Decrease In Absorbance Research Articles

Theoretical design of an electrically and thermally dual-controlled double-band absorber based on graphene and InSb

A novel, to our knowledge, double-band metamaterial absorber based on graphene and InSb is proposed in the terahertz regime. The amplitude and center frequency of the absorber can be electrically tuned by adjusting the graphene chemical potential and thermally controlled by varying the InSb temperature independently. First, owing to the bright–bright mode coupling effect, the average absorption rate of double-band absorber can reach 97% in the FDTD simulation. Meanwhile, the physical absorption mechanism can be analyzed theoretically by the radiating two-oscillator model. Second, when the chemical potential of graphene increases, the absorption rates of the absorber decrease gradually, and the absorption frequencies are almost unchanged. Moreover, if the temperature of InSb increases, the absorption frequencies and rates of absorber increase simultaneously. Finally, the impact of parameters on the absorption spectra, and the excellent sensing performance of the dual-band absorber as a refractive index sensor, are further discussed. This work provides a theoretical basis for the designs of dual-tunable absorbers and sensors.

A rapid colorimetric sensor for the detection of mercury in environmental samples employing 2 aminobenzohydrazide schiff base functionalized silver nanoparticles

Mercury (Hg2+) is an extremely toxic and dangerous element for living organisms. Herein, a simple and selective sensor based on the Schiff base of 2-aminobenzohydrazide with triazole thiazole substituted vanillin (EAHT) functionalized silver nanoparticles (EAHT-AgNPs) is proposed for the detection of Hg2+ in environmental water samples. The chemical reduction method was employed to synthesize EAHT-AgNPs using sodium borohydride as the reducing agent. The synthesized nanoparticles were initially confirmed by UV-visible and FTIR spectroscopy, followed by analysis with a zeta sizer to determine their average size, surface charge and polydispersity index. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to determine the size and morphology of EAHT-AgNPs. Additionally, the functionalized particles exhibited stability at varying pH values, salinity concentrations and elevated temperature. The addition of Hg2+ altered the yellow color of EAHT-AgNPs to colorless, confirming the complex formation. The analytical response constructed as a decrease in absorbance versus concentration showed linearity (R2 = 0. 991) from 0.1 to 100 µM with a limit of detection of 0.04 µM (40 nM) and limit of quantification of 0.085 µM (85 nM). The sensor was successfully applied for the detection of Hg2+ ions in tap water. In conclusion, Schiff base of 2-aminobenzohydrozide with triazole thiazole substituted vanillin silver nanoparticle-based chemosensor is highly sensitive and selective for the detection of Hg2+ in water samples. The proposed sensor has been applied for mercury detection tap water, future research should explore its applications in more complex samples like industrial wastewater and marine environments. Further, studies may focus on the integrating of the approach into the portable devices such as smartphone for on-site detection of mercury.

ATR-FTIR characterisation of daily-use plastics mycodegradation

Synthetic polymers, such as plastics, have permeated all aspects of modern life, and nowadays plastic pollution is a major environmental problem. Mycodegradation of these polymers could represent part of the solution to this problem since it calls on a broad toolbox of enzymes and applies non-enzymatic mechanisms to degrade and deteriorate recalcitrant materials. However, not enough is known about this ability for most of the representatives of the fungal kingdom. Another bottleneck is the harmonisation of technologies to analyse plastic degradation. This work involved the design of a biodegradation experiment, where the potential of four fungi representative of Dikarya and Penicillia (Funalia floccosa, Trametes versicolor, Pycnoporus cinnabarinus and Penicillium oxalicum) were tested on their ability to deteriorate the six most used plastics based on gravimetry and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The following correlation between changes in the band signals and the loss of mass after treatment was determined using polyethylene terephthalate, polypropylene, polyethylene, poly vinyl chloride, high density polyethylene, low density polyethylene and nylon. After treatment, the decrease in absorbance of the characteristic bands of the plastics was taken as an indication of the degradation of the corresponding bonds/functionalities. The four fungi used could transform CH, CH2, CH3, CO, CO, CN, NH and CCl bonds. The best result was obtained using the fungus F. floccosa with 90-day treatments for high density polyethylene (∼ 62.0 %), low density polyethylene (∼ 23.6 %) and nylon (∼ 35.6 %). Therefore, mycodegradation could open up new doors in the fight against plastic pollution.

Smartphone-assisted colorimetric detection of glutathione in food and pharmaceutical samples using MIL-88A(Fe)

Metal-organic frameworks (MOFs) have risen to prominence due to their unique structural features, including high porosity and tunable surface chemistry. As nanozymes, the MOFs replicate the catalytic activity of natural enzymes, thereby offering stability under diverse conditions and heightened efficiency. Glutathione (GSH) is a vital intracellular antioxidant and disease biomarker for cancer and neurodegenerative disorders. In this study, the intrinsic-oxidase activity of MIL-88A(Fe) was explored to develop a naked-eye-based colorimetric sensor for the detection of GSH. The 3,3′,5,5′,-tetramethyl benzidine (TMB) substrate was oxidized by MIL-88A(Fe), leading to the formation ofblue-colored oxidized TMB. The addition of GSH resultsin the reduction of oxidized TMB, causing the blue color to fade and a decrease in absorbance at 652 nm. Under optimal conditions, the developed sensor has a good linear relationship with GSH concentrations ranging from 0–40 μM with a detection limit of 150 nM. The developed methodwas successfully used to determine GSH accurately in real food and pharmaceutical samples. Further, the sensor demonstrated satisfactory performance for smartphone-based GSH detection on a paper-based assay. This work demonstrates the rapid, inexpensive, and ultrasensitive detection of GSH, opening new avenues for additional food quality and pharmaceuticalmonitoring.

Study of the Feasibility of Extracting Babassu Seed Oil by Extraction in an Ultrasonic Bath Using Organic Solvents

Introduction: Orbignia speciosa or phalerata (babassu) is an oilseed plant of great economic importance. The structure of the babassu fruit is similar to that of a coconut, and is composed of four parts: epicarp, mesocarp, endocarp and the seed, which contains approximately 60% oil, where lauric acid predominates in its composition, which is mainly responsible for the antiviral, antifungal and bactericidal activities of babassu oil. Babassu oil is a vegetable oil widely used in the food industry, and it also has wide application in the cosmetic, pharmaceutical and chemical industries. The objective of this work will be to use organic solvents in the extraction of oil from the babassu seed by the ultrasonic bath method with hexane, and with less toxic solvents such as ethyl acetate, isopropanol and ethanol. The kinetic curve of the extraction process will be determined to define the time required to reach saturation, establishing the time found as the ideal for the process. The fatty acid composition will be determined by gas chromatography. The antioxidant activity will be analyzed according to the adapted method of free radical capture by ultraviolet and visible spectrophotometry (UV-VIS). This method is based on the capture of the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical by antioxidants, producing a decrease in absorbance. After the interpretation and correlation of the results, it will be possible to establish the factors that present the best performance for the extraction of babassu oil and its chemical properties and compare them with the oil obtained using hexane. Objective: The objective of this study is to investigate the extraction of babassu seed oil with different organic solvents in order to evaluate the possibility of replacing hexane with a less toxic alternative solvent using the ultrasound extraction method. Theoretical Framework: A large amount of waste is produced by the food and agricultural industries, such as pulp, skins, seeds and fruit peels, some of which are considered by-products with a certain economic value. Babassu seed oil is rich in lauric acid, which has anti-inflammatory and immunomodulatory activities, among others. Method: The methodology used is experimental and applied in stages; the ideal oil extraction conditions were verified, the extraction was carried out using different organic solvents, the oil content obtained was quantified, the fatty acids were characterized, the antioxidant activity was determined using the DPPH method and finally the results obtained were compared. Results and Discussion: The oils obtained from the babassu seed through extraction in an ultrasonic bath with different organic solvents proved to be a promising by-product due to the characteristics evaluated. Research Implications: The oils obtained through organic solvents presented similar characteristics to those obtained with hexane, thus enabling its replacement due to it being a more toxic solvent. Originality/Value: This study contributes to the literature on vegetable oils extracted through green technologies with organic solvents, adding value to a by-product of a native fruit.

8226 A Diagnostic Challenge: Factitious Hypobicarbonatemia in Severe Hypertriglyceridemia

Abstract Disclosure: U. Rafat: None. S. Azmat: None. M. Siddiqui: None. R. Alshantti: None. D. Kircheva: None. V. Trendafilova: None. Background: Serum CO2 levels measured by a chemistry analyzer usually correlate with calculated bicarbonate levels on an ABG. There are some instances however, when this is not the case. Severe hypertriglyceridemia can cause serum bicarbonate levels to appear falsely low on metabolic panel. Clinical Case: A 48-year-old man was referred to Endocrinology Clinic for evaluation of hypogonadism and severe hypertriglyceridemia. Routine labs revealed a plasma CO2 of 11 mmol/L (20-31). Na was 133 mmol/L (136-145), K was 4.4 mmol/L (3.5-4.7), Chloride was 101 mmol/L (98-109) and anion gap was 25 (8-20) measured using a Siemens Vista enzymatic chemistry analyzer. His triglycerides were > 1100 mg/dL (0-150), above upper detection limits of the analyzer. The patient reported fatigue and mild abdominal pain. He was admitted to the hospital for further evaluation. His lipase was 41 U/L (12-73), lactic acid 1.2 mmol/L (0.50-2.20). ABG showed pH of 7.41, HCO3 of 26.6 mmol/L (22-29), and anion gap of 7 (10-20). The patient was well-appearing with normal vital signs and normal physical exam. He was made NPO and started on pravastatin, fenofibrate and fish oil. Once his triglycerides were < 1000 mg/dL, he was started on a very low-fat, low-carbohydrate diet. The CO2 level on BMP normalized on day 3 of hospitalization, when triglycerides measured 1010 mg/dL. No other treatment was given for the low CO2 levels. It does not appear that other lab indices were significantly affected by the hypertriglyceridemia. Review of Literature: A BMP measures serum total carbon dioxide using a chemistry analyzer using either an enzymatic/spectro-photometric method, or an electrode-based method; an ABG sample calculates plasma bicarbonate with the Henderson-Hasselbach equation, using the pH and partial pressure of pCO2 in the sample. Enzymatic analyzers measure CO2 using spectrophotometry and decrease in light absorbance is proportional to the sample’s CO2 levels. It is postulated that severely high triglycerides can interfere with this reaction and cause spuriously low CO2 levels, a phenomenon called pseudohypobicarbonatemia. One proposed mechanism for interference with the enzymatic assay method is turbidity causing a falsely low measured CO2 level. Verghese et al found that the severity of the CO2 measurement error positively correlates with the severity of triglyceride elevation. Conclusion: Awareness of the phenomenon of hypertriglyceridemia-induced pseudohypobicarbonatemia can prevent misdiagnosis or delays in diagnosis, as well as unwarranted testing and treatment. Presentation: 6/3/2024

A-083 Performance evaluation of Sentinel Diagnostics’ ACE assay on the Abbott Alinity c system and ARCHITECT c16000 System

Abstract Background The analytical performances of the Angiotensin Converting Enzyme (ACE) assay for quantitative determination of ACE activity in human serum and plasma have been evaluated on the Abbott Alinity c system and ARCHITECT c16000 System. ACE (dipeptidyl carboxypeptidase) is a glycoprotein peptidyldipeptide hydrolase that cleaves histidylleucine dipeptide from angiotensin I, a relatively inactive decapeptide. The latter is converted to the potent vasoconstrictor, angiotensin II. ACE also inactivates bradykinin. Elevated levels of ACE activity occur in serum of patients with active sarcoidosis, and occasionally in premature infants with respiratory distress syndrome, in adults with tuberculosis, Gaucher’s disease, leprosy, and in many other pathologic conditions involving lung and liver diseases. Methods ACE hydrolyses urylacryloylphenylalanine-glycylglycine (FAPGG) to furylacryloylphenylalanine (FAP) and glycylglycine. Hydrolysis of FAPGG results in a decrease in absorbance at 340 nm. The ACE activity in the sample is determined by comparing the sample reaction rate to that obtained with the Sentinel ACE calibrator. Performances evaluation have been done following the latest CLSI guidelines protocols available. Results Summary of the analytical performances for the tested assay is reported in table below. Conclusions Analytical performances of Sentinel Diagnostics’ ACE assay demonstrate that quantitative determination of ACE activity in human serum and plasma are suitable for the routine measurement of the analyte on Abbott Alinity c system and ARCHITECT c16000 System.

Effect of chitosan and natural materials on properties of polyvinylchloride for blood bags applications

Abstract Polyvinyl chloride is the most common material used in the manufacture of blood bags, and chitosan and wheat extract were used to improve the biological, physical, mechanical and optical properties of the manufactured blood bag. Chitosan was added at three concentrations (1, 2, and 3%) to the PVC matrix sample, and the wheat extract was supplemented to the sample having the highest properties to study its effect. It was found that the addition of chitosan led to an increase in tensile strength, as well as a significant increase in inhibition against the bacterial activity of two types of bacteria (S. aureus and C. albicans), and the ability to absorb water, but the addition of wheat extract led to a very small decrease in absorbency. Also, the supplement of chitosan and wheat extract reduced the transparency of the manufactured blood bag. All samples were characterized as not having the ability to non-hemolytic in the hemolysis test. All the results of polymer blends and polymer composite were compared with the pure PVC and commercial blood bags as reference samples.

Towards portable kits for on-site colorimetric detection of aqueous hydrazine using piperidine-thiophene-barbituric acid push-pull probe.

Owing to the carcinogenicity and environmental risks as well as the wide industrial use of hydrazine, we report herein a colorimetric probe for its ratiometric detection in pure water. The developed probe possesses push-pull architecture with 2-(piperidyn-1-yl)thiophene as the donor, N,N'-dibutylbarbituric as the acceptor, and butadiene as the spacer. In contrast to weak solvatochromic behavior in organic solvents, the probe showed distinct optical photophysical properties in water resulting from the formation of nanoscopic aggregates. The probe underwent pronounced spectral changes upon the addition of hydrazine including an 11.5-fold decrease in absorbance and ~2.4-fold fluorescence quenching. The mechanistic investigation revealed the rapid formation of hydrazone upon the interaction of the probe with hydrazine via retro-Knoevenagel reaction as confirmed experimentally and corroborated with DFT calculations. The induced colorimetric and fluorometric changes were utilized in hydrazine sensing with excellent selectivity over other biologically relevant analytes with a detection limit of 0.76 µM in aqueous media. The practical utility of the probe was assessed in real-life natural water samples, while we have also developed a cost-effective portable kit for the on-site hydrazine detection both in the solution and vapor phases.

A highly photostable UVA filter derived from avobenzone

Avobenzone was derivatized to avo-glycerol by replacing the p-methoxy group with glycerol at the ortho position. Avo-glycerol exhibited absorption in the UVA range (315–400 nm), similar to avobenzone, indicating good UVA coverage. Unlike avobenzone, a solution of avo-glycerol in an aprotic solvent demonstrates remarkable photostability, with no significant decrease in absorbance at the UVA range after 6 h irradiation. This suggests that the hydroxyl group in avo-glycerol functions as an efficient acid-base catalyst in enolization. Consequently, the rapid enolization of the photochemically generated keto form prevents its accumulation. This inherent photostability of avo-glycerol eliminates the need for photo stabilizers in sunscreen formulations and provides greater flexibility in selecting other sunscreen components.

Effects of opto-electronics properties of CeMnO2 nanoparticles improve the efficiency of CeMnO2/MAFASnBrI3/BaSi2 photovoltaic cells

In this paper, we synthesized manganese-substituted cerium oxide (CeMnO2) electron transport layer (ETL) nanomaterial via the co-precipitation method using various Mn compositions. These variations resulted in significant changes in the physical, optical, electronic, and dielectric properties of the CeMnO2 nanoparticles. The hexagonal structure of the CeMnO2 nanoparticles was validated using X-ray diffraction (XRD). Their morphology and surface characteristics were analyzed through scanning electron microscopy (SEM). Ultraviolet–visible (UV–Vis) spectrophotometry was utilized to explore their optoelectronic properties, revealing an increase in transmittance from 75 % to 90 %, along with corresponding decreases in reflectance and absorbance. Moreover, the energy bandgap (Eg) increased from 3.68 to 3.86 eV, while the Urbach energy (EU) rose from 0.18 to 0.6 eV with varying Mn compositions. The increase in defect quantity is associated with the reduction in both DC and AC conductivity observed with higher Mn compositions. Using a Hall effect instrument, we measured the sheet resistance, Hall mobility (ranging from 35.20 to 62.32 cm2 V−1 s−1), and carrier concentration (from 8.71 × 1018 to 1.22 × 1020 cm−3) of the CeMnO2 nanomaterials. The second stage focused on developing a high-efficiency (CeMnO2/MAFASnBrI3/BaSi2) solar cell based on experimental data from the CeMnO2 ETL and BaSi2 HTL materials. After multiple optimizations of the proposed solar cells, we achieved a 27.73 % efficiency.

Study of mesomorphic, thermal and optical properties of 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6) supramolecular hydrogen bonded mesogenic complexes

Within the scope of this study, the process of producing and analyzing a liquid crystalline substance (supramolecular hydrogen-bonded mesogen) is presented. The formation of this mesogen involves the use of two chemicals, namely 4-pentylbenzoic acid (5BA) and 4-n-alkyl-4́-cyanobiphenyl (nCB; n = 5, 6). Equimolar (1:1) 5BA/5CB and 5BA/6CB binary combination samples have been organized by using one at a time mixing 5CB and 6CB liquid crystal chemical substances with 5BA. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) are employed for the examination of phase transitions, and liquid crystalline phase texture properties of the produced mesogens. The phase transformation sequence that occurred during heating and cooling is Crystal (Cr) ↔ Smectic A (SmA) ↔ Nematic (N) ↔ Isotropic (I) with the 1st order or weakly 1st order transition. The nematic range value observed for 5BA/6CB is considerably smaller than the nematic range value observed for 5BA/5CB, but the thermal mesophase range value for both is approximately the same. Fourier-transform infrared (FTIR) evaluation of 5BA, 5CB, and their hydrogen-bonded combos (5BA/nCB; n = 5, 6) confirmed attribute peaks. The X-ray diffraction (XRD) study revealed that the produced mesogens possess a crystalline structure. In addition, UV–Vis experiments demonstrated that the increase in alkyl chain length in the combination resulted in a decrease in absorbance and wavelength values, while leading to an increase in absorbency and band gap energy values. These results propose workable purposes for the synthesized substances in liquid crystal displays and other optoelectronic devices. Overall, the findings display the feasibility and viability of these novel hydrogen-bonded liquid crystalline mesogens in various technological applications.

Synthesis, characterization, and azo dye degradation performance of mechanically alloyed Mg65Cu20Y13La2 nanocrystalline powders

This research describes the synthesis of the multicomponent Mg65Cu20Y13La2 alloy by mechanical alloying (MA) to investigate the influence of milling times on the microstructure of alloy and degradation performance of methyl orange. The structural evolution of this alloy was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDX) techniques. The thermal behavior of the alloys was investigated by differential scanning calorimetry (DSC). The crystallite size of the Mg65Cu20Y13La2 alloys was calculated using the Debye Scherrer equation with broadening of the XRD peaks. The methyl orange degradation efficiencies of the Mg65Cu20Y13La2 alloys were evaluated by using ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and gas chromatography–mass spectrometry (GC–MS) techniques. The XRD and SEM results showed that the microstructure of the powders changed during MA. After 10 h milling time, three intermetallic phases were obtained as Mg2Cu2La, Mg24Y5, and Mg2Cu. The results also showed that a solid solution phase, α-Mg(Cu, Y, La), with an average crystallite size 21 nm was formed after 100 h milling time. DSC trace of the Mg65Cu20Y13La2 powders showed two exothermic peaks for the 10 h milling time, while it did not show any peaks for the 100 h milling time. Photocatalytic decomposition of the methyl orange solution by the Mg65Cu20Y13La2 alloy was evaluated by UV–Vis spectra with a decrease in absorbance at a wavelength of 465 nm. After a 20 min exposure, UV–Vis, FT-IR, and GC–MS analysis showed that the methyl orange samples were almost completely degradation by using the Mg65Cu20Y13La2 powders. The Mg65Cu20Y13La2 alloy exhibits a good reusability of 92% by the four cycle and a high efficiency was achieved in all the pH values in the range of 5–9. The results prove that the Mg65Cu20Y13La2 alloy is an efficient and promising material for dyeing wastewater treatment.

Optical fiber LSPR sensor for SARS-CoV-2 N gene detection based on AuNRs

A novel SARS-CoV-2 N gene optical fiber biosensor based on ASO-coated gold nanorods is proposed in this work. A fiber probe prepared by AuNRs self-assembly was used to detect N gene by complementary base pairing method. The detected material was processed into AuNRs-ASO2-N gene coupler by cross-linking, and the pairing of N gene with ASO1 connected to AuNRs on the surface of the optical fiber formed the hydrogen bonding. The coupling of AuNRs resulted in a left shift of the peak position and a decrease in absorbance in the LSPR spectrum. In this manuscript, it is verified for the first time by simulation and experimental characterization that the coupling mode of AuNRs on the surface of the optical fiber is side by side, which leads to a left shift of the peak position of the LSPR absorption peak on the optical fiber. It is also proved that sandwich method is superior to the traditional method of changing the refractive index. The response time of the sensor is 10 min, and the detection limit is 1 pM, and the results show that the optical fiber sensor based on ASO-coated AuNRs has excellent RNA detection performance in artificial body fluids and is very suitable for RNA detection.

Realization of CO2 gas sensors and broadband photodetectors using metal/high-k CeO2/p-Si heterojunction

Realization of high-k dielectric oxide material-based devices such as photodetectors (PDs)/gas sensors fabricated on silicon substrate seems to be the utmost promising as a cost-effective approach to use in next generation optoelectronic field. We have explored metal/CeO2/p-Si heterojunction to construct as a broadband (BB) PD and CO2 gas sensor device. The effect of post-annealing procedure on photodetection and CO2 gas sensing characteristics were correlated using AFM, XRD, XPS, Raman and UV–Vis studies. At 0 V bias, the fabricated as-deposited Au/CeO2/p-Si PD device exhibits outstanding performance with enhanced responsivity of 85 AW−1 (at 910 nm), detectivity of 1.36×1015 Jones (at 850 nm), EQE of 1.3×104 % (at 850 nm), faster rise and fall times of 124 ms and 107 ms (at 900 nm). On the other hand, the photodetection characteristic parameters were slightly deteriorated as a function of annealing with respect to the as-deposited device. One of the causes for this fact was attributed to the increase in rms surface roughness (AFM) and decrease in absorbance of CeO2 thin film (UV–Vis). Additionally, Ag/CeO2/p-Si heterojunction was studied as a CO2 gas sensor and evaluated response/recovery times as a function of CO2 gas concentration. Sensing responses of CeO2 as-deposited, CeO2-400, CeO2-500, CeO2-600 and CeO2-700 °C were around 58, 60, 62, 81 and 90 %, respectively, when exposed to 200 ppm of CO2. Thus, we validate that the prospect of integrating enhanced performance in BB PDs and CO2 gas sensors using metal/CeO2/p-Si heterojunction could serve as a basic building block in near future optoelectronic applications. Furthermore, the effect of post-annealing temperature on the morphological, structural, BB photodetection and CO2 gas sensing properties were discussed in detail.

Effect of mass ratio on rGO/TiO2 composite as catalyst for methylene blue degradation under UV irradiation

Adsorption and photocatalytic are commonly used methods for the removal of dye contained in industrial wastewater. Therefore, this study aimed to combine reduced Graphene Oxide (rGO) with Titanium Oxide (TiO2) through various compositions using the hydrothermal method to obtain a catalyst of rGO/TiO2 nanocomposites for the removal of contaminants from wastewater. The synthesized rGO/TiO2 nanocomposites were mixed with methylene blue (MB) to reduce their content in water under dark conditions and UV light irradiation. The change of the optical properties of MB under both conditions was also examined, where a decrease in absorbance was observed. Under UV light irradiation, the maximum wavelength [Formula: see text] of MB shifted from 664[Formula: see text]nm to 649[Formula: see text]nm but remained constant at 664[Formula: see text]nm in dark conditions. The results of optical characterizations confirmed that the adsorption of MB by rGO/TiO2 nanocomposites under dark conditions did not change the MB structure. However, a significant degradation was observed with photocatalytic process under UV light irradiation. Nanocomposites rGO/TiO2 with rGO 60% and TiO2 40% (GT40) have better performance in reducing MB under UV light irradiation.

Influence of Ultrasonication Treatment on Mechanical, Optical, and Physiochemical Properties of Polyvinyl-alcohol/cornstarch Biocomposite Thin Films

Over the past few decades, Polyvinyl-alcohol (PVOH)/cornstarch (CS)-based composite thin films have garnered significant interest due to their enhanced properties. Synthesis of such films relies heavily on depolymerization reactions within the solution of the PVOH/CS blends. Understanding how depolymerization affects the crystal structure and properties of these films is crucial for further improvement. This study aims to evaluate the depolymerization effects of crosslinked PVOH incorporated with CS as filler materials (with an 80:20 mass ratio) using ultrasonication at various time intervals while maintaining a constant frequency of 25 KHz. The prepared solution is then cast into thin films using blade coating. Comparative analyses were then conducted between samples subjected to ultrasonication (treated) and without ultrasonication (untreated) to assess their properties based on structural physical, mechanical, optical, and aspects of biodegradability . The investigation revealed significant changes in crystal structure and lattice strains following ultrasonication of the PVOH/CS solution when compared to untreated PVOH/CS samples. Importantly, longer ultrasonication times correlated with increased tensile strength. Additionally, the treated samples led to improvements in thin film transparency and a notable decrease in absorbance. These changes were attributed to the mechanical depolymerization induced by ultrasonication, aligning the thin films with the necessary properties for food packaging applications.

Antioxidant and Anti-inflammatory Potential of Sargassum sp Extract in Lotion Preparations

Sargassum sp. is a type of brown algae found in Indonesian marine waters with great potential in the food and pharmaceutical industries. There is antioxidant and anti-inflammatory potential in Sargassum sp. extract so that it makes this type utilised as a lotion preparation. It is necessary to know the potential of Sargassum sp. extract in making lotions. This research uses extraction method to produce Sargassum sp. extract with organic solvent extraction technique, namely alcohol. In addition, the emulsion method was used in the manufacture of lotion preparations. Furthermore, secondary metabolites and anti-inflammatory (irritation) tests were conducted. In addition, the lotion preparation can be evaluated by conducting organoleptic, pH, and homogeneity tests. The results showed that the Sargassum sp. extract contained significant antioxidant compounds, as indicated by a decrease in DPPH absorbance. Sargassum extract contains alkaloid, flavonoid, saponin, and tannin. In addition, lotion preparations containing Sargassum sp. extract also showed a significant decrease in pro-inflammatory cytokine expression in skin cells exposed to UVB radiation. In addition, the irritation test showed negative results with a safety level without causing irritation to the skin. These findings indicate the potential of Sargassum sp. extract in producing lotion preparations with antioxidant and anti-inflammatory effects that can contribute to skin protection from oxidative damage and inflammation.

Bridging biological and food monitoring: A colorimetric and fluorescent dual-mode sensor based on N-doped carbon dots for detection of pH and histamine

Rapid and sensitive monitoring of pH and histamine is crucial for bridging biological and food systems and identifying corresponding abnormal situations. Herein, N-doped carbon dots (CDs) are fabricated by a hydrothermal method employing dipicolinic acid and o-phenylenediamine as precursors. The CDs exhibit colorimetric and fluorescent dual-mode responses to track pH and histamine variations in living cells and food freshness, respectively. The aggregation-induced emission enhancement and intramolecular charge transfer result in a decrease in absorbance and an increase in fluorescence, which become readily apparent as the pH changes from acidic to neutral. This property enables precise differentiation between normal and cancerous cells. Furthermore, given the intrinsic basicity of histamine, pH-responsive CDs are advantageous for additional colorimetric and fluorescent monitoring of histamine in food freshness, achieving linearities of 25–1000 µM and 30–1000 µM, respectively, which are broader than those of alternative nanoprobes. Interestingly, the smartphone-integrated sensing platform can portably and visually evaluate pH and histamine changes due to sensitive color changes. Therefore, the sensor not only establishes a dynamic connection between pH and histamine for the purposes of biological and food monitoring, but also presents a novel approach for developing a multifunctional biosensor that can accomplish environmental monitoring and biosensing simultaneously.

Photoproduction of Hydroxyl Radicals Under Sunlight by Fe-Zn Oxides for Partial Oxidation Applications

Iron-zinc oxide (FZ) photocatalysts with activity in the visible region were designed for the partial oxidation of organic molecules with the least loss of raw material. The FZ materials were synthesized using the sol-gel method with citric acid as a stabilizing agent. From TGA results, 400 °C was observed as the minimum temperature for precursors degradation, then two thermal treatment times were assessed at 60 and 180 min. The powder photocatalysts were comprehensively characterized by TGA, DSC, FTIR, XRD, Raman, Mössbauer, XPS, UV-Vis, and SEM. The production of hydroxyl radicals (•OH) was followed by the fluorescence emission of 2-hydroxy-terephthalic acid (OHTA). The absorbance decrease of methylene blue (MB) and disodium terephthalate (NaTA) was measured by UV-Vis spectroscopy to calculate the total degradation degree. The photocatalytic activity of FZ materials was quantified after 2 h under simulated sunlight radiation at room temperature conditions. All FZ oxides treated for 60 min presented no •OH detection, in which photocatalytic blanks showed an adsorption phenomenon of the probe molecules. FZ7 and FZ8 materials showed the best •OH production and the least MB/NaTA degradation, making them the best candidates for partial oxidation applications.