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- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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Gas sensor arrays for combustion control
- 2005
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Ingår i: Encyclopedia of Sensors, eds.. - California : American Scientific Publishers. - 158883056X ; , s. 139-154
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The applications of sensors range from medical diagnostics to industrial manufacturing and to defense and national security applications. When an area spans such a large diversity of research, and where research from many different countries is also involved, a review of these developments becomes especially useful. Because it bridges science and technology the field also provides a desired interaction between researchers and research in technologically advanced and developing countries. The present series of volumes, "The Encyclopedia of Sensors" , the first of its kind, is intended to provide a timely compendium of the entire field. As such it can be expected to play a significant role in worldwide future progress and understanding."
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| 5. |
- Lloyd-Spets, Anita, 1951-, et al.
(författare)
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MISiC-FET NH3 sensors for SCR control in exhaust and flue gases
- 2005
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Ingår i: Encyclopedia of Sensors, eds.. - California : American Scientific Publishers. - 158883056X ; , s. 205-218
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The applications of sensors range from medical diagnostics to industrial manufacturing and to defense and national security applications. When an area spans such a large diversity of research, and where research from many different countries is also involved, a review of these developments becomes especially useful. Because it bridges science and technology the field also provides a desired interaction between researchers and research in technologically advanced and developing countries. The present series of volumes, "The Encyclopedia of Sensors" , the first of its kind, is intended to provide a timely compendium of the entire field. As such it can be expected to play a significant role in worldwide future progress and understanding."
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- Lloyd-Spets, Anita, et al.
(författare)
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MISiCFET chemical gas sensors for high temperature and corrosive environment applications
- 2002
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 389-3, s. 1415-1418
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Tidskriftsartikel (refereegranskat)abstract
- A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The buried gate design allows the sensor to operate at high temperatures, routinely up to 600degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.
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- Lloyd-Spets, Anita, et al.
(författare)
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New materials for chemical and biosensors
- 2006
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Ingår i: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 21:3, s. 253-256
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Tidskriftsartikel (refereegranskat)abstract
- Wide band gap materials such as SiC, AlN, GaN, ZnO, and diamond have excellent properties such as high operation temperature when used as field effect devices and a high resonating frequency of the substrate materials used in piezoelectric resonator devices. Integration of FET and resonating sensors on the same chip enables powerful miniaturized devices, which can deliver increased information about a gas mixture or complex liquid. Examples of sensor devices based on different wide band gap materials will be given.
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- Nakagomi, Shinji, et al.
(författare)
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Influence of gate bias of MISiC-FET gas sensor device on the sensing properties
- 2005
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 108, s. 501-507
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Tidskriftsartikel (refereegranskat)abstract
- The influence of gate bias on the gas sensing properties of SiC-based field effect transistors with catalytic gate and a buried short channel has been studied. The drain current-voltage (I-d-V-D) characteristics of the device reveal non-saturation property, which is a consequence of the short channel design. The drain current is larger in hydrogen ambient than in oxygen ambient at the same drain voltage. The threshold voltage decreases with increasing positive gate bias, and increases with increasing negative gate bias. When a positive bias is applied to the gate, the I-d-V-D characteristics reveal a tendency to saturate. A positive gate bias increases the drain voltage response to hydrogen, as compared with a negative applied gate bias. However, a positive gate bias decreases the stability of the device signal. A change in the channel resistivity is the main reason for the change in the electrical properties when a positive gate bias is applied. A physical model that explains the influence of the gate bias has been studied, and the behavior of the barrier height in the channel was estimated by using the temperature dependence of the I-d-V-D characteristics.
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- Nakagomi, S, et al.
(författare)
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Substrate bias amplification of a SiC junction field effect transistor with a catalytic gate electrode
- 2004
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 457-460, s. 1507-1510
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Tidskriftsartikel (refereegranskat)abstract
- The drain current-voltage (I-d-V-D) characteristics of a chemical gas sensor based on a catalytic metal insulator silicon carbide field effect transistor (SiC-FET) were measured in H-2 or O-2 ambient while applying negative substrate bias, V-sub, at temperatures up to 600degreesC. An increase in the negative V-sub gives rise to an increase of the drain voltage at a given drain current level, which can be used to adjust the device baseline. In addition, we found that the difference in drain voltage between H-2 and O-2 ambient at a given drain current level (the gas response to H-2) increases for an increased negative substrate bias. By modifying an equation for the drain current in a SIT (static induction transistor), the influence of substrate bias on the amplification factors, mu and eta, was estimated using the temperature dependence of the I-d-V-D characteristics. From this, the effect of substrate bias on the gas response to hydrogen was calculated. It was clarified that the increase in the gas response caused by the negative substrate bias is due to a substrate bias dependence of the amplification factor of the short channel device.
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| 10. |
- Spets, Helena
(författare)
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Regulation of apoptosis in human multiple myeloma
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Multiple myeloma (MM) is a clonal expansion of malignant plasmablasts-plasma cells in the bone marrow. MM is slowly proliferating and an increased resistance to apoptosis may be crucial for the tumor progression. By the use of MM cell lines and primary cells the role of some growth factors, and genes regulating survival or apoptosis in human MM cell lines and primary cells, was investigated. The in vitro requirements for growth and survival of MM cells are heterogenous. This has hampered studies of molecular mechanisms underlying the effects of interleukin-6 (IL-6). The results of this thesis showthat IL-6, in the presence of serum, can convey survival dissociated from the effects of IL-6 on proliferation in two pairs of MM cell lines, U-266-1970/U-266-1984 and HL407E/HL407L. In the absence of serum IL-6 may also augment apoptosis. The findings therefore provide a useful human model system of IL-6 dependent and independent cell lines to study the molecular mechanisms underlying IL-6 effects in MM.The thesis also report on the expression of seven Bcl-2 related proteins; Bcl-2, Mcl-1, Bcl-x, Bcl-w, Bax, Bak, and Bad in MM cell lines and normal plasma cells. Elevated expression levels of Bcl-2 and Mel-1, as well as decreased levels of Bax expression were demonstrated in MM cells, and may therefore be associated with the malignant phenotype. Downregulation of the expression of Bcl-2, Mcl-1, and Bcl-x, and an upregulated Bax expression were recorded as a result of IL-6 deprivation in two IL-6 dependent-MM cell lines.A poor response to Fas and dexamethasone induced apoptosis is evident in some MM cell lines and primary cells. We here report that sensitivity to Fas mediated apoptosis can be augmented by IFN-γ or IFN-α in the U-266-1970, U-266-1984, and U-1958 cell lines. The mechanism by which IFNs regulate the sensitivity to apoptosis is unknown. IFNs increased the Fas antigen expression in one of three cell lines, but did not alter the expression of Bcl-2, or Bax, and was shown to be independent of growth inhibition.We also present results showing that IGF-IR signaling can mediate resistance to anti-Fas and dexamethasone induced apoptosis in two IGF-I responsive MM cell lines, LP-1 and Karpas 707. The results show that IGF-IR signaling may be a potent inhibitor of apoptosis, but does not counteract the growth inhibitory effect of dexamethasone in MM cell lines. Taken together this thesis provides important insights in the regulation of cell survival in MM cells by IL-6 and IGF-I, and suggests possible regulators of sensitivity to induced apoptosis in MM.
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