Differences In Absorption Research Articles

Membrane distillation treatment of landfill leachate: Characteristics and mechanism of membrane fouling

Landfill leachate (LFL), which contains organic and inorganic contaminants in high concentration, poses a detrimental hazard to the ambient environment. Although membrane distillation (MD) shows great potential in wastewater treatment, the membrane fouling in LFL treatment is still a rarely reported. In this study, the membrane fouling was systematically investigated in a real LFL treatment by a direct contact MD system. Various characterization methods, such as scanning electron microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy were adopted in membrane fouling identification. Increasing membrane fouling was observed with the increasing feed pH. The analysis of membrane autopsy and differential log-transformed absorbance spectroscopy revealed that the increase of feed pH strengthened the deprotonation of carboxyl groups in organic matter, contributing to the formation of organo-inorganic complexation. The interaction between magnesium-related substances and humic-like matter might be the culprit of organo-inorganic membrane fouling in alkaline feed condition based on correlation analysis (R2 = 0.996). The results enhance the understanding of the mechanisms by which pH affects membrane fouling and lay the foundation for controlling membrane fouling in the LFL treatment.

Development of methods for citizen scientist mapping of residential woodsmoke in small communities

BackgroundResidential wood burning is a major source of fine particulate matter (PM2.5) during winter and a leading contributor to air pollution. Exposure to woodsmoke PM2.5 is associated with many health effects, so it is important to characterize the magnitude and spatial variability in exposures. However, high infrastructure and maintenance costs of regulatory monitoring stations limit their spatial resolution and make monitoring infeasible for many small communities where woodsmoke may be prevalent. MethodsMobile monitoring was conducted with a nephelometer and multi-wavelength aethalometer, capable of identifying woodsmoke PM2.5, to capture spatially resolved data. This Combined Aethalometer and Nephelometer for Assessment of Woodsmoke (CANAW) method was evaluated in three pairs of communities in British Columbia, Canada. Measurements were also taken at fixed-site monitoring stations. Light scattering measured by a nephelometer (Bsp) was compared with gravimetric filter-based and beta-attenuation measures of PM2.5. The difference in absorbance of 370 nm and 880 nm wavelengths as measured by an aethalometer (delta C), was compared with the chemical woodsmoke tracer levoglucosan. ResultsFixed site measurements of Bsp and delta C were comparable with established methods of monitoring PM2.5 and woodsmoke, respectively. Correlations in each tested relationship across all locations were high (r ≥ 0.93 in all cases). Mobile monitoring captured high spatial variation in woodsmoke PM2.5 and maps of average concentrations during monitoring were created to identify woodsmoke hotspots. ConclusionFollowing the successful implementation of the mobile CANAW method, training materials were created and tested with lay volunteers along with an online mapping application. Volunteers were able to effectively operate the equipment, collect valuable data on woodsmoke concentrations, and map spatial patterns across their communities using the application. The CANAW method is a valuable option for advancing cost-effective data collection for residential woodsmoke in otherwise unmonitored communities, and to add spatial context to existing monitoring networks.

Simultaneous determination of ofloxacin and bromfenac in combined dosage form using four different spectrophotometric methods

Four simple, precise, accurate and validated spectrophotometric methods have been developed for the simultaneous determination of ofloxacin (OFL) and bromfenac sodium (BROM). Firstly, first and second derivative spectrophotometric methods (1D &2D) using a zero-crossing technique utilizing 309.3 and 257.5 nm for OFL and 290.7 and 246.5 nm for BROM as optimum working wavelengths in a binary mixture, respectively. Secondly, the first derivative ratio spectrophotometric method (1DD) in which peak amplitudes at 297.3 nm and 260.7 nm were chosen to simultaneously estimate OFL and BROM, respectively. Thirdly, dual wavelength (DW) method based on two selected wavelengths for each drug in such a way that the difference in absorbance is zero for the second one. At wavelengths 296.4, 348.4 nm BROM has equal absorbance values, therefore, these two wavelengths have been used to determine OFL. Similarly, 271.7 nm and 313.1 nm were selected to determine BROM in the combined formulation. Finally, the fourth method depends on ratio difference spectrophotometry (RDSM), in which the difference between amplitudes at 305.6 nm and 326.5 nm on the ratio spectrum of the mixture was directly proportional to the concentration of OFL; independent of the interfering components. Similarly, the difference between amplitudes at 265.1 nm and 275.4 nm on the ratio spectrum was used for the determination of BROM.The linearity was confirmed in the range of 4 – 18 µg/ml for OFL and BROM for the four methods. The proposed methods were used to determine both drugs in their laboratory prepared mixture and combined formulation with mean percentage recoveries of 99.41 ± 1.35% for OFL and 99.98 ± 1.30 % for BROM in method (A). In method (B), the mean percentage recoveries were 101.70 ± 1.61% for OFL and 101.90 ± 1.45% for BROM. In method (C) OFL was 99.57 ± 1.61% and 100.90 ± 1.62% for BROM. Finally, in method (D) the mean percentage recoveries were 99.37 ± 1.67% for OFL and 100.70 ± 1.59% for BROM.The developed methods were successfully employed for determination of OFL and BROM in laboratory prepared mixtures and combined formulation showing satisfactory recoveries. Methods validation was performed according to the International Conference on Harmonization (ICH) guidelines. The obtained results conformed to the accepted ranges of recovery, precision and repeatability.

Phenolic Compounds, Vitamins C and E and Antioxidant Activity of Edible Honeysuckle Berries (Lonicera caerulea L. var. kamtschatica Pojark) in Relation to Their Origin.

Honeysuckles are frost tolerant plants providing early-ripening fruits with health-promoting properties which have been used in traditional medicine in China. This study evaluates the impact of the climatic conditions of two areas on the chemical composition and antioxidant activity (AOA; by DPPH—2,2-diphenyl-1-picrylhydrazyl and photochemiluminescence assays) of eight cultivars of honeysuckle berries (Lonicera caerulea L. var. kamtschatica Pojark) of various ripening times. Expectedly, chemical composition and AOA values varied depending on the cultivars, locality and selected methods. Berries from Lednice (the area with more sunshine) showed higher average contents of total monomeric anthocyanins (TMAC; pH differential absorbance method), vitamins C and E and total phenolics (high-performance liquid chromatography). In contrast, berries from Žabčice (the area with more rain) performed higher average contents of total phenolics and flavonoids (UV/VIS spectroscopic analyses). Interestingly, fundamental amounts of chlorogenic acid were determined irrespective of the locality. Regarding TMAC and vitamin C content, early ripening Amphora from both areas has been assessed as the best cultivar; concerning the content of phenolic compounds, Fialka from both areas and Amphora from Lednice is considered as the most valuable. The obtained results may facilitate the selection of the most valuable cultivars for both producers and consumers.

Identification of visible colored dissolved organic matter in biological and tertiary municipal effluents using multiple approaches including PARAFAC analysis

This study provided insights into the persistent yellowish color in biological and tertiary effluents of municipal wastewater through a multi-characterization approach and fluorescence excitation-emission matrix-parallel factor (EEM-PARAFAC) analysis. The characterization was performed on three to five full-scale municipal wastewater treatment plants (WWTPs), including differential log-transformed absorbance (DLnA) spectroscopy, resin fractionation, size-exclusion chromatography for apparent molecular weight analysis (SEC-AMW), and X-ray photoelectron spectroscopy (XPS) analysis. Hydrophobic acids (HPOA) were abundant in visible colored dissolved organic matter (DOM). The SEC-AMW result showed that the molecular weight of the colored substances in the secondary effluents is mainly distributed in the range of 2–3 kDa. Through XPS analysis, C-O/C-N and pyrrolic/pyridonic (N-5) were found to be positively correlated with chroma. PARAFAC component models were built on biological (two components) and tertiary effluent (three components) and the correlation analysis revealed that PARAFAC component 2 in biological effluent (BE-C2) and component 1 in tertiary effluent (TE-C1), which were ascribed to Hydrophobic acids and Humic acid-like, were the responsible visible colored DOM components cause yellowish color. In addition, component similarity testing found that the identified visible colored DOM PARAFAC BE-C2, and PARAFAC TE-C1 were identical (0.96) in physicochemical properties, with 4% removal efficacy on average, compared with 11% for invisible colored DOM. This implied that tertiary effluents containing colorants (TE-C1) were resistant to degradation/removal using different disinfection and filtration processes in advanced treatments. This sheds light on many physicochemical aspects of PARAFAC-identified visible colored DOM components and provides spectral data to build an online monitoring system.

Redefining the impact of preharvest factors on peach fruit quality development and metabolism: A review

One primary reason worldwide peach consumption has been in steady decline throughout the past few decades is due to poor fruit quality. Fruit quality is developed in the orchard by optimizing preharvest factors and orchard practices. Several studies have been conducted to understand how these factors influence peach internal quality, but often fail to control for confounding variables. One particular confounding variable that is influenced by preharvest factors and directly impacts fruit quality is maturation. Pomological experiments investigating the impact of preharvest factors on internal fruit quality must compare fruit of equal maturity. Maturity assessment through destructive and subjective methods is not feasible nor efficient. The use of visual radiation (Vis) and near-infrared spectroscopy (NIRS) allowed the development of robust non-destructive tools for physiological maturity (index of absorbance difference, IAD) and internal fruit quality [dry matter content (DMC) and soluble solids concentration (SSC)] assessment simultaneously in a single scan. Recent studies investigated the impact of critical preharvest factors such as rootstock, canopy position, crop load and growing environment on peach fruit quality development and metabolism, while selecting for fruit of equal maturity. Studies on rootstock and canopy position revealed that the fruit's light environment was more influential in quality development and metabolic shifts than the genotype vigor or position alone. Fruit under sufficient carbon supply, which was determined by crop load, exhibited superior quality and phenotype when compared to carbon-starved fruit at harvest. Although, metabolite profile differences between distinct carbon supply conditions at harvest were minimal, when assessed at equal maturity. Early metabolic shifts under optimum carbon supply and optimum growing environment conditions may prime fruit quality at harvest. Catechin and sorbitol were associated with high-quality fruit, while amino acids and citric acid showcased relationships with inferior quality fruit.

Intraoperative hyperspectral imaging (HSI) as a new diagnostic tool for the detection of cartilage degeneration

To investigate, whether hyperspectral imaging (HSI) is able to reliably differentiate between healthy and damaged cartilage tissue. A prospective diagnostic study was performed including 21 patients undergoing open knee surgery. HSI data were acquired during surgery, and the joint surface’s cartilage was assessed according to the ICRS cartilage injury score. The HSI system records light spectra from 500 to 1000 nm and generates several parameters including tissue water index (TWI) and the absorbance at 960 nm and 540 nm. Receiver operating characteristic curves were calculated to assess test parameters for threshold values of HSI. Areas with a cartilage defect ICRS grade ≥ 3 showed a significantly lower TWI (p = 0.026) and higher values for 540 nm (p < 0.001). No difference was seen for 960 nm (p = 0.244). For a threshold of 540 nm > 0.74, a cartilage defect ICRS grade ≥ 3 could be detected with a sensitivity of 0.81 and a specificity of 0.81. TWI was not suitable for cartilage defect detection. HSI can provide reliable parameters to differentiate healthy and damaged cartilage. Our data clearly suggest that the difference in absorbance at 540 nm would be the best parameter to achieve accurate identification of damaged cartilage.

The Influence of Rootstock on Fruit Ethylene, Respiration, Index of Absorbance Difference, Fruit Quality, and Production of ‘Aztec Fuji’ Apple under a Full-crop Condition

Selection of dwarfing rootstocks that facilitate optimum production of high-quality fruit is crucial in modern high-density apple orchards. In addition to tree growth and yield, rootstocks can influence fruit maturity of scion cultivars in apples. In this study, the impact of 17 rootstocks on fruit maturity, yield, and quality attributes of ‘Aztec Fuji’ apples (Malus domestica Borkh.) at harvest were evaluated in a season when all trees were in a “full-crop” condition. Keeping sealed fruit at room temperature, a typical climacteric pattern was observed in ethylene evolution, respiration, and oxygen consumption, peaking after 5–7 days in fruit from trees on all rootstocks. During the ripening period, ethylene evolution and respiration rates in fruit from trees on Supp.3, G.3001, and G.202 were often in the high-range category, whereas those on CG.4004, CG.4214, G.41N, and B.9 were in the midrange category and those on M.9Pajam2, M.26EMLA, and G.11 were in the low-range category. Evolved ethylene and respiration in fruit from trees on M9.T337 steadily and slowly increased from 7 days after harvest (7DAH) to 13 days after which harvest (13DAH) ethylene sharply increased, signaling occurrence of climacteric peak, while respiration declined after the peak of 13DAH. In fruit from trees on most rootstocks, the rates of oxygen consumption had inverse relationships with the rates of respiration, so that fruit from trees on M9.T337 had higher and those on G.41N and Supp.3 had lower rates of oxygen consumption. Trees on G.41N, CG.4004, and M.26EMLA had higher and those on CG.4003 had lower yield per tree than trees on other rootstocks. Trees on B.9 and M.9T337 were most yield efficient among trees on all rootstocks. Trees on CG.4004 had larger fruits than those on other rootstocks. Considering all fruit maturity, quality, and yield attributes, CG.4004 seems to be a good choice of rootstock for ‘Aztec Fuji’ under the conditions of this study.

Interband plasmon-enhanced optical absorption of DNA nucleobases through the graphene nanopore.

We propose a novel, to the best of our knowledge, plasmonic-based methodology for the purpose of fast DNA sequencing. The interband surface plasmon resonance and field-enhancement properties of graphene nanopore in the presence of the DNA nucleobases are investigated using a hybrid quantum/classical method (HQCM), which employs time-dependent density functional theory and a quasistatic finite difference time domain approach. In the strong plasmonic-molecular coupling regime where the plasmon and DNA absorption frequencies are degenerated, the optical response of DNA molecule in the vicinity of the nanopore is enhanced. In contrast, when the plasmon and nucleobases resonances are detuned the distinct peaks and broadening of the molecular resonances represent the inherent properties of the nucleobase. Due to the different optical properties of DNA nucleobases in the ultraviolet (UV) region of light, the signal corresponding to the replacement of nucleobases in a DNA block can be determined by considering the differential absorbance. Results show the promising capability of the present mechanism for practical DNA sequencing.

A peroxidase-like nanoenzyme based on strontium(II)-ion-exchanged Prussian blue analogue derivative SrCoO3/Co3O4 nanospheres and carbon quantum dots for the colorimetric detection of tigecycline in river water

In this work, for the first time, we derived a composite of perovskite oxide SrCoO3 and Co3O4 by annealing the Prussian blue analogue exchanged with strontium ions and modified with carbon quantum dots (CQDs). Its peroxidase-like catalytic activity was explored. The peroxidase-like activity was mainly evaluated by the rate of the chromogenic reaction. When H2O2 was present in the reaction system, the colorless substrate 3,3′,5,5′-tetramethylbenzidine (TMB) was oxidized into a blue product (oxTMB), and this was monitored by UV–vis absorption spectrum. Among them, the SrCoO3 and CQDs not only promoted the generation of superoxide anion radicals (O2−•) and electron-hole pairs (h+) in the reaction system, but also accelerated the electron transfer between the substrate TMB and H2O2. Therefore, the peroxidase-like catalytic activity of the reaction system was significantly improved. Moreover, the complexation of tigecycline (TGC) and CQDs@SrCoO3/Co3O4 composite enhanced the peroxidase-like catalytic activity of the reaction system. Based on this, using TGC and TMB as template molecules, a molecularly imprinted colorimetric sensor for detecting TGC was constructed. The absorbance difference of the reaction system was linear with the TGC concentration in the range of 0.02–6.0 μM, and the detection limit was 4.46 nM. Furthermore, the proposed sensor had high selectivity and applied to the detection of TGC in Pearl River water.

A preliminary study on characteristics of wideband acoustic immittance in patients with Meniere's disease

Objective:To explore the wideband absorbance characteristics of patients with Meniere's disease（MD）. Methods:Wideband acoustic immittance was performed in 52 patients with unilateral Meniere's disease（UMD） and 30 control subjects with normal hearing. All UMD patients underwent pure tone audiometry, 226 Hz acoustic immittance, wideband acoustic immittance, and gadolinium contrast MRI. Sixteen frequency points were chosen to analyze the wideband absorbance at ambient and peak pressure, and the subjects were grouped as UMD group vs. control group and asymptomatic group. The student's t-test was used to compare the absorbance difference between them. Results:Both at peak and ambient pressure, there was a significant difference between the MD group and control group at 1587 Hz, 2000 Hz, 2519 Hz, 3174 Hz, and 4000 Hz; the MD group was lower than the control group（P<0.05）; there were no differences between the asymptomatic group and the symptomatic group, there also was a significant difference between the asymptomatic group and control group at 1587-4000 Hz（P<0.05）. Conclusion:The wideband absorbance in MD patients was significantly reduced within the frequency range of 1587-4000 Hz, and wideband acoustic immittance seems to be cost-effective in predicting MD.

Impact of the anion on electrochemically doped regioregular and regiorandom poly(3‐hexylthiophene)

AbstractChemical and electrochemical doping of π‐conjugated polymers is an important aspect in determining the performance and enabling the operation of many organic electronic devices, from organic light emitting diodes and thermoelectrics to organic electrochemical transistors. In both chemical doping and electrochemical doping an ionized dopant or counterion is present along with the doped π‐conjugated polymer. This dopant or counterion is not a benign spectator, rather, its presence can significantly impact the optical, electronic, and thermoelectric properties of the resulting material. Here, we investigate how counterion structure impacts the electrochemical doping ability, oxidation potential, ionization energy, and polaron absorbance of regioregular (rr) and regiorandom (rra) P3HT. We find that in most cases the anion has a small effect on the polymer oxidation potential, except for in the case of rr‐P3HT with the large tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate anion. We propose that this large anion is excluded from the crystalline regions and thus the oxidation potential is similar to that of rra‐P3HT. The anions also result in significant differences in polaron absorbance and ionization energies, thereby emphasizing the important role of the counterion in determining the optical and electronic properties of doped π‐conjugated polymers.

Development of an Optical Method to Monitor Nitrification in Drinking Water.

Nitrification is a common issue observed in chloraminated drinking water distribution systems, resulting in the undesirable loss of monochloramine (NH2Cl) residual. The decay of monochloramine releases ammonia (NH3), which is converted to nitrite (NO2−) and nitrate (NO3−) through a biological oxidation process. During the course of monochloramine decay and the production of nitrite and nitrate, the spectral fingerprint is observed to change within the wavelength region sensitive to these species. In addition, chloraminated drinking water will contain natural organic matter (NOM), which also has a spectral fingerprint. To assess the nitrification status, the combined nitrate and nitrite absorbance fingerprint was isolated from the total spectra. A novel method is proposed here to isolate their spectra and estimate their combined concentration. The spectral fingerprint of pure monochloramine solution at different concentrations indicated that the absorbance difference between two concentrations at a specific wavelength can be related to other wavelengths by a linear function. It is assumed that the absorbance reduction in drinking water spectra due to monochloramine decay will follow a similar pattern as in ultrapure water. Based on this criteria, combined nitrate and nitrite spectra were isolated from the total spectrum. A machine learning model was developed using the support vector regression (SVR) algorithm to relate the spectral features of pure nitrate and nitrite with their concentrations. The model was used to predict the combined nitrate and nitrite concentration for a number of test samples. Out of these samples, the nitrified sample showed an increasing trend of combined nitrate and nitrite productions. The predicted values were matched with the observed concentrations, and the level of precision by the method was ± 0.01 mg-N L−1. This method can be implemented in chloraminated distribution systems to monitor and manage nitrification.

Authentication of cinnamon spice samples using FT-IR spectroscopy and chemometric classification

Cinnamon is a popular spice with a lengthy overseas supply chain. C. cassia is commonly traded as cinnamon, but the use of rapid methods to detect its adulteration has not yet been fully addressed. This work explores the use of FT-IR spectroscopy for the detection of adulteration in the cinnamon supply chain by several lower value ingredients. Two species of cinnamon (C. verum and C. cassia) and an adulterant (cinnamon spend, n = 2) were used to create 110 different in-house admixtures. Two different replacement fraud experiments were designed: C. cassia replaced with spend (Scenario A) and C. verum replaced with both C. cassia and spend (Scenario B). Initial analysis by GC-IMS showed promising differences between samples. The FT-IR spectra confirmed significant raw differences in absorbance. PCA for Scenario A demonstrated better separation than in Scenario B. The detection of adulteration of C. cassia (Scenario A) and C. verum (Scenario B) were equality accurate. Classification results showed that the PLS-DA technique was superior to SIMCA for both types of adulteration (PLS-DA: 94-90%; SIMCA: 83-79%, respectively). This demonstrates the potential of FT-IR as a screening method to identify cinnamon adulteration in supply chains and to provide accurate and rapid results without sample preparation.

Photoselective-Light Impacts on Fruit Bagging Microclimate, Quality, and Nutrients of Peach

The use of paper or nylon bags (fruit bagging) to surround tree fruit during development provides protection from a variety of pest-disease complexes for peach without yield reduction and different-colored bags have the potential to improve fruit quality based on findings from other crops. An experiment was conducted in 2019 at two locations in central Florida on peach [Prunus persica (L.) Batch] ‘TropicBeauty’ and ‘UFSun’ to analyze the impact of a commercially available white paper fruit bag combined with a photoselective insert. The insert reduced the amount of light outside the spectrum range of interest for blue (400–500 nm), green (500–600 nm), or red (&gt;600 nm) wavebands, or decreased fluence rate with a neutral density black (&gt;725 nm) insert. Relative to ambient, temperature inside all bagging treatments during the daytime hours was increased by 5.1 °C. During the same time, relative humidity was reduced by 10.1%, but calculations revealed that the water vapor pressure was elevated only for treatments that had a plastic colored (blue, green, or red) insert. An orthogonal contrast revealed that the elevated water vapor around the fruit in a colored bag increased the concentration of chlorophyll at harvest but had no effect on other quality parameters. Compared with unbagged fruit, red-bagged fruit were 1.8 times firmer and green-bagged fruit and had a lower peel chroma. White-bagged (without photoselective insert) fruit had similar nutrient concentrations for the peel, flesh, and pit when compared with unbagged fruit. When bags remained on the fruit until harvest, anthocyanin concentration in unbagged fruit peel was double the amount in white bags and 6-fold more than the bags with color inserts. Different-colored bagging treatments did not influence insect attraction or fruit quality parameters, such as fruit size, diameter, difference of absorbance (DA) index, total soluble solids (TSS), titratable acidity (TA), pH, peel lightness, peel hue, flesh lightness, flesh hue, or flesh chroma. Relative to full sun, the colored bag treatments allowed between 3.7% (black) and 17.4% (red) of the photosynthetically active radiation (PAR). Additional research is needed to determine if an increase in fluence rate at specific spectral wavelengths can affect the quality for peach grown in bags in the field.

Decision tree\u2013based identification of Staphylococcus aureus via infrared spectral analysis of ambient gas

In this study, eight types of bacteria were cultivated, including Staphylococcus aureus. The infrared absorption spectra of the gas surrounding cultured bacteria were recorded at a resolution of 0.5 cm−1 over the wavenumber range of 7500–500 cm−1. From these spectra, we searched for the infrared wavenumbers at which characteristic absorptions of the gas surrounding Staphylococcus aureus could be measured. This paper reports two wavenumber regions, 6516–6506 cm−1 and 2166–2158 cm−1. A decision tree–based machine learning algorithm was used to search for these wavenumber regions. The peak intensity or the absorbance difference was calculated for each region, and the ratio between them was obtained. When these ratios were used as training data, decision trees were created to classify the gas surrounding Staphylococcus aureus and the gas surrounding other bacteria into different groups. These decision trees show the potential effectiveness of using absorbance measurement at two wavenumber regions in finding Staphylococcus aureus.Graphical abstract

Detection of nitric oxide radical and determination of its scavenging activity by antioxidants using spectrophotometric and spectrofluorometric methods

Although reactive nitrogen species (RNS) may attack biomacromolecules and cause tissue damage when unbalanced by natural antioxidant defenses of the organism, they can also take part in cell signaling under different physiological states and defend against certain pathogens. Since there is a scarcity of analytical methods to detect radicalic NO and its scavengers, a functionalized gold nanoparticle-based spectrophotometric method and a spectrofluorometric method have been separately developed to test antioxidant activity toward scavenging of NO produced from sodium nitroprusside (SNP). The spectrophotometric method involves conversion of NO to nitrite, followed by the formation of an azo dye with 4-aminothiophenol (4-ATP)−modified gold nanoparticles (AuNPs) and N-(1-naphthyl)-ethylene diamine dichloride (NED) and its absorbance measurement at 565 nm. Calibration equations were established by taking the absorbance difference in the presence and absence of antioxidants. In the spectrofluorometric method, the excess of NO radicals, after being scavenged by thiol type antioxidants, caused a decrease in resorcinol fluorescence. The developed spectrophotometric method was applied to orange juice and its trolox equivalent (TE) antioxidant activity was found. By further applying the developed methods to real samples such as bovine serum albumin (BSA), fetal bovine serum (FBS), saliva and certain biomolecules, it is envisaged that these novel methods improving the selectivity of previous methods can be useful in human health and disease research associated with nitric oxide. The developed methods were compared and validated against the conventional Griess assay with Student t-test and F tests.

A preliminary study on the persistence of condom lubricants in the vaginal matrix

It has been established that condom traces are evidence to consider in sexual assaults and rape cases, but gaps in the interpretation of the evidence have been highlighted. Condom lubricants, more specifically silicone lubricants, are known to transfer in the vaginal matrix and can be easily recovered when analysed with infrared spectroscopy. The interpretation of condom evidence in forensic science requires a better understanding of mechanisms such as background, transfer, and persistence of the traces in a given matrix.This work aimed to use Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS-FTIR) to provide an empirical dataset addressing the persistence of transferred silicone lubricants in the vaginal matrix. Swabs for condom traces were self-collected from volunteers at different post-coital intervals ranging up to 36 h post-coitus. The effect of the time elapsed between the intercourse and the time of sample collection was investigated, and a preliminary observation of the activity of the claimant as an influence factor is also discussed.Silicones were easily detected up to 18 h post-coitus, while the vaginal matrix dominated the spectra after 36 h. At 24 h post-coitus, the results were not reproducible, which makes it difficult to assess a persistence at this time. The data were found to vary between the participants, but a similar trend was observed in the exponential decay. Finally, the activity of the volunteer was found to be one of the key parameters to the loss and differences in absorbance which were observed in the data. It was observed that when volunteers were taking a shower, which is likely to happen with real world cases, silicone persistence was also affected.

Dextran-stabilized Fe-Mn bimetallic oxidase-like nanozyme for total antioxidant capacity assay of fruit and vegetable food

The total antioxidant capacity (TAC) has become increasingly vital for evaluating antioxidant food quality in the field of healthcare. Herein, a convenient and sensitive method for TAC assay was proposed based on the absorbance difference of reaction systems between various antioxidants existed in food and Dex-FeMnzyme/oxTMB. Under the optimum condition, the limit of detection (LOD) of the colorimetric sensor was 1.17 μM with the linear concentration range from 1 μM to 30 μM. The analysis results demonstrated the excellent feasibility of practical application in fruit and vegetable food, which offered a new avenue for the establishment of colorimetric biosensors.

Controlled Lattice Thermal Conductivity of Transparent Conductive Oxide Thin Film via Localized Vibration of Doping Atoms.

Amorphization using impurity doping is a promising approach to improve the thermoelectric properties of tin-doped indium oxide (ITO) thin films. However, an abnormal phenomenon has been observed where an excessive concentration of doped atoms increases the lattice thermal conductivity (κl). To elucidate this paradox, we propose two hypotheses: (1) metal hydroxide formation due to the low bond enthalpy energy of O and metal atoms and (2) localized vibration due to excessive impurity doping. To verify these hypotheses, we doped ZnO and CeO2, which have low and high bond enthalpies with oxygen, respectively, into the ITO thin film. Regardless of the bond enthalpy energy, the κl values of the two thin films increased due to excessive doping. Fourier transform infrared spectroscopy was conducted to determine the metal hydroxide formation. There was no significant difference in wave absorbance originating from the OH stretching vibration. Therefore, the increase in κl due to the excessive doping was due to the formation of localized regions in the thin film. These results could be valuable for various applications using other transparent conductive oxides and guide the control of the properties of thin films.