Analyte-restrained silver coating of gold nanostructures: An efficient strategy to advance multicolorimetric probes

2021 ◽  
Author(s):  
Amene Naseri ◽  
Forough Ghasemi
Keyword(s):  
Limit Of Detection ◽  
Direct Detection ◽  
Silver Coating ◽  
Silver Deposition ◽  
Deposition Mechanism ◽  
Sensing Applications ◽  
The Difference ◽  
Dark Blue ◽  
Selection Of

Abstract Visual detection based on gold nanorods (AuNRs) has gained tremendous attention in sensing applications owing to the potential for simple, inexpensive, instrument-free, and on-site detection. The proper selection of the mechanism involved in the interaction between the analyte and the nanostructure plays a significant role in designing a selective and multicolorimetric probe for visual purposes. A winning mechanism to develop multicolorimetric probes is the silver metalization of AuNRs. Herein, an unprecedented idea is presented to expand the variety of multicolorimetric sensors relying on the mechanism of silver deposition. We introduce the anti-silver deposition mechanism in which the analyte directly or indirectly restrains the silver coating of AuNRs. To ascertain the anti-silver deposition mechanism, we have exploited the proposed idea for the direct detection of nitrate. The presence of nitrate (as restrainer agent), which was firstly treated with ascorbic acid (as reducing agent), induced a decrease in the spectral blueshift of AuNRs along with diverse sharp color transitions from reddish-orange (blank) to maroon, wine, berry/purple, dark blue, teal, green, seafoam, and mint. The difference in the surface area of the probe’s spectra in the absent (Sₒ) and presence (S) of nitrate were linearly proportional to nitrate concentration in the range of 0.5 to 5.5 mmol L-1 and the limit of detection (LOD) was calculated to be 465 µmol L-1. Furthermore, the practicability of the multicolor probe was assessed by the determination of nitrate in complex environmental samples.

scholarly journals The Methodological Recommendations for Improving the Management of Enterprise Competitiveness in the Service Sector

2021 ◽  
Vol 9 (524) ◽  
pp. 243-249
Author(s):  
S. M. Osypenko ◽  
◽  
T. V. Romanchyk ◽  
O. M. Tesnikov ◽  
I. O. Kuruch ◽  
...  
Keyword(s):  
Service Sector ◽  
Practical Implementation ◽  
Economic Management ◽  
Managerial Decisions ◽  
The Difference ◽  
The Competitiveness Of Enterprises ◽  
Analysis Determination ◽  
Selection Of ◽  
Integral Indicator

The relevance of the problem of managing the competitiveness of service sector enterprises in modern conditions of economic management is determined. In a contentual form, the task of managing the competitiveness of enterprises is formulated and a scheme of its implementation is proposed, which includes the following stages: formation of factors that determine competitiveness; substantiation of the competitiveness indicator and its model; computing the competitiveness indicator and its subsequent factor analysis; determination of reserves for growth of the competitiveness index; formation of the task of increasing competitiveness; formation of a list of measures for implementing the task; selection of measures for the implementation; implementation of measures, control and regulation. The procedure for computing the integral indicator of competitiveness, which includes groups of indicators that determine the state of the enterprise and the competitiveness of its products, as well as indicators within each group, is considered. The methodology of economic analysis of the level of competitiveness of the enterprise is proposed, which allows to conduct an overall assessment of its competitive position compared to competitors; determine the influence of factors on the difference in their position from the position of competitors; calculate the reserves of growth of the competitiveness indicator and develop measures for their implementation. In accordance with the competitive strategy of the enterprise and the task of increasing the competitiveness indicator on the basis of the use of the provisions of the theory of economic efficiency, a list of measures is substantiated, the practical implementation of which will allow to perform the task with a minimum amount of resources. Operational control over the implementation of measures and their impact on the competitiveness indicator is envisaged in order to make corrective managerial decisions in a timely manner.

MEME: DAPATKAH MENINGKATKAN KEMAMPUAN SISWA DALAM MENULIS TEKS ANEKDOT?

2018 ◽  
Vol 2 (1) ◽  
pp. 105
Author(s):  
Fajar - Gumelar
Keyword(s):  
Project Based Learning ◽  
Student Centered ◽  
Student Centered Learning ◽  
Plan Selection ◽  
Productive Process ◽  
The Difference ◽  
Stage 1 ◽  
And Control ◽  
Selection Of

Writing anecdote text is a creative and productive process, meaning an ability that requires students to produce a product (writing) that aims to provide criticism/ satire accompanied by humor against an event that occurred. The fact that the ability to write anecdot text is still low, the difficulty in putting ideas and ideas into the main factor. The need for a model of learning with the use of media as a way to overcome these problems. Projects based learning assisted media meme are used based on literature review, which is a student-centered learning by applying the concept of the project (based on actual life that occurs) in order to solve the problem independently by using memes as a media that serves to clarify a message or content delivered. At the stage (1) the determination of fundamental questions about the events that occur (actual), (2) preparing the project plan (selection of data collection activities), (3) preparing a schedule (completion of activities), (4) monitoring project progress, (5) assessment of results, and (6) evaluation of experience (reflection of activities). This research aims to determine (a) the effectiveness of the model and (b) the effectiveness of the model in the experimental class (MIPA and IPS). The methodology used is a quasi experiment with 2 by 2 factorial research design. The results of research from data analysis, obtained (a) the difference in ability between the experimental class and control class students with N-gain experiments enter into medium category, while the N-gain controls enter into low category. (b) there is no difference ability in experimental class between MIPA and IPS class students. This shows that the model of Projects based learning assisted media meme effectively used in the class with the background of MIPA and IPS in SMA Negeri 15 Bandung. Keyword: writing anecdote text, project based learning, and media meme. 

scholarly journals Development of a new analytical spectroscopic methodology based on the competitive aggregation in a dye–surfactant–drug system: Application to the determination of gemfibrozil

2008 ◽  
Vol 22 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Mohammad Amjadi ◽  
Jamshid L. Manzoori ◽  
Leila Farzampour
Keyword(s):  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Calibration Graph ◽  
Experimental Conditions ◽  
Analytical Methodology ◽  
Surfactant Aggregates ◽  
Didodecyldimethylammonium Bromide ◽  
The Difference ◽  
Absorption Features

A new analytical methodology based on the competitive aggregation in a dye–surfactant–drug system is developed for the determination of gemfibrozil. Eriochrome Blue Black R (EBBR) and Didodecyldimethylammonium bromide (DDABr) were the dye and surfactant used, respectively. In the proposed method, the anions of the dye bind to the cationic surfactant molecules to form dye–surfactant aggregates, which are monitored from changes in UV-Vis absorption features of the dye. In the ternary EBBR–DDABr–drug mixtures, the drug competes with the dye to interact with the surfactant, which results in a decrease in dye–surfactant aggregates formation. This, again, causes a change in absorption properties of the dye. The measurement parameter is the difference between the absorption of the dye in the presence and absence of the drug. In the appropriate experimental conditions the absorbance differences are directly proportional to the drug concentration. The influence of several experimental variables such as pH, concentrations of buffer, EBBR and DDABr on the measurement parameter were studied. Under the optimum conditions, the calibration graph was linear up to 6.0 μg ml−1with the correlation coefficient of 0.998. The limit of detection and quantification were found to be 0.044 and 0.15 μg ml−1, respectively. The method was validated and applied to the determination of gemfibrozil in pharmaceutical preparations.

scholarly journals Development and Validation for Simultaneous Estimation of Sofosbuvir and Daclatasvir Dihydrochloride in Pharmaceutical Dosage form by Ratio Derivative and Dual Wavelength Methods

2020 ◽  
Vol 11 (01) ◽  
pp. 25-31
Author(s):  
Sapna M. Rathod ◽  
Paresh U. Patel
Keyword(s):  
Dosage Form ◽  
Dual Wavelength ◽  
Simultaneous Estimation ◽  
Pharmaceutical Dosage Form ◽  
First Derivative ◽  
Absorbance Difference ◽  
The Difference ◽  
Development And Validation ◽  
Selection Of

Development and validation of new simple, sensitive, accurate and precise spectrophotometric method involving ratio derivative and dual-wavelength method, was done as per ICH Q2 (R1) for simultaneous estimation of Sofosbuvir (SOFO) and daclatasvir dihydrochloride (DACLA) in a combined dosage form. The overlapping in the spectra of both drugs was the reason for the selection of both methods. The absorbance difference (ΔA) value between 235.8 nm and 270.6 nm was selected for the quantitative determination of SOFO, where DACLA gives equal absorbance at the selected wavelength in the dual-wavelength method (Method A). The determination of DACLA is done quantitatively by measuring the difference in absorbance value at 249 nm and 268.6 nm where SOFO gives equal absorbance at a selected wavelength. Ratio spectra method (Method B) was based on dividing the spectra of a mixture with standard spectra of one of the analytes, and the first derivative spectra was recorded with Δλ = 8 nm and scaling factor 1. The amount of SOFO and DACLA was estimated in the binary mixtures by computing the first derivative signal at 247.0 nm and 341.0 nm, respectively. The calibration curve was linear in the concentration range of 10–90 μg/mL for SOFO and 4–20 μg/mL for DACLA for both the methods. The methods were successfully applied for the simultaneous determination of these drugs in combined dosage form with acceptable recoveries.

scholarly journals Prediction of test day milk yield by ac method in indigenous Balkan goats in Macedonia

2017 ◽  
Vol 33 (3) ◽  
pp. 299-308 ◽  
Author(s):  
Nikola Pacinovski ◽  
Vladimir Dzabirski ◽  
Georgi Dimov ◽  
Koco Porcu ◽  
Elena Eftimova ◽  
...  
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Accurate Result ◽  
Alternative Method ◽  
The Difference ◽  
Daily Milk Yield ◽  
Selection Of ◽  
Daily Milk

Accurate and precise milk recording is one of the most important moments for a successful selection of milking goats. In this context, breeders are constantly making efforts to find the most suitable and cheapest methods for conducting of tests for milk production. The goal of this research was to compare the A4 method (as referent method) with AC method (as alternative method), for determination of milk production, on the day of recording of the indigenous Balkan goat, in the period of 2014-2016 with milking of goats in the morning and evening. It was determined that the difference between the predicted daily milk yield with one milking (in the morning or evening) and the measured milk yield using the A4 method is too low and almost negligible. With the analysis of all factors (year, lactation and number of milk tests), it was determined that the prediction of total daily milk yield, based on the evening milking, provides more accurate result, in relation to the prediction during morning milking, in cases when using the AC method.

scholarly journals Diagnosis and Stratification of Pseudomonas aeruginosa Infected Patients by Immunochemical Quantitative Determination of Pyocyanin From Clinical Bacterial Isolates

2021 ◽  
Vol 11 ◽  
Author(s):  
Barbara Rodriguez-Urretavizcaya ◽  
Nuria Pascual ◽  
Carme Pastells ◽  
Maria Teresa Martin-Gomez ◽  
Lluïsa Vilaplana ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Limit Of Detection ◽  
Release Kinetics ◽  
Clinical Isolates ◽  
Clinical Samples ◽  
Mueller Hinton ◽  
Highly Sensitive ◽  
Kinetics Of ◽  
Selection Of

The development of a highly sensitive, specific, and reliable immunochemical assay to detect pyocyanin (PYO), one of the most important virulence factors (VFs) of Pseudomonas aeruginosa, is here reported. The assay uses a high-affinity monoclonal antibody (mAb; C.9.1.9.1.1.2.2.) raised against 1-hydroxyphenazine (1-OHphz) hapten derivatives (PC1; a 1:1 mixture of 9-hydroxy- and 6-hydroxy-phenazine-2-carobxylic acids). Selective screening using PYO and 1-OHphz on several cloning cycles allowed the selection of a clone able to detect PYO at low concentration levels. The microplate-based ELISA developed is able to achieve a limit of detection (LoD) of 0.07 nM, which is much lower than the concentrations reported to be found in clinical samples (130 μM in sputa and 2.8 μM in ear secretions). The ELISA has allowed the investigation of the release kinetics of PYO and 1-OHphz (the main metabolite of PYO) of clinical isolates obtained from P. aeruginosa-infected patients and cultured in Mueller–Hinton medium. Significant differences have been found between clinical isolates obtained from patients with an acute or a chronic infection (~6,000 nM vs. ~8 nM of PYO content, respectively) corroborated by the analysis of PYO/1-OHphz levels released by 37 clinical isolates obtained from infected patients at different stages. In all cases, the levels of 1-OHphz were much lower than those of PYO (at the highest levels 6,000 nM vs. 300 nM for PYO vs. 1-OHphz, respectively). The results found point to a real potential of PYO as a biomarker of P. aeruginosa infection and the possibility to use such VF also as a biomarker for patient stratification[2] and for an effective management of these kinds of infections.

Divergent selection for retrieving behavior in mice

1973 ◽  
Vol 51 (1) ◽  
pp. 21-26 ◽  
Author(s):  
J. F. Hurnik ◽  
E. D. Bailey ◽  
F. N. Jerome
Keyword(s):  
Linear Regression ◽  
Inbred Strains ◽  
Divergent Selection ◽  
Regression Functions ◽  
Regression Learning ◽  
The Mean ◽  
The Difference ◽  
Single Regression ◽  
Selection Of

To prove the involvement of genetic factors in retrieving activity, divergent selection was applied for five generations of mice. The mice originated from two highly inbred strains, SWR and C57Bl. In the parental generation, an equal number of reciprocal matings were made between the lines. The selection started in F2 generation. The selection of offspring in both directions was based on the mean performance of the mothers in six trials.Multivariance analysis showed positive response to the selection and confirmed a genetic contribution to the determination of retrieving activity. The estimate of realized heritability, adjusted for inbreeding effects, was lower in the group selected for fast retrieving (h2 = 0.26) and higher in the group selected for slow retrieving (h2 = 0.44). The difference between these coefficients was nonsignificant.In single regression functions on trials, only the linear regression was significant. The linear regression (learning rate) was more pronounced in the group selected for fast retrieving. Within groups, the regression on trials was similar during all five selected generations.

scholarly journals Azocasein Substrate for Determination of Proteolytic Activity: Reexamining a Traditional Method Using Bromelain Samples

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Diego F. Coêlho ◽  
Thais Peron Saturnino ◽  
Fernanda Freitas Fernandes ◽  
Priscila Gava Mazzola ◽  
Edgar Silveira ◽  
...  
Keyword(s):  
Quality Control ◽  
Traditional Method ◽  
Reliable Method ◽  
Limit Of Detection ◽  
Standard Protocol ◽  
Mathematical Approach ◽  
Optimum Conditions ◽  
Limit Of Quantification ◽  
Selection Of

Given the importance of protease’s worldwide market, the determination of optimum conditions and the development of a standard protocol are critical during selection of a reliable method to determine its bioactivity. This paper uses quality control theory to validate a modified version of a method proposed by Charney and Tomarelli in 1947. The results obtained showed that using azocasein substrate bromelain had its optimum at 45°C and pH 9 (Glycine-NaOH 100 mM). We also quantified the limit of detection (LoD) and limit of quantification (LoQ) in the above-mentioned optimum (0.072 and 0.494 mg·mL−1of azocasein, resp.) and a calibration curve that correlates optical density with the amount of substrate digested. In all analysed samples, we observed a significant decrease in response after storage (around 17%), which suggests its use must be immediately after preparation. Thus, the protocol presented in this paper offers a significant improvement, given that subjective definitions are commonly used in the literature and this simple mathematical approach makes it clear and concise.

Improved Polarographic Method for Determination of Glyphosate Herbicide in Crops, Soil, and Water

1985 ◽  
Vol 68 (1) ◽  
pp. 76-79
Author(s):  
Hakon O Friestad ◽  
Jan O Bronstad
Keyword(s):  
Limit Of Detection ◽  
Differential Pulse ◽  
Differential Pulse Polarography ◽  
Good Precision ◽  
Pulse Polarography ◽  
Basic Resin ◽  
Glyphosate Herbicide ◽  
Selection Of ◽  
Better Than

Abstract A prior method for determination of glyphosate in water samples has been modified to accommodate samples of crops and soils. Differential pulse polarography as the determinative step enables analysis in an aqueous medium, which is important during extraction of this compound. Residues are cleaned up and concentrated by ion exchange on a strong basic resin in OH- form. The method is rapid, is applicable to a relatively broad selection of sample types, and gives recoveries consistently better than 60% with good precision. The main shortcoming of the method is that the limit of detection of 0.5-1.0 ppm may sometimes be inadequate. The metabolite, aminomethyl phosphonic acid, is not detected.

Determination of chromium (III) ions in water samples by UV–vis spectrometry based on benzyl-functionalized benzimidazolylidene ligand

2018 ◽  
Vol 18 (6) ◽  
pp. 2081-2091 ◽  
Author(s):  
Zhenning Yan ◽  
Ling Jiang ◽  
Cuiying Xu ◽  
Jianming Liu
Keyword(s):  
Density Functional ◽  
Limit Of Detection ◽  
Environmental Pollutants ◽  
Optimum Conditions ◽  
Functional Theory ◽  
Exothermic Process ◽  
L1 And L2 ◽  
Cation Recognition ◽  
Selection Of

Abstract Chromium is one of the most notorious environmental pollutants. The development of a sensitive and selective chromium detection method is an important issue. In this paper, cation recognition properties of two benzyl-functionalized benzimidazolylidene ligands towards metal ions were investigated by UV–vis spectrophotometry. The results showed that the receptors had a higher selection of Cr3+. The important analytical parameters, such as pH, quantity of the reagents, and their effects on the studied system were investigated. Under the optimum conditions the absorbance of the Cr3+-L complex obeys Beer's law in the Cr3+ concentration range of 0.05–2.60 μg/mL with the limit of detection of 0.026 and 0.034 μg/mL for L1 and L2, respectively. Infrared (IR) spectrum and density functional theory (DFT) calculations were used to explore the coordinating sites and the complex strength of two ligands towards Cr3+. The thermodynamic parameters showed that complex formation is a spontaneous exothermic process. The proposed method was successfully applied to the determination of Cr3+ content in water and alloy samples. The proposed method is seen as a simple and effective way of determining Cr3+ concentration.

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