Monochromatic Ultraviolet Light Research Articles

Properties of Thin Film Composites of rGO–SnO2 and Modeling of Ultraviolet Laser‐Induced Conductivity Decay

AbstractReduced graphene oxide (rGO) and tin dioxide (SnO2) form composites in a wide range of SnO2/rGO proportions, which are deposited as thin films on borosilicate glass and silica substrates. The rGO proportion affects the SnO2 optical properties and the sample surface, as observed by optical transmittance and confocal and scanning electron microscopies images, mainly for high proportion of rGO. For low proportion, the presence of small surface islands may contribute to optical confinement. The evaluated bandgap is basically from the SnO2 matrix unless the presence of rGO affects the optical absorption edge. Monochromatic ultraviolet light from a He–Cd laser (325 nm) irradiating on the composite film increases the conductivity, giving rise to the phenomenon of persistent photoconductivity (PPC), even very close to room temperature. Modeling by considering mainly the SnO2/rGO interface barrier for electron transport, yield an interface energy barrier of 250 meV. The strong response to ultraviolet light and the phenomenon of PPC indicates potential application in amplifiers, which could be adjusted by doping with rare‐earth ions, such as Er3+ in the SnO2 matrix.

Titration curve for the determination of free lithium in a lithium-boron alloy

A simple and available method for identification and authentication of edible vegetable oils using a smartphone and chemometric analysis is presented. Identification of oils by the region of origin and species (olive, sunflower, rapeseed, cotton, etc.), as well as their authentication (authenticity and falsification) were carried out by the intrinsic color of vegetable oils and fluorescence under irradiation of the samples with monochromatic ultraviolet light (A = 365 nm). The iPhone X and iPhone XIII smartphones (Apple, USA) equipped with a specialized software (RGBer) were used as a color-recording device in the study of optical and colorimetric characteristics. A smartphone-based test device and a method for measuring colorimetric parameters in an additive RGB system for identification and authentication of edible vegetable oils are proposed. The processing of the data array (for three variables R, G, and B) was carried out using the XLSTAT software product. To differentiate the samples by the region of origin and species, the method of principal components and hierarchical cluster analysis were used. Approbation of the developed approach was carried out on the samples of commercially produced vegetable oils purchased in retail stores. The use of algorithms of chemometric analysis made it possible to establish the authenticity of vegetable oils, identify them by the region of origin, and to reveal facts of falsification by diluting expensive oils with cheaper ones. The developed method for assessing the quality of plant products is advantageous for the simplicity of hardware design, the availability of technical means and materials used, the possibility of in situ analysis without involving highly qualified specialists, and the clarity and speed of obtaining information.

Identification and Authentication of Milk Using Digital Colormetry of Indicator Test Systems, Smartphone, and Chemometric Analysis

A simple and an available method is proposed for the identification and authentication of milk using a test device, a smartphone, and chemometric analysis. For the identification by the region of origin and the species of milk (cow, goat, sheep, etc.) and authentication (authenticity, falsification of milk), acid-base indicator papers and test papers are used to determine the total hardness and total alkalinity of water and chloride and sulfate ions. Two indicator systems are proposed. In the first test system, 16 indicator zones are used, of which 12 zones are acid-base indicators with a color change in the pH range of 3–9, and 4 are indicator zones, the color change of which depends on the concentration of calcium ions and chloride, sulfate, carbonate, and hydrocarbonate ions. The second test system uses fluorescent indicators, as well as the intrinsic fluorescence of milk on cellulose paper and a thin silica layer. In this case, the indicator zones of the matrix are irradiated with monochromatic ultraviolet light (365 nm) after applying milk samples to them. A device and a method for measuring the colorimetric characteristics of test systems using a smartphone are proposed. The data array (the sum of the RGB channel values) is processed using the XLSTAT software. The use of chemometric analysis made it possible to establish the authenticity of milk, identify it by the region of origin, and reveal facts of milk falsification by dilution with water, the use of vegetable fats, and emulsification with surfactants. The manufacturers of pasteurized milk were identified and a possibility of determining its fat content by the data array of RGB colorimetric parameters is proved

DETECTION OF FALSIFICATION OF BUTTER BY COLORIMETRIC METHOD USING SMARTPHONE AND CHEMOMETRIC ANALYSIS

The paper proposes a simple and affordable way to identify and authenticate butter by a colorimetric method using a smartphone and chemometric analysis. Identification and authentication of dairy products was carried out by an analytical signal in the RGB colorimetric system when registering the intrinsic fluorescence of samples due to exposure to monochromatic ultraviolet light (365 nm). A test device based on a smartphone and a method for measuring colorimetric parameters in an additive RGB system for identifying and authenticating declared products of dairy origin are proposed. When studying colorimetric characteristics, iPhone X and iPhone XIII smartphones (Apple, USA) equipped with specialized RGBer software were used as a color recording device. The processing of the data array (for three variables R, G, and B) was carried out using the XLSTAT software product. The method of principal components and hierarchical cluster analysis were used to separate the samples by species (source of raw materials). Approbation of the presented approach was carried out on samples of commercially produced butter (32 samples) purchased in retail stores. The use of chemometric analysis methods made it possible to confirm the authenticity of the butter and reveal the facts of falsification. The results obtained correlated with the data of the arbitration method of gas-liquid chromatography in assessing the fatty acid composition of the fatty phase of the product. The proposed approach and its technical solution are characterized by the availability of component materials and digital equipment used in the operation of the test device. In addition, the mobility of the system and the ease of recording the colorimetric characteristics of the fluorescence of the analyzed object, combined with the clarity of the presented final information obtained using chemometric algorithms, makes this direction promising in monitoring laboratory and personal studies. For citation: Amelin V.G., Shogah Z.А.C., Bol’shakov D.S., Tretyakov A.V. Detection of falsification of butter by colorimetric method using smartphone and chemometric analysis. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 53-61. DOI: 10.6060/ivkkt.20236602.6717.

The use of smartphone and chemometric analysis for determination of tetracyclines in natural water by sensitized solid phase fluorescence of Eu on europium hydroxide

The possibility of identification and determination of tetracycline antibiotics (tetracycline, doxycycline, oxytetracycline, demeclocycline, metacycline and chlortetracycline) in natural water using digital colorimetry based on sensitized fluorescence of Eu (III) on europium hydroxide is studied. It is shown that complexes of Eu (III) with tetracyclines in an alkaline medium are adsorbed on europium hydroxide with preservation of their fluorescent properties. When the precipitate is irradiated with monochromatic ultraviolet light, pink fluorescence is observed. The colorimetric parameters of the precipitate in the RGB additive system after centrifugation were measured using a smartphone. The use of chemometric analysis provides shortening of the analysis procedure and visualizing of data obtained. The data set was processed using principal component analysis (PCA), hierarchical cluster analysis (HCA), and k-means method with XLSTAT software. The additional use of chemometric methods for processing of the analytical signal contributes to an increase in the reliability of the analyte identification. The methods used in the study make it possible to quantify the content of antibiotics in water bodies. The calibration dependences in the methods of principal components and k-means have a logarithmic form and are linear in the ranges of the determined contents — 0.005 – 0.1 μg/ml (R2 ≥ 0.99). The developed method for determining the total content of tetracycline antibiotics in natural waters is easy to use and is characterized by the availability of instrumentation. The environmental friendliness of this approach is attributed to a small set of inorganic salts required for concentration of the chelate complexes of tetracyclines with Eu (III) ions on europium hydroxide. The use of mobile digital technology (smartphones) and modern software products for data processing contributes to the development of rapid analysis. The approbation of the method was carried out using a sample of river water, the correctness of the analysis was proved by the spike test. The relative error of the analysis results does not exceed 15%.

Assessment of indigenous surrogate microorganisms for UV disinfection dose verification

AbstractThis study aimed to isolate waterborne heterotrophic organisms indigenous to water treatment processes with suitable ultraviolet (UV) dose–response profiles for estimation of the UV doses delivered by operational UV disinfection systems. The UV dose–response profiles of two isolated organisms, Flavobacterium succinicans and Sphingopyxis chilensis, were determined. S. chilensis has a UV dose–response with potential for use as an indigenous surrogate for Cryptosporidium inactivation, up to 2.2‐logs in the dose range 2–7 mJ/cm2 of monochromatic UV light at 253.7 nm. F. succinicans was more sensitive and tailing was observed above 4 mJ/cm2 making it unsuitable for UV dose verification above this dose. As a single species in the water samples used in this study, S. chilensis is unlikely to be present in sufficient numbers for routine use as an indigenous surrogate. However, the Sphingomonadaceae family to which it belongs is abundant in various drinking water sources and warrants further investigation.

Relative Ultraviolet Sensitivity of Selected Antibiotic Resistance Genes in Waterborne Bacteria

Abstract This study investigated the ability of monochromatic ultraviolet (UV) light at 254 nm applied at typical drinking water disinfection doses to damage the antibiotic-resistant genes mph(A), sul1, tet-A, and bla-Tem1 in waterborne bacteria. UV sensitivity rank was bla-TEM1 > tet-A > sul1 > mph(A), which is consistent with predictions of a previously presented genomic-based UV sensitivity model. It is the first time that predictions of the relative UV sensitivity of antibiotic resistance genes have been validated with experimental data and suggest that such modeling is useful for determining the UV sensitivity of other genes in waterborne microorganisms.

Balancing the Budget: Accounting for Glucocorticoid Bioactivity and Fate during Water Treatment.

Numerous studies have identified the presence and bioactivity of glucocorticoid receptor (GR) active substances in water; however, the identification and activity-balance of GR compounds remained elusive. This study determined the occurrence and attenuation of GR bioactivity and closed the balance by determining those substances responsible. The observed in vitro GR activity ranged from 39 to 155 ng dexamethasone-equivalent/L (ng Dex-EQ/L) in the secondary effluents of four wastewater treatment plants. Monochromatic ultraviolet light of 80 mJ/cm(2) disinfection dose was efficient for GR activity photolysis, whereas chlorination could not appreciably attenuate the observed GR activity. Ozonation was effective only at relatively high dose (ozone/TOC 1:1). Microfiltration membranes were not efficient for GR activity attenuation; however, reverse osmosis removed GR activity to levels below the limits of detection. A high-sensitivity liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was then developed to screen 27 GR agonists. Twelve were identified and quantified in effluents at summed concentrations of 9.6-21.2 ng/L. The summed Dex-EQ of individual compounds based on their measured concentrations was in excellent agreement with the Dex-EQ obtained from bioassay, which demonstrated that the detected glucocorticoids can entirely explain the observed GR bioactivity. Four synthetic glucocorticoids (triamcinolone acetonide, fluocinolone acetonide, clobetasol propionate, and fluticasone propionate) predominantly accounted for GR activity. These data represent the first known publication where a complete activity balance has been determined for GR agonists in an aquatic environment.

Orientation of migratory birds under ultraviolet light

In view of the finding that cryptochrome 1a, the putative receptor molecule for the avian magnetic compass, is restricted to the ultraviolet single cones in European Robins, we studied the orientation behaviour of robins and Australian Silvereyes under monochromatic ultraviolet (UV) light. At low intensity UV light of 0.3 mW/m(2), birds showed normal migratory orientation by their inclination compass, with the directional information originating in radical pair processes in the eye. At 2.8 mW/m(2), robins showed an axial preference in the east-west axis, whereas silvereyes preferred an easterly direction. At 5.7 mW/m(2), robins changed direction to a north-south axis. When UV light was combined with yellow light, robins showed easterly 'fixed direction' responses, which changed to disorientation when their upper beak was locally anaesthetised with xylocaine, indicating that they were controlled by the magnetite-based receptors in the beak. Orientation under UV light thus appears to be similar to that observed under blue, turquoise and green light, albeit the UV responses occur at lower light levels, probably because of the greater light sensitivity of the UV cones. The orientation under UV light and green light suggests that at least at the level of the retina, magnetoreception and vision are largely independent of each other.

Disinfection Methods for Treating Low TOC, Light Graywater to California Title 22 Water Reuse Standards

AbstractThis research was performed as part of the San Francisco Public Utilities Commission’s search for more sustainable water resources. Disinfection methods were evaluated for treating light graywater to California drinking water standards for unrestricted, direct nonpotable water use, indoors. Graywater originating from sinks and showers in a commercial office building in southern California was collected in grab samples over 4 weeks. Samples were filtered and tested for disinfection efficacy toward indigenous total coliforms and Enterococci as well as seeded male-specific 2 (MS2) coliphage. The filtered samples were exposed to monochromatic (253.7 nm) ultraviolet (UV) light, chlorination with sodium hypochlorite, and ozonation. A UV dose of 100 mJ/cm2 completely inactivated Enterococci and inactivated total coliforms to California drinking water standards required levels and achieved 5-log reduction of MS2 in half of the samples. Sodium hypochlorite met bacteria and virus standards for the graywate...

Photocatalytic degradation of olanzapine in aqueous and river waters suspension of titanium dioxide

The photostability of olanzapine, recently most commonly used atypical antipsychotic agent, was investigated. Two irradiation sources were applied, namely solar simulated light (E=250 and 500W/m2) and monochromatic ultraviolet light (λ=254 and 366). The olanzapine adsorption on a titanium dioxide surface was confirmed by differential scanning calorimetry and infrared spectroscopy. Kinetic studies were performed on a basis of a spectrophotometric method. Degradation efficiency was assessed by applying high performance liquid chromatography with an ultraviolet detection. HPLC analysis did not show any degradation products. Olanzapine was found to degrade under photocatalytic conditions with the creation of low molecular products. Disappearance of olanzapine from titanium dioxide surface after degradation was confirmed by IR spectra. A simple and promising way to apply the photocatalytic removal of olanzapine in titanium dioxide suspension was presented.

Metal ions/ion clusters transport in glassy polymer films: construction of multi-layered polymer and metal composite films

The addition of a metal complex and an additive to a polymer supported on a reflective surface, which was then exposed to monochromatic ultraviolet (UV) light, resulted in well-ordered metal nanoparticles. Their row spacing is similar to the distance between the constructive interference regions. This could occur even in glassy polymers. Transmission electron microscopy, absorption spectroscopy and dynamic secondary ion mass spectrometry in conjunction with molecular dynamics simulation all revealed how and why the metal ions and/or ion clusters were transported in the glassy polymer films. Furthermore, the diffusion coefficient of the metal ions and/or ion clusters in the film, probably in the shape of ion clusters, was discussed. Our results showed novel criteria to design and construct multi-layered polymer and metal composite films using a simple, inexpensive method.

A GaN photodetector integrated structure for wavelength characterization of ultraviolet light

An interesting GaN photodetector structure, which can be used for characterizing the wavelength of incident ultraviolet light, is proposed. It is composed of two back-to-back integrated diodes, i.e. p–n and p–i–n GaN ultraviolet photodiodes with different spectral response. The wavelength of monochromatic ultraviolet light could be identified by measuring the photocurrent ratio value through a simple electronic circuit.

Oxidative DNA damage in cucumber cotyledons irradiated with ultraviolet light

DNA was isolated from the cotyledons of cucumber seedlings irradiated with ultraviolet (UV)-C (254 nm) or UV-B+UV-A (280-360 nm; maximum energy at 312 nm) at various fluence rates and durations. Following enzymatic hydrolysis of DNA, the content of 8-hydroxy-2'-deoxyguanosine [(8-OHdG), 8-oxo-7,8-dihydro-2'-deoxyguanosine], a well-established biomarker closely identified with carcinogenesis and aging in animal cells, was determined using a high-performance liquid chromatograph equipped with an electrochemical detector. The levels of 8-OHdG increased with UV-C and UV-B irradiation in a fluence-dependent manner. This increase was also observed in etiolated cotyledons that had been excised from dark-grown cucumber seedlings and then cultured in vitro under UV light: monochromatic UV light at 270 nm or 290 nm increased the 8-OHdG level considerably, while UV at wavelengths above 310 nm had only small effects. In situ detection of H2O2 and quantification of H2O2 in plant extracts revealed that H2O2 accumulated in cotyledons irradiated with UV light. These results suggest that UV irradiation induces oxidative DNA damage in plant cells.

Multifunctional photochromic spiropyran dendrimers and their relaxation behaviors of photochromism

First and second generation dendrimers that exhibit unique photochromic behavior were synthesized through multi-step reactions. Their photochromic behavior under illumination of monochromatic ultraviolet light ( λ = 365 nm) was investigated. The colorless dendritic dye solution and its film exhibit typical ring opening and E/Z geometrical transformation from spiropyran to merocyanine. The stability of photochromism in the two dendrimers was much better than that observed in the dye-attached polymer or dye-doped polymer system. Particularly, blend material system of photochromic dendrimer and photocrosslinkable dendrimer showed much better stability of the photochromism.

UV disinfection of chlorinated water: impact on chlorine concentration and UV dose delivery

Prechlorination of water upstream of an ultraviolet (UV) disinfection process may possibly influence the effectiveness of UV inactivation through the absorbance of UV radiation. Alternatively, UV may act to destroy chlorine, reducing the residual in water. Monochromatic UV light was more effective in degrading monochloramine whereas polychromatic UV light was more effective in degrading free chlorine. The extent of degradation varied with the type of chlorine species, water quality and type of UV irradiation (mono- or polychromatic). However, decay of chlorine and monochloramine at typical UV disinfection doses (<100 mJ/cm2) was negligible. The transmission of UV irradiation was affected slightly by the presence of chlorine and monochloramine, and these effects on inactivation of MS2 coliphage were modeled for LP− and MP-UV reactors. The presence of 1 mg/L free chlorine or monochloramine decreased the inactivation of MS2 coliphage by less than 0.1 log for a LP-UV reactor. For the MP-UV reactor, MS2 inactivation decreased by between 0.1 and 0.3 log.

Molecular Beacon Probes of Photodamage in Thymine and Uracil Oligonucleotides¶

ABSTRACTMolecular beacons (MB) are becoming more common as sequence‐selective detectors of nucleic acids. Although they can easily detect single‐base mismatches, they have never been used to directly detect DNA or RNA damage. To measure the degree of ultraviolet (UV) light damage in oligonucleotides, we report a novel MB approach for general detection of photoproducts in UV‐irradiated rU17 and dT17 oligonucleotides. With monochromatic UV light irradiation at ca 280 nm under anoxic conditions, the oligonucleotide absorption decays with a single‐exponential time constant of 123 ± 1 min for rU17 and with double‐exponential time constants of 78 ± 0.5 min (99%) and 180 ± 5 min (0.05%) for dT17 oligonucleotides. Under the same conditions, the MB fluorescence decays more quickly, with single‐exponential time constants of 19 ± 2 and 26 ± 3 min for rU17 and dT17, respectively. Similar kinetics were observed with broadband UV light irradiation of oligonucleotides. The differences in the UV damage kinetics of dT17 and rU17 and their detection by absorption and fluorescence techniques will be discussed in the context of differential instabilities introduced in the nucleic acid‐MB duplex by the different photoproducts formed.

Molecular Beacon Probes of Photodamage in Thymine and Uracil Oligonucleotides¶

Abstract Molecular beacons (MB) are becoming more common as sequence-selective detectors of nucleic acids. Although they can easily detect single-base mismatches, they have never been used to directly detect DNA or RNA damage. To measure the degree of ultraviolet (UV) light damage in oligonucleotides, we report a novel MB approach for general detection of photoproducts in UV-irradiated rU17 and dT17 oligonucleotides. With monochromatic UV light irradiation at ca 280 nm under anoxic conditions, the oligonucleotide absorption decays with a single-exponential time constant of 123 ± 1 min for rU17 and with double-exponential time constants of 78 ± 0.5 min (99%) and 180 ± 5 min (0.05%) for dT17 oligonucleotides. Under the same conditions, the MB fluorescence decays more quickly, with single-exponential time constants of 19 ± 2 and 26 ± 3 min for rU17 and dT17, respectively. Similar kinetics were observed with broadband UV light irradiation of oligonucleotides. The differences in the UV damage kinetics of dT17 ...

Molecular Beacon Probes of Photodamage in Thymine and Uracil Oligonucleotides

Molecular beacons (MB) are becoming more common as sequence-selective detectors of nucleic acids. Although they can easily detect single-base mismatches, they have never been used to directly detect DNA or RNA damage. To measure the degree of ultraviolet (UV) light damage in oligonucleotides, we report a novel MB approach for general detection of photoproducts in UV-irradiated rU17 and dT17 oligonucleotides. With monochromatic UV light irradiation at ca 280 nm under anoxic conditions, the oligonucleotide absorption decays with a single-exponential time constant of 123+/-1 min for rU17 and with double-exponential time constants of 78+/-0.5 min (99%) and 180+/-5 min (0.05%) for dT17 oligonucleotides. Under the same conditions, the MB fluorescence decays more quickly, with single-exponential time constants of 19+/-2 and 26+/-3 min for rU17 and dT17, respectively. Similar kinetics were observed with broadband UV light irradiation of oligonucleotides. The differences in the UV damage kinetics of dT17 and rU17 and their detection by absorption and fluorescence techniques will be discussed in the context of differential instabilities introduced in the nucleic acid-MB duplex by the different photoproducts formed.

Standardization of Methods for Fluence (UV Dose) Determination in Bench-Scale UV Experiments

Ultraviolet (UV) disinfection is now an accepted technology for inactivation of a variety of waterborne pathogens in wastewater and drinking water. However, the techniques used in much of the previous research aimed at providing information on UV effectiveness have not yet been standardized. Thus in many peer reviewed published literature, it is not clear how the UV irradiations were carried out, nor how the average \Ifluence\N (or UV dose) given to the microorganisms has been determined. A detailed protocol for the determination of the fluence (UV dose) in a bench scale UV apparatus containing UV lamps emitting either monochromatic or broadband UV light was developed. This protocol includes specifications for the construction of a bench scale UV testing apparatus, methods for determination of the average irradiance in the water, details on UV radiometry, and considerations for microbiological testing. Use of this protocol will aid in standardization of bench scale UV testing and provide increased confidence in data generated during such testing.