bluuebunny/crossref_metadata_2025 huggingface dataset:
Diaryl‐Substituted Azolylthioacetamides: Inhibitor Discovery of New Delhi Metallo‐β‐Lactamase‐1 (NDM‐1)
Authors: Zhang Yi‐Lin , Yang Ke‐Wu , Zhou Ya‐Jun , LaCuran Alecander E. , Oelschlaeger Peter , Crowder Michael W.
Published: July 2014

The emergence and spread of antibiotic‐resistant pathogens is a global public health problem. Metallo‐β‐lactamases (MβLs) such as New Delhi MβL‐1 (NDM‐1) are principle contributors to the emergence of resistance because of their ability to hydrolyze almost all known β‐lactam antibiotics including penicillins, cephalosporins, and carbapenems. A clinical inhibitor of MBLs has not yet been found. In this study we developed eighteen new diaryl‐substituted azolylthioacetamides and found all of them to be inhibitors of the MβL L1 from Stenotrophomonas maltophilia (Ki<2 μM), thirteen to be mixed inhibitors of NDM‐1 (Ki<7 μM), and four to be broad‐spectrum inhibitors of all four tested MβLs CcrA from Bacteroides fragilis, NDM‐1 and ImiS from Aeromonas veronii, and L1 (Ki<52 μM), which are representative of the B1a, B1b, B2, and B3 subclasses, respectively. Docking studies revealed that the azolylthioacetamides, which have the broadest inhibitory activity, coordinate to the ZnII ion(s) preferentially via the triazole moiety, while other moieties interact mostly with the conserved active site residues Lys224 (CcrA, NDM‐1, and ImiS) or Ser221 (L1).
A New Class of Phase‐Selective Synthetic β‐Amino Acid Based Peptide Gelator: From Mechanistic Aspects to Oil Spill Recovery
Authors: Konda Maruthi , Maity Indrajit , Rasale Dnyaneshwar B. , Das Apurba K.
Published: July 2014

The mechanistic aspects of supramolecular ordering of synthetic β‐amino acid based peptides in different organic solvents and fuel oils are reported. The peptide Boc‐cis‐ACHC‐Aib‐Phe‐OMe (Boc=tert‐butyloxycarbonyl, cis‐ACHC=cis‐2‐aminocyclohexanecarboxylic acid, Aib=α‐amino isobutyric acid, Phe=phenylalanine; 1) is able to entrap various organic solvents and oils, leading to the formation of self‐supporting gels. Spectroscopic studies confirm the turn‐type β‐sheet arrangement of peptide 1 in the gel phase. A morphology study shows that a bundle of nanofibers form from self‐assembled peptide 1. Peptide 1 is capable of entrapping organic or oil layers selectively over the aqueous layer. Furthermore, the phase‐selective gelation behavior of peptide 1 is effectively used as a model study for oil spill recovery from a biphasic mixture of oil and water.
Dithienopyrrole‐/Benzodithiophene‐Based Donor–Acceptor Polymers for Memristor
Authors: Wang Cheng , Liu Gang , Chen Yu , Liu Shanshan , Chen Qibin , Li Runwei , Zhang Bin
Published: July 2014

Invited for this month’s cover is the group of Prof. Dr. Yu Chen from East China University of Science and Technology, P. R. China. The cover picture shows fundamental passive circuit elements of resistor, capacitor, inductor and memristor and the correlations between the circuit variables. Read the full text of the article at 10.1002/cplu.201402133
Selective growth of InAs quantum dots on GaAs driven by as kinetics
Authors: Magri R. , Placidi E. , Arciprete F. , Patella F.
Published: July 2014

In this paper we examine experimentally and theoretically how the As flux direction and intensity influences the recently observed selective growth of InAs quantum dots on the rippled surface of GaAs, where the dots line up only against well determined slopes of the mounded GaAs surface facing the impinging Arsenic flux. We have previously shown that the observed phenomenon is exclusively related to the As constituent, challenging the widespread belief that As plays only a minor role in the dot formation. The selective growth is obtained by Molecular Beam Epitaxy at high growth temperature and under a high As/In flux ratio. To interpret the experimental results, we use a newly developed kinetic model incorporating new features: (i) anions are explicitly considered; (ii) cations and anions follow a different kinetics; (iii) the dot surface is distinguished by the dot bulk and atoms are transferred back and forth between the two phases depending on the surface interaction with the environment. We find that even a very small difference in the As flux intensity impinging over two substrate regions produces a cation current flow from one region to the other, so that the dots form only on the region exposed to the largest flux.
Surface Decoration of ϵ‐Fe2O3 Nanorods by CuO Via a Two‐Step CVD/Sputtering Approach**
Authors: Barreca Davide , Carraro Giorgio , Peeters Daniel , Gasparotto Alberto , Maccato Chiara , Kessels Wilhelmus M. M. , Longo Valentino , Rossi Francesca , Bontempi Elza , Sada Cinzia , Devi Anjana
Published: July 2014

In this paper we report on the first example of Fe2O3/CuO composites fabricated by a two‐step vapor‐phase synthetic strategy. The target route is based on the CVD of Fe2O3 nanorod arrays on Si(100) at 400 °C starting from Fe(hfa)2TMEDA (hfa = 1,1,1,5,5,5‐hexafluoro‐2,4‐pentanedionate; TMEDA = N,N,N′,N′‐tetramethylethylenediamine), followed by radio frequency (RF) copper sputtering for various process durations, and final ex‐situ annealing in air. The combined use of complementary structural, morphological, and chemical analyses give evidence of the formation of pure nanocomposite systems, characterized by the presence of the sole ϵ‐Fe2O3 and CuO phases. The unique features of the adopted approach enable an efficient surface decoration of ϵ‐Fe2O3 rods by CuO nanoparticles a few nm in diameter, resulting in an intimate contact between the two oxides, and a CuO content tunable through variations of the sole sputtering time.
Efficient purification of CD4+ lymphocytes from peripheral blood progenitor cell products using affinity bead acoustophoresis
Authors: Lenshof Andreas , Jamal Arshad , Dykes Josefina , Urbansky Anke , Åstrand‐Grundström Ingbritt , Laurell Thomas , Scheding Stefan
Published: July 2014

Processing of peripheral blood progenitor cells (PBPC) for clinical transplantation or research applications aims to effectively isolate or deplete specific cell populations, utilizing primarily magnetic or fluorescence activated sorting methods. Here, we investigated the performance of microfluidic acoustophoresis for the separation of lymphocyte subsets from PBPC, and present a novel method for affinity‐bead‐mediated acoustic separation of cells which can otherwise not be acoustically discriminated. As the acoustic force on a particle depends on particle size, density and compressibility, targeting of cells by affinity specific beads will generate cell‐bead complexes that exhibit distinct acoustic properties relative to nontargeted cells and are, thus, possible to isolate. To demonstrate this, PBPC samples (n = 22) were obtained from patients and healthy donors. Following density gradient centrifugation, cells were labeled with anti‐CD4‐coated magnetic beads (Dynal) and isolated by acoustophoresis and, for comparison, standard magnetic cell sorting technique in parallel. Targeted CD4+ lymphocytes were acoustically isolated with a mean (±SD) purity of 87 ± 12%, compared with 96 ± 3% for control magnetic sorting. Viability of sorted cells was 95 ± 4% (acoustic) and 97 ± 3% (magnetic), respectively. The mean acoustic separation efficiency of CD4+ lymphocytes to the target fraction was 65 ± 22%, compared with a mean CD4+ lymphocyte recovery of 56 ± 15% for magnetic sorting. Functional testing of targeted CD4+ lymphocytes demonstrated unimpaired mitogen‐mediated proliferation capacity and cytokine production. Hematopoietic progenitor cell assays revealed a preserved colony forming ability of nontarget cells post sorting. We conclude that the acoustophoresis platform can be utilized to efficiently isolate bead‐labeled CD4+ lymphocytes from PBPC samples in a continuous flow format, with preserved functional capacity of both target and nontarget cells. These results open up for simultaneous affinity‐bead‐mediated separation of multiple cell populations, something which is not possible with current standard magnetic cell separation technology. © 2014 International Society for Advancement of Cytometry
Large‐scale adaptive divergence in Boechera fecunda, an endangered wild relative of Arabidopsis
Authors: Leamy Larry J. , Lee Cheng‐Ruei , Cousins Vanessa , Mujacic Ibro , Manzaneda Antonio J. , Prasad Kasavajhala , Mitchell‐Olds Thomas , Song Bao‐Hua
Published: July 2014

Many biological species are threatened with extinction because of a number of factors such as climate change and habitat loss, and their preservation depends on an accurate understanding of the extent of their genetic variability within and among populations. In this study, we assessed the genetic divergence of five quantitative traits in 10 populations of an endangered cruciferous species, Boechera fecunda, found in only several populations in each of two geographic regions (WEST and EAST) in southwestern Montana. We analyzed variation in quantitative traits, neutral molecular markers, and environmental factors and provided evidence that despite the restricted geographical distribution of this species, it exhibits a high level of genetic variation and regional adaptation. Conservation efforts therefore should be directed to the preservation of populations in each of these two regions without attempting transplantation between regions. Heritabilities and genetic coefficients of variation estimated from nested ANOVAs were generally high for leaf and rosette traits, although lower (and not significantly different from 0) for water‐use efficiency. Measures of quantitative genetic differentiation, QST, were calculated for each trait from each pair of populations. For three of the five traits, these values were significantly higher between regions compared with those within regions (after adjustment for neutral genetic variation, FST). This suggested that natural selection has played an important role in producing regional divergence in this species. Our analysis also revealed that the B. fecunda populations appear to be locally adapted due, at least in part, to differences in environmental conditions in the EAST and WEST regions.
Synthesis and Molecular Structures of Monosubstituted Pentamethylcobaltocenium Cations
Authors: Wolter‐Steingrube Anne , Bugenhagen Bernhard E. C. , Herrmann Carmen , Heck Jürgen
Published: July 2014

(Amino‐η5‐cyclopentadienyl)(pentamethyl‐η5‐cyclopentadienyl)cobalt(III) hexafluorophosphate (6PF6) was prepared by a route that started with the synthesis of the zwitterion (oxycarbonyl‐η5‐cyclopentadienyl)(pentamethyl‐η5‐cyclopentadienyl)cobalt(III) (1). The acidification of 1 created the carboxylic acid 2PF6, which was converted into the acyl chloride 3PF6. The reaction with NaN3 afforded the azide 4PF6, which was transformed to the carbamate 5PF6. The hydrolysis of 5PF6 afforded the desired aminocobaltocenium compound 6PF6. The oxidation of 6PF6 yielded the (nitro‐η5‐cyclopentadienyl)(pentamethyl‐η5‐cyclopentadienyl)cobalt(III) cation 7+. For 1, 2+, 4PF6, 6PF6, and 7PF6, X‐ray structure analyses were performed. The electronic structure of 6+ calculated by DFT methods revealed a short C–N bond, which is in agreement with the molecular structure obtained from X‐ray structure analysis. The pKa value of 6PF6 was estimated from aqueous solution. Cyclic voltammetry studies show a reversible one‐electron reduction and an irreversible one‐electron oxidation.
A Concise Synthesis of (2R,3R)‐ and (2R,3S)‐3‐Hydroxypipecolic Acids, and Total Synthesis of (–)‐Deoxoprosopinine and (+)‐2‐epi‐Deoxoprosopinine from D‐Glycals
Authors: Mallick Asadulla , Kumari Nitee , Roy Rashmi , Palanivel Ashokkumar , Vankar Yashwant D.
Published: July 2014

Short and efficient formal syntheses of (2R,3R)‐ and (2R,3S)‐3‐hydroxypipecolic acids, and total syntheses of (–)‐deoxoprosopinine and (+)‐2‐epi‐deoxoprosopinine have been achieved starting from D‐glycals. The key steps involved in these syntheses were Ferrier rearrangement, azide reduction, intramolecular cyclization, and Grignard reaction.
Application and Scope of Schreiber's Gold(I)‐Catalyzed α‐Pyrone Synthesis to Ring A Aromatic Podolactones
Authors: Sánchez‐Larios Eduardo , Giacometti Robert D. , Hanessian Stephen
Published: July 2014

Schreiber's gold(I)‐catalyzed synthesis of α‐pyrones was adapted to the total synthesis of a ring A aromatic podolactone, urbalactone. The scope of the acetylenic ester partner in the formation of α‐pyrones was studied. The total synthesis features, as key steps, α‐pyrone formation, Friedel–Crafts cyclization, Stille coupling, and a N,N′‐dicyclohexylcarbodiimide/4‐(N,N‐dimethylamino)pyridine lactonization to generate the γ‐lactone. Several α‐pyrone intermediates from this work exhibited in vitro antiproliferative activity against the A2780 ovarian cancer cell line.
Is It an Eating Disorder or Achalasia or Both? A Literature Review and Diagnostic Challenges
Authors: Reas Deborah L. , Zipfel Stephan , Rø Øyvind
Published: July 2014

Introduction

Achalasia is a rare oesophageal motility disorder characterized by physical, behavioural and psychosocial features that are strikingly similar to eating disorders (ED).

Method

A literature search of PubMed and Google Scholar identified 36 cases of achalasia from 11 countries misdiagnosed as ED between 1980 and 2013.

Results

On average, the typical misdiagnosed case was an 18‐year‐old female with an average weight loss of 16.2 kg. Vomiting behaviour in achalasia was distinguished by occurring after both solids and liquids, occurring in public, and worsening at night or while lying down, and was associated with pain relief. Manometric investigations of oesophageal functioning in clinical ED samples are few and have shown little evidence of dysmotility.

Discussion

Achalasia and ED share numerous clinical features including weight loss and vomiting. Pain associated with swallowing difficulties may lead to an increasingly restricted pattern of eating and food avoidance. Increased awareness of achalasia in ED treatment settings can help facilitate detection of achalasia, thereby reducing treatment delay. © 2014 The Authors. European Eating Disorders Review published by John Wiley & Sons, Ltd.
Natural Gas & Electricity Pricing: Why Virtual Pipelines Transporting CNG Are Becoming a Reality
Authors: Bodell Tanya
Published: July 2014

What happens when supply of a major input to production shifts dramatically? Markets find a way.
Medicare Part B Intensity and Volume Offset
Authors: Brunt Christopher S.
Published: July 2014

Under Medicare Part B, adjustments to the fee schedule are made under the assumption that physicians and hospitals make up for fee reductions through increased service provision called ‘volume offsetting’. While historically, researchers have found evidence of volume offsetting, more recent studies have called into question its magnitude and existence. This study is the first to propose and empirically evaluate an alternative hypothesis of offsetting, namely the alteration of billed or provided services as a means of ‘intensity offsetting’. Evaluating both forms of offsetting, it finds strong evidence of intensity offsetting and little to no evidence of volume offsetting. Simulating a 10% reduction in the Medicare fee schedule, this study estimates that across different procedures between 22% and 59% of a fee reduction will be offset through alterations in service intensity. Copyright © 2014 John Wiley & Sons, Ltd.
The electrochemical production of boric acid
Authors: Yakar Elbeyli İffet , Turan Abdullah Zahid , Kalafatoğlu İ. Ersan
Published: July 2014

BACKGROUND

Boric acid (H3BO3) was electrochemically produced from borax pentahydrate (Na2B4O7.5H2O) using membrane electrolysis, and a flow diagram of the production process was developed. The effect of different catholyte concentrations (10, 20 and 30% aqueous NaOH) and current densities (1.2, 1.8 and 2.9 kA m−2) on current efficiency was studied. The electrical power consumption per ton of boric acid produced was calculated and the qualities of boric acid products were determined.

RESULTS

The current efficiency ranged between 94% and 74% depending on operating conditions. Optimum process conditions for electrochemical boric acid production were determined to be 1.8 kA m−2 current density and 20% aqueous NaOH catholyte concentration. In these conditions, the specific energy consumption for 1 ton of boric acid produced was calculated at 2000 kWh (i.e. specific energy consumption 2000 kWh ton−1 at 7.5 V and 1.8 kA m−2).

CONCLUSIONS

The production of boric acid by an electrochemical method is more attractive than the current commercial process and other production methods described in the literature. The process is environment friendly since it does not generate solid waste, and oxygen is produced instead of chlorine as in the well‐known chlor‐alkali process. © 2014 Society of Chemical Industry
Chemical profile and antiacetylcholinesterase, antityrosinase, antioxidant and α‐glucosidase inhibitory activity of Cynometra cauliflora L. leaves
Authors: Ado Muhammad Abubakar , Abas Faridah , Ismail Intan Safinar , Ghazali Hasanah M , Shaari Khozirah
Published: July 2014

BACKGROUND

The aim of the current study was (i) to evaluate the bioactive potential of the leaf methanolic extract of Cynometra cauliflora L., along with its respective hexane, dichloromethane, ethyl acetate (EtOAc), n‐butanol (n‐BuOH) and aqueous fractions, in inhibiting the enzymes α‐glucosidase, acetylcholinesterase (AChE) and tyrosinase as well as evaluating their antioxidant activities. (ii) In addition, in view of the limited published information regarding the metabolite profile of C. cauliflora, we further characterized the profiles of the EtOAc and n‐BuOH fractions using liquid chromatography–diode array detection–electrospray ionization–tandem mass spectrometry.

RESULTS

The leaf methanolic extract of C. cauliflora exhibited potent inhibition of all three enzymes and high antioxidant activity. The bioactivity was found to be concentrated in the EtOAc and n‐BuOH fractions. A total of 18 compounds were identified in these bioactive fractions, comprising a procyanidin trimer, procyanidin tetramer, procyanidin hexamer, taxifolin pentoside, catechin, vitexin, isovitexin, kaempferol hexoside, quercetin pentoside, quercetin hexoside, apigenin‐6‐C‐glucoside‐8‐C‐glucoside, kaempferol–coumaroyl hexoside and isorhamnetin hexoside.

CONCLUSION

The results indicated that C. cauliflora, the leaves in particular, is a rich source of bioactive compounds and could be beneficial for further development of high‐value phytomedicinal preparations and functional food products. © 2014 Society of Chemical Industry
Dispersive liquid–liquid microextraction combined with non‐aqueous capillary electrophoresis for the determination of imazalil, prochloraz and thiabendazole in apples, cherry tomatoes and grape juice
Authors: Xu Lina , Luan Feng , Liu Huitao , Gao Yuan
Published: July 2014

BACKGROUND

Fruit and vegetables are frequently treated with fungicides to reduce possible spoilage. As a result, fungicide residues may be accumulated in derived products. This important group of chemical compounds has been heavily regulated because of their potential toxicity. Therefore, a simple and rapid method to determine fungicides is desired.

RESULTS

A simple non‐aqueous capillary electrophoresis (NACE) method based on dispersive liquid–liquid microextraction (DLLME) has been proposed for the determination of imazalil, prochloraz and thiabendazole fungicides in fruits and juice samples. Separation buffer consisted of a methanol–acetonitrile mixture (35:65, v/v) containing 30 mmol L−1 ammonium chloride and 0.5% phosphoric acid. The optimum DLLME conditions were 80 µL trichloromethane as extraction solvent, 0.5 mL tetrahydrofuran as disperser solvent, sample solution pH at 6.0, 5% (w/v) NaCl and 10 s extraction time. Recoveries obtained for various samples ranged from 72% to 102%, with relative standard deviation lower than 6.4%. The limits of detection ranged from 0.47 to 0.72 µg kg−1.

CONCLUSION

The proposed method takes the advantages of DLLME and NACE. It is rapid, accurate, sensitive and reproducible for the determination of imazalil, prochloraz and thiabendazole in fruit samples. © 2014 Society of Chemical Industry
Correlation of striatal dopamine transporter imaging with post mortem substantia nigra cell counts
Authors: Kraemmer Julia , Kovacs Gabor G. , Perju‐Dumbrava Laura , Pirker Susanne , Traub‐Weidinger Tatiana , Pirker Walter
Published: July 2014

Dopamine transporter imaging is widely used for the differential diagnosis of parkinsonism. Only limited data are available on the relationship between striatal dopamine transporter binding and dopaminergic cell loss in the substantia nigra (SN). We analyzed postmortem SN cell counts in patients who had previously undergone dopamine transporter single‐photon emission computed tomography (SPECT). Pathological diagnoses included Parkinson's disease (n = 1), dementia with Lewy bodies (n = 2), multiple system atrophy (n = 1), corticobasal degeneration (n = 2), atypical parkinsonism with multiple pathological conditions (n = 1), Alzheimer's disease (n = 1), and Creutzfeldt‐Jakob disease (n = 1). [123I]β‐CIT SPECT had been performed in all subjects using a standardized protocol on the same triple‐head gamma camera. The density of neuromelanin‐containing and tyrosine hydroxylase–positive substantia nigra neurons/mm2 was evaluated in paraffin‐embedded tissue sections by morphometric methods. Mean disease duration at the time of dopamine transporter imaging was 2.3 years, and the mean interval from imaging to death was 29.3 months (range, 4‐68 months). Visual analysis of dopamine transporter images showed reduced striatal uptake in all seven patients with neurodegenerative parkinsonism, but not in Alzheimer's and Creutzfeldt‐Jakob disease cases. Averaged [(right+left)/2] striatal uptake was highly correlated with averaged SN cell counts (rs = 0.98, P < 0.0005 for neuromelanin‐ and rs = 0.96, P < 0.0005 for tyrosine hydroxylase–positive cells). Similar strong correlations were found in separate analyses for the right and left sides. Striatal dopamine transporter binding highly correlated with postmortem SN cell counts, confirming the validity of dopamine transporter imaging as an excellent in vivo marker of nigrostriatal dopaminergic degeneration. © 2014 International Parkinson and Movement Disorder Society
Delphinidin‐3‐glucoside protects human umbilical vein endothelial cells against oxidized low‐density lipoprotein‐induced injury by autophagy upregulation via the AMPK/SIRT1 signaling pathway
Authors: Jin Xin , Chen Mingliang , Yi Long , Chang Hui , Zhang Ting , Wang Li , Ma Wanqiang , Peng Xiaoli , Zhou Yong , Mi Mantian
Published: July 2014

Scope

Oxidized LDL (oxLDL) induced vascular endothelial cell injury is a key event in the pathogenesis of atherosclerosis (AS). In our previous studies, we showed that delphinidin‐3‐glucoside (Dp), a natural anthocyanin, attenuated oxLDL‐induced injury in human umbilical vein endothelial cells (HUVECs), indicating its potential role in preventing AS. However, the involved mechanism is not fully understood.

Methods and results

Via methyl thiazolyl tetrazolium and flow cytometry assay, we found that Dp‐attenuated oxLDL‐induced cell viability decrease and apoptosis in HUVECs. Depending on confocal microscopy, transmission electron microscopy, and Western blot assay, we found that Dp‐induced autophagy in HUVECs, whereas suppression of autophagy significantly abolished the protective role of Dp against oxLDL‐induced endothelial cell injury. Furthermore, Dp upregulated sirtuin 1 (SIRT1) expression and SIRT1 knockdown notably suppressed Dp‐induced autophagy in HUVECs. Dp also increased the expression of phosphorylated adenosine monophosphate‐activated protein kinase, while adenosine monophosphate‐activated protein kinase (AMPK) knockdown remarkably abolished Dp‐induced SIRT1 expression and subsequent autophagy.

Conclusion

Our data suggested that Dp protected HUVECs against oxLDL‐induced injury by inducing autophagy via the adenosine monophosphate‐activated protein kinase/SIRT1 signaling pathway. This new finding might shed light to the prevention and therapy of AS.
Extraction and measurement sensitivity improvement of third‐order autocorrelation trace from mixed autocorrelations
Authors: Wei Yizhen , Gao Shiming
Published: July 2014

A valuable insight is presented on obtaining high‐sensitivity third‐order autocorrelation trace in the wavelength and power regimes where both two‐ and three‐photon absorption of the detector should be considered. Theoretical analysis and experimental results are provided to discuss the limitations to the measurement sensitivity. By developing a new algorithm of harmonics detection, an approach is also proposed to improve the measurement sensitivity beyond our previous demonstration. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2234–2237, 2014
Ultra wide band vertex truncated printed pentagon monopole antenna
Authors: Ray Kamla Prasan , Thakur S. S.
Published: July 2014

Printed vertex truncated pentagon monopole antenna has been proposed, which yields ultra wide bandwidth. It gives bandwidth (BW) for VSWR ≤ 2 of 1.5–12 GHz. This new configuration has approximate omnidirectional radiation patterns in the azimuth plane throughout the BW. Simulated as well as measured results are presented, which are in agreement. The design equation for calculating the lower band edge frequency has also been derived for the printed pentagon monopole antenna. Systematic explanation has been given using impedance and surface current variations for ultra wide response. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2228–2234, 2014
Comparing phase noise of integer‐N phase‐locked loop of voltage‐controlled and digitally controlled oscillators
Authors: Wu Jian‐Ming , Chou Stephen , Li Simon Cimin , Ho Cheng‐Yu
Published: July 2014

This article compares the phase noise of an integer‐N phase‐locked loop (PLL) obtained using a voltage‐controlled oscillator (VCO) with those obtained using a digitally controlled oscillator (DCO). The cores of both VCO and DCO are single‐ended Clapp oscillators. To select the frequency of oscillation, a conventional analogue control is used in the VCO while a five‐bit digitally controlled circuit is adopted in the DCO. The VCO and DCO are designed and implemented using Agilent's GaAs HEMT ATF55143. Both are used in a PE3335 integer‐N PLL from Peregrine Semiconductor, and the performance of each is investigated in terms of phase noise. Careful comparison reveals that the integer‐N PLL with the DCO has a 7 dBc/Hz lower phase noise inside the loop bandwidth than the integer‐N PLL with the VCO. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2226–2228, 2014
Design and implementation of squared and octagonal W‐band CMOS marchand baluns for W‐band communication systems
Authors: Lin Yo‐Sheng , Liu Feng‐Chen , Wen Wei‐Chen
Published: July 2014

An enhanced squared and an enhanced octagonal W‐band CMOS Marchand baluns for direct‐conversion transceiver are reported. These Marchand baluns can be applied to an up‐conversion mixer for converting the single local oscillator input signal into differential signal, and converting the differential RF output signal to single signal. They can also be applied to a subharmonic down‐conversion mixer for converting the single RF input signal into differential signal. Instead of the traditional Marchand balun structure that uses three sections of thin (0.53 μm) M5 interconnection lines (underneath the thick (2.34 μm) M6 main structure), the proposed balun structures use only one section of thin M5 interconnection line to improve S21 and S31. The squared Marchand balun occupies a small chip area of 0.0313 mm2, and achieves S21 of −4.19 to −4.53 dB, S31 of −4.28 ∼ to −4.42 dB, magnitude of amplitude imbalance (MAI) smaller than 0.11 dB and deviation of phase difference (DPD) smaller than 4.3° for frequencies 75 ∼ −85 GHz. The octagonal Marchand balun occupies a small chip area of 0.0288 mm2, and achieves S21 of −4.56 to −5.03 dB, S31 of −4.56 to −4.86 dB, MAI smaller than 0.18 dB and DPD smaller than 2° for frequencies 75–85 GHz. The state‐of‐the‐art results of these proposed baluns indicate that they are suitable for W‐band communication systems. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2205–2211, 2014
A 10.5‐GHz divide‐by‐3 injection‐locked frequency divider with enhanced locking range by even‐harmonic phase tuning in 0.18 μm BiCMOS
Authors: Lee Sanghun , Jang Sunhwan , Nguyen Cam
Published: July 2014

A fully integrated 10.5‐GHz divide‐by‐3 (1/3) injection‐locked frequency divider (ILFD) that can provide extra locking range is presented. The ILFD consists of a previously measured on‐chip 10.5‐GHz voltage controlled oscillator (VCO) functioning as an injection source, a 1/3 ILFD core, and an output inverter buffer. A phase tuner implemented using an asymmetric inductor is proposed to increase the locking range through even‐harmonic phase tuning. With a fixed internal injection signal power of only −18 dBm, a 25% enhancement in the locking range from 12 to 15 MHz is achieved with the proposed phase tuning. The proposed even‐harmonic phase tuning can be used to provide extra locking range to those achieved by other techniques. The proposed integrated 1/3 ILFD has a frequency tuning range of 3.3–4.2 GHz. It is realized using a 0.18‐μm BiCMOS process, occupies 0.6 mm × 0.7 mm, and consumes 10.6 mA while the ILFD core alone only consumes 6.15 mA from 1.8‐V supply voltage. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2249–2252, 2014
Optimal size of uniform aperture for near‐field penetration through lossy medium
Authors: Razavi Aidin , Yang Jian
Published: July 2014

We present our investigations on the optimal size of uniform antenna aperture for the maximum near‐field penetration of microwave signals through lossy materials. Penetration ability of an antenna through a certain depth in a lossy material depends on how much the radiated power from the antenna is focused at that depth. A figure of merit, the near‐field 3 dB beam radius, is used to define this focusing. Empirical formula to calculate the minimum 3 dB radius and its location are provided in the article. Verification of the results has been carried out by simulations using a commercial electromagnetic solver. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2301–2304, 2014
Designs of spiral slot antennas with dual‐frequency operation
Authors: Row Jeen‐Sheen , Chen Li‐Ting
Published: July 2014

Dual‐frequency slot antennas with different polarization combinations are studied in this article. The antenna is a single‐arm spiral slot fed by a microstrip line. A comparison between the circular polarization (CP) design methods of a shorted ring slot antenna and a spiral slot antenna is first made. By the comparison results, a design for dual‐frequency CP spiral slot antennas is then drawn. Moreover, it is found that, by rotating the spiral slot, the polarization senses at the two operating frequencies can be varied among three different combinations, including (left‐handed CP, right‐handed CP), (right‐handed CP, left‐handed CP), and (linear polarization, linear polarization). Simulation and experimental results for the performances of the antenna operating at each polarization combination are shown in detail. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2294–2297, 2014
Low‐ringing and reduced‐cost step recovery diode based UWB pulse generators for GPR applications
Authors: Kamal Athar , Bhattacharya Amitabha , Tamrakar Maruti , Roy Chayan
Published: July 2014

Low‐ringing and reduced‐cost pulse generators for ultrawideband applications using step recovery diode (SRD) have been reported in this article. The circuits generate Gaussian pulses of 170 ps pulse width and a minimal ringing of −22 dB and monocycles of 401 ps duration and high fractional bandwidth of 162%. Cost‐reduction is mainly attributed to the resistive attenuator and single SRD used. Negligible change in circuits' performance was witnessed for repetition rate from 1 to 100 MHz which makes it apt for low to medium range ground penetrating radar applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2289–2294, 2014
SAR study of antennas in wireless communication terminals
Authors: Shi Yan , Sun Hao , Liang Chang‐Hong
Published: July 2014

A new normalized evaluation method has been proposed to compare specific absorption rates (SARs) of four representative terminal antennas at wireless communication LTE band 7 including loop antenna, monopole antenna, planar inverted‐f antenna (PIFA), and zeroth‐order resonant (ZOR) antenna based on the composite left‐ and right‐hands transmission line. According to analyses of the effects of human tissue on antenna performance, input power is normalized by return loss and radiation efficiency of terminal antennas. Simulation and measurement results show that the normalized SARs of four antennas for 4G USB dongle application are reasonably ranked in order from small to large as PIFA, ZOR antenna, loop antenna, monopole antenna, which means that PIFA has most homogeneous near‐zone power distribution, whereas monopole antenna has the worst one among four antennas. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2361–2365, 2014
Design of a high‐gain ultra‐wideband planar dipole antenna using LC tanks, chip resistors, and dual‐layer frequency selective surface
Authors: Shadrokh Shahin , Yu Yiqiang , Jolani Farid , Chen Zhizhang
Published: July 2014

In this article, a low‐profile, high‐gain, ultra‐wideband (UWB) planar dipole antenna is presented for radar imaging applications. The antenna is loaded with open complementary double concentric split‐hexagonal‐ring resonators (LC tank) and chip resistors, and backed with a novel double‐layer frequency selective surface reflector for gain enhancement. A broadband microstrip to parallel‐plate transformer is designed as the feeding structure of the antenna to provide impedance matching and balanced‐to‐unbalanced transition. The measurement results show the proposed antenna operates over the frequency bandwidth of 0.65–3.8 GHz with S11< −10 dB (VSWR) and smooth gains in the range of 6.2–9 dBi. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2369–2373, 2014
Experimental and simulated study of dual‐band chiral metamaterials with strong optical activity
Authors: Min‐Hua Li , Lin‐yan Guo , He‐Lin Yang
Published: July 2014

A dual‐band planar chiral metamaterial (CMM) with strong optical activity is experimentally constructed by twisted split rings. Resonant frequencies with strong optical activity are around 7.9 and 8.9 GHz for right circularly polarized (RCP) and 9.95 and 10.9 GHz for left circularly polarized (LCP) wave, respectively. In particular, the two independent eigenfrequencies depend sensitively on the twist angles, which can offer a convenient approach in building multiband or tunable CMMs. With the twist angle increased from 0° to 90°, the resonant frequencies play an obvious blueshift for RCP wave and redshift for LCP wave, respectively. Current distributions are also studied, which demonstrate that the observed resonances are linked to the excitation of multimodal standing current waves. Microwave experiments are performed to successfully realize these ideas and results are in good agreement with the numerical results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2381–2385, 2014
Electromagnetic analysis of graphene based tunable waveguide resonators
Authors: Ilić Andjelija Ž. , Budimir Djuradj
Published: July 2014

The electromagnetic analysis of the proposed graphene based tunable waveguide resonators for submillimeter‐wave applications is presented. Simple design based on the conventional E‐plane resonator is considered. The desired tunability up to 5% is provided by the change of the effective resonator length. Simulation results are presented to validate the argument. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2385–2388, 2014
Wavelength tunable single longitudinal mode fiber laser pinned to 25 GHz spacing
Authors: Yang Chengliang , Xia Li , Wang Yuanwu , Liu Deming
Published: July 2014

A wavelength tunable single longitudinal mode (SLM) fiber laser is demonstrated with a high power Er‐Yb codoped fiber amplifier (EDFA) used as gain medium. A fiber Fabry‐Perot filter and a bandpass filter ensure single wavelength lasing. To realize SLM operation, a section of unpumped EDF in a Sagnac loop is adopted as a saturable absorber, which results in a self‐induced FBG (frequency band gap) with an ultranarrow bandwidth. The proposed laser is very stable and in SLM operation. The signal to noise ratio is measured about 65 dB. The output laser has a tuning range over 30 nm from 1535 to1565 nm. The tuning step of the proposed laser is 0.20 nm pinned to the ITU grid. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2404–2406, 2014
An X‐band substrate integrated waveguide attenuator
Authors: Eom Dong‐Sik , Lee Hai‐Young
Published: July 2014

An X‐band substrate integrated waveguide (SIW) attenuator is presented for the first time. To gain the desired attenuation level, a resistive π‐network was structured using standard surface‐mount device resistors while retaining a predefined mode transition and impedance matching condition. The attenuator prototype features the measure of attenuation level (−1, −3, and −5dB) across 8.04–11.12 GHz frequency range. The attenuator may contribute to design of a genuine SIW circuit. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2446–2449, 2014
Adaptive grouping for the higher‐order multilevel fast multipole method
Authors: Borries Oscar , Jørgensen Erik , Meincke Peter , Hansen Per Christian
Published: July 2014

An alternative parameter‐free adaptive approach for the grouping of the basis function patterns in the multilevel fast multipole method is presented, yielding significant memory savings compared to the traditional Octree grouping for most discretizations, particularly when using higher‐order basis functions. Results from both a uniformly and nonuniformly meshed scatterer are presented, showing how the technique is worthwhile even for regular meshes, and demonstrating that there is no loss of accuracy in spite of the large reduction in memory requirements and the relatively low computational cost. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2451–2456, 2014
Liquid metal patch antenna and antenna array for WLAN applications
Authors: Semkin Vasilii , Platonov Oleg , Kyrö Mikko , Räisänen Antti V.
Published: July 2014

The concept of a reconfigurable patch antenna array is presented in this article. Configurability is achieved using liquid metal alloy which fills necessary milled channels in the antenna structure. A single patch antenna and three patch antenna array are simulated and measured in this work. Matching and radiation properties in the frequency range from 4 to 10 GHz are presented. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2462–2464, 2014
A case study of student achievement in a secondary charter school
Authors: Hung Li‐Ching , Badejo Folashade , Bennett Jo
Published: July 2014

The quality of student learning and achievement in public schools has become a matter of public discourse and policy, thus led to the establishment of charter school concept. However, there are controversial reports on the academic performances of charter schools, inadequate information on their instructional practices, and the learning experiences of students who attend secondary charter schools. The purpose of this case study was to find correlations on instructional practices, learning activities, learner motivation, and their perception of learning at a secondary charter school that serves students in various at‐risk situations that have not been described in existing research. Using a case study, the qualitative research identified instructional practices and connection between motivation, learning, and student's perception of learning. Data collected from 3 administrators, 13 teachers, and 30 students through interviews, observations of classrooms, and observation of social behaviors in the breakfast program, were subjected to inductive analysis. Findings revealed that the secondary charter school utilizes mission‐oriented instructional practices to meet the educational needs of every student. Flexible school structure, rewards, support systems, positive reinforcement, and ardent student teacher relationships were motivating factors responsible for student achievement. Students expressed satisfaction with their learning experiences at the school and able to progress to higher grade levels.
Facile synthesis of high‐molecular‐weight acid‐labile polypeptides using urethane derivatives
Authors: Wong Shirley , Kwon Young Jik
Published: July 2014

Polypeptides have received noticeable attention in the biomedical field due to their structural versatility and biomimetic properties. Particularly, polypeptides that are responsive to biological stimuli, such as mildly acidic extracellular and intracellular conditions, have great potential as delivery carriers for therapeutics. However, synthesis of high‐molecular‐weight acid‐labile peptides is often daunting due to highly restrictive polymerization conditions and limitations in preserving acid‐degradable functional groups. For instance, the popular N‐carboxyanhydride (NCA) ring‐opening polymerization (ROP) is efficient, but acid‐labile NCA monomers are difficult to synthesize and store. In this study, acid‐labile polypeptides with high molecular weights were synthesized under mild, permissive conditions using carboxylated urethane derivative monomers which are stable for ease of handling. The polymerization was successful in various organic solvents at room temperature, and did not require additional energy or initiation to drive the formation of NCA intermediates. The polymerization was also rapid enough to be independent of inert atmosphere. The strategy explored here to synthesize high‐molecular‐weight acid‐labile polypeptides offers significant advantages including facile synthesis of acid‐labile urethane derivative monomers that are stable, even in contact with moisture, and fast polymerization under easily achievable conditions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 280–286
Pharmacokinetics and toxicology of a fibroblast activation protein (FAP)‐activated prodrug in murine xenograft models of human cancer
Authors: Brennen W. Nathaniel , Rosen D. Marc , Chaux Alcides , Netto George J. , Isaacs John T. , Denmeade Samuel R.
Published: July 2014

BACKGROUND

As carcinoma progresses, the stroma undergoes a variety of phenotypic changes, including the presence of carcinoma‐associated fibroblasts (CAFs) that express fibroblast activation protein (FAP). FAP is a post‐prolyl endopeptidase whose expression in a healthy adult is largely restricted to the cancer‐associated stroma. FAP‐targeted prodrugs with a 100‐fold greater therapeutic window over the parent compound were previously generated.

METHODS

Prodrugs and non‐cleavable controls were incubated in the presence of FAP. Plasma and tumor half‐lives (t1/2) of the full‐length and active forms of the prodrugs were determined using LCMS. Biodistribution studies of prodrug activation were performed. Histopathological analysis of tissues from treated animals were compared to vehicle‐treated controls. Toxicity and efficacy studies were performed in human breast (MDA‐MB‐231 and MCF‐7) and prostate (LNCaP) cancer xenografts models.

RESULTS

These FAP‐activated prodrugs have a significantly slower clearance from tumor tissue than the circulation (∼12 vs. ∼4.5 hr). Micromolar concentrations of active drug persist in the tumor. Active drug is detected in non‐target tissues; however, histopathologic evaluation reveals no evidence of drug‐induced toxicity. A FAP‐activated prodrug (ERGETGP‐S12ADT) inhibits tumor growth in multiple human breast and prostate cancer xenograft models. The anti‐tumor effect is comparable to that observed with docetaxel, but results in significantly less toxicity.

CONCLUSION

FAP‐activated prodrugs are a viable strategy for the management of prostate and other cancers. These prodrugs exhibit less toxicity than a commonly used chemotherapeutic agent. Further refinement of the FAP cleavage site for greater specificity may reduce prodrug activation in non‐target tissues and enhance clinical benefit. Prostate 74: 1308–1319, 2014. © 2014 Wiley Periodicals, Inc.
miR‐34a is an intracellular and exosomal predictive biomarker for response to docetaxel with clinical relevance to prostate cancer progression
Authors: Corcoran Claire , Rani Sweta , O'Driscoll Lorraine
Published: July 2014

BACKGROUND

Docetaxel‐resistance limits successful treatment of castration resistant prostate cancer. We previously demonstrated that extracellular vesicles (exosomes) may play a role in regulating docetaxel resistance. Here, we investigated intracellular and extracellular (exosomal) miRNAs related to docetaxel resistance.

METHODS

Following global miRNA profiling of cell line models of docetaxel‐resistance and their corresponding exosomes, we investigated the clinical relevance of four selected miRNAs (miR‐598, miR‐34a, miR‐146a, miR‐148a) in four publically available clinical cohorts representing both primary and advanced disease in tissue and urine specimens. One of these miRNAs, miR‐34a was selected for functional evaluation by miRNA inhibition and over‐expression in vitro. We further assessed the panel of miRNAs for their combined clinical relevance as a biomarker signature by examining their common predicted targets.

RESULTS

A strong correlation was found between the detection of miRNAs in exosomes and their corresponding cells of origin. Of the miRNAs chosen for further validation and clinical assessment, decreased miR‐34a levels showed substantial clinical relevance and so was chosen for further analysis. Manipulating miR‐34a in prostate cancer cells confirms that this miRNA regulates BCL‐2 and may, in part, regulate response to docetaxel. When combined, these miRNAs are predicted to regulate a range of common mRNA targets, two of which (e.g., SNCA, SCL7A5) demonstrate a strong relationship with prostate cancer progression and poor prognosis.

CONCLUSIONS

This study supports the extracellular environment as an important source of minimally invasive predictive biomarkers representing their cellular origin. Using miR‐34a as example, we showed that biomarkers identified in this manner may also hold functional relevance. Prostate 74: 1320–1334, 2014. © 2014 The Authors. The Prostate, published by Wiley Periodicals, Inc.
Pharmaceutical care: the blueprint for modern pharmacy
Authors: Baines Darrin
Published: July 2014

In our series on the history of prescribing policy, Dr Darrin Baines traces how successive governments have attempted to curb drug costs. Here, he describes the proposals for greater pharmacist involvement in patient care.