Feed Reservoir Research Articles

Evaluation of Risk Factors for Peste des Petits Ruminants Virus in Sheep and Goats at the Wildlife-Livestock Interface in Punjab Province, Pakistan.

Peste des petits ruminants virus (PPRV) is causing infectious disease with high morbidity and mortality rate in domestic and wild small ruminants of Pakistan with valuable economical losses. The present study was carried out to investigate risk factors of PPRV in domestic small ruminants which were present in the vicinity of wildlife parks. A total of 265 sera samples (27 wild ruminants and 238 domesticated small ruminants) from apparently healthy animals from two different wildlife parks were collected and analysed for PPRV antibodies. Also, 20 nasal swabs from domestic small ruminants showing respiratory signs were collected to check for presence of PPRV antigen. Competitive ELISA revealed highest proportions of anti-PPRV antibodies in domestic small ruminants around the Wildlife Park at Lahore (35%) as compared to Faisalabad (13%), with no existence of PPRV antibodies in tested serum of wild ruminants at these parks. Higher seropositivity was observed in females (25.6%) than in males (5.1%) and in goats (34.5%) compared to sheep (11.2%). The results of N-gene based RT-PCR highlight the absence of PPRV due to lack of current PPR outbreak in the region during study period. Even though grazing was not a significant risk factor, there is still a possibility of wildlife-livestock interactions for feed and water reservoirs, resulting in spillover of PPR to wildlife. Keeping in view the high seropositivity and risk of PPR, vaccination should be adopted to avoid circulation of PPRV among wild and domestic small ruminants (sheep and goats).

Theoretical and experimental study of direct contact membrane distillation

Direct contact membrane distillation (DCMD) is characterized as a low-thermal energy process, involving evaporation and a phase change driven by the pressure difference between two fluid channels separated by a hydrophobic membrane. The temperature difference creates a driving pressure between the hot channel (feed) and the cold channel (permeate). This paper demonstrates the performance of the DCMD through high fidelity simulation and experimental observation to reveal a fundamental and qualitative understanding of the spatial distribution of the temperature, mass flux, and heat flux as well as the temperature polarization. The flow model is governed by the Navier–Stokes equations of non-isothermal fluid coupled with the energy equation for the two adjacent channel flow and the middle hydrophobic and porous membrane. The experimental study involved the development of a transparent acrylic DCMD unit operated by two peristaltic pumps where each cycles the feed and the permeate from the corresponding reservoir through the DCMD chambers that are separated by the PVDF–HFP membrane. The hot feed reservoir temperature is maintained at 40°C (4% salinity), whereas the permeate reservoir temperature is kept at 25°C (0% salinity). The system is tested using membranes of prescribed thickness, porosity, and conductivity. The model and experimental results were compared in counterflow configurations and a good agreement between the model and experimental was obtained for temperature distributions, mass flux, and temperature polarization coefficient (TPC). The system metrics were obtained for the DCMD showing a suitable TPC working range (0.3–0.55), a relatively low mass flux yield (5 kg/h m2) and a very low thermal efficiency (1.5%). These results suggest there is still a large potential in DCMD to enhance its overall yield in order to speed up their large-scale commercialization.

Biofouling and microbial communities in membrane distillation and reverse osmosis.

Membrane distillation (MD) is an emerging desalination technology that uses low-grade heat to drive water vapor across a microporous hydrophobic membrane. Currently, little is known about the biofilms that grow on MD membranes. In this study, we use estuarine water collected from Long Island Sound in a bench-scale direct contact MD system to investigate the initial stages of biofilm formation. For comparison, we studied biofilm formation in a bench-scale reverse osmosis (RO) system using the same feedwater. These two membrane desalination systems expose the natural microbial community to vastly different environmental conditions: high temperatures with no hydraulic pressure in MD and low temperature with hydraulic pressure in RO. Over the course of 4 days, we observed a steady decline in bacteria concentration (nearly 2 orders of magnitude) in the MD feed reservoir. Even with this drop in planktonic bacteria, significant biofilm formation was observed. Biofilm morphologies on MD and RO membranes were markedly different. MD membrane biofilms were heterogeneous and contained several colonies, while RO membrane biofilms, although thicker, were a homogeneous mat. Phylogenetic analysis using next-generation sequencing of 16S rDNA showed significant shifts in the microbial communities. Bacteria representing the orders Burkholderiales, Rhodobacterales, and Flavobacteriales were most abundant in the MD biofilms. On the basis of the results, we propose two different regimes for microbial community shifts and biofilm development in RO and MD systems.

Advanced centrifugal electrospinning setup

An advanced centrifugal electrospinning setup is proposed for the fabrication of non-woven textiles from polymer solutions using a pivotal feed unit and stationary collectors of large diameters and different designs: cylindrical collectors or collectors consisting of circularly arranged metal strips. The use of a collector composed of strips enables the production of aligned fibers. The feed reservoir is supplied with easy to handle interchangeable nozzles with the possibility of varing the nozzle-to-collector gap distance. The simultaneous use of four nozzles results in enhancement of the production rate and shortens the time for fabrication of a denser mat with a large surface area and enhanced exploitation properties. The special construction of the reservoir provides for its negligible dead volume.

The Weight of the World

The Weight of the World John Kinsella (bio) Red Shed 1 Who built our red barns so admired as emblems . . . —Hayden Carruth, "Marshall Washer" People hereabouts distinguish our placeby the massive red shed that pronouncesa ledge hacked into the hillside. Erectedby the previous owner, it yells culturalanomaly across the valley: I know howmuch she loved horses and dedicatedit as a stable, but I am not sure if she evervisited America and drew inspirationfrom the red barns of folklore and utility.After years living in red-barn mid-Ohio,we knew what red barns said to localsand visitors alike. Here and now, they say:sticks out like a sore thumb! Or: hey,you know the place, the one with the dirtygreat red shed! The air force uses it to sightfor bombing runs. Pure terror. In truthit's a placid red, though the horrorof hunkering down in bush, of wantingnot to be noticed, makes it anathema.Each day it holds sunlight betweenitself and an imaginary horizonthat curves with the hills overlookingthe greater Tooday valley. Imaginethe structure of what would have grownthere if the red shed hadn't stakeda claim? The runoff from its gentlypitched roof, the red music it makes [End Page 362] in high winds, bleeding arteriesthat feed reservoirs we drink from.This memory of America won't depart,and the red Colorbond steel that holdsa postcard portrait, the folklore that makes workand horses and a shelter for all weatherspeaks resistance: in the worst firesit will buckle and melt, but the sumof history, its loud declaration, remains. Red Shed 2 But let me tell you how it is inside those barns. —Hayden Carruth, "Marshall Washer" Steel red shed that inside looks like wooden stablesbecause of the amount of wood that is useful and willful, wooden framework masking metal with high eavesthat could have been turned into a loft but holds electrics, hay pitched and packed in a corner, and stalls,wooden and symmetrical and just communal enough, where mares are favored, the equipmentof horse-keeping a metaphor for being kept by horses. This is no longer a horse property, the whispersare of rodents and snakes, and to open the grand doors of the red shed is to wonder what to make of it, spiritsso imbued, no matter how skeptical you might be. Conjure no horses and no horse activities and nohusbandry of horses, washed and rubbed down [End Page 363] fresh from their workouts. Strange how you hearBeethoven's Ghost Trio at work on the senses, its hidden and never spoken air of horses, undertones and palpitationsof ghostly hormones. Last year I reviewed a performance of Equus. Last year one of my students did a pieceof creative autobiography on horses by horses. She knew how much she couldn't say. The Greek letters of horseshoesare still imprinted in the soft floor of the shed's theater, text colorless. What went on in there still goes on;deny it if possible. I wish this red shed were gone, hillside restored to its pristine apparitions of priornative vegetation holding and hiding animals that refuse to be shod, that refuse to envisagethe properties of a shed-stable, its cares and investments. Red Shed: "Psychological Depth" Red shed sealed for weeks but the dry—the dry compels me in, takes me by the noseand draws me to the pump, the compressor(more accurately) that will slug a two-strokepiston in its oily cage, its vacuum-makerand oxygenator, to spark and push airalong hoses far across the block, hundredsof meters to the boreheads, down pipes,down layers of Van Eyck oils, as if exhalationis a first-timer here, to puff into the aquiferand drive water up the contrary pipe,forcefeed the great tank, which is downto muddy leftovers. So turn to groundwater?All farms around us suck up any way they can, [End Page 364] draining and dragging the aquifer that will "neverempty," though we sense its cavity...

Dialysis shake flask for effective screening in fed-batch mode

In the traditional bioprocess development, the operation mode changes from batch in screening to fed-batch in lab and production scale. The presented dialysis shake flask allows small-scale fed-batch cultivations by a diffusion driven nutrient release. It consists of a feed reservoir system which is filled with a highly concentrated nutrient solution. The nutrient diffuses through a dialysis membrane into the medium. Cultivations with Escherichia coli BL21 (DE3) pRhotHi-2-EcFbFP and Hansenula polymorpha RB11 pC10-FMD (PFMD-GFP) proved the feasibility of the concept. As positive effects of these small-scale fed-batch cultivations, enhanced (up to 1000fold) yields for catabolite repressed product formation, reduced overflow metabolism and diminished medium acidification were observed. The new dialysis fed-batch shake flask is characterised by a high flexibility regarding the attainable feed rates and the spectrum of feedable compounds. The feed rate can be adjusted in a broad range by simply adapting the diffusion parameters. Based on the working principle, the release of any desired compound is possible. The dialysis fed-batch shake flask allows the detailed investigation of strains and process conditions under operation mode similar to industrial production process. Combined with the Respiration Activity Monitoring System (RAMOS), it represents an effective screening tool for the first steps of bioprocess development.

Performance of the Self-Breathing Air Direct Methanol Fuel Cell with Modified Poly (Vinylidene Fluoride) Grafted onto a Blended Polystyrene Sulfonated Acid (m-PVDF-g-PSSA) Membranes

This paper reports performance date for the direct methanol fuel cell (DMFC) with membrane electrode assemblies using modified poly (vinylidene fluoride) grafted the blended polystyrene sulfonated acid membranes (m-PVDF-g-PSSA) based on modified PVDF (poly vinylidene fluoride ) and the bended PSSA (polystyrene sulphonated acid). The membrane exhibited low methanol permeation coefficient, and good proton-conductivity. Furthermore, these materials have potentially lower methanol cross-over when compared to standard Nafion-type membranes. The membranes electrode assemblies were based on Nafion®-bonded carbon-supported catalyst: platinum/ruthenium for the anode and platinum for the cathode. The catalyst layer was coated directly on the treated membrane. To simulate the practical application, unit cell operates at room temperature and ambient pressure using liquid methanol and ambient air. A methanol solution is filled in the feed reservoir, and the cathode is exposed to ambient air. The cell performance of the self-breathing air DMFC, for short duration (<100h) testing, with the low cost membranes is superior to that of cells based on Nafion under identical operating conditions.

Nitrous oxide high purification by membrane gas separation

In this work the scope of nitrous oxide high purification by membrane gas separation was presented. The permeability values of nitrous oxide and its limiting impurities were measured for “Lestosil” membrane at feed pressure in the range from 100 to 400 kPa. The values of ideal selectivity were determined. It was shown that nitrous oxide is more permeable than impurities components. Therefore the process of nitrous oxide high purification was calculated for it carried out in membrane module with a feeding reservoir which is used for purification from low permeable impurities.

Optimization of water and air management systems for a passive direct methanol fuel cell

A multi-phase, multi-component, thermal and transient model is applied to simulate the operation of a passive direct methanol fuel cell and optimize the design. The model takes into consideration the thermal effects and the variation of methanol concentration at the feeding reservoir above the fuel cell. Polarization and constant current cases are numerically simulated and compared with experiments for liquid feed concentration, membrane thickness, water management and air management systems. Parameters considered when determining an optimal design include power density, fuel utilization and energy efficiencies and water balance coefficients. An optimal liquid feed concentration is determined to be 2.0 mol kg −1, which achieved a maximum power density of 21 mW cm −2 and a fuel utilization efficiency of 63.0%. An optimal design of a cell uses a thick membrane (Nafion 117) to reduce methanol crossover and two additional cathode GDLs to improve the water balance coefficient and efficiency of the cell. This combination results in a power density of 23.8 mW cm −2 and a water balance coefficient of −1.71. An air filter may also be added to improve the efficiency and water balance coefficient of the cell, however, a small loss in power density will also occur. Using an Oil Sorbents air filter the water balance coefficient is increased to −0.85, the fuel utilization efficiency is improved by 27.35% and the maximum power density decreased to 21.6 mW cm −2.

Mechanical intrusion models and their implications for the possibility of magma-driven swarms in NW Bohemia Region

Earthquake swarms are often assumed to be caused by magmatic or fluid intrusions, where the stress changes in the vicinity of the intrusion control the position, strength and rate of seismicity. Fracture mechanical models of natural intrusions or man-made hydrofractures pose constraints on orientation, magnitude, shape and growing rate of fractures and can be used to estimate stress changes in the vicinity of the intrusions. Although the idea of intrusion-induced seismicity is widely accepted, specific comparisons of seismicity patterns with fracture models of stress changes are rarely done. The goal of the study is to review patterns of intrusion-induced earthquake swarms in comparison to the observations of the swarm in NW Bohemia in 2000. We analyse and discuss the theoretical 3D shape of intrusions under mixed mode loading and apparent buoyancy. The aspect ratio and form of the intrusion is used to constrain parameters of the fluid, the surrounding rock and stress. We conclude that the 2000 NW Bohemia swarm could have been driven by a magmatic intrusion. The intrusion was, however, inclined to the maximal principal stress and caused shear displacement additional to opening. We estimate that the density diference between magma and rock was small. The feeding reservoir was possibly much larger than the area affected from earthquakes and may be a vertical dike beneath the swarm region.

Diffusion of iodide and iodate through Opalinus Clay: Monitoring of the redox state using an anion chromatographic technique

The through- and out-diffusion behaviour of 125I− and 125IO3- were separately studied in an intact sample of Opalinus Clay (OPA) from the Benken drilling site (Switzerland) using purified tracer solutions. The concentrations of the two radioactive I species, 125I− and 125IO3-, were monitored using a high performance anion exchange chromatographic technique. An effective diffusion coefficient, De = (4.5 ± 0.5) × 10−13 m2 s−1, and a rock capacity factor, α = 0.04 ± 0.01, were measured in the through-diffusion experiments with 125I−. The latter result shows that no sorption of I− takes place on OPA because in previous work the same rock capacity factor was measured for the non-sorbing Cl− tracer. The out-diffusion of 125I− was characterised by an unexpectedly high flux from the surface adjacent to the high concentration reservoir in the through-diffusion experiment. The present experiments resolved former inconsistencies with respect to the sorption of I− on OPA, where unpurified tracers were used. However, they confirmed the inconsistencies with respect to the observed De values between through- and out-diffusion experiments. No break-through of 125IO3- could be observed in the through-diffusion experiment with 125IO3- as the source species. Instead a flux of 125I− into the target reservoir was substantiated. This observation, together with the speciation analysis in the feed reservoir, showed that IO3- was rapidly converted to I− upon contact with OPA. The transformation was presumably mediated by unidentified reducing components of OPA because such fast reactions are not observed in homogeneous aqueous solutions. The rapid conversion of IO3- to I− in the OPA sample was corroborated in the profile analysis performed after the through-diffusion experiment, where a strongly one-sided distribution of the tracer ion was observed.

Production of biologically safe digested manure for land application by a full-scale biogas plant with heat-inactivation

Inactivation of indigenous indicator micro-organisms such as faecal coliforms, coliphages, and faecal streptococci was investigated in a full-scale biogas plant that mainly digested cow manure. The biogas plant consisted principally of a feed reservoir, fermentation tank (37 degrees C), heat-inactivation process (70 degrees C), and five reservoirs for the heat-inactivated, digested manure that was used by a local livestock farmer as liquid fertilizer. Although all the indicators tended to exhibit stepwise decreases with each stage of treatment, coliphages were found to be more capable of surviving than faecal coliforms and faecal streptococci under mesophilic anaerobic conditions as well as high temperature conditions (heat-inactivation at 70 degrees C). Liquid fertilizer produced at the biogas plant had faecal coliform densities less than the stipulations of the US EPA 40 CFR 503 Class A limits. Heat-inactivation tests indicated that although coliphages exhibited more tolerance than other bacterial indicators between 37 and 70 degrees C, they were more sensitive to continuous temperature increase than faecal coliforms and faecal streptococci.

A continuous-exchange cell-free protein synthesis system fabricated on a chip

Cell-free protein synthesis is now readily accepted as an alternative method for the preparation of protein molecules, especially where the simultaneous expression of multiple proteins is demanded. This technique provides a versatile platform for the rapid translation of genetic information into protein molecules within several hours. However, only a limited amount of protein can be produced from the conventional cell-free protein synthesis system of batch configuration due mainly to the rapid depletion of the key components, including energy sources and amino acids. In contrast, working on diffusion exchange of reaction components between the feeding reservoir and reaction chamber, the continuous-exchange cell-free (CECF)2 system enables extended protein synthesis and, thus, substantially enhances productivity. However, because the operation of the CECF reactor requires excessive amounts of reagents and specific setup, parallel operation of multiple CECF reactions cannot be readily conducted. In this study, as part of our efforts to develop a highly productive and expandable cell-free protein synthesis system in a cost-effective way, we have attempted to realize the scheme of CECF on a poly(dimethyl siloxane) (PDMS)-based chip. Copyright © 2007 Elsevier Inc. All rights reserved.

Volcano evolution and eruptive flux on the thick crust of the Andean Central Volcanic Zone: 40Ar/39Ar constraints from Volcan Parinacota, Chile

The 163 k.y. history as well as the chemi- cal and 46 km 3 volumetric evolution of Vol- can Parinacota are described in detail by new mapping, stratigraphy, and 57 40 Ar/ 39 Ar ages determined from groundmass or sani- dine crystals in basaltic andesitic to rhyolitic lavas. A more precise chronology of eruptions and associated eruptive volumes of this cen- tral Andean volcano, which was built upon 70-km-thick crust, provides a more com- plete view of how quickly volcanic edifi ces are built in this setting and how their mag- matic systems evolve during their lifetime. Development of the complex involved initial eruption of andesitic lava fl ows (163-117 ka) followed by a rhyodacite dome plateau (47- 40 ka) synchronous with the onset of the building of a stratocone (52-20 ka), which was later destroyed by a debris avalanche ~3 times larger than that at Mount St. Helens in 1980. Dome plateau emplacement occurred faster and later than has previously been published, implying a compressed duration of cone building and introducing a preced- ing 65 k.y. hiatus. Debris avalanche timing is refi ned here to be older than 10 but younger than 20 ka. Rapid postcollapse rebuilding of the volcanic edifi ce is delineated by 16 groundmass and whole-rock 40 Ar/ 39 Ar ages, which include some of the youngest lava fl ows dated by this method. Increase in cone- building rate and a continued trend toward more mafi c compositions following collapse imply an inter-relationship between the pres- ence of the edifi ce and fl ux of magma from the feeding reservoir. Cone-building rates at Parinacota are similar to those at other well- dated volcanoes on thinner crust; however, the distributed basaltic volcanism prevalent in those other arcs is virtually absent both at Parinacota and elsewhere in the Central Volcanic Zone. This suggests that while the hydrous, calc-alkaline magmas that make up the central volcanoes are not signifi cantly retarded by thick crust, primitive, dry basalts might be.

Fine gas purification to remove slightly penetrating impurities using a membrane module with a feed reservoir

Fine gas purification to remove slightly penetrating impurities using a membrane module with a feed reservoir

Viability study of different reverse osmosis membranes for application in the tertiary treatment of wastes from the tanning industry

The tanning industry uses large quantities of water and produces a correspondingly large amount of wastewater with high levels of salts and organic materials. Before these wastewaters can be eliminated, they must be submitted to a suitable depuration treatment. However, conventional treatments such as those used for urban wastewater are not able to reduce the salt content sufficiently and new methods need to be studied in the light of new technologies. In this aspect, membrane technology is increasingly used as a separation technique in chemical and environmental engineering, including desalination, selective separation and wastewater treatment. In this paper, we describe a comparative study of six different reverse osmosis membranes, which were tested for their ability to reduce the salt content in the tertiary treatment after the elimination of chromium salts and organic matter of an effluent from a pilot plant for treating industrial wastewater from the tanning industry to reach the legal levels established for their safe disposal. The membranes were checked using a 3×10 −3 m 2 flat cell, where the concentrated streams were recirculated to the feed reservoir.

Treatment of waters colored with methylene blue dye by vacuum membrane distillation

Textile industries consume large amounts of water and generate highly dye-contaminated effluents. Textile wastewaters have to be treated in order to be recycled in the process or to meet legislative requirements before being discharged. The objective of the present study was to examine the potential use of the vacuum membrane distillation process for the treatment of dyed solutions. Methylene blue (MB) was used as a model dye. Batch experiments were conducted on dilute MB-water mixtures using a tubular polypropylene membrane module. The concentration of MB dye within the feed reservoir was monitored over time. The impact of operating variables such as feed temperature, flow rate and initial dye concentration was investigated. A mathematical model incorporating temperature and concentration polarization effects was developed and validated on the experimental data.

Sulfur, heat, and magma budget of Erta ‘Ale lava lake, Ethiopia

We report here the first measurements of the SO 2 flux from Erta 'Ale volcano (Ethiopia); the measurements were obtained in March 2003 with a portable ultraviolet spectrometer. Emission rates averaged 0.7 kg.s - 1 from the active lava lake and 1.3 kg.s - 1 from the whole volcano (including fumarolic emissions in the north part of the caldera). This modest output combined with an estimate of the melt sulfur content indicates a magma-supply rate of 350-650 kg.s - 1 (∼0.13-0.25 m 3 .s - 1 ). Radiant heat power from the lava lake, measured by infrared thermography, was found to vary between ∼5 and 30 MW according to activity of the lake surface and time elapsed since resurfacing events. We show that 8%-14% crystallization and/or 30-60 °C cooling of the upwelling magma reaching the lake, as well as degassing, are sufficient to increase magma density in the upper conduit and drive convection between the surface and a feeding reservoir. Fluctuations in the system, such as degree of vesiculation and magma supply rate, can be buffered by ascent or descent of the magma level within a flared vent region whose geometry directly controls lake surface area and hence heat loss.

Application of reverse osmosis to reduce pollutants present in industrial wastewater

Reverse osmosis (RO) is increasingly used as a separation technique in chemical and environmental engineering; desalination, selective separation and wastewater treatment are well established examples. Treatment by RO reduces high levels of dissolved salts but has certain limitations in the removal of organics from chemical industry effluents. We describe a comparative study of four different polyamide membranes that were tested for their ability to reduce the concentrations of pollutants in a synthetic effluent stream containing acrylnitrile and three inorganic species (sulphate, ammonium and cyanide). The pH value of the solution plays an important role in the ionization of the different species and, subsequently, in their rejection. The membranes were checked using a 3×10 −3 m 2 flat cell where the permeated and concentrated currents were recirculated to the feed reservoir. In a preliminary set of experiments the pH of the feeding solution was 9.0. The rejection percentage of sulphate ion was high in all the membranes tested (96% to 99.4%) regardless of the working pressure. Ammonium rejection values were between 72.3% and 83.9%, while acrylnitrile rejection was low (10.5% to 28.8%) compared with the results obtained for the other pollutants. Cyanide rejection was negative for all membranes tested except for HR95PP, which produced a rejection percentage of 16.5%. The same membrane also produced higher rejection percentages for cyanide and acrylnitrile than the other membranes. Finally, this membrane was selected to study the influence of the feed stream pH on the rejection of ammonium and cyanide ions. The study concluded that cyanide and ammonium could not be acceptably eliminated in a single step operation when they are simultaneously present in industrial wastewater. The results pointed to the need to carry out several steps at different pH values to reduce the level of both pollutants in the studied wastewater.

Direct methanol fuel-cell combined with a small back-up battery

A description is given of a fuel-cell power-supply for mobile phones that operates at room temperature and ambient pressure using liquid methanol and ambient air. The unit is a hybrid system in which a direct methanol fuel-cell (DMFC) and a back-up battery are connected in parallel to meet the power requirements of mobile phones. Electrochemical catalysts for the anode and the cathode of the DMFC are synthesized and Nafion-115 is used as the electrolyte. A 2 M methanol solution is filled in the feed reservoir, and the cathode is exposed to ambient air. Eight unit cells, each having 9 cm 2 of active area, are connected in series in order to raise the output voltage to 2.5–3.9 V, which is the typical voltage range for most mobile phones. Also, to simulate the practical application, an electric circuit is included to increase the output voltage of the back-up battery to repeat the charge–discharge cycle. During talk mode, the DMFC supplies 10–50% of the required power and the back-up battery supplies the remainder. In standby mode, the DMFC covers 100% of the required power and charges the back-up battery.