9,050 research outputs found
MRI Directed Magnevist Effective to Study Toxicity of Gd-Doped Mesoporous Carbon Nanoparticles in Mice Model
No full textChun Zhang,1,2 Changzhou Shi,1 Pengzhao Chang,1 Shuang Bian,1,2 Bangbang Li,1 Jingjing Li,1,2 Pingfu Hou2,3 1School of Medical Imaging, Xuzhou Medical University, Xuzhou, 221004, People’s Republic of China; 2Department of Radiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, 221006, People’s Republic of China; 3Cancer Institute, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, People’s Republic of ChinaCorrespondence: Pingfu Hou; Jingjing Li, Email [email protected]; [email protected]: Magnetic resonance imaging (MRI) has been a valuable and widely used examination technique in clinical diagnosis and prognostic efficacy evaluation. The introduction of MRI contrast agent (CA) improves its sensitivity obviously, particularly with the development of nano-CA, which presents higher contrast enhancement ability. However, systematical evaluation of their toxicity is still limited, hampering their further translation in clinics.Methods: In this paper, to systematically evaluate the toxicity of nano-CA, Gd-doped mesoporous carbon nanoparticles (Gd-MCNs) prepared by a one-step hard template method were introduced as a model and clinically used MRI CA, Magnevist (Gd-DTPA) as control. Their in vitro blood compatibility, cellular toxicity, DNA damage, oxidative stress, inflammation response as well as in vivo toxicity and MR imaging behaviors were studied and compared.Results: The experimental results showed that compared with Gd-DTPA, Gd-MCNs displayed negligible influence on the red blood cell shape, aggregation, BSA structure, macrophage morphology and mitochondrial function. Meanwhile, limited ROS and inflammatory cytokine production also illustrated the cellular compatibility of Gd-MCNs. For in vivo toxicity evaluation, Gd-MCNs presented acceptable in vivo biosafety even under 12 times injection for 12 weeks. More importantly, at the same concentration of Gd, Gd-MCNs displayed better contrast enhancement of tumor than Gd-DTPA, mainly coming from its high MRI relaxation rate which is nearly 9 times that of Gd-DTPA.Conclusion: In this paper, we focus on the toxicity evaluation of MRI nano-CA, Gd-MCNs from different angles. With Gd-DTPA as control, Gd-MCNs appeared to be highly biocompatible and safe nanoparticles that possessed promising potentials for the use of MRI nano-CA. In the future, more research on the long-term genotoxicity and the fate of nanoparticles after being swallowed should be performed.Graphical Abstract: Keywords: MRI, nano-contrast agent, cytotoxicity, tissue toxicity, immunotoxicit
Активаторні центри y монокристалах Li₆Gd(BO₃)₃:Ln (Ln = Ce, Eu)
No full textThe activator centers in Li₆Gd(BO₃)₃ single crystals doped by Ce and Eu have been investigated. Two types of activator centers inLi₆Gd(BO₃)₃ :Ce single crystals and one activator center type in Li₆Gd(BO₃)₃ :Eu ones have been established. The optical characteristics of activator centers have been determined.Изучены активаторные центры в монокристаллах перспективного сцинтилляционно-го материала — литий-гадолиниевого бората Li₆Gd(BO₃)₃ , активированного европием или церием. Методами оптического поглощения, фото- и рентгенолюминесценции установлено наличие двух типов центров в кристаллах Li₆Gd(BO₃)₃ :Ce и одного типа центров в кристаллах Li₆Gd(BO₃)₃ :Eu. Определены характеристики активаторных центров.Вивчено активаторні центри у монокристалах перспективного сцинтиляційного ма-теріала — литій-гадолінієвого бората Li₆Gd(BO₃)₃, активованого європієм та церієм. Методами оптичного поглинання, фото- та рентгенолюмінесценції встановлено наявність двох типів центрів у кристалах Li₆Gd(BO₃)₃ :Ce та одного типу центрів у кристалах Li₆Gd(BO₃)₃
:Eu. Визначено характеристики активаторних центрів
Активаторні центри y монокристалах Li₆Gd(BO₃)₃:Ln (Ln = Ce, Eu)
No full textThe activator centers in Li₆Gd(BO₃)₃ single crystals doped by Ce and Eu have been investigated. Two types of activator centers inLi₆Gd(BO₃)₃ :Ce single crystals and one activator center type in Li₆Gd(BO₃)₃ :Eu ones have been established. The optical characteristics of activator centers have been determined.Изучены активаторные центры в монокристаллах перспективного сцинтилляционно-го материала — литий-гадолиниевого бората Li₆Gd(BO₃)₃ , активированного европием или церием. Методами оптического поглощения, фото- и рентгенолюминесценции установлено наличие двух типов центров в кристаллах Li₆Gd(BO₃)₃ :Ce и одного типа центров в кристаллах Li₆Gd(BO₃)₃ :Eu. Определены характеристики активаторных центров.Вивчено активаторні центри у монокристалах перспективного сцинтиляційного ма-теріала — литій-гадолінієвого бората Li₆Gd(BO₃)₃, активованого європієм та церієм. Методами оптичного поглинання, фото- та рентгенолюмінесценції встановлено наявність двох типів центрів у кристалах Li₆Gd(BO₃)₃ :Ce та одного типу центрів у кристалах Li₆Gd(BO₃)₃
:Eu. Визначено характеристики активаторних центрів
Toetsing ingegoten bekledingen, bestaande kennis en kennisleemten
No full textIn de periode 2001 tot 2003 zijn diverse onderzoeken uitgevoerd naar de stabiliteit van met gietasfalt ingegoten steenzettingen bij ontwerpomstandigheden. Het tot dusver uitgevoerde onderzoek bestond uit drie veldproeven en een aantal bureaustudies. Het uitgevoerde onderzoek heeft het inzicht in het gedrag van een ingegoten bekleding aanzienlijk vergroot. Een ingegoten bekleding blijkt zich gunstiger te gedragen dan tot dusver voar de toetsing op veiligheid werd aangenomen. Nader onderzoek is echter nodig om dit te vertalen in een realistische toetsmethodiek voor ingegoten bekledingen. In dit rapport worden de achtergrond van deze onderzoeken, de bereikte resultaten, de nog bestaande onzekerheden en mogelijk vervolgonderzoek om deze onzekerheden te verkleinen beschreven.Steenzettinge
Dichte bekleding op filter, wateraccumulatie onder bekleding bij een storm.
No full textEen eenvoudig model is opgesteld om de waterstroming in een filterlaag onder een dichte bekleding tijdens golfaanval te beschrijven. In dit model is de mogelijkheid dat de bekleding lokaal los komt van de ondergrond tijdens golfbelasting meegenomen. Met dit model zijn berekeningen uitgevoerd, zowel met geschematiseerde golfdrukken als met gemeten golfdrukken op het talud. Doel van de berekeningen is na te gaan of tijdens een storm de bekleding, welke plaatselijk los komt van de ondergrond, weer gaat aanliggen of dat de waterstroming zodanig is dat dit niet gebeurd (de toestroming van water naar deze plek is gemiddeld groter dan de afstroming, er is dan sprake van een cumulatief effect van de waterstroming). Uit de berekeningen volgt dat dit cumulatief effect waarschijnlijk niet optreedt als de freatische lijn in de filterlaag op hetzelfde niveau of lager ligt dan de stilwaterlijn. Indien de freatische lijn in de filterlaag hoger ligt dan de stilwaterlijn kan dit verschijnsel wel optreden.TAW A4 Asfalttoepassinge
Triaxiale beproeving van asfaltbeton ten behoeve van een constititief model (concept-meetrapport).
No full textINHOUD: 1. INLEIDING 1 2. PRINCIPE-OPZET VAN HET PROEFPROGRAMMA 3 2.1 Modelbepalende proeven 3 2.2 Verificatie proeven 6 2.3 Toegevoegd onderzoek 6 3. MONSTERPREPARATIE 8 4. DE MEETOPSTELLING 10 4.1 De belastingsmodule 10 4.2 De proefcel 10 4.3 De meetconfiguratie 10 4.4 Regeling en data-acquisitie 12 5. DATABEWERKING EN PRESENTATIE 15 6. PROEFBESCHRIJVINGEN 17 6.1 Druk-relaxatie proeven 17 6.2 Trek-relaxatie proeven 28 6.3 Impuls-kruip proeven 36 6.4 Verificatie proeven 43 7. CONCLUSIES EN AANBEVELINGEN 45 8. REFERENTIES 46TAW A4 Asfalttoepassinge
Magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO: First-principles calculations
No full textThe electronic structure and magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO have been investigated using first-principles methods. We show that the magnetic coupling between Gd or Nd ions in the nearest neighbor sites is ferromagnetic. The stability of the ferromagnetic coupling between Gd ions can be enhanced by appropriate electron doping into ZnO Gd system and the room-temperature ferromagnetism can be achieved. However, for ZnO Nd system, the ferromagnetism between Nd ions can be enhanced by appropriate holes doping into the sample. The room-temperature ferromagnetism can also be achieved in the n-conducting ZnO Nd sample. Our calculated results are in good agreement with the conclusions of the recent experiments. The effect of native defects (V-Zn, V-O) on the ferromagnetism is also discussed. (C) 2009 American Institute of Physics. [DOI 10.1063/1.3176490
Influence of Gd and Li additions on the microstructural evolution and mechanical properties of hot-rolled AZ31 alloy
No full textThermomechanical processing and alloying are two common approaches to enhance the mechanical properties of Mg. Thus, the effects of Gd and Li elements, as two elements with various properties, on the microstructure and mechanical properties of a hot-rolled and consequently annealed AZ31 alloy were analyzed. The microstructure and texture was analyzed by scanning electron microscopy and electron back scattered diffraction. Accordingly, the mean grain size of 46 μm in the AZ31 alloy was reduced to 41 and 26 μm in the AZ31–2.9Gd and AZ31–2.3Li alloys, respectively. Grain refinement occurred due to continuous dynamic recrystallization and twinning-induced recrystallization in all of the alloys. Textural evolution showed that neither Gd nor Li could inhibit the occurrence of basal texture. Room temperature mechanical properties were assessed by using the shear punch test (SPT) method. The results exhibited that the strength of the AZ31 alloy was improved from 116 MPa to 139 MPa and 141 MPa by respective additions of Gd and Li. Strength enhancement was mainly attributed to the grain boundary strengthening and second-phase particles hardening. One promising observation was the simultaneous enhancement of shear strength and ductility by the addition of Gd and Li. This observation was ascribed to the more uniform distribution of second-phase particles and lower volume fraction of twins as potential sites for crack initiation. As long as mechanical strength is concerned, results favor the use of Li as alloying element in Mg, especially due to the more noticeable lightweighting potential compared to Gd
Glypican-1-antibody-conjugated Gd-Au nanoclusters for FI/MRI dual-modal targeted detection of pancreatic cancer
No full textXin Huang,1,* Chengqi Fan,2,* Huanhuan Zhu,1 Wenjun Le,1 Shaobin Cui,1 Xin Chen,3 Wei Li,4 Fulei Zhang,4 Yong Huang,4 Donglu Shi,1,5 Zheng Cui,1,6 Chengwei Shao,2 Bingdi Chen1 1The Institute for Translational Nanomedicine, Shanghai East Hospital, The Institute for Biomedical Engineering & Nano Science, Tongji University School of Medicine, Shanghai, China; 2Radiology Department of Changhai Hospital, The Second Military Medical University, Shanghai, China; 3Department of Thyroid Surgery, The First Bethune Hospital of Jilin University, Jilin, China; 4International Joint Cancer Institute, The Second Military Medical University, Shanghai, China; 5The Materials Science & Engineering Program, Department of Mechanical & Materials Engineering, College of Engineering & Applied Science, University of Cincinnati, OH, USA; 6Department of Pathology, Wake Forest University School of Medicine, Winston-Salem, NC, USA *These authors contributed equally to this work Introduction: Pancreatic cancer (PC) has a poor prognosis with high mortality, due to the lack of effective early diagnostic and prognostic tools. Materials and methods: In order to target and diagnose PC, we developed a dual-modal imaging probe using Glypican-1 (GPC-1) antibody conjugated with Gd–Au nanoclusters (NCs; Gd-Au-NC-GPC-1). GPC-1 is a type of cell surface heparan sulfate proteoglycan, which is often highly expressed in PC. The probe was successfully prepared with a hydrodynamic diameter ranging from 13.5 to 24.4 nm. Results: Spectral characteristics showed absorption at 280 nm and prominent emission at 650 nm. Confocal microscopic imaging showed effective detection of GPC-1 highly expressed PC cells by Gd-Au-NC-GPC-1, which was consistent with flow cytometry results. In vitro relaxivity characterization demonstrated that the r1 value of the probe was 17.722 s−1 mM−1 Gd, which was almost 4 times higher compared with that of Gd-diethylenetriaminepentacetate (DTPA; r1 value =4.6 s−1 mM−1 Gd). Gd-Au-NC-GPC-1 exhibited similar magnetic resonance (MR) signals when compared to Gd-DTPA even at lower Gd concentrations. Much higher MR signals were registered in PC cells (COLO-357) compared with normal cells (293T). Furthermore, Gd-Au-NC-GPC-1 could effectively detect PC cells in vivo by dual-modal fluorescence imaging/magnetic resonance imaging (FI/MRI) at 30 minutes postinjection. In addition, Gd-Au-NC-GPC-1 did not show significant biotoxicity to normal cells at tested concentrations both in vitro and in vivo. Conclusion: Gd-Au-NC-GPC-1 has demonstrated to be a promising dual-modal FI/MRI contrast agent for targeted diagnosis of PC. Keywords: pancreatic cancer, Glypican-1, fluorescence imaging, magnetic resonance imaging, Gd–Au NC
Use of infrared light-emitting diodes to determine dosimetric characteristics of MgO:Tb,Gd,Li via the optically stimulated luminescence technique
No full textIn this study, the temperature dependence of Infrared Stimulated Luminescence (IRSL) in MgO:Tb,Gd, Li samples were investigated and the basic dosimetric properties were examined for the radiation dosimetry. Terbium, gadolinium, and lithium doped MgO were synthesized using the solution combustion synthesis method, and the characterization of the material was performed by X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The effects of the dopants were investigated by specifying the radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL-blue stimulation/IRSL-infrared stimulation) curves of the MgO:Tb,Gd, Li phosphor. Decay curves of the light flash vs. time showed that the MgO:Tb,Gd, Li was most readily discharged by infrared stimulation. The temperature dependence of the IRSL samples was investigated between 50 and 230 ?C. The optimized readout temperature was determined as 120 ?C achieving the maximum IRSL intensity. It was shown that there are traps responsible for TL peaks below 200 ?C which could be suggested as the source of the IRSL signals for the studied MgO:Tb,Gd, Li samples. The high-temperature TL peak nearly at 400 ?C was not affected by infrared stimulation and did not contribute to the obtained IRSL signals. The dosimetric properties such as reusability, multi-readability, dose-response, and fading were examined for applicability to radiation dosimetry. The thermal stability of the sample was investigated using the isothermal annealing technique and activation energy and frequency factor of the traps responsible for IRSL signal were estimated as 0.62 eV and 106 Hz, respectively. The MgO:Tb,Gd, Li luminescent has several properties in its favor. It has been shown that the IRSL signals of the Tb, Gd, and Li doped MgO sample can be investigated and examined as a radiation dosimeter
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