Alkaline Phase Research Articles

Development of Creatine sensor based on antimony-doped tin oxide (ATO) nanoparticles

Low-dimensional antimony-doped tin oxide aggregated nanoparticles (ATO NPs; dia. ∼3.95nm) were synthesized using hydrothermal method in alkaline phase. The optical, morphological, and structural properties of ATO NPs were characterized in details using FT-IR, UV/vis., FESEM, XEDS, XPS, TEM and XRD techniques. Glassy carbon electrode (GCE) was fabricated with a thin-layer of aggregated ATO NPs by conducting coating binders (5% ethanolic nafion) for the development of selective and sensitive enzyme-less creatine sensors. Electrochemical responses along with higher sensitivity, large-dynamic range and long-term stability towards creatine were performed by electrochemical I–V approach. The calibration curve was found linear over a wide linear dynamic range (LDR) of creatine concentration (0.1nM∼1.0mM). From the gradient of the calibration plot, limit of detection (LOD) and sensitivity were calculated as 42.0±0.1pM and 276.3μAmM−1cm−2 respectively. It is an organized route for the development of non-enzymatic creatine sensor based on ATO NPs embedded GCE using electrochemical reduction phenomena and significantly applied for the real sample analyses. As far as we know, this report is the maiden publication on highly sensitive creatine sensor based on the ATO NPs/Nafion/GCE. This method could be a pioneer development in creatine sensitive sensor development using ATO NPs in reliable I–V method for the important sensor applications with useful doped nanomaterials coupled nano-technological system.

Characterization of the properties of perlite geopolymer pastes

This paper deals with the characterization of perlite-based geopolymer pastes, using fine perlite as raw material. The present study examined the effects of the main synthesis parameters such as perlite to activator ratio, NaOH concentration, the addition of soluble silica to the activator, and curing temperatureon the setting time, the stability in an aquatic environment, the viscosity of the paste, and the compressive strength of the solidified geopolymers. The results showed that these inorganic polymer pastes are non-Newtonian shear thinning fluids that achieve low viscosities at high shear stresses. The optimum synthesis conditions for the geopolymer pastes proved to be a) a low initial NaOH concentration in the alkaline phase (2–5 M) and b) a solid to liquid ratio of 1.2–1.4 g/mL. If very fast setting is necessary, the pastes should be prepared with a soluble silica-doped alkaline activating phase and cured at high temperatures around 90 °C.

U–Pb geochronology of bentonites from the Upper Cretaceous Kanguk Formation, Sverdrup Basin, Arctic Canada: constraints on sedimentation rates, biostratigraphic correlations and the late magmatic history of the High Arctic Large Igneous Province

AbstractU–Pb ages of zircon from bentonites within the upper Cretaceous Bastion Ridge and Kanguk formations, Sverdrup Basin, provide constraints on sedimentation rates, biostratigraphic correlations, timing of Oceanic Anoxic Event 2 (OAE2) in the High Arctic, and the late magmatic history of the High Arctic Large Igneous Province (HALIP). A late Cenomanian to early Turonian age for the base of the Kanguk Formation is confirmed that supports correlations of the global OAE2 in the High Arctic. Sedimentation rates varied from 19 m Ma−1between 93 and 91 Ma to 26 m Ma−1between 91 and 83 Ma at Axel Heiberg Island. At Ellef Ringnes Island, the lower Kanguk Formation records high rates of ~70 m Ma−1between 94 and 93 Ma, which decrease to rates comparable to those of the upper Axel Heiberg section. Differences in sedimentation rates may reflect differences in setting prior to the major transgression in the latest Cenomanian to early Turonian. The timing of Arctic occurrences of theScaphites nigricollensisandScaphites depressusammonite zones is shown to be broadly comparable to that of lower-latitude occurrences within the Western Interior Seaway. An eruption frequency of 0.5–2.5 Ma characterizes the late alkaline phase of HALIP magmatism. Volcanic bed thicknesses of 10–50 cm suggest ash transport distances of less than 1000 km. Long-lived volcanic centres, in the area of the Alpha Ridge, northern Ellesmere Island or northern Greenland, were the likely source of volcanic ash over a period of 10–15 Ma.

Mass Transfer and Hydrodynamic Aspects of Kinetics Studies in Light Oil Sweetening: A Review

AbstractLPG (liquid petroleum gas) sweetening is a very important refining process in which mercaptans are extracted from LPG by caustic solution, resulting in mercaptide salts. Subsequently, these mercaptides are oxidized in the presence of air and catalyst to disulphides involving gas liquid (G‐L) reactions in an oxidizer. This review discusses design and operational aspects of a laboratory G‐L oxidizer which are essential for determination of intrinsic kinetic parameters of the mercaptide oxidation step. These kinetic parameters are subsequently used for scale‐up and design of grass root industrial scale oxidizers. The sweetening is categorized as a slow reaction. Hence, reaction takes place both in the film and the bulk. Transport of oxygen across the air to the aqueous alkaline phase in the oxidizer is critical and controlled by the liquid film mass transport term. Thus, oxygen transportation limitations need to be overcome and ensured before conducting kinetic studies. This paper fills the gap between laboratory reactor design and operational aspects by presenting a detailed review on chemical engineering analysis for maximization of the volumetric mass transfer coefficient using operational aspects of an agitated sparged G‐L reactor.

Purple Staining of Archaeological Human Bone: An Investigation of Probable Cause and Implications for Other Tissues and Artifacts

Excavations in the 1990s at the medieval Chapter House of Worcester Cathedral, UK, revealed medieval human skeletal remains, some of which exhibited a distinctive purple coloration. The nature of the colored bone was investigated using solvents for stain extraction, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray fluorescence (XRF), plane polarized (PPL) and cross-polarized (XPL) light microscopy, and auto fluorescence (AF) microscopy. Normal bone from the cemetery was used as a control. The color does not arise from a stain soluble in normal organic solvents. EDX and XRD analysis showed no significant difference between purple and normal bone. XRF analysis shows the presence of trace levels of iron, manganese, zinc, and copper in the affected material. This exhibited a pink color in acid phase and a blue color in alkaline phase. These two states were reversible. The alkaline phase gradually changed irreversibly to yellow over time. These data suggest that the coloration is consistent with the presence of high levels of purple acid phosphatase (PAP) enzyme. The presence of trace amounts of iron, manganese, zinc, and copper suggests a plant or fungal origin for the putative PAP, possibly a member of theAspergillus ficuumspecies.

Non-enzymatic simultaneous detection of l-glutamic acid and uric acid using mesoporous Co3O4 nanosheets

Co3O4 nanosheets were synthesized by wet chemical technique at low-temperature in alkaline phase.

Geochemistry and petrogenesis of mafic–ultramafic suites of the Irindina Province, Northern Territory, Australia: Implications for the Neoproterozoic to Devonian evolution of central Australia

Petrological and geochemical data for magmatic mafic–ultramafic suites of the Irindina and Aileron provinces of the Eastern Arunta region, Northern Territory, Australia constrain the petrogenesis and tectonic setting of magmatic events covering ~500millionyears. Six geochemically distinct magmatic suites, here named A–F, have been identified and provide evidence of the tectonic history of this region and also are linked to two mineralisation-related magmatic events: the Lloyd Gabbro (Ni–Cu–PGE mineralisation) and the Riddoch Amphibolite (Cyprus-style Cu–Co volcanogenic massive sulphide mineralisation).The whole-rock geochemistry of Suites A and F is indicative of melts derived from a range of mantle depths (garnet to spinel lherzolite) and source enrichment. Suite D is likely related to the ~1070Ma Warakurna/Giles event of central Australia, including the Alcurra (Musgrave) and Stuart (Arunta) dyke swarms, and likely formed through either: a) melting of subduction modified, sub-continental lithospheric mantle (SCLM) by an upwelling mantle plume; or b) a combination of intra-plate tectonic processes involving a long-lived thermal anomaly, lithospheric-scale architecture that focussed magmatism, and large-scale tectonism. Suite F represents more alkaline magmas, derived from a deeper source, but most likely formed during the same Warakurna LIP event (possibly contemporaneously) as Suite D. Suite E (the Riddoch Amphibolite) was most likely emplaced in a back-arc basin (BAB) setting at ~600Ma, coincident with Delamerian subduction and BAB formation along the eastern Proterozoic margin of Australia from Queensland to the eastern Arunta and possibly further south. Subsequent destabilisation of the SCLM underneath the North Australian Craton generated the ~510Ma Kalkarindji LIP in the form of Suite B intrusions that assimilated some of the older Suite E (Riddoch) material. This event is locally known as the ~506Ma Stanovos Igneous Suite and represents the most voluminous magmatic event within the study area. Suite A samples are more alkaline and cannot be correlated with any known magmatic events; however, they probably represent an unidentified alkaline phase of the Kalkarindji LIP event derived from a deep mantle source region. This suite is similar to the more widespread Kalkarindji and Suite B/Stanovos magmas in that these magmas assimilated arc material (i.e., Suite D) prior to emplacement. The last magmatic event occurred during the exhumation and inversion of the Irindina basin during the 450–300Ma Alice Springs Orogeny, resulting in the formation of melts derived from a deep mantle source. These melts subsequently became contaminated en route to emplacement as the ~409Ma Suite C Lloyd Gabbro.

Synergistic effect of the parameters affecting wet flue gas desulfurization using magnesium oxides by-products

Abstract A previous study carried out by the authors allowed to identify the optimum MgO by-product for a 100% SO 2 removal efficiency in a wet flue gas desulfurization (FGD) process. The present research analyzes the synergistic effect between the main parameters affecting the proposed desulfurization process. The design of experiments (DoE) was used as statistical tool for evaluating the influence of the solid-to-water ratio ( S / W ), water ( W ) and time of reaction ( t R ) over the most important responses of the FGD process: Mg 2+ , Ca 2+ and SO 4 2− in solution, pH and conductivity ( k ), and time of saturation ( t S ). According to the analysis performed, the results of Mg 2+ and Ca 2+ leaching showed the greater effect of Mg compounds. The production of SO 4 2− was simultaneously affected by S / W and W , due to the mass-transfer nature of the process. The pH range was found to be controlled by the solubility product of the alkaline phases while k showed a linear dependency on the dissolution of the solid and SO 2 absorption. As for desulfurization efficiency, two behaviors were observed by the combined effect of the factors: low S / W ratios in the whole W range showed that adding more solid had a positive effect as it increased t S while higher ratios decreased it. Hence, an optimum S and W consumption for 100% removal efficiency can be estimated in sake of saving energy, W and by-product. The present research methodology could be extended to other by-products for wet FGD as the current EU legislation is driving the industry to the reutilization of wastes and residues.

Structural and magnetic property studies on low temperature chemically synthesised one-dimensional Zn1−xNixO nanorods

One-dimensional Zn1−xNixO nanorods have been established through a facile surfactant/template free low temperature hydrothermal route, which involves the direct growth of the nanorod-like structures from an aqueous alkaline phase. The monophasic wurtzite structure of the Ni-doped ZnO nanocrystallites were initially studied using the X-ray diffractograms and their rod-like morphological appearance and homogeneity were analyzed through the aid of electron microscopes. Moreover, the substitution of Ni ions was found to contain the oxygen related vacancies and defect states in the nanostructures, through suppressing the E2(high) and E1(LO) modes in the Raman spectra. A similar trend was also observed in the subband gap emission, over the visible region of the emission spectra. The magnetic property studies on the Zn1−xNixO semiconducting nanorods revealed the presence of paramagnetic characteristics at room temperature and antiferromagnetic interactions at 20 K.

Detection of Micrococcus luteus biofilm formation in microfluidic environments by pH measurement using an ion-sensitive field-effect transistor.

Biofilm formation in microfluidic channels is difficult to detect because sampling volumes are too small for conventional turbidity measurements. To detect biofilm formation, we used an ion-sensitive field-effect transistor (ISFET) measurement system to measure pH changes in small volumes of bacterial suspension. Cells of Micrococcus luteus (M. luteus) were cultured in polystyrene (PS) microtubes and polymethylmethacrylate (PMMA)-based microfluidic channels laminated with polyvinylidene chloride. In microtubes, concentrations of bacteria and pH in the suspension were analyzed by measuring turbidity and using an ISFET sensor, respectively. In microfluidic channels containing 20 μL of bacterial suspension, we measured pH changes using the ISFET sensor and monitored biofilm formation using a microscope. We detected acidification and alkalinization phases of M. luteus from the ISFET sensor signals in both microtubes and microfluidic channels. In the alkalinization phase, after 2 day culture, dense biofilm formation was observed at the bottom of the microfluidic channels. In this study, we used an ISFET sensor to detect biofilm formation in clinical and industrial microfluidic environments by detecting alkalinization of the culture medium.

Superoxide Triggers an Acid Burst in Saccharomyces cerevisiae to Condition the Environment of Glucose-starved Cells

Although yeast cells grown in abundant glucose tend to acidify their extracellular environment, they raise the pH of the environment when starved for glucose or when grown strictly with non-fermentable carbon sources. Following prolonged periods in this alkaline phase, Saccharomyces cerevisiae cells will switch to producing acid. The mechanisms and rationale for this "acid burst" were unknown. Herein we provide strong evidence for the role of mitochondrial superoxide in initiating the acid burst. Yeast mutants lacking the mitochondrial matrix superoxide dismutase (SOD2) enzyme, but not the cytosolic Cu,Zn-SOD1 enzyme, exhibited marked acceleration in production of acid on non-fermentable carbon sources. Acid production is also dramatically enhanced by the superoxide-producing agent, paraquat. Conversely, the acid burst is eliminated by boosting cellular levels of Mn-antioxidant mimics of SOD. We demonstrate that the acid burst is dependent on the mitochondrial aldehyde dehydrogenase Ald4p. Our data are consistent with a model in which mitochondrial superoxide damage to Fe-S enzymes in the tricarboxylic acid (TCA) cycle leads to acetate buildup by Ald4p. The resultant expulsion of acetate into the extracellular environment can provide a new carbon source to glucose-starved cells and enhance growth of yeast. By triggering production of organic acids, mitochondrial superoxide has the potential to promote cell population growth under nutrient depravation stress.

Detection of aprepitant drug based on low-dimensional un-doped iron oxide nanoparticles prepared by a solution method

We have prepared as-grown iron oxide nanoparticle by a solution method using reducing agents (urea and NH4OH) in alkaline phase. The nanoparticles were characterized by UV/vis, FT-IR, and Raman spectroscopy, powder X-ray diffraction, and field-emission scanning electron microscopy. They were deposited on a glassy carbon electrode (GCE, surface area, 0.0316cm2) to give a sensor with a fast response towards Aprepitant (APPT) drug in buffer phase. The sensor also exhibits good sensitivity and long-term stability as well as enhanced electrochemical response. The calibration plot is linear (r2=0.9703) over the 2.2nM to 4.1μM APPT concentration range. The sensitivity is ∼2.5316±0.5μAcm−2mM−1, and the detection limit is 0.38±0.02nM (at a signal-to-noise-ratio of 3) in short response time (10s). This method could also be employed for the determination of drugs in quality control of formulation using a reliable I–V method.

Separation of norbixin fromBixa orellanaseed raw dye by Aliquat-336

The reactive extraction of Bixa orellana seed pigment norbixin with cationic carrier Aliquat-336 (QCl) in a two phase system has been studied. A raw alkali extract of Bixa orellana pigments in 0.5% sodium hydroxide solution is used as aqueous phase and Aliquat-336 dissolved in hexane as solvent is used as the organic phase. In the aqueous alkaline phase, the pigment (bixin + norbixin) exists as sodium norbixinate in ionized form. This sodium norbixinate forms complex with QCl by an ion-exchange mechanism which is pH dependent. Re-extraction occurs via another ion-exchange reaction with H+ ion with another aqueous phase of low pH. Complexation expressed as degree of extraction increases with pH reaching almost an asymptotic whereafter tends to decrease slightly. Around 99% recovery of norbixin as its complex with Aliquat-336 was achieved at an organic phase to aqueous phase volume ratio 2:1. 98% of the norbixin-QCl complex was recovered as norbixin in aqueous solution at pH 4. The results of this investigation may be considered reasonable to believe that reactive extraction is likely to provide an attractive and alternative separation method for the recovery of norbixin. © 2011 American Institute of Chemical Engineers Environ Prog, 32: 134–138, 2013.

Magmatism and Eurekan deformation in the High Arctic Large Igneous Province: 40Ar–39Ar age of Kap Washington Group volcanics, North Greenland

The High Arctic Large Igneous Province is unusual on two counts: first, magmatism was prolonged and has been suggested to include an initial tholeiitic phase (130–80Ma) and a second alkaline phase (85–60Ma); second, it was subsequently deformed during the Eurekan Orogeny. New 40Ar–39Ar dating of alkaline volcanics from Kap Kane, part of the Kap Washington Group volcanics at the northern tip of Greenland, provides an emplacement age of 71.2±0.5Ma obtained from amphibole in lapilli tuffs, and a thermal resetting age of 49–47Ma obtained in feldspar and whole-rocks from trachyte flows. Patch perthite feldspars and coeval resetting of Rb–Sr isotopes by hydrothermal fluids provide further support for thermal overprinting. This thermal event is interpreted as a result of compressional tectonism of the Kap Cannon Thrust Zone in which older Palaeozoic metasediments were thrusted northwards over the Kap Washington Group volcanics.The formation of the tholeiitic suite (130–80Ma) is linked to the opening of the Canada Basin and may involve mantle plume action. Formation of the alkaline suite (85–60Ma) is attributed to continental rifting in the Lincoln Sea area linked to seafloor spreading in the Labrador Sea and the Baffin Bay, and to eastwards displacement of Greenland relative to North America. The alkaline suite, therefore, may be unrelated to the main tholeiitic phase of the High Arctic Large Igneous Province. The subsequent initiation of continental rifting and ensuing seafloor spreading in the Northeast Atlantic resulted in spreading and volcanism (61–25Ma) on both sides of Greenland, pushing Greenland northwards relative to North America. The tectonic setting in the High Arctic thus changed from extensional to compressional and volcanic activity was terminated. Evaluation of plate kinematic models shows that the relative northwards movement of Greenland culminated in the Eocene, coinciding with thermal resetting. We conclude that compression in North Greenland peaked at 49–47Ma and coincided with the Eurekan Orogeny in a belt across the Canadian Arctic Islands and western Svalbard.

Processing of Human Feces Using Beanstalk and Sawdust as Matrix in a Composting-Type Eco-Toilet

This study aims to investigate the changing of operational parameters and waste reducing rate, as well as the possibility of using produced composts as organic fertilizer in an on-site composting-type eco-toilet filled with mixed materials of beanstalk and sawdust as reaction matrix. During the 23-week period, change of pH was divided into three phases: acid phase (6.63-7.00), alkaline phase (9.00-9.71) and stable phase (8.10-9.00). With continuous input of feces and urine, total nitrogen, total phosphorus and total potassium contents was increased to reach 4.3%, 1.06% and 2.03%, respectively. Organic matter content decreased from 95.6% to 76.2% and the total reduction rate of dry weight increased gradually from 46.93% to 92.29%. The composts could be used as organic fertilizer at suitable concentrations. The suitable concentration for cucumber, cabbage and rape growth was obtained to be at compost ratios of 1:15-1:30, 1:15-1:20 and 1:25-1:40, respectively. Microbial utilization efficiency of human feces and urine could be improved when the mixed material of beanstalk and sawdust was used as reaction matrix in an on-sit composting-type eco-toilet. The mixed materials with beanstalk and sawdust at a volume ratio of 1:1 was found to be efficient to transform human feces and urine into organic fertilizer rich in the elements of N, P and K.

Geochronology of Mount Morning, Antarctica: two-phase evolution of a long-lived trachyte-basanite-phonolite eruptive center

Mount Morning is a Cenozoic, alkaline eruptive center in the south-west Ross Sea, Antarctica. New ages on 17 Mount Morning volcanic rocks (combined with 34 existing ages) allows division of Mount Morning volcanism into two phases, erupted between at least 18.7 Ma and 11.4 Ma, and 6.13 and 0.02 Ma. The position of Mount Morning on the active West Antarctic Rift System within the stationary Antarctic plate is a key factor in the eruptive center’s longevity. The earliest, mildly alkaline, Phase I volcanism comprises predominantly trachytic rocks produced by combined assimilation and fractional crystallization processes over 7.3 m.y. Strongly alkaline Phase II volcanism is dominated by a basanite – phonolite lineage, with the youngest (post last glacial maximum) activity dominated by small volume primitive basanite eruptions. The evolution from mildly to strongly alkaline chemistry between phases reflects magma residence time in the crust, the degree of mantle melting, or the degree of magma—country-rock interaction. Phase I magmatism occurred over a comparable area to the present-day, Phase II shield. The 5.2 m.y. volcanic hiatus separating Phase I and II coincides with a cycle of eruption and glacial erosion at the nearby Minna Bluff eruptive center. Mount Morning is the likely source of volcanic detritus in Cape Roberts drill-core (about 24.1 to 18.4 Ma) and in ANDRILL drill-hole 1B (about 13.6 Ma), located 170 km north and 105 km north-east respectively, of Mount Morning. Based upon the timing of eruptions and high heat-flow, Mount Morning should be considered a dormant volcano.

Transient Receptor Potential Vanilloid Subtypei1 (TRPV1) Expression in Bone Marrow-derived Stromal Cells of Rats in vitro

We studied rat femur bone marrow stroma cells (BMSCs) and microenvironment turnover in capsaicin (CAP)-conditioned media in vitro. Proliferation, differentiation and TRPV1 expression at the mRNA level (RT-PCR) of conditioned BMSCs, and pH changes and calcium assay of the conditioned culture media were examined; the obtained data were statistically analyzed. Elapsed time-dependent cell proliferation of BMSCs peaking at day 10 was observed in alkaline phase and 37℃ microenvironment. Although there were no significant differences of proliferation in different conditions on designated experimental days, day 10 was the turning point of proliferation phase where intermittent administration of 25µm CAP resulted in the least amount of cell proliferation than other culture conditions on day 14. The present RT-PCR study revealed expression of TRPV1 mRNA during 3 to 4 days (either day 3 or day 7) after single or intermittent exposure under 25µM CAP. This study elucidated that by intermittent addition of 25µM CAP into the culture medium, the CAP-sensing TRPV1 of the rat BMSCs was activated to significantly mediate Ca (superscript 2+) influx leading to cell death, and the TRPV1 was desensitized, between day 7 and day 10 in vitro.

Evaluation of the uncertainty statement in the case of mercury speciation analysis

Nowadays, the evaluation of the uncertainty statement is more and more incorporated into quality assurance procedures. In this paper, the uncertainty statement of a mercury speciation analytical method is presented using the relationships fixed by GUM (Guide to the Expression of Uncertainty in Measurement). According to the developed analytical method, the sample is digested using an alkaline phase, then phenylation is applied to derivatize the organomercury compounds found in the digested solution. Finally, following solid phase microextraction (SPME) of the phenylated species, detection with GC-AFS is carried out. The main purpose of this work is to identify the analytical steps that have the strongest influence on the reproducibility of the measurements. The presented approach is based on an investigation executed in more steps and so it provides an opportunity to determine the uncertainty of each applied analytical step. Based on the completed experiments, the alkaline digestion and the calibration were the most critical steps regarding reproducibility. Phenylation derivatization, SPME and volume and weight measurements during sample preparation were less dominant processes in this respect.

Bio-geochemical behavior of90Sr and137Cs in tropical soil

In this work TF values for 90 Sr and 137 Cs were measured for reference plants grown in lysimeters containing soils representative of large agricultural areas in Brazil: Ferralsol, Nitisol and Acrisol. These results were discussed in the light of pedological analyses and results from the follow sequential chemical extraction protocol: 1) slightly acidic phase containing readily bioavailable elements; 2) easily reducible phase containing elements bound to Mn oxides; 3) oxidizable phase containing elements bound to labile organic matter; 4) alkaline phase containing mainly elements bound to Fe compounds; 5) resistant phase not potentially available to crops. These results showed that the main soil factors influencing the 137 Cs transfer to these soils were: exchangeable K, organic matter and iron oxides content. These results showed that 90 Sr plant uptake was influenced by exchangeable Ca. All these finds are in accord with previous studies and seems confirm the vulnerability of Ferralsol and Acrisol to 137 Cs contamination

Human Rhesus-associated glycoprotein mediates facilitated transport of NH(3) into red blood cells.

Rhesus (Rh) antigens are carried by a membrane complex that includes Rh proteins (D and CcEe), Rh-associated glycoproteins (RhAG), and accessory chains (LW and CD47) associated by noncovalent bonds. In heterologous expression systems, RhAG and its kidney orthologs function as ammonium transporters. In red blood cells (RBCs), it is generally accepted that NH(3) permeates by membrane lipid diffusion. We have revisited these issues by studying RBC and ghosts from human and mouse genetic variants with defects of proteins that comprise the Rh complex. In both normal and mutant cells, stopped-flow analyses of intracellular pH changes in the presence of inwardly directed methylammonium (CH(3)NH(+)(3)+CH(3)NH(2)) or ammonium (NH(+)(4)+NH(3)) gradients showed a rapid alkalinization phase. Cells from human and mouse variants exhibited a decrease in their kinetic rate constants that was strictly correlated to the degree of reduction of their RhAG/Rhag expression level. Rate constants were not affected by a reduction of Rh, CD47, or LW. CH(3)NH(2)/NH(3) transport was characterized by (i) a sensitivity to mercurials that is reversible by 2-mercaptoethanol and (ii) a reduction of alkalinization rate constants after bromelain digestion, which cleaves RhAG. The results show that RhAG facilitates CH(3)NH(2)/NH(3) movement across the RBC membrane and represents a potential example of a gas channel in mammalian cells. In RBCs, RhAG may transport NH(3) to detoxifying organs, like kidney and liver, and together with nonerythroid tissue orthologs may contribute to the regulation of the systemic acid-base balance.