Simple Analytical Approach Research Articles

Radio-frequency sheath excitation at the extremities of scrape-off layer plasma filaments, mediated by resonant high harmonic fast wave scattering

Resonant filament-assisted mode conversion (FAMC) scattering of high harmonic fast waves (HHFW) by cylindrical field-aligned density inhomogeneities can efficiently redirect a fraction of the launched HHFW power flux into the parallel direction. Within a simplified analytic approach, this contribution compares the parallel propagation, reflection and dissipation of nearly resonant FAMC modes for three magnetic field line geometries in the scrape-off layer, in the presence of radio-frequency (RF) sheaths at field line extremities and phenomenological wave damping in the plasma volume. When a FAMC mode, excited at the HHFW antenna parallel location and guided along the open magnetic field lines, impinges onto a boundary at normal incidence, we show that it can excite sheath RF oscillations, even toroidally far away from the HHFW launcher. The RF sheaths then dissipate part of the power flux carried by the incident mode, while another part reflects into the FAMC mode with the opposite wave vector parallel to the magnetic field. The reflected FAMC mode in turn propagates and can possibly interact with the sheath at the opposite field line boundary. The two counter-propagating modes then form in the bounded magnetic flux tube a lossy cavity excited by the HHFW scattering. We investigate how the presence of field line boundaries affects the total HHFW power redirected into the filament, and its splitting between sheath and volume losses, as a function of relevant parameters in the model.

Numerical study on the stiffness and ultimate strength of cold-formed steel C-shaped connectors under pull-out failure

ABSTRACT In this paper, cold-formed steel C-shaped connectors, as one of the most commonly used components in steel wall/framing systems, were investigated under the pull-out failure modes using a detailed numerical study. Finite element models were validated using the data obtained from an experimental program; and the results were compared with the current design equations. Finally, a new pull-out strength equation was proposed based on the critical parameters affecting the behaviour of C-shaped connectors. In addition, initial bending stiffness of C-shaped connectors was studied using a simplified analytical approach; and the results obtained from the proposed new stiffness equation were compared with the initial slope of experimental and numerical force-displacement curves. These comparisons confirm the accuracy of the new strength and stiffness equations in order to apply to the analytical methods such as component-based method in future works.

Nickel hydroxide nanoflower-based dispersive solid-phase extraction of copper from water matrix.

In this work, a dispersive solid-phase extraction method based on Ni(OH)2 nanoflowers (Ni(OH)2-NFs-DSPE) was developed to separate and preconcentrate copper ions from tap water samples for determination by flame atomic absorption spectrometry (FAAS). Ni(OH)2-NFs was synthesized using a homogeneous precipitation technique and used as sorbent for copper preconcentration. X-ray diffraction, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to characterize the synthesized sorbent. All experimental variables were carefully optimized to achieve a high enhancement factor of 107.5-folds with respect to the detection sensitivity of the conventional FAAS. The proposed method's analytical parameters including LOD, LOQ, and linear range were determined as 1.33μg/L, 4.42μg/L, and 3.0-40μg/L, respectively. To assess the applicability and reliability of the developed method, optimal conditions were applied to tap water samples and satisfactory percent recoveries (94-103%) were obtained for the samples spiked at 20 and 30μg/L. This validated the accuracy and feasibility of the developed method to real samples. The developed method can be described as a simple, efficient, and rapid analytical approach for the accurate determination of trace copper ions in water samples.

Design and Fabrication of a Gas Sensor Based on a Polypyrrole/Silver Nanoparticle Film for the Detection of Ammonia in Exhaled Breath of COVID-19 Patients Suffering from Acute Kidney Injury.

One of the serious complications of COVID-19 is acute kidney injury (AKI), leading to a decrease in kidney function and even death. The concentration of ammonia (NH3) in the exhaled breath (EB) of COVID-19 patients suffering from AKI symptoms will be significantly increased. In this work, the detection of breath NH3 was performed at gold interdigital electrodes modified with a soluble polypyrrole microparticle and silver nanoparticle film (Au-IDEs/S-PPyMPs/AgNPs) as a noninvasive chemiresistor gas sensor. The response behavior of unmodified and modified gas sensors toward NH3 and other interfering compounds was studied. The Au-IDEs/S-PPyMPs/AgNPs exhibited NH3 detection in the linear dynamic range of 1.00-19.23 ppm, with a limit of detection of 0.12 ppm. Finally, the fabricated gas sensor was used to monitor the NH3 concentration in the EB of COVID-19 patients suffering from AKI symptoms. For this purpose, the gas sensor was validated in 19 EB samples (seven COVID-19-positive patients, four COVID-19-negative patients, and eight post-COVID-19 patients). The gas sensor was directly exposed to the EB samples, followed by recording the changes in electrical resistance via a low-cost digital multimeter. The sensing mechanism was explained as the interaction between breath NH3 and sensing materials. The breath NH3 concentrations have a desirable correlation (R2 = 0.8463) with the estimated glomerular filtration rate (eGFR) values in COVID-19-positive patients. The fabricated gas sensor can distinguish COVID-19-positive patients suffering from AKI symptoms from COVID-19-negative patients and post-COVID-19 patients. The present work can pave the way for the development of a simple and efficient analytical approach for COVID-19 patients with AKI without the need for sample pretreatment.

IR side of positivity bounds

We show how calculable IR loop effects impact positivity bounds in Effective Field Theories with causal and unitary UV completions. We identify infrared singularities which appear in dispersion relations at $|t|\lesssim m^2$. In the massless limit, they weaken two-sided bounds based on crossing symmetry, such as the lower bound on the amplitude for Galileon scattering. For amplitudes that are analytic in $s$ even for large negative $t$, i.e. $|t|\gg m^2$, we propose a new simple analytic approach to dispersive bounds, which are instead insensitive to the singularities, and explicitly compute the finite contributions from loops. Finally we show that the singularity do not affect the bounds based on smearing in impact parameter.

Synthesis of red emissive copper nanoclusters with 2-mercaptopyrimidine for promoting selective and sensitive fluorescent sensing of creatinine as a kidney disease biomarker in biofluids

Fluorescent metal nanoclusters synthesized from organic ligands have been proved best sensing tools for the detection of biologically active species. In this work, we have designed a simple one-step strategy for the preparation of red fluorescent copper nanoclusters (Cu NCs) using 2-mercaptopyrimidine (2-MPY). The 2-MPY-Cu NCs act as an efficient probe for promoting selective and sensitive fluorescence recognition of creatinine as a biomarker in biofluids. The as-prepared 2-MPY-Cu NCs exhibit a strong emission peak at 728 nm when excited at 390 nm. It is observed that several interactions (intramolecular H-bonding and π-π) between 2-MPY-Cu NCs and creatinine, leading to a dramatic fluorescence quenching (∼92 %), which promotes for fluorescent sensing of creatinine. As a result, 2-MPY-Cu NCs display remarkable quantitative fluorescence response to creatinine concentration (0.0625 × 10-6 to 5 × 10-6 mol/dm−3(−|-)) with the detection limit of 9.91 × 10-9 mol/dm−3(−|-). The developed analytical strategy was applied to assay creatinine in biofluids with promising analytical results. This method offers a simple and rapid analytical approach for fluorescent sensing of creatinine in real samples.

Interaction analysis of two floating granular piled raft units

ABSTRACT The pile–soil–raft interactions remain a daunting problem in the study of piled-raft foundations. A simple analytical continuum approach is implemented in the present research to analyse the interaction between two granular floating piled-rafts. The formulation uses the equations of Mindlin and Boussinesq for the estimation of the displacements for forces in the interior and on the surface of the continuum. Settlement influence factor, interaction factor, the normalised shear stresses along the granular pile (GP)-soil interface, the percentage load shared by GP, the percentage load transferred to the GP base, and the normalised contact pressure distribution underneath the raft are evaluated and presented for design.

Elasto-capillary necking, bulging and Maxwell states in soft compressible cylinders

Localized pattern formations and “two-phase” deformations are studied theoretically in soft compressible cylinders subject to surface tension and axial loading through several force-controlled loading scenarios. By drawing upon known results for separate yet mathematically similar elastic localization problems, a concise family of analytical bifurcation conditions for localized bulging or necking are derived in terms of a general compressible strain energy function. The effect of material compressibility and strain-stiffening behaviour on the bifurcation point is analysed, and comparisons between our theoretical bifurcation conditions and the corresponding numerical simulation results of Dortdivanlioglu and Javili (Extreme Mech. Lett. 55, 2022) are made. It is then explained how the fully developed “two-phase” (Maxwell) state which evolves from the initial localized bifurcation solution can be comprehensively understood using the simple analytical expressions for the force parameters corresponding to the primary axial tension deformation. The power of this simple analytical approach in validating numerical simulation results for elastic localization and phase-separation-like problems of this nature is highlighted.

DEVELOPMENT AND VALIDATION OF THE RP-HPLC METHOD FOR ESTIMATION OF CILNIDIPINE IN RAT PLASMA

Objective: A simple, precise, accurate, robust, and reliable RP-HPLC technique for detecting cilnidipine in Wistar rat plasma was developed and validated. Methods: The chromatographic separation was performed using the C-18 reverse phase column Oyster BDS Premium C18 column (4.6 × 150 mm, 5 µm particle size). The flow rate was set to 1.2 ml/min, and the chromatogram was recorded at 240 nm. The proposed method was validated in compliance with the International Conference on Harmonization (ICH) guidelines. Results: The calibration curves plotted were found to be linear over the concentration range of 40-200 ng/ml in Wistar rat plasma, with a regression coefficient of R2>0.999, suggesting that the linearity was within limits. The LOD and LOQ of the present method were found to be 2.184 and 4.518 ng/ml, respectively. Drug extraction recoveries from Wistar rat plasma were found to be >98%. Conclusion: Using Wistar rat plasma, a simple, fast, specific, accurate, and precise analytical approach was developed and validated. The technique was validated according to the ICH guidelines. The obtained results show that the suggested technique can be simply and effectively utilized for routine cilnidipine analysis in Wistar rat plasma.

Purge and trap in-tube colorimetric detection method for the determination of ethanol in alcoholic and non-alcoholic beverages

• Purge and trape coupled with smartphone-based detection were for the first time introduced for ethanol analysis. • Improvements in mass transfer efficiency were achieved with low reagent consumption. • The methodology showed good reproducibility with low operational costs. • The workflow is easily performed and it is suitable for low-source countries. • A low limit of detection (0.05 %v/v) was achieved. A simple and cost-effective analytical approach based on the combination of purge and trap technique coupling with smartphone-based image analysis was developed for the sensitive detection of ethanol. Herein, the dichromate solution was used as the detection reagent to determine the ethanol concentration in alcoholic beverages. The ethanol from the sample solution was purged by the airstream and then trapped into a 1-mL Eppendorf tube containing the detection reagent. During the process, ethanol is oxidized by dichromate reagent to form ethanoic acid, and the orange color of the dichromate ion is started to become darker after one minute. The color image of the Eppendorf tube was taken by smartphone in a controlled-light box and then analyzed by the laptop ImageJ software. Experimental parameters affecting the method sensitivity, such as extraction time, stirring rate, and dichromate concentration, were studied. Under the optimal conditions, the calibration curve was linear for the ethanol concentrations ranging from 0.15 and 3.0 %v/v (R 2 >0.993). The limit of detection of 0.05 %v/v was obtained. The intra- and inter-assay results (RSD%) were less than 1.0% and 2.0%, respectively. The developed approach has been successfully applied to determine ethanol percentage in beverage samples (alcoholic beer, brandy, and non-alcoholic beer), with relative recoveries ranging from 86-112%. Finally, the accuracy was assessed by comparison of the results obtained by our method and the UV-Vis spectrophotometric method, which agreed at the 95% confidence level.

Flexural performance of CFRP strengthened beams - comparison with analytical model

ABSTRACT In recent years, strengthening methods for reinforced concrete structures using fibre-reinforced polymer (FRP) composites have been gaining widespread interest and growing acceptance in civil engineering industry. Near surface mounted (NSM) reinforcement as well as externally bonded reinforcement (EBR) sheets have emerged as new strengthening methods in which external reinforcement (in the form of bars or sheets) is embedded into grooves or adhered to the section with epoxy adhesive. This paper proposes a simplified analytical approach to predict flexural behaviour of simply supported reinforced-concrete (RC) beams strengthened with carbon fibre-reinforced polymer (CFRP) using the above-mentioned methods. The flexural capacity and deformational behaviour of FRP strengthened beams are analysed using trilinear moment curvature relationship at three critical points namely (i) crack initiation point (ii) steel yield initiation point and (iii) ultimate capacity point, based on strain compatibility and principles of equilibrium. A good predictive performance of analytical model is appraised by simulating force-deflection response registered in the experimental program composed of RC beams strengthened with NSM as well as EBR methods. The analytical solutions have also given accurate prediction of experimental results in the literature regardless of the arrangement of CFRP reinforcement.

"Market Integration and Seasonal Prices of Paddy: An Economic Analysis"

To frame an inclusive agricultural policy, analysis of price and market arrivals overtime is essential. Variations in market arrivals mainly leads to price instability. Such study is beneficial for farmers in demand to select the appropriate time to sell their farm produce to get best economic profits. On this sight the present study was undertaken to examine the seasonality and market integration of Paddy in Gadchiroli District of Maharashtra. The secondary data were collected for a period of 15 years from 2006 to 2020. Data were analysed using simple tabular analytical tools and functional analysis approaches. The data showed a highest seasonal indices of arrivals in the month of January and lowest in month of August in Chamorshi and Gadchiroli markets, respectively. In terms of paddy price, the highest and lowest seasonal indices of prices were seen in the months of July and March in Chamorshi market where as in the months of September and March in Gadchiroli market. Contradictory relationship between arrival and prices was witnessed in the designated markets. The degree of integration was found strong and positive of prices. Transparency in price signal among both markets resulted in strong integration. For better operations of well integrated markets, there should be provision of more investments and for the less integrated markets, need of adoption of online marketing system and awareness creation is needed to eliminate the malpractices in agricultural markets. These results recommend market integration and competition rather than collusions of markets in the study area.

Malachite Green Optical Sensor Based on Electrospun Polyimide Nanofiber

Malachite green (MG) is a triphenylmethane cationic dye used in aquaculture practice, although it has been banned in several countries. The illegal use by fish producers, however, persists due to its effectiveness, and ready and cheap supply. To prevent indiscriminate applications, strict control measures with simple analytical approaches are therefore necessary. With this purpose, a novel, cheap and simple method applying electrospun polyimide nanofibers was developed and validated for MG control in water by color image analysis. For detection, a simple apparatus and ImageJ® software to treat images captured by common smartphones were used. A detection limit of 0.013 mg/L with a linear analytical response range within the concentration of 0.05 to 0.3 mg/ L of malachite green (MG) with a correlation coefficient of 0.997 and standard deviation (n = 9) varying from 1.01 to 3.92% was achieved with the proposed method. Accuracy was assessed by recovery assays in water samples and percentages of 96.6 to 102.0% were obtained. The method is robust and suitable for the rapid and reliable monitoring of MG in water.

A fluorescence biosensor based on double-stranded DNA and a cationic conjugated polymer coupled with exonuclease III for acrylamide detection

As a toxic substance on human health produced in food thermal treatment, simple analytical approaches are highly desired for the detection of acrylamide (ACR) in foods. With the aid of exonuclease III (Exo III), a simple fluorescence sensor was proposed based on carboxyfluorescein-labeled double-stranded DNA (FAM-dsDNA) and a cationic conjugated polymer (PFP). Fluorescence resonance energy transfer (FRET) efficiency between FAM and PFP was changed with and without ACR. When ACR was present, ACR and single-stranded DNA (P1, ssDNA) formed an adduct, allowing free FAM-labeled complementarity strand DNA (P2, FAM-csDNA) to appear in the solution and avoiding the digestion of P2 by Exo III. After the addition of PFP, the interaction of PFP and FAM induced strong FRET. Under optimized conditions, ACR was detected with a limit of detection (LOD) of 0.16 μM. According to this biosensor, a LOD of 1.3 μM in water extract samples was observed with a good recovery rate (95–110 %).

Analytical Approach for Estimation of Wave Transmission Coefficient for Π-Shaped Floating Breakwater

This study presents a simplified analytical approach, based on power transmission theory, to estimate the transmission coefficient of a π-shaped floating breakwater (FB) with finite width. In evaluating the transmitted wave power, this approach considers both the incident wave kinetic power and the heave oscillation of the FB. Additional power due to the acceleration of the floating body and the hydrodynamic mass increases the transmitted wave power behind the FB and consequently increases the transmission coefficient. The proposed theoretical approach is validated using laboratory-scale experimental data obtained from the literature for π-shaped FB. The results of the proposed approach are in good to excellent agreement with those of experimental studies. In addition, the reliability of the proposed approach is assessed by comparing its results with those of other theoretical models. The effects of sea depth, relative draft, and incident wave height on the magnitude of the transmission coefficient are examined. It is found that the effect of the incident wave height distinguishes the proposed model from others in the existing literature.

A simplified analytical approach for the clear height in compartment fire based on a two‐layer zone model

AbstractCompartment fire is an important research area in fire science and fire safety. Owing to its simplicity, the zone model remains attractive in studying compartment fire. Although computer software packages for the two‐layer zone are in popular use, a basic understanding of the physical phenomena involved and the mathematical formulation thereon would benefit users of the zone model in terms of critical judgement of software outputs, which could be unreasonable, and insight of the general trends of important variables. In general, the differential equations based on a two‐layer zone model have no analytical solutions and numerical methods are required. However, stiffness is present in using numerical methods to solve these differential equations, and reliable results are obtained only when very small time steps are used in computation. Nevertheless, in some special cases, analytical solution for the clear height in the zone model exists, as demonstrated in the present study. Predicted values of smoke layer height in the present approach are shown to be in good agreement with experimental results reported in the literature. The present work would provide insight into the tenability condition of a compartment on fire and is an important issue in fire safety management.

Enhanced Sample Throughput Capillary Zone Electrophoresis with UV Detection in Hydrodynamically Closed System for Determination of Ibuprofen

A simple analytical approach based on capillary zone electrophoresis with ultraviolet detection and repeated sample injection strategy (applied in a hydrodynamically closed separation system for the first time) was developed for the determination of ibuprofen (IBU) in commercially available pharmaceutical preparations. The proposed method was characterized by significantly increased sample throughput and favorable validation parameters, highly demanded in routine quality control laboratories. The limit of detection was predicted at the concentration level of 0.31 µg/mL. Intra-day precision expressed as the relative standard deviation of IBU concentration ranged from 1.9 to 5.6%, and corresponding intra-day accuracy expressed as the relative error was in the interval of 87.1–106.5%. Inter-day precision was in the range of 2.6–15.0%, and inter-day accuracy was 94.9–102.7%. The developed method was able to quantify IBU in complex pharmaceutical matrices represented by commercially available tablets and oral suspension. The determined contents of IBU in the tested dosage forms were in good agreement with the manufacturer’s declaration. The analytical performance of the developed method was evaluated according to the innovative RGB Additive Color Model strategy. It was demonstrated that the proposed method is characterized by very good analytical performance parameters, safety and eco-friendliness, and practical effectiveness.

Torrential Hazard Prevention in Alpine Small Basin through Historical, Empirical and Geomorphological Cross Analysis in NW Italy

Debris flow is one of the most dangerous natural processes in mountain regions and it occur in a wide variety of environments throughout the world. In the Italian Alps, some tens of thousands of damaging debris flow and, in general, torrential floods associated to intense sediment transport in secondary catchments have been documented in the last 300 years. These have caused socio-economic damage, damage to anthropogenic structures or infrastructures and in many cases casualties. Often, in the same basins, the occurrence of debris-flow processes recurs many years later. Prediction can often be spatial and based on the magnitude of the largest known process, while the temporal forecast is the most uncertain. It is also possible to increase the resilience of the population and of the territory. The present study aims at investigating different levels of debris-flow hazard in urban areas on Alpine alluvial fans and proposes a strategy for debris-flow prevention based on historical research and on a simplified analytical approach, methods that also involve relatively low costs. For such analysis, Ischiator stream catchment (ca. 20 km2) and its alluvial fan (NW Italy) were selected. This area was partly affected by historical torrential flood associated to intense sediment transport and debris-flow processes. Present-day instability conditions along the slope and the stream network were detected and synthesized through surveys and aerial photo interpretation integrated by satellite images (period 1954–2021). An estimation of the potential amount of moving detritus, referred to as debris flow, was carried out regarding the June 1957 debris-flow event, based on the predictive models. The individual hazard index value was estimated based on different methods. The results indicate that 56% of the area is exposed to flood associated to intense sediment transport hazard, which fluctuates from high to very high levels; such results are supported by debris-flow historical records. Since today almost half of the settlement (Bagni di Vinadio) is located on potentially risk-exposed areas, the urban evolution policy adopted after the 1957 event failed to manage the risk connection to debris-flow activity.

Mechanical properties of built-up timber beams with various cross sections determined using analytical methods

ABSTRACT In this study, analytical methods were used to investigate the performance of built-up timber (BT) beams with different designs. A simplified analytical approach based on the gamma and capacity methods was used to evaluate the initial stiffness, allowable strength, and ultimate strength of BT beams. Current analytical methods cannot be used to estimate the ductility ratio, thus hampering the development of a complete analytical model for BT beams. In this study, a complete analytical model was established for BT beams. In this model, the ductility ratio is determined according to experimental results. The ductility ratios of specimens were determined using the equivalent energy method. The developed complete analytical model for BT beams can accurately model the behavior of these beams. The estimated ductility ratios suggest that specimens with one web and two webs are suitably ductile and marginally brittle, respectively. The developed model can be used to predict the flexural performance of BT beams with different design parameters, and the ductility ratio can be applied in structural design.

Rapid authentication of stingless bees (Heterotrigona itama) honey by UV spectroscopy and hierarchical cluster analysis

The price of stingless bee (Heterotrigona itama) honey is almost twice higher than the one produced by a non-stingless bee (Apis mellifera) due to its limited production and high content of polyphenol and flavonoids compounds. However, in the market, the authentication of stingless bees and non-stingless bees honey becomes difficult due to the similarity in the color of honey and its sugar content. In this research, we propose a simple analytical approach by combining ultraviolet (UV) spectroscopy and hierarchical cluster analysis (HCA) for discrimination between stingless and non-stingless bee honey. Fifty samples of monofloral stingless bee (Heterotrigona itama) honey and non-stingless bee (Apis mellifera) honey from Acacia mangium was used. The samples were diluted with a distilled water at a proportion of 1:30 (volume/volume). The spectral data were acquired in the range of 190-1100 nm using a benchtop UV-Vis spectrometer with fast scanning mode. The HCA was applied for selected preprocessed spectral data in the range of 230-400 nm. The result shows that HCA could be effective to discriminate between stingless and non-stingless bee honey. Shortly, it is expected to realize the simple and quick analytical method to authenticate stingless bee honey based on UV spectroscopy and the HCA method.