Wavelength Ultraviolet Light Research Articles

Pharmacognostical evaluation and description of the leaf and root bark of Citropsis articulata Swingle & Kellerman

BackgroundCitropsis articulata Swingle & Kellerman (Family Rutaceae) is a renowned African traditional medicinal plant for the management of erectile dysfunction. The root bark is more commonly used than the leaves. Little has been done to evaluate the pharmacognostical parameters of both parts. PurposeThe aim of this study was to determine the pharmacognostical parameters of C. articulata leaves and root bark. MethodsThe plant parts were collected, washed, dried, and extracted by decoction and soxhlation. The World Health Organisation quality control methods for herbal materials were generally followed for the pharmacognostical evaluation of the root bark and leaf. This involved macroscopic and microscopic analysis, physicochemical analysis, hemolytic activity, and phytochemical analysis. ResultsMacroscopically, the distillate of the root bark showed a fluorescent blue colour under ultra violet light of wavelength 254 nm. Microscopic examination revealed the presence of cellulose, lignified, suberized and cuticular cell walls. Numerous aleurone grains were noted in the root bark. Phytochemical analysis showed the presence of reducing sugars, free amino acids, L-arginine, coumarin, glycosides, phenols, phytosterols, saponins, steroids, tannins, terpenoids, alkaloids and flavonoids. Thin layer and high performance liquid fingerprints were also developed. The C. articulata root bark decoction and Soxhlet extracts contained 12.35 ± 0.05, and 110.00 ± 0.03 while the leaf decoction and Soxhlet extracts contained 4.97 ± 0.03 and 39.65 ± 0.00 mg/g diosgenin equivalent saponins respectively. The L-arginine content for the dried root bark decoction and Soxhlet was 2681 ± 7.29, 1660 ± 2.99 µg/g, while that for the leaf decoction and Soxhlet extracts was 135.60 ± 8.28, and 130.20 ± 2.83 µg/g respectively. ConclusionThis study distinguished the root bark and leaf of Citropsis articulata and offered vital information for the quality control and standardization of the plant materials.

Ultraviolet irradiation enhances the nitration of allergens

Ultraviolet (UV) light is widely used for disinfection in indoor environments. Some wavelengths of UV light can produce high concentration of O3. UV irradiation combined with O3 may have great potential for nitration of allergens in the presence of NO2 in the air. In this study, the effects of UV irradiation on the nitration of three major indoor allergens including group Ⅰ allergens of house dust mite (Der p 1 and Der f 1) and group Ⅰ allergen of dog (Can f 1) in the presence of NO2 and O3 were investigated by analysis of the protein quantity, tyrosine, peptides, and nitration degree. The results showed that UV irradiation induced a significant increase in the quantity of 3-nitrotyrosine in the allergens from 0.4 ± 0.4 ng to 4.0 ± 0.8 ng. After 12 h of UV-O3 co-exposure, the total nitration degrees of the three allergens ranged from 0.1% to 0.5%, which were significantly higher than those after only O3 exposure (p < 0.05). The analysis of peptides revealed that the nitration of tyrosine was site-specific. The tyrosine Y231, which was adjacent to aspartic acid, posed the highest nitration degree of 41.1 ± 24.0% in Der p 1. The nitration degree of tyrosine Y162 was the highest (1.7 ± 0.1%) in Der f 1. Overall, this study demonstrated that UV irradiation enhanced the O3-related nitration of allergens in the air, which provides an experimental basis for the impact of daily disinfection behavior on allergens.

Evaluating hyperpigmentation: is invasion of the skin necessary?

BackgroundThe combination of long wavelength ultraviolet A1 radiation (LWUVA1) and visible light (VL) has been shown to produce photodamage and the majority of organic sunscreens lack protection against this spectrum. Currently, established testing protocols for VL photoprotection are lacking.ObjectiveTo compare pigmentation assessment methods, including Investigator’s Global Assessment (IGA) scoring, Diffuse Reflectance Spectroscopy (DRS), and immunohistochemistry, to assess the utility of each in evaluating VL + LWUVA1 induced pigmentation.MethodsAnonymized IGA, DRS, and immunohistochemistry data for 37 subjects (Fitzpatrick skin phototypes IV-VI) was retrospectively analyzed for pigment evaluation. Pigmentation was induced on the subjects’ backs with VL + LWUVA1 (0%–0.5% UVA1) irradiation at a dose of 480 J/cm2. Comparisons were made for all three assessment techniques between non-irradiated skin and VL + LWUVA1 irradiated skin, as well as between pure VL (0% UVA1) and VL + LWUVA1 (0.5% UVA1) irradiated sites. All comparisons were made for data collected approximately 24 h after irradiation to evaluate persistent pigment darkening (PPD).ResultsAmong all 37 subjects, both IGA scores and DRS detected a statistically significant difference in PPD between irradiated and non-irradiated sites, as well as between VL + LWUVA1 and pure VL irradiated sites. However, MART-1/Melan-A did not indicate a statistically significant difference in PPD between irradiated and non-irradiated sites or between VL + LWUVA1 and pure VL irradiated sites.ConclusionSubjective and objective noninvasive assessments were more sensitive in detecting VL + LWUVA1 induced pigmentation and should be preferred over invasive methods. Researchers are advised to initiate assessments with IGA and subsequently incorporate DRS for more objective and comprehensive insights in pigment evaluation.

The potential of 222-nm wavelength ultraviolet light for medical applications: a review

The potential of 222-nm wavelength ultraviolet light for medical applications: a review

Ultraviolet (UV) light effect on the electrical potential of interfacial water

Water is one of the most essential elements of life. Despite many studies on the physical and chemical properties of water, many features are still not yet understood. Here, we consider the negative electrical potential in the water adjacent to the Nafion membrane. The electrical potential becomes more negative closer to the membrane, a feature that might arise from the special water structure (interfacial water) next to Nafion. Evidence has shown that the water was characterized by a UV absorbance at ∼270 nm. We hypothesized that such radiant energy might contribute to the electrical potential of the interfacial water. Here, the effect of exposure to light on this potential, at wavelengths of 275 nm, 370 nm and 650 nm was studied. The electrical potential became more negative under 275 nm wavelength UV light, while other two wavelengths had negligible effects. The result fits well with the ∼270 nm wavelength absorption peak reported in previous studies. Potentially, the absorbed UV energy helps fuel the ‘water battery’. The findings shed light on the mechanism underlying the character of interfacial water adjacent to hydrophilic surfaces.

Enhancement of the Visible Light Photodetection of Inorganic Photodiodes via Additional Quantum Dots Layers.

Visible light photodetectors are extensively researched with transparent metal oxide holes/electron layers for various applications. Among the metal oxide transporting layers, nickel oxide (NiO) and zinc oxide (ZnO) are commonly adopted due to their wide band gap and high transparency. The objective of this study was to improve the visible light detection of NiO/ZnO photodiodes by introducing an additional quantum dot (QD) layer between the NiO and ZnO layers. Utilizing the unique property of QDs, we could select different sizes of QDs and responsive light wavelength ranges. The resulting red QDs utilized device that could detect light starting at 635 nm to UV (Ultra-violet) light wavelength and exhibited a photoresponsivity and external quantum efficiency (EQE) of 14.99 mA/W and 2.92% under 635 nm wavelength light illumination, respectively. Additionally, the green QDs, which utilized a device that could detect light starting at 520 nm, demonstrated photoresponsivity values of 8.34 mA/W and an EQE of 1.99% under 520 nm wavelength light illumination, respectively. In addition, we used X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) to investigate the origin of the photocurrents and the enhancement of the device's performance. This study suggests that incorporating QDs with metal oxide semiconductors is an effective approach for detecting visible light wavelengths in transparent optoelectronic devices.

Preparation of PW@CaCO3 phase change microcapsules modified by ZnO nanoparticles with excellent photocatalytic and thermal properties

We utilized an in-situ polymerization method to dope zinc oxide (ZnO) nanoparticles onto the surface of the inorganic calcium carbonate (CaCO3) shell capable of encapsulating paraffin wax (PW) cores, and synthesized a novel bifunctional microcapsule, which can be applied to optical catalysis and thermal energy storage. The PW@CaCO3/ZnO microcapsules with the varying ZnO nanoparticles were successfully synthesized. The micromorphology, chemical components, thermal properties, and photocatalytic applications of microcapsules doped with various ZnO concentrations were investigated. The results indicated that the PW@CaCO3/0.03%ZnO (i.e., the mass ratio of ZnO to PW of 0.03 wt%) exhibited the greatest thermal storage effectiveness and capacity with regard to all the samples. Under exposure to a particular wavelength of ultraviolet light, the PW@CaCO3/ZnO microcapsules can degrade the methylene blue dye solution by photocatalysis. The photocatalytic effect of the dye solution with PW@CaCO3/1.50%ZnO was the best after 12 h of exposure to ultraviolet radiation, and the degradation rate reached 98.97 %. In the spheres of energy conservation and environmental preservation, the PW@CaCO3/ZnO microcapsules offer a wide range of potential applications.

Rheological, Ballistic, and Mechanical Properties of 3D Printed, Photocured Composite Propellants

This study explores the rheological, mechanical, and ballistic properties of printed ammonium perchlorate composite propellant at 82.5% solids loading with binders curable with ultraviolet light of wavelength from 215 to 400 nm (UV). A polybutadiene urethane acrylate and two polyester urethane acrylate propellants are printed by an in-house-fabricated fused deposition molding printer. Propellants are all shear-thinning and have significantly lower viscosity than similar hydroxyl-terminated polybutadiene (HTPB) propellants. Uniaxial stress–strain measurements indicate that ultimate tensile strength and ultimate tensile strain of all photocurable propellants are found to be greater than HTPB propellant. In particular, the ultimate tensile strain of polyester urethane acrylate propellant is six times that of HTPB propellant, demonstrating high compliance. Ballistic properties are measured from combustion of printed propellant articles in a windowed Crawford combustion bomb at inert gas pressures of up to 12.1 MPa. The burning characteristics were found to be relatively planar, though strong burning rate anisotropy, expected as a result of print layer inhomogeneities, was observed in two of the three formulations. Overall, pressure exponents of the propellants were mild and ranged from 0.17 to 0.33. These results are compared and contrasted to those of other printed propellants. These results provide valuable insight into the selection of a safe binder system for printing of photocurable composite propellants.

Multi-channel Deep-UV absorbance measurement setup for multi-capillary electrophoresis with two fiber arrays facing each other

We have developed a simple, compact, and robust eight-channel ultraviolet (UV) absorption detection setup featuring two eight-fiber arrays (an irradiation fiber array and a detection fiber array) whose ends face each other across eight capillaries. UV light of a 220-nm wavelength from a single deuterium lamp is stably and evenly split into eight lights by using a thick homogenizing fiber connected to a fiber bundle with eight thin fibers, which make up the irradiation fiber array. Each capillary is directly irradiated with each UV light emitted from the irradiation fiber array and then each of the UV lights transmitted through the capillaries is collected by each fiber of the detection fiber array without using any other optical devices (e.g., a lens) and is detected by each of the eight photodetectors. This setup achieves simultaneous UV absorption measurement for all eight capillaries with the detection limit of 54 μAU, linear dynamic range of four logs or more, and negligible crosstalk of 0.01% or less. We also implemented an eight-capillary electrophoresis system and simultaneously analyzed eight immunoglobulin G samples, separated by capillary electrophoresis sodium dodecyl sulfate.

Comparison of Aflatoxin Yield from Peanut Isolate of Aspergillus flavus with Other Isolates

Background: Mouldy growth in food commodities by aflatoxin producing fungi is a serious health concern to animals as well as human beings due to the harmful effects of aflatoxins like hepatotoxicity, carcinogenicity, impairment of protein synthesis, formation of DNA adducts, etc. even in minute concentrations. A tropical climate with moderate temperature, high humidity and heavy rainfall provides optimal conditions for the growth of aflatoxin producing fungi like Aspergillus flavus in different food items. The current study was to examine if the substrate(s) in a food item has any role to play in aflatoxin production by A. flavus. Methods: The fungus was isolated from ten different edible materials and identified using standard procedure. The isolates were cultured in potato dextrose agar slants keeping the culture conditions identical in triplicates. The toxin extracted using chloroform as solvent and downstream processing to get crude toxin was quantified on the basis of dry weight. Thin layer chromatography was done and the fluorescence of the toxins from different isolates was visualised under high wavelength of ultra-violet light with standard Aflatoxin B1 chromatographed vis-a-vis to confirm presence of the toxin in all the extracted toxins. Result: Results of the extracted toxin dry weight comparison between different isolates as well as the fluorescence intensity in the chromatograms revealed that contaminated peanut isolate of A. flavus yielded the highest amount of crude toxin. Thus, the results indicate that there are some factor(s) in peanut that promote(s) aflatoxin production by A. flavus. This information was further used for formulating potato dextrose agar media for isolation of aflatoxin producing fungi by incorporating peanut extract in the media and comparing the amount of crude toxin yield.

Mechanism of Sodium Dodecyl Diphenyl Ether Disulfonate Filled Hydrotalcite Inhibiting the Photo-Degradation of Polyvinyl Chloride under Different Ranges of Ultraviolet Wavelength Irradiation

This content introduces a novel Ultraviolet (UV)-shielding material, Zn2Al-MADS-LDH (MADS-LDH), which was synthesized through co-precipitation method to insert sodium dodecyl diphenyl ether disulfonate (MADS) into the interlayer of Zn2Al-LDH layered double hydroxide (LDH), to improve the photoaging resistance of polyvinyl chloride (PVC). The characterization results indicated that MADS-LDH had a host-guest interaction between the LDH host layer and MADS guest anion, and it exhibited superior UV absorption capabilities than Zn2Al-CO3-LDH (CO3-LDH) and a broader absorption spectrum compared to MADS. A series of LDHs/PVC film composite materials containing LDHs nanosheets were prepared by incorporating the prepared LDHs into a PVC matrix via a solvent casting method. As expected, the MADS-LDH/PVC film composite materials exhibited enhanced photoaging resistance. The results of photoaging tests indicated that MADS-LDH inhibits the rate of carbonyl generation during photoaging of MADS-LDH/PVC film composite materials, resulting in a decrease in the carbonyl index (ΔCl) and relative degradation rate (RDR) compared to pristine PVC film and CO3-LDH/PVC film composite materials. Furthermore, the study evaluated the influence of different UV light wavelength ranges, such as UVB (280~315 nm), UVC (200~280 nm), and UV (200~400 nm), on the aging performance of PVC film and LDHs/PVC film composite materials. The results demonstrated that UV had the highest aging effect on PVC composite films, followed by UVC and UVB. Therefore, the MADS-LDH is a highly efficient and promising UV-shielding material with excellent potential for wide applications in the field of PVC.

The dependence of light extraction improvement on optimized surface microstructure for AlGaN-based UVC-LEDs considering TM-polarized emission

In order to improve the light extraction of AlGaN-based short wavelength ultraviolet light emitting diodes (DUC-LEDs), a type of microstructure with high aspect ratio is introduced and optimized on the AlN substrate surface. And, particle swarm optimization (PSO) algorithm is used to inverse design of the surface microstructure to maximize the light extraction efficiency (LEE). Considering that the propagation characteristics of TM-polarized light are different from that of TE-polarized light, the optical field distribution and LEE is analyzed for the UVC-LEDs with different TE-polarized component when the optimized surface microstructure is applied. Furthermore, the preparation process tolerance of the high aspect ratio structure is discussed by calculating the LED's LEE when the structural deviation occurs or morphology changes. Simulation results show that, by using the optimized surface microstructure based on parabola cone array, the LEDs' LEE is increased from 4.4% to 8.7% and from 0.4% to 3.7% for TE-polarized and TM-polarized emission, respectively. In addition, it is demonstrated that the light extraction improvement by the surface microstructure has a good tolerance to the structural deviation and morphology. The results are significant for improving light extraction and realizing high efficient short wavelength AlGaN-based UVC-LEDs by designing surface microstructures.

Effect of germicidal short wavelength ultraviolet light on the polyphenols, vitamins, and microbial inactivation in a highly opaque apple juice

AbstractThe aim of this investigation was to study the efficacy of UV‐C light emitting diode (LED) system operating at 263 nm for the inactivation of Listeria monocytogenes and Escherichia coli O157:H7. UV‐C irradiation was applied to stirred 5 ml samples, using a collimated beam LED system operating at a 263 nm wavelength. UV irradiation doses ranging from 0 to 160 mJ/cm2 were also delivered to apple juice (AJ) and polyphenols and vitamins were profiled. Liquid chromatography–mass spectrometry (LC–MS/MS) analysis was conducted to assess the stability of polyphenols or vitamins in UV‐C exposed AJ. The polyphenol and vitamin results demonstrated that UV‐C irradiation in AJs at relevant commercial UV doses induced significant reductions in the concentrations of selected polyphenols and vitamins, p &lt; .05. Ascorbic acid was reduced to 32%, at 160 mJ/cm2 whereas 17% reduction was observed at 40 mJ/cm2. Riboflavin was observed to be relatively stable. Epicatechin and chlorogenic were significantly reduced at high exposure doses. In contrast, minor changes were observed at 40 mJ/cm2. Results show that UV‐C irradiation effectively inactivated pathogenic microbes in AJ. Inactivation levels of all organisms were proportional to UV‐C dose. The log reduction kinetics of microorganisms followed log‐linear and with higher R2 (&gt;0.95). The decimal reduction dose (D10) values of 4.16 and 3.84 mJ/cm2 were obtained from the inactivation of E. coli and L. monocytogenes in AJ. The results from this study imply that adequate log reduction of pathogens is achievable in AJ and suggests significant potential for UV‐C treatment of other opaque liquid foods.

Preparation and Photocatalytic Activities of TiO2-Based Composite Catalysts

While modern industry has contributed to the prosperity of an increasingly urbanized society, it has also led to serious pollution problems, with discharged wastewater and exhaust gases causing significant environmental harm. Titanium dioxide (TiO2), which is an excellent photocatalyst, has received extensive attention because it is inexpensive and able to photocatalytically degrade pollutants in an environmentally friendly manner. TiO2 has many advantages, including high chemical stability, low toxicity, low operating costs, and environmental friendliness. TiO2 is an N-order semiconductor material with a bandgap of 3.2 eV. Only when the wavelength of ultraviolet light is less than or equal to 387.5 nm, the valence band electrons can obtain the energy of the photon and pass through the conduction band to form photoelectrons, meanwhile the valence band forms a photogenerated hole. And light in other wavelength regions does not excite this photogenerated electrons. The most common methods used to improve the photocatalytic efficiency of TiO2 involve increasing its photoresponse range and reducing photogenerated-carrier coupling. The morphology, size, and structure of a heterojunction can be altered through element doping, leading to improved photocatalytic efficiency. Mainstream methods for preparing TiO2 are reviewed in this paper, with several excellent preparation schemes for improving the photocatalytic efficiency of TiO2 introduced. TiO2 is mainly prepared using sol-gel, solvothermal, hydrothermal, anodic oxidation, microwave-assisted, CVD and PVD methods, and TiO2 nanoparticles with excellent photocatalytic properties can also be prepared. Ti-containing materials are widely used to purify harmful gases, as well as contaminants from building materials, coatings, and daily necessities. Therefore, the preparation and applications of titanium materials have become globally popular research topics.

P‐1.17: Ultraviolet Light Response of Amorphous Oxide Thin‐Film Transistors with Double‐Stacked Channel Layers

P‐1.17: Ultraviolet Light Response of Amorphous Oxide Thin‐Film Transistors with Double‐Stacked Channel Layers

INTERCEPT Pathogen Reduction in Platelet Concentrates, in Contrast to Gamma Irradiation, Induces the Formation of trans-Arachidonic Acids and Affects Eicosanoid Release during Storage.

Pathogen inactivation techniques for blood products have been implemented to optimize clinically safe blood components supply. The INTERCEPT system uses amotosalen together with ultraviolet light wavelength A (UVA) irradiation. Irradiation-induced inactivation of nucleic acids may actually be accompanied by modifications of chemically reactive polyunsaturated fatty acids known to be important mediators of platelet functions. Thus, here, we investigated eicosanoids and the related fatty acids released upon treatment and during storage of platelet concentrates for 7 days, complemented by the analysis of functional and metabolic consequences of these treatments. Metabolic and functional issues like glucose consumption, lactate formation, platelet aggregation, and clot firmness hardly differed between the two treatment groups. In contrast to gamma irradiation, here, we demonstrated that INTERCEPT treatment immediately caused new formation of trans-arachidonic acid isoforms, while 11-hydroxyeicosatetraenoic acid (11-HETE) and 15-HETE were increased and two hydroperoxyoctadecadienoic acid (HpODE) isoforms decreased. During further storage, these alterations remained stable, while the release of 12-lipoxygenase (12-LOX) products such as 12-HETE and 12-hydroxyeicosapentaenoic acid (12-HEPE) was further attenuated. In vitro synthesis of trans-arachidonic acid isoforms suggested that thiol radicals formed by UVA treatment may be responsible for the INTERCEPT-specific effects observed in platelet concentrates. It is reasonable to assume that UVA-induced molecules may have specific biological effects which need to be further investigated.

Ferrocyanide survival under near ultraviolet (300–400 nm) irradiation on early Earth

Prebiotic lake environments containing ferrocyanide could have fostered origins of life chemistry on early Earth. Ferrocyanide can act to concentrate hydrogen cyanide (HCN), a prebiotically important molecule. Additionally, ferrocyanide, coupled with sulfite, can participate in an ultraviolet (UV)-driven photoredox cycle to generate solvated electrons, which can reduce cyanide to form all four major building blocks of life: sugars, amino acids, nucleotides, and lipid precursors. However, longer wavelength UV light (∼300–400 nm) causes photoaquation of ferrocyanide into pentacyanoaquaferrate, Fe(CN)5H2O. This species can either regain cyanide to reform ferrocyanide or ultimately lose cyanide ligands, which removes ferrocyanide from solution. Here, we investigate this near ultraviolet (300–400 nm) UV-driven loss of ferrocyanide. In addition to determining the wavelength dependence of the loss and the implications from the UV environment on early Earth, we also study the effects of pH, temperature, and concentration. We find that in dilute, slightly alkaline solutions, ferrocyanide would degrade significantly on the order of minutes under the near UV radiation expected on early Earth. We further determine that the lifetime of ferrocyanide is extended at more alkaline pH, lower temperatures, and higher concentrations. Under a reasonable set of planetary conditions, we find that ferrocyanide lifetimes in irradiated environments range from minutes to hours, or longer. Our results can help to determine the constraints implied by the UV-driven loss of ferrocyanide in prebiotic environments. We assess the potential environmental limits and circumstances that would allow for successful retention of significant amounts of ferrocyanide in prebiotic lakes; we further evaluate how ferrocyanide photoaquation may fit in to the larger network of reactions potentially occurring throughout prebiotic chemistry. For example, our experiments show that CN- can be released from ferrocyanide evaporite salts by aqueous dissolution and UV light, making it potentially available for prebiotic reactions. These results can aid in the construction of consistent and plausible circumstances for prebiotic chemistry on early Earth.

Creativity of Nanofiber Materials and Application in the Expressive Power of Manual Tie-Dyeing Process

Traditional printing and tie-dyeing are an important part of Chinese handicrafts. It consists of three main techniques: batik, tie-dye, and multi-layer dyeing. Among the traditional printing and dyeing techniques, tie-dyeing creates an ever-changing visual artistic effect due to the diversity of its production methods. In modern society with the unprecedented development of technology and information, people’s life rhythm has accelerated, and the opposite “slow fashion” has become popular. More and more people are focusing more on the traditional craft of tie-dyeing. In contemporary fiber art, raw materials have become the soul and foundation of fiber art. This is also the difference between modern fiber art and traditional textile art. Entering the new era, the demand for textiles by people of all countries is also increasing, new functional requirements are put forward for textiles, and functional textiles emerge as the times require. The creative display of nanofibers is a comprehensive grasp of the properties of the fibrous material. It is the creativity and expression generated under the premise of understanding the type, shape, craft, and expression of fiber. It fully reflects the characteristics of the material itself, and it is also the designer’s ideological expression of the texture and shape of the material. It is then materialized into a certain connotation by appropriate technical means. In this paper, manual tie-dyeing is applied to nanofiber materials, making full use of the advantages of modern nanomaterials to promote the development of fabric tie-dyeing technology. In the performance test of the transmittance of nanomaterials to ultraviolet rays, it can be found that the transmittance of nanomaterials through the tie-dyeing process is lower for optical fibers with shorter wavelengths. When the wavelength of ultraviolet light is 313 nm, the transmittance of ZnO to ultraviolet light is 0. When the ultraviolet wavelength is 435 nm, the transmittance of ZnO to ultraviolet light is 45%.

A noticeable improvement in opto-electronic properties of nebulizer sprayed In2S3 thin films for stable-photodetector applications

In the present work, the versatile Indium sulfide thin film (In2S3) are deposited on glass substrates by using nebulizer assisted spray pyrolysis technique at 350 °C for ultra violet (UV) light detection application. The effect of the of indium and sulfur molar concentrations on the structure, morphology, optical characteristics, and photo-sensing capability of the prepared In2S3 films were systematically examined in the range of 0.01 M–0.03 M. The structural analysis of the 0.03 M sample showed a maximum crystallite size of 36 nm. The morphological image from the scanning electron microscope showed a homogeneous, large size grained surface of In2S3 completely covering the substrate. As the molar concentration was raised from 0.01 to 0.03 M, the indium to the sulfur ratio in the prepared films ranged from 1.02 to 1.16. All the prepared films showed good absorption in the ultraviolet region of the electromagnetic spectrum. The sample prepared at 0.03 M was found to have a minimum band gap of 2.38 eV and a maximum PL intensity at 680 nm. The I–V characteristics show a photocurrent of 1.4 × 10−5 A under UV light of wavelength 365 nm for an external bias voltage of ±5 V. A maximum responsivity of 2.74 A/W, detectivity of 2.65 × 1010 Jones was exhibited by 0.03 M sample with a high EQE of 63.9%. The prepared In2S3 thin film can be used as active material in photodetectors.

Which UV wavelength is the most effective for chlorine-resistant bacteria in terms of the impact of activity, cell membrane and DNA?

The widespread use of chlorine disinfectants in drinking water has accelerated the selection of chlorine-resistant bacteria (CRB). The presence of CRB in drinking water (during treatment, distribution, and consumption) has a profound impact on public safety. Ultraviolet (UV) irradiation is an effective control technology for CRB. Nevertheless, the relative efficacies of different UV light wavelengths (traditional mercury lamps, ultraviolet light-emitting diodes (UV-LED 265 nm and 285 nm), and 222 nm krypton-chlorine excilamps) in the control and inactivation of various CRB have not been investigated. In this study, the impacts of different UV light sources on the inactivation rate and microbial cell structure of CRB were evaluated. The results showed that the order of inactivation efficacy was as follows: UV-LED 265 nm > low-pressure ultraviolet (LPUV) ≈ medium-pressure ultraviolet (MPUV) ≈ 222 nm > UV-LED 285 nm. CRB was inactivated via DNA damage and additional ATP decline under UV-LED 265 nm, UV-LED 285 nm and LPUV irradiation, of which UV-LED 265 nm was the most effective based on fluence and inactivation rate constants. The inactivation mechanisms revealed that the 222 nm wavelength was significantly different from other wavelengths; it stimulated the production of a large number of reactive oxygen species (ROS) which resulted in bacterial cell membrane damage, ATP direct decline, and a small number of DNA lesions. Multispectral MPUV induced both of the foregoing mechanisms but mainly damaged DNA. The present study provides empirical evidence for the reasonable application of UV disinfection technology in the treatment of water and wastewater and their conduits and delivery systems.