957 resultados para TGM concentration in air


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Single phase (Zn,Fe)(1-x) O zincite solid solution samples have been prepared by high temperature equilibration in air and in reducing atmospheres, followed by quenching to room temperature. The Fe2+/Fe3+ concentrations in the samples have been determined using wet chemical and XPS techniques. Iron is found to be present in zincite predominantly in the form of Fe3+ ions. The transition from an equiaxed grain morphology to plate-like zincite crystals is shown to be associated with increasing Fe3+ concentration, increasing elongation in < 001 > of the hexagonal crystals and increasing anisotropic strain along the c-axis. The plate-like crystals are shown to contain planar defects and zincite polytypes at high iron concentrations.

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A specially-designed vertical wind tunnel was used to freely suspend individual liquid drops of 5 mm initial diameter to investigate drop dynamics, terminal velocity and heat and mass transfer rates. Droplets of distilled, de-ionised water, n-propanol, iso-butanol, monoethanolamine and heptane were studied over a temperature range of 50oC to 82oC. The effects of substances that may provide drop surface rigidity (e.g. surface active agents, binders and polymers) on mass transfer rates were investigated by doping distilled de-ionised water drops with sodium di-octyl sulfo-succinate surfactant. Mass transfer rates decreased with reduced drop oscillation as a result of surfactant addition, confirming the importance of droplet surface instability. Rigid naphthalene spheres and drops which formed a skin were also studied; the results confirmed the reduced transfer rates in the absence of drop fluidity. Following consideration of fundamental drop dynamics in air and experimental results from this study, a novel dimensionless group, the Oteng-Attakora, (OT), number was included in the mass transfer equation to account for droplet surface behaviour and for prediction of heat and mass transfer rates from single drops which exhibit surface instability at Re>=500. The OT number and the modified mass transfer equation are respectively: OT=(ava2/d).de1.5(d/) Sh = 2 + 0.02OT0.15Re0.88Sc0.33 Under all conditions drop terminal velocity increased linearly with the square root of drop diameter and the drag coefficient was 1. The data were correlated with a modified equation by Finlay as follows: CD=0.237.((Re/P0.13)1.55(1/We.P0.13) The relevance of the new model to practical evaporative spray processes is discussed.

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The 9/11 Act mandates the inspection of 100% of cargo shipments entering the U.S. by 2012 and 100% inspection of air cargo by March 2010. So far, only 5% of inbound shipping containers are inspected thoroughly while air cargo inspections have fared better at 50%. Government officials have admitted that these milestones cannot be met since the appropriate technology does not exist. This research presents a novel planar solid phase microextraction (PSPME) device with enhanced surface area and capacity for collection of the volatile chemical signatures in air that are emitted from illicit compounds for direct introduction into ion mobility spectrometers (IMS) for detection. These IMS detectors are widely used to detect particles of illicit substances and do not have to be adapted specifically to this technology. For static extractions, PDMS and sol-gel PDMS PSPME devices provide significant increases in sensitivity over conventional fiber SPME. Results show a 50–400 times increase in mass detected of piperonal and a 2–4 times increase for TNT. In a blind study of 6 cases suspected to contain varying amounts of MDMA, PSPME-IMS correctly detected 5 positive cases with no false positives or negatives. One of these cases had minimal amounts of MDMA resulting in a false negative response for fiber SPME-IMS. A La (dihed) phase chemistry has shown an increase in the extraction efficiency of TNT and 2,4-DNT and enhanced retention over time. An alternative PSPME device was also developed for the rapid (seconds) dynamic sampling and preconcentration of large volumes of air for direct thermal desorption into an IMS. This device affords high extraction efficiencies due to strong retention properties under ambient conditions resulting in ppt detection limits when 3.5 L of air are sampled over the course of 10 seconds. Dynamic PSPME was used to sample the headspace over the following: MDMA tablets (12–40 ng detected of piperonal), high explosives (Pentolite) (0.6 ng detected of TNT), and several smokeless powders (26–35 ng of 2,4-DNT and 11–74 ng DPA detected). PSPME-IMS technology is flexible to end-user needs, is low-cost, rapid, sensitive, easy to use, easy to implement, and effective. ^

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Camu-camu (Myrciaria dubia H.B.K. (McVaugh)) is a native Amazon fruit, recognized worldwide as one of the main natural sources of ascorbic acid. Due to its great acidity, this fruit is generally consumed after processing into juice or as ingredient in food preparations. As a co-product of the camu-camu processing, a significant amount of agroindustrial residue is generated. Despite the studies showing the bioactive value and biological potential of the fruit, few studies have approached the possible processing techniques, transformation and preservation of camu-camu fruits and its agroindustrial pomace. Therefore, the present work has the objective of evaluating two different drying processes applied to camu-camu pomace (peel and seeds with residual pulp), freeze drying and hot air drying, in order to obtain a functional fruit product. This thesis was divided into three stages: the first one shows the studies related to the freeze drying and hot air drying, where we demonstrated the impact of the selected drying techniques on the bioactive components of camu-camu, taking the fresh pomace as the control group. Among the investigated conditions, the groups obtained at 50ºC and 4 m/s (SC50) and 80ºC and 6 m/s (SC80) were selected as for further studies, based on their ascorbic acid final content and Folin-Ciocalteau reducing capacity. In addition to SC50 and SC80, the fresh pomace (RF) and freeze dried (RL) samples were also evaluated in these further stages of the research. Overall, the results show higher bioactive concentration in the RF samples, followed by RL, SC50 and SC80. On the second step of the research, the antioxidant, antimicrobial and antienzymatic activities were evaluated and the same tendency was observed. It was also reported, for the first time in the literature, the presence of syringic acid in dried camu-camu pomace. In the third and final stage of the research, it was investigated the effect of dried camu-camu on aging and neuroprotective disorders, using the in vivo model C.elegans. It was observed that camu-camu extracts were able to modulate important signaling genes relevant to thermal and oxidative stresses (p < 0.05). The polar acid, polar basic and polar neutral fractions obtained from the low molecular extracts of SC50 were able to extend the lifespan of wild type N2 C. elegans in 20% and 13% (p < 0.001). Results also showed that the paralysis induced by the β1-42 amyloid was significantly (p < 0.0001) retarded in CL4176 worms. Similarly, the camu-camu extracts attenuated the dopaminergic induction associated to Parkinson’s disease. Finally, a global analysis of the data presented here reveal that the camu-camu pomace, a co-product obtained from the industrial processing of a native Brazilian fruit, is a relevant natural source of health relevant compounds. This thesis, shows for the first time, the multifunctionality of camu-camu pomace, a natural resource still underexploited for scientific, commercial and technological purposes.

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We analyzed projections of current and future ambient temperatures along the eastern United States in relationship to the thermal tolerance of harbor seals in air. Using the earth systems model (HadGEM2-ES) and representative concentration pathways (RCPs) 4.5 and 8.5, which are indicative of two different atmospheric CO2 concentrations, we were able to examine possible shifts in distribution based on three metrics: current preferences, the thermal limit of juveniles, and the thermal limits of adults. Our analysis focused on average ambient temperatures because harbor seals are least effective at regulating their body temperature in air, making them most susceptible to rising air temperatures in the coming years. Our study focused on the months of May, June, and August from 2041-2060 (2050) and 2061-2080 (2070) as these are the historic months in which harbor seals are known to annually come ashore to pup, breed, and molt. May, June, and August are also some of the warmest months of the year. We found that breeding colonies along the eastern United States will be limited by the thermal tolerance of juvenile harbor seals in air, while their foraging range will extend as far south as the thermal tolerance of adult harbor seals in air. Our analysis revealed that in 2070, harbor seal pups should be absent from the United States coastline nearing the end of the summer due to exceptionally high air temperatures.

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We carried out short term pCO2/pH perturbation experiments in the coastal waters of the South China Sea to evaluate the combined effects of seawater acidification (low pH/high pCO2) and solar UV radiation (UVR, 280-400 nm) on photosynthetic carbon fixation of phytoplankton assemblages. Under photosynthetically active radiation (PAR) alone treatments, reduced pCO2 (190 ppmv) with increased pH resulted in a significant decrease in the photosynthetic carbon fixation rate (about 23%), while enriched pCO2 (700 ppmv) with lowered pH had no significant effect on the photosynthetic performance compared to the ambient level. The apparent photosynthetic efficiency decreased under the reduced pCO2 level, probably due to C-limitation as well as energy being diverged for up-regulation of carbon concentrating mechanisms (CCMs). In the presence of UVR, both UV-A and UV-B caused photosynthetic inhibition, though UV-A appeared to enhance the photosynthetic efficiency under lower PAR levels. UV-B caused less inhibition of photosynthesis under the reduced pCO2 level, probably because of its contribution to the inorganic carbon (Ci)-acquisition processes. Under the seawater acidification conditions (enriched pCO2), both UV-A and UV-B reduced the photosynthetic carbon fixation to higher extents compared to the ambient pCO2 conditions. We conclude that solar UV and seawater acidification could synergistically inhibit photosynthesis.

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[EN]Rn has been detected in 28 groundwater samples from the northeast of Gran Canaria (Canary Islands, Spain) utilizing a closed loop system consisting of an AlphaGUARD monitor that measures radon activity concentration in the air by means of an ionization chamber, and an AquaKIT set that transfers dissolved radon in the water samples to the air within the circuit. Radon concentration in the water samples studied varies between 0.3 and 76.9 Bq/L. Spanish radiological protection regulations limit the concentration of 222Rn for drinking water to 100 Bq/L, therefore the values obtained for all the analyzed samples are below this threshold. The hydrogeological study reveals a significant correspondence between the radon activity concentration and the material characteristics of the aquifer.

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Botrytis cinerea (Grey mould) is a necrotrophic fungus infecting over 230 plant species worldwide. It can cause major pre- and post-harvest diseases of many agronomic and horticultural crops. Botrytis cinerea causes annual economic losses of 10–100 billion US dollars worldwide and instability in the food supply (Jin and Wu, 2015). Grey mould losses, either at the farm gate or later in the food chain, could be reduced with improved knowledge of inoculum availability during production. In this paper, we report on the ability to monitor Botrytis spore concentration in glasshouse tomato production ahead of symptom development on plants. Using a light weight and portable air sampler (microtitre immunospore trap) it was possible to quantify inoculum availability within hours. Also, this study investigated the spatial aspect of the pathogen with an increase of B. cinerea concentration in bio-aerosols collected in the lower part of the glasshouse (0.5 m) and adjacent to the trained stems of the tomato plants. No obvious relationship was observed between B. cinerea concentration and the internal glasshouse environmental parameters of temperature and relative humidity. However the occurrence of higher outside wind speeds did increase the prevalence of B. cinerea conidia in the cropping environment of a vented glasshouse. Knowledge of inoculum availability at time periods when the environmental risk of pathogen infection is high should improve the targeted use and effectiveness of control inputs.

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Background: Very few studies regarding fungal and particulate matter (PM) exposure in feed industry have been reported, although such contaminants are likely to be a significant contributing factor to several symptoms reported among workers. The purpose of this study has been to characterize fungal and dust exposure in one Portuguese feed industry. Material and Methods: Air and surface samples were collected and subject to further macro- and microscopic observations. In addition we collected other air samples in order to perform real-time quantitative polymerase chain reaction (PCR) amplification of genes from Aspergillus fumigatus and Aspergillus flavus complexes as well as Stachybotrys chartarum. Additionally, two exposure metrics were considered – particle mass concentration (PMC), measured in 5 different sizes (PM0.5, PM1, PM2.5, PM5, PM10), and particle number concentration (PNC) based on results given in 6 different sizes in terms of diameter (0.3 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm and 10 μm). Results: Species from the Aspergillus fumigatus complex were the most abundant in air (46.6%) and in surfaces, Penicillium genus was the most frequently found (32%). The only DNA was detected from A. fumigatus complex. The most prevalent in dust samples were smaller particles which may reach deep into the respiratory system and trigger not only local effects but also the systemic ones. Conclusions: Future research work must be developed aiming at assessing the real health effects of these co-exposures.

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Metabolism in an environment containing of 21% oxygen has a high risk of oxidative damage due to the formation of reactive oxygen species. Therefore, plants have evolved an antioxidant system consisting of metabolites and enzymes that either directly scavenge ROS or recycle the antioxidant metabolites. Ozone is a temporally dynamic molecule that is both naturally occurring as well as an environmental pollutant that is predicted to increase in concentration in the future as anthropogenic precursor emissions rise. It has been hypothesized that any elevation in ozone concentration will cause increased oxidative stress in plants and therefore enhanced subsequent antioxidant metabolism, but evidence for this response is variable. Along with increasing atmospheric ozone concentrations, atmospheric carbon dioxide concentration is also rising and is predicted to continue rising in the future. The effect of elevated carbon dioxide concentrations on antioxidant metabolism varies among different studies in the literature. Therefore, the question of how antioxidant metabolism will be affected in the most realistic future atmosphere, with increased carbon dioxide concentration and increased ozone concentration, has yet to be answered, and is the subject of my thesis research. First, in order to capture as much of the variability in the antioxidant system as possible, I developed a suite of high-throughput quantitative assays for a variety of antioxidant metabolites and enzymes. I optimized these assays for Glycine max (soybean), one of the most important food crops in the world. These assays provide accurate, rapid and high-throughput measures of both the general and specific antioxidant action of plant tissue extracts. Second, I investigated how growth at either elevated carbon dioxide concentration or chronic elevated ozone concentration altered antioxidant metabolism, and the ability of soybean to respond to an acute oxidative stress in a controlled environment study. I found that growth at chronic elevated ozone concentration increased the antioxidant capacity of leaves, but was unchanged or only slightly increased following an acute oxidative stress, suggesting that growth at chronic elevated ozone concentration primed the antioxidant system. Growth at high carbon dioxide concentration decreased the antioxidant capacity of leaves, increased the response of the existing antioxidant enzymes to an acute oxidative stress, but dampened and delayed the transcriptional response, suggesting an entirely different regulation of the antioxidant system. Third, I tested the findings from the controlled environment study in a field setting by investigating the response of the soybean antioxidant system to growth at elevated carbon dioxide concentration, chronic elevated ozone concentration and the combination of elevated carbon dioxide concentration and elevated ozone concentration. In this study, I confirmed that growth at elevated carbon dioxide concentration decreased specific components of antioxidant metabolism in the field. I also verified that increasing ozone concentration is highly correlated with increases in the metabolic and genomic components of antioxidant metabolism, regardless of carbon dioxide concentration environment, but that the response to increasing ozone concentration was dampened at elevated carbon dioxide concentration. In addition, I found evidence suggesting an up regulation of respiratory metabolism at higher ozone concentration, which would supply energy and carbon for detoxification and repair of cellular damage. These results consistently support the conclusion that growth at elevated carbon dioxide concentration decreases antioxidant metabolism while growth at elevated ozone concentration increases antioxidant metabolism.

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Trinitrotoluene in the purification step (TNT) produced in industries, are carried out two washes at the end of the process. The first wash is done with vaporized water, which originates from the first effluent called yellow water, then the second washing with the use of sodium sulfite is performed (Na2SO3), generating a second effluent red water. This study aimed to study the individual effects, as well as the association of heterogeneous photocatalysis using TiO2 and biological treatment in air lift reactor using activated sludge (bacterial biomass) for the remediation of wastewater contaminated with nitroaromatic compounds in order to reduce toxicity and adjust the legal parameters according to regulatory agencies for disposal in waterways. The photocatalytic treatment was conducted by factorial design obtaining the best reaction conditions (pH 6.5 and concentration of TiO2 0.1 gL-1), with best results obtained at 360 minutes of reaction, reducing the absorbance 97.00%, 94.20% of the chemical oxygen demand (COD), 67.70% of total phenols, as well as a total reduction of observed peaks and assigned to nitroaromatic compounds by high-performance liquid chromatography. In the biological treatment, there was a 53.40% reduction in absorbance at 275 nm 10.00% 36.00% COD and total phenols in a short time (3 days), while for extended periods (48 days) there was an antagonistic influence on the results so that was the elevation of these parameters (COD and total phenols) instead of reducing. Chromatographic analysis confirmed the effectiveness of the biological degradation by reducing the peaks corresponding to compounds DNT and TNT. The Association of photocatalytic and biological treatments decreased results in the order of 91.10% absorbance, 70.26% of total phenols and 88.87% of COD. While the combination of biological and photocatalytic treatments generated relatively lower efficiencies, with 77.30% of absorbance reduction, 62.10% reduction of total phenols and a decrease of 87.00% of COD. In general, when comparing the chemical and biological processes in isolation, the photocatalytic treatment showed the best results. However, comparing the results of isolation and established associations, the association biological x photocatalysis showed more promising results in the treatment of red water effluent.

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The long-term adverse effects on health associated with air pollution exposure can be estimated using either cohort or spatio-temporal ecological designs. In a cohort study, the health status of a cohort of people are assessed periodically over a number of years, and then related to estimated ambient pollution concentrations in the cities in which they live. However, such cohort studies are expensive and time consuming to implement, due to the long-term follow up required for the cohort. Therefore, spatio-temporal ecological studies are also being used to estimate the long-term health effects of air pollution as they are easy to implement due to the routine availability of the required data. Spatio-temporal ecological studies estimate the health impact of air pollution by utilising geographical and temporal contrasts in air pollution and disease risk across $n$ contiguous small-areas, such as census tracts or electoral wards, for multiple time periods. The disease data are counts of the numbers of disease cases occurring in each areal unit and time period, and thus Poisson log-linear models are typically used for the analysis. The linear predictor includes pollutant concentrations and known confounders such as socio-economic deprivation. However, as the disease data typically contain residual spatial or spatio-temporal autocorrelation after the covariate effects have been accounted for, these known covariates are augmented by a set of random effects. One key problem in these studies is estimating spatially representative pollution concentrations in each areal which are typically estimated by applying Kriging to data from a sparse monitoring network, or by computing averages over modelled concentrations (grid level) from an atmospheric dispersion model. The aim of this thesis is to investigate the health effects of long-term exposure to Nitrogen Dioxide (NO2) and Particular matter (PM10) in mainland Scotland, UK. In order to have an initial impression about the air pollution health effects in mainland Scotland, chapter 3 presents a standard epidemiological study using a benchmark method. The remaining main chapters (4, 5, 6) cover the main methodological focus in this thesis which has been threefold: (i) how to better estimate pollution by developing a multivariate spatio-temporal fusion model that relates monitored and modelled pollution data over space, time and pollutant; (ii) how to simultaneously estimate the joint effects of multiple pollutants; and (iii) how to allow for the uncertainty in the estimated pollution concentrations when estimating their health effects. Specifically, chapters 4 and 5 are developed to achieve (i), while chapter 6 focuses on (ii) and (iii). In chapter 4, I propose an integrated model for estimating the long-term health effects of NO2, that fuses modelled and measured pollution data to provide improved predictions of areal level pollution concentrations and hence health effects. The air pollution fusion model proposed is a Bayesian space-time linear regression model for relating the measured concentrations to the modelled concentrations for a single pollutant, whilst allowing for additional covariate information such as site type (e.g. roadside, rural, etc) and temperature. However, it is known that some pollutants might be correlated because they may be generated by common processes or be driven by similar factors such as meteorology. The correlation between pollutants can help to predict one pollutant by borrowing strength from the others. Therefore, in chapter 5, I propose a multi-pollutant model which is a multivariate spatio-temporal fusion model that extends the single pollutant model in chapter 4, which relates monitored and modelled pollution data over space, time and pollutant to predict pollution across mainland Scotland. Considering that we are exposed to multiple pollutants simultaneously because the air we breathe contains a complex mixture of particle and gas phase pollutants, the health effects of exposure to multiple pollutants have been investigated in chapter 6. Therefore, this is a natural extension to the single pollutant health effects in chapter 4. Given NO2 and PM10 are highly correlated (multicollinearity issue) in my data, I first propose a temporally-varying linear model to regress one pollutant (e.g. NO2) against another (e.g. PM10) and then use the residuals in the disease model as well as PM10, thus investigating the health effects of exposure to both pollutants simultaneously. Another issue considered in chapter 6 is to allow for the uncertainty in the estimated pollution concentrations when estimating their health effects. There are in total four approaches being developed to adjust the exposure uncertainty. Finally, chapter 7 summarises the work contained within this thesis and discusses the implications for future research.

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A comprehensive environmental monitoring program was conducted in the Ojo Guareña cave system (Spain), one of the longest cave systems in Europe, to assess the magnitude of the spatiotemporal changes in carbon dioxide gas (CO2) in the cave–soil–atmosphere profile. The key climate-driven processes involved in gas exchange, primarily gas diffusion and cave ventilation due to advective forces, were characterized. The spatial distributions of both processes were described through measurements of CO2 and its carbon isotopic signal (δ13C[CO2]) from exterior, soil and cave air samples analyzed by cavity ring-down spectroscopy (CRDS). The trigger mechanisms of air advection (temperature or air density differences or barometric imbalances) were controlled by continuous logging systems. Radon monitoring was also used to characterize the changing airflow that results in a predictable seasonal or daily pattern of CO2 concentrations and its carbon isotopic signal. Large daily oscillations of CO2 levels, ranging from 680 to 1900 ppm day−1 on average, were registered during the daily oscillations of the exterior air temperature around the cave air temperature. These daily variations in CO2 concentration were unobservable once the outside air temperature was continuously below the cave temperature and a prevailing advective-renewal of cave air was established, such that the daily-averaged concentrations of CO2 reached minimum values close to atmospheric background. The daily pulses of CO2 and other tracer gases such as radon (222Rn) were smoothed in the inner cave locations, where fluctuation of both gases was primarily correlated with medium-term changes in air pressure. A pooled analysis of these data provided evidence that atmospheric air that is inhaled into dynamically ventilated caves can then return to the lower troposphere as CO2-rich cave air.

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The project goal was to determine plant operations and maintenance worker’s level of exposure to mercury during routine and non-routine (i.e. turnarounds and inspections) maintenance events in eight gas processing plants. The project team prepared sampling and analysis plans designed to each plant’s process design and scheduled maintenance events. Occupational exposure sampling and monitoring efforts were focused on the measurement of mercury vapor concentration in worker breathing zone air during specific maintenance events including: pipe scrapping, process filter replacement, and process vessel inspection. Similar exposure groups were identified and worker breathing zone and ambient air samples were collected and analyzed for total mercury. Occupational exposure measurement techniques included portable field monitoring instruments, standard passive and active monitoring methods and an emerging passive absorption technology. Process sampling campaigns were focused on inlet gas streams, mercury removal unit outlets, treated gas, acid gas and sales gas. The results were used to identify process areas with increased potential for mercury exposure during maintenance events. Sampling methods used for the determination of total mercury in gas phase streams were based on the USEPA Methods 30B and EPA 1631 and EPA 1669. The results of four six-week long sampling campaigns have been evaluated and some conclusions and recommendations have been made. The author’s role in this project included the direction of all field phases of the project and the development and implementation of the sampling strategy. Additionally, the author participated in the development and implementation of the Quality Assurance Project Plan, Data Quality Objectives, and Similar Exposure Groups identification. All field generated data was reviewed by the author along with laboratory reports in order to generate conclusions and recommendations.

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In this thesis, a machine learning approach was used to develop a predictive model for residual methanol concentration in industrial formalin produced at the Akzo Nobel factory in Kristinehamn, Sweden. The MATLABTM computational environment supplemented with the Statistics and Machine LearningTM toolbox from the MathWorks were used to test various machine learning algorithms on the formalin production data from Akzo Nobel. As a result, the Gaussian Process Regression algorithm was found to provide the best results and was used to create the predictive model. The model was compiled to a stand-alone application with a graphical user interface using the MATLAB CompilerTM.