Combination Of UV Irradiation Research Articles

Ecotoxicity and rapid degradation of quaternary ammonium compounds (QACs) subjected to combined vacuum UV and UV-C treatment

Quaternary ammonium compounds (QACs) are active ingredients in a palette of commercially available disinfectants, sanitizers, and biocides. QACs are widely used because of their broad-spectrum antimicrobial properties but the ubiquitous uses have resulted in frequent detection in aquatic and terrestrial matrices including domestic wastewater, surface waters, urban soils and sediments. An increased domestic QACs consumption has increased the environmental occurrence, and investigation of mitigation methods and effects on non-target organisms are in demand. In this study, we examined the potential ecotoxicity of six QACs and investigated the effect of combined vacuum UV (185 nm) and UV-C (254 nm) irradiation (VUV/UVC) on degradation and mitigation of ecotoxicity of QACs. The study showed that combined VUV/UVC irradiation facilitated rapid degradation of benzalkonium chloride, benzethonium chloride, didecyldimethylammonium chloride, dodecyltrimethylammonium chloride, and hexadecyltrimethylammonium chloride. The estimated half-lives varied between 2 and 7 min, and degradation was affected by the initial QAC concentrations, the UV fluence, and the water matrix. The potential ecotoxicity of QACs and VUV/UVC treated QACs was examined using a battery of test organisms that included the luminescent bacterium Aliivibrio fischeri, the gram-negative and gram-positive bacteria Escherichiacoli and Enterococcus faecalis, the freshwater microalga Raphidocelis subcapitata, and the crustacean Daphia magna. The potential for trophic transfer of QACs was investigated in a simplified aquatic food web. Test organisms from different trophic levels were included to assess adverse effects of bioactive compounds in VUV/UVC treated samples including transformation products. The study showed that several QACs were highly toxic to aquatic test organisms with EC50 and/or EC20 values < 1 μM. VUV/UVC treatment of QACs resulted in substantial photolysis of the parent compounds and comprehensive mitigation of the ecotoxicity potential. VUV/UVC represent an attractive oxidation technology for abatement QACs in contaminated water because the process does not require addition of catalysts or precursors.

Photo-induced surface oxygen vacancies for effective promotion of the photocatalytic properties over hierarchical layered Bi2O2(OH)NO3

Semiconductor photocatalysts incorporating oxygen vacancies (OVs) have garnered significant attention and research efforts in the field of environmental remediation, but the methods for regulating oxygen vacancies are more demanding. In this work, a combination of UV irradiation and hydrothermal methods was used to create oxygen vacancy-rich Bi2O2(OH)NO3 (BON) photocatalysts, and the presence of oxygen vacancies was revealed by various experimental measurements and theoretical calculations, which regulate the band structure and optimizes the photogenerated carrier behavior of BON-30. The photocatalytic degradation performance of BON was subsequently investigated using the organic dye rhodamine B (RhB) under visible light illumination. The improved activity of BON-30 can be attributed to factors such as oxygen vacancies and reactive radicals O2–, which contribute to enhanced visible light absorption, narrowed band gap and reduced photoelectron-hole complexation ability. In addition, the stability of this photocatalyst shows great potential for application. This strategy provides a simple way to explore more efficient photocatalysts for environmental remediation.

Microscopic Analysis of Degraded Living Hinges of Polypropylene Aerial Cable Closure

Living hinges of polypropylene aerial cable closures that had been field-aged for eight years were analyzed in detail. Severe degradation including deep cracking was observed in the hinge central section, which had been subjected to UV light in the outdoor environment and repetitive sharp bending cycles during maintenance. On the other hand, the degradation of the other section was limited to within 10μm from the top surface. A repetitive bending cycle test alone did not reproduce the severe degradation. It was concluded that synergistic effects of solar UV irradiation and repetitive bending stress generated the severe degradation at the hinge section. Micro-cracks initially generated on the UV-degraded brittle top surface were the initial points of major cracks leading to breakage. Microscopic observations revealed craze structures around the major cracks. The crazes, caused by repetitive shear stress during the hinge-bending operations, were considered to be major routes for crack propagation. A test combining UV irradiation and repetitive sharp bending cycles on unused hinge specimens supported the crack generation and propagation mechanism.

Combining UV Irradiation and Alkaline Deacetylation to Obtain Vitamin D- and Chitosan-Enriched Fractions from Shiitake Mushrooms (Lentinula edodes)

Shiitake mushrooms (Lentinula edodes) contain compounds with hypocholesterolemic and immune-modulatory activities such as ergosterol and chitin that can be partially transformed into vitamin D and chitosan to yield extracts with enhanced bioactivities. A method was optimized to increase vitamin D2 levels by irradiating a non-soluble fraction obtained from shiitake mushrooms during 1 h with UV-light (254 nm) at 50 °C in methanol. After 1 h, almost all of the ergosterol was transformed into vitamin D2. The conversion ratio can be simply adjusted by reducing the irradiation time. A deacetylation treatment with 50% NaOH for 24 h at 95 °C was needed to generate chitosan and other water-soluble lower molecular weight derivatives from chitin. To obtain an extract enriched in both compounds, the defined methods can be combined, but the extracts should be firstly deacetylated and later irradiated. In this order, an extract is obtained containing vitamin D2 (4.65 mg/g) and chitosan (2.83%).

Aflatoxin Occurrence, Contamination, Detection, and Decontamination with Special Emphasis on Coconut Oil: A Review

Purpose: Coconut oil is one of the commonest and profusely used plant oils in Asian cuisine. Many studies are being carried out aiming at preventing/eliminating potential aflatoxin contamination of the oil or its products along the value chain. The present review analytically provides an overview of aflatoxin occurrence, contamination, detection, and decontamination of vegetable oils with special emphasis on coconut oil. Research Method: Findings and conclusions of studies related to aflatoxins, that are published in authentic sources were reviewed and presented in a chronological manner. Based on the information, current detection and decontamination methods for aflatoxins in edible plant oils were demonstrated. Findings: Complete decontamination of aflatoxins from edible oils seemed impossible, but reducing the accumulated concentrations below the permissible levels seemed possible. The use of chemical agents like alkalis, the most commonly practiced method on a commercial scale, adversely affects human health and the environment. UV irradiation is a promising physical decontamination method of oil with aflatoxins and combining UV irradiation with other potential methods such as the use of adsorbents showed an enhanced efficacy. However, further studies are required to ensure the effective and safe use of biological methods in aflatoxin-contaminated edible oils. Research Limitations: Research gaps in the application of biological decontamination methods in edible oils especially in coconut oil were found. Originality/ Value: This paper critically and aimfully analyzes the relevant information with a view to find gaps thereby showing new directions for applied research to assess nutritional, sensory, and quality attributes in the oils and value-added products, subjected to biological treatments.

Attenuation of toxicity and occurrence of degradation products of the fungicide tebuconazole after combined vacuum UV and UVC treatment of drinking water

Antifungal azoles are the most frequently used fungicides worldwide and occur as active ingredients in many antifungal pharmaceuticals, biocides, and pesticides. Azole fungicides are frequent environmental contaminants and can affect the quality of surface waters, groundwater, and drinking water. This study examined the potential of combined vacuum UV (185 nm) and UVC (254 nm) irradiation (VUV/UVC) of the azole fungicide tebuconazole and the transformation product 1,2,4-trizole on degradation and changes in ecotoxicity. In vivo ecotoxicity was examined before and after UV treatment using bioassays with test organisms from different trophic levels to integrate changes in biological effect of the parent compound and the degradation products. The test battery included the luminescent bacterium Aliivibrio fischeri, the Gram-positive bacterium Bacillus subtilis, the fungus Fusarium graminearum, the green microalga Raphidocelis subcapitata, and the crustacean Daphnia magna. The combined VUV/UVC treatment of tebuconazole in drinking water efficiently degraded the parent compound at the µg/L-mg/L level and resulted in transformation products with lower toxicity than the parent compound. A direct positive correlation was observed between the applied UV dose (fluence, J/cm2), the disappearance of tebuconazole, and the decrease in ecotoxicity. The combined VUV/UVC process does not require addition of supplementary oxidants or catalysts and our study suggests that VUV/UVC-mediated photolysis of azole fungicides in water can decrease the overall toxicity and represent a potentially environmentally friendly treatment method.

(Invited) Molecular Chemistry to Achieve Large Photoluminescence Enhancement in Transition Metal Dichalcogenides

I will focus on the following two topics along with the title; (1) the mechanism of the strong photoluminescence (PL) from monolayer (1L) transition metal dichalcogenides (TMDCs) by the superacid molecular treatment (Ref1), and (2) the unusual PL enhancement from bilayer (2L) TMDC (Ref.2).A direct band gap nature in semiconducting materials is a fascinating character for optical devices due to the strong absorption of photons and their luminescence properties. Monolayer TMDCs are known as direct band gap semiconductors, and a wide range of applications have been explored; however, some TMDCs, such as a representative MoS2, are known as a poor optical property. The PL quantum yield (QY) is less than several percent. Recently, superacid molecular treatment was demonstrated and achieved very strong PL; the mechanism is still in debate. In another case, bilayer (2L) TMDCs show an indirect band gap, and the PL intensity of them are usually very poor. Here, I will show our recent advancements on these topics about achieving strong PL from both 1L and 2L TMDCs. In detail, I will discuss (1) the mechanism of superacid treatment for monolayer MoS2 to achieve strong PL(Ref.1), and (2) strong PL enhancement in bilayer MoS2 by using superacid treatment with a combination of UV irradiation(Ref.2).Ref.1: Y. Yamada, et al. "Photoactivation of Strong Photoluminescence in Superacid-Treated Monolayer Molybdenum Disulfide", ACS Appl. Mater. Interfaces, 2020, 12, 36496–36504.Ref.2: Y. Yamada, et al. "Strong Photoluminescence Enhancement from Bilayer Molybdenum Disulfide via the Combination of UV-irradiation and Superacid Molecular Treatment", Applied Science 2021, in press.

Combined UV-irradiation and pyrolysis-GC/MS approach for evaluating the deterioration behavior of ethylene vinyl acetate

Ethylene vinyl acetate (EVA), commonly used to encapsulate photovoltaic (PV) modules, deteriorates on prolonged exposure to sunlight. In this work, fresh and deteriorated EVA samples prepared by UV irradiation (500 W m−2) over different periods (0–168 h) are characterized by conventional elemental analysis, microscopic observations, Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetry. To the best of our knowledge, this is the first work to employ pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and micro-UV irradiation combined Py-GC/MS (UV/Py-GC/MS) to investigate the deterioration behavior of EVA, using in-situ identification of gases liberated during UV irradiation, such as H2O, CO2, ketones, acetic acid, and lactones. In addition, the deterioration of the thermal stability on aging is confirmed using evolved gas analysis-mass spectrometry (EGA-MS). UV/Py-GC/MS revealed that acetaldehyde, acetone, acetic acid, γ-butyrolactone, succinic anhydride, and cyclobutanone are produced during UV irradiation. In addition, Py-GC/MS identified cyclopentanone, citraconic anhydride, γ-valerolactone, and cyclobutanone from the UV deteriorated EVA samples, which suggested the presence of ketone and lactone structures in the deteriorated EVA. This work establishes the combined usage of UV irradiation and Py-GC/MS as a promising method to investigate UV deterioration behavior in greater detail. These findings may contribute to a superior understanding of the breakdown of PV modules by the deterioration of EVA, and lead to the development of UV-resistant encapsulating materials.

Strong Photoluminescence Enhancement from Bilayer Molybdenum Disulfide via the Combination of UV Irradiation and Superacid Molecular Treatment

A direct band gap nature in semiconducting materials makes them useful for optical devices due to the strong absorption of photons and their luminescence properties. Monolayer transition metal dichalcogenides (TMDCs) have received significant attention as direct band gap semiconductors and a platform for optical applications and physics. However, bilayer or thicker layered samples exhibit an indirect band gap. Here, we propose a method that converts the indirect band gap nature of bilayer MoS2, one of the representative TMDCs, to a direct band gap nature and enhances the photoluminescence (PL) intensity of bilayer MoS2 dramatically. The procedure combines UV irradiation with superacid molecular treatment on bilayer MoS2. UV irradiation induces the conversion of the PL property with an indirect band gap to a direct band gap situation in bilayer MoS2 when the interaction between the top and bottom layers is weakened by a sort of misalignment between them. Furthermore, the additional post-superacid treatment dramatically enhances the PL intensity of bilayer MoS2 by a factor of 700×. However, this procedure is not effective for a conventional bilayer sample, which shows no PL enhancement. From these results, the separated top layer would show a strong PL from the superacid treatment. The monolayer-like top layer is physically separated from the substrate by the intermediate bottom MoS2 layer, and this situation would be preferable for achieving a strong PL intensity. This finding will be useful for controlling the optoelectronic properties of thick TMDCs and the demonstration of high-performance optoelectronic devices.

Effectiveness of decontamination protocols when analyzing ancient DNA preserved in dental calculus

Ancient DNA analysis of human oral microbial communities within calcified dental plaque (calculus) has revealed key insights into human health, paleodemography, and cultural behaviors. However, contamination imposes a major concern for paleomicrobiological samples due to their low endogenous DNA content and exposure to environmental sources, calling into question some published results. Decontamination protocols (e.g. an ethylenediaminetetraacetic acid (EDTA) pre-digestion or ultraviolet radiation (UV) and 5% sodium hypochlorite immersion treatments) aim to minimize the exogenous content of the outer surface of ancient calculus samples prior to DNA extraction. While these protocols are widely used, no one has systematically compared them in ancient dental calculus. Here, we compare untreated dental calculus samples to samples from the same site treated with four previously published decontamination protocols: a UV only treatment; a 5% sodium hypochlorite immersion treatment; a pre-digestion in EDTA treatment; and a combined UV irradiation and 5% sodium hypochlorite immersion treatment. We examine their efficacy in ancient oral microbiota recovery by applying 16S rRNA gene amplicon and shotgun sequencing, identifying ancient oral microbiota, as well as soil and skin contaminant species. Overall, the EDTA pre-digestion and a combined UV irradiation and 5% sodium hypochlorite immersion treatment were both effective at reducing the proportion of environmental taxa and increasing oral taxa in comparison to untreated samples. This research highlights the importance of using decontamination procedures during ancient DNA analysis of dental calculus to reduce contaminant DNA.

Performance Evaluation of PES-ZnO Nanohybrid using a Combination of UV Irradiation and Cross-linking for Wastewater Treatment of the Rubber Industry to Clean Water

Polyethersulfone (PES) membrane can be easily fouled during wastewater treatment as it is slightly hydrophobic. Consequently, several modifications are required to improve membrane surface properties to avoid membrane fouling. UV irradiation and cross-linked polyvinyl alcohol coating on nanohybrid membranes were performed in this study, and PES was combined with ZnO nanoparticles as an inorganic additive. Also, the PES-ZnO nanohybrid membrane was treated under the UV irradiation for a specific exposure time followed with membrane coating using polyvinyl alcohol (PVA) by the dip-coating method. Then, rubber wastewater filtration tests were performed using a cross-flow filtration system. The results revealed that the modifications significantly improved permeability and selectivity. As the duration of the UV irradiation increased, the higher mean flux value increased up to 14.55 L.m-2.h-1, but it was sacrificing the rejection efficiency. While the PVA coating decreased the water permeability up to 10.5 L.m-2.h-1 and increased the PVA concentration, the contaminant rejection increased up to 82%. The best membrane composition based on this study consisted of 17 wt.% of PES, 1 wt.% of ZnO nanoparticles, 5 wt.% Polyethylene glycol (PEG), 2 minutes UV irradiation, and 3% PVA coating.

Enhancement of nanohybrid PES-nanosilica performance for CO2/CH4 separation through combined UV irradiation and thermal annealing treatments

Energy supply has been one of the world’s main problems. Thus, the development of new energy and renewable energy resources can be a promising solution. As one of the promising energies from biomass is bio-methane obtained from biogas purification. Membrane separation is a potential technology for biogas purification processes. However, it still needs further improvements. The current study is to investigate the effect of UV irradiation and thermal annealing of nanohybrid PES-nano silica membrane and the effect of combined UV irradiation and thermal annealing on the CO2/CH4 separation performance. The nano hybrid PES-nanosilica membrane was fabricated by preparing the dope solution containing PES, NMP, and nanosilica. The membrane was casted using NIPS method and subsequently modified with UV and thermal annealing treatments. UV irradiation and thermal annealing treatments increased the selectivity and permeability of membrane in CO2/CH4 gas separation. Indeed, as the UV irradiation and thermal annealing time span increased, the membrane performance for CO2/CH4 separation also improved. The treatments modified nano hybrid membrane’s layer density and finally improved the membrane separation properties. The combination of UV irradiation and thermal annealing treatments significantly enhanced nanohybrid PES-nano silica performance for CO2/CH4 separation.

Low-temperature chemical fabrication of WO3 gasochromic switchable films: a comparative study of Pd and Pt nanoparticles dispersed WO3 films based on their structural and chemical properties

Pd nanoparticles dispersed WO3 (Pd-WO3) gasochromic switchable films were prepared using our method combining UV irradiation and H2 gas flow at room temperature. Structural, chemical and optical switching properties of the films were evaluated and compared with those of the Pt-WO3 films prepared using the same method. It was found that the distribution of catalysts in the Pd-WO3 films was different from that in the Pt-WO3 films. The Pd-WO3 films exhibited large difference in optical transmittance in their colored and bleached states, which was similar to that of the Pt-WO3 films. However, the coloring of the Pd-WO3 films by H2 gas was a little slower than that of the Pt-WO3 films, although the bleaching of these films by air was similarly fast. It was speculated that the difference in the gasochromic properties between the Pd-WO3 and the Pt-WO3 films is likely due to the difference in the distributions of catalysts between the Pd-WO3 and the Pt-WO3 films.

Effects on inactivation of Tetraselmis suecica following treatment by KBAL: a UV-based ballast water treatment system with an in-line vacuum drop

The transfer of non-native, possibly invasive species in ship’s ballast water is of global concern, and the International Maritime Organization and U.S. Coast Guard have adopted standards to minimize the environmental footprint caused by the maritime industry. In this study, seawater spiked with the phytoplankter Tetraselmis suecica, was treated with Knutsen Ballast Water Treatment Technology (KBAL), combining UV irradiation with an in-line vacuum drop. The test water was subsequently incubated in dark tanks, simulating what happens onboard a ship, where ballast water is treated at intake, stored in dark ballast tanks during the voyage, and then treated at discharge. Our results of the test water treated with KBAL and stored 5 days in the dark showed < 10 viable T. suecica cells ml−1 when assessing reproduction and > 10 living cells ml−1 when assessing metabolism. This highlights the challenge UV-based BWTS can encounter when meeting testing regimes assessing different characteristics of life. By comparing the effects caused by KBAL treatment with effects caused by UV irradiation only, we demonstrated that the pressure/vacuum technology seems to improve the disinfection effect. In addition, our investigations point out possible challenges with in situ conditions getting representative ballast water samples.

A Carotenoid- and Poly-β-Hydroxybutyrate-Free Mutant Strain of Sphingomonas elodea ATCC 31461 for the Commercial Production of Gellan.

Gellan gum is a microbial exopolysaccharide, produced after aerobic fermentation using the Gram-negative bacterium strain Sphingomonas elodea ATCC 31461. Due to its unique structure and excellent physical characteristics, gellan gum has a broad range of applications in food, pharmaceutical, and other industries where it is used for stabilizing, emulsifying, thickening, and suspending. During the fermentative production of gellan, strain ATCC 31461 also accumulates large amounts of the metabolic by-products yellow carotenoid pigments and poly-β-hydroxybutyrate (PHB), which is decreasing the gellan production and increasing processing costs. A pigment PHB-free mutant was obtained by knocking out the phytoene desaturase gene (crtI) in the carotenoid biosynthetic pathway and the phaC gene, encoding a PHB synthase for the polymerization of PHB. Unfortunately, the double gene knockout mutant produced only 0.56 g liter-1 gellan. Furthermore, blocking PHB and carotenoid synthesis resulted in the accumulation of pyruvate, which reduced gellan production. To elevate gellan production, combined UV irradiation and ethyl methanesulfonate (EMS) mutagenesis treatment were used. A mutant strain with the same level of pyruvate as that of the wild-type strain and higher gellan production was isolated (1.35 g liter-1, 132.8% higher than the double gene knockout mutant and 14.4% higher than the wild-type strain ATCC 31461). In addition, a new gellan gum recovery method based on the new mutant strain was investigated, in which only 30% isopropanol was required, which is twice for the wild-type strains, and the performance of the final product was improved. Thus, the mutant strain could be an ideal strain for the commercial production of gellan.IMPORTANCE A carotenoid- and PHB-free double gene knockout strain mutant was constructed to simplify the purification steps normally involved in gellan production. However, the production of gellan gum was unexpectedly reduced. A mutant with 14.4% higher gellan production than that of the wild-type strain was obtained and isolated after employing UV and EMS combined mutagenesis. Based on this high-yield and low-impurity-producing mutant, a new recovery method requiring less organic solvent and fewer operating steps was developed. This method will effectively reduce the production costs and improve the economic benefits of large-scale gellan production.

Chemical behaviors and toxic effects of ametryn during the UV/chlorine process

Ametryn (AMT), one of the most widely used herbicides in agriculture, has been frequently detected as a micropollutant in many aquatic environments. AMT residue not only pollutes water but also acts as a precursor for the production of disinfection by-products (DBPs). This study systematically investigated the fate of AMT during the UV/chlorine process. It was observed that the combination of UV irradiation and chlorination degraded AMT synergistically. The results of the radical quenching experiments suggested that AMT degradation by the UV/chlorine process involved the participation of UV photolysis, hydroxyl radical (OH) reactions, and reactive chlorine species (RCS) reactions, which accounted for 45.4%, 36.4%, and 14.5% of the degradation, respectively. Moreover, we found that Cl– 2 was an important reactive radical for AMT degradation. The chlorine dose, pH, coexisting anions (Cl− and HCO3−), and natural organic matter (NOM) were found to affect AMT degradation during the UV/chlorine process. Nineteen predominant intermediates/products of AMT degradation during UV/chlorine process were identified, including atrazine. Moreover, the corresponding transformation pathways were proposed, including electron transfer, bond cleavage (C–S, C–N), radical (OH, Cl and Cl– 2) reactions, and subsequent hydroxylation. The toxicity tests with Vibrio fischeri on AMT degradation suggested that more DBPs were generated by UV/chlorine-treated AMT, which possessed higher acute toxicity than AMT did. Although the UV/chlorine process evidently promoted the AMT degradation, optimization of process parameters may reduce the DBP production and merits further investigation.

Degradation of Styrene from Waste Gas Stream by Advanced Oxidation Processes

Waste‐air treatment is experimentally investigated by advanced oxidation processes utilizing UV irradiation combined with ozone and hydrogen peroxide. The effect of operating parameters, such as an initial concentration of styrene and flow rate of gas, on the removal of styrene is studied in a photochemical pilot plant unit. The conversion of styrene decreases with an increasing initial styrene concentration and with a decreasing retention time (higher flow rate) of waste gas. The highest conversion of styrene (87%) is achieved under lower initial styrene concentration (100 ppm) and lower flow rate (42 m3 h−1). The energy per order is also calculated for the advanced oxidation process. Electrical energy per order is calculated for all the experimental conditions and it was found that the energy consumption is of about 0.070 kWh m−3 per order, for the 87% styrene removal at 100 ppm of initial styrene concentration and 42 m3 h−1 flow rate. The combination of UV irradiation and ozone is significantly more efficient with lower electrical energy need per order in comparison with combination of UV irradiation and hydrogen peroxide. Therefore, the advanced oxidation process represents a promising treatment technology for the management of waste‐air, and the pilot plant unit designed for high flow rates of waste‐gas streams is suitable for an industrial use.

Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications

The present work focuses on the treatment of VOC emissions from industrial processes, since they represent a very severe environmental hazard. For removing the VOC, an AOP (Advanced Oxidation Process) stage based on UV light and ozone was considered, analyzing the methods for the unit scale-up. An innovative CFD (Computational Fluid Dynamics) model, combining UV irradiation, reaction kinetics and fluid dynamics, describing the behavior of UV reactors in the laboratory scale, was developed. This model was verified against experimental results, displaying good agreement. Therefore, we concluded the CFD model could adequately describe relevant features regarding the performance of UV reactors. After analyzing the laboratory reactors, two designed and scaled up prototypes, were simulated using the CFD model. While the first prototype has a standard lamps configuration, the second presents an innovative lamps distribution. As for the laboratory cases, the most relevant features in terms of irradiation and reaction were described for the prototypes, comparing their performance. We evaluated both the overall VOC conversion and VOC conversion per UV lamp, analyzing the energy efficiency of each configuration with adequately accuracy. Therefore, we conclude the developed CFD model to be an important tool for reactor scale-up as a result of the good prediction of experimental results and the accurate description of the governing phenomena. By using the developed model, the scale-up process of UV reactors can be quickly improved, by screening various configurations with the simulator before testing them, saving significant time and effort in the development of full-scale reactors.

Pretreatment of Herbal, Tofu and Fertilizer Waste Using UV/Ozon Technique and Its Utilization for Spirulina sp Cultivation

The herbal, tofu and fertilizer industries contribute considerable waste to the environment. The waste contains COD and organic substances which should be reduced before it is discharged to the environmental body. One of methods is by using Advanced Oxidation Processes (AOPs) degradation method. The process of AOPs in this study used a combination of UV irradiation and ozone to produce hydroxyl radicals. This study was aimed to investigate the degradation of Chemical Oxygen Demand (COD) by using AOP techniques and to evaluate the treated waste for microalgae growth. This research consists of two steps: (1) the initial COD degradation using UV-Ozon. (2) utilization of the treated waste for microalgae cultivation by combining a mixed nutrient of waste and 10 mg/L TSP, 10 mg/L Urea, 80mg/L NaHCO3. The results showed that the COD degraded by UV/Ozone follows the first order equation by k value of 0.082/day, 0.223/day and 0.436/day for tofu, herbal and fertilizer waste respectively. The growth rate of Spirulina cultivated in waste medium was in comparable with the one cultivated in control medium.

AKT inhibition impairs PCNA ubiquitylation and triggers synthetic lethality in homologous recombination-deficient cells submitted to replication stress

Translesion DNA synthesis (TLS) and homologous recombination (HR) cooperate during S-phase to safeguard replication forks integrity. Thus, the inhibition of TLS becomes a promising point of therapeutic intervention in HR-deficient cancers, where TLS impairment might trigger synthetic lethality (SL). The main limitation to test this hypothesis is the current lack of selective pharmacological inhibitors of TLS. Herein, we developed a miniaturized screening assay to identify inhibitors of PCNA ubiquitylation, a key post-translational modification required for efficient TLS activation. After screening a library of 627 kinase inhibitors, we found that targeting the pro-survival kinase AKT leads to strong impairment of PCNA ubiquitylation. Mechanistically, we found that AKT-mediated modulation of Proliferating Cell Nuclear Antigen (PCNA) ubiquitylation after UV requires the upstream activity of DNA PKcs, without affecting PCNA ubiquitylation levels in unperturbed cells. Moreover, we confirmed that persistent AKT inhibition blocks the recruitment of TLS polymerases to sites of DNA damage and impairs DNA replication forks processivity after UV irradiation, leading to increased DNA replication stress and cell death. Remarkably, when we compared the differential survival of HR-proficient vs HR-deficient cells, we found that the combination of UV irradiation and AKT inhibition leads to robust SL induction in HR-deficient cells. We link this phenotype to AKT ability to inhibit PCNA ubiquitylation, since the targeted knockdown of PCNA E3-ligase (RAD18) and a non-ubiquitylable (PCNA K164R) knock-in model recapitulate the observed SL induction. Collectively, this work identifies AKT as a novel regulator of PCNA ubiquitylation and provides the proof-of-concept of inhibiting TLS as a therapeutic approach to selectively kill HR-deficient cells submitted to replication stress.