Periodically Arranged Arrays of Dendritic Pt Nanospheres Using Cage‐Type Mesoporous Silica as a Hard Template

Dendritic Pt nanospheres of 20 nm diameter are synthesized by using a highly concentrated surfactant assembly within the large‐sized cage‐type mesopores of mesoporous silica (LP‐FDU‐12). After diluting the surfactant solution with ethanol, the lower viscosity leads to an improved penetration inside the mesopores. After Pt deposition followed by template removal, the arrangement of the Pt nanospheres is a replication from that of the mesopores in the original LP‐FDU‐12 template. Although it is well known that ordered LLCs can form on flat substrates, the confined space inside the mesopores hinders surfactant self‐organization. Therefore, the Pt nanospheres possess a dendritic porous structure over the entire area. The distortion observed in some nanospheres is attributed to the close proximity existing between neighboring cage‐type mesopores. This new type of nanoporous metal with a hierarchical architecture holds potential to enhance substance diffusivity/accessibility for further improvement of catalytic activity.     

An Efficient Variant of Fully-Convolutional Network for Segmenting Lung Fields from Chest Radiographs

Wireless Personal Communications - Automatic analysis of chest radiographs using computer-aided diagnosis (CAD) systems is pivotal to perform mass screening and detect early signs of various...     

Counting elliptic plane curves with fixed -invariant

The number of degree elliptic plane curves with fixed -invariant passing through general points in is computed.

     

A Novel Ensemble Method for PTB Classification in CXRs

Pulmonary tuberculosis (PTB) is a contagious disease that affects the lung region. PTB is a life-threatening disease if it is detected late or left untreated. To perform the initial screening of PTB, the World Health Organization has recommended chest radiograph. Till now, the screening process requires either the patients to come to secondary health centers from rural areas or the radiologists to go the remote locations. This process is rejuvenated with the introduction of computer-aided diagnosis (CAD) systems. CAD systems reduce the need for expert radiologists in the screening process. However, the development and deployment are still in the early phases as new methods are being developed to improve the performance of CAD systems in terms of accuracy, specificity and sensitivity. In this study, a deep learning-based PTB classification system has been presented that achieves the state-of-the-art performance for TB classification. Firstly, a proposed architecture based on the blocks is presented and then it is used to create an ensemble. In the proposed ensemble, two standard architectures namely AlexNet, and ResNet have also been used in addition to the proposed architecture. All the architectures are trained and evaluated on a combined dataset formed using publicly available standard datasets. The proposed ensemble attains the accuracy of 90.00% and area under the curve equal to 0.96, which is better than the performance of the existing methods.

     

A Simple Closed form Approximation of Average Channel Capacity for Weakly Turbulent Optical Wireless Links

Wireless Personal Communications - Performance of optical wireless link is degraded by the presence of atmospheric turbulence induced fading. In this paper, a simple tight closed form expression...     

Variable‐Temperature Powder X‐ray Diffraction of Aromatic Carboxylic Acid and Carboxamide Cocrystals

The effect of temperature on the cocrystallization of benzoic acid (BA), pentafluorobenzoic acid (FBA), benzamide (BAm), and pentafluorobenzamide (FBAm) is examined in the solid state. BA and FBA formed a 1:1 complex 1 at ambient temperature by grinding with a mortar and pestle. Grinding FBA and BAm together resulted in partial conversion into the 1:1 adduct 2 at 28 °C and complete transformation into the product cocrystal at 78 °C. Further heating (80–100 °C) and then cooling to room temperature gave a different powder pattern from that of 2 . BAm and FBAm hardly reacted at ambient temperature, but they afforded the 1:1 cocrystal 3 by melt cocrystallization at 110–115 °C. Both BA+FBAm ( 4 ) and BA+BAm ( 5 ) reacted to give new crystalline phases upon heating, but the structures of these products could not be determined owing to a lack of diffraction‐quality single crystals. The stronger COOH and CONH₂ hydrogen‐bonding groups of FBA and FBAm yielded the equimolar cocrystal 6 at room temperature, and heating of these solids to 90–100 °C gave a new crystalline phase. The X‐ray crystal structures of 1 , 2 , 3 , and 6 are sustained by the acid–acid/amide–amide homosynthons or acid–amide heterosynthon, with additional stabilization from phenyl–perfluorophenyl stacking in 1 and 3 . The temperature required for complete transformation into the cocrystal was monitored by in situ variable‐temperature powder X‐ray diffraction (VT‐PXRD), and formation of the cocrystal was confirmed by matching the experimental peak profile with the simulated diffraction pattern. The reactivity of H‐bonding groups and the temperature for cocrystallization are in good agreement with the donor and acceptor strengths of the COOH and CONH₂ groups. It was necessary to determine the exact temperature range for quantitative cocrystallization in each case because excessive heating caused undesirable phase transitions.     

Gauche and staggered forms of diethylamine in solvates of 1,5-dichloro-cis-9,10-diethynyl-9,10-dihydroanthracene-9,10-diol. A case of conformational pseudopolymorphism?

Diethylamine has been trapped in its less stable gauche conformation in a solvate of the title diol; the staggered conformation, which is ca. 4 kJ mol(-1) more stable, is found in another solvate of the same host.     

Sulphamic Acid （H2NSO3H）-Catalyzed Multicomponent Reaction of β-Naphthol： An Expeditious Synthesis of Amidoalkyl Naphthols

Sulphamic acid （H2NSO3H） was found to be an efficient catalyst for the multicomponent condensation reaction of β-naphthol, aromatic aldehydes and urea or amides to afford the corresponding α-amidoalkyl-β-naphthols in good yields. The remarkable features of this new procedure are high conversions, short reaction time, clean reaction profiles and simple experimental and work-up procedures.     

Chemoenzymatic route to macrocyclic hybrid peptide/polyketide-like molecules

Hybrid peptide-polyketides are a class of medically and biologically important natural products characterized by stereochemical and functional diversity. In their biosynthesis, hybrids are often macrocyclized to achieve rigid structures that populate bioactive conformations. We herein present a chemoenzymatic strategy to access the stereochemical and functional diversity found in macrocyclic hybrid natural products in a manner amenable to efficient library synthesis. Our method makes use of small building blocks in the form of Fmoc-protected epsilon-amino acids containing embedded polyketide functionality. The building block approach allows for combinatorial synthesis of linear molecules that can be activated as soluble thioesters or tethered to a solid-phase resin. We demonstrate that these linear molecules are substrates for macrocyclization by a tolerant catalyst, TycC TE, derived from a nonribosomal peptide synthetase. The method should allow for access to diverse structures with hybrid peptide-polyketide character that can be screened for improved or novel activities.     

Dual Photoredox/Nickel‐Catalyzed Three‐Component Carbofunctionalization of Alkenes

The potential of merging photoredox and nickel catalysis to perform multicomponent alkene difunctionalizations under visible‐light irradiation is demonstrated here. Secondary and tertiary alkyl groups, as well as sulfonyl moieties can be added to the terminal position of the double bond with simultaneous arylation of the internal carbon atom in a single step under mild reaction conditions. The process, devoid of stoichiometric additives, benefits from the use of bench‐stable and easy‐to‐handle reagents, is operationally simple, and tolerates a wide variety of functional groups.