Red Dye Solution Research Articles

Structural, optical, magnetic, and photocatalytic analysis of exclusive metal aluminates against Congo Red dye under UV light

The exclusive ZnAl2O4 (ZAO), CaAl2O4 (CAO), and MgAl2O4 (MAO) nanocrystallites were prepared by the citrate sol–gel route and further annealed at 600 °C for 2 h. XRD and Rietveld refinement were conducted to explore the crystal structure and to optimize the profile parameters. FTIR confirmed the vibrational peaks of relevant functional groups. The additional stretching and bending IR modes in MAO sample emphasized structural disorders like antisites/native defects. The UV-DRS spectra of these samples analyzed the direct bandgap in 2.76–4.29 eV range. HR-TEM micrographs characterize the well-developed nanosized grains. From VSM data, several magnetic parameters were collected for prepared aluminates and found MAO as best ferromagnetic material with the highest coercive field value (1235 Oe). PL spectra of metal aluminates suggest that the broad peak in violet-blue is attributed to the band edge emission, and finite peaks in higher wavelength regions have appeared due to the large density of surface traps and oxygen vacancies. The photocatalytic mechanism of ZAO, MAO & CAO nanopowder was elucidated on the Congo Red dye (10–70 ppm) solution after exposure to UV light. The highest value of rate constant (k = 0.0118 min−1) suggests that the MAO (0.3 g l−1) sample would be an efficient photocatalyst (98%) under UV light owing to its large surface area (125 m2 g−1) and suitable bandgap. The overall results advocate the practical applicability of aluminate photocatalysts in water treatment, spintronics, and photonics.

Evaluation of Freezanz automated misting system against mosquitoes

Automated misting systems are a convenient way for homeowners or small businesses to control adult mosquitoes. One such system was presented to the Anastasia Mosquito Control District (AMCD) for evaluation to control caged Aedes aegypti. The system consisted of 3 spray tanks, 2 pumps, water level sensors, and flow meters, and was controlled through an Android tablet loaded with dedicated control software. The evaluation of the system included calibration tests, droplet characterization, spray dispersion in the open field, and effectiveness testing using bio-assay cages for mortality assessment. For these tests, a loop of 14 nozzles 4 m apart was connected and held at 1 m height utilizing a total of 120 m tube. All nozzles were arranged in a 16 × 12 m rectangle laid in the East-West direction. Water was sprayed for calibration and droplet size measurements at pressures of 13.0, 15.5, and 18 bar; water and 10 % red dye solution for spray dispersion at 18 bar pressure, and 0.17 % solution of equalizer 20–20 was sprayed at 18 bar pressure for mortality tests. All 3 replicated tests were conducted in the morning between 9:00 and 11:30am. During this time, temperature ranged from 21 to 26 °C, relative humidity from 54 to 95%, and wind speed from 0 – 2 km/hr.The combined flow rate from all 14 nozzles was significantly affected by pressure and was in agreement with the machine-calculated flow rate. There was a similar flow rate from all nozzles, indicated by a standard error of 0.82 mL/min. The droplet characteristics represented by DV0.1, DV0.5, and DV0.9 were not affected by nozzles but decreased with an increase in pressure as expected. The percentage of coverage on the cards, an indicator of spray dispersion, ranged from 20 -100%, and it was found to increase in the direction of the wind. Mosquito mortality showed a similar trend of increasing in the wind direction and ranged from 30 to 100 %. There was no effect of the location of cages on mosquito mortality. These results indicate that the effectiveness of this spray depends upon wind direction. The results, however, may be different when there is no wind, which may be the case during the times these applications are made.

Synthesis of AZO-Coated ZnO Core-Shell Nanorods by Mist Chemical Vapor Deposition for Wastewater Treatment Applications.

AZO-coated ZnO core-shell nanorods were successfully fabricated using the mist chemical vapor deposition method. The influence of coating time on the structural, optical, and photocatalytic properties of zinc oxide nanorods was investigated. It was observed that the surface area of AZO-coated ZnO core-shell nanorods increased with an increase in coating time. The growth orientation along the (0001) crystal plane of the AZO thin film coating was the same as that of zinc oxide nanorods. The crystallinity of AZO-coated ZnO core-shell nanorods was significantly improved as well. The optical transmittance of AZO-coated ZnO core-shell nanorods was greater than 55% in the visible region. The degradation efficiency for methyl red dye solution increased with an increase in coating time. The highest degradation efficiency was achieved by AZO-coated ZnO core-shell nanorods with a coating duration of 20 min, exhibiting a degradation rate of 0.0053 min-1. The photodegradation mechanism of AZO-coated ZnO core-shell nanorods under ultraviolet irradiation was revealed.

One-Step Hydrothermal Synthesis of Cu2ZnSnS4 Nanoparticles as an Efficient Visible Light Photocatalyst for the Degradation of Congo Red Azo Dye.

A hydrothermal method was successfully employed to synthesize kesterite Cu2ZnSnS4 (CZTS) nanoparticles. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and optical ultraviolet-visible (UV-vis) spectroscopy were used for characterization of structural, chemical, morphological, and optical properties. XRD results confirmed that a nanocrystalline CZTS phase corresponding to the kesterite structure was formed. Raman analysis confirmed the existence of single pure phase CZTS. XPS results revealed the oxidation states as Cu+, Zn2+, Sn4+, and S2-. FESEM and TEM micrograph images revealed the presence of nanoparticles with average sizes between 7 nm to 60 nm. The synthesized CZTS nanoparticles bandgap was found to be 1.5 eV which is optimal for solar photocatalytic degradation applications. The properties as a semiconductor material were evaluated through the Mott-Schottky analysis. The photocatalytic activity of CZTS has been investigated through photodegradation of Congo red azo dye solution under solar simulation light irradiation, proving to be an excellent photo-catalyst for CR where 90.2% degradation could be achieved in just 60 min. Furthermore, the prepared CZTS was reusable and can be repeatedly used to remove Congo red dye from aqueous solutions.

PHOTOCATALYTIC DEGRADATION OF REACTIVE RED DYE AND OPTIMIZATION OF THEIR EXPERIMENTAL FACTORS

Box-Behnken design of experiment for the optimization of the experimental parameters of the photocatalytic degradation of reactive red dye using dye concentration (mg/L), catalyst dosage (mg/L), pH and time of exposure as experimental factors was studied and reported. Stock solution of reactive red dye was prepared (0.00001M) and serial dilution was used to prepare twenty-seven (27) different concentration of the dye solution which were subjected to photocatalytic degradation in a photo reactor using a ultraviolent light source under ambient environmental condition. The absorbances of these solutions before and after photo degradation was taken to obtain different percentage degradation for each experimental run. Analysis of these results was carried out using minitab 17 computer software. The result reveals the optimized conditions for the photodegredationas 10mg/L (dye concentration), 1mg/l (catalyst dosage), 5.85 pH and 90 minutes (time of exposure). This was confirmed experimentally after the optimization to prove that minitab17 software is highly effective for the optimization.

Decolorisation of Reactive Congo Red Dye Solution by Electro Coagulation Process

The decolourisation of the reactive Congo red dye from synthetic wastewater was studied using ElectroCoagulation (EC) technique. In an effort to increase removal efficiency, the effects of operating parameters including flow, inter electrode distance, conductivity, voltage, and Hydraulic Detention Time (HDT) were investigated. An electrochemical cell was initially created with an aluminum cathode and anode. Following that, each variable's impact was examined independently using synthetic wastewater. The colour removal efficiency was 93% when the initial dye concentration was 4 mg/L, the conductivity was 300 ppm, the temperature was 24 oC, the interelectrode spacing was 1 cm, and the HDT of the electrolysis was 120 min.

The Preparation and Nonlinear Properties Study of a Mixture of Polyurethane and Neutral Red Dye Solution.

A mixture of polyurethane (PU) and neutral red (NR) dye solution is prepared. The nonlinear optical properties of the mixture of PU with NR dye solution are studied using a 473nm laser beam of continuous fashion. The nonlinear refraction index of prepared material is determined via diffraction patterns and Z-scan. The diffraction patterns are calculated based on the Fresnel-Kirchhoff integral. Optical limiting of the prepared material is tested. All-optical switching occur in the sample using two low power visible laser beams.

Astrazon Red FBL Çözeltisinin Gama Işınlarıyla Renk Giderimi ve Detoksifikasyonu

In this study, decoloration and detoxification of Astrazon Red FBL dye solutions using gamma rays have been examined at different environments (air, O2 saturated, 2.6 mM H2O2). In this context, the decoloration, mineralization, detoxification, pH, COD and BOD5 parameters were followed. Biodegradability ( 5 days of biological oxygen demand/ chemical oxygen demand -BOD5/COD-) ratio has been improved up on 2 kGy irradiation for all solutions. Optimum irradiation conditions were found to be 5 kGy pH 9 for air, 5 kGy pH 11 for O2 saturated, 7 kGy pH 11 for 2.6 mM H2O2 to provide mineralization and decoloration of Astrazon Red FBL solutions. Microtox bioluminescent test was conducted to measure the toxicity of Astrazon FBL solutions treated with high energetic rays. Toxicity reduction has been achieved at 5, 5 and 7 kGy in the range of 81.2, 86.7 and 56.3 % for air, O2 saturated and H2O2 solutions, respectively. As a result of study, it is found that Astrazon Red FBL dye could be treated by irradiation technology.

Removal of Organic Pollutants with Polylactic Acid-Based Nanofiber Composites.

In the process of using nano-titanium dioxide (TiO2) photocatalytic treatment of organic polluted liquid, the easy aggregation and recycling difficulty of nano-TiO2 particles are important problems that cannot be avoided. Anchoring nano-TiO2 to the substrate not only limits the aggregation of nano-TiO2, but also facilitates the easy removal and reuse of nano-TiO2 after processing. Herein, coaxial electrospun nanofibrous (NFs) made of L-polylactic acid (PLLA) and chitosan (CS) are coated with graphene oxide (GO) and TiO2 for the enhanced oxidation of organic pollutants. The adsorption and photocatalysis experiment results show that, for methyl orange (MO) dye solution, the saturated removal of MO by PLLA/CS, PLLA/CS-GO and PLLA/CS-GO/TiO2 nanofibers are 60.09 mg/g, 78.25 mg/g and 153.22 mg/g, respectively; for the Congo red (CR) dye solution, the saturated removal of CR by PLLA/CS, PLLA/CS-GO and PLLA/CS-GO/TiO2 nanofiber materials were 138.01 mg/g, 150.22 mg/g and 795.44 mg/g, respectively. These three composite nanofiber membrane materials can maintain more than 80% of their adsorption capacity after four repeated cycles. They are environmentally friendly and efficient organic pollution remediation materials with promising application.

Synthesis of Green Metaloxide Nanoparticles using Aloe-Barbadensis Leaf Extract (Acid Red 28) for Dye Removal Applications

The present study focuses on the synthesis of stable metal oxide nanoparticles (MO-NPs) using Aloe Vera Barbadensis leaf extracts via a green route approach. The MO-NPs were synthesized by the interaction of Aloe-Barbadensis leaf extract with metaloxide salt and its azodye (Congo red). These NPs were then characterized using SEM (surface morphology), XRD (Crystallography structure, peaks of MO-NPs), UV-Vis (Absorption spectrum) and FTIR (presence of functional group). The SEM images revealed the surface morphology of nano sized powder while the XRD results showed that the particle size ranged between 5-30 nm. The UV-Vis absorption spectrum revealed that the MO-NPs are iron and copper oxide respectively. FTIR data, on the other hand, indicated the hydroxyl (OH) functional group stretching due to the presence of alcohols and phenolic chemicals in the extract. Moreover, the effect of physical properties such as solution concentration, their PH and MO-NPs adsorbent dosage on percentage of dye degradation was also determined. As per results, the NPs removed about 70-80% of Congo red dye solution at optimum condition of reaction factors. The dynamics of pseudo-second order was followed in the adsorption process by MO-NPs.

Exploration of cassava plant xylem for water treatment: preparation, characterization and filtration capability.

Flood is among the natural disasters that commonly happened in Malaysia every year. During the flood, victims faced clean water shortages and deterioration of the environment resulting in long waiting times for aid to access. Hence, affordable and efficient filters are needed to supply clean water in the affected areas. Application of xylem tissue inside plant stem has the potential as a filter for water filtration. This research focuses on xylem tissue in Malaysian tropical plants from cassava stem. Cassava stems were prepared in a small-scale set-up as the xylem was used as a filter. Effects of cross-sectional area and hydrostatic pressure were analyzed and the results showed a directly proportional relationship with permeate flow rate. Upon filtration with red dye solution, total dye removal was achieved using a xylem with a minimal length of 3 cm and onwards. While for bacteria removal, E. coli bacteria have been removed when tested with a bacteria count plate. Thus, this study demonstrated the potential of the xylem tissue of the cassava plant as affordable and available natural raw materials to be used as water filters during an emergency.

Separation of dye from aqueous solution by a new gravity compression and aeration system

ABSTRACT Filtration is one of the important technologies for separating suspended particles. Under the condition of gravity compression, the filtration density can be increased and the separation effect of suspended particles can be improved. Considering the complex composition and the difficulty in degrading dye in industrial wastewater, a gravity compression aeration system with a modified polyester fibre ball (denoted as MPFB) was evaluated for the separation of dye from water. Congo red azo dye solution (0–40 mg/L) was selected as the model treatment compound. The MPFB was prepared by adjusting the concentrations of alkali (Quality score 0–25%), β-cyclodextrin (0∼80 g/L), reaction temperature (40–90°C), and silane coupler concentration (Concentration fractions 0–0.8%). We used Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to characterise the MPFB. The separation was affected significantly by adsorption conditions such as MPFB dose and pH. The lower the MPFB dose, the higher the expected adsorption capacity. For the treatment of a dye solution at 500 mg/L, 100% removal was achieved with 48 g/L MPFB, at pH 8 during adsorption under non-circulation aeration. For 24 h of reaction, the system could reach the maximum adsorption capacity of 11.2 mg/g, which followed the pseudo-first order kinetics model and the intraparticle diffusion model. We discovered that circulation aeration provided the best adsorption and electrostatic and hydrogen bonding were the dominant components of adsorption. Overall, the system is a promising technology and has the potential to treat large volumes of dye wastewater.

Reducing the Purification Period of Congo Red Dye Solution By Using Co-Exposure to Ultraviolet and Green Laser as A Photocatalysit Source

Attempts were made over the years to achieve economic and easy methods for water purification. This could well save time, cost, and earn a good process quality for many countries. This study aims to enhance the purification process parameters for Congo red dye polluted water and introduce a developed methodology with an impact on many associated parameters such as the time for water purification process. The research proposes a method to achieve this time reduction by mixing gold nanoparticle (AuNPs) (prepared by chemical reduction method) with Titanium dioxide nanoparticles (TiO2NPs) (prepared by sol-gel techniques). The resulting mixture is incorporated into PVA host to synthesize a hard disk used as a purification disk to treat the pollutant water. The pollutant solution was exposed to different light sources to complete the photocatalyst process. In this respect, sunlight, UV ligh, green laser, blue laser, and combined UV light and green laser were used as a photocatalysis sources. Experimental work was conducted to adjust the right mixture and the right combination of light sources. Results were recorded accordingly and showed a significant reduction in the purification time with less than half the standard period when the conventional purification process is used.

Performance Characterization of 450 nm Visible Light Based Photoacoustic Imaging for Phantom Imaging of Synthetic Dye Contrast Agents

<p class="AbstractText">Performance characterization of 450 nm visible light photoacoustic imaging has been carried out through phantom imaging of methylene blue (MB), methyl orange (MO), and methyl red (MR) dye solutions. The phantom was made of a nylon tube with a diameter of 5.0 mm (outside) and 4.6 mm (inside) having a height of 2.0 mm along with a 6×6 cm black galvanized aluminum plate as the background medium. The nylon tube was filled with each type of solution with varying molecular concentrations of 10, 25, 50 and 100 ppm. Twelve (12) phantom objects were imaged in an area of 10×10 cm. The visible absorption peak known from UV-Visible spectroscopy for each type of solution is at 664 nm (methylene blue), 465 nm (methyl orange), and 522 nm (methyl red). It was also known that the amplitude of PA emissions would increase proportionally to the concentration of dye molecules. Overall, methyl orange solutions had the highest photoacoustic emission amplitude distribution. The analysis showed that the ratio of inner diameter (ID) and wall thickness (WT) between the MB and MO phantom images to the original object were 1:0.83 and 1:0.74 (ID) and 1:3 and 1:1.5 (WT), respectively. On the other hand, the ratio of the outer diameter (OD) of the MR phantom image to the original object is 1:1.28. </p>

3D printed nanofiltration composite membranes with reduced concentration polarisation

3D printed nanofiltration (NF) composite membranes with surface patterns minimising the impact of concentration polarisation (CP) are presented here for the first time. The membranes consist of a NF polydopamine‐coated polyvinylidene fluoride (PVDF/PDA) selective layer on a 3D printed asymmetric wavy (patterned) support. The result is a wavy composite membrane with pure water permeance of 14 ± 2 LMH bar − 1 and molecular weight cut-off of ∼550 Da, measured using a crossflow NF setup at a transmembrane pressure of 2 bar for Reynold number ( Re ) of 700, using a range of dyes (mass balance >97% for all tests). The CP behaviour of the composite membranes was assessed by filtration of Congo red (CR) dye solution (0.01 g L − 1 ) , showing that the wavy pattern significantly reduced the impact of CP compared to the flat membranes, with a nearly tripling of the mass transfer coefficient and a 57% decline of the CP factor. Computational fluid dynamics showed that these significant performance improvements were due to improved hydrodynamics, with the maximum surface shear stress induced by the wavy structure (1.35 Pa) an order of magnitude higher than that of the flat membranes (0.18 Pa) at Re = 700. These results demonstrate that 3D printing is a viable technology route to reducing concentration polarisation in membrane nanofiltration applications. • Fabrication via 3D printing of NF composite membranes with surface wavy patterns. • Wavy composite membranes had a PWP of 14 ± 2 LMH bar − 1 and a MWCO of ∼550 Da. • Concentration polarisation was assessed by filtration of a Congo red solution. • The wavy structure led to a 57% lower CP and triple mass transfer coefficient. • Shear stress over the wavy structure is an order of magnitude higher than the flat one.

Synthesis, characterization, adsorption study, quantum mechanics, monte carlo and molecular dynamics of lead based polymeric compound towards mopping of aqueous methyl red dye

Dyes present acute problems to the environment as they are considered toxic and carcinogenic. Numerous industries such as paper and pulp, textiles, plastics, leather cosmetics and food industries use dyes. Dyes have complex aromatic molecular structures, making them more stable and difficult to biodegrade. As a result, it is critical to investigate quick and effective methods for removing dyes from the environment.The polymeric compound [Pb4(Ben)2(H2O)] was synthesized by refluxing a mixture of benzoic acid and lead acetate trihyrate. The polymeric compound [Pb4(Ben)2(H2O)] was characterized by elemental analysis, melting point determination, thermogravimetric analysis, FT-IR spectrometer, UV–Visible spectroscopy and X-ray crystallography analysis. The characterization results clearly revealed the coordination of lead (II) to the benzoic acid. Activated polymeric compound [Pb4(Ben)2(H2O)] was used to adsorb methyl red. The experimental condition revealed that 118.89 mg of the methyl red dye was adsorbed per gram of the [Pb4(Ben)2(H2O)] polymeric compound at pH 2.0, 20 ppm dye concentration and 90 min of contact time. Kinetics and isotherm studies suggested that the adsorption process was controlled by both physio-sorption and chemo-sorption. The FT-IR spectroscopy and Powder X-ray diffraction of [Pb4(Ben)2(H2O)] polymeric compound before and after the adsorption of methyl red dye both clearly confirmed adsorption. The polymeric compound [Pb4(Ben)2(H2O)] showed high regeneration capacity. After adsorption, AAS analysis of the aqueous solution of methyl red dye revealed that the lead ion concentration was lower than the WHO recommended lead intake. The adsorption of the compound onto methyl red dye surface was explained by quantum mechanics calculations as a donor–acceptor reaction.Monte Carlo simulation and molecular dynamics revealed that the mechanism of adsorption of methyl red on MSMP [Pb4(Ben)2(H2O)] surface is via the covalent, π- π, electrostatic and van der Waals interactions. As a result, [Pb4(Ben)2(H2O)] polymeric compound is a potential adsorbent for methyl red dye.

Efficiency assessment of Cu and Al electrodes in the removal of anthraquinone based disperse dye aqueous solution in electrocoagulation–an analytical approach

ABSTRACT Anthraquinone dyes are tough to degrade compared to azo dyes, due to the resonance in the anthracene structure that leads to more difficulty in the removal and challenges the possibility of an effective decolouration/degradation process. The purpose of this study was to examine the effect of copper and aluminium electrodes in electrocoagulation process for the elimination of an anthraquinone based aqueous solution of Red BFL dye. The efficiency of the electrodes in the dye removal was studied using X-Ray Photoelectron Spectroscopy of the collected sludge, in terms of the respective M(OH)n formation which contributes in coagulation of the dispersed dye molecules and the results indicated that Al formed four types of hydroxides and Cu only one type. The maximum removal of the dye solution obtained with Al was 99.17% at the optimum conditions: pH 8, contact time 15 min, current density 40 A m−2, and 91.88% with Cu: pH 9, contact time 25 min and current density 60 A m−2. Phytotoxicity and ecotoxicity studies with Vigna radiata and Artemia salina was done to investigate the toxicity of intermediate products in the treated Red BFL dye solution, results showed that the Al used Red BFL dye solution was less toxic in comparison to copper. Abbreviation: EC: Electrocoagulation; AQ: Anthraquinone; CD: Current density; CT: Contact time; ECE%: Efficiency in Colour Elimination percentage; HPLC: High-performance liquid chromatography; XPS: X-ray photoelectron spectroscopy; V. radiata: Vigna radiata; A. salina: Artemia salina

Synthesis of Nanocomposite and Study Degradation of Phenol Red Dye

This study aims to investigate the capability of semiconductors such as titanium dioxide, copper oxide and zinc oxide used to remove a hazardous Phenol Red organic dye texture from an aqueous solution. In this sheet, (ZnO), (CuO) and (TiO2) nanoparticles were synthesised utilise a simple chemical process. Nanocomposite has been synthesised by physical process. The purpose of the research was to investigate semiconductors’ capability, such as titanium dioxide, copper oxide, and zinc oxide, to take off a hazardous Phenol Red, a texture dye from an aqueous solution. These nanoparticles and composites’ structural properties described using (XRD) and Field Emission Scanning Electron Microscope (FE-SEM). This paper describes photocatalytic degradation of Phenol Red dye solution using composite CuO/ZnO /TiO2 nanocomposite photocatalysts, in the form of CuO/ ZnO/TiO2 composite as a paint on the Stainless Steel cell, under ultraviolet (UV) irradiations. The effect of factors affecting the reaction, such as the dye’s primary concentration, the effect of temperature, and the value of the acidic function, were studied. The experiential results show that the CuO/ ZnO/TiO2 composite can remove the Phenol Red from wastewater by X-ray diffraction (XRD) and an average volume of copper oxide molecules. The formula of Debar Shearer found that it is equal to 21.33 nm. For zinc oxide, the particle size constructed to be 18.13 nm and titanium oxide was found to be 42.63, and the particle size of the Nano chemical mixture was 20.48 nm. And CuO/ZnO /TiO2 Nanocomposite 20.48, respectively.

MO066CONGO RED DOT TEST AS A DIAGNOSTIC TOOL FOR RENAL AMYLOIDOSIS IN PATIENTS WITH NEPHROTIC SYNDROME

Abstract Background and Aims Amyloidosis is a serious mostly systemic disease caused by the deposition of abnormal proteins with a cross-β-sheet conformation in tissues and predominantly affecting kidneys among other organs that are associated with inferior renal outcome. Nephrotic syndrome is a common clinical manifestation of renal amyloidosis (RA) among other primary glomerulopathies. Nowadays there is a lack of non-invasive diagnostic tools for screening RA. The aim of this pilot study was to investigate the Congo Red Dot (CRD) test supplemented with polarizing microscopy as a non-invasive technique for detecting RA in patients with nephrotic syndrome. Method In this cross-sectional study, we enrolled patients with nephrotic syndrome (NS, n = 41, aged 52±12 years, 48.8% of males) and healthy individuals without proteinuria for control group (CG, n = 32, aged 45±18 years, 45.5% of males). The first-morning urine samples from all included persons were used for the CRD test. In all cases the protein-creatinine ratio (PCR) was assessed at 24-hour urine collection as well as estimated glomerular filtration rate (eGFR) using CKD-EPI formula. Kidney biopsy was carried out for morphological verification of diagnosis in all patients with nephrotic syndrome. For the Congo Red Dot test, 4 µl of Congo red dye solution (CR) was mixed with 2 µl of a sample of the patient's first-morning urine sample. This mixture was applied in duplicates onto a nitrocellulose membrane (0.45 µm). To quantify the Congo Red Retention (CRR, %), which means the staining intensity the membrane was washed in ascending series of ethanol concentrations and photographed under constant conditions before and after washing in the specially designed photo camera. The CRR was determined as the ratio of the average brightness for two spots on the membrane after and before washing in ethanol and calculated using the ImageJ software. For polarizing microscopy urine samples were centrifuged at 1500 g for 15 minutes at +4°C, the supernatant was removed, 5 µl of CR was added to the sediment and 10 µl was applied to a histological slide, and viewed under polarized light. Data are presented as median and interquartile range (M (25%; 75%)). To assess the significance of differences between groups, the nonparametric Mann-Whitney test was used. Spearman's correlation analysis was used to investigate the relationships between the variables. Receiving operating characteristic (ROC) curve was generated to assess the utility of CRR in prediction of RA. Results The CRR in the NS group (42.2% (26.8; 74.2)) significantly differs from the CRR in the CG group (0.0%), p<0.001. PCR in the NS group was 4.8 g/g (2.2; 11.2). The examples of CRD test results are shown in Figure 1a. By morphological diagnosis, patients were divided into two groups: renal amyloidosis (RA, n = 16, aged 58.3±7.5 years, 50% of males) and non-amyloid variant of nephropathy (NN, n = 25, aged 48.6±12.1 years, 48% of males). There was no significant difference between CRR in RA (71.6% (15.0; 91.8)) and NN (41.7% (27.5; 70.4), p=0.41 as well as between PCR (6.5 g/g (1.4; 15.4) in RA and 3.6 g/g (1.9; 10.4) in NN, p=0.34). Correlation between CRR and PCR in the NN (r=0.722, p<0.0001) and RA (r=0.605, p=0.013) was determined. ROC-analysis showed that threshold value for the diagnosis of RA can be taken as CRR=33.5% with sensitivity 68.8% and specificity 68.4% (Figure 1b). Despite the absence of differences in the CRR, polarization microscopy showed specific apple-green birefringence of aggregates bound with CR in the sample of patient with AL-amyloidosis (Figure 2 a, b) contrary to the sample of patient with IgA-nephropathy (Figure 2 c, d). Conclusion Preliminary results suggest that CRD test supplemented with polarizing microscopy could be used for RA screening in patients with nephrotic syndrome but require further validation as far as congophilia of urine samples from patients with non-amyloid nephropathy also presents.

Analysis of the tautomeric equilibrium of two red monoazo dyes by UV–Visible, Raman and SERS spectroscopies

Acid Red 26 and Acid Red 18 are two early synthetic dyes belonging to the monazo dye class. The molecular structure of this class of dyes is characterized by the chromophoric azo group (NN) generally attached to benzene or naphthalene derivatives containing electron withdrawing and/or donating groups as substituents. As both red dyes have an OH group in ortho- position respect to the azo group, they undergo an azo-hydrazone tautomerism. In this work, UV–Vis, Raman and SERS spectroscopic analysis of the red dye solutions were carried out at different pH conditions, in order to evaluate the preponderance of one tautomer over the other as a function of the pH. Different experimental conditions were tested in order to find the best ones for the detection of both dyes. Thus, Raman spectra of the powder and aqueous solutions of AR26 and AR18 were obtained at the natural pH of the solutions, and above and below that value. The SERS analysis of the dye solutions were carried out at various pH values between 2 and 10, and with excitation at 442, 532 and 633 nm. The molecular structure and the theoretical Raman spectra of the two tautomers of both red dyes were calculated by DFT methods. The obtained results were used for the assignment of the Acid Red 26 and Acid Red 18 vibrational modes. Finally, a textile sample dyed with AR18 was analyzed by SERS.