UV Light Exposure Research Articles

Reusable Microfluidic Chambers for Single-Molecule Microscopy.

Maintaining a consistent environment in single-molecule microfluidic chambers containing surface-bound molecules requires laborious cleaning and surface passivation procedures. Despite such efforts, variations in nonspecific binding and background signals commonly occur across different chambers. Being able to reuse the chambers without degrading the surface promises significant practical and fundamental advantages; however, this necessitates removing the molecules attached to the surface, such as DNA, proteins, lipids, or nanoparticles. Biotin-streptavidin attachment is widely used for such attachments, as biotin can be readily incorporated into these molecules. In this study, we present single-molecule fluorescence experiments that demonstrate effective resetting and recycling of the chambers at least 10 times by using photocleavable biotin (PC-biotin) and UV-light exposure. This method differs from alternatives as it does not utilize any harsh chemical treatment of the surface. We show that all bound molecules (utilizing various PC-biotin attachment chemistries) can be removed from the surface by a 5 min UV exposure of a specific wavelength. Nonoptimal wavelengths and light sources showed varying degrees of effectiveness. Our approach does not result in any detectable degradation of surface quality as assessed by the nonspecific binding of fluorescently labeled DNA and protein samples and the recovery of the DNA secondary structure and protein activity. The speed and efficiency of the resetting process, the cost-effectiveness of the procedure, and the widespread use of biotin-streptavidin attachment make this approach adaptable for a wide range of single-molecule applications.

How long do bacteria, fungi, protozoa, and viruses retain their replication capacity on inanimate surfaces? A systematic review examining environmental resilience versus healthcare-associated infection risk by "fomite-borne risk assessment".

SUMMARYIn healthcare settings, contaminated surfaces play an important role in the transmission of nosocomial pathogens potentially resulting in healthcare-associated infections (HAI). Pathogens can be transmitted directly from frequent hand-touch surfaces close to patients or indirectly by staff and visitors. HAI risk depends on exposure, extent of contamination, infectious dose (ID), virulence, hygiene practices, and patient vulnerability. This review attempts to close a gap in previous reviews on persistence/tenacity by only including articles (n = 171) providing quantitative data on re-cultivable pathogens from fomites for a better translation into clinical settings. We have therefore introduced the new term "replication capacity" (RC). The RC is affected by the degree of contamination, surface material, temperature, relative humidity, protein load, organic soil, UV-light (sunlight) exposure, and pH value. In general, investigations into surface RC are mainly performed in vitro using reference strains with high inocula. In vitro data from studies on 14 Gram-positive, 26 Gram-negative bacteria, 18 fungi, 4 protozoa, and 37 viruses. It should be regarded as a worst-case scenario indicating the upper bounds of risks when using such data for clinical decision-making. Information on RC after surface contamination could be seen as an opportunity to choose the most appropriate infection prevention and control (IPC) strategies. To help with decision-making, pathogens characterized by an increased nosocomial risk for transmission from inanimate surfaces ("fomite-borne") are presented and discussed in this systematic review. Thus, the review offers a theoretical basis to support local risk assessments and IPC recommendations.

Recoverable and reusable light-induced multi-arm azobenzenes-Fe3O4 hybrid sorbent for enrichment of phthalate plasticizer and utilized as a SALDI substrate for the detection of 2-naphthol

The construction, structural identifications along with compositional properties, using TEM, FT-IR, and XPS spectroscopies, of an innovative light-induced multi-arm azobenzenes based Fe3O4 magnetic nanoparticles (Azo-Fe3O4 MNPs) are being reported. Such organic (light-sensitive dendrimers-like structure), inorganic (magnet core), hybrid material has been applied as an efficient recoverable/reusable extractive sorbent for the detection of phthalate plasticizers from acetate buffer solution. The extraction study was controlled within consecutive procedures via UV-light exposure to achieve pore-size control which then further subjected for the evaluation of the analytes’ retention, separation, and release as well as the detection of the phthalate pollutants using GCMS–. Various experimental conditions, such as time of extraction, salt concentration, pH, and desorption time, were studied and adjusted. Additionally, the extraction repeatability (RSD from 0.46 % to 6.12%, n = 5) of the studied sorbent was comparable to other published work. The linear range extended from 6.25 to 100 μg L-¹ and detection limits (LOD) within the range of 41- 150 ng L-1 were achieved, demonstrating good linearity with values ranging from 0.9992 to 0.9892. The inter-batch and intra-batch RSD ranged from 0.46 % to 6.12 %, respectively. Additionally, it provides effective detection of 2-naphthol when used as a SALDI substrate.

Conjugated Polymer-Based Photo-Crosslinker for Efficient Photo-Patterning of Polymer Semiconductors.

Photo-patterning of polymer semiconductors using photo-crosslinkers has shown potential for organic circuit fabrication via solution processing techniques. However, the performance of patterning, including resolution (R), UV light exposure dose, sensitivity (S), and contrast (γ), remains unsatisfactory. In this study, a novel conjugated polymer based photo-crosslinker (PN3, Figure 1a) is reported for the first time, which entails phenyl-substituted azide groups in its side chains. Due to the potential π-π interactions between the conjugated backbone of PN3 and those of polymer semiconductors, PN3 exhibits superior miscibility with polymer semiconductors compared to the commonly used small molecule photo-crosslinker 4Bx (Figure 1a). Consequently, photo-patterning of polymer semiconductors with PN3 demonstrates improved performance with much lower UV light exposure dose, higher S and higher γ compared to 4Bx. By utilizing electron beam lithography, patterned arrays of polymer semiconductors with resolutions down to 500nm and clearer edges are successfully fabricated using PN3. Furthermore, patterned arrays of PDPP4T, the p-type semiconductor (Figure 1b), after being doped, can function as source-drain electrodes for fabricating field-effect transistors (FETs) with comparable charge mobility and significantly lower sub-threshold swing value compared to those with gold electrodes.

Enhanced Flexible Piezoelectric Nanogenerators Using Ethanol-Exfoliated g-C3N4/PVDF Composites via 3D Printing for Self-Powered Applications.

This study presents the development of flexible piezoelectric nanogenerators (PENGs) utilizing graphitic carbon nitride (g-C3N4) nanoflakes (CNNFs) and polyvinylidene fluoride (PVDF) composites fabricated via the direct ink writing (DIW) 3D printing method. A novel approach of synthesizing CNNFs using the ethanol exfoliation method was demonstrated, which significantly reduces preparation time and cost compared to traditional acid exfoliation. The CNNFs are incorporated into PVDFs at varying weight percentages (5, 7.5, 10, and 15 wt.%) to optimize the β-phase content and piezoelectric properties. Characterization techniques including XRD, FTIR, and FESEM confirm the successful synthesis and alignment of nanoflakes inside the PVDF matrix. The film with 7.5% CNNF achieves the highest performance, exhibiting a peak output voltage of approximately 6.5 V under a 45 N force. This study also explores the effects of UV light exposure. Under a UV light, the film exhibits an output voltage of 8 V, indicating the device's durability and potential for practical applications. The fabricated device showed significant voltage outputs during various human motions, confirming its suitability for wearable self-powered IoT applications. This work highlights the efficacy of the ethanol exfoliation method and the DIW printing technique in enhancing the performance of flexible PENGs.

Dual Eu3+ and Er3+ doping in ZnO nanoporous 2D frameworks for tuning photocatalytic activity, linear and non-linear optical response

Recent days, the greater attention of research materials are focusing on the porous nano frame structure due to their distinctive properties and high photocatalytic activity. The porous defective materials revealed a significant role in numerous research fields like sensors, catalysts, energy production, magnetic memory storage, bio medical etc. In our work, pure ZnO and 4f shell shielded rare earth metals doped ZnO metal oxide nanomaterials attributed in the photocatalytic dye degradation, non-linear optical and magnetic properties. We were synthesized pure ZnO and ZnO0.1–2xEuxErxHMT0.1–2x (2x = 0.025,0.05,0.075, 0.010 wt%) nanoparticles using a straightforward hydrothermal route. The hexagonal wurtzite structure of ZnO and Eu:Er-doped ZnO (Eu:Er@ZnO) exhibited by PXRD, and the optical bandgap (Eg) range from 3.14 eV to 3.18 eV was determined by Tauc relation (αhγ)2 = 0. The porous nanoplate morphology of as-synthesized materials revealed by HR-SEM and HR-TEM techniques. All synthesized materials exposed weak ferromagnetic property nature by VSM studies. Among all the synthesized materials, the 0.0025 wt% Eu:Er@ZnO nanoparticles exhibited porous nanoplate structures capable of catalyzing the breakdown of reactive black 5 (RB5) dye, achieving a photocatalytic activity of 93.2 % after 65 min of UV light exposure. The dopant concentration significantly influenced this photocatalytic activity, with lower concentrations showing enhanced performance, particularly in acidic conditions. Moreover, all synthesized porous nano-plate materials followed pseudo-first-order kinetics. Additionally, the Z-scan technique was employed to assess the nonlinear optical properties of the synthesized materials using Q-switched nanosecond Nd laser pulses at 532 nm wavelength. The open-aperture Z-scan revealed reverse saturable absorption (RSA) in all samples. The Eu:Er@ZnO porous nano-plates exhibited promising nonlinear absorption characteristics, with a higher nonlinear absorption coefficient ranging from 5.21 to 7.84 × 10−11 m/W and a lower optical limiting threshold between 0.87 and 0.95 × 1012 W/m2.

Degradation of Microplastics by Zinc Oxide Nanoparticles Synthesized Using Piper longum Leaf Extract.

Background: The environmental hazards posed by microplastics have drawn considerable concern due to their buildup in ecosystems. Microplastics accumulate in human saliva, skin, and hair. Developing effective technology for managing and degrading microplastics remains a substantial challenge. In a concerted attempt to save the ecology, this study explores the photocatalytic breakdown of common microplastics like polystyrene (PS) microspheres and polyethylene (PE) using green-synthesized zinc oxide nanoparticles (ZnO NPs) under UV light exposure. Aim: To synthesize and characterize zinc oxide nanoparticles prepared using the extract of the leaves of Piper longumand qualitatively assess the photocatalytic degradation potential of the nanoparticles under light microscopy. Material and Methods:A fresh extract of P. longum leaves was used as a reducing agent to synthesize zinc oxide nanoparticles. Fourier transform infrared (FTIR) analysis, X-ray diffraction (XRD) analysis, UV-Vis spectra analysis, and scanning electron microscopy (SEM) analysis were performed to characterize the nanoparticles. Microplastics were isolated from the saliva of 50 healthy patients and were purified and filtered. In a six-well microtiter plate, 0.5 μg of varying concentrations of nanoparticles were added. After fixing with 15% formaldehyde, microplasticswere subjected to UV irradiation for 2 hours with different concentrations of ZnO nanoparticles (25, 50, 75,and 100 µg). Custom photoreactors activated the photocatalysts to degrade the microplastic pollutants. The six-well microtiter plate was viewed under 40x magnification in a light microscope to observe microplastic morphology after 24 hours of degradation. Results: The FTIR spectrum showed distinct peaks at 890.51 cm⁻¹, indicating the involvement of C-N in-plane vibrations of amino acids. XRD analysis revealed three distinct diffraction peaks at 31.68°, 34.39°, and 36.33°, corresponding to the hexagonal wurtzite structure of ZnO nanoparticles. The synthesized ZnO nanoparticles ranged from 50 to 90 nm in size, viewed at 100x magnification on SEM. The highest degradation of microplastics was observed ataZnO NPconcentration of 100 µL, with the ZnO NPs 50-90 nm in size. Conclusion: Zinc oxide nanoparticles synthesized using Piper longum leaf extract effectively degrade microplastics, with the highest degradation observed at a 100 µL concentration of ZnO nanoparticles and optimal degradation occurring at a concentration of 75 µL.

Contamination patterns of the neonatal equipment, major microorganisms, and effectiveness of disinfection procedures including refurbished UV C lights at the University Teaching Hospital of Butare (CHUB)

A contaminated environment plays a significant role in transmitting hospital-acquired infections (HAIs) but regular chemical disinfection is the backbone for tackling this chain of transmission and the combination of both UV lights may increase the effectiveness of cleaning. This study assessed the effectiveness of chemical disinfection, with and without additional UV light exposure, in reducing bacterial contamination in a Neonatal unit. Therefore, interventions consisted of usual chemical disinfection with and without a 2-hour exposure to Ultraviolet light from refurbished UV lamps. Researchers swabbed high-touch surfaces and equipment before and after disinfection to identify bacterial presence. They found that 36.4% of the sampled sites showed bacterial growth, with the nursing trolley being the most contaminated. The most common bacteria isolated was Klebsiella pneumoniae (50%), which, along with other bacteria, displayed high resistance to commonly used antibiotics like Amoxicillin + Clavulanic acid and Cefuroxime. Only Meropenem and Amikacin remained effective. The study concludes that despite chemical disinfection, bacterial contamination remains significant, and conventional UV light alone did not completely eradicate bacteria, highlighting the need for more effective disinfection strategies. Keywords: Neonatology Service, University Teaching Hospital of Butare (CHUB), hospital-acquired infections (HAIs), disinfection

Nanostructured hexagonal S-doped CeO2 for effective Rh-B and MB dye degradation

The photocatalytic efficiency of CeO2−xSx (x = 0.05, 0.1, 0.2, 0.3, 0.5) hexagonal nanoparticles (HNPs) prepared through the hydrothermal method were tested by performing the degradation of Rhodamine-B and Methylene blue dyes under UV light irradiation. These compounds were thoroughly characterised using XRD, FESEM, EDX, HRTEM, XPS, ESR, FTIR, Raman, UV–vis DRS, BET and PL techniques. XRD analysis verified the cubic crystal structure of S-doped and pure CeO2 HNPs. HRTEM images clearly affirmed that S-doped CeO2 is made from HNPs. Over 94 % of Rh-B and 72 % of MB dyes were degraded by S-doped CeO2 for 180 min under UV light exposure, demonstrating its efficacy towards the photocatalytic activity (PCA). S-doped CeO2 HNPs have enhanced the PCA due to the reduction in the recombination rate of photo-generated electron-hole pairs, the rise in oxygen vacancy (Ov) and the narrowed optical band-gap. The photoluminescence findings clearly validated the increased PCA of S-doped CeO2. The scavenger tests confirmed the OH• and •O2− radicals participation in the quick degradation of both Rh-B and MB dyes.

Reversible Switching of Light‐Gated Organic Transistors Employing Dihydroazulene/Vinylheptafulvene Photo‐/Thermochromic Molecules

AbstractAn innovative possibility to introduce additional functionality to organic field‐effect transistors (OFETs) is to employ photochromic molecules, which undergo reversible isomerization under applied stimuli such as irradiation with specific wavelengths. As a result, the transistors not only can be switched on/off by the applied voltages, they can also be programmed by alternate triggers, such as light. Here, reversible switching of OFETs is presented by blending various dihydroazulene/vinylheptafulvene photoswitches into polythiophene‐based conjugated polymers. In result, the transfer characteristics of the transistors are altered significantly through UV irradiation. In contrast to current literature on different photoswitches such as spiropyrans or diarylethenes, the backreaction is induced thermally and not via visible light irradiation and reproducibly yields the pristine transistor characteristics. This reversible switching upon alternating UV irradiation and thermal annealing is quantified by figures of merit such as the magnitude of drain current, threshold voltage, and subthreshold swing. Irradiating the devices with different doses of UV light shows that the magnitude of switching directly depends on the respective UV dose, hence enabling a multi‐level electronic system. Furthermore, long‐term cyclability over 100 steps of repeated UV light exposure and thermal annealing is demonstrated.

Highly enhanced photocatalytic hydrogen production via GO-modified Cu-TiO2 system for dehydrogenation of alcohols under UV & sunlight irradiation

The high efficiency of the production of hydrogen from alcohols is vital to the advancement of energy technology. This study thoroughly investigates the process of alcohol dehydrogenation utilising GO-modified Cu-TiO2 photocatalyst under UV light and sunlight exposure. GO-modified Cu-TiO2 photocatalyst was synthesised using the hydrothermal method. Various experimental techniques, including FESEM, HRTEM, XPS, and DRS, confirmed the formation of the ternary composite. The influence of different alcohols (methanol, ethanol, propanol) and their concentrations (same vol% and molarity) on the amount of hydrogen (H2) production was examined in this study. The study thoroughly investigated the impact of various parameters, such as the influence of GO and Cu loading on TiO2 and their combined effect, time course, nature of alcohol and the reaction conditions on the photocatalytic hydrogen production. The GO(0.5 wt%)/Cu(3 wt%)-TiO2 (G0.5C3T) composite demonstrated the highest quantity of hydrogen production during methanol dehydrogenation when subjected to both UV and sunlight irradiation. The composite exhibited remarkably about three-fold higher hydrogen evolution in sunlight(881 mmol) than in UV light(294 mmol). The exceptional performance of this composite can be attributed to the efficient transfer of charge carriers and the delayed recombination of electron-holes, which is a result of the cooperative effect of GO and Cu deposited over the TiO2 system. This approach offers a proactive strategy, signifying the synergetic effect of loading GO and Cu over TiO2 to enhance the photocatalytic hydrogen production, which is regarded as a green fuel solution, and turns these materials into useful energy sources by using inexpensively synthesised photocatalysts.

Using the potential of Canadian goldenrod (Solidago canadensis) as a functional filler with antioxidant activity of low-density polyethylene composites as an example of sustainable development of an invasive plant

Novel bio-based low-density polyethylene (LDPE) composites have been manufactured using different Canadian goldenrod (CG) invasive plant parts. Fragmented and ground blossoms (CGB) and mixed leaves and stems (CGSL) were used as fillers introduced by melt mixing into an LDPE matrix at various concentrations (2, 5, 10, 20, 40 wt%). Moreover, the influence of a series of modified fillers based on stems and leaves saturated with an extract made of blossoms (CGSL+E) on LDPE has been verified. The oxidation resistance of composites was enhanced based on the oxidation induction time (OIT) assessment, which increased from 0.5 min for LDPE to 178 min (CGB), 231 min (CGSL), and 140 min (CGSL+E). All composite series formed by compression molding were exposed to UV-light radiation using Xenon lamps and subjected to spectroscopic (FTIR) analysis, color assessment, and mechanical testing. LDPE/CGSL+E composites demonstrated the most favorable mechanical properties after UV-light exposure. In their case, an increase in Young modulus of 360 MPa was observed for the 40 wt% sample (PE ∼ 180 MPa) and an acceptable decrease in tensile strength of 6.5 MPa compared to the reference LDPE of 9.8 MPa. The study consists of a screening for future research on the use and simultaneous valorization of the invasive plant into functional composite fillers with increased oxidation resistance.

Sericin-TiO2 nanocomposite treated cotton fabrics for enhanced antibacterial and self-cleaning properties

The valorization of industrial byproducts is rising as a new dawn and has become a creative area of research for the scientists. Sericin is being a good resource of starting materials since it can be recovered and recycled. The research aimed to modify cotton fabric by sericin-TiO2 nanocomposite (STNc) for enhancement its antibacterial and self-cleaning properties. STNc were prepared using tetraisopropylorthotitanate (TIOT) and sericin with proportions 2:1, 2:2 and 1:2. The obtained STNc possesses anatase phase of TiO2 nanoparticles having an average 22.9 nm particle sizes. The STNc coated cotton samples were prepared with three different weight fractions of STNc and citric acid (2:1:2, 2:2:1 and 1:2:2). The incorporation of STNc onto cotton fabric was examined by FTIR spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses. The antibacterial activity of STNc coated cotton fabrics was investigated against drug resistant bacterium viz. Staphylococcus aureus, Pseudomonas 4A and Escherichia coli. The STNc coated cotton fabric exhibited effective resistance against Escherichia coli and Staphylococcus aureus. The antibacterial properties of STNc coated cotton fabrics were depended with the fraction of STNc. The uncoated and STNc coated cotton fabrics were stained with coffee and then irradiated on sunlight for 0, 30, 60, 90 h and UV light for 2, 4, 6, 8, 10 h. A noticeable decrease in the coffee stain's appearance was observed after 90 h sunlight and 10 h UV light exposure for STNc coated cotton fabric. The reusability of photo exposed samples was evaluated by FTIR spectroscopy.

Utilization of photocatalytic degradation and efficiency of engineered geopolymer composite tile doped with nano-particles under ultraviolet light

This study investigates the impact of nano-zinc oxide (ZnO) on the self-cleaning and microstructural performance of engineered geopolymer composites (EGC) for urban cleanliness enhancement. The research focuses on achieving homogeneous dispersion of nano-ZnO through ultrasonication to prevent agglomeration and assess its effects on workability, setting time, mechanical, and microstructural properties of EGC. Results show that incorporating ZnO nanoparticles at 5 % and 10 % concentrations as a surface coating on engineered geopolymer composite creates a highly effective photocatalytic material. This enhanced composite demonstrates significant capability in degrading Rhodamine B (RhB) under UV light exposure over a 15-day period, breaking down organic pollutants into simpler, potentially less toxic substances. The efficiency of degradation depends on factors such as nano-ZnO concentration, UV radiation intensity, and initial pollutant concentration. The optimal dosage of nano-ZnO in EGC is found to be 0.5 %, which enhances hydration and pozzolanic activity, promoting a densified microstructure at the nanoscale. This innovative composite material shows promise as a self-cleaning finishing material for urban buildings, offering potential improvements in both aesthetics and environmental sustainability.

Synthesis, structure, and photochromic properties of Zn-coordination polymers derived from hexyl viologen cations

This study presents the synthesis, structural characterization, and investigation of the photochromic properties of two Zn-coordination polymers, formulated as {(HV)0.5[Zn(MIC)(HMIC)]·H2O}n (1) and {(HV)2[Zn4(BTEC)3]}n (2) (H2MIC = 5-methylisophthalic acid, H4BTEC = 1,2,4,5-benzenetetracarboxylic acid, HVBr2 = 1,1′-bis(n-hexyl)-4,4′-bipyridinium dibromide), derived from hexyl viologen cations. Compound 1 is characterized by a one-dimensional (1D) structure, while compound 2 exhibits a three-dimensional (3D) architecture, both crystallizing in distinct space groups and showcasing unique assembly and composition. Detailed structural analysis reveals the coordination modes of Zn(II) ions within these polymers. The photochromic behavior of two compounds under UV light exposure was thoroughly examined through ultraviolet-visible (UV–vis) and electron paramagnetic resonance (EPR) spectroscopy, demonstrating reversible color changes from light yellow to blue upon irradiation, with distinct rates of decolorization indicative of the stability of photo-induced viologen radicals. This reversibility was successfully replicated over multiple cycles, underscoring the durability of the photochromic transition. Furthermore, powder X-ray diffraction (PXRD) data confirmed the maintenance of crystal structures throughout the photochromic process, dismissing photolysis or photo-induced isomerization as underlying mechanisms. Instead, the observed photochromism is attributed to efficient electron transfer facilitated by the proximity between electron-donating and electron-withdrawing groups within the coordination polymers. This study highlights the influence of structural parameters on the photochromic properties of viologen-based coordination polymers, offering insights into the design of photo-responsive materials.

Synthesis of blue-sparkling N, S-doped carbon dots for effective detection of nitro explosive and Fe3+ ion and anti-counterfeiting studies

Highly blue-luminescent nitrogen & sulfur-doped carbon dots (N, S-CDs) made with homocysteine and ethylene diamine by simple single-step microwave-assisted style. The prepared carbon dots showed a higher photoluminescent quantum yield (PL-QY), which is found to be 45 %. FTIR and XPS analysis reveals that these N, S-CDs contain rich nitrogen, and sulfur as well as C=O and C=C functional groups. N, S-CDs had a mean size around 3-4 nm, very interestingly, obtained carbon dots exhibit excitation-dependent photoluminescent character, are water-soluble, and restore luminescent stability under UV-light exposure and a wide range of pH. The crafted N, S-CDs are hired for precise and discriminating detection of multiple water impurities such as Fe3+ ion and Picric acid. The complexation between oxygen species of N, S doped CDs, and Fe3+ ion follows the inner-filteration effect (IFE) and with Picric acid follows Forster Resonance Energy Transfer (FRET) for the doped N, S-CDs are found to be the utmost possible mechanism for the observed sensing performance. The lower detection limit (LOD) of Fe3+ sensors is about 0.11 µM and for picric acid is 0.07 µM. Moreover, these blue-emissive N, S-CDs as competent fluorescence sensors, have been used as fluorescent inks, as well as in advanced portable devices information security and filter paper-based probes for visual recognition might also hold prominent ability to make wider applications in biological systems.

UV light exposure versus vitamin D supplementation: A comparison of health benefits and vitamin D metabolism in a pig model

There is limited data on the effect of UV light exposure versus orally ingested vitamin D3 on vitamin D metabolism and health. A 4-week study with 16 pigs (as a model for human physiology) was conducted. The pigs were either supplemented with 20 µg/d vitamin D3 or exposed to UV light for 19 min/d to standardize plasma 25-hydroxyvitamin D3 levels. Important differences were higher levels of stored vitamin D3 in skin and subcutaneous fat, higher plasma concentrations of 3-epi-25-hydroxyvitamin D3 and increases of cutaneous lumisterol3 in UV-exposed pigs compared to supplemented pigs. UV light exposure compared to vitamin D3 supplementation resulted in lower hepatic cholesterol, higher circulating plasma nitrite, a marker of the blood pressure-lowering nitric oxide, and a reduction in the release of pro- and anti-inflammatory cytokines from stimulated peripheral blood mononuclear cells. However, plasma metabolome and stool microbiome analyses did not reveal any differences between the two groups. To conclude, the current data show important health relevant differences between oral vitamin D3 supplementation and UV light exposure. The findings may also partly explain the different vitamin D effects on health parameters obtained from association and intervention studies.

Developing and analyzing photo-crosslinkable cinnamoyl-modified pullulan hydrogels for drug delivery applications

A hydrogel created by modifying pullulan with cinnamoyl groups (Pul-CM) through an esterification process was developed as an effective vehicle for delivering the well-known drug model, caffeine. Initially, pullulan biopolymer was expanded, followed by the addition of cinnamoyl groups using cinnamoyl chloride. These modifications were confirmed through various spectroscopic and instrumental techniques, verifying their proposed chemical structures. The newly created Pul-CM hydrogel demonstrated the ability to crosslink without initiators when exposed to UV light for sufficient durations. This crosslinking is attributed to the creation of cyclobutane rings that link the pullulan chains via a [2π+2π] cyclization process facilitated by the cinnamoyl groups' –CH=CH– bonds. The progress of Pul-CM crosslinking was tracked by the reduction in the UV spectral peak associated with the cinnamate groups, followed by an examination of the gel's efficiency and its swelling behavior under UV light. Furthermore, these hydrogel derivatives show significant promise as drug delivery systems, offering adjustable drug release rates by altering the hydrogel's crosslinking level through either cinnamoyl modification or the duration of UV light exposure.

Enhancement-mode ZnGa2O4-based Phototransistor with high UV–visible rejection ratio grown by metalorganic chemical vapor deposition

In this study, a high-crystallinity zinc gallium oxide (ZnGa2O4) epilayer of about 80 nm thickness was successfully grown using metalorganic chemical vapor deposition. X-ray diffraction, atomic force microscopy, UV–visible spectroscopy measurements, and X-ray photoelectron spectroscopy were used to investigate the quality of the epilayer. Transmission line measurement analysis revealed the electrical properties of the ZnGa2O4 epilayer: a sheet resistance of 276 MΩ/□, a transfer length of 0.28 μm, and a specific contact resistivity of 21.63 Ω/mm2. A phototransistor made of ZnGa2O4 was designed with a channel width of 250 μm and a channel length of 20 μm. The source-drain electrodes were fabricated using a Ti/Al/Ni stacking technique. The gate dielectric comprised 30 nm thick Al2O3, and the gate contact was made of Ni. The device possessed a higher threshold voltage value of about 4.8 V and an impressive On/Off current ratio of 106. Under 240 nm UV light exposure, the phototransistor exhibited a transition from enhancement mode to depletion mode, leading to a remarkable shift in the threshold voltage from 5 V to approximately −16 V. Moreover, the responsivity and rejection ratio at 240 nm was 128.5 A/W and 105 at a gate voltage of −10 V. The study shows that an increasing thickness of the ZnGa2O4 epilayer from 80 nm to 135 nm results in a depletion mode transistor. The higher concentration of about twenty percent oxygen vacancies resulted in a longer fall time for the phototransistor. These results underscore the significant potential of ZnGa2O4 in facilitating deep UV-based detection applications.

Influence of Ultraviolet Light and Alternating Wet-Dry Environments on the Corrosion Behavior of Weathering Steels.

The corrosion behaviors of two bridge steels (Q345q and Q500q) under simulated ultraviolet irradiation and a wet-dry alternating (UVWD) environment were studied. Weight loss measurement, stereomicroscope observation, SEM, XRD, and electrochemical impedance spectroscopy (EIS) were performed to investigate the influence of the coupled environment. The results revealed that the corrosion rates of Q345q and Q500q were significantly accelerated by the synergistic effect of UV light exposure and alternating wet-dry conditions. Numerous voids and cracks could be observed throughout the thickened rust layers, enabling the corrosive substances to easily penetrate through the rust layer. Q500q exhibited better corrosion resistance than Q345q due to the addition of Mo, Cr, and Ni as corrosion-resistant elements, which tended to transform the rust layer into α-FeOOH rather than γ-FeOOH during later stages of corrosion.