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Keywords = linear Stark effect

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20 pages, 675 KiB  
Article
Assessment of Endometriosis Knowledge and Its Determinants Among Nurses in Al-Jouf Region, Saudi Arabia
by Nadia Bassuoni Elsharkawy, Afrah Madyan Alshammari, Osama Mohamed Elsayed Ramadan, Enas Mahrous Abdelaziz, Mohamed E. H. Elzeky, Alaa Hussain Hafiz, Mary Faleh Alrowily, Sultan Muharib Alruwaili and Lareen Magdi El-Sayed Abo-Seif
Healthcare 2025, 13(12), 1386; https://doi.org/10.3390/healthcare13121386 - 11 Jun 2025
Viewed by 574
Abstract
Background/Objectives: Endometriosis, a chronic and debilitating gynecological disorder, exacts a heavy clinical and socioeconomic toll on women’s lives. Despite its prevalence, its timely diagnosis and effective management are hindered by pervasive knowledge gaps among frontline nursing professionals, and these are especially pronounced [...] Read more.
Background/Objectives: Endometriosis, a chronic and debilitating gynecological disorder, exacts a heavy clinical and socioeconomic toll on women’s lives. Despite its prevalence, its timely diagnosis and effective management are hindered by pervasive knowledge gaps among frontline nursing professionals, and these are especially pronounced in under-researched regions such as Al-Jouf, Saudi Arabia. Aim: Guided by the Knowledge–Attitude–Practice model, this study aimed to assess the level of endometriosis-related knowledge among nurses in the Al-Jouf region of Saudi Arabia and to identify the sociodemographic and professional determinants of knowledge levels. Methods: A cross-sectional, descriptive-analytical design was employed between January and July 2024, enrolling 215 nurses from a principal maternity and children’s hospital and two primary healthcare centers in Sakaka. A rigorously validated, bilingual 20-item questionnaire assessing four domains (definition, risk factors, clinical manifestations, and treatment goals) was administered. Data were analyzed using descriptive statistics, multiple linear regression, and binary logistic regression to elucidate predictors of knowledge. Results: A concerning picture emerged: 61% of participants scored below 60% (indicative of low knowledge), with only 6% achieving high scores. Higher educational attainment proved the strongest predictor (β = 0.415, p < 0.001), followed by age (β = 0.232, p < 0.001), years of experience (β = 0.149, p = 0.041), and direct patient care exposure (β = 0.168, p = 0.021). Collectively, these factors explained 37.6% of the variance in knowledge scores, underscoring a critical deficit in endometriosis management preparedness. Conclusions: The stark deficiencies in endometriosis knowledge among nurses in Al-Jouf call for immediate, tailored educational and policy interventions. Strengthening clinical competencies is essential for fostering early diagnosis and improving care outcomes for women burdened by this complex condition. Full article
(This article belongs to the Special Issue From Evidence-Based Practice to Knowledge Translation in Nursing Care)
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26 pages, 5156 KiB  
Article
Integrative Assessment of Surface Water Contamination Using GIS, WQI, and Machine Learning in Urban–Industrial Confluence Zones Surrounding the National Capital Territory of the Republic of India
by Bishnu Kant Shukla, Lokesh Gupta, Bhupender Parashar, Pushpendra Kumar Sharma, Parveen Sihag and Anoop Kumar Shukla
Water 2025, 17(7), 1076; https://doi.org/10.3390/w17071076 - 4 Apr 2025
Viewed by 1179
Abstract
This study proposes an innovative framework integrating geographic information systems (GISs), water quality index (WQI) analysis, and advanced machine learning (ML) models to evaluate the prevalence and impact of organic and inorganic pollutants across the urban–industrial confluence zones (UICZ) surrounding the National Capital [...] Read more.
This study proposes an innovative framework integrating geographic information systems (GISs), water quality index (WQI) analysis, and advanced machine learning (ML) models to evaluate the prevalence and impact of organic and inorganic pollutants across the urban–industrial confluence zones (UICZ) surrounding the National Capital Territory (NCT) of India. Surface water samples (n = 118) were systematically collected from the Gautam Buddha Nagar, Ghaziabad, Faridabad, Sonipat, Gurugram, Jhajjar, and Baghpat districts to assess physical, chemical, and microbiological parameters. The application of spatial interpolation techniques, such as kriging and inverse distance weighting (IDW), enhances WQI estimation in unmonitored areas, improving regional water quality assessments and remediation planning. GIS mapping highlighted stark spatial disparities, with industrial hubs, like Faridabad and Gurugram, exhibiting WQI values exceeding 600 due to untreated industrial discharges and wastewater, while rural regions, such as Jhajjar and Baghpat, recorded values below 200, reflecting minimal anthropogenic pressures. The study employed four ML models—linear regression (LR), random forest (RF), Gaussian process regression (GPR), and support vector machines (SVM)—to predict WQI with high precision. SVM_Poly emerged as the most effective model, achieving testing CC, RMSE, and MAE values of 0.9997, 11.4158, and 5.6085, respectively, outperforming RF (0.9925, 29.8107, 21.7398) and GPR_PUK (0.9811, 68.4466, 54.0376). By leveraging machine learning models, this study enhances WQI prediction beyond conventional computation, enabling spatial extrapolation and early contamination detection in data-scarce regions. Sensitivity analysis identified total suspended solids as the most critical predictor influencing WQI, underscoring its relevance in monitoring programs. This research uniquely integrates ML algorithms with spatial analytics, providing a novel methodological contribution to water quality assessment. The findings emphasize the urgency of mitigating the fate and transport of organic and inorganic pollutants to protect Delhi’s hydrological ecosystems, presenting a robust decision-support system for policymakers and environmental managers. Full article
(This article belongs to the Special Issue Environmental Fate and Transport of Organic Pollutants in Water)
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18 pages, 2721 KiB  
Article
Implementation of National Nutrition Policies and Strategies to Reduce Unhealthy Diets: An Ecological Analysis of 194 Countries from 2017 to 2021
by Alina Ioana Forray and Cristina Maria Borzan
Nutrients 2024, 16(6), 911; https://doi.org/10.3390/nu16060911 - 21 Mar 2024
Cited by 3 | Viewed by 3077
Abstract
This study investigates the implementation of national policies and strategies to control unhealthy diets, which are pivotal in the global surge of non-communicable diseases. Leveraging data from the World Health Organization’s Non-Communicable Diseases Progress Monitors and Country Capacity Surveys, we calculated aggregate implementation [...] Read more.
This study investigates the implementation of national policies and strategies to control unhealthy diets, which are pivotal in the global surge of non-communicable diseases. Leveraging data from the World Health Organization’s Non-Communicable Diseases Progress Monitors and Country Capacity Surveys, we calculated aggregate implementation scores for 13 diet-related policies across 194 countries from 2017 to 2021. We used descriptive statistics and linear regression to investigate the implementation trends and associations between key national-level factors and implementation scores. The mean score in 2021 was 52% (SD = 24), with no statistical differences in the 5-year period. Stark disparities in implementation efficacy were noted, ranging from comprehensive adoption in some nations to minimal application in others. Our analysis also highlights a shifting focus in policy adoption: notably, an increased commitment to taxing sugar-sweetened beverages juxtaposed with a decline in dietary awareness initiatives. Significant predictors of policy implementation include the Human Development Index, the cost of a healthy diet, and health service coverage. These findings suggest a complex interdependence of socioeconomic factors influencing policy implementation. Our research underscores the need for multifaceted, globally collaborative strategies to effectively combat diet-related diseases, emphasizing the importance of comprehensive policy frameworks in public health interventions. Full article
(This article belongs to the Section Nutritional Policies and Education for Health Promotion)
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16 pages, 7770 KiB  
Communication
Chaotic Vibration and Perforation Effects on the Sound Absorption of a Nonlinear Curved Panel Absorber
by Yiu-Yin Lee
Mathematics 2023, 11(14), 3178; https://doi.org/10.3390/math11143178 - 20 Jul 2023
Cited by 1 | Viewed by 1279
Abstract
This study is the first to investigate the effect of chaotic vibration on the sound absorption of a curved perforated panel. Previous studies on the effect of nonlinear vibration on the sound absorption of a panel absorber have focused on periodic responses only. [...] Read more.
This study is the first to investigate the effect of chaotic vibration on the sound absorption of a curved perforated panel. Previous studies on the effect of nonlinear vibration on the sound absorption of a panel absorber have focused on periodic responses only. In this study, a sound absorption formula was derived by considering the panel impedance and perforation impedance. The numerical integration method was adopted to generate various chaotic vibrational responses, which were used to compute the corresponding sound absorptions. Several interesting findings that have never been observed in any previous studies on acoustic absorption were derived. First, in the chaotic and highly nonlinear cases, as the excitation frequency increased, the corresponding response frequencies decreased. This was opposite to the typical trend in linear cases, in which higher excitation frequencies corresponded to higher response frequencies. Second, in chaotic cases, absorption mainly occurred due to panel vibration effects. This is also in stark contrast to the findings of studies on perforated vibrating panels, in which the absorption effect mainly originates from perforations. Additionally, the absorption bandwidths are much wider and can shift to higher frequencies; however, the peak absorption coefficients were approximately 20% lower than in the case of the perforation effect only. Third, in the quasi-chaotic case, the absorption curve in the case of the perforation effect plus the vibration effect was between the absorption curves of the perforation effect only and the perforation effect plus the vibration effect. Full article
(This article belongs to the Special Issue Mathematical Modeling and Simulation of Oscillatory Phenomena)
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23 pages, 6773 KiB  
Article
Quantum Confined Stark Effect on the Linear and Nonlinear Optical Properties of SiGe/Si Semi Oblate and Prolate Quantum Dots Grown in Si Wetting Layer
by Varsha, Mohamed Kria, Jawad El Hamdaoui, Laura M. Pérez, Vinod Prasad, Mohamed El-Yadri, David Laroze and El Mustapha Feddi
Nanomaterials 2021, 11(6), 1513; https://doi.org/10.3390/nano11061513 - 8 Jun 2021
Cited by 19 | Viewed by 3666
Abstract
We have studied the parallel and perpendicular electric field effects on the system of SiGe prolate and oblate quantum dots numerically, taking into account the wetting layer and quantum dot size effects. Using the effective-mass approximation in the two bands model, we computationally [...] Read more.
We have studied the parallel and perpendicular electric field effects on the system of SiGe prolate and oblate quantum dots numerically, taking into account the wetting layer and quantum dot size effects. Using the effective-mass approximation in the two bands model, we computationally calculated the extensive variation of dipole matrix (DM) elements, bandgap and non-linear optical properties, including absorption coefficients, refractive index changes, second harmonic generation and third harmonic generation as a function of the electric field, wetting layer size and the size of the quantum dot. The redshift is observed for the non-linear optical properties with the increasing electric field and an increase in wetting layer thickness. The sensitivity to the electric field toward the shape of the quantum dot is also observed. This study is resourceful for all the researchers as it provides a pragmatic model by considering oblate and prolate shaped quantum dots by explaining the optical and electronic properties precisely, as a consequence of the confined stark shift and wetting layer. Full article
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13 pages, 923 KiB  
Article
From the Vector to Scalar Perturbations Addition in the Stark Broadening Theory of Spectral Lines
by Valery Astapenko, Andrei Letunov and Valery Lisitsa
Universe 2021, 7(6), 176; https://doi.org/10.3390/universe7060176 - 2 Jun 2021
Cited by 5 | Viewed by 2253
Abstract
The effect of plasma Coulomb microfied dynamics on spectral line shapes is under consideration. The analytical solution of the problem is unachievable with famous Chandrasekhar–Von-Neumann results up to the present time. The alternative methods are connected with modeling of a real ion Coulomb [...] Read more.
The effect of plasma Coulomb microfied dynamics on spectral line shapes is under consideration. The analytical solution of the problem is unachievable with famous Chandrasekhar–Von-Neumann results up to the present time. The alternative methods are connected with modeling of a real ion Coulomb field dynamics by approximate models. One of the most accurate theories of ions dynamics effect on line shapes in plasmas is the Frequency Fluctuation Model (FFM) tested by the comparison with plasma microfield numerical simulations. The goal of the present paper is to make a detailed comparison of the FFM results with analytical ones for the linear and quadratic Stark effects in different limiting cases. The main problem is connected with perturbation additions laws known to be vector for small particle velocities (static line shapes) and scalar for large velocities (the impact limit). The general solutions for line shapes known in the frame of scalar perturbation additions are used to test the FFM procedure. The difference between “scalar” and “vector” models is demonstrated both for linear and quadratic Stark effects. It is shown that correct transition from static to impact limits for linear Stark-effect needs in account of the dependence of electric field jumping frequency in FFM on the field strengths. However, the constant jumping frequency is quite satisfactory for description of the quadratic Stark-effect. The detailed numerical comparison for spectral line shapes in the frame of both scalar and vector perturbation additions with and without jumping frequency field dependence for the linear and quadratic Stark effects is presented. Full article
(This article belongs to the Special Issue Advances in Understanding Astrophysical and Atomic Phenomena)
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8 pages, 413 KiB  
Communication
Classical Dynamics of Rydberg States of Muonic-Electronic Helium and Helium-Like Ions in a Weak Electric Field: Counter-Intuitive Linear Stark Effect
by Eugene Oks
Dynamics 2021, 1(1), 1-8; https://doi.org/10.3390/dynamics1010001 - 23 Mar 2021
Viewed by 2649
Abstract
According to the existing paradigm, helium atoms and helium-like ions (hereafter, heliumic systems) in a relatively weak external static electric field do not exhibit the linear Stark effect—in distinction to hydrogen atoms and hydrogen-like ions. In the present paper we consider the classical [...] Read more.
According to the existing paradigm, helium atoms and helium-like ions (hereafter, heliumic systems) in a relatively weak external static electric field do not exhibit the linear Stark effect—in distinction to hydrogen atoms and hydrogen-like ions. In the present paper we consider the classical dynamics of a muonic-electronic heliumic system in Rydberg states–starting from the concept from our previous paper. We show that there are two states of the system where the averaged electric dipole moment is non-zero. Consequently, in these states the heliumic system should exhibit the linear Stark effect even in a vanishingly small electric field, which is a counter-intuitive result. We also demonstrate the possibility of controlling the overall precession of the electronic orbit by an external electric field. In particular, we show the existence of a critical value of the external electric field that would “kill” the precession and make the electronic orbit stationary. This is another counter-intuitive result. We calculate analytically the value of the critical field and show that it is typically smaller or even much smaller than 1 V/cm. Full article
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17 pages, 3972 KiB  
Review
Hybrid Dual-Polarization Synthetic Aperture Radar
by R. Keith Raney
Remote Sens. 2019, 11(13), 1521; https://doi.org/10.3390/rs11131521 - 27 Jun 2019
Cited by 48 | Viewed by 8667
Abstract
Compact polarimetry for a synthetic aperture radar (SAR) system is reviewed. Compact polarimetry (CP) is intended to provide useful polarimetric image classifications while avoiding the disadvantages of space-based quadrature-polarimetric (quad-pol) SARs. Two CP approaches are briefly described, π/4 and circular. A third form, [...] Read more.
Compact polarimetry for a synthetic aperture radar (SAR) system is reviewed. Compact polarimetry (CP) is intended to provide useful polarimetric image classifications while avoiding the disadvantages of space-based quadrature-polarimetric (quad-pol) SARs. Two CP approaches are briefly described, π/4 and circular. A third form, hybrid compact polarimetry (HCP) has emerged as the preferred embodiment of compact polarimetry. HCP transmits circular polarization and receives on two orthogonal linear polarizations. When seen through its associated data processing and image classification algorithms, HPC’s heritage dates back to the Stokes parameters (1852), which are summarized and explained in plain language. Hybrid dual-polarimetric imaging radars were in the payloads of two lunar-orbiting satellites, India’s Earth-observing RISAT-1, and Japan’s ALOS-2. In lunar or planetary orbit, a satellite equipped with an HCP imaging radar delivers the same class of polarimetric information as Earth-based radar astronomy. In stark contrast to quad-pol, compact polarimetry is compatible with wide swath modes of a SAR, including ScanSAR. All operational modes of the SARs aboard Canada’s three-satellite Radarsat Constellation Mission (RCM) are hybrid dual-polarimetric. Image classification methodologies for HCP data are reviewed, two of which introduce errors for reasons explained. Their use is discouraged. An alternative and recommended group of methodologies yields reliable results, illustrated by polarimetrically classified images. A survey over numerous quantitative studies demonstrates HCP polarimetric classification effectiveness. The results verify that the performance accuracy of the HCP architecture is comparable to the accuracy delivered by a quadrature-polarized SAR. Four appendices are included covering related topics, including comments on inflight calibration of an HCP radar. Full article
(This article belongs to the Special Issue Compact Polarimetric SAR)
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16 pages, 979 KiB  
Article
Quantum Fisher Information and Entanglement of Moving Two Two-Level Atoms under the Influence of Environmental Effects
by Syed Jamal Anwar, M. Usman, M. Ramzan and M. Khalid Khan
Physics 2019, 1(1), 131-146; https://doi.org/10.3390/physics1010013 - 5 Jun 2019
Cited by 1 | Viewed by 4570
Abstract
We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) of a two moving two-level atomic systems interacting with a coherent and thermal field in the presence of intrinsic decoherence (ID) and Kerr (non-linear medium) and Stark effects. [...] Read more.
We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) of a two moving two-level atomic systems interacting with a coherent and thermal field in the presence of intrinsic decoherence (ID) and Kerr (non-linear medium) and Stark effects. The state of the entire system interacting with coherent and thermal fields is evaluated numerically under the influence of ID and Kerr (nonlinear) and Stark effects. QFI and von Neumann entropy (VNE) decrease in the presence of ID when the atomic motion is neglected. QFI and QE show an opposite response during its time evolution in the presence of a thermal environment. QFI is found to be more susceptible to ID as compared to QE in the presence of a thermal environment. The decay of QE is further damped at greater time-scales, which confirms the fact that ID heavily influences the system’s dynamics in a thermal environment. However, a periodic behavior of entanglement is observed due to atomic motion, which becomes modest under environmental effects. It is found that a non-linear Kerr medium has a prominent effect on the VNE but not on the QFI. Furthermore, it has been observed that QFI and QE decay soon under the influence of the Stark effect in the absence of atomic motion. The periodic response of QFI and VNE is observed for both the non-linear Kerr medium and the Stark effect in the presence of atomic motion. It is observed that the Stark, Kerr, ID, and thermal environment have significant effects during the time evolution of the quantum system. Full article
(This article belongs to the Section Atomic Physics)
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14 pages, 1160 KiB  
Article
Entanglement Dynamics of Three and Four Level Atomic System under Stark Effect and Kerr-Like Medium
by S. Jamal Anwar, M. Ramzan, M. Usman and M. Khalid Khan
Quantum Rep. 2019, 1(1), 23-36; https://doi.org/10.3390/quantum1010004 - 28 May 2019
Cited by 14 | Viewed by 3531
Abstract
We investigated numerically the dynamics of quantum Fisher information (QFI) and entanglement for three- and four-level atomic systems interacting with a coherent field under the effect of Stark shift and Kerr medium. It was observed that the Stark shift and Kerr-like medium play [...] Read more.
We investigated numerically the dynamics of quantum Fisher information (QFI) and entanglement for three- and four-level atomic systems interacting with a coherent field under the effect of Stark shift and Kerr medium. It was observed that the Stark shift and Kerr-like medium play a prominent role during the time evolution of the quantum systems. The non-linear Kerr medium has a stronger effect on the dynamics of QFI as compared to the quantum entanglement (QE). QFI is heavily suppressed by increasing the value of Kerr parameter. This behavior was found comparable in the cases of three- and four-level atomic systems coupled with a non-linear Kerr medium. However, QFI and quantum entanglement (QE) maintain their periodic nature under atomic motion. On the other hand, the local maximum value of QFI and von Neumann entropy (VNE) decrease gradually under the Stark effect. Moreover, no prominent difference in the behavior of QFI and QE was observed for three- and four-level atoms while increasing the value of Stark parameter. However, three- and four-level atomic systems were found equally prone to the non-linear Kerr medium and Stark effect. Furthermore, three- and four-level atomic systems were found fully prone to the Kerr-like medium and Stark effect. Full article
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16 pages, 1762 KiB  
Article
An Ab Initio QM/MM Study of the Electrostatic Contribution to Catalysis in the Active Site of Ketosteroid Isomerase
by Xianwei Wang and Xiao He
Molecules 2018, 23(10), 2410; https://doi.org/10.3390/molecules23102410 - 20 Sep 2018
Cited by 14 | Viewed by 4019
Abstract
The electric field in the hydrogen-bond network of the active site of ketosteroid isomerase (KSI) has been experimentally measured using vibrational Stark effect (VSE) spectroscopy, and utilized to study the electrostatic contribution to catalysis. A large gap was found in the electric field [...] Read more.
The electric field in the hydrogen-bond network of the active site of ketosteroid isomerase (KSI) has been experimentally measured using vibrational Stark effect (VSE) spectroscopy, and utilized to study the electrostatic contribution to catalysis. A large gap was found in the electric field between the computational simulation based on the Amber force field and the experimental measurement. In this work, quantum mechanical (QM) calculations of the electric field were performed using an ab initio QM/MM molecular dynamics (MD) simulation and electrostatically embedded generalized molecular fractionation with conjugate caps (EE-GMFCC) method. Our results demonstrate that the QM-derived electric field based on the snapshots from QM/MM MD simulation could give quantitative agreement with the experiment. The accurate calculation of the electric field inside the protein requires both the rigorous sampling of configurations, and a QM description of the electrostatic field. Based on the direct QM calculation of the electric field, we theoretically confirmed that there is a linear correlation relationship between the activation free energy and the electric field in the active site of wild-type KSI and its mutants (namely, D103N, Y16S, and D103L). Our study presents a computational protocol for the accurate simulation of the electric field in the active site of the protein, and provides a theoretical foundation that supports the link between electric fields and enzyme catalysis. Full article
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28 pages, 1542 KiB  
Review
Beyond the Linear Stark Effect: A Retrospective
by Alexander V. Demura
Atoms 2018, 6(2), 33; https://doi.org/10.3390/atoms6020033 - 6 Jun 2018
Cited by 16 | Viewed by 4150
Abstract
A review of studies of the electric-field influence on spectral lines is presented, beginning from the discovery of the Stark effect, and in particular focused on phenomena related to the effects of the plasma microfield non-uniformity. Full article
(This article belongs to the Special Issue Spectral Line Shapes in Plasmas II)
16 pages, 1874 KiB  
Article
The Evaluation on the Cadmium Net Concentration for Soil Ecosystems
by Yu Yao, Pei-Fang Wang, Chao Wang, Jun Hou and Ling-Zhan Miao
Int. J. Environ. Res. Public Health 2017, 14(3), 297; https://doi.org/10.3390/ijerph14030297 - 12 Mar 2017
Cited by 9 | Viewed by 4701
Abstract
Yixing, known as the “City of Ceramics”, is facing a new dilemma: a raw material crisis. Cadmium (Cd) exists in extremely high concentrations in soil due to the considerable input of industrial wastewater into the soil ecosystem. The in situ technique of diffusive [...] Read more.
Yixing, known as the “City of Ceramics”, is facing a new dilemma: a raw material crisis. Cadmium (Cd) exists in extremely high concentrations in soil due to the considerable input of industrial wastewater into the soil ecosystem. The in situ technique of diffusive gradients in thin film (DGT), the ex situ static equilibrium approach (HAc, EDTA and CaCl2), and the dissolved concentration in soil solution, as well as microwave digestion, were applied to predict the Cd bioavailability of soil, aiming to provide a robust and accurate method for Cd bioavailability evaluation in Yixing. Moreover, the typical local cash crops—paddy and zizania aquatica—were selected for Cd accumulation, aiming to select the ideal plants with tolerance to the soil Cd contamination. The results indicated that the biomasses of the two applied plants were sufficiently sensitive to reflect the stark regional differences of different sampling sites. The zizania aquatica could effectively reduce the total Cd concentration, as indicated by the high accumulation coefficients. However, the fact that the zizania aquatica has extremely high transfer coefficients, and its stem, as the edible part, might accumulate large amounts of Cd, led to the conclusion that zizania aquatica was not an ideal cash crop in Yixing. Furthermore, the labile Cd concentrations which were obtained by the DGT technique and dissolved in the soil solution showed a significant correlation with the Cd concentrations of the biota accumulation. However, the ex situ methods and the microwave digestion-obtained Cd concentrations showed a poor correlation with the accumulated Cd concentration in plant tissue. Correspondingly, the multiple linear regression models were built for fundamental analysis of the performance of different methods available for Cd bioavailability evaluation. The correlation coefficients of DGT obtained by the improved multiple linear regression model have not significantly improved compared to the coefficients obtained by the simple linear regression model. The results revealed that DGT was a robust measurement, which could obtain the labile Cd concentrations independent of the physicochemical features’ variation in the soil ecosystem. Consequently, these findings provide stronger evidence that DGT is an effective and ideal tool for labile Cd evaluation in Yixing. Full article
(This article belongs to the Section Environmental Health)
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17 pages, 580 KiB  
Article
Vibrational Stark Effect of the Electric-Field Reporter 4-Mercaptobenzonitrile as a Tool for Investigating Electrostatics at Electrode/SAM/Solution Interfaces
by Gal Schkolnik, Johannes Salewski, Diego Millo, Ingo Zebger, Stefan Franzen and Peter Hildebrandt
Int. J. Mol. Sci. 2012, 13(6), 7466-7482; https://doi.org/10.3390/ijms13067466 - 18 Jun 2012
Cited by 65 | Viewed by 11415
Abstract
4-mercaptobenzonitrile (MBN) in self-assembled monolayers (SAMs) on Au and Ag electrodes was studied by surface enhanced infrared absorption and Raman spectroscopy, to correlate the nitrile stretching frequency with the local electric field exploiting the vibrational Stark effect (VSE). Using MBN SAMs in different [...] Read more.
4-mercaptobenzonitrile (MBN) in self-assembled monolayers (SAMs) on Au and Ag electrodes was studied by surface enhanced infrared absorption and Raman spectroscopy, to correlate the nitrile stretching frequency with the local electric field exploiting the vibrational Stark effect (VSE). Using MBN SAMs in different metal/SAM interfaces, we sorted out the main factors controlling the nitrile stretching frequency, which comprise, in addition to external electric fields, the metal-MBN bond, the surface potential, and hydrogen bond interactions. On the basis of the linear relationships between the nitrile stretching and the electrode potential, an electrostatic description of the interfacial potential distribution is presented that allows for determining the electric field strengths on the SAM surface, as well as the effective potential of zero-charge of the SAM-coated metal. Comparing this latter quantity with calculated values derived from literature data, we note a very good agreement for Au/MBN but distinct deviations for Ag/MBN which may reflect either the approximations and simplifications of the model or the uncertainty in reported structural parameters for Ag/MBN. The present electrostatic model consistently explains the electric field strengths for MBN SAMs on Ag and Au as well as for thiophenol and mercaptohexanoic acid SAMs with MBN incorporated as a VSE reporter. Full article
(This article belongs to the Special Issue Self-Assembled Soft Matter Nanostructures at Interfaces)
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