Structural insight into the cooperativity of spin crossover compounds.

Spin-crossover (SCO) compounds are promising materials for a wide variety of industrial applications. However, the fundamental understanding of their nature of transition and its effect on the physical properties are still being fervently explored; the microscopic knowledge of their transition is essential for tailoring their properties. Here an attempt is made to correlate the changes in macroscopic physical properties with microscopic structural changes in the orthorhombic and monoclinic polymorphs of the SCO compound Fe(PM-Bia)2(NCS)2 (PM = N-2'-pyridylmethylene and Bia = 4-aminobiphenyl) by employing single-crystal X-ray diffraction, magnetization and DSC measurements. The dependence of macroscopic properties on cooperativity, highlighting the role of hydrogen bonding, π-π and van der Waals interactions is discussed. Values of entropy, enthalpy and cooperativity are calculated numerically based on the Slichter-Drickamer model. The particle size dependence of the magnetic properties is probed along with the thermal exchange and the kinetic behavior of the two polymorphs based on the dependence of magnetization on temperature scan rate and a theoretical model is proposed for the calculation of the non-equilibrium spin-phase fraction. Also a scan-rate-dependent two-step behavior observed for the orthorhombic polymorph, which is absent for the monoclinic polymorph, is reported. Moreover, it is found that the radiation dose from synchrotron radiation affects the spin-crossover process and shifts the transition region to lower temperatures, implying that the spin crossover can be tuned with radiation damage.

Does Red Cell Distribution Width Predict Hip Fracture Mortality Among the Arab Population? A Single-Center Retrospective Cohort Study.

BACKGROUND: Hip fractures impose significant morbidity and mortality. Red cell distribution width (RDW) appears to be an emerging tool in predicting mortality following hip fractures. Several factors can influence the RDW value including genetic factors and ethnicity. The purpose of the study was to assess the relation between RDW level at admission and hip fracture mortality within 6 months among Arab/Middle East populations. METHODS: We conducted a single-center retrospective cohort study including 549 patients (274 female and 275 male) diagnosed with a hip fracture undergoing surgery from February 2016 to December 2019. All included patients shared the same country of origin which is Arab Middle East country. Statistical analysis, including binary regression, was performed to assess the relationship between RDW and mortality within 6 months of admission. Other predictors of mortality following hip fracture surgery were also assessed. RESULTS: The mean age was 76.42 (±9.19) years. Seventy (12.8%) of participants died within 6 months. No statistically significant association (P=0.053) between RDW level at admission and mortality within 6 months of surgery was found. Binary regression demonstrated that the only independent predictors of mortality were age (P= 0.003, odds ratio 1.048 with 95% CI 1.016 to 1.080) and male gender (P= 0.021, odds ratio 1.872 with 95% CI 1.100 to 3.185). CONCLUSION: Although the previous studies reported that RDW is one of the predictors of mortality in hip fracture patients, our study found no relation in the Arab population. This finding may confirm the influence of genetic factors and ethnicity on RDW value. We recommend further large-scale multicenter studies to solidly establish the relationship between RDW and hip fracture mortality among the Arab/Middle East population.

Oral health status of children with autistic disorder in Chennai.

AIM: To assess the oral health status of autistic children in Chennai. DESIGN AND METHODS: Oral health status was assessed for 483 children with autism, solicited from special education schools, autistic child centres and therapy centres. Conditions assessed were plaque accumulation, gingival health, dental caries, malocclusion, developmental anomalies, oral injuries and restorations. STATISTICS: Chi-square and Fisher's exact tests of significance were used to compare groups. Proportions test was used to compare the significance of the parameters between boys and girls. RESULTS: Autistic children with primary dentition showed significantly higher incidence of dental caries (24%), when compared to other oral conditions. Children with mixed dentition had more gingivitis (50%) and children with permanent dentition had more gingivitis (48.96%) and malocclusion (71.15%). All the oral conditions were seen more in boys than girls. CONCLUSION: Autistic children have significantly poor oral hygiene and higher incidence of malocclusion and dental caries when compared to other oral conditions.