UV-treated Samples Research Articles

Oxidative protein damage negatively affects protein-protein interaction: The case of KRAS-cRAF

Protein-protein interactions (PPIs) play crucial roles in cellular signaling, transmitting signals from the cell surface to its interior. One of the most important signaling cascades is the RAS-RAF-MEK-ERK pathway. This pathway is initiated by various upstream signaling reactions, including receptor tyrosine kinase (RTK) activation, and it controls many biological functions like cell proliferation, differentiation, and survival. Once RAS is activated, it binds RAF and relays the signal to downstream proteins. The RAS-binding domain (RBD) in RAF protein plays a crucial role in this process, facilitating the RAS-ERK pathway signaling.In this study, we explored the effect of oxidative stress induced by UV radiation on the KRAS-RBD interaction. Using the Split Intein-Mediated Protein Ligation (SIMPL) method, we assessed the impact of different UV doses on KRAS-RBD interactions and observed a disruption of this interaction at higher doses. UV-treated samples exhibited high levels of protein carbonylation, as detected by Oxime Blot and mass spectrometry (MS) analysis, indicating oxidative damage. The MS results provided detailed insights into specific carbonylation modifications on the KRAS protein.Our study demonstrates that protein oxidation and carbonylation can disrupt protein-protein interactions, specifically the KRAS/c-RAF interaction. These findings highlight the impact of oxidative stress on signaling pathways, such as those triggered by UV irradiation. A deeper understanding of these molecular changes may aid in developing therapies targeting diseases linked to oxidative stress, including cancer.

Effects of heat treatment and ultraviolet radiation on physicochemical, microbiological, and bioactive properties of shalgam juice.

Herein, we aimed to investigate the physicochemical, bioactive, microbial, and sensory properties of 5 different ultraviolet (UV) treatment conditions, varying in flow rate (1.5-2.5-3.5 L/min), temperature (5-25°C), and UV-intensities (5.1-10.1 mW/cm2), along with heat treatment (HT, 72°C for 20 s), and untreated samples (C) over a storage period of 150 days. At the beginning of storage, the samples exhibited a dry matter content ranging from 2.15% to 2.38%, pH levels ranging from 3.46 to 3.53, and total acidity between 6.35 and 6.51 mg/L. L* values were recorded between 33.09 and 33.50, while ΔC values ranged from 9.13 to 9.24. However, by the end of storage, these values had changed to 2.28-2.43% for dry matter, 3.47-3.49 for pH, 6.22-6.35 mg/L for acidity, 34.94-35.57 for L* values, and 6.95-7.01 for ΔC values. Throughout storage, total mesophilic aerobic bacteria (TMAB), lactic acid bacteria (LAB), and yeast and molds were measured at the highest levels in the C samples when compared to HT and UV-treated samples. At the end of storage, compared to the initial values, TMAB levels in UV-treated samples decreased from 3.29-4.80 log cfu/mL to 3.13-3.92 log cfu/mL. On the other hand, compared to the initial values (3.29-4.01 log cfu/mL), LAB levels decreased by 1.93-2.42 log cfu/mL by the end of storage. Initially, in UV-treated samples, the TPC (total phenolic content) ranged from 398.15 to 403.86 mg GAE/g, DPPH antioxidant activity ranged from 811.52 to 834.89 mg TE/L, and TAC (total anthocyanin content) ranged from 5.58 to 5.74 mg/L. By the end of storage, an increase was observed in all bioactive properties analyzed. Furthermore, UV treatment positively impacted the bioaccessibility of bioactive compounds compared to the HT-treated sample. Overall, this study confirms that UV-C technology can be used as an alternative method for extending the shelf life of shalgam juice while preserving its sensory and bioactive attributes.

An investigation into the use of incoherent UV light to augment IR nanosecond pulsed laser texturing of CFRP composites for improved adhesion

The preparation of Carbon Fibre Reinforced Polymers (CFRP) surfaces for adhesive bonding has been widely reported. Such reports include laser texturing using both near-infrared (IR) lasers and ultraviolet (UV) lasers. In this report, we present, for the first time, findings showing that surface treatment of CFRP using incoherent UV light, at 254 nm wavelength, can increase the adhesive bonding strength of CFRP by 75 % compared to non-treated samples. It is also around 10 % stronger than NIR laser-textured samples. However, combination treatments, where the UV irradiation is conducted either before or after laser texturing did not give a significant benefit over the laser-textured samples. A germicidal 46 W 254 nm UV lamp was used for the UV light treatment, while an IR nanosecond pulsed fibre laser operating at 1064 nm was used for the laser texturing treatment. The material tested was an autoclave-cured T700 CFRP composite.The wettability of the treated CFRP surfaces and the adhesive bonding were quantitatively assessed. This study concludes that low-cost incoherent UV treatment effectively reduces the water contact angle of the CFRP surface and activates CFRP surfaces. All treatments led to bonding strengths at least 50% greater than for the untreated surfaces.The predominant failure mode for UV-treated samples was Cohesive Substrate Failure (CSF), indicating that the adhesion strength exceeded the interlaminar shear strength of the CFRP material. All samples treated with the laser (including combined treatment with UV) exhibited Light Fibre Tear Failure.

Preventive Effect of Ultraviolet Photofunctionalization on Peri-implant Biofilm Formation: An In vivo Randomized Study.

Peri-implant biofilm formation due to local bacterial colonization is one of the important factors for the instability of temporary anchorage devices (TADs). The aim of this study was to quantify and compare the colonization of Streptococcus sanguinis on ultraviolet (UV) treated and untreated titanium TADs. This prospective, in vivo study included 20 subjects requiring orthodontic treatment with first premolar extraction, followed by retraction of the anterior teeth with absolute anchorage using TADs. TADs were placed interdentally, in the keratinized tissue between the upper second premolar and the first molar on the buccal side, at the mucogingival junction. It was a split-mouth study where one side of TAD was UV-treated for 15 min, and the other side was kept untreated as a control. TADs were removed after 6 months for S. sanguinis quantification on both sides and were compared for biofilm reduction. Statistical software was used to perform unpaired t-tests for the individual samples as well as for comparing total UV-treated and untreated samples. P <0.05 was considered significant. The mean bacterial count (per ml) was found to be 2.2 × 106 copy numbers and 8.9 × 106 copy numbers in the UV group and untreated group, respectively. The total count of bacteria was found to be less in the UV-treated group compared to the untreated group. The study concludes that UV photofunctionalization results in a significant reduction of S. sanguinis colony on TADs with reduced chances of failure due to inflammation.

Added insult to injury? The response of meat-associated pathogens to proposed antimicrobial interventions

Modern requirements for ‘green label’ meat products have led to the design of novel antimicrobial innovations which prioritise quality, safety and longevity. Plasma-functionalised water (PFW), ultraviolet light and natural antimicrobial compositions have been investigated and optimised for control of foodborne pathogens like Campylobacter jejuni and Salmonella enterica serovar Typhimurium. However, given the adaptive mechanisms present in bacteria under external stresses, it is imperative to understand the effect that sublethal treatment may have on the bacterial transcriptome. In this study, Salmonella Typhimurium and C. jejuni were treated with sublethal doses of ultraviolet light, a citrus juice/essential oil marinade, and ‘spark’ or ‘glow’ cold plasma generation system-produced PFW. Immediately after treatment, cells were lysed and RNA was extracted and purified. mRNA was converted to cDNA by reverse transcription-PCR and sequenced by an Illumina MiSeq® system. Sequences were filtered and analysed using the Tuxedo workflow. Sublethal treatment of Campylobacter jejuni and Salmonella Typhimurium led to increased immediate cellular and metabolic activity, as well as diversification in protein and metabolic functioning. There was further expression of pathogenesis and virulence-associated traits associated with spark PFW and marinade treatment of Salmonella Typhimurium. However, similar concerns were not raised with glow PFW or UV-treated samples. This study provides science-based evidence of the efficacy of multi-hurdle antimicrobial system using green-label marinades and PFW or UV to inactivate pathogens without upregulating virulence traits in surviving cells. This study will inform policymakers and food industry stakeholders and reinforces the need to incorporate in-line novel technologies to ensure consumer safety.Key points• Salmonella and C. jejuni showed increased cell activity in immediate response to stress.• Virulence genes showed increased expression when treated with natural antimicrobials and sPFW.• Reduced immediate transcriptomic response to gPFW and UV treatment indicates lower risk.

Impact of 280 nm UV-C LEDs on the microbial safety and nutritional quality in tender coconut water

The efficiency and efficacy of 280 nm UV-C LEDs for processing Tender coconut water (TCW) have been investigated. TCW inoculated with E. coli, and L. monocytogenes were irradiated using collimated beam apparatus at a dose of 71 mJ/cm2 and 20.3 mJ/cm2 for ≥ 5 log CFU/mL reduction, resulting in the double Weibull model for E. coli with a 4D value of 61 ± 0.83 mJ/cm2 and the Weibull model with a 4D value of 13 ± 0.2 mJ/cm2 for L. monocytogenes. The irradiated samples were exposed to photoreactivation (365 nm) light for up to 120 min. PR (Photoreactivation) was eventually not observed for E. coli, and L. monocytogenes showed no repair. Scanning Electron Microscope results revealed that, unlike the control sample, 280 nm irradiation results in cell lysis, wrinkle, and distortion. UV treatment did not affect the pH, TA, Brix, total phenolics content, mineral content, and sugars of TCW but increased in a* and b* colour value, and ascorbic acid concentration reduced to 18.2% of its original concentration. Sensory evaluation studies reported that control samples scored high for freshness and pleasantness, and attributes like astringency, fermented and cooked aroma have been scored low. Overall, the quality of UV-treated samples has been preferred by panellists.

Ultra-Violet-Assisted Scalable Method to Fabricate Oxygen-Vacancy-Rich Titanium-Dioxide Semiconductor Film for Water Decontamination under Natural Sunlight Irradiation

This work reports the fabrication of titanium dioxide (TiO2) nanoparticle (NPs) films using a scalable drop-casting method followed by ultra-violet (UV) irradiation for creating defective oxygen vacancies on the surface of a fabricated TiO2 semiconductor film using an UV lamp with a wavelength oof 255 nm for 3 h. The success of the use of the proposed scalable strategy to fabricate oxygen-vacancy-rich TiO2 films was assessed through UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The Ti 2p XPS spectra acquired from the UV-treated sample showed the presence of additional Ti3+ ions compared with the untreated sample, which contained only Ti4+ ions. The band gap of the untreated TiO2 film was reduced from 3.2 to 2.95 eV after UV exposure due to the created oxygen vacancies, as evident from the presence of Ti3+ ions. Radiation exposure has no significant influence on sample morphology and peak pattern, as revealed by the SEM and XRD analyses, respectively. Furthermore, the photocatalytic activity of the fabricated TiO2 films for methylene-blue-dye removal was found to be 99% for the UV-treated TiO2 films and compared with untreated TiO2 film, which demonstrated only 77% at the same operating conditions under natural-sunlight irradiation. The proposed UV-radiation method of oxygen vacancy has the potential to promote the wider application of photo-catalytic TiO2 semiconductor films under visible-light irradiation for solving many environmental and energy-crisis challenges for many industrial and technological applications.

Adsorption and Inactivation of SARS-CoV-2 on the Surface of Anatase TiO2(101)

We investigated the adsorption of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), the virus responsible for the current pandemic, on the surface of the model catalyst TiO2(101) using atomic force microscopy, transmission electron microscopy, fluorescence microscopy, and X-ray photoelectron spectroscopy, accompanied by density functional theory calculations. Three different methods were employed to inactivate the virus after it was loaded on the surface of TiO2(101): (i) ethanol, (ii) thermal, and (iii) UV treatments. Microscopic studies demonstrate that the denatured spike proteins and other proteins in the virus structure readsorb on the surface of TiO2 under thermal and UV treatments. The interaction of the virus with the surface of TiO2 was different for the thermally and UV treated samples compared to the sample inactivated via ethanol treatment. AFM and TEM results on the UV-treated sample suggested that the adsorbed viral particles undergo damage and photocatalytic oxidation at the surface of TiO2(101) which can affect the structural proteins of SARS-CoV-2 and denature the spike proteins in 30 min. The role of Pd nanoparticles (NPs) was investigated in the interaction between SARS-CoV-2 and TiO2(101). The presence of Pd NPs enhanced the adsorption of the virus due to the possible interaction of the spike protein with the NPs. This study is the first investigation of the interaction of SARS-CoV-2 with the surface of single crystalline TiO2(101) as a potential candidate for virus deactivation applications. Clarification of the interaction of the virus with the surface of semiconductor oxides will aid in obtaining a deeper understanding of the chemical processes involved in photoinactivation of microorganisms, which is important for the design of effective photocatalysts for air purification and self-cleaning materials.

Liposomal Bilayer as a Carrier of Rosa canina L. Seed Oil: Physicochemical Characterization, Stability, and Biological Potential.

Rosa canina L. seeds are rich in bioactive components that can add value to the various formulations. The focus of the study was the development of liposomes for R. canina oil to protect its sensitive compounds and prolong their shelf-life. Oil-loaded liposomes were characterized via the determination of the particle size, polydispersity index (PDI), zeta potential, conductivity, mobility, density, surface tension, viscosity, and stability. Raman and FT-IR spectroscopy were employed to investigate the chemical composition of the non-treated and UV-treated samples, and the presence of different interactions. Antioxidant and antimicrobial activities were examined as well. The liposome size was 970.4 ± 37.4 nm, the PDI 0.438 ± 0.038, the zeta potential -32.9 ± 0.8 mV, the conductivity 0.068 ± 0.002 mS/cm, the mobility -2.58 ± 0.06 µmcm/Vs, the density 0.974 ± 0.004 g/cm3, the surface tension 17.2 ± 1.4 mN/m, and the viscosity 13.5 ± 0.2 mPa•s. The Raman and FT-IR spectra showed the presence of lipids, fatty acids, polyphenols, and carotenoids. It was approved that the oil compounds were distributed inside the phospholipid bilayer and were combined with the membrane interface of the bilayer. The UV irradiation did not cause any chemical changes. However, neither the pure oil nor the oil-loaded liposomes showed any antimicrobial potential, while the antioxidant capacity of the oil-loaded liposomes was significantly low. The sizes of the liposomes did not change significantly during 60 days of storage. Due to the proven stability of the oil-loaded liposomes, as well as the liposome's ability to protect the sensitive oil compounds, their potential application in the pharmaceutical and cosmetic formulations could be investigated with a focus on the skin regeneration effects.

Bulk Polymerization of PEGDA in Spruce Wood Using a DBD Plasma-Initiated Process to Improve the Flexural Strength of the Wood–Polymer Composite

The chemical treatment of wood has been shown to increase its mechanical strength by forming composites with a variety of polymers. Polyethylene glycol diacrylate (PEGDA) has commonly been used as a polymer reinforcement to increase the strength and resistance of spruce wood for various applications, such as protection from weathering. In this study, PEGDA was impregnated into wood samples and polymerized by dielectric barrier discharge (DBD) plasma to form wood–polymer composites (WPCs). The kinetic rate order of PEGDA was explored using FT-IR quantitative analysis and the DBD plasma-initiated polymerization was determined to be second order. The strength of the wood samples was then determined by a three-point flexural test. The PEGDA-treated spruce wood samples showed improved flexural strength versus the untreated wood samples. The WPCs were also made using a UV treatment method and were then compared to the DBD plasma-treated samples. The results showed that the DBD plasma-treated samples yielded superior flexural strength relative to the UV-treated samples. We accredited this difference in strength to the plasma process and its ability to penetrate into the various layers of the wood and initiate polymerization, as opposed to UV light that can only penetrate superficially, initiating polymerization in only the first few layers of the wood surface.

XPS and FTIR investigations of the transient photocatalytic decomposition of surface carbon contaminants from anatase TiO2 in UHV starved water/oxygen environments

This paper explores the transient photocatalytic oxidation mechanism of carbon contaminants from a high surface area anatase TiO2 pellet under starved water/oxygen reaction conditions created when specimens are irradiated via a 375 nm UV laser inside the UHV analysis chamber of an XPS spectrometer. Complementary results are also provided following similar UV irradiations and reaction procedures in an evacuated in situ reaction cell of a Fourier-transform infrared spectrometer (FTIR). An interactive and non-steady state transient photocatalytic reaction is observed between surface carbon species and strongly adsorbed H2O brought to the exterior surface of the pellet via UV photodesorption from within the deeper lying pores of the pellet. The reaction stoichiometry and quantum efficiency of the reaction are reported at various irradiation intensities. In situ FTIR spectral features are also presented and discussed for a non-UV treated TiO2 sample and a 2-hour UV-treated TiO2 sample under evacuated conditions also showing the decomposition of carbon contaminants species and the consumption of adsorbed water/hydroxyls with the ensuing formation of carboxyl (HO-CO) carbon species and isolated surface hydroxyls. The photocatalytic decomposition of carbon species and the concomitant consumption of oxygen containing species was also tracked by following the XPS spectral changes of a UV-irradiated area on the pellet surface compared to a dark reference spot on the same specimen. Eight different reaction cases at four different UV intensities, repeated twice each, were also investigated using separate pieces of the same TiO2 media. The measured stoichiometry for the decomposition of carbon species and consumption of oxygen ranged from 0.53 during the first 10–20 min of irradiation and increased to 0.65 with an average value of 0.59 and a standard deviation of 0.11. These data suggest that the reaction product and leaving group from the TiO2 surface is primarily CO2 during the first 10–20 min of initial reaction with perhaps a small fraction of CO toward the end of reaction. Heating the sample specimen to 100 °C for 2-hour inside the XPS-UHV analysis chamber prior to UV illumination was effective in eliminating photocatalytic oxidation and carbon removal from the surface thereby demonstrating that strongly adsorbed water (prior to heating in vacuum) was a critical and limiting reagent in the overall H2O transport and reaction process.Photon efficiencies for the reaction were calculated based on the number of carbon species removed from the XPS-observable surface versus the number of the UV photons adsorbed in the topmost 2 nm of the sample. The highest photon efficiency observed was 0.0186 after 5–10 min of UV exposure at 1.5 mW/cm2. All reaction cases showed a significant efficiency drop after 30 min of UV irradiation due to the consumption of the adsorbed reactants, both carbon and water. From detailed deconvolution of the XPS C 1s spectra, UV irradiation showed a high selectivity towards hydrocarbon contaminant decomposition, which was 75% ± 5% of all carbon species removed.

Association Between Thalassemia and Leucocytic DNA Damage: A Pilot Study

Objectives: Thalassemia with frequent blood transfusion was considered under oxidative stress because of the chance of iron overload. Patients with thalassemia trait with no blood transfusion might also suffered from oxidative stress because of increased iron metabolism. This pilot study was to investigate if patients of alpha or beta thalassemia trait and received no blood transfusion were suffered from oxidative stress in term of DNA damage in peripheral leucocytes. Method: Comet assay was used to measure DNA damage of 20 normal subjects, 8 alpha and 12 beta thalassemia patients who did not received blood transfusion. The baseline and UV-mediated DNA damages of peripheral white blood cells were measured. The degree of DNA damage was quantified by visual scoring under light microscope after staining with Giemsa stain. Results: The mean (± standard deviation) comet score for normal baseline samples was 8.3 ± 6.1 whereas 105.4 ± 15.7 and 69.8 ± 20.3 for alpha and beta thalassemia respectively. While the comet scores were 71.9 ± 19.6, 193.1 ± 21.8 and 211.8 ± 51.6 for normal, alpha and beta thalassemia samples respectively in UV-treated samples. Results showed that both alpha and beta thalassemia patients had higher leucocytic DNA damage in baseline and oxidative stressed samples. Conclusion: Our data suggested thalassemia patients were under oxidative stress even no iron over loaded through transfusion.

Impact of the surface modifications and cell culture techniques on the biomechanical properties of PDMS in relation to cell growth behavior

PDMS is the most widely used material in the microfluidic systems because of its advantageous properties including ease of manufacture, low cost, transparency, and gas permeability. Although all biomaterials need to be sterilized for usage for in vitro or in vivo systems to avoid possible contaminants, none of them proved effective in providing the gold standards so far for PDMS sterilization. Therefore we evaluated the influence of both UV and ethanol sterilization of PDMS substrates on the cell behavior via investigating cell proliferation, oxidative stress and nutrient metabolism of 293 T cells growing on the PDMS first time in the literature. Modulus of elasticity and stress relaxation of UV-treated PDMS samples increased compared to the ethanol-treated ones leading to a state of surface stiffness preferable for cell growth and proliferation. Oxidative stress metabolism of cells growing on the UV-treated PDMS was more stable compared to the ethanol-treated samples. Trace element and mineral metabolism are not impaired in the cells growing on the UV-treated PDMS samples. First time in the literature, we showed that UV treatment is more suitable for the PDMS samples used in the cell culture experiments.

Carbapenem-resistant bacteria over a wastewater treatment process: Carbapenem-resistant Enterobacteriaceae in untreated wastewater and intrinsically-resistant bacteria in final effluent

Although urban wastewater treatment plants (UWWTPs) are important sites for antibiotic resistance elimination, their limitation in producing resistance-free effluents is recognized. Despite the critical importance of carbapenems to human health, the fate and diversity of carbapenem-resistant bacteria (CRB) in UWWTPs is still poorly understood. We analysed CRB from different treatment stages in a UWWTP applying UV-C radiation. After secondary treatment, bacteria grown in mFC medium reduced in 1.9-log units (p < 0.0001), while CRB counts reduction (0.2-log units) was not significant. UV-C reduced the abundance of total bacteria and CRB (1.8 and 2.4-log units, respectively, relative to values after secondary treatment). Yet after incubation in the dark, CRB increased (0.6-log units) in UV-treated samples. Albeit in low amounts, carbapenem-resistant Enterobacteriaceae (CRE) were detected in raw wastewater being absent from the final effluent. Thirty-four CRE isolates were identified as Citrobacter, Enterobacter, Leclercia and Lelliottia. These were multiresistant and yielded classes 1, 2 and 3 integrons (94%, 88% and 88%, respectively). In all CRE isolates, blaGES-5 was found in integrons. Three isolates were selected for whole-genome sequencing; in Citrobacter braaki (n = 2) blaGES-5 was part of class 3 integrons, while in Lelliotia sp. RWM.1 blaGES-5 was in a class 1 integron with a novel cassette array (blaOXA-10/aacA4-blaGES-5-blaBEl-1). These integrons were in contigs with high similarity with mobilizable plasmids. Genes encoding resistance to other antibiotics were detected in these isolates. In the final effluent, CRB were predominantly affiliated with Stenotrophomonas maltophilia.UV-C radiation significantly reduced the abundance and prevalence of CRB. Bacteria intrinsically-resistant to carbapenems were cultivated after all treatment stages, while CRE only in raw wastewater. In these samples, we detected CRE with blaGES-5, in integrons and plasmids. This raises concern as horizontal gene transfer may occur within these systems. Carbapenem resistance surveillance in UWWTPs is essential to implement mitigation measures in a timely manner.

Comparison of UV, Peracetic Acid and Sodium Hypochlorite Treatment in the Disinfection of Urban Wastewater.

One source of water contamination is the release of wastewater that has not undergone efficient treatment. The aim of this study was to evaluate the reduction obtained with sodium hypochlorite (NaClO), UV and peracetic acid disinfection treatment of Salmonella spp., pathogenic Campylobacter, STEC and bacterial indicators in three full-scale municipal wastewater plants. A general reduction in Salmonella was observed after disinfection, but these bacteria were detected in one UV-treated sample (culture method) and in 33%, 50% and 17% of samples collected after NaClO, UV and PAA disinfection treatments, respectively (PCR method). A better reduction was also observed under NaClO disinfection for the microbial indicators. Independent of the disinfection treatment, E. coli O157:H7 was not detected in the disinfected samples, whereas some samples treated with UV and PAA showed the presence of the stx1 gene. No reduction in the presence of stx2 genes was verified for any of the disinfection treatments. Campylobacter was not detected in any of the analysed samples. The overall results highlight a better reduction in microbiological parameters with a NaClO disinfection treatment in a full-scale municipal wastewater plant compared with UV and PAA. However, the results indicate that a complete and specific monitoring program is necessary to prevent a possible risk to public health.

ATR-FTIR Analysis of Orthodontic Invisalign® Aligners Subjected to Various In Vitro Aging Treatments.

Clear and removable tooth aligners for orthodontics treatments have become an increasingly popular alternative to fixed appliances. Even if protocols suggest removing aligners before eating or drinking, most patients retain them when they drink beverages. Alterations in the material during the daily use could determine a reduction in the application forces, affecting the desired orthodontic movement; the knowledge of how this material reacts when subjected to different aging processes is mandatory to establish the predictability of the orthodontic treatment. According to this, the aim of the present study was to assess a new objective approach, coupling spectroscopic and chemometric tools, to evaluate the changes occurring in Invisalign® aligners, the most widely used brand, exposed in vitro to coffee, tea, Coca Cola® and UV radiation for 24 and 48 h. In particular, ATR-FTIR spectroscopy was utilized to characterize, at the molecular level, the chemical and color modifications in the surfaces of the appliances; the obtained data were submitted to PCA and one-way ANOVA and Tukey’s multiple comparison test. Moreover, a colorimetry analysis was carried out to evaluate any changes in color and transparency. Coffee and tea samples displayed the major color changes between the tested groups. The differences highlighted in the spectral features of coffee, tea and UV-treated samples were mainly ascribable to color and transparency changes, because the chemical properties remained unaltered.

UV Pretreatment Impairs the Enzymatic Degradation of Polyethylene Terephthalate.

The biocatalytic degradation of polyethylene terephthalate (PET) emerged recently as a promising alternative plastic recycling method. However, limited activity of previously known enzymes against post-consumer PET materials still prevents the application on an industrial scale. In this study, the influence of ultraviolet (UV) irradiation as a potential pretreatment method for the enzymatic degradation of PET was investigated. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and 1H solution nuclear magnetic resonance (NMR) analysis indicated a shortening of the polymer chains of UV-treated PET due to intra-chain scissions. The degradation of UV-treated PET films by a polyester hydrolase resulted in significantly lower weight losses compared to the untreated sample. We also examined site-specific and segmental chain dynamics over a time scale of sub-microseconds to seconds using centerband-only detection of exchange, rotating-frame spin-lattice relaxation (T1ρ), and dipolar chemical shift correlation experiments which revealed an overall increase in the chain rigidity of the UV-treated sample. The observed dynamic changes are most likely associated with the increased crystallinity of the surface, where a decreased accessibility for the enzyme-catalyzed hydrolysis was found. Moreover, our NMR study provided further knowledge on how polymer chain conformation and dynamics of PET can mechanistically influence the enzymatic degradation.

Application of Ultraviolet Radiation to Control the Calcium Carbonate Scale Formation and Deposition on the Membranes

Scale formation on surfaces in contact with water supersaturated with calcium carbonate creates technical problems, including heat transfer hindrance, energy consumption, and equipment shutdown. Thus, nowadays, there is an increasing need for new approaches that are environmentally friendly and economically feasible. In this work, for the first time, calcium carbonate growth was investigated using UV light exposure, and the growth rate was compared with control and commercial antiscalant. Saturated calcium carbonate samples were exposed to UV radiation; the growth rate of calcium carbonate crystals was monitored at different time intervals. Results clearly show that about 85% decrease in crystal growth rate was observed when compared to 43% after the addition of 3 mg/L of amino tris(methylene phosphonic acid) antiscalant. Calcium carbonate scale deposition on hydrophobic and hydrophilic membranes was investigated. The amount of scale deposited in the case of a UV-treated sample is insignificant when compared to control samples. Thus, the exposure of UV might help to improve the membranes’ lifetime. X-ray diffraction and scanning electron microscopy analyses revealed that UV light treatment produced mostly calcite crystals. The produced calcites are less dense and less adherent, and it can be easily removable when compared to other types of calcium carbonate phases. Thus, UV radiation is an efficient green approach for calcium carbonate scale mitigation on membrane surfaces.

Review of surface treatment methods for polyamide films for potential application as smart packaging materials: surface structure, antimicrobial and spectral properties

Abstract Background Antimicrobial packaging is currently one of the emerging technologies being pursued to extend the shelf-life of food products. Polyamides (PA) are widely used in food packaging, principally in laminate constructions, where they are used alone or combined with other materials. PA can be surface-treated using UV, plasma and corona treatments to create active film surfaces for various industrial applications. Scope and Approach the object of this article was to review different surface treatment methods for the potential manufacture of smart packaging materials including antimicrobial application in particular and to review the necessary spectral characteristics deemed necessary to achieve this. Key Findings and Conclusions XPS and AFM methods are useful tools in the identification of film surface analysis. For UV treatment, different light sources, including lasers, can be applied to create antimicrobially-active packaging materials. UV-treated PA films possess antimicrobial properties and offer potential for industrial and medical packaging applications, however, the application of such packaging materials to foods needs some special consideration. Different plasma treatment methodologies can be used for modification of PA surfaces, followed by attachment of antimicrobial coatings which are very limited in literature. Surface studies have shown that plasma-treated PA surfaces possess spectral properties similar to those for UV-treated samples. Corona treatment, like UV and plasma treatments, induce the modification of functional groups on PA film surfaces. Corona treatment has the capacity to activate polymeric surfaces for adhesion of a variety of functional coatings and should be explored further in terms of creating special antimicrobial coatings.

Effect of 172-nm UV irradiation on polyimide and its application in surface modification by grafting

Polyimides (PIs) have a wide range of industrial and scientific applications due to their excellent thermal and mechanical stability and chemical resistance. Their response to ultraviolet (UV) irradiation is of further interest in high-value applications such as spacecraft technology and electronics packaging. In this work, we investigated the effect of 172-nm UV xenon excimer lamp irradiation on samples of pyromellitimido-oxydianiline (PMDA-ODA) commercial films in the absence of oxygen. The average irradiance received at the sample position was 90 mW/cm2, and the total radiation dosage varied from 0 to 64 J/cm2. X-Ray photoelectron spectroscopy, time-of-flight-secondary ion mass spectrometry, atomic force microscopy, and contact angle measurements were used to characterize the effect. Calculated UV-visible spectroscopy absorption spectra were obtained using the ZINDO//B3LYP/3-21G method to give an indication of which orbitals are involved in the transitions near 172 nm. The reactivity of the different UV-treated PI samples toward nitrogen-borne heptafluorodecene vapor was then investigated using the above techniques. Grafting reactions occurred on the surface of the photochemically activated polymer. This study explored the potential for modification of PI surfaces using UV-light-assisted grafting to impart valuable functionalities.