| 21. |
- Tångring, I., et al.
(författare)
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Strong 1.3-1.6 mu m light emission from metamorphic InGaAs quantum wells on GaAs
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:17, s. 171902-
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate strong 1.3-1.6 mu m photoluminescence (PL) from InGaAs quantum wells (QWs) grown on alloy graded InGaAs buffer layers on GaAs by molecular beam epitaxy. The epistructures show quite smooth surfaces with an average surface roughness less than 2 nm. The PL intensity is comparable with those from InAs quantum dots and InGaAs QWs on GaAs, and InGaAsP QWs on InP at similar wavelengths, but stronger than those from GaInNAs QWs (at least 10 times higher at around 1.5-1.6 mu m). The excellent optical quality implies that the metamorphic approach could be a promising alternative to GaInNAs(Sb) QWs for 1.55 mu m lasers on GaAs.
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| 22. |
- Wang, Ming-Wei, et al.
(författare)
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Expression of PINCH protein in gliomas and its clinicopathological significance
- 2007
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Ingår i: Oncology. - : S. Karger AG. - 0890-9091 .- 0030-2414 .- 1423-0232. ; 72:5-6, s. 343-346
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Particularly interesting new cysteine-histidine-rich protein (PINCH), as a LIM domain adapter protein, functions in the integrin and growth factor signal transduction pathway, and is upregulated in tumor-associated stroma in several types of cancers. However, no study of PINCH has been carried out in gliomas, therefore we examined PINCH expression in gliomas and its clinicopathological significance. Methods: PINCH expression was immunohistochemically examined in 82 gliomas, along with 26 matched adjacent normal brain samples and 10 recurred gliomas. Results: PINCH was strongly expressed in the primary (35%, p = 0.0001) or recurred tumors (40%, p = 0.004) and weak in normal brain tissue. PINCH expression was significantly increased in high-grade gliomas (55 vs. 24%, high- vs. low-grade gliomas, p = 0.004). There was no association of PINCH expression with gender, age, tumor number, size, histological type and tumor location (p > 0.05). Conclusions: PINCH expression may be involved in glioma development and differentiation. Copyright © 2008 S. Karger AG.
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| 23. |
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| 24. |
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| 25. |
- Wang, Shu Min, 1963, et al.
(författare)
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High Performance 1.3 μm GaInNAs Quantum Well Lasers on GaAs
- 2008
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819470843 ; 6909, s. 690905-
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Konferensbidrag (refereegranskat)abstract
- We present state-of-the-art performance of 1.3 μm GaInNAs lasers on GaAs grown by molecular beam epitaxy. The lowest achieved threshold current density is 297, 150 and 133 A/cm 2 per quantum well (QW) for single, double and triple QW broad area lasers with a cavity length of 1 mm. The characteristic temperature is 93-133 K in the ambient temperature range of 10-80 °C for broad area lasers depending on the cavity length, and increases to 163-208 K for ridge waveguide lasers as a result of temperature insensitive lateral carrier diffusion in QWs. The maximum 3 dB bandwidth of 17 GHz is achieved in a double QW laser. Uncooled 10 Gb/s operation up to 110 °C has been demonstrated.
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| 26. |
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| 27. |
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| 28. |
- Zhang, Zhiyong, 1970-, et al.
(författare)
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Expression of MAC30 in rectal cancers with or without preoperative radiotherapy
- 2007
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Ingår i: Oncology. - : S. Karger AG. - 0890-9091 .- 0030-2414 .- 1423-0232. ; 71:3-4, s. 259-265
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Meningioma-associated protein (MAC30) is overexpressed in several types of cancers, but its therapeutic implication in the patients has not been studied. We examined the relationship of MAC30 with clinicopathological and biological factors in rectal cancer patients with or without radiotherapy (RT). Methods: MAC30 was immunohistochemically examined in 75 distant and 91 adjacent normal mucosa specimens, 132 primary tumours and 39 lymph node metastases from rectal cancer patients participating in a clinical trial of preoperative RT. Results: In the RT group, MAC30 was or tended to be positively correlated with infiltrated growth pattern (p = 0.02), PRL (phosphatase of regenerating liver, p = 0.01) and Ki-67 expression (p = 0.06). MAC30 at the invasive margin of the metastasis was related to poor survival (p = 0.02) in the whole group of patients. MAC30 in primary tumours was not related to recurrence and survival in the non-RT or RT group. Conclusions:MAC30 expression in metastasis was an indicator for poor survival. After RT, MAC30 seemed to be more related to aggressive morphological and biological factors, however, we did not find direct evidence that MAC30 expression was related to the outcome of patients with or without RT. Copyright © 2006 S. Karger AG.
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| 29. |
- Zhang, Zhi-Yong, et al.
(författare)
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Nup88 expression in normal mucosa, adenoma, primary adenocarcinoma and lymph node metastasis in the colorectum
- 2007
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Ingår i: Tumor Biology. - : Springer Science and Business Media LLC. - 1010-4283 .- 1423-0380. ; 28:2, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: It was the aim of this study to investigate Nup88 expression in normal colorectal mucosa, adenoma, adenocarcinoma and lymph node metastasis, as well as the relationship between Nup88 expression and clinicopathological features. Methods: Nup88 expression was examined by immunohistochemistry in 84 normal mucosa samples, 32 adenomas, 181 primary adenocarcinomas, and 18 lymph node metastases from colorectal tumour patients. Results: Nup88 expression was observed in normal epithelial and tumour cells. The frequency of strong Nup88 expression was increased from normal mucosa or adenoma to primary tumour and lymph node metastasis (p < 0.0001). There was no significant difference in the expression between normal mucosa and adenoma (p = 0.41). The frequency of strong Nup88 expression was higher in ulcerated tumours (40%) than in polypoid/large fungating tumours (23%, p = 0.048). The frequency of strong Nup88 expression was significantly different among tumours with good (21%), moderate (42%) and poor differentiation (48%, p = 0.01). Nup88 expression was not related to the patients' gender, age, tumour location, size, histological type, invasive depth, lymph node status and Dukes stage (p > 0.05). Conclusion: Our results suggest that Nup88 may play a role during the development, aggressiveness and differentiation of colorectal tumours. Copyright © 2007 S. Karger AG.
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| 30. |
- Zhao, Ming, 1975-
(författare)
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Growth and Characterization of Strain-engineered Si/SiGe Heterostructures Prepared by Molecular Beam Epitaxy
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The strain introduced by lattice mismatch is a built-in characteristic in Si/SiGe heterostructures, which has significant influences on various material properties. Proper design and precise control of strain within Si/SiGe heterostructures, i.e. the so-called “strain engineering”, have become a very important way not only for substantial performance enhancement of conventional microelectronic devices, but also to allow novel device concepts to be integrated with Si chips for new functions, e.g. Si-based optoelectronics. This thesis thus describes studies on two subjects of such strain-engineered Si/SiGe heterostructures grown by molecular beam epitaxy (MBE). The first one focuses on the growth and characterizations of delicately strain-symmetrized Si/SiGe multi-quantum-well/superlattice structures on fully relaxed SiGe virtual substrates for light emission in the THz frequency range. The second one investigates the strain relaxation mechanism of thin SiGe layers during MBE growth and post-growth processes in non-conventional conditions.Two types of THz emitters, based on different quantum cascade (QC) intersubband transition schemes, were studied. The QC emitters using the diagonal transition between two adjacent wells were grown with Si/Si0.7Ge0.3 superlattices up to 100 periods. It was shown that nearly perfect strain symmetry in the superlattice with a high material quality was obtained. The layer parameters were precisely controlled with deviations of ≤ 2 Å in layer thickness and ≤ 1.5 at. % in Ge composition from the designed values. The fabricated emitter devices exhibited a dominating emission peak at ~13 meV (~3 THz), which was consistent with the design. An attempt to produce the first QC THz emitter based on the bound-to-continuum transition was made. The structures with a complicated design of 20 periods of active units were extremely challenging for the growth. Each unit contained 16 Si/Si0.724Ge0.276 superlattice layers, in which the thinnest one was only 8 Å. The growth parameters were carefully studied, and several samples with different boron δ-doping concentrations were grown at optimized conditions. Extensive material characterizations revealed a high crystalline quality of the grown structures with an excellent growth control, while the heavy δ-doping may introduce layer undulations as a result of the non-uniformity in the strain field. Moreover, carrier lifetime dynamics, which is crucial for the THz QC structure design, was also investigated. Strain-symmetrized Si/SiGe multi-quantum-well structures, designed for probing the carrier lifetime of intersubband transitions inside a well between heavy hole 1 (HH1) and light hole 1 (LH1) states with transition energies below the optical phonon energy, were grown on SiGe virtual substrates. The lifetime of the LH1 excited state was determined directly with pump-probe spectroscopy. The measurements indicated an increase of lifetime by a factor of ~2 due to the increasingly unconfined LH1 state, which agreed very well with the theory. It also showed a very long lifetime of several hundred picoseconds for the holes excited out of the well to transit back to the well through a diagonal process.Strained SiGe grown on Si (110) substrates has promising potentials for high-speed microelectronics devices due to the enhanced carrier mobility. Strain relaxation of SiGe/Si(110) subjected to different annealing treatments was studied by X-ray reciprocal space mapping. The in-plane lattice mismatch was found to be asymmetric with the major strain relaxation observed in the lateral [001] direction. It was concluded that this was associated to the formation and propagation of conventional a/2<110> dislocations oriented along [110]. This was different from the relaxation observed during growth, which was mainly along in-plane [110].A novel MBE growth process to fabricate thin strain-relaxed Si0.6Ge0.4 virtual substrates involving low-temperature (LT) buffer layers was investigated. At a certain LT-buffer growth temperature, a dramatic increase in the strain relaxation accompanied with a decrease of surface roughness was observed in the top SiGe, together with a cross-hatch/cross-hatch-free transition in the surface morphology. It was explained by the association with a certain onset stage of the ordered/disordered transition during the growth of the LT-SiGe buffer.
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