Martini-Based Coarse-Grained Soil Organic Matter Model Derived from Atomistic Simulations.

The significance of soil organic matter (SOM) in environmental contexts, particularly its role in pollutant adsorption, has prompted an increased utilization of molecular simulations to understand microscopic interactions. This study introduces a coarse-grained SOM model, parametrized within the framework of the versatile Martini 3 force field. Utilizing models generated by the Vienna Soil Organic Matter Modeler 2, which constructs humic substance systems from a fragment database, we employed Swarm-CG to parametrize the fragments and subsequently assembled them into macromolecules. Direct Boltzmann inversion (DBI) facilitated the determination of bonded parameters between fragments. The parametrization yielded favorable agreement in the radius of gyration and solvent-accessible surface area. Transfer free energies exhibited a strong correlation with hexadecane-water and chloroform-water values, albeit deviations were noted for octanol-water values. Comparing densities of modeled Leonardite humic acid systems at coarse-grained and atomistic levels revealed promising agreement, particularly at higher water concentrations. The DBI approach effectively reproduced average values of bonded interactions between fragments. Radial distribution functions between carboxylate groups and calcium ions showed partial agreement, however, reproducing certain peaks was challenging due to fixed bead sizes. Detailed analysis of atomistic systems revealed different configurations between the groups, explaining discrepancies. The present contribution provides a comprehensive insight into the properties, strengths, and weaknesses of the coarse-grained SOM model, serving as a foundation for future investigations encompassing pollutant interactions and varied SOM compositions.

Deciphering competitive interactions: Phosphate and organic matter binding on goethite through experimental and theoretical insights.

The adsorption of phosphorus (P) onto active soil surfaces plays a pivotal role in immobilizing P, thereby influencing soil fertility and the filter function of soil to protect freshwater systems from eutrophication. Competitive anions, such as organic matter (OM), significantly affect the strength of this P-binding, eventually controlling P mobility and release, but surprisingly, these processes are insufficiently understood at the molecular level. In this study, we provide a molecular-level perspective on the influence of OM on P binding at the goethite-water interface using a combined experimental-theoretical approach. By examining the impact of citric acid (CIT) and histidine (HIS) on the adsorption of orthophosphate (OP), glycerol phosphate (GP), and inositol hexaphosphate (IHP) through adsorption experiments and molecular dynamics simulations, we address fundamental questions regarding P binding trends, OM interaction with the goethite surface, and the effect of OM on P adsorption. Our findings reveal the complex nature of P adsorption on goethite surfaces, where the specific OM, treatment conditions (covering the surface with OM or simultaneous co-adsorption), and initial concentrations collectively shape these interactions. P adsorption on goethite exhibits a binding strength increasing in the order of GP < OP < IHP. Crucially, this trend remains consistent across all adsorption experiments, regardless of the presence or absence of OM, CIT, or HIS, and irrespective of the specific treatment method. Notably, OP is particularly susceptible to inhibition by OM, while adsorption of GP depends on specific OM treatments. Despite being less sensitive to OM, IHP shows reduced adsorption, especially at higher initial P concentrations. Of significance is the strong inhibitory effect of CIT, particularly evident when the surface is pre-covered, resulting in a substantial 70 % reduction in OP adsorption compared to bare goethite. The sequence of goethite binding affinity to P and OM underscores a higher affinity of CIT and HIS compared to OP and GP, suggesting that OM can effectively compete with both OP and GP and replace them at the surface. In contrast, the impact of OM on IHP adsorption appears insignificant, as IHP exhibits a higher affinity than both CIT and HIS towards the goethite surface. The coverage of goethite surfaces with OM results in the blocking of active sites and the generation of an unfavorable electric potential and field, inhibiting anion adsorption and consequently reducing P binding. It is noteworthy that electrostatic interactions predominantly contribute more to the binding of P and OM to the surface compared to dispersion interactions.

Discovery of dual-target natural antimalarial agents against DHODH and PMT of Plasmodium falciparum: pharmacophore modelling, molecular docking, quantum mechanics, and molecular dynamics simulations.

Malaria is a lethal disease that claims thousands of lives worldwide annually. The objective of this study was to identify new natural compounds that can target two P. falciparum enzymes; P. falciparum Dihydroorotate dehydrogenase (PfDHODH) and P. falciparum phosphoethanolamine methyltransferase (PfPMT). To accomplish this, e-pharmacophore modelling and molecular docking were employed against PfDHODH. Following this, 1201 natural compounds with docking scores of ≤ -7 kcal/mol were docked into the active site of the second enzyme PMT. The top nine compounds were subjected to further investigation using MM-GBSA free binding energy calculations and ADME analysis. The results revealed favourable free binding energy values better than the references, as well as acceptable pharmacokinetic properties. Compounds ZINC000013377887, ZINC000015113777, and ZINC000085595753 were scrutinized to assess their interaction stability with the PfDHODH enzyme, and chemical stability reactivity using molecular dynamics (MD) simulation and density functional theory (DFT) calculations. These findings indicate that the three natural compounds are potential candidates for dual PfDHODH and PfPMT inhibitors for malaria treatment.

Recycled high-density polyethylene plastic reinforced with ilmenite as a sustainable radiation shielding material.

In this work, recycled high-density polyethylene plastic (r-HDPE) reinforced with ilmenite mineral (Ilm) in different ratios (0, 15, 30, and 45 wt%) as a sustainable and flexible radiation shielding material was manufactured using the melt blending method. XRD patterns and FTIR spectra demonstrated that the polymer composite sheets were successfully developed. The morphology and elemental composition were addressed using SEM images and EDX spectra. Moreover, the mechanical characteristics of the prepared sheets were also studied. The gamma-ray attenuation characteristics for established r-HDPE + x% Ilm composite sheets were theoretically computed between 0.015 and 15 MeV using Phy-X/PSD software. Also, the mass attenuation coefficients have been compared to their values by the WinXCOM program. It is also shown that the shielding performance of the r-HDPE + 45% Ilm composite sheet is significantly greater than that of r-HDPE. As a result, the ilmenite-incorporated recycled high-density polyethylene sheets are suited for medical and industrial radiation shielding applications.

Advances in understanding the phosphate binding to soil constituents: A Computational Chemistry perspective.

Phosphorus (P) is an indispensable element to all forms of life and its efficient use in fertilizers is one of the conditions for food security. The efficiency of P fertilizers is affected by P mobilization and P fixation, both depending on the P binding strength to soil constituents. This review provides an overview of the P binding to soil constituents, especially to P-fixing mineral surfaces and its investigation using state-of-the-art Computational Chemistry (CC). A particular focus will be on goethite (α-FeOOH), which is highly significant in the context of P fixation in soils, given its prevalence, high susceptibility to P, and wide distribution across both oxic and anoxic environments. First, a brief overview will be given on experimental efforts related to the P adsorption at mineral surfaces and the factors affecting this process. Here, we will discuss the process of P adsorption, with a focus on important factors that influence this process, such as pH, surface crystallinity and morphology, competing anions, and electrolyte solutions. We will also explore the various techniques used to study this process and investigate the resulting binding motifs. Next, a brief introduction into common CC methods, techniques, and applications is presented, highlighting the advantages and limitations of each approach. Then, a comprehensive discussion of a wide range of the most relevant computational studies related to the phosphate binding issue will be provided. This will be followed by the main part of this review which is focusing on a possible strategy to cope with the soil heterogeneity by breaking down the complexity of P behavior in soil into well-defined models that can be discussed in terms of particular key factors. Hence, different molecular model systems and molecular simulations are introduced to reveal the P binding to soil organic matter (SOM), metal ions, and mineral surfaces. Simulation results provided an in-depth understanding of the P binding problem and explained at a molecular level the effects of surface plane, binding motif, kind and valency of metal ions, SOM composition, water, pH, and redox potential on the P binding in soil. On this basis, an overall molecular picture of P binding in soil can be then obtained by combining results for the different models. Eventually, challenges and further modifications of the existing molecular modeling approaches are discussed, such as steps necessary to bridge the molecular with the mesoscale.

Stepwise redox changes alter the speciation and mobilization of phosphorus in hydromorphic soils.

Sustainable engineering and management of hydromorphic arable soils need deep knowledge about the redox-mediated interactions between nutrients and soil colloids. Consequently, we examined the redox-mediated interactions of P with metal oxides and organic carbon (OC) in toe-, mid-, and upper-slope arable soils under dynamic redox changes using geochemical (biogeochemical microcosm), spectroscopic (XANES), and molecular (quantum chemical calculations (QCC)) approaches. We controlled the redox potential (EH) in two directions i.e., 1) slowly oxidizing direction (SOD; EH increased from -286 to +564 mV); and 2) slowly reducing direction (SRD; EH decreased from +564 to -148 mV). In the SOD of all soils, P, Fe2+ and OC mobilized at EH ≤ 200 mV, due to the pH decrease from 7.2 to 4.1 and dissolution of Fe-oxyhydroxides/carbonates, as indicated by the decrease of Fe-P and Ca-P determined by P-K-edge-XANES. At EH > 200 mV, P immobilized due to the strong P binding with Fe3+ as suggested by QCC. In the SRD of mid-slope-soil, P immobilized with decreasing EH, due to pH increase and P retention by aromatic carbon and/or precipitation by carbonates, as supported by increase of organic-P and Ca-P. These findings help for management of P in arable soils.

Novel adsorbent based on carbon-modified zirconia/spinel ferrite nanostructures: Evaluation for the removal of cobalt and europium radionuclides from aqueous solutions.

Herein, a novel adsorbent based on carbon-modified zirconia/spinel ferrite (C@ ZrO2/Mn0.5Mg0.25Zn0.25Fe2O4) nanostructures were chemically prepared to remove 60Co and 152+154Eu radionuclides from liquid media using batch experiments. The XRD pattern confirms the successful preparation of the C@ZrO2/MnMgZnFe2O4 composite. Also, SEM and TEM images confirmed that the composite owns a heterogeneous morphology in the nanoscale range. The optical band gap value of Mn0.5Mg0.25Zn0.25Fe2O4, ZrO2, and the composite samples was 1.45, 2.38, and 1.54 eV, respectively. Many parameters have been studied as the effect of time, solution pH, and initial ion concentration. The kinetics models for the removal process of 152+154Eu and 60Co radionuclides were studied. The second-order kinetic equation could describe the sorption kinetics for both radionuclides. The Langmuir monolayer capacity for 60Co was 82.51 mg/g and for 152+154Eu was 136.98 mg/g. The thermodynamic parameters such as free energy ΔGo, the enthalpy ΔHo, and the entropy ΔSo were calculated. The results indicated that the sorption process has endothermic nature for both two radionuclides onto C@ZrO2/MnMgZnFe2O4 composite.

Influence of Ce3+ Substitution on Antimicrobial and Antibiofilm Properties of ZnCexFe2-xO4 Nanoparticles (X = 0.0, 0.02, 0.04, 0.06, and 0.08) Conjugated with Ebselen and Its Role Subsidised with γ-Radiation in Mitigating Human TNBC and Colorectal Adenocarcinoma Proliferation In Vitro.

Cancers are a major challenge to health worldwide. Spinel ferrites have attracted attention due to their broad theranostic applications. This study aimed at investigating the antimicrobial, antibiofilm, and anticancer activities of ebselen (Eb) and cerium-nanoparticles (Ce-NPs) in the form of ZnCexFe2-XO4 on human breast and colon cancer cell lines. Bioassays of the cytotoxic concentrations of Eb and ZnCexFe2-XO4, oxidative stress and inflammatory milieu, autophagy, apoptosis, related signalling effectors, the distribution of cells through the cell-cycle phases, and the percentage of cells with apoptosis were evaluated in cancer cell lines. Additionally, the antimicrobial and antibiofilm potential have been investigated against different pathogenic microbes. The ZOI, and MIC results indicated that ZnCexFe2-XO4; X = 0.06 specimen reduced the activity of a wide range of bacteria and unicellular fungi at low concentration including P. aeruginosa (9.5 mm; 6.250 µg/mL), S. aureus (13.2 mm; 0.390 µg/mL), and Candida albicans (13.5 mm; 0.195 µg/mL). Reaction mechanism determination indicated that after ZnCexFe2-xO4; X = 0.06 treatment, morphological differences in S.aureus were apparent with complete lysis of bacterial cells, a concomitant decrease in the viable number, and the growth of biofilm was inhibited. The combination of Eb with ZFO or ZnCexFe2-XO4 with γ-radiation exposure showed marked anti-proliferative efficacy in both cell lines, through modulating the oxidant/antioxidant machinery imbalance, restoring the fine-tuning of redox status, and promoting an anti-inflammatory milieu to prevent cancer progression, which may be a valuable therapeutic approach to cancer therapy and as a promising antimicrobial agent to reduce the pathogenic potential of the invading microbes.

Coarse-grained molecular dynamics simulations of nanoplastics interacting with a hydrophobic environment in aqueous solution.

Nanoplastics (NPs) are emerging threats for marine and terrestrial ecosystems, but little is known about their fate in the environment at the molecular scale. In this work, coarse-grained molecular dynamics simulations were performed to investigate nature and strength of the interaction between NPs and hydrophobic environments. Specifically, NPs were simulated with different hydrophobic and hydrophilic polymers while carbon nanotubes (CNTs) were used to mimic surface and confinement effects of hydrophobic building blocks occurring in a soil environment. The hydrophobicity of CNTs was modified by introducing different hydrophobic and hydrophilic functional groups at their inner surfaces. The results show that hydrophobic polymers have a strong affinity to adsorb at the outer surface and to be captured inside the CNT. The accumulation within the CNT is even increased in presence of hydrophobic functional groups. This contribution is a first step towards a mechanistic understanding of a variety of processes connected to interaction of nanoscale material with environmental systems. Regarding the fate of NPs in soil, the results point to the critical role of the hydrophobicity of NPs and soil organic matter (SOM) as well as of the chemical nature of functionalized SOM cavities/voids in controlling the accumulation of NPs in soil. Moreover, the results can be related to water treatment technologies as it is shown that the hydrophobicity of CNTs and functionalization of their surfaces may play a crucial role in enhancing the adsorption capacity of CNTs with respect to organic compounds and thus their removal efficiency from wastewater.

Molecular level picture of the interplay between pH and phosphate binding at the goethite-water interface.

The soil pH plays a substantial role in controlling phosphorus (P) adsorption and mobilization. These processes are strongly affected by the phosphate interaction strength with P-fixing soil minerals such as goethite. The target of the current contribution is to draw a molecular level picture of the interplay between pH and phosphate binding at the goethite-water interface via a joint experimental-theoretical approach. Periodic density functional theory (DFT) calculations were carried out to provide a molecular level understanding of the pH dependence of P adsorption. To validate the modeling approach, adsorption experiments of phosphate at goethite were performed in the pH range of 4-12. There was agreement between experiments and simulations in the description of the adsorption behavior by two pH-dependent successive stages. The adsorption increases along the pH change from 4 to 8. A further increase of pH leads to a decrease of adsorption. By comparing with literature data it is concluded that the first stage will be observed only if there is no significant change of the surface charge at low pH. Moreover, the molecular modeling results point to the abundance of the monodentate (M) binding motif at both extremely low and high pH ranges. Otherwise, the bidentate (B) one is predominant along the intermediate pH range. These observations could resolve the existing debate about the assignment of phosphate-goethite binding motifs. Furthermore, the results point to a decrease of pH upon phosphate sorption due to an induced acidification of soil solution. The present joint experimental-theoretical approach provides a better understanding and description of the existing phosphate sorption experiments and highlights new findings at the atomistic/molecular scale.

Nanostructured Mg substituted Mn-Zn ferrites: A magnetic recyclable catalyst for outstanding photocatalytic and antimicrobial potentials.

With recently increasing the environmental problems and expected energy crisis, it is necessary to synthesis a low-cost, efficient, and UV-light responsive photocatalyst for contaminants' degradation. The nanostructured spinel ferrite Mn0.5Zn0.5-xMgxFe2O4 NPs (x = 0.0, 0.125, 0.25, 0.375 and 0.50) were synthesized via the sol-gel method. The crystallite size was lied in nano regime ranging from 21.8 to 36.5 nm. The surface chemical composition of the Mn0.5Zn0.5-xMgxFe2O4 NPs was investigated via XPS analysis. Mossbauer spectra showed that the peaks were shifted to higher values of the maximum magnetic field as the Mg content increased, indicating that the crystallinity is enhanced while the crystal size is decreased. Also, various parameters such as the photocatalyst dose, dyes concentration, pH, point of zero charge, and the metals leaching were studied. The point of zero charge (PZC) has found at pH = 2.38. The Mn0.5Zn0.125Mg0.375Fe2O4 NPs showed an excellent UV-assisted photocatalytic activity against Chloramine T (90 % removal efficiency) and Rhodamine B (95 % removal efficiency) after 80 min as compared to pure Mn0.5Zn0.5Fe2O4 ferrite NPs. Besides, it a recyclable catalyst at least four times with a negligible reduction of photocatalytic activity with slight elements leaching. Furthermore, the Mn0.5Zn0.25Mg0.25Fe2O4 NPs showed a high antimicrobial activity towards pathogenic bacteria and yeats.

SEM and molecular approaches to identify Calicophoron clavula in Saudi Arabia.

In the present study, Calicophoron clavula (Paramphistomidae), a parasite of rumina of sheep and cows, was collected from Taif region, KSA, to investigate its identity and the prevalence of infection in livestock. Specific identification was mainly achieved by ITS molecular technique and surface ultrastructure was studied by SEM. Adult C. clavula is described for the first time from Saudi Arabia. The infection rate is 1% in sheep and 10% in cows. Results indicated that this species isolate was genetically identical with other C. clavula isolates where matching reach 100%. The primary sequence of the rDNA ITS2+ region of the fluke produces amplicon of 647 bp. SEM results show that no observed papillae around its genital opening. Besides, it has very few scattered small papillae around its oral region with few randomly distributed acetabular papillae. These findings were compared with the same corresponding species in other previous works of literatures.

Ab Initio Molecular Dynamics Simulations of the Interaction between Organic Phosphates and Goethite.

Today's fertilizers rely heavily on mining phosphorus (P) rocks. These rocks are known to become exhausted in near future, and therefore effective P use is crucial to avoid food shortage. A substantial amount of P from fertilizers gets adsorbed onto soil minerals to become unavailable to plants. Understanding P interaction with these minerals would help efforts that improve P efficiency. To this end, we performed a molecular level analysis of the interaction of common organic P compounds (glycerolphosphate (GP) and inositol hexaphosphate (IHP)) with the abundant soil mineral (goethite) in presence of water. Molecular dynamics simulations are performed for goethite-IHP/GP-water complexes using the multiscale quantum mechanics/molecular mechanics method. Results show that GP forms monodentate (M) and bidentate mononuclear (B) motifs with B being more stable than M. IHP interacts through multiple phosphate groups with the 3M motif being most stable. The order of goethite-IHP/GP interaction energies is GP M < GP B < IHP M < IHP 3M. Water is important in these interactions as multiple proton transfers occur and hydrogen bonds are formed between goethite-IHP/GP complexes and water. We also present theoretically calculated infrared spectra which match reasonably well with frequencies reported in literature.

Clear Cell Sarcoma of the Foot in an 18-Year-Old Female.

We report a case of an 18-year-old female without a relevant medical history who presented with an 8-month history of a left foot mass. It started as a small nodule that progressively increased in size over time. The mass then became ulcerative with foul-smelling discharge. There was no palpable left inguinal or other lymph nodes upon physical examination. Histological examination of the biopsy confirmed a diagnosis of clear cell sarcoma. Clear cell sarcoma is a rare soft tissue neoplasm. However, early diagnosis is crucial to prevent metastasis and worsened prognosis. Clear cell sarcoma has an extremely poor prognosis once metastasis occurs, and to the best of our knowledge, only fewer than 100 cases have been reported in the literature.

Correlation between orthopaedic and radiographic examination findings and arthroscopic ligament fibre damage in dogs with cruciate ligament rupture.

OBJECTIVE: The objective is to study the correlations between physical examination and stifle radiography findings and severity of arthroscopic cranial cruciate ligament (CrCL) fibre damage in dogs with cruciate rupture (CR). DESIGN: Design Prospective clinical study. METHODS: Twenty-nine client-owned dogs with CR underwent physical examination, stifle radiography and arthroscopy, and the findings were recorded. Initial examination was repeated after sedation and after general anaesthesia. The Spearman rank correlations of examination variables with diagnostic imaging were examined. RESULTS: Overall, cranial tibial translation assessed by the tibial compression test in extension showed correlation with arthroscopic CrCL fibre damage (P < 0.05). Correlations between severity of cranial drawer laxity and arthroscopic CrCL fibre damage were not significant. Under general anaesthesia, stifle laxity tests were positively correlated with lameness severity grade (SR ≥ 0.41, P < 0.05). Meniscal damage was correlated with pain on the internal rotation of the tibia (SR = 0.42, P < 0.05) and severity of radiographic osteophytosis (SR = 0.53, P = 0.01). CONCLUSION: Detection and estimation of severity of cranial tibial translation enable the diagnosis of CR and also the inference of the severity of CrCL fibre rupture, particularly with the tibial compression test in extension. Severity of joint laxity is best assessed under general anaesthesia. Such knowledge should reduce the risk of misdiagnosis and may enhance early diagnosis and treatment of dogs with CR over time.

QM/MM simulations of organic phosphorus adsorption at the diaspore-water interface.

Phosphorus (P) immobilization and thus its availability for plants are mainly affected by the strong interaction of phosphates with soil components especially soil mineral surfaces. The related reactions have been studied extensively via sorption experiments especially by carrying out adsorption of ortho-phosphates onto Fe-oxide surfaces. But a molecular-level understanding of the P-binding mechanisms at the mineral-water interface is still lacking, especially for forest eco-systems. Therefore, the current contribution provides an investigation of the molecular binding mechanisms for two abundant phosphates in forest soils, inositol hexaphosphate (IHP) and glycerolphosphate (GP), at the diaspore mineral surface. Here a hybrid electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) based molecular dynamics simulation has been applied to explore the diaspore-IHP/GP-water interactions. The results provide evidence for the formation of different P-diaspore binding motifs involving monodentate (M) and bidentate (B) for GP and two (2M) as well as three (3M) monodentates for IHP. The interaction energy results indicated the abundance of the GP B motif compared to the M one. The IHP 3M motif has a higher total interaction energy compared to its 2M motif, but exhibits a lower interaction energy per bond. Compared to GP, IHP exhibited stronger interaction with the surface as well as with water. Water was found to play an important role in controlling these diaspore-IHP/GP-water interactions. The interfacial water molecules form moderately strong H-bonds (HBs) with GP and IHP as well as with the diaspore surface. For all the diaspore-IHP/GP-water complexes, the interaction of water with the diaspore exceeds that with the studied phosphates. Furthermore, some water molecules form covalent bonds with diaspore Al atoms while others dissociate at the surface to protons and hydroxyl groups leading to proton transfer processes. Finally, the current results confirm the previous experimental conclusions indicating the importance of the number of phosphate groups, HBs, and proton transfers in controlling the P-binding at soil mineral surfaces.

Influence of metal ions on glyphosate detection by FMOC-Cl.

Glyphosate (GLP, N-(phosphonomethyl)glycine) is the most important broadband herbicide in the world, but discussions are controversial regarding its environmental behaviour and distribution. Residue analyses in a variety of environmental samples are commonly conducted by HPLC-MS where GLP needs to be derivatised with 9-fluoromethoxycarnonyl chloride (FMOC-Cl). Since this derivatisation reaction was suspected to be inhibited by metal ions in the sample matrix, the present study provides a comprehensive experimental study of the effect of metal ions (Al3+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, Mg2+, Mn2+, Zn2+) on derivatisation and GLP recovery. Results show that some metals (Cd2+, Co2+, Cu2+, Mn2+ and Zn2+) decreased the GLP recovery down to 19 to 59%. Complementary, quantum chemical modelling of 1:1 GLP-metal complexes as well as their reactivity with respect to FMOC-Cl was performed. Here, a decrease in reactivity of FMOC-Cl towards GLP-metal complexes is observed; i.e. the reaction is non-spontaneous in contrast to the free GLP case. The present results are in accord with previous studies and provide an explanation that full GLP recovery in different matrices was never reached. Remedy strategies to compensate for the inhibition effect are explored such as pH adjustment to acidic or alkaline conditions or addition of ethylenediaminetetraacetic acid (EDTA). In general, our results question the use of internal isotopic labelled standards (ILS) since this presupposes the presence of the analyte and the ILS in the same (free) form.

Infrared spectroscopic characterization of phosphate binding at the goethite-water interface.

The interaction between phosphates and soil mineral surfaces, such as Fe- and Al-(oxyhydr)oxides, plays a crucial role in the immobilization of P and thus its availability for plants. The reactions of phosphates with Fe-hydroxides and especially goethite have been studied extensively. But a molecular-level picture of the phosphate binding mechanisms at the goethite-water interface is still lacking. Therefore, in the current contribution we have explored the molecular binding mechanisms for the adsorbed phosphate at the goethite-water interface by performing sorption kinetics experiments for orthophosphate and characterizing the adsorbed species by FT-IR spectroscopy. In parallel, periodic DFT calculations have been performed to explore the interaction mechanisms and to assign the IR spectra for monodentate (M) and bidentate (B) orthophosphate complexes at two different goethite surface planes (010 and 100) in the presence of water. In general, our interaction energy results give evidence that the mono-protonated B phosphate complex is favored to be formed at the goethite-water interface, although the M motif could exist as a minor fraction. Moreover, it was found that water plays an important role in controlling the phosphate adsorption process at the goethite surfaces. The interfacial water molecules form H-bonds (HBs) with the phosphate as well as with the goethite surface atoms. Furthermore, some water molecules form covalent bonds with goethite's Fe atoms while others dissociate at the surface to protons and hydroxyl groups. The present theoretical assignment of IR spectra introduces a benchmark for characterizing experimental IR data for the adsorbed KH2PO4 species at the goethite-water interface. In particular, the IR spectra of the mono-protonated (2O + 1Fe) B complex at the 010 goethite surface plane and the M complex at the 100 goethite surface plane were found to be consistent with the experimental data. In order to explore the role of different abundances of surface planes and binding motifs, IR spectra obtained from weighted averages have been analyzed. The results confirmed the conclusions drawn from interaction energy calculations.

Antibacterial, antibiofilm, and photocatalytic activities of metals-substituted spinel cobalt ferrite nanoparticles.

This study reports the photocatalytic degradation of Methylene Blue (MB) dye (a class of dyestuffs that are resistant to biodegradation) under the influence of UV-light irradiation. Antibacterial and antibiofilm activities of ferrite nanoparticles (FO NPs) were examined against some pathogenic bacteria isolated from the medical operating room surfaces. In the same context, metals-substituted spinel cobalt ferrite nanoparticles with nominal composition [MxCo1-xFe2O4 NPs; (M = Zn, Cu, Mn; x = 0.0, 0.25, 0.5 and 0.75)] were synthesized by citrate sol-gel method. Also, the structures of the synthesized FO NPs were characterized by X-ray diffraction, and Williamson-Hall (WH) method was used to determine the crystallite size. The estimated specific surface area is found in the range from 37.99 to 107.05 m2/g, between the synthesized ferrites, Zn0.5Co0.5Fe2O4 NPs have average pore radius 1.84 nm and the pore volume was 0.136 ml/g. SEM images revealed that, the synthesized FO NPs have an unique pores and uniformly distribution, while EDX spectra shows the elemental composition for the synthesized FO NPs. The elastic properties of FO NPs have been estimated using FTIR data, whereas (M - H) hysteresis loops revealed that, by replacing cobalt ions with Zn, Cu, and Mn ions the magnetic behaviour changed from ferromagnetic to paramagnetic. Results obtained from the photocatalysis indicated that Mn0.75Co0.25Fe2O4 NPs (30.0 mg) were a promising photocatalyst achieving 96.0% removal of MB after 100 min of UV-light exposure in the alkaline solution. Antibacterial results showed that the most effective combination was Zn0.75Co0.25Fe2O4 NPs (20.0 ppm) displaying activity against Staphylococcus aureus, Enterococcus columbae, and Aerococcus viridians by 15.0, 13.0, and 12.0 mm ZOI, respectively. Additionally, Zn0.75Co0.25Fe2O4 NPs were active as antibiofilm factors producing activity by 63.7, 57.9, and 45.5% towards S. aureus, A. viridians, and E. columbae, respectively. Accordingly, Zn0.75Co0.25Fe2O4 and Mn0.75Co0.25Fe2O4 NPs can be utilized in industrial, biological and medical applications.

Synthesis and characterization of metals-substituted cobalt ferrite [Mx Co(1-x) Fe2O4; (M = Zn, Cu and Mn; x = 0 and 0.5)] nanoparticles as antimicrobial agents and sensors for Anagrelide determination in biological samples.

Nanocrystalline spinel ferrite nanoparticles [MxCo(1-x)Fe2O4;(M = Zn,Cu,Mn;x = 0 and 0.5)] like: Cobalt ferrite (CFO), Zinc Cobalt ferrite (ZCFO), Copper Cobalt ferrite (CCFO), and Manganese Cobalt ferrite (MCFO) modified carbon paste electrodes (CPE) were synthesized via sol-gel technique utilizing citric acid and ethylene glycol as a polymerization agent. The synthesized ferrite NPs were used as bi-functional smart biosensor, not only used to determine the drug Anagrelide-HCl (ANDH) in urine and serum samples, but also possesses antimicrobial potential against some pathogenic microbes, founded in the biological samples. The synthesized ferrite NPs were confirmed by XRD, FTIR spectroscopy, SEM, EDX, and elemental mapping images. Antimicrobial activities of ferrite NPs against selected urinary tract infected microbes were investigated. From XRD data and FTIR spectroscopy it is found that the average crystallite size is lies in the range 12.86 to 33.92 ±â€¯1.5 nm, also the bond lengths RA and RB increase from 1.8986 to 1.9145 Šand from 2.0434 to 2.0606 Šrespectively and Debye temperature θD lies in the range of 681.52-708.87 K. Our study describes the improvement of a screen-printed sensor, modified with ferrite NPs materials for rapid, sensitive and cost-effective quantification of ANDH present in the real samples such as blood serum samples, urine and in the pharmaceutical formulations. The results obtained postulate a linear regression between the ANDH charge density of peak current and its concentration in the range from (0.64-8.18 µg/ml) with DL 0.31 µg/ml and QL 0.94 µg/ml. Antimicrobial results indicated that ZCFO NPs were a novel antibacterial agent against Klebsiella pneumoniae (28.0 mm ZOI), and multidrug-resistant bacteria Enterococcus faecalis (27.0 mm ZOI). Additionally, ZCFO NPs were active against Candida albicans (18.0 mm ZOI) seems to be a smart antifungal agent. Therefore, ZCFO NPs can be used as applicant resources for industrial, medical, and biological applications.