| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
- Liu, Zhiying, et al.
(författare)
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On Gate Capacitance of Nanotube Networks
- 2011
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Ingår i: IEEE Electron Device Letters. - : IEEE. - 0741-3106 .- 1558-0563. ; 32:5, s. 641-643
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Tidskriftsartikel (refereegranskat)abstract
- This letter presents a systematic investigation of the gate capacitance C-G of thin-film transistors (TFTs) based on randomly distributed single-walled carbon nanotubes (SWCNTs) in the channel. In order to reduce false counting of SWCNTs that do not contribute to current conduction, C-G is directly measured on the TFTs using a well-established method for MOSFETs. Frequency dispersion of C-G is observed, and it is found to depend on the percolation behavior in SWCNT networks. This dependence can be accounted for using an RC transmission line model. These results are of important implications for the determination of carrier mobility in nanoparticle-based TFTs.
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| 3. |
- Qu, Minni, et al.
(författare)
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Charge-Injection-Induced Time Decay in Carbon Nanotube Network-Based FETs
- 2010
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 31:10, s. 1098-1100
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Tidskriftsartikel (refereegranskat)abstract
- A voltage-pulse method is utilized to investigate the charge-injection-induced time decay of the source-drain current of field-effect transistors with randomly networked single-walled carbon nanotubes (CNTs) as the conduction channel. The relaxation of trapped carriers in the CNT networks can be accounted for by assuming two exponential decays occurring simultaneously. The slow decay is characterized by a time constant comparable to literature data obtained for a carrier recombination in the semiconducting CNTs. The faster decay with a time constant that has a smaller order of magnitude is attributed to the annihilation of trapped carriers in metallic CNTs or at metal-CNT contacts. Both time constants are gate-bias dependent.
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| 4. |
- Chen, Geng, et al.
(författare)
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Experimental Test of the State Estimation-Reversal Tradeoff Relation in General Quantum Measurements
- 2014
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Ingår i: Physical Review X. - 2160-3308. ; 4:5, s. 021043-
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Tidskriftsartikel (refereegranskat)abstract
- When a measurement has limited strength, only partial information, regarding the initial state, is extracted, and, correspondingly, there is a probability to reverse its effect on the system and retrieve the original state. Recently, a clear and direct quantitative description of this complementary relationship, in terms of a tradeoff relation, was developed by Y. K. Cheong and S. W. Lee. [Phys. Rev. Lett. 109, 150402 (2012)]. Here, this tradeoff relation is experimentally verified using polarization-encoded single photons from a quantum dot. Measurement operators representing a complete range, from not affecting the system to a projection to a single polarization state, are realized. In addition, for each measurement operator, an optimal reversal operator is also implemented. The upper bound of the tradeoff relation is mapped to experimental parameters representing the measurement strength. Our results complement the theoretical work and provide a hands-on characterization of general quantum measurements.
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| 5. |
- Li, Jiantong, et al.
(författare)
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Ink-jet printed thin-film transistors with carbon nanotube channels shaped in long strips
- 2011
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 109:8, s. 084915-
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Tidskriftsartikel (refereegranskat)abstract
- The present work reports on the development of a class of sophisticated thin-film transistors (TFTs) based on ink-jet printing of pristine single-walled carbon nanotubes (SWCNTs) for the channel formation. The transistors are manufactured on oxidized silicon wafers and flexible plastic substrates at ambient conditions. For this purpose, ink-jet printing techniques are developed with the aim of high-throughput production of SWCNT thin-film channels shaped in long strips. Stable SWCNT inks with proper fluidic characteristics are formulated by polymer addition. The present work unveils, through Monte Carlo simulations and in light of heterogeneous percolation, the underlying physics of the superiority of long-strip channels for SWCNT TFTs. It further predicts the compatibility of such a channel structure with ink-jet printing, taking into account the minimum dimensions achievable by commercially available printers. The printed devices exhibit improved electrical performance and scalability as compared to previously reported ink-jet printed SWCNT TFTs. The present work demonstrates that ink-jet printed SWCNT TFTs of long-strip channels are promising building blocks for flexible electronics.
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| 6. |
- Liu, Zhiying, et al.
(författare)
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Hysteresis-free thin-film transistors achieved by novel solution-processing of nanotubes/polymer composites
- 2012
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Ingår i: Materials Research Society Spring Meeting 2012, San Francisco, April 9-13, 2012..
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Konferensbidrag (refereegranskat)abstract
- Thin-film transistors (TFTs) based on single-walled carbon nanotubes (SWCNTs) have gained enormous attention in the community of flexible/stretchable electronics. At present, such TFTs often suffer from severe problems including giant hysteresis in their transfer characteristics. With SiO2 as the gate dielectric, extensive investigations have led to generally accepted understanding of the hysteresis as being caused by charge transfer between the SWCNTs and their surroundings including both water molecules bound on the SiO2 surface (Si≡OH) and the water/oxygen molecules in the ambient atmosphere. In order to combat the hysteresis issue, significant efforts have been made by annealing the TFTs in vacuum and separating SWCNTs from SiO2 by deposition of a self-assembled monolayer (SAM) on the SiO2 or passivating the SWCNTs with an organic or inorganic dielectric film. These methods, however, require either processing in inert environment or developing elaborated processes. In the present work, we demonstrate hysteresis-free TFTs based on SWCNT/polymer composite without any complex treatment. The composite consists of SWCNTs and poly-9,9_dioctyl-fluorene-co-bithiophene (F8T2). With the aid of polymer F8T2, SWCNTs can be efficiently dissolved in commonly used solvents thereby forming a uniform composite solution. By soaking a chip with predefined TFT structures on an oxidized Si substrate in the composite solution, direct assembly of the composite on the SiO2 occurs, leading to the formation of a composite thin film in the channel region of the TFTs. Although fabricated using a very simple process, our TFTs exhibit hysteresis-free operation under ambient conditions. It is plausible to suggest that SWCNTs are embedded in the F8T2 matrix with the latter providing an effective shield for the former against the trap sites on the SiO2 and the H2O/O2 molecules in the atmosphere. In comparison to the other reported means aiming at hysteresis reduction, the present method is simple, robust, solution processable, effective, and operable under ambient conditions. In addition, we have found F8T2 to preferentially disperse semiconducting SWCNTs rendering a selective removal of the metallic species in the solution. This selectivity is of paramount importance as it results in high-performance TFTs with both high on-state current (0.1 µA/µm @ channel length = 50 µm) and large on/off current ratio (103-105). The TFTs have also shown significantly improved uniformity and dimensional scalability with a mobility value of 10-20 cm2V-1s-1, which have allowed us to investigate the TFTs using the resultant logic circuits.
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| 7. |
- Liu, Zhiying, et al.
(författare)
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Mobility Extraction for Nanotube TFTs
- 2011
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 32:7, s. 913-915
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Tidskriftsartikel (refereegranskat)abstract
- An extensive investigation of carrier mobility is presented for thin-film transistors (TFTs) with single-walled carbon nanotube (SWCNT) networks as the semiconductor channel. For TFTs particularly with low-density SWCNTs in the networks, the extracted mobility using the standard method for Si metal-oxide-semiconductor field-effect transistors is erroneous, mainly resulting from use of a parallel-plate capacitor model and assumption of the source-drain current being inversely proportional to the channel length. Large hysteresis in the transfer characteristics further complicates the extraction. By properly addressing all these challenges in this letter, a comprehensive methodology is established, leading to the extraction of mobility values that are independent of geometrical parameters.
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| 8. |
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| 9. |
- Yang, Xu-Fang, et al.
(författare)
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High efficient isolation and systematic identification of human adipose-derived mesenchymal stem cells
- 2011
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Ingår i: Journal of Biomedical Science. - : Springer Science and Business Media LLC. - 1021-7770 .- 1423-0127. ; 18, s. 59-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Developing efficient methods to isolate and identify human adipose-derived mesenchymal stem cells (hADSCs) remains to be one of the major challenges in tissue engineering. Methods: We demonstrate here a method by isolating hADSCs from abdominal subcutaneous adipose tissue harvested during caesarian section. The hADSCs were isolated from human adipose tissue by collagenase digestion and adherence to flasks. Results: The yield reached around 1 x 10(6) hADSCs per gram adipose tissue. The following comprehensive identification and characterization illustrated pronounced features of mesenchymal stem cells (MSCs). The fibroblast-like hADSCs exhibited typical ultrastructure details for vigorous cell activities. Karyotype mapping showed normal human chromosome. With unique immunophenotypes they were positive for CD29, CD44, CD73, CD105 and CD166, but negative for CD31, CD34, CD45 and HLA-DR. The growth curve and cell cycle analysis revealed high capability for self-renewal and proliferation. Moreover, these cells could be functionally induced into adipocytes, osteoblasts, and endothelial cells in the presence of appropriate conditioned media. Conclusion: The data presented here suggest that we have developed high efficient isolation and cultivation methods with a systematic strategy for identification and characterization of hADSCs. These techniques will be able to provide safe and stable seeding cells for research and clinical application.
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| 10. |
- Zhang, Hong-Zhen, et al.
(författare)
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PINCH Protein Expression in Normal Endometrium, Atypical Endometrial Hyperplasia and Endometrioid Endometrial Carcinoma
- 2010
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Ingår i: CHEMOTHERAPY. - : S. Karger AG. - 0009-3157 .- 1421-9794. ; 56:4, s. 291-297
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Tidskriftsartikel (refereegranskat)abstract
- Background: Particularly interesting new cysteine-histidine rich protein ( PINCH), as an adapter protein of the LIM family for signal transduction in the integrin and growth factor pathway, is upregulated in the stroma of several common types of cancers and involved in promoting tumor progression. In the present study, we examined PINCH expression in normal endometrium, atypical endometrial hyperplasia and endometrioid carcinoma, and further studied the relationships of PINCH expression with clinicopathological variables in cancer patients. Methods: PINCH expression was examined by immunohistochemistry in 23 normal endometrial samples, 18 atypical endometrial hyperplasias and 48 endometrioid endometrial carcinomas. Results: The PINCH expression in the stroma of cancer (71%) was significantly increased compared to either normal endometrium (17%, p andlt; 0.0001) or atypical hyperplasia (39%, p = 0.017), along with 9 cancers that had stronger PINCH expressions at the invasive margin of the cancers compared to the inner cancers. PINCH expression in cancer was higher in the patients with hypertension (p = 0.041) and estrogen exposure time andgt;30 years (p = 0.021). On the other hand, PINCH expression was not related to menopausal status, gravid status, blood sugar/lipid, family background of cancer, histological grade, myometrial invasion, cervical involvement, lymph nodal metastases, growth pattern, estrogen and progestogen receptors (p andgt; 0.05). Conclusion: The results suggest that PINCH seems to play a role, presently unknown, in the tumorigenesis and development of endometrial cancer that merits further study.
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| 11. |
- Gong, Karin Anne Xia, 1965, et al.
(författare)
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Wear Evaluation on Ni3Al/MnS Composite Related to Metallurgical Processes
- 2012
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Ingår i: Journal of Iron and Steel Research International. - 1006-706X. ; 19:7, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Iron alloyed Ni3Al with composition of Ni-18. 8A1-10. 7Fe0. 5Mn-0. 5Ti-0.2B in atom percent (NAC alloy)showed attractive tribological properties under unlubrication condition at room temperature. The alloy was preparedby hot isostatic pressing (HIP) process. The wear properties were associated with its intrinsic deformation mechanism.Unfortunately, the single phase NAC-alloy worked inadequately with its counterpart disk, and also showed apoor machinability. In the present work, NAC-alloy matrix composite with 6% (volume percent) MnS (manganese sulfide)particle addition was studied to improve its wear behaviors and performance on machining. Two metallurgical processes of HIP and vacuum casting were applied to produce the testing materials. Pin-on-disk (POD) measurements were carried outat room temperature. A commercial vermicular graphite cast iron was selected as a reference material. The counterpartdisk was made of a grey cast iron as liner material in ship engines. The contact pressures of 2. 83 MPa and 5. 66 MPawere normally applied in the tests. The investigation indicated that MnS particle addition in the NAC-alloy compositesfunctions as an effective solid lubricant, and improved wear properties and machinability of the materials. Obviously,as-cast NAC-alloy with in-situ formed MnS phase was working more effectively with the counterpart, comparingto the HIPed NAC-alloy composite with MnS particles. At the high contact pressure of 5.66 MPa, the specificwear rate of the as-cast NAC-alloy composite was high. The phenomenon of the negative effect is mostly due to thebrittle second NiAl phase as evidenced in the microstructure analysis.
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| 12. |
- Gui, Chuan-Zhi, et al.
(författare)
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Changes of learning and memory ability and brain nicotinic receptors of rat offspring with coal burning fluorosis
- 2010
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Ingår i: Neurotoxicology and Teratology. - : Elsevier BV. - 0892-0362 .- 1872-9738. ; 32:5, s. 536-541
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the investigation is to reveal the mechanism of the decreased ability of learning and memory induced by coal burning fluorosis. Ten offspring SD rats aged 30 days, who were born from the mothers with chronic coal burning fluorosis, and ten offspring with same age from the normal mothers as controls were selected. Spatial learning and memory of the rats were evaluated by Morris Water Maze test. Cholinesterase activity was detected by photometric method. The expressions of nicotinic acetylcholine receptors (nAChRs) at protein and mRNA levels were detected by Western blotting and Real-time PCR, respectively. The results showed that in the rat offspring exposed to higher fluoride as compared to controls, the learning and memory ability declined; the cholinesterase activities in the brains were inhibited; the protein levels of alpha 3, alpha 4 and alpha 7 nAChR subunits were decreased which showed certain significant correlations with the declined learning and memory ability: and the mRNA levels of alpha 3 and alpha 4 nAChRs were decreased, whereas the alpha 7 mRNA increased. The data indicated that coal burning fluorosis can induce the decreased ability of learning and memory of rat offspring, in which the mechanism might be connected to the changed nAChRs and cholinesterase.
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| 13. |
- Li, Zhi-Hua, et al.
(författare)
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Biochemical and physiological responses in liver and muscle of rainbow trout after long-term exposure to propiconazole
- 2010
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier Inc. - 0147-6513 .- 1090-2414. ; 73:6, s. 1391-1396
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the chronic toxic effects of PCZ, a triazole fungicide commonly present in surface and ground water, on morphological indices, ROS generation and RNA/DNA ratio in liver and white muscle of rainbow trout were investigated. Fish were exposed at sublethal concentrations of PCZ (0.2, 50 and 500mugL(-1)) for 7, 20 and 30d. Compared with the control, there were significant lower CF and HSI in fish exposed at the highest concentration of PCZ. ROS levels in both tissues increased significantly at higher PCZ concentrations (50 and 500mugL(-1)) after 20d and above, as well as in muscle of fish exposed at lowest PCZ concentration (0.2mugL(-1)) after 30d. The hepatic antioxidant enzymes (SOD and CAT) activities were induced significantly at higher concentrations (50, 500mugL(-1)) of PCZ after 20d and at 50mugL(-1) after 30d. Additional, hepatic SOD activity was significantly induced at 0.2mugL(-1) after 30d. Compared with the hepatic antioxidant enzymes activities in fish exposed to 50mugL(-1) of PCZ, there was a decreasing trend in those exposed to 500mugL(-1) after 30d exposure. However, both the antioxidant enzymes activities were significantly inhibited in muscle of fish exposed to 500mugL(-1) PCZ after 30d. Moreover there was significant lower RNA/DNA ratio in both tissues after long-term exposure to higher concentration of PCZ. In short, environmental concentrations of PCZ could not induce obvious impacts on fish, but long-term exposure to higher concentrations of CBZ could affect seriously the health status of fish.
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| 14. |
- Li, Zhi-Hua, et al.
(författare)
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Effects of exposure to sublethal propiconazole on intestine-related biochemical responses in rainbow trout, Oncorhynchus mykiss
- 2010
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Ingår i: Chemico-Biological Interactions. - : Elsevier BV. - 0009-2797 .- 1872-7786. ; 185:3, s. 241-246
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Tidskriftsartikel (refereegranskat)abstract
- The effect of long-term (30 days) exposure to PCZ (0.2, 50, and 500 microg l(-1)) on intestine-related biochemical markers in rainbow trout was investigated. Multiple biomarkers were measured, including digestive enzymes (proteolytic enzymes and amylase), antioxidant responses (TBARS, CP, SOD, CAT, GR and GPx) and energy metabolic parameters (RNA/DNA ratio, Na(+)-K(+)-ATPase). Exposure to 500 microg l(-1) PCZ led to significantly inhibited (p<0.01) proteolytic enzyme and amylase activity. Activities of the antioxidant enzymes SOD, CAT, and GPx gradually increased at lower PCZ concentrations (0.2 and 50 microg l(-1)). At the highest concentration (500 microg l(-1)), oxidative stress was apparent as significant higher (p<0.05) lipid peroxidation and protein carbonyls, associated with an inhibition of antioxidant enzymes activity. Moreover, energy metabolic parameters (RNA/DNA ratio, Na(+)-K(+)-ATPase) were significantly inhibited (p<0.01) in the intestines of fish exposed to 500 microg l(-1) PCZ, compared with controls. We suggest that long-term exposure to PCZ could result in several responses in intestine-related biochemical markers, which potentially could be used as indicators for monitoring residual PCZ present in the aquatic environment.
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| 15. |
- Li, Zhi-Hua, et al.
(författare)
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Effects of exposure to sublethal propiconazole on the antioxidant defense system and Na+-K+-ATPase activity in brain of rainbow trout, Oncorhynchus mykiss
- 2010
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Ingår i: Aquatic Toxicology. - : Elsevier. - 0166-445X .- 1879-1514. ; 98:3, s. 297-303
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Tidskriftsartikel (refereegranskat)abstract
- Propiconazole (PCZ), a triazole fungicide, is widely present in the aquatic environment, but little is known regarding its chronic toxicity in the fish brain. This study assessed the effects of long-term exposure to PCZ on the antioxidant defense system and Na(+)-K(+)-ATPase activity of rainbow trout brain. Fish were exposed to sublethal concentrations of PCZ (0.2, 50, and 500 microg/l) for 7, 20, and 30 days, respectively. Oxidative stress indices (reactive oxygen species, lipid peroxidation, and carbonyl protein) and antioxidant parameters (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and reduced glutathione) were measured, as well as Na(+)-K(+)-ATPase activity. Adaptive responses to PCZ-induced stress were observed at 7 days. With prolonged exposure, significantly higher levels of oxidative indices were indicative of oxidative stress, as also were the significant inhibition of antioxidant enzyme activity and reduced glutathione content. Na(+)-K(+)-ATPase activity was significantly inhibited after prolonged exposure. Chemometrics of all parameters by principal component analysis, enabled the separation of sampled individuals into four groups with 93.39% of total accumulated variance. A low level of oxidative stress can induce the adaptive responses of the antioxidant defense system, while prolonged exposure to PCZ may lead to serious oxidative damage in fish brain. We suggest that selected biochemical markers in fish brain could be used as potential biomarkers for monitoring residual fungicides present in the aquatic environments.
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| 16. |
- Li, Zhi-Hua, et al.
(författare)
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Modulation of glutathione-related antioxidant defense system of fish chronically treated by the fungicide propiconazole
- 2010
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Ingår i: Comparative Biochemistry and Physiology - Part C. - : Elsevier. - 1532-0456 .- 1878-1659. ; 152:3, s. 392-398
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Tidskriftsartikel (refereegranskat)abstract
- Recently, residual fungicides are generally recognized as relevant sources of aquatic environmental pollutants. However, the toxicological effects of these contaminants have not been adequately researched. In this study, the chronic effect of PCZ, a triazole-containing fungicide commonly present in aquatic environment, on GSH-related antioxidant system and oxidative stress indices of rainbow trout (Oncorhynchus mykiss) were investigated. Fish were exposed at sub-lethal concentrations of PCZ (0.2, 50 and 500 microg/L) for 7, 20 and 30 days. GSH levels and GSH-related enzyme activities, including GPx, GR and GST, were quantified in three tissues-liver, gill and muscle. The levels of LPO and CP were also measured as makers of oxidative damage. In addition, the correlations of the measured parameters in various tissues were evaluated by using PCA. The results of this study indicate that chronic exposure of PCZ has resulted in different responses in various tissues and the gill was the most sensitive tissue; however, before these parameters are used as potential biomarkers for monitoring residual fungicides in aquatic environment, more detailed experiments in laboratory need to be performed in the future.
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| 17. |
- Liu, Zhiying, et al.
(författare)
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SMALL-Hysteresis Thin-Film Transistors Achieved by Facile Dip-Coating of Nanotube/Polymer Composite
- 2012
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Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 24:27, s. 3633-3638
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Tidskriftsartikel (refereegranskat)abstract
- Small-hysteresis, high-performance thin-film transistors (TFTs) are readily realized simply by dip-coating of a solution-processable composite. The composite consists of single-walled carbon nanotubes (SWCNTs) embedded in semiconducting polymer used as the channel material. The resultant TFTs simultaneously exhibit large on/off current ratio, high on-current level, high mobility in the range 10−20 cm2V−1s−1, and good uniformity and scalability.
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| 18. |
- Liu, Zhiying, et al.
(författare)
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Solution-Processable Nanotube/Polymer Composite for High-Performance TFTs
- 2011
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 32:9, s. 1299-1301
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Tidskriftsartikel (refereegranskat)abstract
- Thin-film field-effect transistors (TFTs) are readily fabricated using a semiconductor composite that is solution processed under ambient conditions for the conduction channel. The composite comprises single-walled carbon nanotubes (SWCNTs) embedded in poly-9,9' dioctyl-fluorene-co-bithiophene. Carrier mobility values approaching 10 cm(2)V(-1)s(-1) are obtained for the composite with relatively high SWCNT concentrations. When the SWCNT concentration is reduced for a large ON/OFF current ratio > 10(6), the mobility remains decent around 0.3 cm(2)V(-1)s(-1). The resultant TFTs display remarkable environmental and operational reliability. Nanotube-based composites are therefore of significance in printed electronics owing to their simplicity in device fabrication and competitiveness in device performance.
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| 19. |
- Lopez Cabezas, Ana, 1980-, et al.
(författare)
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Influence of Carbon Nanotubes on Thermal Stability of Water-Dispersible Nanofibrillar Polyaniline/Nanotube Composite
- 2012
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Ingår i: Materials. - Basel, Switzerland : MDPI AG. - 1996-1944. ; 5:2, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- Significant influence on the thermal stability of polyaniline (PANI) in the presence of multi-walled carbon nanotubes (MWCNTs) is reported. By means of in-situ rapid mixing approach, water-dispersible nanofibrillar PANI and composites, consisting of MWCNTs uniformly coated with PANI in the state of emeraldine salt, with a well-defined core-shell heterogeneous structure, were prepared. The de-protonation process in PANI occurs at a lower temperature under the presence of MWCNTs on the polyaniline composite upon thermal treatment. However, it is found that the presence of MWCNTs significantly enhances the thermal stability of PANI's backbone upon exposure to laser irradiation, which can be ascribed to the core-shell heterogeneous structure of the composite of MWCNTs and PANI, and the high thermal conductivity of MWCNTs.
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| 20. |
- Lopez Cabezas, Ana, et al.
(författare)
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Morphological development of nanofibrillar composites of polyaniline and carbon nanotubes
- 2010
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Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 160:7-8, s. 664-668
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Tidskriftsartikel (refereegranskat)abstract
- Nanofibrillar composite of polyaniline (PANI)/multi-walled carbon nanotubes (MWNTs) is readily synthesized by means of conventional in situ polymerization process. It is found that the MWNT loading during polymerization has a significant influence on both the micro- and macro-scale morphological properties of the composites. At low MWNT loadings, PANI/MWNTs are formed as individual nanofibers, similar to that of the neat PANI in the absence of MWNTs. With the increase in MWNT loading, the composite exhibits granular form and becomes a continuous porous matrix at higher MWNT loadings. A possible mechanism is proposed to account for the structural variation of the composites caused by MWNTs at the different loadings.
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| 21. |
- Lopez Cabezas, Ana, 1980-
(författare)
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Nanofibrillar Materials for Organic and Printable Electronics
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, organic electronics have attracted great attention due to their multiple advantages such as light weight, flexibility, large area fabrication and cost-effective production processes. The recent progress in fabricating organic electronic devices has been achieved with the development of new materials which provide competing functionalities to the electronics devices. However, as it happens with all type of technologies, organic electronics is not free from challenges. In the latest OE-A Roadmap for organic and printed electronics (2011), the “red brick walls” were identified, and the following three main challenges were pointed out as the potential roadblocks from the material point of view: electrical performance, solution processability (especially formulations in non-toxic solvents) and environmental stability. Currently there is a significant increasing interest in optimizing or developing novel materials to meet those requirements. This thesis presents processing development and study of nanofibrillar materials and deals with the optimization for its applicability for organic electronics. The overall work presented in the thesis is based on three nanofibrillar materials: Polyaniline (PANI), carbon nanotubes (CNTs) and the CNT/PANI composite. First, the solution processability of carbon nanotubes and polyaniline is studied respectively, and through covalent and non-covalent methods, stable aqueous dispersions of these materials are successfully achieved. Second, a composite consisting of multi-walled carbon nanotubes (MWCNTs) and PANI with a core-shell structure is developed and characterized. The investigation of the effects of the loading and type of nanotubes incorporated in the composite material, led to understanding on the fundamental theory underlying the composite morphology. Based on those findings and by carefully optimizing the synthesis procedure, water dispersible MWCNT/PANI nanofibrillar composite is successfully synthesized becoming compatible with solution processable techniques, such as spray coating and potentially with printing technology. With the incorporation of carbon nanotubes, the nanofibrillar composite reaches conductivities 20 times higher than that of the pure polymer. Moreover, the presence of the nanotubes in the composite material decelerates up to 60 times the thermal ageing of its conductivity, making the polymer more robust and suitable for possible manufacturing processes. Furthermore, the composite material still retains the advantageous properties of PANI: electrochromism, tunable conductivities, and sensing capabilities. Third, the stable dispersions of PANI, CNTs and MWCNT/PANI composite were effectively deposited by spray coating technique on several low-cost substrates (PET, PEN, polyimide and papers), and homogeneous, flexible, large-area films were fabricated. Additionally, by spraying the materials on pre-fabricated inkjet printed electrodes, a pH sensor based on the MWCNT/PANI composite and a humidity sensor based on functionalized MWCNTs capable of working at GHz range were demonstrated, which shows that the nanofibrillar materials studied in this thesis work are promising sensor materials for wireless application at ultra-high frequency (UHF) band. Finally, the humidity sensor was integrated into a sensor-box demonstrating a hybrid interconnection platform where printed electronics can be seamlessly integrated with silicon-based electronics. The integration closes the gap between the two technologies, anticipating the adaption of organic electronic technologies.
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| 22. |
- Luo, Jun, et al.
(författare)
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Effects of carbon pre-silicidation implant into Si substrate on NiSi
- 2014
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 120, s. 178-181
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effects of carbon pre-silicidation implant into Si(1 0 0) substrate on NiSi were investigated. NiSi films with carbon pre-silicidation implant to different doses were characterized by means of sheet resistance measurements, X-ray diffraction, scanning electron microscopy (SEM), planar view transmission electron microscopy (TEM) and second ion mass spectroscopy (SIMS). The presence of C is found to indeed significantly improve the thermal stability of NiSi as well as tends to change the preferred orientations of polycrystalline NiSi. The homogeneously distributed C at NiSi grain boundaries and C peak at NiSi/Si interface is ascribed to the improved thermal stability of NiSi. More importantly, the dose of carbon pre-silicidation implant also plays a key role in the formation of NiSi, which is suggested not to exceed a critical value about 5 x 10(15) cm(-2) in practical application in accordance with the results achieved in this work. (C) 2013 Elsevier B.V. All rights reserved.
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| 23. |
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| 24. |
- Luo, Jun, et al.
(författare)
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Thermal Stability and Dopant Segregation for Schottky Diodes With Ultrathin Epitaxial NiSi(2-y)
- 2011
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 32:8, s. 1029-1031
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Tidskriftsartikel (refereegranskat)abstract
- The Schottky barrier height (SBH) of an ultrathin epitaxial NiSi(2-y) film grown on Si(100) is modified significantly by means of dopant segregation (DS). The DS process begins with the NiSi(2-y) formation and is followed by dopant implantation and drive-in annealing. The rapid lattice restoration and superior morphological stability upon heat treatment up to 800 degrees C allow the epitaxial NiSi(2-y) film to take full advantage of the DS process. For drive-in annealing below 750 degrees C, the effective SBH is altered to similar to 0.9-1 eV for both electrons and holes by B-DS and As-DS, respectively, without deteriorating the integrity of the NiSi(2-y) film.
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| 25. |
- Luo, Jun, et al.
(författare)
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Variation of Schottky barrier height induced by dopant segregation monitored by contact resistivity measurements
- 2014
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 120, s. 174-177
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Tidskriftsartikel (refereegranskat)abstract
- Change of contact resistivity (rho(c)) is monitored for evaluation of Schottky barrier height (SBH) variation induced by dopant segregation (DS). This method is particularly advantageous for metal-semiconductor contacts of small SBH, as it neither requires low-temperature measurement needed in current-voltage characterization of Schottky diodes nor is affected by reverse leakage current often troubling capacitance-voltage characterization. With PtSi contact to both n- and p-type diffusion regions, and the use of opposite or alike dopants implant into pre-formed PtSi films followed by drive-in anneal at different temperatures to induce DS at PtSi/Si interface, the formation of interfacial dipole is confirmed as the responsible cause for modification of effective SBHs thus the increase or decrease of rho(c). A tentative explanation for the change of contact resistivity based on interfacial dipole theory is provided in this work. Influences and interplay of interfacial dipole and space charge on effective SBH are also discussed. (C) 2013 Elsevier B.V. All rights reserved.
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