Unraveling preference heterogeneity in willingness-to-pay for enhanced road safety: A hybrid approach of machine learning and quantile regression.

Investing in road safety enhancement programs highly depends on the economic valuation of road traffic accidents and their outcomes. Such evaluation underpins road safety interventions in cost-benefit analysis. To this end, understanding and modeling public willingness-to-pay for enhanced road safety have received significant attention in the past few decades. However, despite considerable modeling efforts, some issues still persist in earlier studies, namely, (i) using standard regression approaches that assume a homogeneous impact of explanatory variables on willingness-to-pay, not accounting for heterogeneity, and depends on a priori distribution of the dependent variable, and (ii) the absence of higher-order interactions from models, leading to omitted variable bias and erroneous model inferences. To overcome this critical research gap, our study proposes a new modeling framework, integrating a machine learning technique (decision tree) to identify a priori relationships for higher-order interactions and a quantile regression model to account for heterogeneity along the entire range of willingness-to-pay. The proposed framework examines the determinants of willingness-to-pay for enhanced road safety using a sample of car drivers from Peshawar, Pakistan. Modeling results indicate that variables not significant in a linear model become significant at specific quantiles of the willingness-to-pay distribution. Further, including higher-order interactions among the explanatory variables provides additional insights into the complex relationship between willingness-to-pay and its determinants. In addition, willingness-to-pay for fatal and severe injury risk reductions is estimated at different quartiles and used to calculate the values of corresponding risk reductions. Overall, the proposed framework provides a better understanding of public sensitivities to willingness-to-pay for enhanced road safety.

Evaluating groundwater nitrate and other physicochemical parameters of the arid and semi-arid district of DI Khan by multivariate statistical analysis.

Nitrate as an important water pollutant, causing eutrophication was analyzed in Pakistan at different water sources (hand pump (HP), bore hole (BH) and tube well (TW)) to assess the contamination level caused by NO3-. NO3- concentrations in the HP water samples were 31 mg L-1 to 59 mg L-1, in BH 20 mg L-1 to 79 mg L-1 while in TW water samples it was between 29 to 55 mg L-1. The association of NO3- with other selected parameter in groundwater can be determined by using statistical approaches. Different physicochemical parameters (pH, electrical conductivity (EC), temperature and dissolved oxygen (DO)) were studied in groundwater samples of the research district. The Pearson correlation coefficient (r) for groundwater characteristics were calculated. Hierarchical Cluster Analysis (HCA) was used to categorize samples based on their groundwater quality similarities and to find links between groundwater quality factors. The key relationship of the groundwater for HP samples on EC and TDS (r = 1) had a great correlation, while all other parameters correlations were lower (r = 0.40), BH's parameters on WT and WSD (r = 0.57), WT and pH (r = 0.57), EC and DO (r = 0.50), DO and TDS (0.50), EC and TDS (r = 1) had a quite high correlation, while all other parameters correlations were less than (r = 0.40), on the other hand, tube well parameters on TDS and EC (r = 1) had a perfect correlation, DO and pH (r = 0.75) parameters correlations were less than (r = 0.40).

Exfoliation of MoS2 Quantum Dots: Recent Progress and Challenges.

Although, quantum dots (QDs) of two-dimensional (2D) molybdenum disulfide (MoS2) have shown great potential for various applications, such as sensing, catalysis, energy storage, and electronics. However, the lack of a simple, scalable, and inexpensive fabrication method for QDs is still a challenge. To overcome this challenge, a lot of attention has been given to the fabrication of QDs, and several fabrication strategies have been established. These exfoliation processes are mainly divided into two categories, the 'top-down' and 'bottom-up' methods. In this review, we have discussed different top-down exfoliation methods used for the fabrication of MoS2 QDs and the advantages and limitations of these methods. A detailed description of the various properties of QDs is also presented.

Public intention to pay for road safety improvement: A case study of Pakistan.

The dramatic increase in road traffic accidents poses social and economic challenges to nations, especially for developing countries. Thus, road safety urgently needs to be significantly improved at the national level to reduce the number of road traffic accidents and costs associated with it. Understanding road users' acceptance of road pricing regarding road safety improvement is crucial for safety-related investment programs. As such, this paper investigated the factors associated with public intention-to-pay (ITP) for road safety improvement in Pakistan. A structural equation model (SEM) was adopted to analyze the determinants of ITP according to the theory of planned behavior (TPB) combined with latent psychological variables that describe the personal characteristics and evaluations of different measures. Furthermore, the moderating effects of socioeconomic characteristics were also examined. A sample of 340 car drivers, interviewed at different locations of Peshawar, Pakistan, was used to test the model. Results of the SEM model indicated that Road Infrastructure Safety Perception and Perceived Behavioral Control have strong association with the ITP of car users' for road safety improvement. Risk Perception, Attitude towards Traffic Safety Responsibility, Attitude, Perceived Fairness, and Perceived Effectiveness were also associated with ITP. Differential age and gender-related moderating effects were also observed. Findings from this study are expected to assist the decision-makers in the effective planning and implementation of road safety projects and related budget allocations.

Assessing the physico-chemical parameters and some metals of underground water and associated soil in the arid and semiarid regions of Tank District, Khyber Pakhtunkhwa, Pakistan.

Good-quality water and food are the basic needs of humans, plants, and animals. Polluted groundwater and soil directly and indirectly affect organisms, which is the main environmental concern. In the current study, standard protocols of atomic absorption spectrometry were adopted for the investigation of selected metals (lead, chromium, and iron) in the collected groundwater and soil samples. The Pearson correlation coefficient (r) applied to groundwater and soil samples shows a positive perfect correlation among water parameters (conductivity and total dissolved solids) in all three sources. In the hand pump samples between water table (WT) and water source depth (WSD), Pearson correlation coefficient (r) value was found (r = 0.87) while between EC and TDS, it was r = 1. Similarly, in the bore hole samples between WT and WSD (r = 0.66), EC and TDS (r = 1), EC and Cr (r = 0.70), and TDS and Cr (r = 0.70), which showed weaker correlation. In the tube well samples, correlation between EC and TDS was high (r = 1). The correlation coefficient (r) values of the soil parameters in the hand pump (soil) samples between Fe and Cr (r = 0.86), in bore hole samples between Fe and Cr (r = 0.77), in tube well samples between Fe and Cr (r = 0.69), while all the other parameter correlations were found lower (r = 0.60). Between electrical conductivity and total dissolved solids, high relation has been observed between them (r = 1). Overall, results showed that in most of the studied samples, contents of the target metals were found above the allowable limit set by the World Health Organization (WHO) and the United States Environmental Protection Agency (USEPA).

Highly dispersive palladium nanoparticle in nanoconfined spaces for heterogeneous catalytic reduction of anthropogenic pollutants.

Pd-containing catalysts are highly promising in catalytic reactions, and their activity severely dependent on the dispersion extent of Pd nanoparticles (Pd NPs) . However, the regulation of Pd NPs size and dispersion degree are now pretty much the agendas. Here we report a facile solid-state fabrication strategy (SSFS) to promote Pd NPs dispersion in the nano environment of as made mesoporous silica KIT-6 (AK) by taking advantage of three critical factors, namely (i) the confined spaces where Pd precursor locate during fabrication, (ii) the interaction between Pd and supports, and (iii) the 3-dimentional (3D) structure of AK. First, AK presents 3D confined spaces between silica walls and template P123. Second, both silica walls and template P123 in AK offer interaction with Pd precursor. Third, the 3D structure provides more easy access for Pd insertion than linear channels structure without any pore blockage. The characterization results revealed that AK give better dispersion with smaller size of (3.9 nm) Pd than its counterpart (16 nm) prepared from template-free KIT-6 (CK). Moreover, the synthesized catalysts exhibit excellent activity and stability in catalytic conversion of p-nitrophenol (p-NP) and Methylene blue (MB). For a typical PdAK-1.0 catalyst, the complete conversion of P-NP and MB was achieved in less than 10 min with a reaction rate constant (k) of 0.3106 and 0.345 min-1, respectively. It is superior to that on PdCK-1.0 prepared from template free KIT-6 and several reported catalysts. Furthermore, the PdAK-1.0 catalyst presents pretty good stability in catalytic reduction and is apparently better than PdCK-1.0.

Unusual Pd nanoparticle dispersion in microenvironment for p-nitrophenol and methylene blue catalytic reduction.

Palladium based catalysts are highly attractive for catalytic reactions. However, the catalytic activity is dependent on the dispersion and size of Pd nanoparticles (NPs). Herein, an efficient strategy is developed to regulate the size and dispersion of Pd NPs in nanoconfined spaces provided by Santa Barbara Amorphous-15 (SBA-15) occluded with template. The Pd precursor is introduced to the confined spaces between the template and silica walls in as-synthesized SBA-15 (AS) by grinding. Subsequent reduction allow template removal and precursor conversion to Pd0 in single step and avoids aggregation that take place in calcined SBA-15 (CS). Our results show that up to 1.0 wt% of Pd can be well dispersed in confined spaces of AS (denoted as 1.0PdAS), while sever aggregation take place from CS with the same Pd loading (denoted as1.0PdCS). We also demonstrated that 1.0PdAS is highly efficient for catalytic reduction of p-nitrophenol (P-NP) and Methylene blue (MB) with rate constant of 0.4924 and 0.626 min-1, respectively, which is superior than 1.0PdCS attributed to well dispersed and smaller size (3 nm) Pd NPs. Furthermore, no change in the rate constant of P-NP (0.4924 min-1) and MB (0.626 min-1) after regeneration presents good stability of 1.0PdAS in catalytic reactions.

Magnetic anisotropy and Curie temperature of two-dimensional VI3 monolayer.

Recently, it was reported that the VI3 had a Mott insulator nature and also displayed the structural and magnetic phase transition at low temperature. Here, we explored the magnetic properties of the two-dimensional (2D) monolayer structure using the density functional theory. We found that the 2D VI3 had an enhanced lattice constant compared with that in the bulk structure. Besides, the 2D monolayer had an indirect band gap of 0.98 eV, and this band gap was increased (decreased) with tensile (compressive) strain up to ±3%. The monolayer structure had a ferromagnetic ground state and this nature was preserved under both tensile and compressive strains. We obtained that the monolayer structure had a perpendicular magnetic anisotropy energy of 0.29 meV/cell. The perpendicular magnetic anisotropy still remained even after applying the tensile and compressive strains although the magnitude of magnetic anisotropy was slightly changed. Using the Metropolis Monte Carlo simulations, we found that the monolayer had a Curie temperature of 46 K. This Curie temperature was increased to 57 K with 3% tensile strain whereas it was decreased to 35 K with 3% compressive strain. Overall, we found that the magnetic property of 2D VI3 monolayer was robust under the strain.

Two-dimensional graphitic carbon nitride (g-C4N3) for superior selectivity of multiple toxic gases (CO, NO2, and NH3).

Using first principles calculations, we investigated the possibility of selecting multiple toxic gases using one substrate material. Here, we explored the transport property of H2, N2, O2, CO, CO2, NO2, and NH3 gas molecules on two-dimensional graphitic carbon nitride (2D g-C4N3). The homonuclear molecule such as H2, N2, and O2 has very weak adsorption energy (equal to or less than 0.1 eV) and also CO2 has an adsorption energy of 0.23 eV. In the typical toxic gas molecule adsorption systems, we found an appreciable charge transfer. In CO and NH3 adsorption systems, the charge transfer of 0.397 and 0.418 electrons from the molecule to the substrate was found, while the NO2 molecule gained 0.124 electrons from the substrate. Due to this large amount of charge transfer, we obtained large adsorption energies of 4.57, 1.29, and 1.93 eV in CO, NO2, and NH3 systems. Moreover, through the I-V curve calculations, we found large difference in the current. The calculated current was 21, 13.11, and 16.16 µA for CO, NO2, and NH3 systems at the bias voltage of 0.5 V. Our results imply that the 2D g-C4N3 can be a superior substrate material for sensing of multiple toxic gases.

Pressure-induced ferromagnetism and enhanced perpendicular magnetic anisotropy of bilayer CrI3.

Using the first principles calculations, we explored the pressure dependent magnetic properties of CrI3 bilayer for AB and AA type stacking. We found an anti-ferromagnetic (AFM) ground state in both pristine bilayer systems with indirect band gaps of 1.71 and 1.68 eV for AB and AA type system. However, the transition from AFM to ferromagnetic (FM) state was achieved with the pressure and the band gap was decreased although the indirect band gap nature remains unchanged. We obtained a substantially enhanced perpendicular magnetic anisotropy with pressure. In the pristine AFM bilayer, both Cr and iodine atoms almost equally contributed to the perpendicular magnetic anisotropy. However, the contribution from the iodine atoms was almost four times larger than the Cr contribution with increasing the pressure. Particularly, the interface iodine atoms played a major role for the enhancement of the perpendicular magnetic anisotropy. We found that both AB and AA type bilayer displayed the same tendency.

Fabrication of 3-D confined spaces with Au NPs: Superior dispersion and catalytic activity.

Gold nanoparticles (Au NPs) as an active noble-metal site have received great attention because of its superior catalytic activity in diverse reactions. However, the activity of Au NPs is strongly dependent on its size and dispersion degree. Therefore, we developed an efficient solid-state reduction (SSR) strategy for the first time to promote the dispersion degree and size of Au NPs in template-occluded KIT-6 (AK) as a support by taking advantage of (i) 3-dimentonal cubic mesoporous structure of support (ii) confined spaces present between template (Pluronic (P) 123) and silica wall of AK where Au NPs locate (iii) interaction of both P123 as template and silica walls of AK with Au NPs highly efficient for Au NPs dispersion and (iv) SSR strategy which avoids competitive adsorption of solvent in the conventional fabrication process. The results revealed that Au-based AK (AuAK) has much better dispersion of Au NPs with smaller sizes than template-free KIT-6 (CK). Moreover, the catalytic activity of AuAK in reduction reactions of p-nitrophenol (P-NP) to p-aminophenol (P-AP) and Methylene blue (MB) to Leuco MB (LMB) is superior than AuCK as well as to those Au-catalysts synthesized via conventional strategies previously. The catalytic performance is also related well with characterization results.

Bias-dependent transport properties of passivated tilted black phosphorene nanoribbons.

Using the density functional theory incorporated with a non-equilibrium Green's function (NEGF) technique, we explored the bias-dependent transport of tilted phosphorene nanoribbons. Herein, we considered three types of nanoribbons: self-passivated (TPNRself), H-passivated (TPNRH), and O-passivated (TPNRO) systems. The TPNRself showed an indirect band gap of 0.53 eV, whereas the TPNRH displayed a direct band gap of 1.32 eV. In TPNRO, we observed a spin-polarized band structure with a spin-dependent band gap. We found that the bias-dependent I-V curve was dependent on the passivation effect. In TPNRself and TPNRH, the current monotonically increased with an external bias, but the magnitude of the current in TPNRself was more than 10 times than that in TPNRself. Unlike the I-V characteristics in TPNRself and TPNRH, the current in TPNRO almost vanished beyond an external bias of 1.7 V. Mostly, the bias-dependent I-V was interpreted based on the band structure in the lead parts. However, we found that this conventional approach was not sufficient to analyze the I-V curve. Indeed, we showed that the detailed I-V curve could be understood by calculating the bias-dependent density of states in the scattering part related to the transmission channel. It was also found that the electron flow channel was dependent on the passivation effect and uniformly distributed over the entire nanoribbon in TPNRself and TPNRH. In contrast, the electron flowed mostly along the edge line in TPNRO. Moreover, we have found that spin polarization in the conduction current can be manipulated by an external bias, and this may suggest that the TPNRO can be utilized for potential spintronic applications.

Effects of alkali-treated agricultural residues on nitrate removal and N2O reduction of denitrification in unsaturated soil.

Lignocellulosic agricultural residues were utilized as denitrification carbon substrates to improve the purification capacity of unsaturated soil and alleviate nitrate pollution of groundwater. In this study, corncob and wheat straw were treated by calcium hydroxide to improve biodegradability and enhance denitrification potential. Calcium hydroxide treatment decreased the contents of lignin (i.e., from 16.7 wt% to 15.2 wt% in corncob and from 21.9 wt% to 20.6 wt% in wheat straw), increased potential biodegradable carbon by 4.4-5.3 times, reached complete nitrate removal 7-14 days earlier and decreased N2O/(N2O+N2) ratios by 85-99%. The results provide an insight into the application of alkali-treated agricultural residues as denitrification carbon sources to alleviate nitrate transport to groundwater and reduce potential greenhouse effect.

In situ one-step synthesis of Fe3O4@MIL-100(Fe) core-shells for adsorption of methylene blue from water.

A new route for Fe3O4@MIL-100(Fe) core-shells is proposed via in situ one-step hydrothermal strategy, in which Fe3O4 microspheres not only serve as magnetic cores but also provide Fe(III) for MIL-100(Fe) synthesis. The MIL-100(Fe) is uniformly grown as a shell on the surface of Fe3O4, and the shell thickness can be fine-tuned from 73.5 to 148nm by simply controlling the reaction time. Compared with Fe3O4, the surface area and pore volume of the Fe3O4@MIL-100(Fe) are significantly increased while the magnetism is barely affected. The application of Fe3O4@MIL-100(Fe) in adsorption was tested using several dyes as model analytes, and showed high adsorption capacity (221mgg-1) towards methylene blue (MB), which is based on electrostatic interactions and size filter effect. The MB adsorption isotherm follows Langmuir model and pseudo second-order kinetic model. Intra-particle diffusion model reveals that both film and pore diffusions are involved in the rate limiting steps. The adsorption is controlled by enthalpy change rather than entropy effect. ΔH, ΔS and ΔG values indicated that the adsorption process was spontaneous and exothermic. Simple synthesis procedure, immense magnetism, high adsorption capacity and excellent reusability of Fe3O4@MIL-100(Fe) make it an attractive candidate for application of MB removal from polluted environmental samples.

Determination of amphetamines in biological samples using electro enhanced solid-phase microextraction-gas chromatography.

In this work, an ordered mesoporous carbon (OMC)/Nafion coated fiber for solid-phase microextraction (SPME) was prepared and used as the working electrode for electro-enhanced SPME (EE-SPME) of amphetamines. The EE-SPME strategy is primarily based on the electro-migration and complementary charge interaction between fiber coating and ionic compounds. Compared with traditional SPME, EE-SPME exhibited excellent extraction efficiency for amphetamine (AP) and methamphetamine (MA) with an enhancement factor of 7.8 and 12.1, respectively. The present strategy exhibited good linearity for the determination of AP and MA in urine samples in the range of 10-1000ngmL(-1) and 20-1000ngmL(-1), respectively. The detection limits were found to be 1.2ngmL(-1) for AP and 4.8ngmL(-1) for MA. The relative standard deviations were calculated to be 6.2% and 8.5% for AP and MA, respectively. Moreover, the practical application of the proposed method was demonstrated by analyzing the amphetamines in urine and serum samples with satisfactory results.

Protective Role of G6PD Deficiency in Aluminium Phosphide Poisoning.

A 15-year-old boy was referred to the hospital from the periphery with a history of ingestion of 5 wheat pills (aluminium phosphide) 5 days back. He had been given a stomach wash in his village hospital prior to referral. On arrival, he was jaundiced and had developed haematuria too, but otherwise appeared well in himself. Four days after admission, his haemoglobin showed a marked drop and he was shifted to intensive care, keeping in mind the high mortality rate associated with aluminium phosphide intoxication. His G6PD levels were checked, and he turned out to be G6PD deficient. The patient was given intravenous magnesium sulphate and supportive care and he improved subsequently. Wheat pill poisoning carries a high mortality of 98% in some cases; despite the high mortality, this patient survived. This may mean that G6PD deficiency has a protective role in poisoning due to aluminium phosphide.

A simple, rapid and eco-friendly approach for the analysis of aromatic amines in environmental water using single-drop microextraction-gas chromatography.

Single-drop microextraction (SDME) coupled with gas chromatography-flame ionization detector (GC-FID) was developed for the extraction and determination of aromatic amines (AAs) in environmental water samples. A silicon tube was introduced for the SDME procedure by inserting it into the needle of the micro-injector. In this manner, a large volume of extractant is allowed to be suspended for the extraction, leading to the enhancement of method sensitivity and reproducibility. Extraction parameters which control the performance of SDME such as the type of microextraction solvent and volume, sample pH, ionic strength and extraction time were investigated and optimized. Under the optimized conditions, the SDME-GC method exhibited good linearity from 0.5 to 50 µg mL(-1) for aniline and 4-methylaniline and 0.1 to 50 µg mL(-1) for N-methylaniline and N, N-diethylaniline. The enrichment factors were calculated to be 42-509. The SDME-GC method was performed for the determination of AAs in environmental water samples including drinking, lake and sea water, and excellent recoveries and relative standard deviations (RSD values) ranging from 79.5 to 122.7% and 3.2 to 13.3%, respectively, were obtained. The results demonstrated that SDME-GC is a rapid, simple and effective sample preparation method and could be successfully applied for the determination of AAs in environmental water samples.

Ordered mesoporous carbon/Nafion as a versatile and selective solid-phase microextraction coating.

In this study, ordered mesoporous carbon (OMC) with large surface area (1019m(2)g(-1)), uniform mesoporous structure (pore size distribution centering at 4.2nm) and large pore volume (1.46cm(3)g(-1)) was synthesized using 2D hexagonally mesoporous silica MSU-H as the hard template and sucrose as the carbon precursor. The as-synthesized OMC was immobilized onto a stainless steel wire using Nafion as a binder to prepare an OMC/Nafion solid-phase microextraction (SPME) coating. The extraction characteristics of the OMC/Nafion coating were extensively investigated using a wide range of analytes including non-polar (light petroleum and benzene homologues) and polar compounds (amines and phenols). The OMC/Nafion coating exhibited much better extraction efficiency towards all selected analytes than that of a multi-walled carbon nanotubes/Nafion coating with similar length and thickness, which is ascribed to its high surface area, well-ordered mesoporous structure and large pore volume. When the OMC/Nafion coating was used to extract a mixture containing various kinds of analytes, it possessed excellent extraction selectivity towards aromatic non-polar compounds. In addition, the feasibility of the OMC/Nafion coating for application in electrochemically enhanced SPME was demonstrated using protonated amines as model analytes.

The enhanced adsorption of sulfur compounds onto mesoporous Ni-AlKIT-6 sorbent, equilibrium and kinetic analysis.

High performance nickel supported on mesoporous AlKIT-6 (Si/Al=15, 25, 50, 100) sorbents were prepared by incipient wetness impregnation (IWI) with ultrasonic aid for adsorptive desulfurization of commercial diesel and simulated fuels. The sorbents were characterized by N2 adsorption-desorption, XRD, NH3-TPD, Py-FT-IR, HRTEM, SEM and atomic absorption spectroscopy techniques. The analysis results confirmed that Aluminum atoms entered the framework and 20%Ni-AlKIT-6(15) can still retain three dimensional structure of AlKIT-6(15) and Ni is highly dispersed in the support. The kinetic pseudo second-order model and Langmuir isotherm are shown to exhibits the best fits of experimental data for the adsorption of thiophene (T), benzothiophene (BT) and dibenzothiophene (DBT) over AlKIT-6 and 5-30%Ni-AlKIT-6. Intraparticle diffusion and steric hindrance were the rate controlling step of the adsorption of T and DBT over AlKIT-6(15) and 20%Ni-AlKIT-6(15) as verified through the intraparticle diffusion model. The characterization of regenerated 20%Ni-AlKIT-6(15) revealed that three-dimensional cubic Ia3d symmetric structure was maintained in the sorbent after 6 successive desulfurization-regeneration cycles.

The fabrication of porous N-doped carbon from widely available urea formaldehyde resin for carbon dioxide adsorption.

N-doped carbon material constitutes abundant of micropores and basic nitrogen species that have potential implementation for CO2 capture. In this paper, porous carbon material with high nitrogen content was simply fabricated by carbonizing low cost and widely available urea formaldehyde resin, and then followed by KOH activation. CO2 capture experiment showed high adsorption capacity of 3.21 mmol g(-1) at 25 °C under 1 atm for UFCA-2-600. XRD, SEM, XPS and FT-IR analysis confirmed that a graphitic-like structure was retained even after high temperature carbonization and strong base activation. Textural property analysis revealed that narrow micropores, especially below 0.8 nm, were effective for CO2 adsorption by physical adsorption mechanism. Chemical evolved investigation revealed that graphitic-like embedded basic nitrogen groups are generated from bridged and terminal amines of urea formaldehyde resin from thermal carbonization and KOH activation treatment, which is responsible for the enrichment of CO2 capacity by chemical adsorption mechanism. The relationship between CO2 adsorption capacity and pore size or basic N species was also studied, which turned out that both of them played crucial role by physical and chemical adsorption mechanism, respectively.