Synthesis of Macrocycles Derived from Substituted Triazines

A triazine ring derivatized with morpholine, an N-alkyl-N′-BOC-hydrazine (alkyl=isopropyl or benzyl) and the diethylacetal of glycinylpropionaldehyde undergoes spontaneous dimerization in good yields upon acid-catalyzed deprotection. The resulting 24-member macrocycles can be characterized by NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction. In the solid state, both homodimers adopt a taco-like conformation. Although each shows π–π stacking between the triazine rings, different patterns of hydrogen bonds emerge. The crystal structure of the isopropyl dimer shows that it includes two molecules of trifluoracetic acid per macrocycle. The trifluoroacetate anion charge balances the protonated triazines, which engage in bifurcated hydrogen bonds with the carbonyl acceptor of the distant glycine. This carbonyl also forms a hydrogen bond with the NH of the proximate glycine. The crystal structure of the benzyl derivative does not include trifluoracetic acid. Instead, two hydrogen bonds form, each between a glycine NH and the lone pair of the C=N nitrogen of the hydrazine group. In the solid state, both molecules present the alkyl side chains and morpholine groups in close proximity. A heterodimer is accessible in approximately statistical yields—along with both homodimers—by mixing the two protected monomers prior to subjecting them to deprotection.     

Fabrication and in vitro characterization of fenofibric acid-loaded hyaluronic acid–polyethylene glycol polymeric composites with enhanced drug solubility and dissolution rate

The target of the present work was to formulate and characterize a fenofibric acid-loaded hyaluronic acid–polyethylene glycol (HA-PEG) polymeric composite to improve solubility and dissolution of the drug in the aqueous media. Several fenofibric acid-loaded HA-PEG polymeric composites were fabricated with varying quantities of HA and PEG 6000 using the solvent-evaporation method. The impact of relative quantities of HA and PEG was examined on solubility and dissolution of the drug. The thermal and structural physiognomies were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Spectroscopic study was accomplished by Fourier transform infrared spectroscopy (FTIR). Shape and surface features of the solid particles were observed using scanning electron microscopy (SEM). All the formulations demonstrated greater solubility and dissolution than did plain fenofibric acid powder. Both the HA and PEG positively affected solubility and dissolution of the drug in the aqueous media. A fenofibric acid-loaded HA-PEG polymeric composite, consisting of fenofibric acid/HA/PEG at the weight ratio of 0.5/6.0/0.75, respectively, provided the highest solubility (0.45?±?0.05?mg/mL) and dissolution (～90% in 15?min) in this study. Moreover, the loaded drug was in the amorphous state, and had no covalent linkages with polymeric matrices. Thus, this HA-PEG polymeric composite might be a suitable drug delivery system for oral administration of fenofibric acid.     

Coordination Polymer to Atomically Thin,Holey, Metal‐Oxide Nanosheets for Tuning Band Alignment

Holey 2D metal oxides have shown great promise as functional materials for energy storage and catalysts. Despite impressive performance, their processing is challenged by the requirement of templates plus capping agents or high temperatures; these materials also exhibit excessive thicknesses and low yields. The present work reports a metal‐based coordination polymer (MCP) strategy to synthesize polycrystalline, holey, metal oxide (MO) nanosheets with thicknesses as low as two‐unit cells. The process involves rapid exfoliation of bulk‐layered, MCPs (Ce‐, Ti‐, Zr‐based) into atomically thin MCPs at room temperature, followed by transformation into holey 2D MOs upon the removal of organic linkers in aqueous solution. Further, this work represents an extra step for decorating the holey nanosheets using precursors of transition metals to engineer their band alignments, establishing a route to optimize their photocatalysis. The work introduces a simple, high‐yield, room‐temperature, and template‐free approach to synthesize ultrathin holey nanosheets with high‐level functionalities.     

Hybrid GrabCut Hidden Markov Model for Segmentation

Diagnosing data or object detection in medical images is one of the important parts of image segmentation especially those data which is less effective to identify in MRI such as low-grade tumors or cerebral spinal fluid (CSF) leaks in the brain. The aim of the study is to address the problems associated with detecting the low-grade tumor and CSF in brain is difficult in magnetic resonance imaging (MRI) images and another problem also relates to efficiency and less execution time for segmentation of medical images. For tumor and CSF segmentation using trained light field database (LFD) datasets of MRI images. This research proposed the new framework of the hybrid k-Nearest Neighbors (k-NN) model that is a combination of hybridization of Graph Cut and Support Vector Machine (GCSVM) and Hidden Markov Model of k-Mean Clustering Algorithm (HMMkC). There are four different methods are used in this research namely (1) SVM, (2) GrabCut segmentation, (3) HMM, and (4) k-mean clustering algorithm. In this framework, on the one hand, phase one is to perform the classification of SVM and Graph Cut algorithm to create the maximum margin distance. This research use GrabCut segmentation method which is the application of the graph cut algorithm and extract the data with the help of scale-invariant features transform. On the other hand, in phase two, segment the low-grade tumors and CSF using a method adapted for HMkC and extract the information of tumor or CSF fluid by GCHMkC including iterative conditional maximizing mode (ICMM) with identifying the range of distant. Comparative evaluation is also performing by the comparison of existing techniques in this research. In conclusion, our proposed model gives better results than existing. This proposed model helps to common man and doctor that can identify their condition of brain easily. In future, this will model will use for other brain related diseases.     

Hot corrosion behavior of double ceramic layered CaZrO3/Yttria‐stabilized zirconia coatings

A novel double ceramic layered (DCL) CaZrO₃/Yttria‐stabilized zirconia (YSZ) thermal barrier coatings (TBCs) was designed for improved service life against sulfate vanadate hot corrosion as compared with that of YSZ single layered coating. The hot corrosion behavior of DCL CaZrO₃/YSZ coatings was studied at 950°C after dry spreading 50%Na₂SO₄+50%V₂O₅ mixture onto a coated surface. The CaZrO₃ as the topmost layer in DCL CaZrO₃/YSZ coatings, served as a sacrificial layer during sulfate vanadate hot corrosion protecting the underneath YSZ coating. The corrosion reactions in this case were sluggish due to the initial formation of low melting point meta‐calcium vanadate (CaV₂O₆) that isothermally transformed to higher melting point calcium vanadates having higher calcia (CaO) content. The corrosion reaction products sealed the top surface, impeding the oxygen movement and eventually retarded the thermally grown oxide (TGO) growth. The sulfate vanadate hot corrosion life of the DCL CaZrO₃/YSZ coatings was observed to be more than double as compared with single ceramic layered YSZ coatings.     

Study of oxygen plasma pre-treatment of polyester fabric for improved polypyrrole adhesion

In this work, we have systematically studied the improvement of binding of polypyrrole with polyethylene terephthalate (PET) thin films and fabrics using low pressure oxygen plasma. A range of plasma treatment times were employed to investigate plasma induced effects on surface roughness, surface chemistry and hydrophilicity. Modifications of PET films were studied with respect to surface morphology by means of atomic force and scanning electron microscopy. Chemical effects of plasma treatment were studied using X-ray photoelectron spectroscopy. Results showed that both the increase in surface functionalisation by carboxylic groups and formation of nano size roughness contributed to improved adhesion and conductivity.     

On the Use of Fractional-Order Controllers for Performance Improvements in AC Drives

Abstract—The control performance of AC electric drives is sensitive to and often degrades with parametric variations. This article proposes the use of fractional-order controllers to combat parameter variations. The speed control of an AC induction motor drive achieved through indirect field-oriented control is considered for illustration. The performance of the proposed controller is compared with a well-tuned proportional-integral controller when critical motor parameters are subject to parametric variations about their nominal values. Dynamic simulations in MATLAB/Simulink (The Math Works, Natick, Massachusetts, USA) are conducted to assess control performance.     

Perspectives of low cost arsenic remediation of drinking water in Pakistan and other countries

Arsenic concentrations above acceptable standards for drinking water have been detected in many countries and this should therefore is a global issue. The presence of arsenic in subsurface aquifers and drinking water systems is a potentially serious human health hazard. The current population growth in Pakistan and other developing countries will have direct bearing on the water sector for meeting the domestic, industrial and agricultural needs. Pakistan is about to exhaust its available water resources and is on the verge of becoming a water deficit country. Water pollution is a serious menace in Pakistan, as almost 70% of its surface waters as well as its groundwater reserves have contaminated by biological, organic and inorganic pollutants. In some areas of Pakistan, a number of shallow aquifers and tube wells are contaminated with arsenic at levels which are above the recommended USEPA arsenic level of 10 ppb (10 μg L⁻¹). Adverse health effects including human mortality from drinking water are well documented and can be attributed to arsenic contamination. The present paper reviews appropriate and low cost methods for the elimination of arsenic from drinking waters. It is recommended that a combination of low cost chemical treatment like ion exchange, filtration and adsorption along with bioremediation may be useful option for arsenic removal from drinking water.