Ultraviolet Modification Research Articles

Effect of chlorination and ultraviolet on the adsorption of pefloxacin on polystyrene and polyvinyl chloride

During the water treatment process, chlorination and ultraviolet (UV) sterilization can modify microplastics (MPs) and alter their physicochemical properties, causing various changes between MPs and other pollutants. In this study, the impact of chlorination and UV modification on the physicochemical properties of polystyrene (PS) and polyvinyl chloride (PVC) were investigated, and the adsorption behavior of pefloxacin (PEF) before and after modification was examined. The effect of pH, ionic strength, dissolved organic matter, heavy metal ions and other water environmental conditions on adsorption behavior was revealed. The results showed that PS had a higher adsorption capacity of PEF than PVC, and the modification increased the presence of O-containing functional groups in the MPs, thereby enhancing the adsorption capacity of both materials. Chlorination had a more significant impact on the physicochemical properties of MPs compared to UV irradiation within the same time period, leading to better adsorption performance of chlorination. The optimal pH for adsorption was found to be 6, and NaCl, sodium alginate and Cu2+ would inhibit adsorption to varying degrees, among which the inhibition caused by pH was the strongest. Chlorination and UV modification would weaken the inhibitory effect of environmental factors on the adsorption of PEF by MPs. The main mechanisms of adsorption involved electrostatic interaction and hydrogen bonding. The study clarified the effects of modification on the physicochemical properties of MPs, providing reference for subsequent biotoxicity analysis and environmental protection studies.

Effects of UV-modified biochar derived from phytoremediation residue on Cd bioavailability and uptake in Coriandrum sativum L. in a Cd-contaminated soil.

Biochar has been applied widely as an amendment in the remediation of contaminated soil to immobilize the heavy metals. However, the role of ultraviolet (UV) irradiation modified biochar derived from the residues of phytoremediation plants in the contaminated soil not investigated yet. In this study, the UV-modified biochars were obtained from Brassica napus L. and Lolium perenne L. by pyrolysis at 600 °C. They were applied in a pot experiment to investigate their effect on Cd bioavailability and uptake in Coriandrum sativum L. in a Cd-contaminated soil at four addition rate (0%, 0.2%, 0.4%, and 0.6%). The results showed that the Cd was effectively stabilized in the biochar with environmentally acceptable leaching toxicity. The specific surface area and carboxyl functional group of biochar were greatly increased after UV modification. The application of biochar progressively increased the soil pH and electrical conductivity (EC). Furthermore, the CaCl2-extractable Cd was significantly reduced by 18.4-51.4% with biochar amendments. The concentration of Cd in shoots and roots was significantly reduced by biochars. In conclusion, the UV-modified biochar obtained from phytoremediation residue could effectively deal with hazardous waste and repair Cd-contaminated soil.

UV Modified Epoxy for LED Encapsulant

Light Emitting Diode (LED) packaging is important for the protection and enhancement of light extraction efficiency in LED. The most commonly used encapsulant is epoxy resin, which is the annealing cured. Multilayer time delayed aging of the epoxy resin causes delamination during packaging process. Ultraviolet (UV) modification is introduced in the curing process of epoxy resin to enhance the curing process of the epoxy. In this paper, the samples tested are either modified with UV or vice versa. Differential Scanning Calorimeter (DSC) is used for the analysis of the sample. Six samples are tested. Data analysis is based on the heat of reactions between the mixed materials; either the process is exothermic or endothermic when the temperature changes. The reaction between the materials determines its ability to crosslink, viscosity and temperature control for the whole reaction.

НЕСТАБИЛЬНАЯ СТЕНОКАРДИЯ ИЛИ НЕСТАБИЛЬНЫЕ КОРОНАРНЫЕ СИНДРОМЫ?

Unstable angina pectoris (UA) is a variant of acute coronary syndrome without ST segment elevation (NSTEACS), which is characterized by the absence of biochemical criteria for myocardial damage, a change in the clinical picture of angina pectoris (an increase in the functional class of angina pectoris, the appearance of resting angina and a high probability of transformation of the process into myocardial infarction (MI). UA and the developed MI without ST segment elevation (NSTEMI) are not accompanied by the appearance of a pathological Q wave and are characterized by a general complex pathogenesis associated with progressive atherosclerosis, a non-occlusive thrombus in the area of erosion or rupture of an atherosclerotic plaque, vasospasm, coronary microcirculatory dysfunction or other causes of imbalance between oxygen intake and oxygen consumption resulting in myocardial ischemia, and are distinguished by increased levels of myocardial necrosis in the blood in case of NSTEMI. It is difficult to differentiate UA and NSTEMI in the first hours of the development of the process when a decision is made on reperfusion technologies and drug therapy without laboratory, and in some cases, additional examination with visualization of the probable new loss of viable myocardium, therefore, the diagnosis and management of these two clinical conditions are usually considered in the same clinical recommendations. A fairly common point of view that the risk of death in UA is significantly lower and the patient is less in need of an intensive strategy than with verified NSTEMI, is controversial given the likely cases of sudden cardiac death of ischemic genesis at the prehospital stage and the difficulties of differential diagnosis of these clinical states. The factors contributing to diagnostic errors include severity of the patient's condition, a variety of clinical atypical manifestations and pathophysiological mechanisms of myocardial ischemia, the presence of comorbid pathology. The article discusses various mechanisms of the development of myocardial ischemia, diagnostic and therapeutic invasive and non-invasive technologies that improve the prognosis of patients with UA. The optimal management tactics of NSTEACS includes early diagnosis and risk stratification, emergency hospitalization, monitoring, the use of non-invasive and invasive strategies, including coronary angiography and revascularization, as well as emergency and long-term treatment aimed at preventing acute cardiovascular events taking into account the age, gender differences and comorbid pathology. A differentiated approach to the administration of emergency therapy is the key to improving the prognosis of this high-risk category of patients. Due to the lack of the possibility of using revascularizing technologies in patients with obstructive coronary disease, non-pharmacological technologies that positively affect microcirculation processes are likely to be used: exposure of the patient’s blood to an alternating magnetic field (extracorporeal autohemomagnetotherapy) or to ultraviolet optical radiation (ultraviolet blood modification). In view of the difficulty in identifying the mechanism of myocardial ischemia in each individual patient with UA and a high likelihood of combination of various pathophysiological factors, myocardium rescue should be in the focus of therapeutic intervention, which dictates the validity and utility of all the recommended and available methods of pharmacological and non-pharmacological therapy and revascularization to reduce the effects of myocardial ischemia.

The effect of ultraviolet modification of Acetobacter xylinum (CGMCC No. 7431) and the use of coconut milk on the yield and quality of bacterial cellulose

SummaryThis paper reports on the treatment of Acetobacter xylinum (CGMCC No. 7431) by ultraviolet (UV) to investigate the role of mutagenesis on the production of cellulose. When Acetobacter xylinum was treated at intervals of UV mutagenesis, the treatment times of 3 and 4 min formed more compact bacterial cellulose. The activation conditions, including the medium nutrients that affected the yield of bacterial cellulose, were investigated including the use of coconut milk. The optimal yield of bacterial cellulose was 43.91 ± 3.89 g L−1, which was 1.22 times higher than that obtained from the wild type without any treatment. The experimental results suggested that different UV factors could significantly affect the yield of bacterial cellulose. The resulting bacterial cellulose has a potential as a novel functional food material.

Characterization of ultraviolet-modified biochar from different feedstocks for enhanced removal of hexavalent chromium from water

Biochars produced from different feedstocks via pyrolytic carbonization and ultraviolet (UV) modification were used as alternative adsorbents for aqueous hexavalent chromium (Cr(VI)) remediation. Structural and morphological analysis showed that UV irradiation increased the surface area of biochar and added a large amount of oxygen-containing functional groups on the biochar's surface, resulting in about 2-5 times increase of Cr(VI) removing capacity (14.39-20.04 mg/g) compared to that of unmodified biochars (3.60-8.43 mg/g). The sorption ability among different feedstocks after modification was as follows: corn stack > sawdust > wheat straw. The adsorption kinetics and adsorption isotherm data agreed well with the pseudo-second-order model and Freundlich model, respectively. Experimental and modeling results suggested that the oxygen-containing functional groups and surface areas of biochars were notably increased after UV irradiation, which was mainly governed by surface complexation. X-ray photoelectron spectroscopy analysis showed that reduction occurred during Cr(VI) adsorption. In addition, UV irradiation significantly increased the concentration of dissolved organic matter (DOM) in biochars. The collected outcomes showed that UV-modified biochar was a good material for the removal of hexavalent chromium from aqueous medium. The excellent adsorption capacity, environmental-friendly and low cost properties made the novel material an auspicious candidate for environmental remediation.

UV modification of biochar for enhanced hexavalent chromium removal from aqueous solution.

This study was conducted to understand the effects of ultraviolet (UV) irradiation on the physicochemical properties and the hexavalent chromium (Cr(VI)) removal ability of biochar. Structural and morphological analysis showed that UV irradiation increased the specific surface area of biochar and added a large amount of oxygen-containing functional groups (e.g., carboxyl, lactonic, and hydroxyl) to biochar's surface. Batch sorption experimental results showed that UV-modified biochar (UVBC) produced at the pyrolysis temperature of 300°C, the irradiated time of 24h, and the irradiation distance of 40mm exhibited excellent Cr(VI) removal ability (from 1.11mg/g for BC to 20.04mg/g for UVBC, a 18.1-fold increase). The adsorption kinetics and adsorption isotherm data agreed well with the pseudo-second-order model and Freundlich model, respectively. Experimental and modeling results suggest that the oxygen-containing functional groups and specific surface areas of biochars were notably increased by UV irradiation, which enhanced Cr(VI) adsorption by surface complexation. X-ray photoelectron spectroscopy (XPS) analysis of UVBC before and after reaction with Cr(VI) showed that reduction occurred during Cr(VI) adsorption. The energy consumption of UV modification is 2.7MJ per gram of UVBC produced, which is comparable to that in activated carbon. The results showed that the method of UV modification of biochar is a very novel and effective method for the adsorption of Cr(VI) in solution.

Estimating Cloud and Aerosol UV Modification Factors Based on Spectral Measurement from the Brewer Spectrophotometer

Cloud and aerosol modification factors are investigated in the spectral range of ultraviolet (UV) to correct for cloud and aerosol extinction effects from clear sky irradiance. The cloud modification factor (CMF) and aerosol modification factor (AMF) are estimated using radiative transfer model (RTM) simulations and ground-based observations in Seoul, Korea. The modification factors show a spectral dependence within the spectral range of 300 to 360 nm, which is the range used to estimate erythemal UV. The CMF and AMF values are estimated with high spectral resolution with considerations of solar zenith angle (SZA), cloud/aerosol amount, and total ozone variation. From the simulation studies, the variation in the CMFs within the spectral range of 300–360 nm is estimated to be 0.031–0.055, which is twice as large as the decrease in CMFs resulting from a SZA increase of 10°. In addition, the CMFs estimated from observational data show significant spectral dependence, varying from 2.5% to 10.0%. Because of the small aerosol optical depth (AOD) value, however, the variation in the AMF calculated from simulations is estimated to be between 0.007 and 0.045, indicating lower spectral dependence than the CMF. Furthermore, the spectral difference in the AMF calculated from observational data is insignificant relative to the daily-averaged total ozone error and uncertainties related to the reference irradiance spectrum under aerosol-free conditions.

Effects of Ultraviolet Modification on Physicochemical Property and Adsorption Performance of Biochar

Effects of Ultraviolet Modification on Physicochemical Property and Adsorption Performance of Biochar

Ultraviolet modification of Chlamydomonas reinhardtii for carbon capture

Ultraviolet modification of Chlamydomonas reinhardtii for carbon capture Nikhil S Gopal,1 K Sudhakar2 1The Lawrenceville School, Lawrenceville, NJ, USA; 2Bioenergy Laboratory, Malauna Azad National Institute of Technology, Bhopal, India Purpose: Carbon dioxide (CO2) levels have been rising rapidly. Algae are single-cell organisms with highly efficient CO2 uptake mechanisms. Algae yield two to ten times more biomass versus terrestrial plants and can grow nearly anywhere. Large scale CO2 sequestration is not yet sustainable due to high amounts of nitrogen (N) and phosphate (P) needed to grow algae in media. Methods: Mutant strains of Chlamydomonas reinhardtii were created using ultraviolet light (2.2–3 K J/m2) and natural selection using media with 20%–80% lower N and P compared to standard Sueoka's high salt medium. Strains were selected based upon growth in media concentrations varying from 20% to 80% less N/P compared to control. Biomass was compared to wild-type control (CC-125) using direct counts, optical density dry weight, and mean doubling time. Results: Mean doubling time was 20 and 25 hours in the low N and N/P strains, respectively (vs 66 hours in control). Using direct counts, growth rates of mutant strains of low N and N/P cultures were not statistically different from control (P=0.37 and 0.70), respectively. Conclusion: Two new strains of algae, as well as wild-type control, were able to grow while using 20%–40% less N and P. Ultraviolet light-based modification of algae is an inexpensive and alternative option to genetic engineering techniques. This technique might make larger scale biosequestration possible. Keywords: biosequestration, ultraviolet, carbon sequestration, carbon capture, algae

Black holes and Thunderbolt singularities with Lifshitz scaling terms

We study a static, spherically symmetric and asymptotic flat spacetime, assuming the hypersurface orthogonal Einstein-aether theory with an ultraviolet modification motivated by the Horava-Lifshitz theory, which is composed of the $z=2$ Lifshitz scaling terms such as scalar combinations of a three-Ricci curvature and the acceleration of the aether field. For the case with the quartic term of the acceleration of the aether field, we obtain a two-parameter family of black hole solutions, which possess a regular universal horizon. While, if three-Ricci curvature squared term is joined in ultraviolet modification, we find a solution with a thunderbolt singularity such that the universal horizon turns to be a spacelike singularity.

UV modification of tire rubber for use in cementitious composites

The use of recycled rubber as a possible aggregate in concrete is known to result in a reduction of compressive and flexural strength. This paper summarises the results of initial studies on the effect of surface-treating rubber crumb (obtained from discarded tires) with ultraviolet (UV) radiation, with the aim of mitigating such losses. Investigation focussed on changing the surface energy, and therefore the bond strength, between cement and rubber. To identify the most effective UV wavelength for this purpose, a water retention test method was utilized, resulting in the selection of the UV-C wavelength range for treatment. Additionally, specimens containing rubber, treated for different time periods, were subjected to flexural testing. As expected, the addition of untreated crumb rubber resulted in a degradation of flexural strength, however exposure to UV-C generated, at best, values only 6% weaker than those of rubberless specimens, indicating the benefits of the investigated surface treatment.

Ultraviolet irradiation of diacetylenic liposomes as a strategy to improve size stability and to alter protein binding without cytotoxicity enhancement

Membrane-modification effects, induced by ultraviolet (UV) irradiation in diacetylenic liposomes, were analyzed upon contact with cells, biological membranes, and proteins. Liposomes formulated with mixtures of unsaturated 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine and saturated 1,2-dimyristoyl-sn-glycero-3-phosphocholine, in a 1:1 molar ratio, were compared with those that were UV-irradiated and analyzed in several aspects. Membrane polymerization inherence on size stability was studied as well as its impact on mitochondrial and microsomal membrane peroxidation induction, hemolytic activity, and cell viability. Moreover, in order to gain insight about the possible irradiation effect on interfacial membrane properties, interaction with bovine serum albumin (BSA), lysozyme (Lyso), and apolipoprotein (apoA-I) was studied. Improved size stability was found for polymerized liposomes after a period of 30 days at 4°C. In addition, membrane irradiation had no marked effect on cell viability, hemolysis, or induction of microsomal and mitochondrial membrane peroxidation. Interfacial membrane characteristics were found to be altered after polymerization, since a differential protein binding for polymerized or nonpolymerized membranes was observed for BSA and Lyso, but not for apoA-I. The substantial contribution of this work is the finding that even when maintaining the same lipid composition, changes induced by UV irradiation are sufficient to increase size stability and establish differences in protein binding, in particular, reducing the amount of bound Lyso and BSA, without increasing formulation cytotoxicity. This work aimed at showing that the usage of diacetylenic lipids and UV modification of membrane interfacial properties should be strategies to be taken into consideration when designing new delivery systems.

Comment on “Strong coupling in extended Hořava–Lifshitz gravity” [Phys. Lett. B 685 (2010) 197

We show that, contrary to the claim made in arXiv:0911.1299, the extended Hořava gravity model proposed in arXiv:0909.3525 does not suffer from a strong coupling problem. By studying the observational constraints on the model we determine the bounds on the scale of the ultraviolet modification for which the proposal yields a phenomenologically viable, renormalizable and weakly coupled model of quantum gravity.

Fabrication of comb-drive micro-actuators based on UV lithography of SU-8 and electroless plating technique

Comb-drive microactuators are widely used in MEMS devices. Most of the comb-drive microactuators reported in MEMS field are made using fabrication technology with silicon as the structural material. Recent progress in ultra violet (UV) lithography of SU-8 has made it feasible to fabricate ultra high aspect ratio microstructures with excellent sidewall quality. In this paper, a research work on fabrication and metallization of high aspect ratio SU-8 polymer comb-drive microactuators was reported. The fabrication process combined multi-step and multi-layer UV lithography of SU-8 on a silicon substrate and copper electroless plating to selectively metallize the SU-8 microstructure. The selective electroless plating was achieved by using UV modification of the SU-8 microstructures and the careful control of the exposure dosage. Preliminary experimental results have proved the feasibility of the microactuator and the fabrication technology.

Complementary organic field effect transistors by ultraviolet dielectric interface modification

The realization of p- and n-type pentacene organic field effect transistors and an organic inverter stage is reported based on selective ultraviolet (UV) modification of the polymer dielectric in air. Apart from the UV radiation treatment, the device structures are identical. The achieved field effect carrier mobilities for both transistor types are ≈0.1cm2∕Vs. Similar performance data for both transistor types as well as an observed low current hysteresis qualify the UV treatment for organic complementary metal oxide semiconductor (O-CMOS) technology. The realized O-CMOS inverter exhibits stable operation below its supply voltage, as well as a gain of 17.

A late-accelerating universe with no dark energy—and a finite-temperature bigbang

Brane-world models offer the possibility of explaining the late acceleration of the universevia infra-red modifications to general relativity, rather than a dark energy field.However, one also expects ultra-violet modifications to general relativity, whenhigh-energy stringy effects in the early universe begin to grow. We generalize the DGPbrane-world model via an ultra-violet modification, in the form of a Gauss–Bonnet termin the bulk action. The combination of infra-red and ultra-violet modificationsproduces an intriguing cosmology. The DGP feature of late-time accelerationwithout dark energy is preserved, but there is an entirely new feature—there isno infinite-temperature big bang in the early universe. The universe starts withfinite density and pressure, from a ‘quiet’ and ‘sudden’ curvature singularity.

Blood Compatibility of Chitosan Immobilized on Poly(Ethylene Terephthalate) Surface Modified by Plasma and Ultraviolet Grafting

We report a study involving chitosan chains immobilized on poly (ethylene terephthalate) (PET) films by plasma and ultraviolet (UV) grafting modification. The surface structure of the modified PET is determined by means of attenuated total reflection Fourier transform infraed spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results show that the chains of chitosan are successfully grafted on the surface of PET. Platelet adhesion evaluation in vitro is conducted to examine the blood compatibility in vitro. Scanning electron microscopy (SEM) and optical microscopy reveal that the amounts of adhered, aggregated and morphologically changed platelets are reduced on the chitosan-immobilized PET films. The number of platelet adhered on the modified film is reduced by almost 48% compared to the amount of platelets on the untreated film. Our result thus shows that chitosan immobilized on the PET surface improves blood compatibility.

Low-volume discrete plasmapheresis in therapy of acute destructive lung and pleural diseases

Plasmapheresis with an exfusion volume of 1500–1600 ml has a pronounced detoxification effect in acute destructive lung and pleural diseases (ADLPDs) but can disturb volume balance and produce hypo- and dysproteinemia. The efficacy in pulmonary abscesses and gangrene was compared for standard discrete plasmapheresis (DPP, exfusion 1500–1600 ml) and low-volume DPP (LVDPP, exfusion 600–750 ml), which produces fewer volume-related complications. To increase the detoxification effect, LVDPP was combined with shortwave ultraviolet modification of erythrocytes to be reinfused (UME) in 29 patients or erythrocyte treatment with saline (ETS) in 21 patients or Hemodez (ETH) in 26 patients. The highest detoxification effect was observed for LVDPP-UME. The detoxification effect of LVDPP-ETH was comparable with that of DPP, and the effect of LVDPP-ETS was lower. LVDPP did not produce hypoproteinemia, while standard DPP aggravated it. LVDPP-UME and LVDPP-ETH normalized the proteinogram, while LVDPP-ETS did not improve the proteinogram nor aggravate dysproteinemia. LVDPP considerably decreased mortality and increased the rate of recovery with cicatrization of cavities. LVDPP-UME had the most pronounced effect in this respect, while the effect of LVDPP-ETS was lower. Thus, LVDPP-UME produced the best results in treating ADLPDs.

Effects of ultraviolet modification on the gating energetics of cyclic nucleotide-gated channels.

Middendorf et al. (Middendorf, T.R., R.W. Aldrich, and D.A. Baylor. 2000. J. Gen. Physiol. 116:227-252) showed that ultraviolet light decreases the current through cloned cyclic nucleotide-gated channels from bovine retina activated by high concentrations of cGMP. Here we probe the mechanism of the current reduction. The channels' open probability before irradiation, P(o)(0), determined the sign of the change in current amplitude that occurred upon irradiation. UV always decreased the current through channels with high initial open probabilities [P(o)(0) > 0.3]. Manipulations that promoted channel opening antagonized the current reduction by UV. In contrast, UV always increased the current through channels with low initial open probabilities [P(o)(0) < or = 0.02], and the magnitude of the current increase varied inversely with P(o)(0). The dual effects of UV on channel currents and the correlation of both effects with P(o)(0) suggest that the channels contain two distinct classes of UV target residues whose photochemical modification exerts opposing effects on channel gating. We present a simple model based on this idea that accounts quantitatively for the UV effects on the currents and provides estimates for the photochemical quantum yields and free energy costs of modifying the UV targets. Simulations indicate that UV modification may be used to produce and quantify large changes in channel gating energetics in regimes where the associated changes in open probability are not measurable by existing techniques.