Spectrophotometric Measurements Research Articles

Measuring Protons with Photons: A Hand-Held, Spectrophotometric pH Analyzer for Ocean Acidification Research, Community Science and Education.

Ocean Acidification (OA) is negatively affecting the physiological processes of marine organisms, altering biogeochemical cycles, and changing chemical equilibria throughout the world’s oceans. It is difficult to measure pH broadly, in large part because accurate pH measurement technology is expensive, bulky, and requires technical training. Here, we present the development and evaluation of a hand-held, affordable, field-durable, and easy-to-use pH instrument, named the pHyter, which is controlled through a smartphone app. We determine the accuracy of pH measurements using the pHyter by comparison with benchtop spectrophotometric seawater pH measurements, measurement of a certified pH standard, and comparison with a proven in situ instrument, the iSAMI-pH. These results show a pHyter pH measurement accuracy of ±0.046 pH or better, which is on par with interlaboratory seawater pH measurement comparison experiments. We also demonstrate the pHyter’s ability to conduct both temporal and spatial studies of coastal ecosystems by presenting data from a coral reef and a bay, in which the pHyter was used from a kayak. These studies showcase the instrument’s portability, applicability, and potential to be used for community science, STEM education, and outreach, with the goal of empowering people around the world to measure pH in their own backyards.

Studies of ninhydrin and phenylalanine in cationic dimeric gemini micellar system: Spectrophotometric and conductometric measurements

Present work deals with studies of ninhydrin (N) and phenylalanine (Phe) in cationic gemini micellar system by spectrophotometer under diverge kinetic environments. The results of the current study follow fractional-order in N and first-order in Phe. The study is intensely catalyzed by gemini surfactant (GS) system and rate constants (kψ) are enriched even though at [GS] lower than critical micelle concentration (cmc). The noticed enhancement in rates between reactant molecules and gemini is attributed to hydrophobic and electrostatic interactions. To interpret the influence of various [GS], ranging from (1–3000) x 10−5 mol dm−3, on kψ, a model so-called pseudo-phase originally proposed by Berezin et al. and improved by Bunton was applied. Various parameters and constants (like binding constants, thermodynamic parameters and micellar rate constants) have been evaluated. Under the present kinetic condition, a probable reaction mechanism between N and Phe is recommended. The conductivities of pure gemini and the presence of reactants at two temperatures, i.e., at 303 K and 343 K were measured using a conductivity instrument. The cmc of pure geminis in the current case determined at 303 K is consistent with those data reported, earlier.

Evaluation of the influence of thermal annealing on the performance of vertical topological insulator p-n heterojunction broadband photodetector

The rapid progress and continuum search for new broadband photodetectors generation with ultrafast response synchronizes with the conductive surface electronic structure and the strong broadband absorption properties of 3D topological insulators. Here, we introduce the fabrication of a vertical p-n heterojunction based on thermally evaporated thin films of Sb2Te3/Bi2Te3 on Si substrate for broadband photodetection. The realization of these characteristics dictated us to study the structural, optical absorption, and morphological properties of each layer in the fabricated device as a function of annealing temperature using XRD, spectrophotometric measurements, and FE-SEM techniques, respectively. The annealing process up to T = 423 K enhanced the film’s crystallinity, and grain growth process besides improving the film quality and surface roughness. Furthermore, the optoelectronic characterizations showed that all fabricated photodetectors exhibit a good response to halogen light illumination in the wavelength range (310–1100) nm with different intensities (10–50) mW/cm2. Whilst the 423 K annealed photodetector showed the highest photosensitivity with a conspicuous stable and fast response. The main device parameters, including spectral responsivity, specific detectivity, and response times were determined in addition to explaining the forward and reverse bias conduction mechanisms. The estimated spectral responsivity of the fabricated devices was about 0.247, 0.397, and 0.148 A/W for the as fabricated and 423 K and 573 K, respectively. This significant improvement of the device’s performance rather than other topological insulator devices may be due to the strong built-in field at the topological insulators’ interfaces. Moreover, the fabricated photodetectors showed improved and repeatable ON/OFF transient switching behavior with 85.23 ms and 84.66 ms as a rise and fall time, respectively. According to the prominent results in addition to the simple architecture of the fabricated photodetectors, this topological insulator photosensor can be considered a potential candidate in prospective high-performance optoelectronics.

Wood discoloration patterns depending on the light source

The wood photodegradation, including discolouration caused by exposure to UV and solar radiation, has been intensively studied, while the effect of artificial lighting on wood has been little investigated. In the present study, the effect of three types of artificial light sources (LED, incandescent, and fluorescent lamps) on the colour changes of wood was evaluated. LEDs with high (6500 K) and low (3000 K) correlated colour temperature were employed in the experiments. Wood colour was assessed by spectrophotometric measurements of reflectance spectra, which were converted into colour parameters of the CIELAB colour system. The total discolouration as well as the changes in colour lightness, chroma (saturation), and hue were evaluated for two hardwood species (birch, oak) and two softwood species (spruce, pine - sapwood and heartwood) depending on the irradiation dose. Visually perceivable changes in colour of all woods were observed already at relatively low irradiation doses, indicating a high sensitivity of the wood to radiation emitted by artificial light sources. Comparing the softwoods and hardwoods included in the study, the latter proved to be more resistant to discolouration caused by the tested light sources. Overall, greater colour changes in long-term exposure were caused by incandescent and fluorescent lamps, although more rapid discolouration developed in the early stage irradiation with LEDs. A substantial difference between the effect of the tested LEDs was only observed in the initial phase, when the cool LED (6500 K) caused more discolouration. The changes in the colour parameters were complex and varying in directions, including a reversal with the accumulation of the irradiation dose, indicating that the exposure to artificial light sources resulted in continuous alteration in the shade of the wood colour.

Influence of Er and Yb on photoelectrochemical performance of TiO2 thin film

The strategy of modifying the titanium dioxide photoanode with an internal upconverter containing Er activator and Yb sensitizer was proposed. To assess the impact of rare earth ions, thin film TiO2, TiO2:Er, and TiO2:Er,Yb were deposited in the magnetron sputtering process on conducting glass, amorphous silica a-SiO2, and silicon. Two strategies were tested: introduction of high activator content and incorporation of low activator content with addition of sensitizer. Pure TiO2 served as a reference material. All deposited films displayed promising optical properties, such as high transparency and low reflectance in weak absorption region, and strong absorption above the fundamental absorption edge, as investigated by spectrophotometric measurements. Structural characterization by means of grazing incidence X-ray diffraction and transmission electron microscopy revealed that films crystallized as a mixture of anatase and rutile, while high concentration of modifying ions led to amorphization. Changes in surface morphology accompanied the structural transition, as shown in scanning electron microscopy analysis. Current-voltage and time-dependent measurements in photoelectrochemical cells, under white light illumination before and after cut-off of ultraviolet light, confirmed enhanced performance of TiO2:Er,Yb (1 at.%, 1 at.%) photoanodes over pure TiO2 as well as TiO2:Er (10 at.%) and TiO2:Er,Yb (2 at.%, 10 at.%).

The Novel Potentiometric Approach to Antioxidant Capacity Assay Based on the Reaction with Stable Radical 2,2'-diphenyl-1-picrylhydrazyl.

For the first time, new possibilities of using the DPPH• as a signal-forming oxidant molecule with potentiometric detection are shown. The CV method confirmed the presence of a quasi-reversible potential-determining system DPPH•/DPPH-H under experimental conditions. This fact makes it possible to use DPPH• as the model of the oxidizing agent for obtaining an analytical signal by the potentiometry method. The potentiometric approach makes it possible to obtain the value of the Nernst slope and the antioxidant capacity in one experiment. It consists of an antioxidant supplement and two consecutive DPPH• supplements. In this case, the calculation of the Nernst slope is carried out by introducing the second addition of the oxidizing agent and constructing a calibration curve against the reaction background with an antioxidant. Solutions of individual antioxidants α-tocopherol, quercetin, (±)-catechin hydrate, and α-lipoic acid were studied by the developed approach. A high correlation with the results of spectrophotometric measurements is shown. At the same time, the potentiometry method is devoid of the concentration limitations of the spectrophotometric method, which was confirmed. In the study of plant materials extracts, a high correlation of antioxidant capacity, obtained by potentiometric and spectrophotometric methods, was shown only for objects whose color did not contribute to the DPPH• absorption. The versatility of the potentiometric method for studying objects of any color was shown.

The Role of eDNA in Biofilm Structure of Enterococcus faecalis and Investigation of the Efficiency of Enzyme and Antibiotic Application in Biofilm Eradication

Biofilm structures, which are the predominant form of microbial life, are a formation that allows pathogenic microorganisms to remain alive by colonizing in different tissues and organs in the human body, as well as on inanimate surfaces. One of the important criteria in the fight against biofilm structures is the weakening of the exopolymeric matrix (EPS). Although it is known that extracellular DNA (eDNA) is one of the most abundant macromolecules in EPS in enterococcal biofilms, its function in biofilm structure is controversial. Since biofilm-forming enterococci are more resistant to antibiotics, the use of antibiotics together with agents that will damage the biofilm structure is being investigated. In this study, it was aimed to target eDNA with enzyme application for the eradication of Enterococcus faecalis biofilm structures and to investigate the increase of the effectiveness of antibiotic therapy on it. The amount of eDNA and optimal production time in biofilm structures of four different strains and isolates of E.faecalis (two clinical isolates coded 74 and 114, and two control strains coded ATCC 29212 and ATCC OG1RF) were determined by spectrophotometric measurement of PicoGreen fluorescence. For the eradication of biofilm; the effects of kanamycin, tetracycline, nalidixic acid, and ampicillin alone and in combination with Benzonase® and DNase I enzymes were investigated by viable cell count on Tryptic Soy Agar. It was determined that optimum biofilm production of E.faecalis strains and isolates occurred at 37°C for 12 hours. E.faecalis 114 isolate was identified as the strongest biofilm producer among the tested bacteria and the isolate containing the highest amount of eDNA (286 98 ng/µl) in the biofilm structure. While the tested antibiotics did not show significant antibiofilm activity against E.faecalis biofilm structures alone, strong antibiofilm activity was detected when ampicillin and tetracycline were applied together with DNase I enzyme. In this study, the use of DNA-degrading enzyme/antibiotic combinations in the eradication of enterococcal biofilms and the effectiveness of these combinations against eDNA were investigated for the first time in the literature. As a result, supportive results were obtained that the use of antibiotics together with the DNase I enzyme targeting the DNA molecule in the EPS structure will be more successful in the fight against the biofilm structures of E.faecalis, which is an important cause of nosocomial infection. These results need to be supported by further clinical studies.

The Effect of a Dodecahedron-Shaped Structure on the Properties of an Enzyme

In this research, the influence of a dodecahedron-shaped structure on the adsorption behavior of a horseradish peroxidase (HRP) enzyme glycoprotein onto mica substrates was studied. In the experiments, samples of an aqueous HRP solution were incubated at various distances (0.03 m, 2 m, 5 m, and control at 20 m) from the dodecahedron surface. After the incubation, the direct adsorption of HRP onto mica substrates immersed in the solutions was performed, and the mica-adsorbed HRP particles were visualized via atomic force microscopy (AFM). The effect of the increased HRP aggregation was only observed after the incubation of the enzyme solution at the 2 m distance from the dodecahedron. In addition, with respect to the control sample, spectrophotometric measurements revealed no change in the HRP enzymatic activity after the incubation at any of the distances studied. The results reported herein can be of use in the modeling of the possible influences of various spatial structures on biological objects in the development of biosensors and other electronic equipment.

Electrochemical Biosensing of Glucose Based on the Enzymatic Reduction of Glucose

In this work, the enzyme aldehyde reductase, also known as aldose reductase, was synthesized and cloned from a human gene. Spectrophotometric measurements show that in presence of the nicotinamide adenine dinucleotide phosphate cofactor (NADPH), the aldehyde reductase catalyzed the reduction of glucose to sorbitol. Electrochemical measurements performed on an electrodeposited poly(methylene green)-modified gold electrode showed that in the presence of the enzyme aldehyde reductase, the electrocatalytic oxidation current of NADPH decreased drastically after the addition of glucose. These results demonstrate that aldehyde reductase is an enzyme that allows the construction of an efficient electrochemical glucose biosensor based on glucose reduction.

Computational Insights in the Spectrophotometrically Analyzed Niobium (V)- 3-Hydroxy-2-(4-methylphenyl)-4H-chromen-4-one Complex using DFT Method

Using 3-hydroxy-2-(4-methylphenyl)-4H-chromen-4-one (HMC) as a complexing agent in an acidic medium, a simple, quick, highly sensitive, and selective approach for the extractive spectrophotometric measurement of micro quantities of niobium (V) is developed. The yellowish 1:3 complex can be extracted 100 % in dichloromethane (DCM), attaining maximum absorbance in the wavelength range 388-407 nm. At 400 nm, the selected wavelength, the approach follows a linear calibration curve up to 2.2 g Nb (V) ml-1 and 0.395-1.78 ppm Nb (V) as identified from the Ringbom Plot with molar absorptivity, specific absorptivity, and Sandell's sensitivity of 4.926 × 104 l mol-1 cm-1, 0.5302 ml g-1 cm-1 and 0.0019 µg Nb cm-2, respectively. With a correlation coefficient of 0.9994, the linear regression equation is Y = 0.514 X + 0.016. The method's detection limit is 0.0698 µg ml-1. The presented determination of pentavalent niobium is unaffected by 33 cations and 22 anions/complexing agents. The approach has good reproducibility and can be used to determine niobium in a satisfactory manner. The analytical study has been correlated well with the theoretical approach of Density Functional Theory (DFT) for quantum chemical calculations. DFT effectively helped determine and interpret the chemical behavior of the obtained Nb(V)-HMC complex, explaining its stability and reactivity pattern.

Physicochemical Study, Fatty Acid Profile and Antioxidant Potential of the Seed Oil of Polyalthia longifolia angustifolia

In the face of worsening malnutrition or undernutrition in poor countries, diversification of food resources remains a high priority for the World Health Organization (WHO). Thus, the present study aims to determine the phytochemical composition and antioxidant activity of the fat extracted from the seeds of Polyalthia longifolia angustifolia.
 The fatty acid profile of the oil, extracted from the seeds with hexane by the Soxhlet method, was determined by gas chromatography-mass spectrometry (GC/MS) analysis. The physicochemical parameters of the oil were measured according to AFNOR standards. The total phenol and flavonoid contents of the seeds were evaluated by UV-visible spectrophotometric measurement. Antioxidant activity of the oil was determined by the reduction test of ferric ions (Fe3+) of the TPTZ complex to ferrous ion (Fe2+). The results revealed that the oil contains a higher level of oleic acid (63.38%), followed by: palmitic acid (13.80%); linoleic acid (11.74%) and stearic acid (6.24%). The physicochemical parameters of the oil were: refractive index (1.499); acid value (87.69 mg KOH/g of oil); acidity (23.659 g oleic acid/100 g of oil); iodine value (78.26 g I2/100 g of oil); saponification value (179.741 mg KOH/g of oil) and peroxide number (10.85 meq O2 /kg of oil).
 In short, the seeds of P. l. angustifolia contain fat and phytochemicals with appreciable antioxidant activity. However, further studies are needed to evaluate the toxicity, nutritional and therapeutic properties of the oil before considering the different types of applications that can be made with this oil.

Electrodeposited Fe on Cu foam as advanced fenton reagent for catalytic mineralization of methyl orange.

In many countries, the textile industry remains the major contributor to environmental pollution. Untreated textile dyes discharged into water negatively impact the performance of aquatic organisms and may cause a variety of serious problems to their predators. Effective wastewater treatment is a key to reducing environmental and human health risks. In this work, the Fe/Cu catalysts were used in heterogeneous Fenton’s reaction for the degradation of high concentrations of methyl orange (model azo dye) in aqueous solutions. For the first time, the catalysts were prepared onto commercial copper foams by potentiostatic electrodeposition of iron using an environmentally friendly electrolyte. The influence of electrodeposition conditions, H2O2 concentration, dye concentration and temperature on the model dye degradation was investigated. It was revealed that both the surface area and the catalyst loading play the major role in the effective dye degradation. The experimental results involving spectrophotometric measurements coupled with total carbon and nitrogen quantification suggest that a solution containing up to 100 mg/L of methyl orange can be successfully decolorized within 90 s at 50°C using porous Fe/Cu catalyst in the presence of hydrogen peroxide that largely surpasses the current state-of-the-art performance. Already within the first 10°min, ∼ 30% of total methyl orange concentration is fully mineralized. The described process represents a cost-efficient and environmentally friendly way to treat azo dyes in aqueous solutions.

12- months color stability of direct resin composite veneers in anterior teeth: Clinical trial

Background: This clinical trial aims to evaluate the color changes of direct resin composite veneer (DCV) restorations based on spectrophotometric analysis of 4 different types of resin composites between the baseline immediately after polishing and after one year of follow-up. Materials and methods: 28 patients were assessed for eligibility for participation, aged between 18 and 38 years old, who indicated for DCV restorations in anterior maxillary teeth were considered for participation in this study. In total, 25 patients who met the inclusion criteria were selected (6 males and 19 females, mean age: 20.9 at the time of restoration placement), and 3 patients were excluded. Participants were divided into four groups based on the type of composite resin used for restorations. Group 1 nanohybrid Ips Empress direct (Ivoclar Vivadent)](IPS) (13 restorations/6 patients), group 2 microfilled [Essentia (GC cooperation Japan)](ES) (14 restorations / 7 patients), group 3 supra-nano filled [ Estelite ∑ Quick (Tokuyama, Tokyo, Japan)](EQ) (17 restorations / 7 patients) and group 4 nanofill [Filtek Ultimate (3M ESPE)](FU) (13 restorations / 5 patients). Baseline Color measurements were performed with a spectrophotometer immediately after finishing and polishing (baseline), and after one year of recall, color change (ΔE) from baseline values and after one year of follow-up of DCVs were calculated according to CIELab color coordinates. For this, a silicone mold was fabricated for each patient and used as a guide for each measurement to standardize the site of the readings. Statistical analysis of the data was applied using the Kruskal-Wallis test with Dunn-Bonferroni posthoc test after controlling the distribution of data in terms of normality with the Shapiro Wilk test. Results: At the end of one year,25 participants(57restorations) were followed up. The mean ΔE of IPS, EQ, and FU composites were higher than the ES composite resin, but there was no statically significant difference between all types of composites (P> 0.05). There was no statistically significant difference in the mean ΔL* between any types of composite resin (p> 0.05). There was a significant change in Δa* and Δb* after a one-year recall for all the types of DCV restorations (p < 0.05). Conclusion: After one year of follow-up, the spectrophotometer measurements of direct resin composite veneer restorations, it was concluded no difference between the mean ΔE of ES, IPS, FU, and EQ resin composite. ES (Microfilled hybrid) showed a lower mean ΔE value compared to the other groups. All groups of resin composite showed color changes within clinically acceptable levels after a one-year follow-up.

Biosynthesis of ZnO photocatalyst and its application in photo catalytic degradation of methylene blue dyestuff

In this research, biosynthesis of zinc oxide nanoparticles (ZnO-NPs) was performed using aqueous extract of the leaves of Cynara scolymus L (CsL, artichoke) plant. The synthesized CsLZnO-NPs were characterized by Ultraviolet-visible (UV-Vis) absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD) and Energy dispersive x-ray spectroscopy (EDS). Production of CsLZnO-NPs was approved by surface plasmon resonance (SPR) peak localized at 366 nm and the band seen at 417 cm−1 (Zn-O stretching) in the FTIR spectrum. EDS spectrum also confirmed formation of CsLZnO-NPs. The percentage composition by mass of the synthesized CsLZnO-NPs is close to the theoretical mass percentage composition (Zn: 80%, O: 20%) of the ZnO molecule. TEM analysis showed that the particles are of sub-micron size and have no sharp boundaries or morphologies. CsLZnO-NPs with wurtzite structure were characterized by XRD analysis. The average size of CsLZnO-NPs was measured to be 332.5 nm. The band gap energy value of CsLZnO-NPs was found to be 2.9 eV which is lower than the band gap of bulk ZnO (3.37 eV). Produced CsLZnO-NPs were utilized as a photocatalyst for decolorization of Methylene Blue (MB) dyestuff. Under UV-light, 80% decolorization efficiency was achieved in 240 min. In the present study, correct results were obtained by taking first derivative spectra in the presence of turbidity in centrifuged and filtered samples or in samples with high background absorbance in the spectrophotometric measurements of photocatalysis reactions. Decolorization of MB dyestuff follows the pseudo-first order kinetic.

A Simple and Cost-Effective Protocol for DNA Isolation from Herbarium Specimens

We developed a new CTAB-based seven-step DNA extraction protocol to isolate DNA from herbarium specimens. DNA was extracted from five species belonging to five genera from four families of angiosperms. The spectrophotometric measurement of double-stranded DNA demonstrated DNA of sufficient quality and quantity for PCR analysis. DNA was tested with universal primers and amplification success was 95%. The protocol is applicable to different taxonomic groups of herbarium specimens, fresh and silica-dried samples, and requires only common laboratory consumables and equipment. It is possible to extract 30 samples in less than two hours and more than 120 samples in a working day. The cost of consumables per sample is less than in many traditional protocols and commercially available kits.

The effects of whitening mouthrinses on the color stability of CAD/CAM resin matrix ceramics

Objective: This study aimed to evaluate the color change of CAD/CAM resin matrix ceramic, which was exposed to three different whitening mouth rinses and artificial saliva for 12 and 180 hours. Material and Methods: A total of 60 samples were produced from prefabricated CAD/CAM resin matrix ceramic blocks for experimental study. The samples were randomly divided into four subgroups according to the whitening mouthrinses: Listerine Advanced White, Colgate Optic White, Oral B 3D White Luxe, and artificial saliva. Spectrophotometric measurements were made from each sample at 3 different times, before (initial) exposure to mouthrinses, 12 hours and 180 hours after exposure (∆E001, ∆E002 and ∆E003). While using the generalized linear models method for the comparison of ∆E00, ∆L, ∆a, and ∆b color changes according to the mouthrinse and exposure time; multiple comparisons were made with the Tukey HSD Test. The significance level was taken as p<0.050. Results: The results of the two-way analysis of variance showed that the used mouthrinse and the exposure time had a statistically significant effect on the ∆E00 values representing the color change (p<0.001), while the interaction between the mouthrinse and the time of use did not play an important role (p=0.165). Conclusion: After exposure time of 180 hours, all whitening mouthrinses induce color change of resin matrix ceramics above clinically noticeable level.

Active corrosion protection of AA2024 aluminum alloy by sol-gel coating containing inhibitor-loaded mesoporous SBA-15

Santa Barbara Amorphous-15 (SBA-15) silica were synthesized, and then aminated using 3-aminopropyl triethoxysilane (APTES). Afterward, Diclofenac Sodium (DFS) was loaded into the pores of the aminated SBA-15 before encapsulation in a polyelectrolyte shell. The SBA-15 showed a tubular morphology which did not influence by the amination and DFS loading. Spectrophotometric measurements showed that the release of the diclofenac sodium from the encapsulated substance is a pH-dependent process. The highest amount of the DFS molecules released at pH = 10 after about 2 h. The sol-gel coatings containing the appropriate concentration (1 g L−1) of the aminated and encapsulated SBA-15 were applied on the AA 2024 aluminum alloy. The SEM (scanning electron microscopy) images of the neat sol-gel coating showed structural micrometric cracks. However, the cracks were removed after adding 1 g L−1 of the aminated and encapsulated materials. Uniform distribution of the encapsulated material in the coating was approved by TEM (Transmission electron microscopy). In addition, a relative improvement in the thermal stability of the coating was observed after incorporating the encapsulated nanomaterial. The EIS (Electrochemical Impedance Spectroscopy) studies after 150 day of immersion in the simulated acid rain solution showed that the polarization resistance (Rp) of the sol-gel coating improved from 0.006 to 0.05 MΩ cm2 after incorporating the aminated SBA-15. Also, the polarization resistance was further enhanced to about 14.454 MΩ cm2 by incorporating the same concentration of the encapsulated SBA-15, indicating a significant improvement in the corrosion resistance. The polarization resistance of the coating containing encapsulated SBA-15 increased from 8.664 to 14.454 MΩ cm2 with increasing the immersion time from 120 to 150 days, likely due to intelligent release and subsequent adsorption of the diclofenac sodium on the active corrosion sites.

Spectrophotometric method for the determination of chlordiazepoxide, diazepam and alprazolam drugs by using oxidation coupling reaction

Sensitive, accurate, precise and efficient spectrophotometric"method for the determination of chlordiazepoxide, Diazepam and Alprazolam drug (CH, DIA, ALP) in pure as well as in dosage form was described."The suggested method was based on oxidation coupling reaction of suggested drug (CH, DIA, ALP) drug using acidic buffer "then"coupling with"3-methyl-2-benzothiazolinone hydrazone hydrochloride"(MBTH) in the presence of ferric chloride. Spectrophotometric measurement was established by recording the absorbance of the blue colored product at (663,609,619) nm. Using the optimized reaction conditions, beer’ s law was obeyed in the range of"(2.5-25) µg/mL "(5-30) µg/mL, and "(5-30) µg/mL with good correlation coefficient of (0.9997, 0.9979, 0.9965) and the LOD and LOQ ( CH,DIA,ALP) values were( 0.1750, 5.834 , 0.676 and 2.253 ,0.881and 2.938)μg/mL for chlordiazepoxide, Diazepam and Alprazolam drug respectively. The accuracy and precision of the proposed method represented by recovery and relative standard deviation were satisfactory; about 99.33% and)") 0.502and 0.195, 0.46) μg/mL for chlordiazepoxide, Diazepam and Alprazolam drug respectively. The "proposed"method"was"applied"for"determination"of (CH, DIA, ALP) in"its"pharmaceutical" "forms"and"the"results"compared successfully"with"the"obtained"by"standard"method (British"pharmacopeia"method).

Periodontal status is associated with oral function in community‐dwelling older adults, independent of dentition status

To determine whether periodontal status is associated with oral function, including masticatory performance and occlusal force, among community-dwelling older adults. Although a potential association between periodontal status and oral function has been reported, variations in the root surface area (RSA) of each tooth have not been considered. We used data from a population-based study involving community-dwelling older adults. The RSA with periodontal ligament (RSA-PL), which quantifies the RSA attached to the periodontal ligament and alveolar bone, was calculated based on full-mouth periodontal examination. Masticatory performance was assessed using spectrophotometric measurement of the color (a* value) of color-changing chewing gum. The bilateral maximal occlusal force (MOF) was measured using a pressure-sensitive sheet and dedicated software. The associations of the RSA-PL, a quantitative marker of periodontal tissue support, with the a* value and MOF were assessed using linear regression models. The analyses included data from 250 adults [60.8% women; age, mean (standard deviation) 82.5 (5.0) years]. On average, the study participants had an RSA-PL of 26.3cm2 , a* value of 25.0, and an MOF value of 555.1N. After adjustments for potential confounders, including dentition status, age, sex, dental visit regularity, smoking status, physical activity level, depressive symptoms, a history of stroke or diabetes mellitus, and body mass index, the RSA-PL was found to be associated with the a* value [coefficient (per 1cm2 increase): 0.16, 95% confidence interval (CI) 0.10-0.22)] and MOF (coefficient: 9.2, 95% CI 5.3-13.1). This study demonstrated that greater amounts of remaining tooth-supporting structures, indicated by higher RSA-PL values, were associated with better masticatory performance and a higher occlusal force among community-dwelling older adults.

Protein G: β-galactosidase fusion protein for multi-modal bioanalytical applications.

β-galactosidase (β-gal) is one of the most prevalent markers of gene expression. Its activity can be monitored via optical and fluorescence microscopy, electrochemistry, and many other ways after slight modification using protein engineering. Here, we have constructed a chimeric version that incorporates a streptococcal protein G domain at the N-terminus of β-gal that binds immunoglobins, namely IgG. This protein G: β-galactosidase fusion enables β-gal-based spectrophotometric and electrochemical measurements of IgG. Moreover, our results show linearity over an industrially relevant range. We demonstrate applicability with rapid spectroelectrochemical detection of IgG in several formats including using an electrochemical sensing interface that is rapidly assembled directly onto electrodes for incorporation into biohybrid devices. The fusion protein enables sensitive, linear, and rapid responses, and in our case, makes IgG measurements quite robust and simple, expanding the molecular diagnostics toolkit for biological measurement.