Photocatalytic Generation of Divalent Lanthanide Reducing Agents.

Divalent lanthanide (Ln) compounds are excellent reducing agents with unique reactivity profiles. These reagents are typically used in superstoichiometric amounts, often in combination with harmful additives. Reactions catalytic in Ln(II) reagents that retain the reactivity and selectivity of the stoichiometric transformations are currently lacking due to the absence of effective and selective methods to form reactive Ln(II) species from stable precursors. Here, active Ln(II) is generated from a Ln(III) precursor through reduction by a photoexcited coumarin or carbostyril chromophore, which, in turn, is regenerated by a sacrificial reductant. The reductant can be metallic (Zn) or organic (amines) and can be used in strictly stoichiometric amounts. A broad range of reactions, including C-halogen, C═C, C═X (X = O, N), P═O, and N═N reductions, as well as C-C, C-X (X = N, S, P), and N-N couplings were readily carried out in yields and selectivities comparable to or better than those afforded by the analogous stoichiometric transformations. The reaction outcomes could be altered by changing the ligand or the lanthanide or through the addition of environmentally benign additives (e.g., water). EPR spectroscopy supported the formation of both Ln(II) and oxidized chromophore intermediates. Taken together, these results establish photochemical Ln(II) generation as a powerful strategy for rendering Ln(II)-mediated reactions catalytic.

Realization of a DNA biosensor using inverted Lamb wave MEMS resonator based on ZnO/SiO2/Si/ZnO membrane.

A novel technique based on inverted Lamb wave MEMS resonator has been exploited for the realization of a DNA biosensor. Zinc oxide based Lamb wave MEMS resonator in the inverted configuration of ZnO/SiO2/Si/ZnO is fabricated for label free and efficient detection of Neisseria meningitidis, responsible for bacterial meningitis. Meningitis remains a devastating endemic in sub-Saharan Africa. Its early detection can prevent the spread and its lethal complications. The developed biosensor shows a very high sensitivity of 310 Hz(ngµl-1)-1 and very low detection limit of 82 pgµl-1 for symmetric mode of the Lamb wave device while the antisymmetric mode shows a sensitivity of 202 Hz(ngµl-1)-1 and the limit of detection of 84 pgµl-1. This very high sensitivity and very low detection limit of the Lamb wave resonator can be attributed to very high mass loading effect on the membranous structure of Lamb wave device, unlike the bulk substrate based devices. The indigenously developed MEMS based inverted Lamb wave biosensor shows high selectivity, long shelf life and good reproducibility. The ease of operation, low processing time and possibility of wireless integration of the of the Lamb wave DNA sensor paves a path towards the promising application in the field of meningitidis detection. The use of fabricated biosensor can be extended to other viral and bacterial detection applications as well.

Theoretical insight of origin of Rashba-Dresselhaus effect in tetragonal and rhombohedral phases of BiFeO3.

The inclusion of the spin-orbit coupling effect in ferroelectric materials with non-centrosymmetry leads to intriguing properties for spintronic applications. In the present work, a comparative study of spin splitting in the bulk electronic energy bands of the tetragonal and rhombohedral phases of BiFeO3 (BFO) in terms of the Rashba and Dresselhaus effects is carried out through first-principles calculations. The obtained spin splittings, particularly at the conduction band minima, are further supplemented with an effective k·p model analysis. For the tetragonal BFO, a dominating pure bulk-type Rashba effect with helical in-plane spin components shown through diagrams is observed, whereas the rhombohedral BFO shows a significant contribution from the out-of-plane spin components and an interplay between the Rashba and Dresselhaus effects is discussed. In addition, tunability of the Rashba parameters with the application of uniaxial strain (±5%) is obtained in tetragonal BFO, in which the Rashba coefficient (αR) doubles with a compressive 5% strain, making tetragonal BFO a suitable candidate for spintronic applications. More importantly, full reversal of the in-plane spin texture is obtained for the opposite polarization states in tetragonal BFO with an activation energy barrier of 1.13 eV.

Sensitization Pathways in NIR-Emitting Yb(III) Complexes Bearing 0, +1, +2, or +3 Charges.

Yb(III) complexes of macrocyclic ligands based on 1,4,7,10-tetraazacyclododecane were synthesized. The ligands carried a carbostyril chromophore for Yb(III) sensitization, and carboxylate or carbamide donors for metal binding, forming complexes of 0, +1, +2, or +3 overall charge. The coordination geometry was little affected by the replacement of carboxylates with amides, as shown by paramagnetic 1H NMR spectroscopy. The Yb(III)/Yb(II) reduction potentials were dependent on the nature of the metal binding site, and the more positively charged complexes were easier to reduce. Carbostyril excitation resulted in Yb(III) luminescence in every complex. The residual carbostyril fluorescence quantum yields were smaller in complexes containing more reducible Yb(III) centers decreasing from 5.9% for uncharged complexes to 3.1-4.4% in +3 charged species, suggesting photoinduced electron transfer (PeT) from the antenna to the Yb(III). The relative Yb(III) luminescence quantum yields were identical within the experimental error, except for the +3 charged complex with fully methylated coordinating amides, which was the most intense Yb(III) emitter of the series in water. Quenching of the Yb(III) excited state by NH vibrations proved to limit Yb(III) emission. No clear improvement of the Yb(III) sensitization efficiency was shown upon faster PeT. This result can be explained by the concomitant sensitization of Yb(III) by phonon-assisted energy transfer (PAEnT) from the antenna triplet excited state, which was completely quenched in all of the Yb complexes. Depopulation of the triplet by PeT quenching of the donor singlet excited state would be compensated by the sensitizing nature of the PeT pathway, thus resulting in a constant overall sensitization efficiency across the series.

Microfluidics integrated NiO based electrolyte-gated FETs for the detection of cortisol.

Field effect transistors (FETs) have emerged to be an attractive platform for the accurate and rapid detection of biological moieties. The gating effect in a FET when applied through an electrolyte further improves the device sensitivity and response time. The present work involves two aspects for devising an electrolyte-gated FET (EGFET) based platform for the detection of cortisol. The former involves optimization of the semiconducting channel dimensions and its deposition parameters to achieve maximum sensitivity of the device. Afterwards, the optimized device has been integrated with appropriate microfluidic channels for reliable and rapid detection using low sample volumes. A nickel oxide (NiO) thin film has been used as a semiconducting channel and sensing layer. The device has been electrically and structurally characterized and the cortisol sensing performance has been analyzed by binding cortisol antibodies to NiO covalently. A microfluidic system has been optimized for analyte delivery. High sensitivity in a wide linear range of cortisol antigen concentrations from 1 fg mL-1 to 1 µg mL-1 with a low detection limit of 0.5 fg mL-1 and a stability of 7 weeks shows the applicability of the devised structure for point-of-care applications. The final device structure has been analyzed on real saliva samples and the results are found to be in good agreement with the standard ELISA.

Improved emission of Yb(III) ions in triazacyclononane-based macrocyclic ligands compared to cyclen-based ones.

Yb(III) complexes based on ligands with a 1,4,7-triazacyclononane (tacn) macrocyclic core were synthesised. The complexes carry a 4-methoxymethyl-substituted carbostyril chromophore that serves as a light-harvesting antenna. The ligands supply 5 nitrogen and 3 oxygen donors via 1 methylenecarboxamide and 2 picolinate donors, creating +1 charged complexes with an octadentate binding environment. The electronic properties of the picolinates are modulated by varying the substitution at the 4 position with OMe, H, Cl, or CF3. Cyclic voltammetry indicated that the tacn-based Yb(III) complexes were easier to reduce than the analogous cyclen complexes. The first reductive event is likely picolinate-centred, followed by the formation of further reduced species. Antenna excitation yielded Yb(III) luminescence in the near-infrared (NIR) region in all cases. The antenna photophysical properties were consistent with intraligand photoinduced electron transfer from the excited carbostyril to the picolinate groups. The relative quantum yields of Yb(III) luminescence were determined. The lowest value was obtained for the complex with the most efficient antenna-to-picolinate photoinduced electron transfer. Despite intraligand electron transfer quenching of the antenna, the tacn-based Yb complexes were more emissive than their cyclen analogues, highlighting the influence of the ligand structure on the luminescence properties of NIR emissive lanthanide(III) ions.

Smartphone integrated handheld Long Range Surface Plasmon Resonance based fiber-optic biosensor with tunable SiO2 sensing matrix.

In the present work, a novel smartphone assisted fiber optic (FO)-Long range surface plasmon resonance (LRSPR) based biosensor is proposed. In the developed biosensor, the inbuilt color sensitive property of the digital camera present in the smartphone is used for the monitoring of blue and red color channel intensities. This will replace the most exploited diffraction gratings or narrow band filters used for analyzing the spectral data in reported smartphone based SPR sensors. The proposed technique helps in improving the sensitivity and reduces the chances of wrong detection. For the first time, SiO2 nanostructured film is employed as the dielectric sensing layer to excite the Long range surface plasmons (LRSPs) in the dielectric-metal-dielectric configuration. The proposed FO-LRSPR biosensor possess limit of detection of 0.02 mM and sensitivity of 0.9/mM and, for uric acid detection in the 0.1 mM-1 mM concentration range. The novel fabricated sensor which is found to be stable up to 24 weeks can be effectively utilized in health sector and environment monitoring and it possess the ability of point-of-care detection, even in rural and remote areas.

NO2 Gas Sensor Based on SnSe/SnSe2p-n Hetrojunction.

Air pollution is a big concern as it causes harm to human health as well as environment. NO2 can cause several respiratory diseases even in low concentration and therefore an efficient sensor for detecting NO2 at room temperature has become one of the priorities of the scientific community. Although two dimensional (2D) materials (MoS2 etc.) have shown potential for NO2 sensing at lower temperatures, but these have poor desorption kinetics. However, these limitations posed by slow desorption can be overcome, if a material in the form of a p-n junction can be suitably employed. In this work, ~150 nm thick SnSe2 thin film has been deposited by thermally evaporating in-house made SnSe2 powder. The film has been studied for its morphological, structural and gas sensing applications. The morphology of the film showed that the film consists of interconnected nanostructures. Detailed Raman studies further revealed that SnSe2 film had 31% SnSe. The SnSe-SnSe2 nanostructured sensor showed a response of ~112% towards 5 ppm NO2 at room temperature (30 °C). The response and recovery times were ~15 seconds and 10 seconds, respectively. Limit of detection for NO2 was in sub-parts per million (sub-ppm) range. The device demonstrated a better response towards NO2 compared to NH3, CH4, and H2. The mechanism of room temperature fast response, recovery and selective detection of NO2 independent of humidity conditions has been discussed based on physisorption, charge transfer, and formation of SnSe-SnSe2 (p-n) nano-junctions. Depositing a nanostructured film consisting of nano-junctions using an industrially viable thermal evaporation technique for sensing a very low concentration of NO2 is the novelty of this work.

Arabidopsis bZIP11 Is a Susceptibility Factor During Pseudomonas syringae Infection.

The induction of plant nutrient secretion systems is critical for successful pathogen infection. Some bacterial pathogens (e.g., Xanthomonas spp.) use transcription activator-like (TAL) effectors to induce transcription of SWEET sucrose efflux transporters. Pseudomonas syringae pv. tomato strain DC3000 lacks TAL effectors yet is able to induce multiple SWEETs in Arabidopsis thaliana by unknown mechanisms. Because bacteria require other nutrients in addition to sugars for efficient reproduction, we hypothesized that Pseudomonas spp. may depend on host transcription factors involved in secretory programs to increase access to essential nutrients. Bioinformatic analyses identified the Arabidopsis basic-leucine zipper transcription factor bZIP11 as a potential regulator of nutrient transporters, including SWEETs and UmamiT amino acid transporters. Inducible downregulation of bZIP11 expression in Arabidopsis resulted in reduced growth of P. syringae pv. tomato strain DC3000, whereas inducible overexpression of bZIP11 resulted in increased bacterial growth, supporting the hypothesis that bZIP11-regulated transcription programs are essential for maximal pathogen titer in leaves. Our data are consistent with a model in which a pathogen alters host transcription factor expression upstream of secretory transcription networks to promote nutrient efflux from host cells.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Possible competitive modes of decarboxylation in the annulation reactions of ortho-substituted anilines and arylglyoxylates.

Annulation reactions of ortho-substituted anilines and arylglyoxylates in the presence of K2S2O8 at 80 °C under metal-free neutral conditions have been investigated, which extended a platform for the tandem synthesis of nitrogen heterocycles. While arylglyoxylic acids are known to undergo decarboxylation to form an acyl radical in the presence of K2S2O8 and used in the Minisci acylation of electron-deficient (hetero)aromatics, their reactions with electron-rich ortho-substituted anilines to form nitrogen heterocycles have recently been studied. Depending upon the experimental conditions used in the reactions, the mechanism of the formation of heterocycles involving reactions of an acyl radical or aryl iminocarboxylic acids has been postulated. Given the subtle understanding of the mechanisms of annulation reactions of 2-substituted anilines and arylglyoxylates in the presence of K2S2O8, an extensive mechanistic investigation was undertaken. In the current study, the various mechanistic pathways including the generation of acyl, imidoyl, aminal, and N,O-hemiketal radicals have been postulated based on different possible decarboxylation modes. Some of the proposed intermediates are supported based on the available analytical data. The protocol uses a single, inexpensive reagent K2S2O8, which offers not only transition-metal-free conditions but also serves as the reagent for the key decarboxylation step. Taken together, this study complements the current development of the annulation reactions of 2-substituted anilines and arylglyoxylates in terms of synthesis and mechanistic understanding.

Refractive index tuning of SiO2 for Long Range Surface Plasmon Resonance based biosensor.

A novel, highly sensitive and low cost Long Range Surface Plasmon Resonance (LRSPR) biosensor for detecting uric acid, as a model analyte, has been developed in this work. Silicon dioxide (SiO2) having low and tunable refractive index has been chosen as the dielectric layer for the excitation of LRSP modes replacing the most explored Cytop and Teflon polymers. The prepared LRSPR based uric acid bio-sensor gives good response characteristics with a high sensitivity of about 21.6°/mM and low limit of detection (LOD) of 0.02 mM. The fabricated LRSPR sensor was also evaluated to detect uric acid in real serum samples. The results yield a great scope to promote the development of robust, efficient and highly selective LRSPR based biosensors with SiO2 as tunable dielectric layer.

Molybdenum Disulfide-Wrapped Carbon Nanotube-Reduced Graphene Oxide (CNT/MoS2-rGO) Nanohybrids for Excellent and Fast Removal of Electromagnetic Interference Pollution.

Electromagnetic interference (EMI) pollution has now become a subject of great concern with the rapid development of delicate electronic equipment in commercial, civil, and military operations. There has been a surge in pursuit of light-weight, adaptable, effective, and efficient EMI screening materials in recent years. The present article addresses a simple and sensitive approach to synthesize a core/shell carbon nanotube/MoS2 heterostructure supported on reduced graphene oxide (CNT/MoS2-rGO nanohybrid) as an efficient electromagnetic shielding material. The structural and morphological characteristics were accessed through X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy, augmenting successful formation of the CNT/MoS2-rGO nanohybrid. The shielding performance of the as-synthesized samples has been accessed in a wide frequency range of 8-12 GHz. A CNT/MoS2-rGO nanohybrid demonstrates a better EMI shielding performance in comparison to MoS2 nanosheets and MoS2-rGO nanohybrid individually. The CNT/MoS2-rGO nanohybrid having a thickness ∼1 mm shows excellent total shielding effectiveness (SET) as high as 40 dB, whereas MoS2 and MoS2-rGO hybrid lags far, with the average value of SET as 7 and 28 dB, respectively. It also demonstrates that the nanohybrid CNT/MoS2-rGO shields the EM radiation by means of absorption through several functional defects and multiple interfaces present in the heterostructure. Herein, we envision that our results provide a simple and innovative approach to synthesize the light-weight CNT/MoS2-rGO nanohybrid having flexibility and high shielding efficiency and widen its practical applications in stealth technology.

The role of an unintentional carbon dopant in resolving the controversial conductivity aspects in BiFeO3.

Light elements like carbon may enter unintentionally into a material during material processing owing to their ubiquitous nature, and may significantly influence its observed electronic and magnetic properties. In the present work, the energetics and kinetics of carbon impurity related defects in BiFeO3 (BFO) are studied using first principles calculations in order to gain insight into the ongoing controversial aspects of conductivity of BFO. The results suggest that oxygen deficient conditions provide a favorable chemical environment for incorporation of carbon in BFO. Calculations based on the formation energy predict that carbon can spontaneously occupy interstitials, O, and Fe sites in BFO (where it is found to introduce impurity induced shallow acceptor type states at an energy of 0.05 eV above the valence band maximum). Carbon occupying cationic sites (CBi and CFe) tends to ionize their vacancies (VBi and VFe), resulting in the formation of a CO3 cluster, whereas it induces localized electron traps with energy levels composed of impurity states near the center of the band gap (0.9 eV above the valence band maximum) when occupying interstitial sites in BFO. An understanding of the migration of C impurity in BFO is developed, which suggests the favorable incorporation of carbon impurity via a vacancy mechanism. In order to confirm the theoretical results, experimental studies are carried out where BFO and carbon doped BFO (BCFO) thin films are grown by the pulsed laser deposition technique. Polycrystalline pure phase (R3c) thin films of BFO and BCFO are obtained. The presence of defect states in the deposited thin films is optically analyzed by the photoluminescence (PL) technique. In order to highlight the critical role of carbon in modifying the electrical conductivity of BFO, a BCFO/BFO/ITO based p-i-n heterojunction is prepared. The electrical characteristics depict remarkable rectifying characteristics, thus suggesting the p-type nature of carbon dopant in otherwise intrinsic BFO.

CdSe/V2O5 core/shell quantum dots decorated reduced graphene oxide nanocomposite for high-performance electromagnetic interference shielding application.

The present work reports nanocomposite of CdSe/V2O5 core-shell quantum dots with reduced graphene oxide (rGO-V-CdSe), as an efficient lightweight electromagnetic wave shielding material, synthesized by a simplistic solvothermal approach. The as-synthesized nanocomposite was analyzed for its structural, compositional and morphological features by x-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy and x-ray photoelectron spectroscopy (XPS). The measurement of complex permittivity/permeability and total shielding efficiency of the as-synthesized samples has been done in a wide frequency range of 8-12 GHz (X-band). Compared to rGO and rGO-CdSe, rGO-V-CdSe nanocomposite exhibits significantly enhanced EMI shielding properties in terms of both dielectric loss and total shielding SE T . The high value of real permittivity (average ε'∼70) and the overall shielding effectiveness up to ∼38 dB have been recorded for rGO-V-CdSe nanocomposite. The studies also infer that the absorption contributes more in total shielding than reflection. The high value of dielectric loss and shielding effectiveness could also be attributed to the presence of various defects leading to dipolar and interfacial polarizations. The excellent EMI shielding properties of the nanocomposite in GHz frequency range (X-band) pave an intuitive way for fabricating a versatile EMI shielding nanocomposite material for applications.

Rapid antibiotic susceptibility testing by resazurin using thin film platinum as a bio-electrode.

Traditional antibiotic susceptibility testing methods take several days to confirm and start disease treatment. The lack of new antibiotics or drugs warrants a need for optimization of current diagnostic tools for immediate antibiotic susceptibility testing. We present a rapid screening method to evaluate the response of bacteria to antibiotics based upon the electrochemical measurement of live bacterial cell metabolic activity using an electroactive redox dye, resazurin. A thin film of Pt deposited over a glass substrate using the direct current sputtering technique was used as a working bio-electrode for electrochemical readouts. X-ray diffraction and scanning electron microscopy was carried out to characterize the Pt thin film. We tested the efficacy of the method using two different strains, Klebsiella pneumoniae (ATCC-700603) and Escherichia coli (ATCC-25922), against ampicillin, kanamycin and tetracycline. The dye, on incubation with viable bacteria, undergoes reduction and lowers the corresponding peak current value. However, in the presence of an effective antibacterial agent, reduction did not occur due to bacterial cell death and absence of a reducing environment. The electrochemical changes in peak current values were monitored using the differential pulse voltammetry technique and interpretation of the results obtained was based upon changes in peak current values. Our results depict a new methodology where a concentration of 104 cells/mL cells can be detected in less than 4 h. The results were also compared with the conventional disc diffusion method for susceptibility testing which has a bacterial incubation time of 18-24 h. The method can potentially be used for monitoring the susceptibility of bacterial strains towards existing antibacterial agents in an easy, rapid, reliable and inexpensive manner without any pre-cultivation of bacteria.

Fabrication and characterization of ZnO-TiO2-PANI (ZTP) micro/nanoballs for the detection of flammable and toxic gases.

The present paper reports the in-situ chemical polymerization of nanocomposites thin film composed by titanium dioxide (TiO2), zinc oxide (ZnO) and polyaniline (PANI). It was found that nanocomposites sensor is highly selective and shows response to low concentration. To improve the sensing response characteristics of ZT thin film, PANI is incorporated. Thin film based LPG sensor of ZnO-TiO2-PANI composite was fabricated by spin coating of ZnO-TiO2 nanoparticles doped with PANI over inter digital electrodes (IDEs). The thin film was characterized by using XRD, SEM, TEM, UV-vis, BET and FTIR. It was also tested for gas sensing properties of LPG/NO2 which are well known flammable and toxic gases. The measured response for ZnO-TiO2-PANI based sensor was 87 for 2000 ppm of LPG and 412 for 20 ppm of NO2 at room temperature towards other testing gases together with Acetone, IPA, NH3 and CO2.

CoFe2O4 nanoparticles decorated MoS2-reduced graphene oxide nanocomposite for improved microwave absorption and shielding performance.

Magnetic CoFe2O4 nanoparticles decorated onto the surface of a MoS2-reduced graphene oxide (MoS2-rGO/CoFe2O4) nanocomposite were synthesized by a simple two-step hydrothermal method. The electromagnetic (EM) wave absorption performance and electromagnetic interference (EMI) shielding effectiveness of the materials were examined in the frequency range of 8.0-12.0 GHz (X-band). The MoS2-rGO/CoFe2O4 nanocomposite was characterized by various tools such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. High-resolution transmission electron microscopy results confirmed the decoration of magnetic nanoparticles onto the surface of the MoS2-rGO nanocomposite with a diameter of 8-12 nm. The multiple interfacial polarization, moderate impedance matching, and defect dipole polarization improve the dielectric and magnetic loss of the materials, which leads to strong attenuation loss ability of incident EM energy within the shield. The pure MoS2-rGO nanocomposite represents total shielding effectiveness (SET ∼16.52 dB), while the MoS2-rGO/CoFe2O4 nanocomposite exhibits total shielding effectiveness (SET ∼19.26 dB) over the entire frequency range. It may be explained that the magnetic nanoparticles (CoFe2O4) serve as excellent conductive and magnetic fillers with a large surface area, leading to the migration of charge carriers at multi-interfaces.

EMI shielding of ABS composites filled with different temperature-treated equal-quantity charcoals.

Acrylonitrile-butadiene-styrene (ABS) composites were prepared by dry mixing equal-quantity (20 wt%) charcoals treated at different temperatures followed by hot compression. Processing parameters were kept the same. Seven samples of the same charcoal were modified for carbonization at different temperatures varying from 500 °C to 1100 °C in steps of 100 °C. Temperature treatment of charcoal crafts an increase in the conductivity of ABS composites, primarily accountable for the enhancement of shielding. The electromagnetic shielding effectiveness in the X-band (8.2-12.4 GHz) has been discovered to significantly increase for composites with ascending temperature-treated charcoals. An abrupt increase in the conductivity of ABS composites containing equal quantities of charcoal subjected to enhanced temperature treatments truly explains the effective absorption behaviour. The composite containing 1100 °C temperature-treated charcoal shows absorption-dominated SE of ∼36.8 dB at 11.6 GHz. Dielectric behaviour proclaims a decrease in dielectric loss (ε'') with an increase in the frequency. Besides this, the increased carbonization temperatures also show increased porosity and high dielectric losses. The scanning electron microscopy studies validate the increase in the porosity of charcoals due to the increase in the treatment temperature. The results are promising for the development of custom-made shielding composites possessing equal quantities of charcoal treated at enhanced temperatures.

Insight into the gas phase dissociation of CF3CH2I and its reactions with H and OH by first principles.

The Arrhenius kinetic parameters of dissociation reactions and reactions of CF3CH2I with radicals like H, O, and OH are determined using highly accurate first principles calculations. Thermophysical properties like molar heat capacity (Cp), thermal stability index, and the bond dissociation energies are also determined for the CF3CH2I molecule under the PBE/DNP formalism. Since, there are no theoretical study or experimental investigation reports available regarding the dissociation reactions of CF3CH2I and reactions of this molecule with the H and OH radical, a parallel comparative analysis is done with similar iodoalkanes to ascertain the precision of the results obtained. The atmospheric lifetime of 0.54 years is obtained for this molecule.

Weak Antilocalization and Quantum Oscillations of Surface States in Topologically Nontrivial DyPdBi(110)Half Heusler alloy.

Recently, a number of ternary half-Heusler compounds have been predicted independently by several research groups as candidates for 3D topological insulators. In this work, we report the observation of a two-dimensional (2D) weak antilocalization (WAL) effect, one of the hall-marks of topological surface states, and Shubnikov-de Hass (SdH) quantum oscillations in <110> oriented DyPdBi (DPB) thin films grown on MgO (100) substrates. The films prepared by pulsed laser deposition technique under the optimized conditions, showed a textured structure with (110) planes parallel to the (100) plane of MgO. The measured WAL effect follows the Hikami-Larkin-Nagaoka (HLN) model and the extracted values of phase coherence length (lϕ) and α are ~420 nm and ~-0.52 respectively. The power law variation of lϕ (~T-0.46) indicates the presence of the 2D surface states in DPB film. The Dirac nature of the surface states is further confirmed by Landau-level fan diagram analysis of SdH oscillations of the magneto-transport data. This analysis shows a finite Berry phase of 0.90π ± 0.16, reasonably close to the expected π value. Sheet Carrier density, ns ~ 2.56 × 1012 cm-2, calculated from the SdH oscillations (fSdH ~ 106 T) and Hall measurements agree well with each other. These findings demonstrate that the half Heusler DPB thin films (~15-20 nm) can be used as a suitable material for investigating the novel intrinsic quantum transport properties of surface Dirac fermions.