Cent Carbon Dioxide Research Articles

How to grow concrete

Concrete is the most widely used man-made material, and second only to water as the most-consumed resource on Earth. Incredibly, 7.3 billion cubic metres of concrete is poured every year, accounting for 8 per cent of carbon dioxide emissions.While greener concrete may help curb some of the environmental damage done by our favourite building material, we will probably need even more of it. After all, our growing global population, which is expected to top 9.7 billion by 2050, will need new homes and we will need efficient ways to maintain current houses and infrastructure too.

Making fuel and oxygen on Mars using plasma

Future colonists on Mars could use plasma technology to make their own oxygen. The atmosphere on Mars is 96 per cent carbon dioxide, says Vasco Guerra at the University of Lisbon in Portugal. This can be split to extract breathable oxygen and carbon monoxide, a fuel that could give us a gas station on the Red Planet, he says. He and his team calculate that creating a carbon dioxide plasma--a mush of ions made by passing an electric current through a gas--could split carbon dioxide from oxygen more easily on Mars than on Earth.

Heterogeneous chemistry in the atmosphere of Mars

Hydrogen radicals are produced in the martian atmosphere by the photolysis of water vapour and subsequently initiate catalytic cycles that recycle carbon dioxide from its photolysis product carbon monoxide. These processes provide a qualitative explanation for the stability of the atmosphere of Mars, which contains 95 per cent carbon dioxide. Balancing carbon dioxide production and loss based on our current understanding of the gas-phase chemistry in the martian atmosphere has, however, proven to be difficult. Interactions between gaseous chemical species and ice cloud particles have been shown to be key factors in the loss of polar ozone observed in the Earth's stratosphere, and may significantly perturb the chemistry of the Earth's upper troposphere. Water-ice clouds are also commonly observed in the atmosphere of Mars and it has been suggested previously that heterogeneous chemistry could have an important impact on the composition of the martian atmosphere. Here we use a state-of-the-art general circulation model together with new observations of the martian ozone layer to show that model simulations that include chemical reactions occurring on ice clouds lead to much improved quantitative agreement with observed martian ozone levels in comparison with model simulations based on gas-phase chemistry alone. Ozone is readily destroyed by hydrogen radicals and is therefore a sensitive tracer of the chemistry that regulates the atmosphere of Mars. Our results suggest that heterogeneous chemistry on ice clouds plays an important role in controlling the stability and composition of the martian atmosphere.

Antimicrobial resistance of Campylobacter jejuni and C coli isolates in Japan

Campylobacter jejuni and Campylobacter coli are foodborne enteric pathogens of human beings (Allos 2001), with poultry meat being a major source of Campylobacter infection (Park 2002). Recently, increasing levels of resistance in C jejuni and C coli to macrolide and fluoroquinolone antibiotics have become a worldwide problem as these are the therapeutic agents used for Campylobacter infections in humans (Aarestrup and Engberg 2001). The aims of this study were to investigate the antimicrobial resistance of Campylobacter isolates from human beings and poultry meat in Kanagawa, Japan, and to detect point mutations related to macrolide and quinolone resistance by using a line probe assay (MQ-LiPA), designed for the rapid and easy simultaneous detection of macrolide resistance mutations in 23S rDNA and quinolone resistance mutations in gyrA (Niwa and others 2003). In total, 249 isolates were used in this study: 193 human Campylobacter strains and 56 poultry meat strains were isolated in Kanagawa prefecture from 1979 to 2001 and from 1997 to 2000, respectively, and identified by biological and biochemical tests in the Kanagawa Prefectural Public Health Laboratory. All strains were cultured on Mueller-Hinton (MH) agar plates (Oxoid) at 42°C under microaerobic conditions (85 per cent nitrogen, 5 per cent oxygen, 10 per cent carbon dioxide) for 24 hours. The following antimicrobial agents were tested: nalidixic acid (Sigma), ofloxacin (Sigma), erythromycin (Sigma), tetracycline (Wako), ampicillin (Sigma), gentamicin (Sigma) and phosphomycin (Wako). Minimum inhibitory concentrations (MICs) were determined by an agar dilution method using MH agar plates. All MIC plates were inoculated with approximately 104 colony-forming units of each strain per spot using a multipoint inoculator. A control plate without antibiotics was also incubated at the end of each procedure. The plates were incubated for 24 hours at 42°C under microaerobic conditions. The MIC was defined as the lowest concentration producing no visible growth. The breakpoints were used according to the recommendations of the National Committee for Clinical Laboratory Standards (NCCLS 2002) except for ofloxacin and phosphomycin. No criteria were shown for ofloxacin or phosphomycin in the NCCLS document, so a breakpoint of 8 mg/litre was used for ofloxacin (Sanchez and others 1994) and 128 mg/litre for phosphomycin (Gomez-Garces and others 1995). The line probe assay (MQ-LiPA) was performed by the method described by Niwa and others (2003). This method is based on PCR and reverse hybridisation to a number of oligonucleotide probes immobilised as parallel lines on a nylon membrane strip. Oligonucleotide probes were tailed with dTTP (Gibco BRL). Poly (dT)-tailed probes and biotinylated DNA used as a colour development control were immobilised as parallel lines on the nylon membrane strip by ultraviolet exposure. The PCR was performed using primers designed according to the sequences of 23S rDNA and gyrA. The results of the antimicrobial susceptibility tests for the C jejuni and C coli isolates are shown in Table 1. In human isolates, the frequency of strains resistant to the quinolones, nalidixic acid and ofloxacin, increased remarkably, while tetracycline-resistant strains decreased during the study periods 1979 to 1989 and 1990 to 2001. Quinolone-resistant Campylobacter strains were observed from 1977 in both human and poultry meat isolates in this study. In Japan, many kinds of fluoroquinolones were introduced from the second half of the 1980s and the first half of the 1990s in the medical and veterinary fields, respectively. Poultry meat is a main source of Campylobacter infection in Japan (Ono and Yamamoto 1999) and various other countries (Padungton and Kaneene 2003), and the increase in the incidence of fluoroquinolone resistance in human isolates appears to be related to that in poultry. There was a marked decrease in erythromycin-resistant strains in human C jejuni isolates between the two study periods (1979 to 1989 and 1990 to 2000). The resistance level of all erythromycin-resistant C jejuni strains was low (MIC 8 to 16 mg/litre), while high-level (MIC ≥128 mg/litre) erythromycin-resistant strains were observed only in C coli. Low-level erythromycin-resistant strains might not be truly resistant, because the amount of carbon dioxide in the atmosphere increases the MICs of erythromycin (Rautelin and others 1991). Range of MIC (mg/litre) Profile by MQ-LiPA* Nalidixic acid Ofloxacin Erythromycin

Design of textile scaffolds for tissue engineering: the use of biodegradable yarns

The emergence of tissue engineering has led to the development of three‐dimensional cellular scaffolds that reconstruct the tissue structure. Research into the use of biodegradable materials in scaffolds has grown; the aim is that when tissue growth is complete, the scaffold degrades completely. This research aims to design novel scaffolds and investigates biodegradable polylactide (PLA) yarns; in particular, poly(l‐lactide) (PLLA) yarns extruded in‐house. To study degradation and determine the effect on the biodegradable yarns/textiles, they were immersed in phosphate buffer solution (PBS, pH=7.4) for various durations at 37°C. Mechanical properties were evaluated on tensile testing rigs and they were observed, before and after the immersion period. Cells were then cultured (37°C, 5 per cent carbon dioxide in air) on the textiles for 1 week. As expected, after immersion, the yarns exhibit a decrease in elongation and tenacity. Initial results indicate that the yarn properties influence cell attachment and spreading.

Prevalence of Bartonella species causing bacteraemia in domesticated and companion animals in the United Kingdom

Between October 1999 and February 2000, 691 blood samples examined routinely for either haematological or virological assessment were screened by culture for the presence of Bartonella species. They came from...

Turning off the heat: why America must double energy efficiency to save money and reduce global warming

Global warming, the result of increasing carbon dioxide emissions from energy producers and users, has become a danger to humans. It threatens radical climate changes, severe storms, and ecological havoc. Turning Off the Heat targets a main source of overuse of fossil fuels - the energy producers themselves who, through their government-approved monopolies have led to energy inefficiency and needless pollution. A leading authority with 20 years experience developing and operating of energy projects, Casten clearly explains that the US and other nations of the world can, and must, double the efficiency of electric utilities. This efficiency improvement will lead to a reduction of electric prices by 30 to 40 per cent and cut carbon dioxide emissions (a greenhouse gas) in half. Two-thirds of the fuel used to make US electricity is wasted, resulting in higher energy prices and excess pollution. If market forces are unleashed and monopolies ended, competition will save money and fuel, Casten says. This is an essential volume for policy-makers, legislators, leaders in industry, environmentalists, and concerned citizens.

Behaviour of pigs exposed to mixtures of gases and the time required to stun and kill them: welfare implications

Pigs were exposed individually to either 90 per cent argon in air (anoxia), a mixture of 30 per cent carbon dioxide and 60 per cent argon in air (hypercapnic anoxia)...

Occurrence and Origin of Water Well Methane Gas in Bangladesh

Abstract Gas occurrences in irrigation wells have been reported from most parts of the country, and in some parts of the southeast region, gas occurrences have become a limiting factor for groundwater development. Methane is the main component of water well gases and is readily identified by its ignition characteristics. It has been found that conditions required for gas formation, such as the amount of total organic carbon and organic matter, depth of burial, hydrothermal gradient and degree of compaction, are all favourable for the generation of biogenic gases in the deltaic regions of the Bengal Basin. Biogenic gas from water wells contains only methane as the hydrocarbon gas and along with more than one per cent (by volume) of carbon dioxide. On the other hand thermogenic gas from deep wells contains methane and other higher hydrocarbon gases along with less than one per cent of carbon dioxide. Areas marked by high groundwater salinity generates more methane than other parts of the country and this is suggestive of estuarine environment of deposition of the aquifer materials in those areas.

Comparison of media and conditions of incubation for the quantitative culture of Malassezia pachydermatis from canine skin

Fifty-five swab-wash specimens from dogs were cultured at 32°C on Sabouraud's dextrose agar either with or without 1 per cent Tween 80, Ushijima's medium A and modified Dixon's and Leeming's media. The counts of Malassezia pachydermatis were not significantly different after three or seven days of incubation. Colony counts on contact plates were significantly greater after incubation for seven days on Sabouraud's dextrose (P<0·001) and modified Dixon's agars (P<0·05) than after three days at 26°C, but not at 32°C. Counts on Sabouraud's or modified Dixon's agars after incubation at 32°C and 37°C were not significantly different. When compared with aerobic culture, an atmosphere containing 5 to 10 per cent carbon dioxide significantly (P<0·01) increased the frequency of isolation and colony counts on Sabouraud's dextrose agar but not on modified Dixon's agar.

The Vaginal Microbiota of Guinea Pigs

The vaginae of four guinea pigs were swabbed and samples cultured aerobically on horse blood agar, in 5 per cent carbon dioxide on MRS agar or anaerobically on anaerobic horse blood agar. Vaginal microbiota consisted almost exclusively of gram-positive bacteria including Corynebacterium, Streptococcus, Enterococcus, Staphylococcus and Lactobacillus species. Keywords: guinea pigs, vaginal microbiota, vaginal vaccines.

Welfare Implications of the Gas Stunning of Pigs 2. Stress of Induction of Anaesthesia

AbstractThe severity of respiratory distress occurring prior to loss of posture during exposure to: 20, 30, 40, 50, 60, 70, 80 or 90 per cent carbon dioxide in air; 2 or 5 per cent residual oxygen in argon; 30 per cent carbon dioxide in argon with either 2 or 5 per cent residual oxygen; or 40 per cent carbon dioxide in argon with either 2 or 5 per cent residual oxygen, was subjectively determined in pigs from their behaviour. The results indicated that exposure to 2 per cent oxygen in argon (anoxia) induced minimal respiratory distress, 30 per cent carbon dioxide in argon with 2 per cent residual oxygen induced a moderate distress and exposure to all the concentrations of carbon dioxide in air induced severe respiratory distress in the pigs. From the animal welfare point of view, using 2 per cent oxygen in argon (anoxia) appears to be the optimum choice for gas stunning pigs. Secondly, a mixture of 30 per cent carbon dioxide in argon with 2 per cent residual oxygen is preferred to 90 per cent carbon dioxide in air.

Successful 14-day preservation of rat skin using a two-layer cold-storage method

Skin-graft preservation for the purpose of delayed autografting to burn patients is a basic tool of plastic and burn surgery. This study was undertaken to evaluate the efficacy of the two-layer (physiological saline/perfluorochemical (PFC)) cold-storage method for skin preservation. In Wistar rats, a full-thickness skin graft, 3 cm in diameter, was harvested from the back, and separated from the dermis to obtain the epidermal sheet. This epidermal sheet was preserved at 4°C using physiological saline (group 1, n = 15), physiological saline bubbled with a 95 per cent oxygen, 5 per cent carbon dioxide mixture (group 2, n = 15) or a two-layer method with bubbling with 95 per cent oxygen and 5 per cent carbon dioxide mixture (group 3, n = 15). The epidermal skin sheets were then autotransplanted to the backs of the original donor rats 7, 10 and 14 days after the start of preservation. The success rate of the skin autotransplantation was determined by measuring the ratio of viable area to total graft area 7 days after grafting. In group 1, the success rates after 7, 10 and 14 days' perservation were 56.4, 47.4 and 0.09 per cent, respectively. In group 2, the corresponding success rates were 62.0, 48.4 and 0.8 per cent respectively, showing no improvement with oxygenated saline. In clear contrast, the success rates were significantly improved by the two-layer method, the values being 92.1, 87.9 and 77.6 per cent after 7, 10 and 14 days of perservation, respectively ( P < 0.01 vs. groups 1 and 2 for all preservation durations). Based on these results, we concluded that the two-layer method is useful for not only improving the quality of the skin graft but also extending the preservation time of the skin graft up to 14 days.

Welfare Implications of the Gas Stunning of Pigs 1. Determination of Aversion to the Initial Inhalation of Carbon Dioxide or Argon

AbstractThe aversive effects of 90 per cent argon in air, 30 per cent carbon dioxide in air or 90 per cent carbon dioxide in air were investigated in slaughter weight pigs. Aversion was assessed from their reluctance to enter the three gaseous atmospheres to obtain a reward (apples). The pigs did not show any aversion to the inhalation of 90 per cent argon in air. The majority of the pigs did not show aversion to the presence of 30 per cent carbon dioxide in air. By contrast, the inhalation of 90 per cent carbon dioxide was aversive to the majority of the pigs. Fasting them for up to 24h prior to testing did not overcome the pigs ‘ reluctance to enter an atmosphere containing 90 per cent carbon dioxide.

Euthanasia of day-old chicks with carbon dioxide and argon.

The efficacy for the euthanasia of day-old chicks of mixtures of carbon dioxide and air, or carbon dioxide and argon containing 1, 2 or 5 per cent residual oxygen, or argon containing 1 or 2 per cent residual oxygen was tested in three experiments. The time to the onset of unconsciousness of individual chicks, determined from the time to loss of posture, was similar during their exposure to 2 per cent oxygen in argon, 20, 30 or 40 per cent carbon dioxide in argon with 2 per cent residual oxygen, or 90 per cent carbon dioxide in air. The exposure of chicks in batches of 20 to a mixture of 20, 30 or 40 per cent carbon dioxide in argon resulted in the death of all the chicks within two minutes. However, a residual oxygen level of 5 per cent in these mixtures resulted in the survival of some chicks for longer than two minutes. With argon alone the level of residual oxygen was critical; less than 2 per cent was essential to achieve 100 per cent mortality within three minutes, and a rise from 2 to about 3 per cent resulted in up to 20 per cent of the chicks surviving for seven minutes.

Effect of the method of stunning and the interval between stunning and neck cutting on blood loss in turkeys

Turkey hens were stunned by inducing anoxia with either argon (with approximately 2 per cent residual oxygen) or 30 per cent carbon dioxide in argon with 2 per cent residual oxygen, and the carcases were bled either immediately or five or 10 minutes after they had been stunned. A control group of turkeys was stunned electrically (250 mA for about four seconds) and had their necks cut immediately after stunning. The amount of blood lost was measured and expressed as a percentage of liveweight. The results showed that the necks of gas-stunned turkeys can be cut up to 10 minutes after they have been stunned without reducing the total blood loss significantly.

An evaluation of humane gas stunning methods for turkeys

Spontaneous electroencephalograms (EEG) and somatosensory evoked potentials (SEPS) were recorded in turkeys while they were kept in an atmosphere of either 49 or 86 per cent carbon dioxide in air. The time to the loss of SEPS was not related to the concentration of carbon dioxide, but the time to the onset of an isoelectric EEG was shorter at the higher concentration of carbon dioxide. In comparison with other gas stunning methods it was considered that stunning with these high concentrations of carbon dioxide would not have any welfare advantages over stunning in argon with 2 per cent residual oxygen or in a mixture of 30 per cent carbon dioxide and 60 per cent argon in air.

An investigation into the batch killing of turkeys in their transport containers using mixtures of gases

This study was carried out under commercial conditions to investigate the feasibility of killing turkeys while they were still in their transport containers, with a mixture of gases, and to compare the effects of this method and electrical stunning on the prevalence of carcase downgrading conditions and haemorrhages in the breast muscles. The results showed that turkeys could be readily killed while still in their transport containers by using either anoxia induced with 90 per cent argon in air or hypercapnic anoxia induced with a mixture of 30 per cent carbon dioxide and 60 per cent argon in air, and that the prevalence of carcase-downgrading conditions and haemorrhages in the breast muscles was lower after killing the turkeys with the gases.

Time to loss of somatosensory evoked potentials and onset of changes in the spontaneous electroencephalogram of turkeys during gas stunning

The times to the loss of somatosensory evoked potentials (SEPs) and the onset of suppressed and isoelectric electroencephalogram (EEG) were investigated in turkeys as they were stunned with gas mixtures consisting of one of three mixtures: (A) 30 per cent carbon dioxide and 60 per cent argon in air (2 per cent residual oxygen and 8 per cent residual nitrogen); (B) 90 per cent argon in air (2 per cent residual oxygen and 8 per cent residual nitrogen); (C) 65 per cent carbon dioxide in air (7 per cent residual oxygen and 28 per cent residual nitrogen). The time to the loss of SEPs, EEG suppression and the onset of an isoelectric EEG, respectively, were 22, 16 and 35 seconds in mixture A, 44, 41 and 101 seconds in mixture B, and 15, 15 and 67 seconds in mixture C. Stunning turkeys with mixture A or B would be suitable under commercial conditions. Mixture C, containing 65 per cent carbon dioxide in air, is considered on humanitarian grounds to be unacceptable for stunning turkeys owing to the pungency of the carbon dioxide at this concentration.

Changes in the spontaneous and evoked electrical activity in the brain of hens during stunning with 30 per cent carbon dioxide in argon with 5 per cent residual oxygen

Changes in the somatosensory evoked potentials ( SEPS) and spontaneous electroencephalogram ( EEG) in hens were investigated during stunning with a mixture of 30 per cent carbon dioxide in argon with 5 per cent residual oxygen. The results showed that the SEPS were lost on average in 17 seconds (maximum 28 seconds), which is similar to the 19 seconds (maximum 32 seconds) reported while stunning hens with a mixture of 30 per cent carbon dioxide in argon with 2 per cent residual oxygen. The spontaneous EEG showed suppression and a quiescent phase at 14 and 58 seconds, respectively. It is concluded that a mixture of 30 per cent carbon dioxide in argon with 2 per cent residual oxygen would be ideally suited for batch stunning chickens and any inadvertent increase in the residual oxygen level up to 5 per cent in the stunning atmosphere would not lead to inadequate stunning or recovery of consciousness before neck cutting.