Spectrophotometric Measurements Research Articles

Fabrication of epoxy composite coating with superior anticorrosive properties using a pH-responsive system based on 2D Zn-MOF nanosheets

Herein, two-dimensional Zn(Bim)(OAc) nanosheets (ZNS) were prepared using ultrasonication and surfactant-assisted methods. Subsequently, it was used as nanocontainer loaded with benzotriazole (BTA) corrosion inhibitor to fabricate BTA@ZNS nanocomposites with pH-controlled release characteristics. The morphology analysis exhibits that BTA@ZNS has a distinct lamellar structure. UV spectrophotometer measurements indicated the release rate of BTA reached 94.38% in 24h at pH=1. Adding BTA@ZNS as fillers into epoxy resin (EP) coating can form BTA@ZNS/EP composite coating with active anti-corrosion properties. Electrochemical impedance spectroscopy (EIS) demonstrates that BTA@ZNS/EP coating has superior corrosion resistance than other EP-based coatings. The enhanced anti-corrosion performance is ascribed to the barrier effect and acid-responsive controlled release of BTA@ZNS.

Comprehensive analysis of antioxidant and antibacterial activities of water and methanol extracts of Hibiscus flower

This study provides a comprehensive investigation into the antioxidant and antibacterial properties of Hibiscus flower extracts, highlighting their potential for future applications in functional foods. The research addressed key challenges by employing a multi-faceted approach, including four distinct methods for evaluating antioxidant potential: DPPH and FRAP assays, reducing power, and chelating ability of Fe ions. Total phenolic content was quantified using the Folin–Ciocalteu method, while tannins and flavonoids were assessed via vanillin–HCl and aluminum chloride assays. Additional analyses included spectrophotometric measurement of total flavonols and anthocyanins. Antibacterial activity was determined using a modified agar disk diffusion method, with results indicating significant inhibition of Salmonella typhimurium and Staphylococcus aureus by both aqueous and methanolic extracts. Colorimetric analysis revealed a reduction in chroma and hue angles, while FTIR spectroscopy identified key functional groups, such as suberin, lipids, and polysaccharides. Notably, the antioxidant efficacy varied depending on the solvent used, with aqueous extracts showing higher total phenolic content (4325.12 mg GAE/100 g) compared to methanolic extracts (3487.05 mg GAE/100 g). The study concludes that Hibiscus flower extracts, rich in antioxidants like tannins and anthocyanins, possess significant potential for use as natural preservatives and colorants in food products, supporting their role in developing novel functional foods.

Development of Titanium Dioxide Coating for Self-Cleaning Photovoltaic Panels

Amid escalating global energy demands and environmental concerns, the transition to renewable sources like solar power is imperative. Despite the advancements in photovoltaic (PV) technology promising increased efficiency, soiling on PV panels—composed of dust, bird droppings, and contaminants—poses a significant challenge, obstructing sunlight and reducing energy conversion efficiency. Building upon existing research on titanium dioxide (TiO2) nanoparticle coatings, our study investigates their super-hydrophilic and anti-soiling characteristics to enhance self-cleaning capabilities in solar applications. Furthermore, our research investigates the application of (3-aminopropyl)trimethoxy silane as an interlayer to reinforce the adherence of the TiO2 coating to PV panel glass, thereby enhancing its durability. Preliminary results highlight the coating’s exceptional super-hydrophilic properties, with water contact angle measurements less than 10°, indicative of TiO2’s strong water affinity. Spectrophotometer measurements show that the developed coating maintains high optical transmittances for the wavelength range from 350 to 800 nm, which is the most crucial factor for energy conversion in solar panels. Our contributions aim to advance solar energy technologies and support the shift towards more sustainable energy solutions, highlighting the role of innovative materials science in addressing solar power’s operational challenges.

Glucose-6-phosphate dehydrogenase deficiency detection using fluorocytometric assay: Evaluation after 1 year of clinical implementation.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common enzymopathy that affects red blood cells (RBCs) and renders them susceptible to oxidative stress. G6PD deficiency can cause hemolytic anemia, especially after exposure to certain drugs or infections. The diagnosis of G6PD deficiency is usually based on spectrophotometric measurement of enzyme activity, but this method has limitations in heterozygous females and in patients with other hematological disorders. In this study, we evaluated the use of flow cytometry as an alternative method for detecting G6PD deficiency in 514 samples (265 females and 249 males) from a clinical laboratory. We compared the results of flow cytometry with those of spectrophotometry and molecular analysis, and assessed the performance of flow cytometry in different subgroups of patients. We found that flow cytometry was able to identify G6PD deficiency in most cases, with high sensitivity and specificity. Flow cytometry also allowed the quantification of the percentage of G6PD-deficient RBCs, which varied among heterozygous females due to X-chromosome inactivation. Moreover, flow cytometry detected several cases of G6PD deficiency that were missed by spectrophotometry, especially in heterozygous females with normal or subnormal enzyme activity. However, flow cytometry also showed some false negative results, mainly in patients with sickle cell disease. Therefore, flow cytometry is a reliable and efficient tool for screening G6PD deficiency, but some precautions should be taken in interpreting the results in patients with other hematological conditions.

Soluble adenylyl cyclase is an acid-base sensor in rainbow trout red blood cells that regulates intracellular pH and haemoglobin-oxygen binding.

To identify the physiological role of the acid-base sensing enzyme, soluble adenylyl cyclase (sAC), in red blood cells (RBC) of the model teleost fish, rainbow trout. We used: (i) super-resolution microscopy to determine the subcellular location of sAC protein; (ii) live-cell imaging of RBC intracellular pH (pHi) with specific sAC inhibition (KH7 or LRE1) to determine its role in cellular acid-base regulation; (iii) spectrophotometric measurements of haemoglobin-oxygen (Hb-O2) binding in steady-state conditions; and (iv) during simulated arterial-venous transit, to determine the role of sAC in systemic O2 transport. Distinct pools of sAC protein were detected in the RBC cytoplasm, at the plasma membrane and within the nucleus. Inhibition of sAC decreased the setpoint for RBC pHi regulation by ~0.25 pH units compared to controls, and slowed the rates of RBC pHi recovery after an acid-base disturbance. RBC pHi recovery was entirely through the anion exchanger (AE) that was in part regulated by HCO3 --dependent sAC signaling. Inhibition of sAC decreased Hb-O2 affinity during a respiratory acidosis compared to controls and reduced the cooperativity of O2 binding. During invitro simulations of arterial-venous transit, sAC inhibition decreased the amount of O2 that is unloaded by ~11%. sAC represents a novel acid-base sensor in the RBCs of rainbow trout, where it participates in the modulation of RBC pHi and blood O2 transport though the regulation of AE activity. If substantiated in other species, these findings may have broad implications for our understanding of cardiovascular physiology in vertebrates.

Novel multi-function setup comprising ultra-bright uniform source for spectral and radiometric calibrations of digital imaging sensors and multiple spectrometric applications

Abstract A new setup is being developed for calibrating CCD/CMOS sensors and cameras, and measuring spectrophotometric quantities in both point-wise and imaging modes. The setup includes a laser-driven light source (LDLS), double-grating monochromator, and an integrating sphere with specific design for two-dimensional (2D) spectrophotometric measurements of complex samples and spectral responsivity calibration of digital imaging sensors and cameras in the visible to near infrared (VIS-NIR) region. The setup can cover a spectral range from 250 nm to 2000 nm with relatively high radiance. The study presents optimization and validation work in the visible through NIR spectral range, up to 1000 nm. Preliminary experiments suggest improved accuracy and lower uncertainties for better metrological performance and sophisticated applications. The developed instrument promises a variety of novel applications while suppressing systematic errors and inaccuracies. The presented measurements results include the validation of 2D spectral reflectance/transmittance measurements in the 360-1000 nm spectral region using selected homogenous standards. Additionally provided are the findings of demonstration measurements for 2D spectral transmittance and the CCD camera’s spectral responsivity within the same spectral range.

The Interaction of Nickel (II) Ion with Ethylene Diamine (en) Chelate Using Ethaline (Ionic Liquid) as a Solvent

For this experiment, this is the first time using 1 choline chloride (ChCl): 2 ethylene glycol (EG)based liquid (ethaline) to study the interaction between Ni (II) with ethylene diamine. Two of the optical methods for analyzing spectrophotometric measurements (continuous variations and molar ratio methods) have been utilized for determination of, the stoichiometry and whenever possible, the stability constants of the chelates formed. Job`s method was necessary to determine whether, the metal ion and the ligand ethylene diamine form one or more than one chelate, when more than one chelate formed, the results obtained depend on the maximum wavelength and for meaningful conclusions the wavelengths were carefully chosen. The empirical formulae of the chelates were further substantiated by the molar ratio method. The effect of time and temperature on the formation and stability of these chelates in solution is also investigated. The stability constants, K1, K2and K3 for the nickel (II) chelates were calculated by both optical methods, though reliable, and are comparable to literature values.

Preparation of Nano-Sized Eucalyptus Leaves Extract and its Application on Cotton as Natural Dyes and Antibacterial Agents

Nano-emulsions of Eucalyptus globulus leaves extract in 96% ethanol and 96% methanol were successfully prepared using the method of homogenization at various speeds of 13,000 rpm, 15,000 rpm and 17,000 rpm, with the addition of non-ionic surfactant to prevent agglomeration. A phytochemical analysis showed the presence of tannin, phenol and flavonoids. The size of the resulting nano-emulsions was measured using a particle size analyser (PSA) prior to the dyeing of cotton fabrics using the two-dips-two-nips method. Antibacterial tests were carried out on the extracts and dyed fabrics. The results showed that nano-sized particles (< 100 nm) were obtained from all extracts in both solvents used at all speeds. All dyed fabrics showed good levelness in a pale-brown colour with K/S values < 1 for all samples under spectrophotometric measurement. The colour fastness of the dyed fabrics to washing and rubbing were good to very good, with grey scale values ranging between 4/5–5. Antibacterial tests in Staphylococcus aureus bacterium showed that the eucalyptus leaves extract solution exhibited antibacterial ability, as evidenced by the formation of clear zones around the wells. Much better antibacterial activity was demonstrated by the dyed fabrics. Changing the particle size to nano increased the effectiveness of the antibacterial activity of the Eucalyptus globulus. Results showed that the nano-sized eucalyptus leaves extract demonstrated a more significant antibacterial activity than dyeability.

Wide spectral range optical characterization of niobium pentoxide ([formula omitted]) films by universal dispersion model

In this work, the optical properties of niobium pentoxide (Nb2O5) films were extensively studied across a wide spectral range using heterogeneous data-processing methods, combining ellipsometric and spectrophotometric measurements for five samples with thicknesses between 20 and 250 nm. This study primarily determined the optical constants of Nb2O5 from the far infrared to the vacuum ultraviolet, presenting these constants as dispersion parameters using the universal dispersion model to describe valence electron excitations in ultraviolet region as well as phonon vibrations in infrared region. These comprehensive and reliable data across such a broad spectral range are unprecedented. Secondly, presented optical characterization proofs that Nb2O5 films can be grown without defects such as surface roughness, porosity, or inhomogeneity. This fact, together with its high refractive index, makes Nb2O5 a promising material for optical applications.

Green synthesis of silver nanoparticles using carob leaf extract: Characterization and analysis of toxic effects in model organism Galleria mellonella L. (The greater wax moth).

Silver nanoparticles (Ag NPs) have been used in many studies due to their inhibitory properties on microorganisms such as bacteria and viruses. In recent years, due to global problems such as environmental pollution, the green synthesis (biosynthesis) method is frequently preferred because it is simple and low cost and does not require the use of toxic substances. The aim of this study is to synthesize silver nanoparticles (Ag NPs) from Ceratonia siliqua L. leaves and investigate their antioxidant and immunotoxic properties using Galleria mellonella last instar larvae. The UV spectrophotometer, TEM, XRD and FTIR measurements were used to characterize the Ag NPs. In this study, it was determined that the effects on antioxidant enzyme activities (SOD, CAT, GPx, GST), acetylcholinesterase (AChE) and total hemocyte count (THC) as well as phenoloxidase activity determine their effect on antioxidant defence and the immune system in model organism G. mellonella larvae. We observed that green synthesized Ag NPs accumulate in the midgut of the larvae and led to the increasing of CAT and SOD activities. GST and AChE activities were increased in the fat body of the larvae; otherwise, it was decreased in the midgut. Moreover, increases were found in THC and phenoloxidase activity. Consequently, green synthesized silver nanoparticles led to oxidative stress and immunotoxic effects on G. mellonella larvae.

In Vitro Study of Cyano-Phycocyanin Release from Hydrogels and Ex Vivo Study of Skin Penetration.

This study explored the most suitable materials for incorporating cyano-phycocyanin (C-PC) into hydrogels, focusing on maintaining the C-PC's long-term structural integrity and stabilityNext, the release of C-PC from the hydrogels and its skin penetration were investigated. A series of 1% (w/w) C-PC hydrogels was prepared using various gelling agents and preservatives. Spectrophotometric measurements compared the amount of C-PC in the hydrogels to the initially added amount. After selecting the most suitable gelling agent and preservative, two C-PC hydrogels, with and without propylene glycol (PG) (Sigma-Aldrich, St. Louis, MO, USA), were produced for further testing. In vitro release studies utilized modified Franz-type diffusion cells, while ex vivo skin-permeation studies employed Bronaugh-type cells and human skin. Confocal laser scanning microscopy analyzed C-PC accumulation in the skin. The findings demonstrated that sodium alginate (Sigma-Aldrich, St. Louis, MO, USA), hydroxyethyl cellulose (HEC) (Sigma-Aldrich, St. Louis, MO, USA), and SoligelTM (Givaudan, Vernier, Switzerland) are effective biopolymers for formulating hydrogels while maintaining C-PC stability. After 6 h, C-PC release from the hydrogel containing PG was approximately 10% or 728.07 (±19.35) μg/cm2, significantly higher than the nearly 7% or 531.44 (±26.81) μg/cm2 release from the hydrogel without PG (p < 0.05). The ex vivo qualitative skin-permeation study indicated that PG enhances C-PC penetration into the outermost skin layer. PG's ability to enhance the release of C-PC from the hydrogel, coupled with its capacity to modify the skin barrier ex vivo, facilitates the penetration of C-PC into the stratum corneum.

On analysis of structural and optical absorption characterization of Bi35Sb5Se60 nanostructured thin films for photosensing application

In this extensive study, the primary focus is directed towards the intricate exploration of the optical absorption characteristics inherent in nanostructured Bi35Sb5Se60 thin films, prepared by thermal evaporation under a vacuum of 10−5 Torr, ensuring high purity and uniformity for optoelectronic applications. With a particular emphasis on their prospective application in photosensing devices. The research employs a comprehensive approach, integrating various spectrophotometric measurements that encompass both transmission and reflection analyses. The meticulous examination of the absorption edge characteristics reveals a direct energy gap of 1.82 eV, providing a foundational understanding of the material's electronic structure. The determination of the dispersion energy at 6.35 eV and the oscillator energy at 2.96 eV further enriches the understanding of the material's optical behavior, shedding light on its capacity to interact with incident light. A noteworthy highlight emerges with the identification of high photosensitivity exhibited by the heterojunction, particularly under lower reverse bias conditions, underscoring its potential utility in photosensing applications. The PL spectra reveal a highly broadened defect emission band with peaks at 475 nm, 490 nm, and 540 nm, providing insights into the recombination processes within the material. The identification of emission peaks related to the conduction band edge and acceptor levels further enhances the comprehension of the material's optical and electronic characteristics. underscores the potential of these nanostructured thin films for efficient photosensing devices. The findings presented in this research not only advance the understanding of the material's properties but also lay a robust foundation for further research and development in the design and optimization of photoresponsive devices within the realm of optoelectronic technologies.

Substitution of additives in horseradish sauce: technological strategies and efficacy

An additive-free horseradish sauce was produced by replacing citric acid and sulfites, commonly used as acidifying, and antimicrobial/anti-browning agents, respectively. Unripe grape juice was used as acidifier, while steam blanching was applied to inactivate horseradish peroxidase (HRP) to avoid browning. Unexpectedly, the heat treatment inactivated myrosinase, responsible for the release of the irritating allyl isothiocyanate from sinigrin's hydrolysis, causing undesired loss of pungency. To restore it, mustard seed powder was added as an ingredient naturally rich in myrosinase. The inactivation of HRP and restoration of myrosinase were evaluated through spectrophotometric measurements of HRP and chromatographic analysis of glucose, a reaction product of myrosinase. The experimental sauce, obtained by adding basic ingredients to horseradish, was stabilized through pasteurization and subjected to sensory analysis and colorimetric evaluation. An additive-free and sustainable horseradish sauce was obtained, using mustard seeds and exploiting thinned bunches as by-products instead of wasting them.

The effect of seed layer cycles on the structural, optical, and morphological properties of ZnO nanorods.

In this study, ZnO seed layers with different cycles were formed on glass substrates by the sol-gel technique, and ZnO nanorods were grown on them by the hydrothermal method. Morphology and the structural characterization of the seed films and the ZnO nanorods are carried out by field emission scanning electron microscopy (FE-SEM) and x-ray diffraction techniques. In addition, to investigate the effect of seed layer deposition cycles on the optical properties of the ZnO nanorod arrays, UV/visible spectrophotometer and photoluminescence (PL) measurements were performed. The changes in structural and optical parameters such as dislocation density, strain, crystallite size, and optical band gap values on each seed layer deposition cycle were examined. The highest optical band gap and crystallite size were obtained for ZnO nanorods with 4 cycles seed layer as 3.22 eV and 63.6 nm, respectively. Also, in the PL spectrum, the largest ratio of UV-emission region to weak-visible emission region was obtained in ZnO nanorods having 4 cycles. In addition, the glucose detection properties of ZnO nanorods having 4 cycles were investigated using the PL measurements and it was found that UV-emission peak intensity of ZnO nanorods decreased as the glucose concentration increased from 8 to 40 mM. The results show that the number of deposition cycles of the seed layer has a strong influence on the orientation, crystal quality, and optical band gap of the growing ZnO nanorods, as well as significantly affecting their morphological properties. RESEARCH HIGHLIGHTS: High quality ZnO nanorods were grown on glass substrates by hydrothermal method. The effect of ZnO seed layer cycles on the structural, optical, and morphological characteristics of ZnO nanorods grown on were examined. It was found that the number of cycles of the seed layer is a critical parameter for growing quality and well-aligned ZnO nanorods.

Characterization of MoS2:Nb sputtered thin films. An application as hole transport layer in Cu2ZnSnS4/Si tandem solar cells

MoS2:Nb films deposited by radio-frequency magnetron sputtering are investigated in view of their application in infrared (IR)-transparent contacts for tandem photovoltaic devices.This material is already known to give a good electrical contact with p-type chalcogenide semiconductors, which are typically grown onto opaque molybdenum metallic contacts and a MoS2 layer spontaneously forms at the back interface during the on-top semiconductor growth. Our study explores a different approach, which involves the direct growth of IR-transparent MoS2:Nb films via sputtering inside complete photovoltaic devices, like Cu2ZnSnS4 (CZTS)-based single junction solar cells and CZTS/Si tandem devices. Films deposited at different sputtering pressures are compared by analysing their microstructure, morphology, chemical composition, optical and electrical properties. The effects of post-deposition sulfurization treatments are also investigated. We find that MoS2:Nb films deposited at around 0.1 Pa exhibit compactness but show a notable sulfur deficit ([S]/[Mo]≈1.4), a significant sub-bandgap optical absorptance and lack of crystallinity. Increasing the Ar pressure to 1 Pa raises the [S]/[Mo] ratio to 2.2, yielding crystalline films with good IR-transparency, although with a porous morphology. Despite 0.5 wt% Nb-doping of the sputtering target, the as-deposited films demonstrate n-type conductivity likely due to uncontrolled impurities and intrinsic defects. Ultraviolet Photoemission Spectroscopy measurements suggest that films’ work function higher than 5 eV can be obtained with a post-deposition sulfurization, making these materials suitable as Hole Transport Layer in photovoltaic applications. A similar increase in work function is expected in the CZTS/MoS2 junctions, since the sputtered MoS2:Nb films undergo a sulfurization process needed to obtain the overlying polycrystalline CZTS absorber.CZTS solar cells produced with sputtered MoS2 and Transparent Conductive Oxides contacts on glass substrates, despite plagued by severe adhesion problems, show the potentiality to give efficiencies comparable to reference devices with standard Mo back contact. Fabrication of CZTS/Si tandem devices on textured silicon bottom cells yields a maximum efficiency of 4.4 %, primarily hindered by the low quality of the CZTS film on textured substrates. Nonetheless, optoelectronic characterizations based on both spectrophotometric and quantum efficiency measurements confirm a good IR transparency of the MoS2-based intermediate contacts and the desired electrical behaviour.

Comparative analysis of cyto-genotoxicity of zinc using the comet assay and chromosomal abnormality test.

In this study, the toxicity of the trace element zinc (Zn) in Allium cepa L. test material was examined. Toxicity was investigated in terms of physiological, cytogenetic, biochemical, and anatomical aspects. Germination percentage, root length, weight gain, mitotic index (MI), micronucleus (MN) frequency, chromosomal abnormalities (CAs), malondialdehyde (MDA), proline and chlorophyll levels, superoxide dismutase (SOD) and catalase (CAT) enzyme activities, and meristematic cell damage were used as indicators of toxicity. Additionally, the comet test was used to measure the degree of DNA damage. Four groups of A. cepa bulbs-one for control and three for applications-were created. While the bulbs in the treatment groups were germinated with Zn at concentrations of 35, 70, and 140mg/L, the bulbs in the control group were germinated with tap water. Germination was carried out at room temperature for 72h and 144h. When the allotted time was over, the root tips and leaf samples were collected and prepared for spectrophotometric measurements and macroscopic-microscopic examinations. Consequently, Zn treatment led to significant reductions in physiological indicators such as weight gain, root length, and germination percentage. Zn exposure caused genotoxicity by decreasing the MI ratios and increasing the frequency of MN and CAs (p < 0.05). Zn promoted various types of CAs in root tip cells. The most observed of CAs was the sticky chromosome. Depending on the dose, Zn was found to cause an increase in tail lengths in comet analyses, which led to DNA damage. Exposure to Zn led to a significant decrease in chlorophyll levels and an increase in MDA and proline levels. It also promoted significant increases in SOD and CAT enzyme activities up to 70mg/L dose and statistically significant decreases at 140mg/L dose. Additionally, Zn exposure caused different types of anatomical damage. The most severe ones are epidermis and cortex cell damage. Besides, it was found that the Zn dose directly relates to all of the increases and decreases in physiological, cytogenetic, biochemical, and anatomical parameters that were seen as a result of Zn exposure. As a result, it has been determined that the Zn element, which is absolutely necessary in trace amounts for the continuation of the metabolic activities of the organisms, can cause toxicity if it reaches excessive levels.

Methanol extract of black garlic protects against hyperuricemia by xanthine oxidase inhibitory activity in-vitro

Garlic (Allium sativum L.) has been used as a medicative food for a long time. However, some individuals are averse to raw garlic owing to its pungent taste and aroma. As a result, a variety of garlic formulations have been created to minimize these characteristics without reducing their functions. Extensive in vitro and in vivo research has shown that black garlic has several benefits, including anti-oxidant, anti-inflammatory, anticancer, anti-obesity, anti-diabetic, anti-allergic, cardioprotective, and hepatoprotective characteristics. However, it remains unclear which compounds are active ingredients in the extract and the contributions of the main identified compounds to the extract's XO inhibitory activity are unknown. This study aims to look into the potent XO inhibitors found in black garlic methanol extract. The research methodology is experimental, involving the inhibition of xanthine oxidase activity, specifically measuring the amount of uric acid formed during the reaction catalyzed by xanthine oxidase. This is accomplished in vitro via enzymatic reactions and spectrophotometric measurements. The Maillard reaction is responsible for the production of black color in garlic, and it is influenced by heating temperature, humidity, and fermentation time. Starting on the 17th day of the fermentation process, the brownish intensity of the garlic samples heated at 70 ° C and 90% humidity changed to brown. The optimum concentration is 0.3 units/mL at an optimum temperature of 30oC and an optimum pH of 8.0 at a substratum concentration of 0.30 mM at a wavelength of 284 nm. The activity of the xanthine oxidase enzyme was inhibited by allopurinol at various concentrations, with allopurinol having the highest percentage inhibition value of 78.74 percent at a concentration of 10 ppm. The present study showed that meanwhile, the highest inhibition occurred on the 29th day of fermentation, with a percentage value of 68.01 percent, and decreased the next day

Adsorption of Selected Herbicides on Activated Carbon from Single- and Multi-Component Systems-Error Analysis in Isotherm Measurements.

The aim of this study is to examine the influence of various factors on the precision and repeatability of the experimental determination of herbicide adsorption isotherms. Studies were conducted for the activated carbon RIB as an adsorbent and three herbicides as adsorbates: 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chlorophenoxyacetic acid (4-CPA), and 3-chlorophenoxypropionic acid (3-CPP). The herbicide adsorption process was carried out in single-component and multi-component modes (the herbicide was adsorbed in the presence of an accompanying substance, i.e., 4-nitroaniline (4-NA)). Due to the significant contribution of the competition phenomenon in the adsorption process, which is important, e.g., in multi-component environmental systems, a qualitative and quantitative analysis of herbicide adsorption in the presence of a competing substance was presented. This work presents, among other things, the influence of adsorbent heterogeneity (grain size) on measurement uncertainties. The spread of standard deviations for solutions requiring dilution during spectrophotometric measurements was discussed, indicating that dilutions contribute to increasing measurement uncertainties. The heterogeneity parameters of the Freundlich equation for the studied adsorption systems were analyzed; the 2,4-D/RIB system was indicated as the most energetically heterogeneous. Differentiation of the experimental conditions (pH, temperature) allowed us to assess their impact on the efficiency and mechanism of adsorption. A high repeatability of experimental isotherms was obtained for the multi-component system. The accuracy of quantitative determination of equilibrium concentrations for the tested two-component systems was assessed based on the measured UV-Vis spectra, and the adsorption of herbicides from single- and multi-component systems was compared.

Color Modifications of a Maxillofacial Silicone Elastomer under the Effect of Cigarette Smoke.

Although it is known (from the observations of medical professionals) that cigarette smoke negatively affects maxillofacial prostheses, especially through staining/discoloration, systematic research in this regard is limited. Herein, the color modifications of M511 maxillofacial silicone, unpigmented and pigmented with red or skin tone pigments, covered with mattifiers, or with makeup and mattifiers, and directly exposed to cigarette smoke, were investigated by spectrophotometric measurements in the CIELab and RGB color systems. The changes in color parameters are comparatively discussed, showing that the base silicone material without pigmentation and coating undergoes the most significant modifications. Visible and clinically unacceptable changes occurred after direct exposure to only 20 cigarettes. By coating and application of makeup, the material is more resistant to color changes, which suggests that surface treatments provide increased protection to adsorption of the smoke components. The dynamic water vapor sorption (DVS) measurements indicate a decrease of the sorption capacity in pigmented versus unpigmented elastomers, in line with the changes in color parameters.

Stress factors and cytotoxic and genotoxic action of ethanol in Saccharomyces cerevisiae

In industrial fermentation, Saccharomyces cerevisiae are exposed to different stress conditions. In this sense, the aim of this study was to evaluate the toxic action of ethanolic stress on Saccharomyces cerevisiae. Exploratory research was carried out on the stress factors that cause injuries in yeast. Fermentation tests were conducted with the Fleischmann® and Pedra-2 strains, cultivated in sugarcane juice at 22 ºBrix and pH 5.0, adding concentrations of 5, 10, and 15% of ethyl alcohol, and incubated at 30°C at 250 rpm for 10 hours. For the cytotoxic tests, 100 µl of samples were collected for evaluation of cell growth by spectrophotometric measurements at 570 nm, and 5 µl were dripped into Petri dishes containing 2% YPD solid medium and incubated at 30ºC for 72 hours for colony growth. For the genotoxicity test, the comet test was used with 0.5 µl of the samples added to slides previously prepared and subjected to electrophoretic running and subsequently stained in a 0.1% silver nitrate solution. 100 random nucleotides were evaluated, evaluating five DNA damage classes (0, 1, 2, 3, and 4) according to the intensity and pattern of genetic material entrainment. The results show that stress factors interfere with yeast performance. Fleischmann® showed sensitivity to ethanolic stress.