Search

Mechanochemical synthesis of K2SbF5 by the successive grinding reactions of antimony (III) acetate with ammonium fluoride and potassium fluoride has been carried out. Powder X-ray diffraction pattern of K2SbF5 was refined successfully in orthorhombic space group (Cmcm) with a = 6.3214 (29) A, b = 13.9380 (60) A and c = 6.5817 (28) A. Finger print vibrations of SbF52− units in the sample have also been confirmed from FT-IR and Raman spectra. 5 mol% of Eu, Tb and Er doped K2SbF5 have been synthesized by the same method and their optical properties have been analyzed. The Judd-Ofelt (J-O) parameter (ΩJ) analyses of Eu doped samples have been carried out. On irradiating Er3+ doped sample with 980 nm laser, a bright green emission visible to the naked eye was evident. The decay times of these emissions have been estimated. Following a similar procedure, Rb2SbF5 has been synthesized for the first time.

Background and aimPreterm birth is one of the major cause of neonatal death in the developing countries and environmental factors are playing vital role in pre term birth. Nowadays Machine learning techniques are very useful for finding the hidden factors and classifications. The purpose of this study is to illustrate the importance of machine learning classification models and to identify the significant environmental factors behind pre-term birth.MethodWe have used 90 pregnant mothers, of whom 40 are preterm and 50 are full-term births. We have checked the model accuracy of the dataset through logistic regression and decision tree classifier model.ResultsThe comparative outcome of the logistic and decision tree model reveals that logistic regression is stronger in terms of metrics (precision = 0.92, F1-score = 0.96 and AUROC = 0.97), while the weak result shows by the decision tree (precision = 0.75, F1-score = 0.86 and AUROC = 0.87).ConclusionsThe conclusion shows that logistic regression is more appropriate as compare to decision tree classification model in the preterm birth data. The most influential factors for preterm birth are variables like α -HCH, total HCH and MDA (Malondialdehyde).

Rb2CoF6 was obtained from cubic perovskite RbCoF3 by a simple oxidation with H2O2 and characterized by powder X-ray diffraction, FT-IR, Raman, UV-visible spectroscopy measurements. It exhibited ferromagnetic behavior in the field range of ±1 kOe at room temperature with a coercivity of 123.6 Oe. Oxidation of phenol to benzoquinone was catalyzed by Rb2CoF6.

Simple shaking of tetragonal perovskite structured KCuF3 with H2O2 resulted in its transformation to cryolite structure as verified from indexing all the diffracted peaks in the powder X-ray diffraction pattern in a cubic unit cell with a = 8.1253 (33) A. Square morphology of the crystallites was noticed in FE-SEM image. The observed bands in FT-IR and Raman spectra could be finger printed to the positions reported for cubic cryolite structure. Elemental composition was confirmed by combining the results from inductively coupled plasma emission spectroscopy, X-ray photoelectron spectroscopy (XPS) and fluoride-ion selective electrode experiments. The existence of copper in +3 oxidation state in the sample has been confirmed from the observance of peaks with binding energies 932.2, 934.4, 951.6 and 954.4 eV in the core level XPS spectrum of Cu 2p3/2. Intense band at 223 and 280 nm followed by a broad band in the visible region in the UV–visible spectrum was noticed for K3CuF6 originating from ligand to metal charge transfer and d-d transitions of Cu3+, respectively. A similar transformation from RbCuF3 to cubic Rb3CuF6 was noticed. Use of K3CuF6 as catalyst for the photodegradation of aqueous rhodamine-6G dye solution has been demonstrated.

With the dual objective of investigating the site preferences of larger sized activator ions and to append luminescence property to the perovskite structured RbZnF3, doping of manganese(II), cerium(III), europium(III) and terbium(III) ions (5 mol%) was carried out. Although cubic symmetry of RbZnF3 was preserved for all the doped samples, site preference of rare-earth ions for the A-site Rb+ leading to an inverse perovskite arrangement has been noticed from careful analysis of lattice parameters from refinement of powder X-ray diffraction data. Undoped RbZnF3 exhibited rod-like morphology in the transmission electron microscopic image. In addition to an intense band around 230 nm assignable to the charge transfer from ZnF3- to Rb+, typical transitions of respective dopant ions were observed in their UV-visible spectra. The doped samples showed luminescence in blue, green and red regions and time decay experiments suggested uniform dispersion of them without any clustering effect. The lower phonon energy of RbZnF3 matrix by virtue of the presence of heavier rubidium at the A-site together with its doping with rare-earth ions resulting in an inverse perovskite like arrangement could favour their utility in various practical applications.

In many organizations and institutions, the use of cloud has increased rapidly. Cloud data storage is one of the main advantages of cloud computing, where the data owners do not store their data on own servers, but the data are mainly stored on the cloud by the data owners. On this end, cloud security is one of the most analytical aspects due to the confidential information and responsive data. This paper presents a new security framework which provides more data security and confidentiality. In the new security framework, a data is spilt in the blocks of bits. Genetic algorithm is applied on every two blocks of bits. Final output of every genetic algorithm operation is a ciphertext which is also two blocks of bits. Each ciphertext is stored on cloud at distinct location and location of the ciphertext is not fixed. So, it is difficult for an attacker to detect where ciphertext is. Also, genetic algorithm has no key concept due to which security of data increases. The new security framework applies genetic algorithm on smaller block size which increases the security. The framework also uses the capability list for secure and fine grain access of data.

A non-aqueous wet-chemical method has been developed for the haloperovskite, K3GaF6. The powder X-ray diffractogram of the sample was fitted by Rietveld refinement with a lattice constant, a = 8.5285 (10) A (space group Fm 3 ¯ m). Ga-F stretching mode was observed at 497 cm−1 in the FTIR spectrum. In the 19F NMR spectrum, signals at 153 and 180 ppm confirmed the presence of GaF6 octahedral units in the structure. The ligand-to-metal charge transfer (LMCT) transition appeared at 290 nm in the UV–vis absorbance spectrum generated by converting the reflectance data using Kubelka-Munk function. Following this success, K3GaF6 samples doped with 3 mol% of Eu3+, Er3+, Tb3+ and Er3+(2 mol%); Yb3+ (1 mol% co-doped) were prepared. Intra configurational f-f transitions in the UV–vis absorption spectrum were evident only for Er3+doped samples. Normal emissions (Stokes emission) in red, green regions arising from Eu3+, Tb3+ and Er3+ were observed in their photoluminescence spectra. Upconverted emissions of Er3+ and Er3+:Yb3+in the green and red regions were observed on exciting doped samples with laser of λ = 980 nm as confirmed from the corresponding CIE plots. The number of photons involved in the upconversion process was determined along with the estimation of decay time for the emission from Er3+:Yb3+ co-doped sample. A composite of Er3+;Yb3+ co-doped sample with optically transparent polymer, PMMA was fabricated and it exhibited uniform green glow after illuminating it with 980 nm laser.

Gender classification is important for study of gender ratio, in security and forensic fields. There are several bases biometric, hand writing, palm pattern, ear shape and skin patches on which human gender is classified. In this paper, we use the skin patches of different body parts such as forehead, cheeks and opposite side of palm to classify the gender. If, criminals have covered their face in that case also, we can classify and detect their gender by using the skin patches of opposite side of palm. Since we use skin patches of different body parts, accuracy and probability to classify the gender has increased. By taking skin patches of different body parts as input and results, we find that our approach is novel and efficient.

The extent of incorporation of Cu2+for Zn2+ in layered zinc hydroxide acetate to convert it to a hydroxy double salt carried out following titrimetric experiments with KOH solution. The reflections present in the powder X-ray diffraction pattern became broad suggestive of incorporation of copper for zinc. Well defined weight-loss steps, in the thermogravimetric trace of zinc hydroxide acetate, became diffused with the inclusion of copper. The intercalation of various polyols (ethylene glycol, diethylene glycol, and propylene glycol)was performed successfully, exploiting the organophilic character of Zn Cu hydroxide acetate. The interlayer spacing expanded for polyol intercalated samples, as indicated by their powder X-ray diffraction patterns.The FT-IR and Raman spectra of polyol intercalated samples confirmed their presence in the interlayer, and the samples showed enhancement in thermal stability. These samples showed mesoporosity and reasonably high surface area (128.6 m2/g). The role of ethylene glycol intercalated Zn Cu hydroxy double salt as an adsorbent to remove harmful and carcinogenic CR dye molecules from aqueous solutions investigated. The physisorption process was majorly responsible for the effective removal of CR dye, following a pseudo-second-order kinetics.

Reaction of rare earth acetylacetonates with rubidium fluoride in methanol medium at room temperature produced crystalline phases and they were characterized using various analytical techniques. Fluorite structured products with RbREF4 stoichiometry were obtained for RE = Pr, Nd, Sm, Eu and Tb as revealed from their powder X-ray diffraction (PXRD) patterns, and wet chemical analysis. RbRE2F7 crystallizing in orthorhombic symmetry resulted for the rare earths from Dy to Yb as illustrated by their PXRD patterns, HR-TEM and selected area electron diffraction (SAED) techniques. While cubic RbPrF4 showed three phonon modes at 197, 281 and 324 cm−1, orthorhombic RbEr2F7 exhibited 10 modes at 128, 191, 236, 277, 341, 435, 520, 587, 642 and 726 cm−1, respectively in its Raman spectrum at room temperature. Optical transitions arising from the f-shell of the rare earth ions have been observed in UV–visible and photoluminescence spectra and analyzed.