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1.
Carlos A. ávila-Orta Zoe V. Qui?ones-Jurado Miguel A. Waldo-Mendoza Erika A. Rivera-Paz Víctor J. Cruz-Delgado José M. Mata-Padilla Pablo González-Morones Ronald F. Ziolo 《Materials》2015,8(11):7900-7912
Isotactic polypropylenes (iPP) with different melt flow indexes (MFI) were used to fabricate nanocomposites (NCs) with 10 wt % loadings of multi-wall carbon nanotubes (MWCNTs) using ultrasound-assisted extrusion methods to determine their effect on the morphology, melt flow, and electrical properties of the NCs. Three different types of iPPs were used with MFIs of 2.5, 34 and 1200 g/10 min. Four different NC fabrication methods based on melt extrusion were used. In the first method melt extrusion fabrication without ultrasound assistance was used. In the second and third methods, an ultrasound probe attached to a hot chamber located at the exit of the die was used to subject the sample to fixed frequency and variable frequency, respectively. The fourth method is similar to the first method, with the difference being that the carbon nanotubes were treated in a fluidized air-bed with an ultrasound probe before being used in the fabrication of the NCs with no ultrasound assistance during extrusion. The samples were characterized by MFI, Optical microscopy (OM), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), electrical surface resistivity, and electric charge. MFI decreases in all cases with addition of MWCNTs with the largest decrease observed for samples with the highest MFI. The surface resistivity, which ranged from 1013 to 105 Ω/sq, and electric charge, were observed to depend on the ultrasound-assisted fabrication method as well as on the melt flow index of the iPP. A relationship between agglomerate size and area ratio with electric charge was found. Several trends in the overall data were identified and are discussed in terms of MFI and the different fabrication methods. 相似文献
2.
Comparison of 2-dimensional and 3-dimensional acquisition for 18F-FDG PET oncology studies performed on an LSO-based scanner. 总被引:1,自引:0,他引:1
Martin A Lodge Ramsey D Badawi Richard Gilbert Pablo E Dibos Bruce R Line 《Journal of nuclear medicine》2006,47(1):23-31
Three-dimensional (3D) PET acquisition has the potential to reduce image noise but the advantage of 3D PET for studies outside the brain has not been well established. To compare the performance of 2-dimensional (2D) and 3D acquisition for whole-body (18)F-FDG applications, a series of patient studies were performed using a lutetium oxyorthosilicate (LSO)-based tomograph. METHODS: Comparative 2D and 3D images were acquired for 27 oncology patients using an LSO-based tomograph. Data acquisition (350-650 keV, 6 ns) started 99 +/- 12 min (mean +/- SD) after injection of 624 +/- 76 MBq (18)F-FDG. Bias caused by tracer redistribution and decay was eliminated by acquiring dynamic data over a single-bed position using a protocol that alternated between septa-in and septa-out modes (2D, 3D, 2D, 3D, 2D, 3D). Frames were combined to form 8 statistically independent sinograms: four 2D replicates (105 s) and four 3D replicates (90 s). The different frame durations in 2D and 3D compensated for the different number of overlapping bed positions required for an 85-cm whole-body study. Images were reconstructed with either 2D or fully 3D ordered-subsets expectation maximization (2 iterations and 8 subsets; 2D 6-mm gaussian, 3D 5- and 6-mm gaussian). Image target-to-background ratio was assessed by dividing the lesion maximum by the mean within a neighboring background region. Image noise was assessed by applying background regions of interest to the replicate images and calculating the within-patient coefficient of variation. RESULTS: The difference in target-to-background ratio between the 2D and 3D images, when they were filtered with 6-mm and 5-mm gaussian filters, respectively, was not highly statistically significant (P = 0.16). The mean ratio of 3D to 2D image values was 0.94 with 95% limits of agreement of 0.63-1.41. The within-patient coefficients of variation for the 2D and 3D images were 13% +/- 15% and 9% +/- 10%, respectively (P = 0.0005). CONCLUSION: Under conditions of matched target to-to-background ratios, the 3D mode was found to produce images with significantly less variability than the 2D mode. These data provide support for the use of 3D acquisition with LSO detectors to reduce scan times in whole-body (18)F-FDG applications. 相似文献
3.
4.
Robotic-assisted heller myotomy versus laparoscopic heller myotomy for the treatment of esophageal achalasia: multicenter study 总被引:3,自引:0,他引:3
Santiago Horgan M.D. Carlos Galvani M.D. Maria V. Gorodner M.D. Pablo Omelanczuck M.D. Fernando Elli M.D. Federico Moser M.D. Luis Durand M.D. Miguel Caracoche M.D. Jorge Nefa M.D. Sergio Bustos M.D. Phillip Donahue M.D. Pedro Ferraina M.D. 《Journal of gastrointestinal surgery》2005,9(8):1020-1030
Laparoscopic Heller myotomy (LHM) has become the standard treatment option for achalasia. The incidence of esophageal perforation
reported is about 5%–10%. Robotically assisted Heller myotomy (RAHM) is emerging as a safe alternative to LHM. Data comparing
the two approaches are scant. The aim of this study was to compare RAHM with LHM in terms of efficacy and safety for treatment
of achalasia. A total of 121 patients underwent surgical treatment of achalasia at three institutions. A retrospective review
of prospectively collected perioperative data was performed. Patients were divided into two groups: group A (RAHM), 59 patients,
and group B (LHM), 62 patients. All the operations were completed using minimally invasive techniques. There were 63 women
and 58 men, with a mean age of 45 ±19 years (14–82 years). Fifty-one percent of patients in group A and 95% of patients in
group B reported weight loss. Duration of symptoms was equal for both groups. Dysphagia was the main complaint in both groups
(P = NS). There was no difference in preoperative endoscopic treatment in both groups (44% versus 27%, P = NS). Operative
time was significantly shorter for LHM in the first half of the experience (141 ± 49 versus 122 ± 44 minutes, P < .05). However,
in the last 30 cases there was no difference in operative time between the groups (P = NS). Intraoperative complications (esophageal
perforation) were more frequent in group B (16% versus 0%). The incidence of postoperative heartburn did not differ by group.
There were no deaths. At 18 and 22 months, 92% and 90% of patients had relief of their dysphagia. This study suggests that
RAHM is safer than LHM, because it decreases the incidence of esophageal perforation to 0%, even in patients who had previous
treatment. At short-term follow-up, relief of dysphagia was equally achieved in both groups.
Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18,
2005 (oral presentation).
This study was supported in part by a grant provided by Intuitive Surgical, Inc. and Ethicon Endo-Surgery, Inc. 相似文献
5.
María Luz Montesinos Manuel Castellano-Muoz Pablo García-Junco-Clemente Rafael Fernndez-Chacn 《Brain Research Reviews》2005,49(2):416-428
In neurons, a network of endocytic proteins accomplishes highly regulated processes such as synaptic vesicle cycling and the timely internalization of intracellular signaling molecules. In this review, we discuss recent advances on molecular networks created through interactions between proteins bearing the Eps15 homology (EH) domain and partner proteins containing the Asn–Pro–Phe (NPF) motif, which participate in important aspects of neuronal function as the synaptic vesicle cycle, the internalization of nerve growth factor (NGF), the determination of neuronal cell fate, the development of synapses and the trafficking of postsynaptic receptors. We discuss novel functional findings on the role of intersectin and synaptojanin and then we focus on the features of an emerging family of EH domain proteins termed EHDs (EH domain proteins), which are important for endocytic recycling of membrane proteins. 相似文献
6.
Carlos Bada Nilton Yhuri Carreazo Juan Pablo Chalco Luis Huicho 《Revista paulista de medicina》2007,125(3):150-154
CONTEXT AND OBJECTIVE: Many children with acute lower respiratory tract infections (ALRI) present to the emergency ward with concurrent wheezing. A chest x-ray is often requested to rule out pneumonia. We assessed inter-observer agreement in interpreting x-rays on such children. DESIGNS AND SETTING: Prospective consecutive case study at Instituto de Salud del Ni?o, Lima, Peru. METHODS: Chest x-rays were obtained from eligible children younger than two years old with ALRI and concurrent wheezing who were seen in the emergency ward of a nationwide pediatric referral hospital. The x-rays were read independently by three different pediatric residents who were aware only that the children had a respiratory infection. All the children had received inhaled beta-adrenergic agonists before undergoing chest x-rays. Lobar and complicated pneumonia cases were excluded from the study. RESULTS: Two hundred x-rays were read. The overall kappa index was 0.2. The highest individual kappa values for specific x-ray findings ranged from 0.26 to 0.34 for rib horizontalization and from 0.14 to 0.31 for alveolar infiltrate. Inter-observer variation was intermediate for alveolar infiltrate (kappa 0.14 to 0.21) and for air bronchogram (kappa 0.13 to 0.23). Reinforcement of the bronchovascular network (kappa 0.10 to 0.16) and air trapping (kappa 0.05 to 0.20) had the lowest agreement. CONCLUSIONS: There was poor inter-observer agreement for chest x-ray interpretation on children with ALRI and concurrent wheezing seen at the emergency ward. This may preclude reliable diagnosing of pneumonia in settings where residents make management decisions regarding sick children. The effects of training on inter-observer variation need further studies. 相似文献
7.
A high-quality distance preserving output representation is provided to the neural gas (NG) network. The nonlinear mapping is determined concurrently along with the codebook vectors. The adaptation rule for codebook positions in the projection space minimizes a cost function that favors the trustworthy preservation of the local topology. The proposed visualization method, called OVI-NG, is an enhancement over curvilinear component analysis (CCA). The results show that the mapping quality obtained with OVI-NG outperforms the original CCA, in terms of the trustworthiness, continuity, topographic function and topology preservation measures. 相似文献
8.
Antonio Vidaller Fernando Guadarrama Luis Llorente Juan Pablo Méndez Fernando Larrea Antonio R. Villa Donato Alarcón-Segovia 《Journal of clinical immunology》1992,12(3):210-215
We studied NK cell function in eight patients with pathological hyperprolactinemia by measuring51Cr release by K562 cells exposed to their mononuclear cells and found it decreased compared to normal controls (P<0.01). Bromocriptine (BrC) treatment corrected NK function but also made it more efficient at 12:1 than at 25:1 or 50:1 effector:target ratios (ANOVA;P=0.01). The study of NK cell function in agarose revealed that its decrease in hyperprolactinemia is due to their low active binding to target cells, active killing, and recycling capacity. BrC tended to correct them but also increased recycling capacity to levels higher than those of controls (P<0.05). Sequential studies in three hyperprolactinemic patients before and after BrC showed correction of NK function within 1 week but its increased efficiency at the 12:1 effector:target ratio required 8 weeks. We conclude that hyperprolactinemia decreases NK cell function. BrC corrects this by decreasing prolactin levels but also makes NK function more efficient by increasing the capacity of NK cells to recycle after killing. 相似文献
9.
Jesus Benito-Ruiz Angel Navarro-Monzonis Adelina Piqueras Pablo Baena-Montilla 《Microsurgery》1994,15(2):105-115
Vein grafts have been used for nerve repair in experimental and clinical studies. However, some concerns about their collapsability and the presence of valves which could block axonal growth have been put forth. We propose a modification to eliminate these potential problems by turning the vein inside out, obtaining an “invaginated” vein graft. We performed an experimental study on 61 adult Wistar rats, divided into 3 groups: control (non-operated) (n = 11); immediate repair, with 3 subgroups: invaginated vein graft (n = 10), vein graft (n = 10), and nerve graft (n = 10); and delayed repair, with 2 subgroups: invaginated vein graft (n = 10) and nerve graft (n = 10). Delayed repair was performed 3 to 4 weeks following division of the nerve. Electromyographical (EMG) assessment was performed in all operated animals at 2, 4, and 6 months after immediate reconstruction, and at 1 and 4 months after delayed repair. At the end of the study, all nerves were excised and a morphometric analysis was performed. We conclude that vein grafts are as useful as nerve grafts in immediate and delayed nerve repair, as there were no significant functional or histologic differences. We found no significant differences between invaginated vein grafts and non-invaginated vein grafts. However, electrophysiological results were slightly superior in the former. Regenerated axons were small, grouped in minifascicles with thin myelin sheaths. The venous adventitia did not interfere with axonal growth. © 1994 Wiley-Liss, Inc. 相似文献
10.