance (QCM) using its behaviour responding to the properties of the gas mixture. The QCM frequency quickly decreased by introducing the trichlorosilane gas, while it slowly decreased by the dichlorosilane gas. The QCM frequency behavior was explained by the gas flow condition, such as the plug flow and recirculating flow, in the reactor. The relationship was consistent with the gas flow calculations, because the heavy and light gases could directly flow downward and recirculate, respectively, in the chamber due to natural convection. The information obtained from the QCM frequency behavior is expected to be utilized for the real-time gas monitoring and for the process design.

A chemical vapor deposition reactor for producing thin silicon films was designed and developed for achieving a new electronic device production system, the Minimal Manufacturing, using a half-inch wafer. This system requires a rapid process by a small footprint reactor. This was designed and verified by employing the technical issues, such as (i) vertical gas flow, (ii) thermal operation using a highly concentrated infrared flux, and (iii) reactor cleaning by chlorine trifluoride gas. The combination of (i) and (ii) could achieve a low heating power and a fast cooling designed by the heat balance of the small wafer placed at a position outside of the reflector. The cleaning process could be rapid by (iii). The heating step could be skipped because chlorine trifluoride gas was reactive at any temperature higher than room temperature.

We have succeeded in growing single crystals of the oxide spinels GeNi 2 O 4 and GeCo 2 O 4 . Both materials have the pyrochlore lattice, and show antiferromagnetic-like order. Thus, magnetic frustrations and relevant phenomena are strongly expected. To obtain single crystals of these materials, we employed a conventional floating-zone method. For the crystal growth of GeCo 2 O 4 , no severe difficulties were found. For GeNi 2 O 4 , it was necessary to avoid intense the evaporation of GeO 2 due to the higher melting point of GeNi 2 O 4 than that of GeCo 2 O 4 . Therefore, it was quite difficult to obtain single crystals of GeNi 2 O 4 by the same procedure as GeCo 2 O 4 . We show the importance of the starting composition and crystal growth atmosphere for both spinels.

We report on the crystallographic structure of the layered perovskite iridate Sr3Ir2O7, investigated using transmission electron microscopy. The space group was found to be Bbcb ( D 2 h 22 , No. 68 in the International Tables for Crystallography) at 315 K. A very fine twin structure with 90° rotation with respect to the c-axis was observed. The crystal structure at temperatures lower than 285 K, where a phase transition from paramagnetism to weak ferromagnetism is known to occur, was also examined. There was no difference in the extinction rule for the diffraction patterns between the two phases. We conclude that there is no change in the space group for this magnetic transition. There still remains the possibility of a change in the rotation angle of IrO6 octahedrons and a corresponding change in the interatomic distance between Ir and O, though.

We report a uniaxial pressure-dependence of magnetism in layered perovskite strontium ruthenate Sr3Ru2O7. By applying a relatively small uniaxial pressure, greater than 0.1 GPa normal to the RuO2 layer, ferromagnetic ordering manifests below 80 K from the enhanced-paramagnet. Magnetization at 1 kOe and 2 K becomes 100 times larger than that under ambient condition. Uniaxial pressure dependence of Curie temperature T_C suggests the first order magnetic transition. Origin of this uniaxial-pressure induced ferromagnetism is discussed in terms of the rotation of RuO6 octahedra within the RuO2 plane., 8 pages, 3 figures. to be published in Journal of the Physical Society of Japan, vol.73, No.5 (2004)

We report a single-crystal growth technique for strontium ruthenates. Strontium ruthenates exhibit intriguing magnetic properties such as spin-triplet superconductivity in Sr 2 RuO 4 . To obtain pure single crystals of strontium ruthenates (Sr 2 RuO 4 , Sr 3 Ru 2 O 7 and SrRuO 3 ), we employed a conventional floating-zone method. For the crystal growth of Sr 2 RuO 4 , no severe difficulties are known. Even in air, it is possible to grow that single crystal from the molten zone of polycrystalline bar of Sr 2 RuO 4 . However, for Sr 3 Ru 2 O 7 and SrRuO 3 , it is impossible to obtain single crystals by the same procedure. We herein show the importance of oxygen-partial pressure in the atmosphere for the crystal growth of strontium ruthenates based on our successful results.

The concept of quantum criticality is proving to be central to attempts to understand the physics of strongly correlated electrons. Here, we argue that observations on the itinerant metamagnet Sr 3 Ru 2 O 7 represent good evidence for a new class of quantum critical point, arising when the critical end point terminating a line of first-order transitions is depressed toward zero temperature. This is of interest both in its own right and because of the convenience of having a quantum critical point for which the tuning parameter is the magnetic field. The relationship between the resultant critical fluctuations and novel behavior very near the critical field is discussed.

The crystal structure of the ruthenate Sr{sub 3}Ru{sub 2}O{sub 7} as a function of temperature (5--305 K) and pressure (ambient -0.62 GPa) was studied by neutron diffraction. Upon cooling, the lattice parameter c and the rotation angle of the oxygen octahedra {phi} increase for 305K>T>50K, and decrease for 20K>T>5K. As pressure is applied at room temperature, the outer apical Ru-O bond expands. This remarkable behavior is discussed in terms of modification of the occupation of energy levels of the Ru{sup 4+} ion in the crystalline electric field of the oxygen octahedron and a crossover to Fermi-liquid behavior at low temperature. The very anisotropic thermal expansion leads, in sintered powder samples, to a high degree of strain, which is relieved somewhat with each cooling cycle.

Electronic structure of the monolayer strontium ruthenate Sr 2 RuO 4 was investigated by high-resolution angle-resolved photoemission spectroscopy. We present photon-energy ( h ν ) dependence of the electronic structure near the Fermi level along the Γ M line. The h ν dependence has shown a strong spectral weight modulation of the Ru 4 d xy and 4 d zx bands.

We have found that the quasi-two-dimensional superconductor $\mathrm{Sr}{}_{2}\mathrm{RuO}{}_{4}$ with the intrinsic transition temperature ${T}_{\mathrm{c}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.5\mathrm{K}$ exhibits a remarkable enhancement in ${T}_{\mathrm{c}}$ up to 3 K, if lamellar microdomains of ruthenium metal are embedded. Measurements of the anisotropy in the upper critical fields indicate that the 3-K superconductivity is sustained essentially in the layered structure of $\mathrm{Sr}{}_{2}\mathrm{RuO}{}_{4}$. We suggest that the enhanced interlayer coherence provided via metallic Ru plays a key role in the doubling of ${T}_{\mathrm{c}}$.

Cu oxide has been deoxidized in an extremely low oxygen partial pressure atmosphere. The oxygen was evacuated to 10-28 atm using a newly developed oxygen reduction system (ORS). It was experimentally demonstrated that the surface oxide of Cu film was completely removed by exposure to such an environment at 200 °C. The proposed deoxidization reaction can be used as a new Cu surface cleaning technique.

We have prepared rare earth oxysulfides (PrO)CuS and (NdO)CuS in order to introduce magnetic moments into the non-magnetic p-type semiconductor (LaO)CuS. Both compounds are semiconductors with high electrical resistivity, and show the paramagnetic behavior. The temperature dependence of the magnetic susceptibility is well explained by the trivalent rare earth ion. However, it deviates from simple Curie Wiess law below 100 K due to the crystal field effect on rare earth ions. We have succeeded to reproduce their magnetic properties by the calculation taking the crystal field effect into account using the operator equivalent method.

We have synthesized several ternary uranium gallides. UNiGa 2 is an enhanced Pauli paramagnet, whereas UPd 2 Ga, UNiGa 3 and UNiGa 4 undergo antiferromagnetic transitions at 6.5, 39 and 42 K, respectively. In UCu 3+ x Ga 2 − x (0.1 ⩽ x ⩽0.8) T N ( x ) assumes a maximum of 17.4 K near x =0.3 and a nonmagnetic heavy-fermion state evolves with further increase in x . Metamagnetic transitions occur in UNiGa 3 , UNiGa 4 and UCU 3.1 Ga 1.9 between 5 and 9 T at 4.2 K.

We wish to report that iridium complexes [IrCl(CO){sub 3}]{sub n} and Ir{sub 4}(CO){sub 13} catalyze the reaction of alkenes with a hydrosilane HSiR{sub 3} and carbon monoxide (eq 1) to yield enol silyl ethers of acylsilanes. This unprecedented reaction results in regioselective introduction of carbon monoxide into the terminal carbon atom of alkenes, forming a siloxy(silyl)methylene unit(=C(SiR{sub 3})-OSiR{sub 3}). The present Ir-catalyzed reaction represents the first example of formation of acylsilane derivatives form the HSiR{sub 3}/CO combination. The new catalytic reaction can be applied to a wide variety of terminal alkenes. The acetal, cyano, and epoxide functional groups remain intact through this catalysis. The mechanism of the reaction may involve the possible intervention of a siloxycarbyne comple intermediate. 12 refs., 1 fig., 1 tab.

The hydrosilylation of oxygen-containing olefins in the presence of Co2(CO)8 was carried out. The Co2(CO)8-catalyzed hydrosilylation of allyl acetate with HSiEt2Me is consistent with proceeding via a silylmetalation mechanism rather than a classical hydrometalation (Chalk-Harrod mechanism).

A new compound, CuIr2Te4, has been successfully synthesized. The X-ray experiments indicate that this new compound has defect NiAs structure of trigonal symmetry with space group P 3 m 1 . The resistivity ρ and the magnetic susceptibility χ of CuIr2Te4 have revealed the existence of hump-shaped maxima around 250 K on heating, 190 K on cooling, exhibiting the temperature hysteresis. This anomalous behavior originates presumably from a charge-density wave formation with the partial gap at the Fermi level.

The ultraviolet photoemission spectrum of a layered-perovskite superconductor Sr 2 RuO 4 around the Fermi level is considerably different from the density of states obtained by a band calculation based on the local density approximation. Although the significant spectral weight redistribution is considered to be evidence of the large electron correlation in this system, the effective mass is not so enhanced. A possible scenario to coordinate both these phenomena is discussed.

The mechanism whereby cytolytic lymphocytes protect themselves from killing mediated by their own cytotoxic protein, perforin, was studied. Perforin attached to killer lymphocyte surface in reversible manner even in the presence of Ca2+ while it bound to target cell surface in irreversible way. Moreover, the association rate constant for perforin-killer lymphocytes was different from that for perforin-target cells. These facts suggested that perforin binds to different molecule between on the killer cell membrane and target cell membrane. On the other hand, in killer lymphocytes treated with tunicamycin, an inhibitor of glycosylation, their resistance against perforin was significantly decreased. N-Glycosidase F-treated killer lymphocytes also lost their resistance ability against perforin. These findings suggested that certain carbohydrates of some glycoproteins at the cell surface are essentially important for protection of killer cell from perforin. Furthermore, some oligosaccharides such as 4-O-s-Dgalactopyranosyl-D-galactopyranose and 4-O-s-D-galactopyranosyl-D-fructose deactivated the perforin activity. These oligosaccharides had a same set of functions for hydrogen bond donor and acceptor.

The magnetic properties of the bilayer ruthenate Sr3Ru2O7 as investigated by neutron scattering are reviewed. No long range magnetic order is observed down to 40 mK, but instead a metamagnetic transition which is induced by a moderate magnetic field at low temperatures. In zero field, the spectrum of the spin fluctuations reveals that at low temperature the magnetic correlations in this material are antiferromagnetic in nature. The wavevectors at which the signal is strongest are incommensurate and appear to be determined by Fermi surface nesting. The low energy scale of the fluctuations suggests that they are intimately related to the metamagnetic transition.

We have investigated Ru, Sr atoms in strontium ruthenates: SrRuO3, Sr2RuO4 and Sr3Ru2O7 with X-ray absorption fine structure (XAFS) spectroscopy. These three strontium ruthenates have remarkable different properties. We reported that valences of ruthenium ion in these strontium ruthenates exhibit the same number of four. And the valence of strontium ion in these also indicates the same number of two. Therefore, the different magnetic properties of these strontium ruthenates do not come from atomic valences but come from these crystal structures, inter atomic distance and strains.

In order to extract the intrinsic magnetic correlations in Sr 2 RuO 4 , we have performed magnetization measurements under uniaxial pressures ( p 2 plane. The single crystalline sample grown by a floating-zone method has been used. The results indicate that the magnetization remains paramagnetic up to the maximum pressure without showing any sign of substantial magnetic transitions. Larger pressure is probably necessary to induce ferromagnetic or antiferromagnetic ordering associated with the nature of superconductivity.

High-field ESR measurements of cubic spinel GeCo2O4 single crystals have been performed using the pulsed magnetic field up to 16 T in the temperature range from 300 K to 1.8 K. Dynamical resonance shifts due to antiferromagnetic ordering were observed. New AFMR modes appear below 3 K. High-field ESR measurements reveal complicated phase structures and field-induced magnetic phases below TN, suggesting new temperature field phases.

We studied magnetic properties of Ge-based spinel oxides Ge(Fe1−xCox)2O4 to verify the frustration effect. We discovered that the spin-glass-like behavior in Ge(Fe1−xCox)2O4 exists in 0 ≤ x ≤ 0.9, and coexists with the antiferromagnetic order in 0.1 ≤ x ≤ 0.9. Taking into account the coexistence of spin molecular excitations (frustration effect) and antiferromagnetic order in GeCo2O4 (x = 1), the spin-glass-like behavior coexisting with the antiferromagnetic order in Ge(Fe1−xCox)2O4 might be attributed to the freezing of the spin molecules by the substitution of Fe for Co.

We have investigated the electronic structures of the parent compound of an iron chalcogenide superconductor TlFe2Se2 by bulk-sensitive photoemission spectroscopy (PES). Valence-band PES demonstrates the energy gap opening at the Fermi level due to the shift of Fe 3d state to the higher binding energy side as compared to the calculated density of states, being consistent with the insulating behaviour in transport measurements.

Polycrystalline NiSe, NiTe, CoSe, and CoTe have been synthesized by two methods, i.e., (1) the solid-state reaction in an evacuated quartz ampoule (QA) and (2) the high-pressure (HP) technique (HP) in a Au capsule using a cubic anvil cell. All the obtained samples have the nickel arsenide-type hexagonal crystal structure, except CoTe (HP), and their estimated lattice parameters, a and c, show almost the same values within 0.8% in comparison between samples prepared by the QA method and those by the HP method. On the other hand, a distinct difference between samples prepared by QA and HP processes is found in the magnetization of NiSe and NiTe. In particular, for NiTe, the temperature dependence of magnetization indicates two transition temperatures at about 20 and 130 K in samples prepared by the HP process. However, samples of NiTe x (x = 0.5, 0.66, 0.82, 1, 1.22, and 2) and NiTe containing Au prepared by QA process do not show similar magnetic orders in the temperature range between 2 and 300 K. Also, samples of NiSe (HP) show magnetic transition at ∼20 K, while those of NiSe (QA) show a magnetic inflection point at ∼10 K. To the best of our knowledge the remarkable difference in magnetic properties caused by the method of synthesis has not been reported. In this paper, we present comparative experimental results of magnetic, electric, and specific heat measurements of samples prepared by the two methods. A possible explanation for such a substantial difference in magnetic interaction will be discussed.

In MgV2O4 with normal spinel structure (AB2O4), there is magnetic frustration of V3+ (3d2+) ions located on B-sites, if an antiferromagnetic interaction among B-site spins is essential for its magnetism. The excess Mg substituted materials such as Mg1+xV2−xO4, may construct isolated magnetic triangular lattices, because some of B-sites forming magnetic tetrahedral lattice are substituted by non-magnetic Mg ions, while the normal spinel MgV2O4 contains tetrahedral magnetic ion networks. Here, we have succeeded in growing single crystals of Mg–V–O system spinel oxide by conventional floating-zone method. The valence numbers and abundance ratio of V ions in the single crystal were estimated by wavelength-dispersive X-ray fluorescence analysis and X-ray photoelectron spectroscopy analysis. Although the composition ratio was Mg:V = 1:2, a small amount of Mg and V ion partly replace each other between A- and B- sites in this crystal. The composition formula is described as (Mg1−xVx)(V2−xMgx)O4. The single crystal shows magnetic transition at around 12 K and large negative antiferromagnetic Weiss temperature about −840 K, and the frustration parameter f = 70 estimated by those temperatures. This result suggests the existence of strong magnetic frustration in our material.

Unusual low-temperature properties of uranium-based intermetallic compounds originate from 5f electrons of uranium atoms, which have an intermediate nature between itinerant and localized characters. The 5f states are more extended in space than 4f orbits in rare earth compounds. Usually the 4f electrons of rare earth atoms are well localized inside the 5s and 5p shells. On the other hand, the 5f electrons are not so delocalized as compared with d electrons in transition metals, for which an itinerant description is suitable.

The hydrosilylation of oxygen-containing olefins in the presence of Co2(CO)8 was carried out. The Co2(CO)8-catalyzed hydrosilylation of allyl acetate with HSiEt2Me is consistent with proceeding via a silylmetalation mechanism rather than a classical hydrometalation (Chalk-Harrod mechanism).

Ultrasound velocity measurements of the cubic spinel GeCo2O4 in the single crystal have been performed for the investigations of shear and compression moduli. The shear moduli reveal the absence of Jahn-Teller activity despite the presence of the orbital degeneracy in the Co2+ ions. This Jahn-Teller inactivity indicates that the intersite orbital-orbital interaction is much stronger than the Jahn-Teller coupling. The compression moduli reveal that the dominant path of the exchange interactions for the antiferromagnetic transition lies in the [111] direction. This exchange-path anisotropy is consistent with the antiferromagnetic structure with the wave vector q ? [111], suggesting the presence of bond frustration among several ferromagnetic and antiferromagientic interactions. In the JT-inactive condition, the bond frustration can be induced by geometrical orbital frustration of t2g-t2g interaction between the Co2+ ions which can be realized in the pyrochlore lattice of the high spin Co2+ with t2g -orbital degeneracy. In GeCo2O4, the tetragonal elongation below TN releases the orbital frustration by quenching the orbital degeneracy.

Transition metal oxides with spinel crystal structure exhibit intriguing and non trivial magnetic phenomena owing to magnetic frustration between spins having antiferromagnetic coupling interaction on triangle or kagome lattice. GeCo2O4(GCO) and GeNi2O4(GNO), which belong to above category, are very rare normal spinels containing Ge ion. Both reveal antiferromagnetic-like phase transitions at 20 K and 12 K, respectively. According to previous neutron and x-ray diffraction measurements, GNO keeps its cubic structural symmetry down to 2 K which is not natural because such a magnetic transition tends to associate with symmetry breaking structural transitions. In order to know whether the structural transition or symmetry change occur or not at the magnetic transition in detail, convergent beam electron diffraction measurements is employed for the compounds.

We have newly synthesized two distinct layered ruthenates of Ca2RuO4. They are both related to Sr2RuO4, the layered perovskite superconductor (Tc ≈ 1K) without copper. In contrast with the highly correlated metal Sr2RuO4, both phases of Ca2RuO4 are Mott insulators.

Single crystals of a highly conductive oxide SrMoO3 have been grown by a floating-zone method under argon atmosphere with ultralow oxygen partial pressure p(O2)∼10−25atm. The obtained single crystals of SrMoO3 reveal quite low resistivity at 300 K ρ(300K)=5.1μΩcm, which is the lowest to date in the values of ρ(300K) of all the oxides. Resistivity and specific heat data suggest that electrons in SrMoO3 behave as the Fermi liquid (correlated electron), and that its low resistivity is due to the extremely small electron-phonon interaction in SrMoO3.

Specific heat of UCu 3+x Ga 2−x (0.1≦x≦0.8) has been measured in a wide temperature range from 1.3 to 250 K. The experiment clarified the systematic x -dependence of the Sommerfeld coefficient γ and the antiferromagnetic transition temperature T N . This indicates a competition between Kondo effect and RKKY interaction even in the uranium system.

We wish to report that iridium complexes [IrCl(CO){sub 3}]{sub n} and Ir{sub 4}(CO){sub 13} catalyze the reaction of alkenes with a hydrosilane HSiR{sub 3} and carbon monoxide (eq 1) to yield enol silyl ethers of acylsilanes. This unprecedented reaction results in regioselective introduction of carbon monoxide into the terminal carbon atom of alkenes, forming a siloxy(silyl)methylene unit(=C(SiR{sub 3})-OSiR{sub 3}). The present Ir-catalyzed reaction represents the first example of formation of acylsilane derivatives form the HSiR{sub 3}/CO combination. The new catalytic reaction can be applied to a wide variety of terminal alkenes. The acetal, cyano, and epoxide functional groups remain intact through this catalysis. The mechanism of the reaction may involve the possible intervention of a siloxycarbyne comple intermediate. 12 refs., 1 fig., 1 tab.

Changes of bile composition in gallbladder bile and serum chemistries were investigated in nine dogs after proctocolectomy and ileoanal anastomosis, using an interposed jejunal segment as a neorectum. A significant decrease in cholic acid and an increase in deoxycholic acid were observed 24 weeks after the operation, although there was no significant change of total bile acid and phospholipids in the bile. Concentration of cholesterol and cholesterol saturation index in bile increased after total proctocolectomy. Although serum triglyceride levels became lower compared with the nontreated control group, concentrations of total protein, serum cholesterol, total lipids, blood sugar, and electrolytes showed no significant difference. This operative procedure apparently did not impair intestinal absorption of bile acid, but did increase the biliary cholesterol saturation index.

The procedure for predicting digestive enzyme stability in the solid state was further investigated by utilizing the Weibull distribution function, which needs two mathematically meaningful parameters, m and k. These parameters could be estimated by graphic calculation. If the parameter m is independent of temperature, the Arrhenius plots of (1/m) 1nk versus 1/T are linear since k1/m is proportional to the inactivation rate constant. The parameter k could be estimated by extrapolating to the desired temperature in the Arrhenius plots and the activation energy could be determined from the slope of this line. These parameters, m and k, made it possible to predict the inactivation ratio of enzymes in the solid state. By comparing the predicted value of the inactivation ratio with the observed value under controlled conditions, it was shown that the proposed method is accurate and useful for studies on enzyme stability in the solid state.

The Weibull distribution function was applied to solid-state enzyme inactivation. On Weibull probability paper (within a narrow range), the plots of the accumulated inactivation ratio of each enzyme versus time regressed to a straight line. The parameters m and k, which correspond to the type and rate of the type and rate of the inactivation, were characteristic of each enzyme. The effect of temperature and parameter reproducibility are discussed.