Distribution by Scientific Domains

Selected Abstracts

Teaching image processing: A two-step process

Clarence Han-Wei Yapp
Abstract An interactive program for teaching digital image processing techniques is presented in this article. Instead of heavy programming tasks and mathematical functions, students are led step by step through the exercises and then allowed to experiment. This article evaluates the proposed program and compares it with existing techniques. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 211,222, 2008; Published online in Wiley InterScience (; DOI 10.1002/cae.20149 [source]

Harmonization of light scatter and fluorescence flow cytometry profiles obtained after staining peripheral blood leucocytes for cell surface-only versus intracellular antigens with the Fix & PermÔ reagent,,§

CYTOMETRY, Issue 1 2010
Elaine Sobral da Costa
Abstract Staining for intracellular markers with the Fix & PermÔ reagent is associated with variations in the scatter properties of leucocytes, limiting automated analysis of flow cytometry (FCM) data. Here, we investigated those variables significantly contributing to changes in the light scatter, autofluorescence, and bcl2 staining characteristics of peripheral blood (PB) leucocytes, after fixation with Fix & PermTM. Our major aim was to evaluate a new mathematical approach for automated harmonization of FCM data from datafiles corresponding to aliquots of a sample treated with cell-surface-only versus Fix & Perm intracellular staining techniques. Overall, neither the anticoagulant used nor sample storage for <24 h showed significant impact on the light scatter and fluorescence properties of PB leucocytes; similarly, the duration of the fixation period (once >15 min were used) had a minimum impact on the FCM properties of PB leucocytes. Conversely, changes in cell/protein concentrations and the fixative/sample (vol/vol) ratio had a clear impact on the light scatter features of some populations of leucocytes. Accordingly, lower cell/protein concentrations were associated with lower scatter values, particularly for the neutrophils. Such changes could be partially corrected through the use of higher fixative to sample volume ratios. Despite the variable changes detected between aliquots of the same sample treated with cell surface-only versus intracellular staining procedures, the new mathematical approach here proposed and evaluated for automated harmonization of common parameters in both datafiles, could correct the FCM profiles of leucocytes derived from cells undergoing conventional fixation/permeabilization procedures, and made them indistinguishable from those corresponding to aliquots of the same sample treated with cell-surface-only staining techniques. © 2009 Clinical Cytometry Society [source]

Reactions of [Et4N][Tp*W(,3 -S)(,-S)2­(CuSCN)2] with Nitrogen Donor Ligands: Syntheses, Structures, and Third-Order Nonlinear Optical Properties

Zhen-Hong Wei
Abstract Reactions of the preformed cluster [Et4N][Tp*W(,3 -S)(,-S)2(CuSCN)2] (1) with pyridine (py), 4,4,-bipyridine (4,4,-bipy), or 1,3-bis(4-pyridyl)propane (bpp) led to the formation of three neutral [Tp*W(,3 -S)(,-S)2Cu2]-based compounds [Tp*W(,3 -S)(,-S)2Cu2(SCN)(py)2] (2), [{Tp*W(,3 -S)(,-S)2Cu2(SCN)}2(4,4,-bipy)]·3.5H2O (3·3.5H2O), and [Tp*W(,3 -S)(,-S)2Cu2(SCN)(bpp)]2 (4), respectively. Compounds 2,4 were characterized by elemental analysis, IR spectra, UV/Vis spectra, 1H NMR, and X-ray analysis. There are two linkage isomers [Tp*W(,3 -S)(,-S)2Cu2(SCN)(py)2] and [Tp*W(,3 -S)(,-S)2Cu2(NCS)(py)2], each of which has its own enantiomeric pair in the crystal of 2. Compound 3 has a double butterfly-shaped structure in which two [Tp*W(,3 -S)(,-S)2Cu2(SCN)] fragments are linked with a single 4,4,-bipy bridge. For 4, the two butterfly-shaped [Tp*W(,3 -S)(,-S)2Cu2(SCN)] fragments are interconnected by a pair of bpp bridges. The third-order nonlinear optical (NLO) performances of 2,4 in DMF were also investigated by Z -scan techniques.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

The N -Acylated Derivatives of Parent Complex [{(,-SCH2)2NH}Fe2(CO)6] as Active Site Models of Fe-Only Hydrogenases: Synthesis, Characterization, and Related Properties

Li-Cheng Song
Abstract A series of N -acylated diiron azadithiolate complexes as H-cluster models was synthesized and structurally characterized. Treatment of parent complex [{(,-SCH2)2NH}Fe2(CO)6] (A) with 2-chloroacetic acid in the presence of dicyclohexylcarbodiimide or with 2-chloroacetyl chloride in the presence of Et3N gave N -chloroacetyl complex [{(,-SCH2)2NC(O)CH2Cl}Fe2(CO)6] (1). Further treatment of 1 with MeC(O)SK afforded N -acetylthioacetyl complex [{(,-SCH2)2NC(O)CH2SC(O)Me}Fe2(CO)6] (2). N -Ethoxylcarbonylacetyl complex [{(,-SCH2)2NC(O)CH2CO2Et}Fe2(CO)6] (3) and N-heterocyclic complexes [{(,-SCH2)2NC(O)C4H3Y-2}Fe2(CO)6] (4, Y = O; 5, Y = S) were produced by reactions of A with EtO2CCH2C(O)Cl, 2-furancarbonyl chloride, and 2-thiophenecarbonyl chloride in the presence of pyridine or Et3N. Similarly, N -malonyl complex [{Fe2(CO)6(,-SCH2)2NC(O)}2CH2] (6) and N -carbonylbenzaldehyde complex [{(,-SCH2)2NC(O)C6H4CHO- p}Fe2(CO)6] (7) could be obtained by reaction of A with malonyl dichloride in the presence of pyridine and with p -CHOC6H4C(O)Cl in the presence of Et3N. More interestingly, further reaction of 7 with PhCHO and pyrrole in a 1:3:4 molar ratio in the presence of BF3·OEt2 followed by p -chloranil yielded the first light-driven type of model complex containing an N -carbonylphenylporphyrin moiety [{(,-SCH2)2NC(O)(TPP)}Fe2(CO)6] (8, TPP = tetraphenylporphyrin group). Whereas the molecular structures of 2, 5, and 7 were established by X-ray crystallography, the electrochemical properties of 2,5 as well as the proton reduction to hydrogen gas catalyzed by 2 and 3 were studied by CV techniques.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Synthesis and Characterization of Cubane-Like Cr4E4 (E = S, Se) Clusters , Molecular Structures of (,5 -RC5H4)4Cr4E4 (E = S, R = MeCO, MeO2C, EtO2C; E = Se, R = H)

Li-Cheng Song
Abstract Treatment of the Cr,Cr singly-bonded dimers [,5 -RC5H4Cr(CO)3]2 (1, R = MeCO; 2, R = MeO2C; 3, R = EtO2C) with excess sulfur in refluxing THF gave the cubane Cr4S4 clusters (,5 -RC5H4)4Cr4S4 (4, R = MeCO; 5, R = MeO2C; 6, R = EtO2C). The cubane Cr4S4 cluster 4 reacted with excess 2,4-dinitrophenylhydrazine to produce the hydrazone derivative [,5,2,4-(NO2)2C6H3NHN=C(Me)C5H4]4Cr4S4 (7). The singly-bonded dimers of [,5 -RC5H4Cr(CO)3]2 (8, R = Me; 9, R = EtO2C), in the presence of excess selenium, reacted similarly to the linear Cr2Se complexes [,5 -RC5H4Cr(CO)2]2Se (10, R = Me; 11, R = EtO2C), which reacted with an equimolar quantity of selenium to afford the cubane Cr4Se4 clusters (,5 -RC5H4)4Cr4Se4 (12, R = Me; 13, R = EtO2C). A particularly interesting phenomenon is the cross-assembled reaction of the linear Cr2Se complexes [,5 -MeC(O)C5H4Cr(CO)2]2Se (14) and [CpCr(CO)2]2Se (15) in the presence of excess selenium in THF that gave rise to a series of cubane Cr4Se4 clusters [,5 -MeC(O)C5H4]nCp4,nCr4Se4 (16, n = 0; 17, n = 1; 18, n = 2; 19, n = 3; 20, n = 4). The possible pathway for the cross-assembled reaction is suggested. Furthermore the new clusters were characterized by elemental analysis and spectroscopy, and in the case of 4,6 and 16 also by X-ray diffraction techniques. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

A Highly Enantioselective Receptor for Carbamoyl Lactic Acid,

Francisco M. Muñiz
Abstract A new receptor based on a 9,9-dimethylxanthene framework was synthesized. Owing to its suitable oxyanion hole structure, this receptor is able to associate carboxylic acids and anions. The introduction of a chiral center provides enantioselective properties to this receptor as a result of its different interactions with both enantiomers of the substrate. The combination of this skeleton with a fluorescent unit such as dansyl allows the detection of small amounts of carboxylic acids by making use of fluorescent techniques.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Improved detection of chromosomal abnormalities in chronic lymphocytic leukemia by conventional cytogenetics using CpG oligonucleotide and interleukin-2 stimulation: A Belgian multicentric study,

Natalie Put
We performed a multicentric study to assess the impact of two different culture procedures on the detection of chromosomal abnormalities in 217 consecutive unselected cases with chronic lymphocytic leukemia (CLL) referred for routine analysis either at the time of diagnosis (n = 172) or during disease evolution (n = 45). Parallel cultures of peripheral blood or bone marrow were set up with the addition of either the conventional B-cell mitogen 12- O -tetradecanoyl-phorbol-13-acetate (TPA) or a combination of CpG oligonucleotide (CpG) and interleukin-2 (IL-2). Cytogenetic analyses were performed on both cultures. Clonal abnormalities were identified in 116 cases (53%). In 78 cases (36%), the aberrant clone was detected in both cultures. Among these, the percentages of aberrant metaphases were similar in both conditions in 17 cases, higher in the CpG/IL-2 culture in 43 cases, and higher in the TPA culture in 18 cases. Clonal aberrations were detected in only one culture, either in CpG/IL-2 or TPA in 33 (15%) and 5 (2%) cases, respectively. Taken together, abnormal karyotypes were observed in 51% with CpG/IL-2 and 38% with TPA (P < 0.0001). Application of FISH (n = 201) allowed the detection of abnormalities not visible by conventional cytogenetic analysis in 80 cases: del(13q) (n = 71), del(11q) (n = 5), +12 (n = 2), del(14q) (n = 1), and del(17p) (n = 1). In conclusion, our results confirm that CpG/IL-2 stimulation increases the detection rate of chromosomal abnormalities in CLL compared with TPA and that further improvement can be obtained by FISH. However, neither conventional cytogenetics nor FISH detected all aberrations, demonstrating the complementary nature of these techniques. © 2009 Wiley-Liss, Inc. [source]

MLL/SEPTIN6 chimeric transcript from inv ins(X;11)(q24;q23q13) in acute monocytic leukemia: Report of a case and review of the literature

Hee-Jin Kim
Rearrangements of the MLL gene on chromosome 11, band q23, are one of the most common genetic changes in acute leukemia. Reciprocal translocation is the most common form of MLL rearrangement, and the partner genes in MLL translocation are notably diverse. Involvement of the SEPTIN6 gene on Xq24 in MLL rearrangements occurs very rarely, with only six cases having been documented in the literature. Of note, the MLL/SEPTIN6 rearrangements in these cases were cryptic or complex, and it was shown that the 5,- MLL/SEPTIN6 -3, transcript resides on the derivative X chromosome rather than on the derivative chromosome 11 as in the majority of cases of MLL translocations. These observations suggested that MLL and SEPTIN6 reside on their respective chromosome loci in reverse orientation, that is, centromere-to-telomere and telomere-to-centromere, respectively. We here report a case of acute monocytic leukemia with inv ins(X;11)(q24;q23q13) in a 29-month-old child. Fluorescence in situ hybridization study revealed the break-apart 5,- MLL segment to be translocated to the derivative X chromosome, and reverse transcriptase,polymerase chain reaction followed by sequencing analysis confirmed the 5,- MLL/SEPTIN6 -3, chimeric transcript. This case is the first to provide direct cytogenetic evidence for the salient nature of the MLL/SEPTIN6 rearrangement. We reviewed clinical and cytogenetic features of all cases of 11q23 and Xq22,24 rearrangements reported up to now, including six cases where the involvement of the SEPTIN6 gene was confirmed by molecular techniques. © 2003 Wiley-Liss, Inc. [source]

Compositional analysis of Yayoi-Heian period ceramics from Okinawa: Examining the potential for provenance study

Scott M. Fitzpatrick
In Okinawa, locally produced pottery dates back to the Initial Jomon period (,6500 14C yr B.P.). Later in time, especially during the Early Yayoi-Heian period (,300 B.C.,A.D. 300), ceramic assemblages appear to contain mainland (Japan) Yayoi pottery. A greater number of these sherds present in Okinawa over time coincide with an increasing amount of interaction with mainland Japan, as evidenced by other exchange items. In this preliminary study, the authors analyzed sherds from several Early Yayoi-Heian period deposits from sites in Okinawa using thin-section petrography and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The objective was to examine the applicability of these techniques for Okinawan ceramic provenance studies, assess intra- and intersite variation in mineralogical and chemical composition, and determine whether some sites exhibited a higher frequency of pottery from one locale versus another that might suggest the importation of pottery from mainland Japan. Results are equivocal, suggesting that the region's geological complexity may inhibit successful provenance study of ceramics using these and possibly other compositional techniques. © 2006 Wiley Periodicals, Inc. [source]

Impact of demographics, tumor characteristics, and treatment factors on swallowing after (chemo)radiotherapy for head and neck cancer

Jacqui Frowen BSpPath (Hons)
Abstract Background This prospective study evaluated the impact of patient demographics, tumor characteristics, and radiotherapy treatment on swallowing before and after radiotherapy or chemoradiotherapy. Methods Eighty-one patients with head and neck cancer were examined using videofluoroscopy swallowing studies (VFSS) before treatment and again at 3 and 6 months after treatment. Results Swallowing was best at baseline, significantly worse 3 months posttreatment, and improved by 6 months posttreatment. Worse swallowing was associated with: living in rural areas; ex-heavy alcohol consumption; hypopharyngeal tumor site; large (particularly T4) tumors; nonconformal radiotherapy; bilateral radiation to the pharynx; and longer radiotherapy fields. Through the use of multiple regression analysis, previous swallowing was determined to be the most common predictor of swallowing outcomes, followed by T classification, alcohol history, and radiotherapy technique. Conclusions The pretreatment and treatment factors that influenced swallowing in this cohort should be considered when planning treatment, in discussing potential side effects with patients, and when developing and testing future treatment techniques. © 2009 Wiley Periodicals, Inc. Head Neck, 2010 [source]

Prospective evaluation of the retrograde percutaneous translaryngeal tracheostomy (Fantoni procedure) in a surgical intensive care unit: Technique and results of the Fantoni tracheostomy

Ralf Konopke MD
Abstract Background. Controversy surrounds the safety and practicality of the retrograde percutaneous translaryngeal tracheostomy (Fantoni procedure) compared with other percutaneous methods. Methods. We used the Fantoni tracheostomy for 245 patients in our intensive care unit (ICU) over a period of 3 years 6 months and conducted a prospective analysis. Results. We are able to report a low incidence of complications (1.2%) with the Fantoni procedure. Advantages of the method are reduced tissue trauma and optimal adaptation of the stoma to the cannula, leading to less stomal bleeding and fewer infectious complications. We observed no procedure-related mortality. Under mandatory bronchoscopic control, proper puncture location and cannula placement are ensured, which prevents tracheal wall injury and paratracheal placement of the cannula. Conclusions. Our experience shows that the major advantage of the use of the Fantoni tracheostomy is the retrograde dilatation of the stoma, which prevents serious complications compared with other techniques. © 2005 Wiley Periodicals, Inc. Head Neck28: 355,359, 2006 [source]

Past and future directions in x-ray computed tomography (CT)

Frank Natterer
We give a short account of the history of CT from motion tomography in the early 1930's to sprial CT. We discuss the physical and the mathematical background. Finally we give an outlook on possible future developments of CT and related techniques. © 2002 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 175,187, 2002; Published online in Wiley InterScience ( DOI 10.1002/ima.10021 [source]

High-level synthesis by dynamic ant

Rachaporn Keinprasit
In this article, a new algorithm called dynamic ant is introduced. It was a combination of ant colony optimization (ACO) techniques and the dynamic niche sharing scheme. The interesting point of this algorithm is that it is implemented easily and could be well matched with existing design algorithms by adding the heuristic weights to speed up the algorithm. The algorithm uses the problem state structure as in the reinforcement-learning algorithm, but the storage explosion is prevented by means of the pheromone trail. This algorithm was investigated for the data path design problem of high-level synthesis of which has a large number of design steps and design techniques. © 2004 Wiley Periodicals, Inc. [source]

Simple yet powerful techniques for optimization of horizontal recursion steps in Gaussian-type two-electron integral evaluation algorithms

Marcin Makowski
Abstract Simple heuristic rules are given that allow optimization of the performance of horizontal recursion steps present in schemes for calculation of two electron integrals are given. The number of floating point operations and computer timings are compared with the other algorithmic approaches to the problem. It is shown that the presented rules lead to substantial computational savings when compared with the standard implementation and may be also used succesfully instead of the algorithms based on full tree search techniques. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source]

From lumped-element circuits to monolithic integrated circuits: A contribution to RF and microwave mixer design

Peter Waldow
Abstract This article deals with the mixer design for UHF-, microwave- and millimeter-wave applications. Thereby, several aspects such as the chosen technology (lumped elements, hybrid- or monolithic integration) and the applied transmission line (printed circuits, strip-, slot- or coplanar line) are considered. During the course of this contribution, the authors point out the developments in mixer design from lumped-element circuits to monolithic integrated circuits on the example of research activities in Duisburg and Kamp-Lintfort, Germany. The results of these scientific investigations, regarding both the theoretical and experimental aspects, show the feasibility of the proposed techniques. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

Lower critical solution temperature determination of smart, thermosensitive N -isopropylacrylamide- alt -2-hydroxyethyl methacrylate copolymers: Kinetics and physical properties

Mohammad M. Fares
Abstract The lower critical solution temperatures (LCSTs) were verified and determined for different molar feed ratios of N -isopropylacrylamide (NIPAAm) and 2-hydroxyethyl methacrylate (HEMA) monomers with ultraviolet spectroscopy and differential scanning calorimetry techniques. Increases in the NIPAAm monomer content played a crucial role in the LCST, which increased up to 36.7°C at 50 mol %. However, a further increase in the NIPAAm monomer content steadily reduced the LCST, which decreased to 33°C at 100 mol % NIPAAm [i.e., pure poly(N -isopropylacrylamide)]. The rate of copolymerization, assessed by the conventional conversion (%),time method, and the apparent activation energies were determined. The reactivity ratios of the monomers, determined by the Kelen,Tudos and Fineman,Ross techniques, together with the results of an equation, showed that the copolymer which formed was an alternating copolymer. The Q,e values for the NIPAAm monomer were determined. The equation showed the linear Arrhenius behavior of ln(r1r2) versus the reciprocal of the temperature (where r1 and r2 are the reactivity ratios of NIPAAm and HEMA, respectively): the activation energy difference [i.e., (E12 + E21) , (E11 + E22), where E12, E21, E11, and E22 are various activation energies] was found to be ,109 kJ/mol. The copolymers were characterized with 1H-NMR, 13C-NMR, Fourier transform infrared, ultraviolet,visible, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy techniques. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

A new spiroketal from Aspergillus terreus, an endophytic fungus in Opuntia ficusindica Mill

Shao-Hua Wu
Abstract A new spiroketal, named aspergiketal (1) was isolated from the culture broth of Aspergillus terreus, an endophytic fungus in the stems of the plant Opuntia ficusindica Mill., together with two known compounds, physcion (2) and asterric acid (3). Their structures were elucidated by spectroscopic methods including 2D-NMR techniques. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

New phenyl-ethanediols from the culture broth of Boletus edulis

Wan-Qiu Yang
Abstract A new phenyl-ethanediol, (1S)-(4-acetylphenyl)-1, 2-ethanediol (1), and a new natural product, (1S)-(3-ethenylphenyl)-1, 2-ethanediol (2), were isolated from the culture broth of the basidiomycete Boletus edulis together with three related known compounds, 1-(4-ethylphenyl)-1, 2-ethanediol (3), 1-(3-ethylphenyl)-1, 2-ethanediol (4) and 1-(3-formylphenyl)-ethanone (5). Their structures were elucidated by spectroscopic methods including extensive 2D-NMR techniques. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Why I (really) became a therapist

Albert Ellis
This article describes how the author really became a therapist and worked on his own social and performance anxiety. He was at first a follower of liberal psychoanalysis, but, in successfully using in vivo desensitization on himself, he overcame his anxiety and became highly constructivist. He finally created rational emotive behavior therapy, the pioneering cognitive-behavior therapy; integrated it with emotional-evocative and experiential methods; and used it to cope with much criticism he received about his active-directive techniques. © 2005 Wiley Periodicals, Inc. J Clin Psychol/In Session 61: 945,948, 2005. [source]

Systematic and statistical error in histogram-based free energy calculations

Mark N. Kobrak
Abstract A common technique for the numerical calculation of free energies involves estimation of the probability density along a given coordinate from a set of configurations generated via simulation. The process requires discretization of one or more reaction coordinates to generate a histogram from which the continuous probability density is inferred. We show that the finite size of the intervals used to construct the histogram leads to quantifiable systematic error. The width of these intervals also determines the statistical error in the free energy, and the choice of the appropriate interval is therefore driven by the need to balance the two sources of error. We present a method for the construction of the optimal histogram for a given system, and show that the use of this technique requires little additional computational expense. We demonstrate the efficacy of the technique for a model system, and discuss how the principles governing the choice of discretization interval could be used to improve extended sampling techniques. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1437,1446, 2003 [source]

Percutaneous Mitral Valve Repair for Mitral Regurgitation

Mitral regurgitation (MR) associated with, ischemic, and degenerative (prolapse) disease, contributes to left ventricular (LV) dysfunction due to remodeling, and LV dilation, resulting in worsening of MR. Mitral valve (MV) surgical repair has provided improvement in survival, LV function and symptoms, especially when performed early. Surgical repair is complex, due to diverse etiologies and has significant complications. The Society for Thoracic Surgery database shows that operative mortality for a 1st repair is 2% and for re-do repair is 4 times that. Cardiopulmonary bypass and cardiac arrest are required. The attendant morbidity prolongs hospitalization and recovery. Alfieri simplified mitral repair using an edge-to-edge technique which subsequently has been shown to be effective for multiple etiologies of MR. The MV leaflers are typically brought together by a central suture producing a double orifice MV without stenosis. Umana reported that MR decreased from grade 3.6 +/,0.5 to0.8 +/,0.4 (P < 0.0001)and LV ejection fraction increased from 33 +/,13% to 45 +/,11%(P = 0.0156). In 121 patients, Maisano reported freedom from re-operation of 95 +/,4.8% with up to 6 year follow-up. Oz developed a MV "grasper" that is directly placed via a left ventriculotomy and coapts both leaflets which are then fastened by a graduated spiral screw. An in-vitro model using explanted human valves showed significant reduction in MR and in canine studies, animals followed by serial echo had persistent MV coaptation. At 12 weeks the device was endothelialized. These promising results have paved the way for a percutaneous or minimally invasive off pump mitral repair. Evalve has developed catheter-based technology, which, by apposing the edges of a regurgitant MV, results in edge-to-edge repair. Release of the device is done after echo and fluoroscopic evaluation under normal loading conditions. If the desired effect is not produced the device can be repositioned or retrieved. Animal studies show excellent healing, with incorporation of the device into the leaflets at 6,10 weeks with persistent coaptation. Another percutaneous approach has been to utilize the proximity of the coronary sinus (CS) to the mitral annulus (MA). Placement of a self-compressing device in the CS along the region of the posterior MA has, in canine models, reduced MR and addresses the issues of MA dilation and its contribution to MR. Ongoing studies are underway for both techniques. (J Interven Cardiol 2003;16:93,96) [source]

Lorenzo's oil, adrenoleukodystrophy, and the blood, brain barrier

E. J. Murphy
Adrenoleukodystrophy is a rapid, progressive demyelinating disease affecting the CNS that is characterized by large increases in plasma and tissue very long saturated fatty acids (VLCFA). Lorenzo's oil (LO), consisting of erucic (22:1 n-9) and oleic (18:1 n-9) acid in a triglyceride form, is a dietary therapy effective in reducing plasma and tissue VLCFA. Despite the decreased VLCFA, clinical studies indicated that LO failed to stop the progressive demyelination, suggesting that erucic acid, the active component of LO, did not cross the BBB. We addressed this question by infusing [14-14C] 22:1 n-9 (170 ,Ci/kg) into male rats using two different infusion paradigms. The radiotracer was infused (i.v.) into awake, adult male rats over a 10-min period or infused (i.c.v.) into the fourth ventricle over a 7-day period using an osmotic mini-pump. Brains were removed from the cranium, frozen in liquid nitrogen, lipids extracted, and separated using standard techniques. [1-14C] 20:4 n-6 was infused (i.v.) and used as a positive control. Following i.v. infusion, 0.011% of the erucic acid was extracted by the brain, compared to 0.055% of the arachidonic acid. About 60% of the brain erucic acid was found in the aqueous fraction compared to 30% for arachidonic acid. Further, erucic acid was targeted to cholesteryl ester and triacylglyceride pools, whereas arachidonic acid was targeted to phospholipid pools. In animals infused i.c.v., 0.078% of the dose was taken up and about 60% of the erucic acid was targeted to phospholipid pools. These results clearly demonstrate that erucic acid crosses the BBB, similar to arachidonic acid, and is incorporated into specific lipid pools. Acknowledgements:, This work was supported by The Myelin Project. [source]

Synthesis of bulk MgB2 superconductors by pulsed electric current

AICHE JOURNAL, Issue 7 2006
A. M. Locci
Abstract A preparation method to simultaneously synthesize and consolidate bulk MgB2 superconductors from Mg and B commercial elemental powders by means of the spark plasma sintering technique is reported. The influence of process parameters on sintering process dynamics as well as product characteristics, determined by transport and magnetic measurements, is investigated. The superconducting properties of the obtained samples, and particularly the critical current density, are comparable or better than those corresponding to other MgB2 preparation techniques. Thus, the superconductive properties of the bulk MgB2 materials synthesized in this work are suitable for selected applications, such as magnetic levitation, magnetic screening, and fault current limiters. It should be finally noted that the proposed method represents a particularly rapid preparation route as compared to other techniques. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source]

Non-enzymatic glycation of chondrocyte-seeded collagen gels for cartilage tissue engineering

Rani Roy
Abstract Collagen glycated with ribose (250 mM) in solution (pre-glycation) and as a gel (post-glycation) was seeded with chondrocytes and the effects of glycation on chondrocyte matrix assembly in culture were determined. Pre-glycation enhanced GAG accumulation significantly over controls at both 2 and 4 weeks (p,<,0.05), although at both time points there were no statistical differences in cell number between pre-glycated and control gels. The increased proteoglycan accumulation was shown to be in part due to significantly increased GAG retention by the pre-glycated constructs (p,<,0.05). Total collagen content in these pre-glycated gels was also significantly higher than unglycated gels at 4 weeks (p,<,0.05). With post-glycation of collagen gels, chondrocyte number and GAG accumulation were all significantly lower than controls (p,<,0.05). Post-glycation also inhibited GAG retention by the constructs (p,<,0.05). Given these results, pre-glycation may be an improved processing method for collagen gels for tissue engineering techniques. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1434,1439, 2008 [source]

A strategy for synthesis of ion-bonded amphiphilic miktoarm star copolymers via supramolecular macro-RAFT agent

Dairen Lu
Abstract Amphiphilic supramolecular miktoarm star copolymers linked by ionic bonds with controlled molecular weight and low polydispersity have been successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using an ion-bonded macromolecular RAFT agent (macro-RAFT agent). Firstly, a new tetrafunctional initiator, dimethyl 4,6-bis(bromomethyl)-isophthalate, was synthesized and used as an initiator for atom transfer radical polymerization (ATRP) of styrene to form polystyrene (PSt) containing two ester groups at the middle of polymer chain. Then, the ester groups were converted into tertiary amino groups and the ion-bonded supramolecular macro-RAFT agent was obtained through the interaction between the tertiary amino group and 2-dodecylsulfanylthiocarbonylsulfanyl-2-methyl propionic acid (DMP). Finally, ion-bonded amphiphilic miktoarm star copolymer, (PSt)2 -poly(N -isopropyl-acrylamide)2, was prepared by RAFT polymerization of N -isopropylacrylamide (NIPAM) in the presence of the supramolecular macro-RAFT agent. The polymerization kinetics was investigated and the molecular weight and the architecture of the resulting star polymers were characterized by means of 1H-NMR, FTIR, and GPC techniques. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5805,5815, 2008 [source]

Living radical photopolymerization induced grafting on thiol,ene based substrates

Sirish K. Reddy
Abstract The formation of reactive substrates with iniferter-mediated living radical photopolymerization is a powerful technique for surface modification, which can readily be used to facilitate the incorporation of a variety of surface functionalities. In this research, the photopolymerization kinetics of novel bulk thiol,ene systems have been compared with those of typical acrylate and methacrylate systems when polymerized in the presence of the photoiniferter p -xylene bis(N,N -diethyl dithiocarbamate) (XDT). In the presence of XDT, the thiol,ene systems photopolymerize more quickly than the traditional acrylate and methacrylate systems by one to two orders of magnitude. Fourier transform infrared spectroscopy has been used to monitor the photografting kinetics of various monomers on dithiocarbamate-functionalized surfaces. Furthermore, this technique has been used to evaluate surface-initiation kinetics and to emphasize the influence of bulk substrate properties on grafting kinetics. Finally, photopatterning has been demonstrated on a dithiocarbamate-incorporated thiol,ene substrate with conventional photolithographic techniques. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2134,2144, 2005 [source]

Densely grafted polyisocyanides synthesized by two types of polymerization techniques

Yanqing Tian
Abstract A series of novel polyisocyanide- graft -polystyrenes and polyisocyanide- graft -[polystyrene- block -poly(butyl acrylate)]s were synthesized through the grafting-through and grafting-from routes with two types of living polymerization techniques: polymerization with the Pd,Pt ,-ethynediyl dinuclear complex as the initiator and catalyst for the polyisocyanide backbone and atom transfer radical polymerization for the grafted side chain. Through the introduction of a chiral center at the side chain of the polyisocyanide backbone, helical grafted and graft block polyisocyanides were prepared through the grafting-from method. All of the obtained polymers exhibited polydispersities in the range of 1.07,1.41. This might have been the first time grafted polyisocyanides were prepared, especially helical grafted polyisocyanides, through the operation of two living polymerization techniques. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1871,1880, 2003 [source]

SPIDER: A decade of measuring ultrashort pulses

M.E. Anderson
Abstract It was ten years ago in Rochester, New York that the first SPIDER was built. This simple acronym belies the subtleties of its inner workings; Spectral Phase Interferometry for Direct Electric-field Reconstruction (the "f" in field conveniently missed the cut) is a device that measures ultrashort pulses, utilizing spectral shearing interferometry and directly recovering the spectral phase. The very first SPIDER apparatus occupied nearly half an optical table, used a scanning monochromator, and had no computerized inversion routine. In the intervening decade, SPIDER has grown up. It has found a strong foothold in ultrafast laboratories throughout the world. Multiple groups have found useful new applications with this vital measurement tool, while others have contributed to the improvement of SPIDER itself, reaching to ever shorter pulses, new wavelength regimes, and making devices more sensitive, robust, smaller and faster. It also adapts to a field of research that changes rapidly. It was first designed to track and quantify the remaining spectral phase in a pulse to perfect its compression. In ten years, with the advent of pulse shapers, the real benefits of field diagnostics are becoming apparent. We have shifted away from the race towards the shortest IR pulse to a wide use of complex shaped pulses in almost every spectral range from far IR to XUV. But the quest of the shortest pulse is not over and new compression techniques utilize really broad spectra that are highly structured. All these applications provide new challenges for characterization techniques. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

Design of a planar ultra-wideband miniature monopole antenna for wireless USB dongle devices

Yu-Chia Chang
Abstract This article proposes a 3.1,5 GHz ultra-wideband antenna, defined by a ,10 dB return loss. The simplified planar antenna structures, compact size, and low profile make it profitable to the application of the embedded antenna in wireless universal serial bus dongle devices. The slit shape on the monopole radiator is tuned for miniature antenna size. A parasitic stub on the ground is adopted to increase antenna bandwidth for achieving 3.1,5 GHz impedance bandwidth. To reduce manufacturing cost and practical fabrication, we also propose a simplified rectangular antenna structure. It is found that wideband characteristics of the simplified rectangular structure antenna are similar to that of semicircular base structure. Finally, the antenna prototypes are fabricated and the antenna characteristics are measured. The radiation patterns are omnidirectional in azimuth cut. Moreover, the S -parameter of antenna characteristics has been measured. The consistency between the simulated results and the measurement results confirms the practicability of these techniques. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1013,1016, 2010; Published online in Wiley InterScience ( DOI 10.1002/mop.25121 [source]

Radar pulse interleaving for multi-target tracking

Moustafa Elshafei
Abstract In a multifunction radar, the maximum number of targets that can be managed or tracked is an important performance measure. Interleaving algorithms developed to operate radars exploit the dead-times between the transmitted and the received pulses to allocate new tracking tasks that might involve transmitting or receiving pulses, thus increasing the capacity of the system. The problem of interleaving N targets involves a search among N! possibilities, and suboptimal solutions are usually employed to satisfy the real-time constraints of the radar system. In this paper, we present new tight 0,1 integer programming models for the radar pulse interleaving problem and develop effective solution methods based on Lagrangian relaxation techniques. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004. [source]