Elucidating Structure-Property Correlation in Perovskitoid and Antiperovskite Piperidinium Manganese Chloride.

In the world of semiconductors, organic-inorganic hybrid (OIH) halide perovskite is a new paradigm. Recently, a zealous effort has been made to design new lead-free perovskite-like OIH halides, such as perovskitoids and antiperovskites, for optoelectronic applications. In this context, we have synthesized a perovskitoid compound (Piperidinium)MnCl3 (compound 1) crystallizing in an orthorhombic structure with infinite one-dimensional (1D) chains of MnCl6 octahedra. Interestingly, this compound shows switchable dielectric property governed by an order-disorder structural transition. By controlling the stoichiometry of piperidine, we have synthesized an antiperovskite (Piperidinium)3Cl[MnCl4] (compound 2), the inverse analogue of a perovskite, consisting of zero-dimensional (0D) MnCl4 tetrahedra. This type of organic-inorganic hybrid antiperovskite halide is unique and scarce. Such a dissimilarity in lattice dimensionality and Mn2+ ion coordination ensues fascinating photophysical and magnetic properties. Compound 1 exhibits red emission with a photoluminescence quantum yield (PLQY) of ∼28%. On the other hand, the 0D antiperovskite compound 2 displays green emission with a higher PLQY of 54.5%, thanks to the confinement effect. In addition, the dimensionality of the compounds plays a vital role in the exchange interaction. As a result, compound 1 shows an antiferromagnetic ground state, whereas compound 2 is paramagnetic down to 1.8 K. This emerging structure-property relationship in OIH manganese halides will set the platform for designing new perovskites and antiperovskites.

Zero-Dimensional (Piperidinium)2MnBr4: Ring Puckering-Induced Isostructural Transition and Strong Electron-Phonon Coupling-Mediated Self-Trapped Exciton Emission.

We report on the synthesis, structure, and photophysical properties of a lead-free organic-inorganic hybrid halide, (Piperidinium)2MnBr4 (PipMBr). It crystallizes in a monoclinic P21/n structure, with isolated MnBr4 tetrahedra representing a zero-dimensional compound. It undergoes a reversible isostructural transition at 422/417 K in the heating/cooling cycle owing to the hydrogen-bonding rearrangement mediated by ring puckering of piperidinium cations. This compound exhibits green emission with a photoluminescence quantum yield of 51%. Interestingly, strong electron-longitudinal optical phonon coupling with γLO of 237 meV is evidenced from the broadening of the temperature-dependent emission linewidth and the Raman spectrum. Such strong electron-phonon coupling and a relatively low Debye temperature (137 K) suggest the self-trapped exciton emission in this compound.

Electron-Phonon Coupling Mediated Self-Trapped-Exciton Emission and Internal Quantum Confinement in Highly Luminescent Zero-Dimensional (Guanidinium)6Mn3X12 (X = Cl and Br).

We report a large Stokes shift and broad emission band in a Mn-based organic-inorganic hybrid halide, (Guanidinium)6Mn3Br12 [GuMBr], consisting of trimeric units of distorted MnBr6 octahedra representing a zero-dimensional compound with a liquid like crystalline lattice. Analysis of the photoluminescence (PL) line width and Raman spectra reveals the effects of electron-phonon coupling, suggestive of the formation of Frenkel-like bound excitons. These bound excitons, regarded as the self-trapped excitons (STEs), account for the large Stokes shift and broad emission band. The excited-state dynamics was studied using femtosecond transient absorption spectroscopy, which confirms the STE emission. Further, this compound is highly emissive with a PL quantum yield of ∼50%. With chloride ion incorporation, we observe enhancement of the emissive properties and attribute it to the effects of intrinsic quantum confinement. Localized electronic states in flat bands lining the gap and their strong coupling with phonons are confirmed with first-principles calculations.

Prevalence, severity, and risk factors for acute exacerbations of nasal and sinus symptoms by chronic rhinosinusitis status.

BACKGROUND: Nasal and sinus symptoms (NSS) are common to many health conditions, including chronic rhinosinusitis (CRS). Few studies have investigated the occurrence and severity of, and risk factors for, acute exacerbations of NSS (AENSS) by CRS status (current, past, or never met European Position Paper on Rhinosinusitis [EPOS] criteria for CRS). METHODS: Four seasonal questionnaires were mailed to a stratified random sample of Geisinger primary care patients. Logistic regression was used to identify individual characteristics associated with AENSS occurrence and severity by CRS status (current long-term, current recent, past, never) using EPOS subjective symptoms-only (EPOSS ) CRS criteria. We operationalized 3 AENSS definitions based on prescribed antibiotics or oral corticosteroids, symptoms, and symptoms with purulence. RESULTS: Baseline and at least 1 follow-up questionnaires were available from 4736 subjects. Self-reported NSS severity with exacerbation was worst in the current long-term CRS group. AENSS was common in all subgroups examined and generally more common among those with current EPOSS CRS. Seasonal prevalence of AENSS differed by AENSS definition and CRS status. Associations of risk factors with AENSS differed by definition, but CRS status, body mass index, asthma, hay fever, sinus surgery history, and winter season consistently predicted AENSS. CONCLUSIONS: In this first longitudinal, population-based study of 3 AENSS definitions, NSS and AENSS were both common, sometimes severe, and differed by EPOSS CRS status. Contrasting associations of risk factors for AENSS by the different definitions suggest a need for a standardized approach to definition of AENSS.

Longitudinal evaluation of clustering of chronic sinonasal and related symptoms using exploratory factor analysis.

BACKGROUND: Sinonasal symptoms are common and can have several underlying causes. When symptoms occur in specified patterns lasting 3 months or more they meet criteria for chronic rhinosinusitis (CRS). Approaches to CRS symptom measurement do not specify how to measure symptoms and treat specified sinonasal symptoms as generally interchangeable, suggesting that such symptoms should cluster on 1 or 2 latent factors. METHODS: We used questionnaire responses to 37 questions on the presence, severity, bother, and frequency of cardinal sinonasal and related symptoms lasting 3 months, from 3535 subjects at 3 time points over 16 months. We completed 5 exploratory factor analyses (EFA) to identify symptom clustering, 1 for each time point and 2 for the differences between adjacent questionnaires. The baseline EFA was used to provide factor scores that were described longitudinally and examined by CRS status. RESULTS: Five EFAs identified the same 5 factors (blockage and discharge, pain and pressure, asthma and cold/flu symptoms, smell loss, and ear and eye [mainly allergy] symptoms), with clustering determined by symptom frequency, severity, and degree of bother. Responses to individual questions showed changes over time but when combined into factor scores showed less longitudinal change. All symptom factor scores were progressively higher from never to past to current CRS status. CONCLUSIONS: Although the current approaches to symptom characterization in CRS imply a single underlying latent construct, our results suggest that there are at least 3 latent constructs relevant to CRS. Further studies are needed to evaluate whether these clusters have identifiable underlying pathobiologies.

Synthesis, Structure, and Physical Properties of the Polar Magnet DyCrWO6.

It has recently been reported that the ordered aeschynite-type polar ( Pna21) magnets RFeWO6 (R = Eu, Tb, Dy, Y) exhibit type II multiferroic properties below TN ∼ 15-18 K. Herein, we report a comprehensive investigation of the isostructural oxide DyCrWO6 and compare the results with those of DyFeWO6. The cation-ordered oxide DyCrWO6 crystallizes in the same polar orthorhombic structure and undergoes antiferromagnetic ordering at TN = 25 K. Contrary to DyFeWO6, only a very weak dielectric anomaly and magnetodielectric effects are observed at the Néel temperature and, more importantly, there is no induced polarization at TN. Furthermore, analysis of the low-temperature neutron diffraction data reveals a collinear arrangement of Cr spins but a noncollinear Dy-spin configuration due to single-ion anisotropy. We suggest that the collinear arrangement of Cr spins may be responsible for the absence of electric polarization in DyCrWO6. A temperature-induced magnetization reversal and magnetocaloric effects are observed at low temperatures.

Nasal and sinus symptoms and chronic rhinosinusitis in a population-based sample.

BACKGROUND: The objective of this study was to describe the first US-based study to use the European Position Paper on Rhinosinusitis (EPOS) criteria to study the prevalence of chronic rhinosinusitis (CRS) in a general-population sample. METHODS: A CRS symptom questionnaire was mailed to 23 700 primary care patients from Geisinger Clinic, a health system serving 45 counties in Pennsylvania. CRS cases were categorized into four unique subgroups based on EPOS symptoms: obstruction and discharge with no smell loss or pain/pressure; smell loss without pain/pressure; facial pain and/or pressure without smell loss; and both smell loss and pain/pressure. All cases were required to have nasal obstruction or discharge. Logistic regression was used to evaluate potential factors associated with CRS subgroups. RESULTS: We found that 11.9% of patients met criteria for CRS. Prevalence peaked at 15.9% between ages 50 and 59 years and then dropped to 6.8% after age 69. The odds of CRS was higher among patients who were white, younger, smokers, had a history of Medical Assistance, and had other diseases. When CRS subgroups were modeled separately, these associations were no longer significant for some CRS subgroups. Comorbid diseases were most strongly associated with CRS cases who reported smell loss and facial pain and/or pressure and had the weakest associations with CRS cases who did not report these symptoms. CONCLUSIONS: CRS is a highly prevalent and heterogeneous condition. Differences in risk factors and health outcomes across symptom subgroups may be indicative of differences in etiology that have implications for disease management.

Quantification of phenolics in Syzygium cumini seed and their modulatory role on tertiary butyl-hydrogen peroxide-induced oxidative stress in H9c2 cell lines and key enzymes in cardioprotection.

The study quantified the major phenolics in different fractions of Syzygium cumini seeds and evaluated their cardioprotective efficacy. Gallic acid, ellagic acid, cinnamic acid, quercetin, syringic acid and ferulic acid were the major polyphenols present in different fractions of Syzygium cumini seeds. The cardioprotective effect of Syzygium cumini seed fractions in modulating angiotensin converting enzyme (ACE), HMG-CoA reductase, LDL oxidation and tertiary butyl hydrogen peroxide (TBHP) induced oxidative stress in H9c2 cardiac cell lines were investigated. Syzygium cumini effectively attenuated the cellular oxidative stress in H9c2 cardiomyoblasts. These fractions possessed inhibitory potential against ACE, HMG-CoA reductase and LDL oxidation. Molecular docking studies of the predominant polyphenols with ACE and HMG-CoA proteins revealed the binding interactions of these compounds, thus confirming their modulation of activity. The present study demonstrated the cardioprotective efficacy of Syzygium cumini seed fractions which can be attributed to the presence of phenolic acids and flavonoids.

Five-year risk of incident disease following a diagnosis of chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) has a broad range of comorbidities. Due to a lack of longitudinal studies, it is not known whether these comorbidities cause CRS, are promoted by CRS, or share a systemic disease process with CRS. OBJECTIVE: The objective of this study was to determine the risk of incident disease within 5 years after a new diagnosis of CRS with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP). METHODS: We conducted a case-control study nested within the longitudinal cohort of primary care patients in the Geisinger Clinic using electronic health record data. We evaluated incident disease over 5 years in newly diagnosed CRSwNP and CRSsNP cases compared to controls using multivariable Cox regression models. RESULTS: CRSsNP (n = 3612) cases were at greater risk (HR, 95% confidence interval) than controls for incidence of: upper airway diseases, including adenotonsillitis (3.29, 2.41-4.50); lower aerodigestive tract diseases, including asthma (2.69, 2.14-3.38); epithelial conditions, including atopic dermatitis (2.75, 1.23-6.16); and hypertension (1.38, 1.19-1.61). CRSwNP (n = 241) cases were at greater risk for obesity than controls (1.74, 1.08-2.80), but CRSwNP was not associated with other diseases. CONCLUSION: The risk of other diseases associated with CRS adds to the burden of an already highly burdensome condition, and suggests either that CRS promotes onset of other diseases or is an indicator of systemic disease processes. Different patterns of association with diseases by CRS phenotype may be due to CRSwNP sample size limitations or reflect a different pattern of disease onset by phenotype. These findings have implications for screening guidelines and care of CRS patients.

Effect on oxidative stress, glucose uptake level and lipid droplet content by Apigenin 7, 4'-dimethyl ether isolated from Piper longum L.

Piper longum L. (Family: Piperaceae), is a widely used herb in several Ayurvedic formulations prescribed for various diseases. Potential of the plant material as an antidiabetic and cardio protective agent has not been evaluated so far. In the study, we designed experiments to evaluate antioxidant, glucose uptake potential and lipid content regulating potential of extracts and compound from P. longum fruits. Solvent extracts from Piper longum fruits using hexane, ethyl acetate, methanol, 70 % methanol-water were taken and apigenin 7, 4'-dimethyl ether (ADE) was isolated from ethyl acetate extract. Antioxidant activity, glucose uptake potential and adipocyte differentiation assay was performed with extract and pure compound. Antioxidant activity in terms of TRP (196.03 µg/mg GAE), DPPH assay (IC50-173.09 µg/mL), hydroxyl radical scavenging assay (IC50-20.42 µg/mL), inhibiting LDL oxidation (IC50-51.99 µg/mL) and to enhance SOD activity (25.3 %) was higher in ethyl acetate extract (EAP). Phenolic and flavonoid content was measured and showed a positive correlation with antioxidant activity. Presence of apigenin 7, 4'-dimethyl ether (ADE) and piperine (Pip) in EAP was determined by HPTLC analysis and was isolated. ADE inhibited α-glucosidase and α-amylase enzymes and enhanced 2-NBDG uptake in L6 cells. Hypolipidemic effect of ADE on mouse pre-adipocyte (3T3L1) cell lines also showed a dose dependent reduction on lipid droplet content and effective concentration range was determined as 1-2.5 µg/mL. The results suggested that Piper longum fruits can provide a natural source of antioxidants with antidiabetic and anti obesity potential.

Influence of natural and synthetic antioxidants on the degradation of Soybean oil at frying temperature.

The effect of several natural and synthetic antioxidants to retard the formation of polar compounds and thermo-oxidation at prolonged frying temperatures was studied. Antioxidants, including butyl hydroxyl toluene (BHT), ter-butyl hydroxyquinone (TBHQ), α- and γ-tocopherols, tocopherol mixture (α, ß, γ and δ), sesamol, ß-sitosterol, ß-sitostanol, γ-oryzanol, curcumin, rosemary extract and sucrose acetate isobutyrate (SAIB) were tested in refined soybean oil without added any additives recovered from refinery. Rosemary extract and SAIB were showed a considerable effect on both polar compound formation and secondary oxidation. These compounds increased the oxidative stability of oil for more than 30 % compared to conventional synthetic antioxidants. Oils treated with SAIB showed higher color retention after 6 h heating compared to the oils added with BHT, TBHQ and tocopherols. Curcumin, sesamol and γ-oryzanol showed higher antioxidant potential compared to other antioxidants. Preliminary results obtained from this study have clearly demonstrated that SAIB and rosemary extracts are more commercially viable antioxidants to increase the stability of frying oils.

Enhanced thermal oxidation stability of reduced graphene oxide by nitrogen doping.

Nitrogen-doped reduced graphene oxide (N-doped RGO) samples with a high level of doping, up to 13 wt. %, have been prepared by annealing graphene oxide under a flow of pure ammonia. The presence of nitrogen within the structure of RGO induces a remarkable increase in the thermal stability against oxidation by air. The thermal stability is closely related with the temperature of synthesis and the nitrogen content. The combustion reaction of nitrogen in different coordination environments (pyridinic, pyrrolic, and graphitic) is analyzed against a graphene fragment (undoped) from a thermodynamic point of view. In agreement with the experimental observations, the combustion of undoped graphene turns out to be more spontaneous than when nitrogen atoms are present.

The absence of ferroelectric polarization in layered and rock-salt ordered NaLnMnWO6 (Ln = La, Nd, Tb) perovskites.

The ordered perovskites, NaLnMnWO6 (Ln = La, Nd, Tb), are reported to exhibit simultaneous ordering of A-site cations (Na and Ln) in layered arrangement and B-site cations (Mn and W) in rock salt structure. They have been shown to crystallize in a monoclinic structure with the polar space group P21. Based on density functional calculations and group theoretical analysis, it has recently been proposed that NaLaMnWO6 should be ferroelectric with a relatively large polarization (16 µC cm(-2)). Contrary to this prediction, our electrical measurements such as conventional P-E loop, Positive-Up and Negative-Down (PUND), piezoelectric response and Second Harmonic Generation (SHG) reveal the absence of ferroelectric polarization in NaLnMnWO6 (Ln = La, Nd, Tb). A dielectric anomaly is observed just below room temperature (∼270 K) for all the three compounds, which is related to the change in conductivity as revealed by temperature dependent ac and dc resistivity. A pyrocurrent peak is also observed at the same temperature. However, its origin cannot be attributed to a ferroelectric transition.

Negative magnetization and magnetic ordering of rare earth and transition metal sublattices in NdFe0.5Cr0.5O3.

We investigate the effect of alloying at the 3dtransition metal site of a rare-earth-transition metal oxide, by considering NdFe0.5Cr0.5O3mixed perovskite with two equal and random distribution of 3d ions, Cr and Fe, interacting with an early 4f rare earth ion, Nd. Employing temperature- and field- dependent magnetization measurements, temperature-dependent x-ray diffraction, neutron powder diffraction, and Raman spectroscopy, we characterize its structural and magnetic properties. Our study reveals bipolar magnetic switching (arising from negative magnetization) and magnetocaloric effect which underline the potential of the studied mixed perovskite in device application. The neutron diffraction study shows the absence of spin reorientation transition over the entire temperature range of 1.5-320 K, although both parent compounds exhibit spin orientation transition. We discuss the microscopic origin of this curious behavior. The neutron diffraction results also reveal the ordering of Nd spins at an unusually high temperature of about 40 K, which is corroborated by Raman measurements.

Synthesis, characterization, photocatalysis, and varied properties of TiO2 cosubstituted with nitrogen and fluorine.

TiO2 (anatase) codoped with nitrogen and fluorine, synthesized by a simple solid state route, using urea and ammonium fluoride as sources of nitrogen and fluorine, respectively, as well as by decomposition of (NH4)2TiF6 for comparison, has been characterized by various techniques. XPS analysis shows the composition to be TiO1.7N0.18F0.12 for urea-based method (N, F-TiO2-urea) and TiO1.9N0.04F0.06 for complex decomposition method (N, F-TiO2-complex). Both the materials are defect-free as revealed by photoluminescence spectroscopy. Thus, N, F-TiO2-urea exhibits smaller defect-induced magnetization compared to the nitrogen-doped sample. Cosubstitution of N and F is accompanied with an enhancement of the absorption of light in the visible region giving rise to yellow color and with a band gap of ∼2.2 eV in the case of N, F-TiO2-urea. It exhibits enhanced photocatalytic activity and also significant hydrogen evolution (400 µmol/g) on interaction with visible light in the absence of any cocatalyst, which is much higher compared to N, F-TiO2-complex and N-TiO2. First-principles calculations show significant local distortions on codoping TiO2 with N and F and a lowering of energy by 1.93 eV per N, F pair. With virtual negative and positive charges on nitrogen and fluorine, respectively, the dopants prefer pairwise clustering. Our calculations predict a reduction in the band gap in TiO2 cosubstituted with nitrogen and fluorine. The calculated band structure shows that nitrogen 2p states form a separate subband just above the valence band which is enhanced on incorporation of fluorine. Our calculations also indicate anomalous Born effective charges in N, F-TiO2 and predict enhanced photocatalytic activity on codoping of TiO2 by N and F.

Halogen Bond Induced Structural and Photophysical Properties Modification in Organic-Inorganic Hybrid Manganese Halides.

The role of halogen bonding in organic-inorganic hybrid (OIH) halides was seldom investigated despite its potential to enhance the stability of the compound. In this context, we have synthesized (2-methylbenzimidazolium)MnCl3(H2O)·H2O (compound 1) crystallizing in a monoclinic space group P21/c with a 1D infinite chain of edge shared Mn octahedra. In contrast, the chloro-substituted derivative (5-chloro-2-methylbenzimidazolium)2MnCl4 (compound 2) exhibits 0D Mn tetrahedra with a triclinic P1̅ structure. This structural modification from 1D Mn octahedra to 0D Mn tetrahedra involves a unique type-II halogen bonding between organic chlorine (C-Cl) and inorganic chloride (Cl-Mn) ions. Compound 1 exhibits red emission, whereas compound 2 demonstrates dual-band emission, resulting from energy transfer from the organic amine to Mn centers. To rationalize this interesting modulation in structure and photophysical properties, the role of halogen bonding is explored in terms of quantitative electron density analysis and intermolecular interaction energies.

Photophysical Properties of S = 5/2 Zigzag-1D (2-Bromoethylammonium)3MnBr5 Antiferromagnet.

It has been challenging to design multifunctional lead-free organic-inorganic hybrid halides that can exhibit fascinating magnetic and photoluminescence properties since the dimensionality of the compounds has a contrasting impact on them. In this context, our newly synthesized compound (2-bromoethylammonium)3MnBr5 (BEAMBr) crystallizes in the monoclinic C2/c space group with corner-sharing zigzag 1D chains of MnBr6 distorted octahedra. Intriguingly, it exhibits a long-range antiferromagnetic ordering at low temperature (∼2.5 K) along with a typical low-dimensional broad magnetic susceptibility hump. The magnetic properties modeled by the exact diagonalization approach indicate strong intrachain and weak interchain interactions with J1 = -50.1 K, J2 = -13.0 K, and J' = -1.25 K, respectively, suggesting excellent one-dimensionality. In addition, BEAMBr displays orange-red emission with a photoluminescence quantum yield of 15.2%. Interestingly, electron-phonon coupling was observed in this soft distorted compound with coupling strength γLO = 128.3 meV, confirmed from the analysis of temperature-dependent emission line width broadening and Raman spectra.

High-pressure synthesis and magnetic properties of tetragonal R2BaCuO5 (R = Sm and Eu).

We report the experimental discovery of a new structural phase of well-known orthorhombic R 2BaCuO5 (R = Sm and Eu), exhibiting a tetragonal crystal structure with space group P4∕mbm. The high-pressure tetragonal phase is isostructural with the brown phase R 2BaCuO5 (R = La, Pr, and Nd). In this structure, the Cu ions form an isolated square planar environment, contrary to the orthorhombic phase, where the Cu ions are located in a distorted square pyramid. Magnetization and specific heat measurements reveal the long-range antiferromagnetic order of the Cu2+ and/or Sm3+ moments for the Sm-sample, with the magnetic specific heat accounting for only 35% of the magnetic entropy. Interestingly, the Eu-sample remains paramagnetic down to the lowest temperature. The high Curie-Weiss temperature of -140 K and magnetic entropy of 3% of the expected value indicates that the system is highly frustrated. We estimated the isothermal entropy change and investigated the magnetocaloric effect for Eu2BaCuO5, and the maximum entropy change detected at a field of 70 kOe at 3 K reaches 5.6 J kg-1K-1.

Near-room-temperature colossal magnetodielectricity and multiglass properties in partially disordered La2NiMnO6.

We report magnetic, dielectric, and magnetodielectric responses of the pure monoclinic bulk phase of partially disordered La2NiMnO6, exhibiting a spectrum of unusual properties and establish that this compound is an intrinsically multiglass system with a large magnetodielectric coupling (8%-20%) over a wide range of temperatures (150-300 K). Specifically, our results establish a unique way to obtain colossal magnetodielectricity, independent of any striction effects, by engineering the asymmetric hopping contribution to the dielectric constant via the tuning of the relative-spin orientations between neighboring magnetic ions in a transition-metal oxide system. We discuss the role of antisite (Ni-Mn) disorder in emergence of these unusual properties.

Inhibitory effect of Terminalia chebula Retz. fruit extracts on digestive enzyme related to diabetes and oxidative stress.

Terminalia chebula fruit extracts were prepared sequentially with hexane, ethyl acetate, methanol and methanol-water (70:30) and tested for their α-glucosidase inhibitory and antioxidant potential. The study resulted in the formulation of an extract with high α-glucosidase inhibitory potential (IC(50) 0.19 ± 0.03 µg mL(-1)) enriched with hydrolysable tannins. Also, each of the extract was chemically characterized by reversed-phase high-performance liquid chromatography on the basis of their marker compounds chebulagic acid, chebulinic acid and corilagin in order to give explanation to the significant activity shown by the extracts. The antioxidant potential of the highly active extract was evaluated in the cellular level also using superoxide dismutase, glutathione S-transferase and induced oxidative stress assays. The results indicated the possibility of using the extract as a nutraceutical health supplement in the management of type 2 diabetes.