Investigation of phytochemicals isolated from selected Saudi medicinal plants as natural inhibitors of SARS CoV-2 main protease: In vitro, molecular docking and simulation analysis.

The escalation of many coronavirus variants accompanied by the lack of an effective cure has motivated the hunt for effective antiviral medicines. In this regard, 18 Saudi Arabian medicinal plants were evaluated for SARS CoV-2 main protease (Mpro) inhibition activity. Among them, Terminalia brownii and Acacia asak alcoholic extracts exhibited significant Mpro inhibition, with inhibition rates of 95.3 % and 95.2 %, respectively, at a concentration of 100 µg/mL. Bioassay-guided phytochemical study for the most active n-butanol fraction of T. brownii led to identification of eleven compounds, including two phenolic acids (1, and 2), seven hydrolysable tannins (3-10), and one flavonoid (11) as well as four flavonoids from A. asak (12-15). The structures of the isolated compounds were established using various spectroscopic techniques and comparison with known compounds. To investigate the chemical interactions between the identified compounds and the target Mpro protein, molecular docking was performed using AutoDock 4.2. The findings identified compounds 4, 5, 10, and 14 as the most potential inhibitors of Mpro with binding energies of -9.3, -8.5, -8.1, and -7.8 kcal mol-1, respectively. In order to assess the stability of the protein-ligand complexes, molecular dynamics simulations were conducted for a duration of 100 ns, and various parameters such as RMSD, RMSF, Rg, and SASA were evaluated. All selected compounds 4, 5, 10, and 14 showed considerable Mpro inhibiting activity in vitro, with compound 4 being the most powerful with an IC50 value of 1.2 µg/mL. MM-GBSA free energy calculations also revealed compound 4 as the most powerful Mpro inhibitor. None of the compounds (4, 5, 10, and 14) display any significant cytotoxic activity against A549 and HUVEC cell lines.

Sonographic reference values of nerve size in children: A systematic review and meta-analysis.

INTRODUCTION/AIMS: Nerve ultrasound is useful in the diagnosis and follow-up of peripheral nerve disorders in children. The aim of this study was to explore and analyze the current literature on nerve cross-sectional area (CSA) in healthy children, with the goal of presenting reference values and discussing their implications. METHODS: We performed a systematic review and meta-analysis of studies that reported ultrasound measurements of the upper or lower limb nerves in healthy children through a search of Web of Science, PubMed, Embase, and Scopus. RESULTS: Sixteen studies with measurements of 10 nerves covering a total of 5149 nerves measured in 823 healthy children (445 boys and 378 girls) were included. Mean nerve CSA increased with age in the median nerve at the middle and lower third of the upper arm, mid-forearm, and distal wrist crease, the ulnar nerve at the middle third of the upper arm and elbow, the radial nerve at the spiral groove, and the tibial nerve at the popliteal fossa. Growth charts for nerve CSA for different age groups were developed. DISCUSSION: This meta-analysis provides robust reference values for nerve CSA at different sites in children, and this can inform clinical practice and assist in identifying nerve enlargement. Moreover, it identifies the strength and quality of the current published data. We recommend future studies divide their samples into smaller age subgroups and standardize the anatomic site of measurement.

Improving the Durability of Chitosan Films through Incorporation of Magnesium, Tungsten, and Graphene Oxides for Biomedical Applications.

Bacterial infections that cause chronic wounds provide a challenge to healthcare worldwide because they frequently impede healing and cause a variety of problems. In this study, loaded with tungsten oxide (WO3 ), Magnesium oxide (MgO), and graphene oxide (GO) on chitosan (CS) membrane, an inexpensive polymer casting method was successfully prepared for wound healing applications. All fabricated composites were characterized by X-ray powder diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). A scanning electron microscope (SEM) was used to study the synthesized film samples' morphology as well as their microstructure. The formed WO3/MgO@CS shows a great enhancement in the UV/VIS analysis with a highly intense peak at 401 nm and a narrow band gap (3.69 eV) compared to pure CS. The enhanced electron-hole pair separation rate is responsible for the WO3/MgO/GO@CS scaffold's antibacterial activity. Additionally, human lung cells were used to determine the average cell viability of nanocomposite scaffolds and reached 121 % of WO3 /MgO/GO@CS nanocomposite, and the IC50 value was found to be 1654 µg/mL. The ability of the scaffold to inhibit the bacteria has been tested against both E. coli and S. aureus. The 4th sample showed an inhibition zone of 11.5±0.5 mm and 13.5±0.5 mm, respectively. These findings demonstrate the enormous potential for WO3 /MgO/GO@CS membrane as wound dressings in the clinical management of bacterially infected wounds.

The Association Between Shift Work and Migraine Attacks Among Healthcare Workers in the Kingdom of Saudi Arabia.

Introduction Migraine, a prevalent condition in Saudi Arabia, is linked to various risk factors, including night shifts. Existing literature, mainly outdated, suggests conflicting findings on the relationship between sleep, night shifts, and migraines. Our study aims to investigate the specific association between shift work and migraine attacks among healthcare workers in the Kingdom of Saudi Arabia (KSA), addressing a notable research gap. Methodology This is a cross-sectional study conducted in Saudi Arabia. Data were collected by using a non-probability convenience sampling technique. Data were collected through an online questionnaire and analyzed using SPSS version 26 (IBM Corp., Armonk, NY). Results Our study on 342 healthcare workers in the KSA revealed the majority of participants were females (70.5%, n = 241), aged between 25 and 29 years (38.9%, n = 133), with doctors being the predominant profession (51.5%, n = 176). Participants had an average of 5.9 years of healthcare experience. Work shifts included rotating (43.3%, n = 148), day (48%, n = 164), evening (3.8%, n = 13), and night shifts (5%, n = 17). Notably, 89.2% (n = 305) experienced headaches with varying characteristics and triggers. Management strategies included over-the-counter painkillers (56.1%, n = 192) and rest (50.5%, n = 173). Gender was significantly associated with migraines (p = 0.020), while night shift frequency and years in health care showed no significant associations. Higher weekly working hours relate significantly to migraines (p = 0.034). Conclusion Our study highlights a significant association between migraines and gender, with females being more prone. Night shift frequency and years in health care showed no significant associations, while higher weekly working hours were linked to migraines.

Corrosion mitigation characteristics of some novel organoselenium thiourea derivatives for acid pickling of C1018 steel via experimental and theoretical study.

Two organoselenium thiourea derivatives, 1-(4-(methylselanyl)phenyl)-3-phenylthiourea (DS036) and 1-(4-(benzylselanyl)phenyl)-3-phenylthiourea (DS038) were produced and categorized using FTIR and NMR (1H and 13C). The effectiveness of the above two compounds as C-steel corrosion inhibitors in molar HCl was evaluated using the potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS) techniques. PD findings indicate that DS036 and DS038 have mixed-type features. EIS results show that growing their dose not only changes the polarization resistance of C-steel from 18.53 to 363.64 and 463.15 Ω cm2 but also alters the double layer capacitance from 710.9 to 49.7 and 20.5 µF cm-2 in the occurrence of 1.0 mM of DS036 and DS038, respectively. At a 1.0 mM dose, the organoselenium thiourea derivatives displayed the highest inhibition efficiency of 96.65% and 98.54%. The inhibitory molecule adsorption proceeded along the Langmuir isotherm on the steel substrate. The adsorption-free energy of the adsorption process was also intended and indicated a combined chemical and physical adsorption on the C-steel interface. FE-SEM studies support the adsorption and protective abilities of the OSe-based molecule inhibitor systems. In Silico calculations (DFT and MC simulations) explored the attraction between the studied organoselenium thiourea derivatives and corrosive solution anions on a Fe (110) surface. The obtained results show that these compounds can make a suitable preventing surface and control the corrosion rate.

A Study of Misconceptions About Appendicitis Among the Resident Population of the Aseer Region.

BACKGROUND: Appendicitis is a common abdominal emergency requiring swift medical intervention. Misconceptions about this condition can lead to delayed diagnosis and potentially life-threatening complications. In the Aseer region of Saudi Arabia, where healthcare accessibility and awareness levels vary, addressing such misconceptions is of paramount importance. The aim of this study is to investigate and identify the prevalent misconceptions regarding appendicitis among the resident population of the Aseer region. Understanding the prevalent misconceptions and knowledge gaps is essential to develop targeted educational interventions and enhance public awareness. METHODS: This study utilized a cross-sectional study design to investigate misconceptions about appendicitis among residents in the Aseer region. Over a period of three months, 329 Aseer region resident population were interviewed. The symptoms, causes, diagnosis, treatment, and preventive measures of appendicitis were all covered in a questionnaire that was created to gather information on people's knowledge of appendicitis. Data were collected using an online questionnaire. Descriptive analysis was performed using frequencies and percentages, while inferential analysis employed appropriate statistical tests such as chi-square. RESULTS:  The study's 329 participants were made up of 56% men and 44% women. 40% of the sample size was between the ages of 18 and 30, 26% were between the ages of 31 and 40, 15% were between the ages of 41 and 50, and 10% were above 50 years, with those under the age of 18 years accounting for the smallest proportion (9%). The majority of the respondents (37%) were college graduates, 25% were college students, 23% were in high school and 15% were in middle school. Chi-square tests were conducted to examine the associations between background knowledge and pain area, as well as between background knowledge and source of information. For the association between background knowledge and pain area, the Chi-square test yielded a significant result (X² = 9.104, p = 0.028); the Chi-square test also revealed a significant result (X² = 8.078, p = 0.044) between background knowledge and the source of information about appendicitis. CONCLUSION: The analysis suggests a notable knowledge gap among the participants, with a significant portion displaying limited understanding or responding with "I don't know" when queried about appendicitis. It is important to note that this observation includes middle school students, who may be too young to be expected to possess knowledge about medical conditions. Additionally, there appears to be gender-related variation in opinions, misconceptions, and understanding regarding appendicitis.

Probiotics and Their Quality-Related Concerns: Highlights From the Saudi Arabian Market.

BACKGROUND: Probiotics are pharmaceutical products that contain living bacteria and are used to manage certain disorders, as well as to enhance general health. There are some reports criticizing the quality of these products, highlighting findings such as pathogen contamination and misleading labeling. Regulation and control of probiotics vary between international regulatory authorities, creating a gap between probiotic manufacturers and regulatory bodies. METHODS: In this article, the probiotics available in Saudi Arabia were analyzed in regard to their presented method of identification and labeling information. RESULTS: Only 1 of 22 products had confirmed the bacterial strain using a genotypic method; the rest presented various phenotypic methods. More than half of the reviewed products did not contain the strain designation on the outside labeling of the probiotic. CONCLUSION: The Saudi Food and Drug Authority should act by adopting a new guideline to control and regulate probiotics in Saudi Arabia, which could then be expanded to cover gulf countries (GCC).

Long-stay patients in pediatric intensive care units. Five-years, 2-points, cross-sectional study.

OBJECTIVES: To explore the changing patterns of long-stay patients (LSP) to improve the utilization of pediatric intensive care units (PICUs) resources. METHODS: This is a 2-points cross-sectional study (5 years apart; 2014-2019) conducted among PICUs and SCICUs in Riyadh, Saudi Arabia. Children who have stayed in PICU for more than 21 days were included. RESULTS: Out of the 11 units approached, 10 (90%) agreed to participate. The prevalence of LSP in all these hospitals decreased from 32% (48/150) in 2014 to 23.4% (35/149) in 2019. The length of stay ranged from 22 days to 13.5 years. The majority of LSP had a neuromuscular or cardiac disease and were admitted with respiratory compromise. Ventilator-associated pneumonia was the most prevalent complication (37.5%). The most commonly used resources were mechanical ventilation (93.8%), antibiotics (60.4%), and blood-products transfusions (35.4%). The most common reason for the extended stay was medical reasons (51.1%), followed by a lack of family resources (26.5%) or lack of referral to long-term care facilities (22.4%). CONCLUSION: A long-stay is associated with significant critical care bed occupancy, complications, and utilization of resources that could be otherwise utilized as surge capacity for critical care services. Decreasing occupancy in this multicenter study deserves further engagement of the healthcare leaders and families to maximize the utilization of resources.

Barriers to Health Care Services Among Palestinian Women Denied Family Unification in Israel.

Family unification received public and political attention following recent global immigration crises, though less within health research. In Israel, under the Family Reunification Order, about 20,000 Palestinian women from the Occupied Palestinian Territories are denied residency and the right to universal health care services (HSC) after marrying Palestinian citizens and moving to Israel. To better understand the relationship between lacking residency and barriers to accessing HCS, we conducted in-depth interviews with 21 Palestinian women (ages 22-59) denied family unification. Our findings revealed that in addition to hindering access to HCS, lacking residency intersects with other political, social, and economic determinants of these women's health and disrupts normal family life. Lacking residency intensifies poverty (via private health insurance and legal fees, permit extensions) and leads to family separations and risky crossings at military checkpoints into the West Bank for medical treatment. Restrictions on freedom of movement engender fear of deportation and precarity. Denial of residency also exacerbates gender inequality (increased dependence on husbands) and can endanger child custody when mothers' lack of residency passes to children, violating children's basic rights. Allowing family unification to Palestinian women would remove barriers to HCS access, allow normal family life, and permit social integration.

Variation in composite degree of conversion and microflexural strength for different curing lights and surface locations.

BACKGROUND: Lack of irradiance-beam profile uniformity across the emission area of light-curing units (LCUs) may result in suboptimal properties of composite restorations. The authors' objective for this study was to assess the variation in local cure of 1 composite at 3 different LCU emission area locations cured with 3 different LCUs by means of testing the degree of conversion (DC) and microflexural strength. METHODS: The authors fabricated dual-photoinitiator composite specimens (n = 5), which were cured using either a quartz-tungsten-halogen, a multiple-emission peak, or a single-emission peak light-emitting diode LCU. The specimen's top surfaces received irradiation from either the center, 1.5 millimeters straight to the left of the center, or 1.5 mm straight to the right of the center of the LCU emission area. The authors measured irradiance and DC on top and bottom specimen surfaces using a spectrometer and attenuated total reflection-Fourier transform infrared spectroscopy, respectively. The authors performed micro 3-point bend tests using a universal mechanical testing machine. They used multifactorial analysis of variance (α = 0.05). RESULTS: The irradiance ranged from 452 through 946 milliwatts per square centimeter, and DC ranged from 49.7% through 65.8% on top surfaces. Microflexural strength ranged from 313 through 458 megapascals. CONCLUSIONS: The authors did not find correlations among the LCU irradiance-beam profile of the 3 emission area locations and the investigated material properties, although they found variations in the measured properties. PRACTICAL IMPLICATIONS: The irradiance-beam profile from the different LCUs explored did not have a major influence on the DC and microflexural strength for the investigated composite.

Synthesis, biological and comparative DFT studies on Ni(II) complexes of NO and NOS donor ligands.

Three new NOS donor ligands have been prepared by addition ethanolic suspension of 2-hydrazino-2-oxo-N-phenyl-acetamide to phenyl isocyanate (H2PAPS), phenyl isothiocyanate (H2PAPT) and benzoyl isothiocyanate (H2PABT). The Ni(II) complexes prepared from the chloride salt and characterized by conventional techniques. The isolated complexes were assigned the formulaes, [Ni2(PAPS)(H2O)2](H2O)2, [Ni(H2PAPT)Cl2(H2O)](H2O)2 and [(Ni)2(HPABT)2Cl2(H2O)2], respectively. The IR spectra of complexes shows that H2PAPS behaves as a binegative pentadentate via both CO of hydrazide moiety in keto and enol form, enolized CO of cyanate moiety and the CN (azomethine) groups of enolization. H2PAPT behaves as neutral tridentate via both CO of hydrazide moiety and CN (azomethine) group due to SH formation and finally H2PABT behaves as mononegative tetradentate via CO and enolized CO of hydrazide moiety, CO of benzoyl moiety and C=S groups. The experimental IR spectra of ligands are compared with those obtained theoretically from DFT calculations. Also, the bond lengths, bond angles, HOMO (Highest Occupied Molecular Orbitals), LUMO (Lowest Unoccupied Molecular Orbital) and dipole moments have been calculated. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. The theoretical values of binding energies indicate the higher stability of complexes than of ligands. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. The antibacterial activities were also tested against B. Subtilis and E. coli bacteria. The free ligands showed a higher antibacterial effect than their Ni(II) complexes. The antitumor activities of the Ligands and their Ni(II) complexes have been evaluated against liver (HePG2) and breast (MCF-7) cancer cells. All ligands were found to display cytotoxicity that are better than that of Fluorouracil (5-FU), while Ni(II) complexes show low activity.

Synthesis, spectral characterization, computational calculations and biological activity of complexes designed from NNO donor Schiff-base ligand.

A new series of Co(II), Ni(II) and Cu(II) complexes of (Z)-2-oxo-2-(phenylamino)-N'-(1-(pyridin-2-yl)ethylidene)acetohydrazide (H2OPPAH) have been prepared and characterized by conventional techniques. The spectral data indicated that the ligand acts as neutral or mononegative NNO tridentate. On the basis of magnetic and electronic spectral data an octahedral geometry for Ni(II) and Cu(II) complexes and a tetrahedral geometry for Co(II) complex have been proposed. The molecular modeling using DFT method are drawn showing the bond length, bond angle, chemical reactivity, energy components (kcal/mol) and binding energy (kcal/mol) for all title compounds. The Kinetic parameters were determined for each thermal degradation stages of the ligand and its complexes using Coats-Redfern and Horowitz-Metzger methods. Also, the compounds were screened for antioxidant activity using ABTS free radical, anti-hemolytic, and in vitro cytotoxic assay. H2OPPAH showed the potent antioxidant activity followed by Co(II) and Cu(II) complexes. On the other hand Ni(II) complex exhibited weak antioxidant activity using ABTS free radical and Erlich and strong erythrocyte hemolysis activity.

Structural, spectral, thermal and biological studies on (Z)-N-benzoyl-N'-(2-oxo-2-(phenylamino)acetyl)carbamohydrazonothioic acid (H2PABT) and its Cd(II), Hg(II), Zn(II) and U(VI)O2²âº complexes.

A new metal complexes formed by the reaction of (Z)-N-benzoyl-N'-(2-oxo-2-(phenylamino)acetyl)carbamohydrazonothioic acid (H2PABT) and Cd(II), Hg(II), Zn(II) and U(VI)O2(2+) ions. The isolated complexes were prepared and characterized by conventional techniques. The IR data revealed that the ligand behaves as mononegative tridentate in Zn(II) and U(VI)O2(2+) complexes also, binegative tetradentate on Cd(II) and Hg(II) complexes. On the basis of magnetic and electronic spectral data an octahedral geometry for the U(VI)O2(2+) complex, a tetrahedral structure for the Cd(II), Zn(II) and Hg(II) complexes have been proposed. The IR spectrum of ligand which determined experimentally is compared with those obtained theoretically from DFT calculations. Also, the bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the ligand molecules. The calculated values of binding energies indicates the stability of complexes is higher that of ligand. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. Moreover, the ligand and its complexes were screened against Bacillus subtilis as Gram positive bacteria and Escherichia coli Gram negative bacteria using the inhibitory zone diameter. Also the antitumor activities of the ligand and its complexes have been evaluated against liver (HePG2) and breast (MCF-7) cancer cells. Out of all the synthesized compounds, [Hg2(PABT)Cl2(H2O)2] and [(UO2)(HPABT)(OAc)(H2O)] complexes showed high antibacterial activity with 55.5% while H2PABT showed the best cytotoxic effect on liver and breast cancer cells with IC50 2.10 and 5.91 of cytotoxicity respectively.

Topography of orientation centre connections in the primary visual cortex of the cat.

The functional topography of lateral connections to orientation-centre zones was studied by optical imaging of intrinsic signals in combination with tracer injections (fluorescent beads and biocytin) and electrophysiological recordings. Three-dimensional reconstruction of anterogradely labelled axon terminals and retrogradely labelled somata revealed a uniform distribution across all orientations in a non-patchy manner. The overall lateral extent of the labelling was 3-4 mm in layer 3, that is about half of the extent observed for orientation domain connections in the same layer. These bulk injection data are in contrast with the reportedly sharp orientation tuning of neurons of centre zones and suggest that orientation specificity here does not require highly specific connections. Nonetheless, another plausible scenario is that orientation centre connections are orientation specific but their specificity present at the single cell level cannot be revealed by bulk labelling due to their large spatial overlap.

Computational studies of the first order kinetic reactions for mononuclear copper(II) complexes having a hard-soft NS donor ligand.

The chelation behaviour of 4-((E)-2-(1-(thiophen-2-yl)ethylidene)hydrazinyl)-1-(4-methoxyphenyl)-1H-pyrrole-3-carbonitrile (HL) towards Cu(II) ions has been investigated. These Cu(II) complexes are characterized by elemental analyses, molar-solid conductance, ESR, FTIR and electronic spectral studies. Also, the kinetic and thermodynamic parameters (Ea, A, ΔH, ΔS, ΔG) for all thermal decomposition steps have been evaluated using Coats-Redfern and Horowitz-Metzger methods. Furthermore, antimicrobial activity of the ligand and its complexes were studied against Gram-negative bacteria: Escherichia coli, Gram-positive Bacillus cereus, Bacillus subtilis and pathogenic fungi Pseudomonas aeruginosa by using minimum inhibitory concentrations (MICs) method.

Synthesis, spectral characterization and biological evaluation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with thiosemicarbazone ending by pyrazole and pyridyl rings.

Here we present the synthesis of the new Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with chelating ligand (Z)-(2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene) hydrazinyl)(pyridin-2-ylamino)methanethiol. All the complexes were characterized by elemental analysis, IR, (1)H NMR, UV-vis, magnetic susceptibility measurements and EPR spectral studies. IR spectra of complexes showed that the ligand behaves as NN neutral bidentate, NSN mononegative tridentate and NSNN mononegative tetradentate. The electronic spectra and the magnetic measurements suggested the octahedral geometry for all complexes as well as the EPR confirmed the tetragonal distorted octahedral for Cu(II) complex. Cd(II) complex showed the highest inhibitory antioxidant activity either using ABTS method. The SOD-like activity exhibited those Cd(II) and Zn(II) complexes have strong antioxidative properties. We tested the synthesized compounds for antitumor activity and showed that the ability to kill liver (HePG2) and breast (MCF-7) cancer cells definitely.

Structural, spectral, thermal and biological studies on (E)-2-(1-(4-hydroxyphenyl)ethylidene)-N-(pyridin-2-yl)hydrazinecarbothioamide and its metal complexes.

Schiff base complexes of Mn(II), Co(II), Ni(II), Cu(II), Cd(II), Hg(II) and U(VI)O2 with (E)-2-(1-(4-hydroxyphenyl)ethylidene)-N-(pyridin-2-yl)hydrazinecarbothioamide (H2PHAT) were synthesized and characterized by different physicochemical methods, elemental analysis, (UV-vis, IR and (1)H NMR spectra) and thermal analysis (TG and DTG) techniques. Spectral data showed that H2PHAT behaves as a NS bidentate ligand through both thione sulphur or thiol sulphur and the nitrogen of the pyridine ring or azomethine nitrogen, NSN tridentate ligand through both thione sulphur or thiol sulphur, the nitrogen of the pyridine ring and azomethine nitrogen. ESR spectrum data for Cu(II) solid complex confirms the square planar state is the most fitted one for the coordinated structure. The kinetic parameters were determined for each thermal degradation stage of the complexes using Coats-Redfern and Horowitz-Metzger methods. From modeling studies, the bond length, bond angle, HOMO, LUMO and dipole moment had been calculated to confirm the geometry of the ligand and their investigated complexes. The biological activity was tested against DNA showing that Cd(II), U(VI)O2, Ni(II) and Mn(II) complexes had powerful and complete degradation effect. Also, the ligand and its complexes were screened against Bacillus thuringiensis as Gram-positive bacteria and Pseudomonas aeuroginosa as Gram-negative bacteria using the inhibitory zone diameter.

Co(II), Cd(II), Hg(II) and U(VI)O2 complexes of o-hydroxyacetophenone[N-(3-hydroxy-2-naphthoyl)] hydrazone: physicochemical study, thermal studies and antimicrobial activity.

The o-Hydroxy acetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H(2)o-HAHNH) has been prepared and its structure is confirmed by elemental analysis, IR, (1)H NMR and (13)C NMR spectroscopy. It has been used to produce diverse complexes with Co(II), Cd(II), Hg(II) and U(VI)O(2) ions. The isolated complexes have been investigated by elemental analysis, magnetic measurements, molar conductivity, thermal (TG, DTG) and spectral ((1)H NMR, (13)C NMR, IR, UV-visible, MS) studies. Infrared spectra suggested H(2)o-HAHNH acts as a bidentate and/or tridentate ligand. The electronic spectrum of [Co(Ho-HAHNH)(2)] complex as well as its magnetic moments suggesting octahedral geometry around Co(II) center. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. Moreover, the kinetic and thermodynamic parameters (Ea, A, ΔH, ΔS and ΔG) for the different decomposition steps of the [Co(Ho-HAHNH)(2)] and [Cd(Ho-HAHNH)(2)] complexes were calculated using the Coats-Redfern and Horowitz-Metzger methods. Moreover, the antibacterial and antifungal activities of the isolated compounds were studied using a wide spectrum of bacterial and fungal strains.

First row transition metal complexes of (E)-2-(2-(2-hydroxybenzylidene) hydrazinyl)-2-oxo-N-phenylacetamide complexes.

Manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and chromium(III) complexes of (E)-2-(2-(2-hydroxybenzylidene)hydrazinyl)-2-oxo-N-phenylacetamide were synthesized and characterized by elemental and thermal (TG and DTA) analyses, IR, UV-vis and (1)H NMR spectra as well as magnetic moment. Mononuclear complexes are obtained with 1:1 molar ratio except [Mn(HOS)(2)(H(2)O)(2)] and [Co(OS)(2)](H(2)O)(2) complexes which are obtained with 1:2 molar ratios. The IR spectra of ligand and metal complexes reveal various modes of chelation. The ligand behaves as a monobasic bidentate one and coordination occurs via the enolic oxygen atom and azomethine nitrogen atom. The ligand behaves also as a monobasic tridentate one and coordination occurs through the carbonyl oxygen atom, azomethine nitrogen atom and the hydroxyl oxygen. Moreover, the ligand behaves as a dibasic tridentate and coordination occurs via the enolic oxygen, azomethine nitrogen and the hydroxyl oxygen atoms. The electronic spectra and magnetic moment measurements reveal that all complexes possess octahedral geometry except the copper complexes possesses a square planar geometry. From the modeling studies, the bond length, bond angle, HOMO, LUMO and dipole moment had been calculated to confirm the geometry of the ligands and their investigated complexes. The thermal studies showed the type of water molecules involved in metal complexes as well as the thermal decomposition of some metal complexes. The protonation constant of the ligand and the stability constant of metal complexes were determined pH-metrically in 50% (v/v) dioxane-water mixture at 298 K and found to be consistent with Irving-Williams order. Moreover, the minimal inhibitory concentration (MIC) of these compounds against Staphylococcus aureus, Escherechia coli and Candida albicans were determined.

Generation of magnetic field by combined action of turbulence and shear.

The feasibility of a mean-field dynamo in nonhelical turbulence with a superimposed linear shear is studied numerically in elongated shearing boxes. Exponential growth of the magnetic field at scales much larger than the outer scale of the turbulence is found. The characteristic scale of the field is lB proportional S(-1/2) and the growth rate is gamma proportional S, where S is the shearing rate. This newly discovered shear dynamo effect potentially represents a very generic mechanism for generating large-scale magnetic fields in a broad class of astrophysical systems with spatially coherent mean flows.