CH Content Research Articles

Distinctive features of operation of an internal combustion engine running on hydrogen-containing fuels

Experimental investigations have been carried out on an internal combustion engine with hydrogen added to the hydrocarbon fuel, i.e., gasoline. The possibility of improving the energy and environmental indices in the case of hydrogen feed to the engine’s air path has been shown. It has been established that increase in the fraction of hydrogen in the fuel mixture causes the operating process of the engine to improve, with the result that the flow rate of gasoline as a function of the H2 fraction decreases by nearly 70%. Considerable reduction in the content of CO, CO2, and CH (of approximately 5–60% depending on the amount of the added H2) is observed. However, adding hydrogen to the fuel-air mixture leads to an increase in the content of nitric oxides in the combustion products because of the growth in the velocity of propagation of the flame and increase in the combustion temperature.

Treatment of food processing wastewater in a full-scale jet biogas internal loop anaerobic fluidized bed reactor

A full-scale jet biogas internal loop anaerobic fluidized bed (JBILAFB) reactor, which requires low energy input and allows enhanced mass transfer, was constructed for the treatment of food processing wastewater. This reactor has an active volume of 798 m(3) and can treat 33.3 m(3) wastewater per hour. After pre-treating the raw wastewater by settling, oil separating and coagulation-air floating processes, the reactor was operated with a relatively shorter start-up time (55 days). Samples for the influent and effluent of the JBILAFB reactor were taken and analyzed daily for the whole process including both the start-up and stable running periods. When the volumetric COD loading fluctuated in the range of 1.6-5.6 kg COD m(-3) day(-1), the COD removal efficiency, the volatile fatty acid(VFA)/alkalinity ratio, the maximum biogas production and the content of CH(4) in total biogas of the reactor were found to be 80.1 ± 5%, 0.2-0.5, 348.5 m(3 )day(-1) and 94.5 ± 2.5%, respectively. Furthermore, the scanning electron microscope (SEM) results showed that anaerobic granular sludge and microorganism particles with biofilm coexisted in the reactor, and that the bacteria mainly in bacilli and cocci were observed as predominant species. All the data demonstrated that the enhanced mass transfer for gas, liquid and solid phases was achieved, and that the formation of microorganism granules and the removal of inhibitors increased the stability of the system.

Early age properties of cementitious materials by electrical resistivity measurement

Three cement pastes were prepared with the fixed water-binder ratio and different fly ash contents. The compression test and electrical resistivity measurement of the paste mixes were conducted during 48 h. The changes of the CH content and the non-evaporable water content in the cement-fly ash hydration systems with time were obtained by the thermal gravimetric analysis. The experimental results show that dilution effect of fly ash as micro-filler is dominant mechanism before 48 h, which appears to decrease in the CH content and the non-evaporable water content, also in compressive strength and electrical resistivity, with the increase of fly ash replacement. The relationships between CH content, non-evaporable water content and electrical resistivity show that electrical resistivity can be the indicators of hydration products CH and non-evaporable water. The correlation of the compressive strength fc and the electrical resistivity ρ can be obtained as fc=8.3429 ρ = 6.7088 for the period of 48 h. The early age compressive strength can then be predicted by electrical resistivity measurement.

The influence of environmental factors and nutrient concentrations in tissues of the seaweed Ahnfeltia tobuchiensis (Rhodophyta: Ahnfeltiales) on the primary production and dark respiration of its population

Complex investigations of the influence of environmental factors, viz., the temperature, photosynthetically active radiation (PAR), ambient seawater concentrations of ammonium (NH4), and orthophosphate (PO4), as well as the contents of organic carbon (C), nitrogen, phosphorus, and a-chlorophyll (Ch) on the rate of photosynthesis (Pn) and dark respiration (Rd) in the tissues of the unattached red seaweed Ahnfeltia tobuchiensis (Rhodophyta: Ahnfeltiales) population, were performed in the summers of 2000 and 2008 in Izmeny Bay (Kunashir Island) under in situ conditions. The dependence of photosynthesis on PAR intensity (P-I dependence) is described by the equation of a hyperbolic tangent. The population of A. tobuchiensis forms a layer up to 50 cm thick with an area of 23.3 km2 and a biomass of 125 000 tons. The Pn rate of seaweed population during daylight hours varies within a wide range, with an average of 1.04 mg O2 O2/(gdry weight h) and largely depends on PAR intensity and availability (r = 0.70–0.98). The maximum photosynthesis rate (Pmax) is substantially defined by the ambient concentration of NH4 (r2 = 0.91, p < 0.01). The rate of Rd during the night is on average 0.1 mg O2/(gdry weight h) and mainly depends on the content of Ch in seaweed tissues (r2 = 0.83, p < 0.01), which, in its turn, is regulated by the ambient concentration of PO4 (r2 = 0.86, p < 0.01). With average biomass values of 5.4 kg/m2 or 1.8 kgdry weight/m2, the net primary production (Pn) of seaweed population is estimated to be on average 22.5 g O2/(m2 day) or 8.4 g C/(m2 day). Based on these indices, the investigated population is one of the most productive ecosystems of the World Ocean. It is supposed that such indices of the A. tobuchiensis population are attained due to the highly efficient use of weak light and a low light-saturation level of photosynthesis, compared to other seaweeds.

Effects of soil factors on active component content ofChrysanthemum morifolium

To study the effects of soil factors on the active component content of Chrysanthemum morifolium and screen out the leading factors. The active component of water soluble extracts, flavonoids, phenolic compounds and mineral elements were determined and chemical properties and mineral elements of soil were analyzed for studying the effects on Ch. morifolium through correlation, stepwise regression, path and grey correlation analysis. Soil available P and K were the most important factors that affected the active component content of Ch. morifolium, followed by urease, phosphatase and invertase activities and organic matter. The mineral elements in Ch. morifolium and in soil correlated well, P and K were enriched in the plant mostly, followed by Cd, Ca, Zn, Cu. The main leading factors of mineral elements in soil were P and K, followed by Fe, Cu and Zn. Soil was one of the important factors which affected the active component content of Ch. morifolium.

Hydrogen production from steam reforming of ethanol using a ceria-supported iridium catalyst: Effect of different ceria supports

Catalytic activity of a ceria-supported Iridium (Ir/CeO 2) catalyst was investigated for steam reforming of ethanol within a temperature range of 300–500 °C. Three types of ceria were chosen to prepare the catalyst: commercial [assigned as CeO 2(C)] and prepared [using a simple reduction–oxidation method, CeO 2(R), and another combined with ultrasonic irradiation, CeO 2(U)] ceria. The Ir/CeO 2 catalyst with Ir loading of 2 wt.% was prepared by deposition–precipitation using iridium chloride (IrCl 3) as a precursor at 75 °C and pH = 9 (adjusted with 0.25 M Na 2CO 3). Catalytic activities toward the steam reforming of ethanol (SRE) were tested in a fixed-bed reactor. In order to better understand the effect of activation conditions of a catalyst on the reforming of ethanol, reduction pretreatment at 200 and 400 °C (assigned as H 2 and H 4) were conducted. The results indicated that only less sintering influences the catalytic activities for high temperature reduction. The ethanol conversion approached completion around 450 °C via reduction pretreatment for Ir/CeO 2(U) and Ir/CeO 2(C) samples under H 2O/EtOH molar ratio of 13 and 22,000 h −1 GHSV. Not only was a high dispersion of both catalysts present but also no impurities (e.g., boron) interfered with the catalytic activities. The hydrogen yield (H 2 mole/EtOH mole) exceeds 5.0 with less content of CO and CH 4 (<2%).

Anti-hyperlipidemic activity of spider brake (Pteris multifida) with rats fed a high cholesterol diet

This study evaluates the possible potency of the anti-hyperlipidemic effect of spider brake [(Pteris multifida Poiret (Pteridaceae)]. We investigated this by feeding the hyperlipidemic Sprague-Dawley rats, caused by a high cholesterol diet, with lyophilized powder of spider brake (LSB) and compared the result with the rats fed with β-sitosterol. The results indicated that the administration of lyophilized powder of spider brake (LSB) lowered the hyperlipidemic level on rats. The relative weights of the liver, adipose tissue, and relative adipose tissue of 10% substitutions of LSB group (LSB-10) showed a significant decrease (P < 0.05) by 6%, 15.9%, and 14.3% in contrast to the untreated counterparts (control), respectively. A significantly lower (P < 0.05) plasma TG, low density lipoprotein cholesterol, low density lipoprotein cholesterol/high density lipoprotein cholesterol ratio, liver CH, and TG contents were also observed in LSB-10 compared to the untreated counterparts (by 36.8%, 21%, 18.7%, 10.2% and 14.3% reduction, respectively). Simultaneously, the wet fecal weight, dry fecal weight, nitrogen compounds, excretion of neutral steroids, and bile acids significantly (P < 0.05) increased by 9.6%, 10.6%, 23.7%, 9.7%, and 3.4% respectively. The results showed that LSB could cause not only a reduction in CH and TG, but also could increase the excretion of lipids and metabolic by-products via the intestinal tract.

Structure alteration of lignin in corn stover degraded by white-rot fungus Irpex lacteus CD2

Lignin was isolated from corn stover degraded by Irpex lacteus CD2 to better understand how white-rot fungi decomposed corn stover lignin, and the structure alterations were analyzed by elemental analysis, FTIR, 13C NMR, 1H NMR, and UV spectra. These investigations illustrate significant structure differences between degraded and undegraded corn stover lignin that, in I. lacteus CD2 degraded lignin, aliphatic hydroxyl groups decreased remarkably, while conjugated carbonyl groups increased obviously. Moreover, the content of etherified guaiacyl units enhanced nearly twice, with the content of etherified syringyl units declining simultaneously. The increasing content of CH 3 in ArOCH 3 and the decreasing contents of guaiacyl and syringyl units were also observed in the degraded lignin, supposed to be the result of aromatic ring cleavage. By isolating lignin from degraded corn stover, the research demonstrates lignin structure differences contributed by white-rot fungus I. lacteus CD2 more profound and clear than investigations carried out by researching on lignin model compounds.

Hydrogen-rich gas from catalytic steam gasification of municipal solid waste (MSW): Influence of steam to MSW ratios and weight hourly space velocity on gas production and composition

The present work deals with a study coupling experiments and modeling of catalytic steam gasification of municipal solid waste (MSW) for producing hydrogen-rich gas or syngas (H 2 + CO) with calcined dolomite as a catalyst in a bench-scale downstream fixed bed reactor. The influence of steam to MSW ratios (S/M) on gas production and composition was studied at 900 °C over the S/M range of 0.39–1.04, for weight hourly space velocity (WHSV) in the range of 1.22–1.51 h −1. Over the ranges of experimental conditions examined, calcined dolomite revealed better catalytic performance at the presence of steam. H 2 and CO 2 contents increased with S/M increasing, while CO and CH 4 contents decreased sharply, the contents of CH 4, C 2H 4 and C 2H 6 were relatively small, and the influence of S/M was insignificant. The highest H 2 content of 53.22 mol %, the highest H 2 yield of 42.98 mol H 2/kg MSW, and the highest H 2 potential yield of 59.83 mol H 2/kg MSW were achieved at the highest S/M level of 1.04. Furthermore, there was a good agreement between the experimental gas composition and that corresponding to thermodynamic equilibrium data calculated using GasEq model. Consequently, a kinetic model was proposed for describing the variation of H 2 yield and carbon conversion efficiency with S/M during the catalytic steam gasification of MSW. The kinetic model revealed a good performance between experimental results and the kinetic model.

Physico-chemical changes in nano-silica and silica fume modified cement pastes in response to leaching

Leaching of calcium ions from cement pastes modified with silica fume and nano-silica, and the physico-chemical changes that this induces in the system are the focus of this paper. The pastes were subjected to slow (in deionised water) and accelerated (in 6M ammonium nitrate) leaching. Mass loss, increase in porosity and thermal analysis were used to quantify the physical and chemical changes in the system due to leaching. The modified cement pastes are found to exhibit better leaching resistance under both exposure conditions. It is shown that leaching in deionised water and cementing materials reaction are essentially coupled. When leached in ammonium nitrate, it is observed that the entire CH is leached from all the pastes, and pastes with very low initial CH contents suffer increased decalcification from C-S-H gel. It is shown that, when subjected to very aggressive leaching agents, a certain amount of CH acts as a buffer delaying C-S-H dissolution. The beneficial effect of nano-silica in controlling calcium ion leaching especially when subjected to accelerated leaching is brought out.

Experiments on chemical looping combustion of coal with a NiO based oxygen carrier

A chemical looping combustion process for coal using interconnected fluidized beds with inherent separation of CO 2 is proposed in this paper. The configuration comprises a high velocity fluidized bed as an air reactor, a cyclone, and a spout-fluid bed as a fuel reactor. The high velocity fluidized bed is directly connected to the spout-fluid bed through the cyclone. Gas composition of both fuel reactor and air reactor, carbon content of fly ash in the fuel reactor, carbon conversion efficiency and CO 2 capture efficiency were investigated experimentally. The results showed that coal gasification was the main factor which controlled the contents of CO and CH 4 concentrations in the flue gas of the fuel reactor, carbon conversion efficiency in the process of chemical looping combustion of coal with NiO-based oxygen carrier in the interconnected fluidized beds. Carbon conversion efficiency reached only 92.8% even when the fuel reactor temperature was high up to 970 °C. There was an inherent carbon loss in the process of chemical looping combustion of coal in the interconnected fluidized beds. The inherent carbon loss was due to an easy elutriation of fine char particles from the freeboard of the spout-fluid bed, which was inevitable in this kind of fluidized bed reactor. Further improvement of carbon conversion efficiency could be achieved by means of a circulation of fine particles elutriation into the spout-fluid bed or the high velocity fluidized bed. CO 2 capture efficiency reached to its equilibrium of 80% at the fuel reactor temperature of 960 °C. The inherent loss of CO 2 capture efficiency was due to bypassing of gases from the fuel reactor to the air reactor, and the product of residual char burnt with air in the air reactor. Further experiments should be performed for a relatively long-time period to investigate the effects of ash and sulfur in coal on the reactivity of nickel-based oxygen carrier in the continuous CLC reactor.

Rapid screening procedure to optimise the anaerobic codigestion of industrial biowastes and agricultural livestock wastes in Cyprus

Small-scale experimental investigations were undertaken on the anaerobic digestion (AD) and codigestion of livestock waste and industrial biowastes. A simple procedure was developed to rapidly determine the suitability of wastes for digestion. The experiment was split into two phases; initially, the seed (digested brewery waste) was replaced by the test waste over a period of 5 days. During the second phase, the test waste was incubated and monitored for methanogenesis. Dairy cattle slurry was the most efficient co-substrate which, when codigested with pig slurry in an equal ratio achieved volatile solids destruction of 32%, CH(4) production rate of 97.4 ml d(-1), maximum CH(4) content of 61.6% and total gas yield of 2229 ml after 529 h. High fat content wastes were unsuitable for AD due to low pH value and because the dominant microbial reaction was fermentation. Codigestion was investigated to overcome any inhibitions; however, dairy cattle slurry, abattoir wastewater and NaOH additions did not lead to methanogenesis. Treating these wastes by AD is feasible but without CH(4) production.

Phase transformations of a spray-dried iron catalyst for slurry Fischer–Tropsch synthesis during activation and reaction

The consecutive phase transformations of a precipitated spray-dried iron-based catalyst for slurry Fischer–Tropsch synthesis (FTS) during activation and reaction process were investigated using Mössbauer effect spectroscopy (MES). It was found that the fresh iron catalyst activation in situ using syngas resulted in the formation of a mixture of iron carbides and superparamagnetic (spm) phases. The relatively small size of fresh iron crystallites was an important factor in the formation of ε′-Fe 2.2C. During the reduction process, Fe 3+ (spm) phase was easier to be reduced than α-Fe 2O 3 phase. Fe 3O 4 was not an active phase for FTS. The transformation of α-Fe 2O 3 into Fe 3O 4 before carbides formation was necessary to obtain FTS activity of the iron catalyst. There was a correlation between the content of CH 4 in tail gas and the amount of iron carbides during activation. It was found that carbonization was the dominating phase transformation when the FTS reaction temperature increased from 250 °C to 270 °C. However, the oxidization was more remarkably at higher FTS reaction temperature. χ-Fe 5C 2 was the main iron phase at lower reaction temperature. The changes in the bulk compositions resulted in the variation in catalyst activity during FTS. The results of this study showed that the active phase for FTS was a mixture of carbides and corresponding amounts of superparamagnetic phase.

Long-term leaching test in concretes: An X-ray powder diffraction study

Long-term leaching tests on concretes have been performed to investigate portlandite dissolution by means of X-ray powder diffraction and the Rietveld method, which reveals a promising approach to detect CH content in leached concrete. Several concrete samples have been prepared and immersed in deionised water for 0, 35, 99 and 150 days. The results have been compared with those obtained by DTA/TGA measurements. The Rietveld method provides quantitative determinations of Ca(OH)2 in agreement with thermal analyses. Portlandite dissolution front in a concrete drifts inward upon increasing leaching duration. The distribution of portlandite as a function of the sample depth in the concretes treated for 0, 99 and 150 days show similar trends.

Analysis of acetylcholine, choline and butyrobetaine in human liver tissues by hydrophilic interaction liquid chromatography-tandem mass spectrometry

The strong polar quaternary ammoniums, acetylcholine (ACh), choline (Ch) and butyrobetaine (BB, (3-carboxypropyl)trimethylammonium), are believed playing important roles in liver metabolism. These metabolites are at low levels and are weakly retained on reversed-phase liquid chromatographic (RP-LC) columns. Several hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC–MS/MS) methods have been reported to analyze these compounds from different samples. However, no application to human liver tissues has been published. In this study, HILIC–MS/MS method was developed to simultaneously determine these three metabolites in human liver tissues. They were simply extracted from tissue, separated on a HILIC column, and detected by tandem MS in the mode of multiple reaction monitoring (MRM). Further studies on the recovery and repeatability based on real samples indicated the method was accurate and reliable. This method was successfully applied to measure the levels of ACh, Ch and BB in 61 human liver tissue samples including normal, hepatocellular carcinoma (HCC) and matched non-cancerous liver tissues. By comparison of Ch and ACh contents in 29 HCC with their matched non-cancerous liver tissues, it was found that ACh content increased in 11/29 HCC cases and decreased in 13/29 cases. Furthermore, the ACh/Ch ratio increased in 16/29 HCC cases, while it decreased in 8/29 cases. These results strongly indicated that there exist different patterns of ACh content in cancer tissues among HCC patients, thus highlighting the understanding of ACh and its relevant signal pathways in hepatic carcinogenesis and HCC progression.

Effects of turbulent diffusion on the chemistry of diffuse clouds

Aims. We probe the effect of turbulent diffusion on the chemistry at the interface between a cold neutral medium (CNM) cloudlet and the warm neutral medium (WNM). Methods. We perform moving grid, multifluid, 1D, hydrodynamical simulations with chemistry including thermal and chemical diffusion. The diffusion coefficients are enhanced to account for turbulent diffusion. We post-process the steady-states of our simulations with a crude model of radiative transfer to compute line profiles. Results. Turbulent diffusion spreads out the transition region between the CNM and the WNM. We find that the CNM slightly expands and heats up: its CH and H2 content decreases due to the lower density. The change of physical conditions and diffusive transport increase the H + content in the CNM which results in increased OH and H2O. Diffusion transports some CO out of the CNM. It also brings H2 into contact with the warm gas with enhanced production of CH + ,H + ,O H and H 2O at the interface. O lines are sensitive to the spread of the thermal profile in the intermediate region between the CNM and the WNM. Enhanced molecular content at the interface of the cloud broadens the molecular line profiles and helps exciting transitions of intermediate energy. The relative molecular yields are found higher for bigger clouds. Conclusions. Turbulent diffusion can be the source of additional molecular production and should be included in chemical models of the interstellar medium (ISM). It also is a good candidate for the interpretation of observational problems such as warm H2 ,C H + formation and presence of H + .

Geology and hydrogeochemistry of the Jungapeo CO 2-rich thermal springs, State of Michoacán, Mexico

We present the first geothermal assessment of the Jungapeo CO 2-rich mineral springs, which are located in the eastern part of Michoacán State (central Mexico) at the southern limit of the Trans-Mexican Volcanic Belt. All but one of the > 10 springs occur at the lower contact of the distal olivine-bearing basaltic andesite lavas of the Tuxpan shield, a 0.49- to 0.60-Ma-old cluster of monogenetic scoria cones and lava flows. The Tuxpan shield has a maximum radius of 6 km and was constructed on top of a folded and faulted Cretaceous basement consisting largely of marine limestones, marls, and shales. The mineral waters are characterized by moderate temperatures (28 to 32 °C), mild acidity (pH from 5.5 to 6.5), relatively high discharge rates, effervescence of CO 2 gas, clarity at emergence and abundant subsequent precipitation of hydrous iron, silica oxides, and carbonates around pool margins and issuing streamlets. Chemical and isotopic (deuterium, oxygen, and tritium) analyses of water and gas samples obtained during the period 1991–1997 indicate that the springs are largely composed of meteoric water from a local source with relatively short residence times (water ages of 7 to 25 years). Spring waters are chemically characterized by moderate SiO 2, Ca + Mg nearly equal to Na + K, high HCO 3, moderate to low Cl, low F and SO 4, high B, moderate Li, while Br and As are low. In contrast, Fe + Mn is exceptionally high. Thus, the Jungapeo waters cannot be regarded as high-temperature geothermal fluids. Instead, they resemble soda spring waters similar to other low-to-medium temperature soda waters in the world. Gas samples are extremely rich in CO 2 with no detectable geothermal H 2S or H 2 and very low contents of CH 4 and NH 3, indicating the gases are not derived from a high-temperature resource. Carbon-13 analyses of CO 2 show a narrow range (− 6.7‰ and − 7.2‰) that falls within the range for MORB CO 2. Thus, most CO 2 seems to originate from the mantle but some CO 2 could originate from thermal degradation of organic remains in underlying Cretaceous rocks. 3/4He ratios range from about 2 to 3 Rc/Ra, indicating that a small mantle/magmatic He component is present in the gases. In conclusion, the mineral waters are the surface expression of a low-temperature geothermal system of limited size that originates from the combined effects of a high regional heat flow and (possibly) the remnant heat released from subjacent basaltic andesite magma bodies that constitute the root zone of the Tuxpan shield.

Steam gasification of biomass for hydrogen-rich gas in a free-fall reactor

Characteristics of steam gasification of two kinds of biomass (legume straw and pine sawdust) at high heating rate (in the order of 1000 ∘ C s - 1 ) in a gas–solid concurrent downflow free-fall reactor were investigated. The effects of steam/biomass ( S / B ) mass ratio (0.0–1.0 g/g) and reactor temperature (750– 850 ∘ C ) on the product yields and the compositions of product gas were determined. The experimental results show that the gas yields and the content of H 2 in the gas increase with reactor temperature, while the yields of tar, char and the content of CO and CH 4 in the product gas decrease. The presence of steam increases the gas yields and reduces the tar and char yields. It is inferred that an in situ steam reforming reaction of tar takes place even in a short gas residence time in the free-fall reactor. Water–gas shift reaction determines greatly the gas compositions and H 2 production at higher temperature. The effects of different natural occurring catalysts, limestone, olivine and dolomite, were also investigated in the same unit. Dolomite reveals a comparably good performance in terms of catalytic activity of tar destruction and the consequential increase in the production of gases in thus a short vapor-catalyst contact time. The tars produced were analyzed by FTIR spectrometry. The results verify that the presence of steam and catalyst favors the tar decomposition.

Domain Formation in DODAB–Cholesterol Mixed Systems Monitored via Nile Red Anisotropy

The effect of the cholesterol (Ch) on liposomes composed of the cationic lipid dioctadecyldimethylammonium bromide (DODAB) was assessed by studying both the steady-state and time-resolved fluorescence anisotropy of the dye Nile Red. The information obtained combined with analysis of the steady-state emission and fluorescence lifetime of Nile Red (NR) for different cholesterol concentrations (5-50%) elucidated the presence of "condensed complexes" and cholesterol-rich domains in these mixed systems. The steady-state fluorescence spectra were decomposed into the sum of two lognormal emissions, emanating from two different states, and the effect of temperature on the anisotropy decay of Nile Red for different cholesterol concentrations was observed. At room temperature, the time-resolved anisotropy decays are indicative of NR being relatively immobile (manifest by a high r (infinity) value). At higher temperature, rotational times ca. 1 ns were obtained throughout and a trend in increasing hindrance was seen with increase of Ch content.

New insights into the structure and hydration of a stratum corneum lipid model membrane by neutron diffraction

The structure and hydration of a stratum corneum (SC) lipid model membrane composed of N-(alpha-hydroxyoctadecanoyl)-phytosphingosine (CER6)/cholesterol (Ch)/palmitic acid (PA)/cholesterol sulfate (ChS) were characterized by neutron diffraction. The neutron scattering length density across the SC lipid model membrane was calculated from measured diffraction peak intensities. The internal membrane structure and water distribution function across the bilayer were determined. The low hydration of the intermembrane space is a major feature of the SC lipid model membrane. The thickness of the water layer in the SC lipid model membrane is about 1 A at full hydration. For the composition 55% CER6/25% Ch/15% PA/5% ChS, in a partly dehydrated state (60% humidity) and at 32 degrees C, the lamellar repeat distance and the membrane thickness have the same value of 45.6 A . The hydrophobic region of the membrane has a thickness of 31.2 A . A decrease of the Ch content increases the membrane thickness. The water diffusion through the SC lipid model multilamellar membrane is a considerably slow process relative to that through phospholipid membranes. In excess water, the membrane hydration follows an exponential law with two characteristic times of 93 and 44 min. At 81 degrees C and 97% humidity, the membrane separates into two phases with repeat distances of 45.8 and 40.5 A . Possible conformations of CER6 molecules in the dry and hydrated multilayers are discussed.