Performance comparison of differential space-time signalling schemes for OFDM systems

Differential transmit diversity is an attractive alternative to its coherent counterpart, especially for multiple antenna systems where channel estimation is more difficult to attain compared to that of single antenna systems. In this paper we compare two different types of differential transmit diversity techniques for OFDM based transmissions. The first technique uses differential space-time block codes (DSTBC) from orthogonal designs and the second uses the differential cyclic delay diversity (DCDD). The results compare the bit error performance for several transmit antenna configurations. The results show that DCDD offers a very close performance to that of DSTBC, with the advantage of a simplified receiver structure

I. Catalysis of Intra- and Intermolecular Schmidt Reactions. II. Copper-Catalyzed Oxaziridine-Mediated C-H Bond Oxidation. III. Synthesis and Cytotoxic Evaluation of Withalongolide A Analogues.

The research presented herein describes four separate projects, focusing on synthetic methodology development, discovery of novel cytotoxic agents, and natural product isolation. Catalysis of Intra- and Intermolecular Schmidt Reactions A method for carrying out the intramolecular Schmidt reaction of alkyl azides and ketones using a substoichiometric amount of catalyst is described. Following extensive screening, the use of the strong hydrogen-bond-donating solvent hexafluoro-2-propanol (HFIP) was found to be consistent with low catalyst loadings, which ranged from 2.5 mol % for favorable substrates to 25 mol % for more difficult cases. Reaction optimization, broad substrate scope, and preliminary mechanistic studies of this improved version of the reaction are discussed. The use of HFIP as the solvent also allowed for the extension of this methodology to intermolecular variants of Schmidt reaction favoring the development of mild, operationally simple, and more efficient protocols, requiring considerably less amounts of acid catalysts for these variants. Copper-Catalyzed Oxaziridine-Mediated C-(&ndash)H Bond Oxidation. The highly regioand chemoselective oxidation of an activated C−(&ndash)H bond via a copper-catalyzed reaction of oxaziridine is described. The oxidation proceeded with a variety of substrates, primarily comprising of allylic and benzylic examples, as well as one example of an otherwise unactivated tertiary C−(&ndash)H bond. The mechanism of the reaction is proposed to involve single-electron transfer (SET) to the oxaziridines to generate a copper-bound radical anion, followed by hydrogen atom abstraction and collapse to products, with regeneration of the catalyst by a final SET event. The involvement of allylic radical intermediates en route to the product was supported by a radical-trapping experiment with TEMPO. Synthesis and Cytotoxic Evaluation of Withalongolide A Analogues. The natural product withaferin A exhibits potent antitumor activity and other diverse pharmacological activities. The recently discovered withalongolide A, a C-19 hydroxylated congener of withaferin A, was reported to possess cytotoxic activity against head and neck squamous cell carcinoma (HNSCC). Interestingly, semisynthetic acetylated analogues of withalongolide A were shown to be considerably more cytotoxic than the parent compound. To further explore the structure-(&ndash)activity relationship (SAR), 20 new semisynthetic analogues of this highly oxygenated withalongolide A were designed, synthesized, and evaluated for cytotoxic activity against four different cancer cell lines. A number of derivatives were found to be more potent than the parent compound and withaferin A. Isolation of Withalongolide O from Physalis longifolia. The SAR analysis of reported bioactive withanolides revealed certain crucial structural requisites for possessing a potent cytotoxic activity. The semisynthesis of a putative unnatural withanolide incorporating all the basic and essential structural features to boost the antiproliferative activity was contemplated. Withaferin A was considered as an appropriate starting material for this purpose. Although the semisynthetic efforts met with failure, it was during the isolation of withaferin A from the crude plant extract that we discovered a novel withanolide, withalongolide O. The structure of withalongolide O was determined using various spectroscopic techniques and subsequently confirmed by X-ray crystallographic analysis. Both withalongolide O and its diacetate exhibited potent cytotoxicity against four different cancer cell lines

Synthesis, spectroscopic study of Pt (IV), Au (III), Rh(III),Co(II) and V (IV) complexes with sodium[5-(p-nitro phenyl) -/4- phenyl-1,2,4-triazole-3-dithiocarbamato hydrazide] and cytotoxicity assay on rhabdomyosarcoma cell line of heavy metals

All the prepared metal complexes of Pt (IV), Au(III), Rh (III), Co (II) and V(IV) with new ligand sodium [5-(p-nitro phenyl)-/4-phenyl-1,2,4-triazole-3-dithiocarbamato hydrazide] (TRZ.DTC) have been synthesized and characterized in solid state by using flame atomic absorption, elemental analysis C.H.N.S, FT-IR ,UV-Vis Spectroscopy, conductivity and magnetic susceptibility measurements. The nature of the complexes formed in ethanolic solution has been studied following the molar ratio method also was studied stability constant and found to be stable in molar ratio1:1 of VL (IV) and CoL(II) while Pt(IV), Au(III) and Rh(III) complexes stable in molar ratio 1:2 as well as the molar absorptivity for these complexes were calculated. From the previous analyses, octahedral geometry was suggested for Pt (IV), Rh (III) and Co (II) complexes, square planar was suggested for Au(III) complex while V(IV) complex has a square pyramidal. Cytotoxic effect of PtL, AuL and RhL as well as ligand has been evaluated against RD cell line by using four different concentrations (500, 250, 125 & 62.5 µg/ml) respectively in three exposure times 24, 48 and 72 hrs and compared this effect with control positive Cis-Pt

Antioxidant and antityrosinase activities of piper maingayi HK. Essential oils

The study was aimed to investigate the chemical components of stem and fruit volatile oils of Piper. maingayi Hk. with their antioxidant and antityrosinase activities. GC and GC-MS analysis of the essential oils obtained from the fresh stem and fruit of P. maingayi Hk. resulted in the identification of 34 and 18 components accounting for 83.6% and 78.7% of the total amount, respectively. Sesquiterpene hydrocarbons and oxygenated sesquiterpenes were the most highly represented classes as the former ranging from 64.7% to 70.7%, and the latter varying from 7.4% to 8.6%. The main constituents of the stem oil were: α-caryophyllene (26.2%), α-cedrene (8.4%), caryophyllene oxide (6.7%) and cis-calamenene (6.2%), while the fruit oil was dominated by δ-cadinene (22.6%), β-caryophyllene (18.8%), α-copaene (11.2%) and α-cadinol (7.1%). The stem and fruit of P. maingayi oils showed significant value for antioxidant and antityrosinase activities

Improved Schmidt Conversion of Aldehydes to Nitriles Using Azidotrimethylsilane in 1,1,1,3,3,3-Hexafluoro-2-propanol

This work is licensed under a Creative Commons Attribution 4.0 International License.The Schmidt reaction of aromatic aldehydes using a substoichiometric amount (40 mol %) of triflic acid is described. Low catalyst loading was enabled by a strong hydrogen-bond-donating solvent hexafluoro-2-propanol (HFIP). This improved protocol tolerates a broad scope of aldehydes with diverse functional groups and the corresponding nitriles were obtained in good to high yields without the need for aqueous work up.University of Kansa

LptO (PG0027) is required for lipid A 1-phosphatase activity in Porphyromonas gingivalis W50

ABSTRACT Porphyromonas gingivalis produces outer membrane vesicles (OMVs) rich in virulence factors, including cysteine proteases and A-LPS, one of the two lipopolysaccharides (LPSs) produced by this organism. Previous studies had suggested that A-LPS and PG0027, an outer membrane (OM) protein, may be involved in OMV formation. Their roles in this process were examined by using W50 parent and the Δ PG0027 mutant strains. Inactivation of PG0027 caused a reduction in the yield of OMVs. Lipid A from cells and OMVs of P. gingivalis W50 and the Δ PG0027 mutant strains were analyzed by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Lipid A from W50 cells contained bis-P-pentaacyl, mono-P-pentaacyl, mono-P-tetraacyl, non-P-pentaacyl, and non-P-tetraacyl species, whereas lipid A from Δ PG0027 mutant cells contained only phosphorylated species; nonphosphorylated species were absent. MALDI-TOF/TOF tandem MS of mono-P-pentaacyl ( m / z 1,688) and mono-P-tetraacyl ( m / z 1,448) lipid A from Δ PG0027 showed that both contained lipid A 1-phosphate, suggesting that the Δ PG0027 mutant strain lacked lipid A 1-phosphatase activity. The total phosphatase activities in the W50 and the Δ PG0027 mutant strains were similar, whereas the phosphatase activity in the periplasm of the Δ PG0027 mutant was lower than that in W50, supporting a role for PG0027 in lipid A dephosphorylation. W50 OMVs were enriched in A-LPS, and its lipid A did not contain nonphosphorylated species, whereas lipid A from the Δ PG0027 mutant (OMVs and cells) contained similar species. Thus, OMVs in P. gingivalis are apparently formed in regions of the OM enriched in A-LPS devoid of nonphosphorylated lipid A. Conversely, dephosphorylation of lipid A through a PG0027-dependent process is required for optimal formation of OMVs. Hence, the relative proportions of nonphosphorylated and phosphorylated lipid A appear to be crucial for OMV formation in this organism. IMPORTANCE Gram-negative bacteria produce outer membrane vesicles (OMVs) by “blebbing” of the outer membrane (OM). OMVs can be used offensively as delivery systems for virulence factors and defensively to aid in the colonization of a host and in the survival of the bacterium in hostile environments. Earlier studies using the oral anaerobe Porphyromonas gingivalis as a model organism to study the mechanism of OMV formation suggested that the OM protein PG0027 and one of the two lipopolysaccharides (LPSs) synthesized by this organism, namely, A-LPS, played important roles in OMV formation. We suggest a novel mechanism of OMV formation in P. gingivalis involving dephosphorylation of lipid A of A-LPS controlled/regulated by PG0027, which causes destabilization of the OM, resulting in blebbing and generation of OMVs. </jats:p

Sistem pemantauan transformer dengan IoT

Artikel ini sebagai laporan untuk kajian yang berkaitan transformer dan sistem pemantauan masa nyata. Dalam dekad yang lalu, banyak perhatian dibuat untuk memperkenalkan sistem pintar dan peralatan untuk memenuhi keperluan semasa dan menjadikan kehidupan selesa. Satu kepentingan baru-baru ini dalam komunikasi Mesin ke Mesin dikenali sebagai Internet of Things (IOT), untuk membolehkan peranti autonomi menggunakan Internet untuk bertukar data. Kerja-kerja ini membentangkan reka bentuk dan pelaksanaan pemantauan masa nyata dan pengesanan kesalahan pengubah dan rekod penunjuk operasi utama pengubah penyebaran seperti beban semasa, voltan, minyak pengubah dan merangkumi suhu dan kelembapan. Transformer adalah salah satu peralatan elektrik yang paling penting yang digunakan dalam sistem penghantaran kuasa kerana mereka melaksanakan fungsi mengubah tahap voltan. Oleh itu, penyelenggaraan pengubah kuasa adalah wajib; kerana ia terletak di kawasan geografi yang berbeza, pemantauan berkala tidak mungkin sepanjang masa disebabkan oleh tenaga manusia yang tidak mencukupi. Sekiranya ada sesuatu yang tidak normal atau keadaan kecemasan berlaku, sistem itu boleh dipantau melalui internet yang mengandungi maklumat tentang ketidaknormalan mengikut beberapa arahan yang telah ditetapkan yang diprogramkan dalam mikrokontroler. Sistem ini akan membantu transformer untuk beroperasi dengan lancar dan mengenal pasti masalah sebelum sebarang kegagalan bencana

DYNAMIC THRESHOLDING GA-BASED ECG FEATURE SELECTION IN CARDIOVASCULAR DISEASE DIAGNOSIS

Electrocardiogram (ECG) data are usually used to diagnose cardiovascular disease (CVD) with the help of a revolutionary algorithm. Feature selection is a crucial step in the development of accurate and reliable diagnostic models for CVDs. This research introduces the dynamic threshold genetic algorithm (DTGA) algorithm, a type of genetic algorithm that is used for optimization problems and discusses its use in the context of feature selection. This research reveals the success of DTGA in selecting relevant ECG features that ultimately enhance accuracy and efficiency in the diagnosis of CVD. This work also proves the benefits of employing DTGA in clinical practice, including a reduction in the amount of time spent diagnosing patients and an increase in the precision with which individuals who are at risk of CVD can be identified

Cyclic Self-Organizing Map for Object Recognition

Object recognition is an important machine learning (ML) application. To have a robust ML application, we need three major steps: (1) preprocessing (i.e. preparing the data for the ML algorithms); (2) using appropriate segmentation and feature extraction algorithms to abstract the core features data and (3) applying feature classification or feature recognition algorithms. The quality of the ML algorithm depends on a good representation of the data. Data representation requires the extraction of features with an appropriate learning rate. Learning rate influences how the algorithm will learn about the data or how the data will be processed and treated. Generally, this parameter is found on a trial-and-error basis and scholars sometimes set it to be constant. This paper presents a new optimization technique for object recognition problems called Cyclic-SOM by accelerating the learning process of the self-organizing map (SOM) using a non-constant learning rate. SOM uses the Euclidean distance to measure the similarity between the inputs and the features maps. Our algorithm considers image correlation using mean absolute difference instead of traditional Euclidean distance. It uses cyclical learning rates to get high performance with a better recognition rate. Cyclic-SOM possesses the following merits: (1) it accelerates the learning process and eliminates the need to experimentally find the best values and schedule for the learning rates; (2) it offers one form of improvement in both results and training; (3) it requires no manual tuning of the learning rate and appears robust to noisy gradient information, different model architecture choices, various data modalities and selection of hyper-parameters and (4) it shows promising results compared to other methods on different datasets. Three wide benchmark databases illustrate the efficiency of the proposed technique: AHD Base for Arabic digits, MNIST for English digits, and CMU-PIE for faces