Ammonia and carbon dioxide concentrations in disposable and reusable static mouse cages

To identify the most practical and representative sampling locations for air quality and environmental variables inside intensive piggery buildings, the variation in the spatial, diurnal and seasonal concentration of major airborne pollutants, and related environmental parameters, were analysed over a 2.5-day period at several locations within different piggery buildings. Major airborne pollutants including, ammonia, carbon dioxide, and airborne particles were monitored along with environmental parameters of airspeed, temperature and humidity. To determine the air quality within each building, cyclone attachments were installed to measure particles of less than 5 mm along with a seven hole sampler attachment to measure inhalable airborne particles. An Osiris optical particle counter also monitored the concentrations of airborne particles. Ammonia and carbon dioxide were monitored using a multi-gas monitoring machine and airspeed was measured using a hot-wired anemometer. Interesting patterns in the concentration of carbon dioxide, dust and ammonia were observed over time and space. Carbon dioxide, airspeed and dust concentration demonstrated an obvious circadian pattern. The difference in the concentrations of ammonia and carbon dioxide was not statistically significant at alternative sampling locations inside each building. However, the gravimetric measurements indicated that the concentrations of inhalable particles were not uniform throughout the buildings and proved to be higher above the walkways. Ammonia and respirable particle concentrations were significantly higher in summer when compared to winter conditions. These results combined, identified the most appropriate sampling times and sampling places for reliable evaluation of air quality in intensive livestock buildings.

SUMMARY The housing system plays a critical role in welfare of laying hens, and various systems have been implemented throughout the world. Benefits vary for different housing schemes. Important considerations for welfare also include environmental conditions (air quality), but these parameters are not well documented for different laying hen housing systems. Regarding the consequences of poor air quality, it includes diminished production performance and impaired bird health. Therefore, the objective of this research was to assess the air quality in three housing system types for laying hens. One farm from each type (conventional cages, furnished cages and alternative system) was selected, based on farm access and availability. The evaluated environmental variables included: ammonia concentration, carbon dioxide concentration, air temperature, relative humidity, air flow velocity, bacteria and fungi. All parameters were determined using hygiene specific methods, in three different points, in three consecutive days in the summer. The temperature was adequate in all the hen houses, while the relative humidity was below the hygienic norms in the system with furnished cages. The air currents’ velocity was lower than is recommended by welfare standards, in all the assessed farms. The concentration of carbon dioxide was below the threshold limit in all three housing types, higher values being recorded in the alternative system (900 ppm). The ammonia concentration varied (5-25 ppm), being significantly (p<0.05) higher in the alternative system comparing with the conventional and furnished cage housing. The numbers of bacteria (4.49 x 10 6 CFU/m 3 ) and fungi (1.49 x 10 5 CFU/m 3 ) were significantly (p<0.05) higher in the alternative system, comparing with the other two systems. Significant differences (p<0.05) were also found between the conventional cages and the furnished ones for the total number of mesophilic bacteria (5.07 x 10 5 CFU/m 3 and 8.47 x 10 4 CFU/m 3 , respectively). The obtained values are conformable with the results of other studies (Matkovic et al., 2007; Nimmermark et al., 2009). The air quality problems are more frequently encountered in the systems where the birds are kept on the floors than in cage systems, especially in those hen houses where the ventilation rates are low, but these can also be significant in cage housing due to the hens’ manure. The results of the study indicate better air quality in the system with furnished cages comparing with the other two housing systems.

Study DesignA single surgeon, retrospective case series.PurposeThis study aimed to compare the radiological outcomes after using expandable versus static cages in oblique lumbar interbody fusion (OLIF).Overview of LiteratureOLIF enables access to the spine while avoiding the anterior vessels and psoas muscles via a retroperitoneal corridor. Static cages have been used in this approach; however, they present with limitations, including repeated trialing, resulting in endplate violation and implant subsidence.MethodsPatients who underwent OLIF (n=86) were divided into expandable (n=39) and static cage (n=47) groups. Radiographic data were then analyzed preoperatively and postoperatively, including immediate, 3 months, and the most recent follow-up.ResultsCage type predicted the incidence of subsidence, with expandable cages associated with 4.00 and 2.43 fewer instances of subsidence compared with static cages at the postoperative and most recent time points (p<0.05). Cage type was a significant predictor of the change in height in both the posterior disk and foraminal height (FH) models. Expandable cages were associated with improved posterior disk height (DH) expansion at all three time points (1.24 mm, 0.88 mm, and 1.85 mm, respectively; p<0.01), and with larger FH increases at the 3 months postoperatively and most recent follow-up (1.12 mm, 0.40 mm, and 1.28 mm, respectively; p=0.096, 0.016, and 0.030). The expandable cage type was associated with improvement (3.46°, 3.12°, and 3.36°; p<0.01, 0.05, and 0.08, respectively) at the postoperative and 3-month time points when predicting the change in segmental lordosis. No statistically significant differences were found between the groups in disk angle and lumbar lordosis measurements or baseline demographics.ConclusionsThe results of this study indicate that both static and expandable cages result in radiographic improvement in posterior DH, segmental lordosis, and FH when used in OLIF. Expandable cages may demonstrate certain advantages over static cages due to lower implant subsidence instances and the greater posterior disk and FH expansion, thereby providing preliminary evidence to support the superiority of expandable cages in OLIF procedures.

Abstract. Roofed beef cattle finishing facilities with under-floor deep pit manure storage are increasing in number, despite limited data on the gas production and concentration conditions for this style of housing and manure management. This paper presents ammonia (NH3) and carbon dioxide (CO2) concentration distributions for three finishing beef cattle barns (Barns F, H and R) with under-floor deep pit manure storage, for summer, fall and spring weather conditions in Midwest US. The three barns were variable in size and layout, roof style, stocking density and management practices. On each of the three sampling days per barn, three sets of air samples were collected in Tedlar bags to represent the concentrations above the manure surface, at floor level, at nose level, and in the north and south wall openings for four pens. The effect of pen, sampling location, season and interactions were analyzed for each individual site. Location and season were significant factors affecting ammonia and carbon dioxide concentration measurements for Barn R, but there was a significant interaction of these factors for Barn F and H NH3 and CO2 concentrations. There was a larger variation in the gas concentrations over the manure surface by season than for gas measurements elsewhere in the barn, and this is attributed to temperature and manure characteristic changes between seasons. The ammonia concentration over the manure surface ranged from 14 to 61 ppm for Barn F over the three seasons, and 1 to 9 ppm for Barns H and R. However, at nose and floor level, average ammonia concentration levels were less than 9 ppm for all three barns and seasons. There was also a significant interaction of pen and season for NH3 at Barn H. This may relate to pen position over the two manure storage pits. The interaction of pen and season for CO2 concentrations was significant for Barns F and R. This difference may be related to differences in manure characteristics, but also stocking density. This information demonstrates the variability between production-scale barns, and informs the design of future concentration and emission modeling efforts.

The Development of Robust Methods for Measuring Concentrations and Emission Rates of Gaseous and Particulate Air Pollutants in Livestock Buildings

INTRODUCTION: It has been shown that expandable cages for transforaminal lumbar interbody fusion (TLIF) are associated with increased rates of subsidence. However, as lateral lumbar interbody fusion (LLIF) cages offer substantially larger footprints, this may offset the risks. METHODS: A retrospective review was performed of a consecutive adult patients undergoing LLIF with either static or expandable cages from 2013-2021. Demographics and surgical details were collected. Posterior disc height (PDH), subsidence, and fusions status were compared between patients with static and expandable cages. Follow-up were reported at minimum 6-months and 1-year. RESULTS: A total of 120 patients had 173 cages implanted: 96 patients with 143 static cages vs. 24 patients with 30 expandable cages. Mean age was 63.4 and 62.4% were male. There were no significant differences in age, gender, BMI, smoking, or osteoporosis. Overall, PDH was significantly increased following LLIF (4.1 v 7.4 mm, p &lt; 0.001). Static and expandable cage types had similar magnitude (3.7 v 3.3 mm, p = 0.311) and percentage (89.0% v 121.5%, p = 0.127) change in PDH, respectively. Overall incidence of cage subsidence at 6-months and 1-year was 6.9% and 10.4% respectively. There was no significant difference in subsidence rates between cage types at 6 months (7.0% v 6.7%, p = 0.949) and 1-year (11.2 v 6.7%, p = 0.461). Radiographic evidence of fusion was present in 92.7% of cases at 1-year, and both cage types achieved similar fusion rates as well (92.2% v 95.6%, p = 0.555). CONCLUSIONS: LLIF static and expandable cages offer similar PDH restoration depending on surgical goals. Expandable cages seem to be less prone to subsidence than smaller TLIF cage counterparts and offer similar fusion rates to static cages. Larger cohort studies are warranted to further validate these findings which are ongoing.

Potential advantages of using expandable versus static cages during transforaminal lumbar interbody fusion (TLIF) are not fully established. The authors aimed to compare the long-term radiographic outcomes of expandable versus static TLIF cages. A retrospective review of 1- and 2-level TLIFs over a 10-year period with expandable and static cages was performed at the University of California, San Francisco. Patients with posterior column osteotomy (PCO) were subdivided. Fusion assessment, cage subsidence, anterior and posterior disc height, foraminal dimensions, pelvic incidence (PI), segmental lordosis (SL), lumbar lordosis (LL), pelvic incidence-lumbar lordosis mismatch (PI-LL), pelvic tilt (PT), sacral slope (SS), and sagittal vertical axis (SVA) were assessed. A consecutive series of 178 patients (with a total of 210 levels) who underwent TLIF using either static (148 levels) or expandable cages (62 levels) was reviewed. The mean patient age was 60.3 ± 11.5 years and 62.8 ± 14.1 years for the static and expandable cage groups, respectively. The mean follow-up was 42.9 ± 29.4 months for the static cage group and 27.6 ± 14.1 months for the expandable cage group. Within the 1-level TLIF group, the SL and PI-LL improved with statistical significance regardless of whether PCO was performed; however, the static group with PCOs also had statistically significant improvement in LL and SVA. The expandable cage with PCO subgroup had significant improvement in SL only. All of the foraminal parameters improved with statistical significance, regardless of the type of cages used; however, the expandable cage group had greater improvement in disc height restoration. The incidence of cage subsidence was higher in the expandable group (19.7% vs 5.4%, p = 0.0017). Within the expandable group, the unilateral facetectomy-only subgroup had a 5.6 times higher subsidence rate than the PCO subgroup (26.8% vs 4.8%, p = 0.04). Four expandable cages collapsed over time. Expandable TLIF cages may initially restore disc height better than static cages, but they also have higher rates of subsidence. Unilateral facetectomy alone may result in more subsidence with expandable cages than using bilateral PCO, potentially because of insufficient facet release. Although expandable cages may have more power to induce lordosis and restore disc height than static cages, subsidence and endplate violation may negate any significant gains compared to static cages.

The effect of ventilation on concentrations of ammonia in typical Finnish cowhouses was investigated. Temperature, relative humidity, and concentration of carbon dioxide also were measured. The measurements were made in autumn and winter at six farms, each with a cowhouse accommodating approximately 20 milk cows. A tracer-gas technique and multipoint equipment measured ventilation. Samples for airborne ammonia were collected in impinger flasks and analyzed by a gas-specific electrode. Ammonia was also measured at the same sites by diffusion tubes. The mean rate of ventilation varied from 2.2 to 6.5 room changes per hour and the mean concentration of ammonia from 4.2 to 15.4 ppm. The correlation between ventilation rates and concentrations of ammonia was poor, indicating that ammonia concentrations are also affected by other factors. In all except one cowhouse the ventilation rates were within established limits. The lowest concentrations of airborne ammonia were found in cowhouses equipped with a low exhaust system of ventilation through manure channels. To reduce air impurities and relative humidity, it is recommended that ventilation rates be increased. Litter should also be used to reduce levels of ammonia. To avoid temperatures below the recommended level and to prevent high air velocities, it was found that supply air should be warmed in winter. The diffusion tubes used for ammonia were found to be reliable and sensitive enough for field purposes and are the most suitable for evaluating farmers' exposure to airborne ammonia.

Characteristics of the large-scale circulation during episodes with high and low concentrations of carbon dioxide and air pollutants at an arctic monitoring site in winter

Sagittal alignment is an important consideration in spine surgery. The literature is conflicted regarding the effect of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) on sagittal parameters and the role of expandable cage technology. To compare lordosis generated by static and expandable cages and to determine what factors affect postoperative sagittal parameters. Preoperative regional lordosis (RL), segmental lordosis (SL), and posterior disc height (PDH) were compared to postoperative values in single-level MI-TLIF performed using expandable or static cages. Patients were stratified based on preoperative SL: low lordosis (<15 degrees), moderate lordosis (15-25 degrees), and high lordosis (>25 degrees). Regression analyses were conducted to determine factors associated with postoperative SL and PDH. Of the 171 patients included, 111 were in the static and 60 in the expandable cohorts. Patients with low preoperative lordosis experienced an increase in SL and maintained RL regardless of cage type. Those with moderate to high preoperative lordosis experienced a decrease in SL and RL with the static cage, but maintained SL and RL with the expandable cage. Although both cohorts showed an increase in PDH, the increase in the expandable cohort was greater. Preoperative SL was predictive of postoperative SL; preoperative SL, preoperative PDH, and cage type were predictive of postoperative PDH. Expandable cages showed favorable results in restoring disc height and maintaining lordosis in the immediate postoperative period. Preoperative SL was the most significant predictor of postoperative SL. Thus, preoperative radiographic parameters and goals of surgery should be important considerations in surgical planning.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

The aim of the research presented here was to model the effects of important housing andmanagement factors on the concentrations of ammonia and carbon dioxide in order to predict andcontrol the internal concentrations and emissions of these gases from piggery buildings. Theproject aim was achieved by conducting a comprehensive survey (160 piggery buildings in foursstates of Australia between autumn 1997 and autumn 1999) and measuring the concentrations ofthese gases in the study buildings. Ammonia and carbon dioxide concentrations were measuredcontinuously over 60 hours at each monitoring occasions using a multi-gas monitoring machine(MGM). Engineering and management characteristics of the piggery buildings were recorded atthe time of sampling and used in the subsequent multivariate analysis. The mean ammonia andcarbon dioxide concentrations measured in the piggery buildings were 3.7 ppm and 858 ppm,respectively. A general linear model (GLM PROC) statistical procedure was used to model theeffects of housing and management factors on the concentrations of ammonia and carbondioxide. According to the model developed, ammonia concentrations were primarily affected bythe level of pen hygiene, shed size, pig flow management and seasons. Carbon dioxideconcentrations were affected by the classification of the buildings, seasons, ventilation control ofthe wall and ridge vent openings, ceiling height of the buildings, size of the wall openings andheight of the ridge vent opening. The results highlighted potential strategies to be used to reducethe negative effects of poor air quality on pig production, environment, health and welfare andthe working environment of piggery staff.

In livestock production, the air quality inside the buildings is known to have an impact on health and life quality of workers as well as on the animal performance. Milk-fed calf producers are concerned about this, especially during the winter period when the ventilation is reduced. This study was carried out to evaluate the air quality inside milk-fed calf buildings during three periods (winter, spring and summer) to quantify the risk for workers related to air quality. Three farms having different ventilation systems typically found in Quebec (pre-heated hallways, lateral air inlets and chimney fans) were studied. Data measurements included ammonia (NH3), hydrogen sulphide (H2S), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) concentrations, as well as the ambient conditions like temperature, relative humidity and atmospheric pressure. Gas samples were drawn from inside the building to a mobile instrumentation trailer via Teflon tubing. Sample were analysed using a flame ionisation detector (NH3), an electrochemical H2S sensor and a gas chromatograph (CH4, N2O and CO2). Flow rates from the ventilation system were also measured in order to calculate gas emissions. Results show that there is no important problem of air quality inside milk-fed calf building. The average indoor temperature was properly controlled while the relative humidity was higher than recommendations. The ammoniac was the only gas reaching a concentration close to the maximum time-weighted average recommended for human health. A better control of the minimum ventilation rate should rectify both the relative humidity level and the ammonia concentrations.

The influences of temperature, relative humidity (RH) and carbon dioxide (CO2) concentration on concrete carbonation in a simulated environment were investigated. The carbonation depth, compressive strength and surface strain of concrete under different simulated environments were tested. The results showed that the effects of temperature, RH and carbon dioxide concentration on carbonation depth and compressive strength were significant. There was a linear relation between temperature and carbonation depth as well as compressive strength of concrete. A power function existed between carbon dioxide concentration and carbonation depth, and there was an exponential function between carbon dioxide concentration and compressive strength. The carbonation of concrete was more significant when the RH was within the range 60­–80%. Significant differences of phase composition and hydration products were observed before and after the carbonation, mainly manifested as attenuation and disappearance of diffraction peaks of hydration products.

Diffusivity is a strong function of concentration and an important transport property. Diffusion of multiple species is far more frequent than the diffusion of one species. However, there are limited experimental data available on multi-component diffusivity. The objective of this study is to develop an optimal control framework to determine multi-component concentration-dependent diffusivities of two gases in a non-volatile phase such as polymer. In Part 1 of this study, we derived a detailed mass-transfer model of the experimental diffusion process for the non-volatile phase to provide the temporal masses of gases in the polymer. The determination of diffusivities is an inverse problem involving principles of optimal control. Necessary conditions are determined to solve this problem. In Part 2 of this study, we utilized the results of Part 1 to determine the concentration-dependent, multi-component diffusivities of nitrogen and carbon dioxide in polystyrene. To that end, solubility and diffusion experiments are conducted to obtain necessary data. In the ternary system of nitrogen (1), carbon dioxide (2), and polystyrene (3), the diffusivities and D11, D12, D21, and D22 versus the gas mass fractions are two-dimensional surfaces. The diffusivity of carbon dioxide was found to be greater than that of nitrogen. The value of the main diffusion coefficient D11 was found to increase as the concentration of carbon dioxide increased. The highest value of D11 obtained was 2.2 X 10^-8m^2s^-1 for nitrogen mass fraction of 3.14 X10^-4 and for a carbon dioxide mass fraction of 5.67 X 10^-4 . The cross-diffusion coefficient increased as the concentrations of nitrogen and carbon dioxide increased. The diffusivity reached its maximum value when the concentrations of nitrogen and carbon dioxide were at their maximum values. The diffusivity was of the order of 10^-9m^2s^-1. The diffusivity of the cross-diffusion coefficient D21 was found to be increased for the mass The diffusivity of the cross-diffusion coefficient was found to be increased for the mass fractions of carbon dioxide ranging from 0 to 1.70 X 10^-3 . The diffusivity was found to be of the order of . The diffusion coefficient, D22, was found to increase with the concentrations of nitrogen and carbon dioxide, D22 remained high with low concentrations of carbon dioxide. The diffusivity was found to be of the order of 10^-7m^2s^-1