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D E Orallo, S G Bertolotti, M S Churio
The properties and photochemical and photophysical behavior of the mycosporine-like amino acids (MAAs) shinorine and porphyra-334 were experimentally evaluated in solutions of direct ionic micelles as simple biomimicking environments. The preferential partition of the natural molecules in the aqueous phase of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium chloride (CTAC) micellar systems is confirmed. Although the proton dissociation of the carboxylic groups in the MAAs is slightly inhibited in CTAC solutions, the molecules are predicted to be in the form of zwitterions in all the explored media around physiological pH...
May 26, 2017: Photochemical & Photobiological Sciences
Jaewon Yang, Florian Wiesinger, Sandeep Kaushik, Dattesh Shanbhag, Thomas A Hope, Peder E Z Larson, Youngho Seo
Purpose: In brain positron emission tomography/magnetic resonance imaging (PET/MRI), the major challenge of zero-echo-time (ZTE)-based attenuation correction (ZTAC) is the misclassification of air/tissue/bone mixtures or their boundaries. Our study aimed to evaluate a sinus/edge corrected (SEC) ZTAC (ZTACSEC), relative to an "uncorrected (UC)" ZTAC (ZTACUC) and a computed tomography (CT) atlas-based attenuation correction (ATAC). Materials and Methods: Whole-body fluorodeoxyglucose PET/MRI scans were performed for twelve patients, following PET/CT scans...
May 4, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Amjad M Ahmed, Mohamed E Ebid, Amr M Ajlan, Mouaz H Al-Mallah
BACKGROUND: Non-enhanced computed tomography (CT) is a valuable modality in the diagnosis of non-alcoholic fatty liver disease (NAFLD). However, it is not clear if low-dose CT attenuation correction (CTAC) scans have the same accuracy to diagnose NAFLD. Our aim is to evaluate the diagnostic accuracy of low-dose CTAC in the diagnosis of NAFLD using non-enhanced CT as a gold standard. METHODS: A total of 864 patients who underwent a clinically indicated hybrid nuclear imaging scanning between May 2011 and April 2014 were included in the study...
May 3, 2017: Abdominal Radiology
Irene Russo Krauss, Riccardo Imperatore, Augusta De Santis, Alessandra Luchini, Luigi Paduano, Gerardino D'Errico
HYPOTHESIS: Catanionic vesicles based on large-scale produced surfactants represent a promising platform for the design of innovative, effective and relatively inexpensive nano-vehicles for a variety of actives. Structural, dynamic and functional behavior of these aggregates is finely tuned by the molecular features of their components and can be opportunely tailored for their applications as drug carriers. EXPERIMENTS: Here we investigate the aggregates formed by CTAC and SDS, two of the most diffused surfactants, by means of Dynamic Light Scattering, Small Angle Neutron Scattering and Electron Paramagnetic Resonance spectroscopy (EPR)...
April 12, 2017: Journal of Colloid and Interface Science
Nao Fukai, Shinya Kitagawa, Hajime Ohtani
We have recently demonstrated the separation of neutral and water-insoluble linear synthetic polymers in nonaqueous capillary zone electrophoresis (NACZE) using a cationic surfactant of cetyltrimethylammonium chloride (CTAC). In this study, eight ionic surfactants were investigated for the separation of four synthetic polymers (polystyrene, polymethylmethacrylates, polybutadiene, and polycarbonate); only three surfactants (CTAC, dimethyldioctadecylammonium bromide, and sodium dodecylsulfate) caused their separation...
April 18, 2017: Electrophoresis
Ivana Išgum, Bob D de Vos, Jelmer M Wolterink, Damini Dey, Daniel S Berman, Mathieu Rubeaux, Tim Leiner, Piotr J Slomka
BACKGROUND: We investigated fully automatic coronary artery calcium (CAC) scoring and cardiovascular disease (CVD) risk categorization from CT attenuation correction (CTAC) acquired at rest and stress during cardiac PET/CT and compared it with manual annotations in CTAC and with dedicated calcium scoring CT (CSCT). METHODS AND RESULTS: We included 133 consecutive patients undergoing myocardial perfusion (82)Rb PET/CT with the acquisition of low-dose CTAC at rest and stress...
April 4, 2017: Journal of Nuclear Cardiology: Official Publication of the American Society of Nuclear Cardiology
Jarmo Teuho, Virva Saunavaara, Tuula Tolvanen, Terhi Tuokkola, Antti Karlsson, Jouni Tuisku, Mika Teräs
In positron emission tomography (PET), corrections for photon scatter and attenuation are essential for visual and quantitative consistency. Magnetic resonance attenuation correction (MRAC) is generally conducted by image segmentation and assignment of discrete attenuation coefficients, which offers limited accuracy compared to computed tomography attenuation correction (CTAC). Potential inaccuracies in MRAC may affect scatter correction, as the attenuation image (µ-map) is used in single scatter simulation (SSS) to calculate the scatter estimate...
March 23, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Viviane Lutz-Bueno, Marianne Liebi, Joachim Kohlbrecher, Peter Fischer
In ionic surfactant micelles, basic interactions among distinct parts of surfactant monomers, their counterion, and additives are fundamental to tuning molecular self-assembly and enhancing viscoelasticity. Here, we investigate the addition of sodium salicylate (NaSal) to hexadecyltrimethylammonium chloride and bromide (CTAC and CTAB) and 1-hexadecylpyridinium chloride and bromide (CPyCl and CPyBr), which have distinct counterions and headgroup structures but the same hydrophobic tail. Different contrasts are obtained from small-angle neutron scattering (SANS), which probes differences between the nucleus of atoms, and X-rays SAXS, which probes differences in electron density...
March 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Harshali Bal, Vladimir Y Panin, Guenther Platsch, Michel Defrise, Charles Hayden, Chloe Hutton, Benjamin Serrano, Benoit Paulmier, Michael E Casey
Calculating attenuation correction for brain PET imaging rather than using CT presents opportunities for low radiation dose applications such as pediatric imaging and serial scans to monitor disease progression. Our goal is to evaluate the iterative time-of-flight based maximum-likelihood activity and attenuation correction factors estimation (MLACF) method for clinical FDG brain PET imaging. FDG PET/CT brain studies were performed in 57 patients using the Biograph mCT (Siemens) four-ring scanner. The time-of-flight PET sinograms were acquired using the standard clinical protocol consisting of a CT scan followed by 10 min of single-bed PET acquisition...
April 7, 2017: Physics in Medicine and Biology
Nobuhiro Yada, Hideo Onishi, Masahiro Miyai, Kentarou Ozasa, Takashi Katsube, Keiichi Onoda, Masuo Haramoto, Yasushi Yamamoto, Shuhei Yamaguchi, Hajime Kitagaki
We evaluated a novel normal database (NDB) generated using single photon emission computed tomography (SPECT) data obtained from healthy brains by using a SPECT/CT system, analyzed using a resolution recovery (RR) technique applied to the three-dimensional stereotactic surface projection (3D-SSP) technique. We used a three-dimensional ordered subset expectation maximization method (3D-OSEM) with applied scatter correction (SC), attenuation correction, and RR to reconstruct the data. We verified the accuracy of the novel NDB's values (Z, extent, and error scores), and compared the novel NDB to the 3D-SSP technique by using simulated misery perfusion-related patient data from a conventional NDB...
February 4, 2017: Radiological Physics and Technology
Pan Wang, Shuai Pei, Muhan Wang, Youguo Yan, Xiaoli Sun, Jun Zhang
Transformation from linear to branched wormlike micelle generally results in the dramatic loss of viscoelasticity. In this study, adopting Coarse-grained molecular dynamics simulation, the conformational transformation was studied in a binary system of cetyltrimethylammonium chloride (CTAC) and sodium salicylate (Nasal). A gross conformation diagram of micelle at different CTAC concentrations and molar ratios of CTAC/Nasal indicates that the branched structure could form at zeta potential lower than 32mV. Further, the dynamic process displays that four sequential stages, approaching, forming salt bridge, yielding stalk, and coalescing together, involve in this transformation...
May 15, 2017: Journal of Colloid and Interface Science
Andrew P Leynes, Jaewon Yang, Dattesh D Shanbhag, Sandeep S Kaushik, Youngho Seo, Thomas A Hope, Florian Wiesinger, Peder E Z Larson
PURPOSE: This study introduces a new hybrid ZTE/Dixon MR-based attenuation correction (MRAC) method including bone density estimation for PET/MRI and quantifies the effects of bone attenuation on metastatic lesion uptake in the pelvis. METHODS: Six patients with pelvic lesions were scanned using fluorodeoxyglucose (18F-FDG) in an integrated time-of-flight (TOF) PET/MRI system. For PET attenuation correction, MR imaging consisted of two-point Dixon and zero echo-time (ZTE) pulse sequences...
March 2017: Medical Physics
Duan Bin, Beibei Yang, Ke Zhang, Caiqin Wang, Jin Wang, Jiatai Zhong, Yue Feng, Jun Guo, Yukou Du
In this study, galvanic replacement provides a simple route for the synthesis of PdAg hollow nanoflower structures by using the Ag-seeds as sacrificial templates in the presence of l-ascorbic acid (reductant) and CTAC (capping agent). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and EDS mapping were used to characterize the as-prepared PdAg hollow nanoflower catalysts, where they were alloyed nanoflower structures with hollow interiors...
October 10, 2016: Chemistry: a European Journal
Xuzhu Zhang, Andrzej Poniewierski, Aldona Jelińska, Anna Zagożdżon, Agnieszka Wisniewska, Sen Hou, Robert Hołyst
The equilibrium and rate constants of molecular complex formation are of great interest both in the field of chemistry and biology. Here, we use fluorescence correlation spectroscopy (FCS), supplemented by dynamic light scattering (DLS) and Taylor dispersion analysis (TDA), to study the complex formation in model systems of dye-micelle interactions. In our case, dyes rhodamine 110 and ATTO-488 interact with three differently charged surfactant micelles: octaethylene glycol monododecyl ether C12E8 (neutral), cetyltrimethylammonium chloride CTAC (positive) and sodium dodecyl sulfate SDS (negative)...
October 4, 2016: Soft Matter
Shan Zhou, Jianhua Li, Kyle D Gilroy, Jing Tao, Chunlei Zhu, Xuan Yang, Xiaojun Sun, Younan Xia
It remains a challenge to synthesize Ag nanocubes in an aqueous system, although the polyol process was successfully adopted more than one decade ago. Here, we report an aqueous method for the synthesis of Ag nanocubes with an average edge length of 35-95 nm. It involves the formation of AgCl octahedra by mixing CF3COOAg with cetyltrimethylammonium chloride, followed by the nucleation and growth of Ag nanocrystals in the presence of ascorbic acid (AA) and FeCl3. The Fe(3+)/Fe(2+) redox pair is responsible for the removal of multiply twinned seeds through oxidative etching...
November 22, 2016: ACS Nano
Yuki Inoue, Yo Tsutamoto, Daiki Muko, Kazuaki Nanamura, Tsuyoshi Sawada, Yasuro Niidome
Spherical gold nanoparticles with cationic surfaces were prepared in hexadecyltrimethylammonium (CTA(+)) chloride (CTAC) and CTA(+) bromide (CTAB) solutions. In a CTAC solution, ascorbic acid reduction of gold ions (AuCl4(-)) induced spontaneous nucleation of gold clusters, which resulted in the formation of small gold nanoparticles (<5 nm). In a CTAB solution, the combination of ascorbic acid and AuBr4(-) induced low spontaneous nucleation, and therefore controllable crystal growth of seed particles was possible...
2016: Analytical Sciences: the International Journal of the Japan Society for Analytical Chemistry
Francisco A O Carvalho, Fernanda R Alves, Marcel Tabak
Glossoscolex paulistus hemoglobin (HbGp) is an oligomeric multisubunit protein with molecular mass of 3600kDa. In the current study, the interaction of sodium dodecyl sulfate (SDS) and cetyl trimethylammonium chloride (CTAC) surfactants with the monomer d and the whole oxy-HbGp, at pH 7.0, was investigated. For pure monomer d solution, SDS promotes the dimerization of subunit d, and the monomeric and dimeric forms have sedimentation coefficient values, s20,w, around 2.1-2.4 S and 2.9-3.2 S, respectively. Analytical ultracentrifugation (AUC) and isothermal titration calorimetry (ITC) data suggest that up to 26 DS(-) anions are bound to the monomer...
November 2016: International Journal of Biological Macromolecules
Taku Uchibe, Masahiro Miyai, Nobuhiro Yata, Masuo Haramoto, Yasushi Yamamoto, Megumi Nakamura, Hajime Kitagaki, Yasuyuki Takahashi
The discovery of NM530c with a cadmium-zinc-telluride detector (CdZnTe-SPECT) is superior to the conventional Anger-type SPECT with a sodium-iodide detector (NaI-SPECT) in terms of sensitivity and spatial resolution. However, in the clinical example, even in CdZnTe-SPECT, a count decrease in myocardium due to the attenuation of the gamma ray is an issue. This study was conducted to evaluate the effect of computed tomography attenuation correction (CTAC) in CdZnTe-SPECT with the help of external CT. We evaluated the revision effect of uniformity, influence by the difference in attenuation distance, contrast ratio, an uptake rate using the heart phantom...
July 2016: Nihon Hoshasen Gijutsu Gakkai Zasshi
Chunxiao Xi, Yahui Song, Jihui Zhang, Dongmei Zhang, Haibing Xia
Currently, seed-mediated growth method is the dominant strategy for synthesis of silver nanoparticles (Ag NPs) with different sizes. However, it is complicated for the researchers with limited chemistry-training. In this work, monodisperse, quasi-spherical Ag NPs with different sizes were successfully produced in high yield by adding a trace amount of NaBH4 solution into the mixtures of AgNO3, ascorbic acid and cetyltrimethylammonium chloride (CTAC) as surfactants. It was found that the sizes of as-prepared Ag NPs can be tuned from 20 nm to 50 nm by adjusting the NaBH4 concentration at optimal pH (about 6...
June 2016: Journal of Nanoscience and Nanotechnology
Nobuhiro Yada, Hideo Onishi
OBJECTIVES: In this study, we aimed to validate the accuracy of computed tomography-based attenuation correction (CTAC), using the bilinear scaling method. METHODS: The measured attenuation coefficient (μm) was compared to the theoretical attenuation coefficient (μt), using four different CT scanners and an RMI 467 phantom. The effective energy of CT beam X-rays was calculated, using the aluminum half-value layer method and was used in conjunction with an attenuation coefficient map to convert the CT numbers to μm values for the photon energy of 140 keV...
2016: Asia Oceania Journal of Nuclear Medicine & Biology
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