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The effect of proton irradiation on the electrical properties of AlGaN/GaN high electron mobility transistors (HEMTs) with hydrogen treatment is studied. Hydrogen treatment makes the damage caused by proton irradiation worse. The AlGaN/GaN HEMTs with hydrogen treatment at $2.0 \times 10^{14}\text{p}$ /cm2 3-MeV proton irradiation fluence experience a decrease by 37.3% in the saturation current, a 0.55V positive shift of the threshold voltage ( V $_{th}$ ) and a notable decrease in reverse gate leakage current. While the AlGaN/GaN HEMTs without hydrogen treatment experience a decrease by 18.2% in the saturation current, a 0.211V positive shift of the V $_{th}$ . After extracted by the Low Frequency Noise method (LFN method), the flat-band voltage noise power spectral density ( S $_{Vfb}$ ) after hydrogen treatment decreases, and proton irradiation makes the number of defects increased. But the hydrogen treatment causes the S $_{Vfb}$ to rise rapidly after proton irradiation, comparing with the AlGaN/GaN HEMTs without hydrogen treatment. The main mechanism can be attributed to the hydrogen passivation defect and proton irradiation to stimulate the passivation defect to produce composite defects. And the AlGaN/GaN HEMTs with hydrogen treatment is more sensitive to proton irradiation, compared with the AlGaN/GaN HEMTs without hydrogen treatment.

Heavy ion-induced electrical degradations and mechanisms of high-electron-mobility transistors (HEMTs) were investigated in this article. AlGaN/GaN HEMTs were irradiated by 800-MeV Bi ions with total fluence of $5.23\times 10^{{10}}$ ions/cm2. The results show that the saturation current decreased by 13.1%, the threshold voltage negatively shifted by 0.21 V, the peak transconductance decreased by 26.6%, the reverse gate-leakage current increased much more than 16 times, and forward gate-leakage current increased more than three times. Furthermore, all electrical performances experienced partial recovery after room temperature annealing (RTA) and 175 °C thermal annealing except gate-leakage current. To further explore the mechanism of gate-leakage degradation, AlGaN/GaN heterojunction wafers were exposed to 1400-MeV Ta ions with fluence of $6.86\times107$ ions/cm2, and characterized by conductive atomic force microscope (CAFM) before and after the irradiation. The results show that the leakage current significantly increased in AlGaN material areas after the irradiation. Comparing the increase in gate leakage of the AlGaN/GaN heterojunction and AlGaN/GaN HEMT induced by heavy ions irradiation, it can be seen that the gate-leakage current of AlGaN/GaN HEMT after heavy irradiation almost entirely was caused by latent tracks. The mechanism for the irreversible increase in gate leakage after heavy ions irradiation could be attributed to the latent tracks along the ion trajectories through the heterojunction.

To explore the role of hydrogen in radiation degradation of AlGaN/GaN high-electron-mobility transistors (HEMTs), the performance degradation of the hydrogen untreated and pretreated devices is compared under the exposure of carbon ions. The energy of carbon ions is chosen as 7.6 MeV, and the maximum fluence reaches $4 \times 10^{12}$ cm−2. By electrical character measuring, it is found that the positive shift of the threshold voltage and the decrease of the transconductance occur after to the irradiation. Hydrogen pretreatment accelerates the shift of threshold voltage and the decrease of the transconductance. The threshold voltage of the device is almost unchanged under 1-MeV electron irradiations. This means that the displacement damage leads to the shift of the threshold voltage. The height of Schottky barrier hardly changes in the hydrogen pretreated devices, showing that the ionization defects such as the formation of interface states under the gate are not the main cause of device degradation. Deep level transient spectrum (DLTS) results show that the irradiations cause the increase of gallium vacancies, and the hydrogen pretreatment inhibits its formation. According to the first principle calculation, the existence of hydrogen in GaN layer can reduce the formation energy of and the number of charges of the defects. It is speculated that hydrogen atoms participate in the evolution of radiation defects, which changes the types and number of defects in the devices.

The single event burnout (SEB) effects of SiC power MOSFET are investigated by irradiations. An SEB is observed when drain biased above 400 V for 181Ta ion irradiation. The failure analysis shows a melting “hole” near the gate region due to the thermal runaway. Based on TCAD simulations, the impact ionization and parasitic bipolar are the key factors to trigger SEB in SiC MOSFET. Unlike the impact ionization, the turning on of the parasitic bipolar is not necessary for an SEB. But it will significantly reduce the threshold of SEB. Except for SEB, another permanent damage mode is also observed, which is manifested as the increase of leakage current and the abnormal of the output characteristics. This damage may be related to the latent track produced by heavy ion according to the failure analysis. The SEBs are observed for proton irradiations. The maximum LET value of the proton‐induced secondary ions can reach 13.9 MeV cm2/mg for 100 MeV proton. The simulations imply that most of the secondary ions can contribute to SEB. The biggest discrepancy from heavy ion irradiation is that no leakage current increases and output characteristics degradations are observed for the device without SEB after proton irradiation.

Results of laser-induced single event upset testing of devices with embedded error correction codes are described. Specifically, the memory system, consisting of a Micron MT41K256M16TW-107 IT: P 32 Meg×16×8 banks Dual Dynamic Random Access Memories (DDRs) was tested on a self-made test board. Two samples of each memory system or device type were irradiated with a pulsed laser. The units were irradiated by using a continual read/write correct loop in several bit patterns. Results for both correctable and uncorrectable errors are presented along with soft error data records.

Electron traps in AlGaN/GaN high electron mobility transistors were studied by combining theoretical and experimental methods. Energy levels about EC-0.9 eV due to irradiation are identified by deep-level transient spectroscopy (DLTS). Two electron traps, H1 (EC-0.63 eV) and H2 (EC-0.9 eV), were observed in the DLTS spectra. H1 was produced in device or material manufacturing, and H2 was caused by displacement damage. First, we reported that the signal peak of H2 can contribute from three defects labeled H2-1, H2-2, and H2-3 with energies EC-0.77 eV, EC-0.9 eV, and EC-0.98 eV, respectively. According to defect migration temperature and first principles calculation results, it is found that different configurations of di-nitrogen vacancy structures are the source of EC-0.77 eV and EC-0.9 eV signals. The defect of EC-0.98 eV is more stable at high temperatures, which may be related to gallium vacancy.

The water ice on the moon is the key to reveal the origin and evolution of the moon, and it is also an important part of the moon's resources. It is very important to accurately detect the distribution and content of water ice. This article focuses on the satellites and related data sets related to water ice detection in various countries around the world, in-depth investigation and analysis of the current research status and progress of water ice detection and inversion at home and abroad, and classified into radar, neutron, reflectivity according to the data type The inversion points out the limitations and future development directions of various methods.

Degradation characteristics and mechanisms of AlGaN/GaN high electron mobility transistors (HEMTs) were investigated under swift heavy-ion irradiation. AlGaN/GaN HEMTs were exposed to 800 MeV Bi ions with fluence up to 5.28 × 10 10 ions/cm 2 . Post-irradiation measurement shows that the saturation drain current reduced by 15%, the maximum transconductance decreased by more than 27%, and both the positive and negative gate characteristics degraded dramatically. By the off-state examination using the Photo Emission Microscopy (PEM), electroluminescence hot spots were found in the gate areas, which indicates new leakage passages produced by heavy-ion bombardment. Micro cross sections were prepared at hot spot areas by dual-beam focused ion beam (FIB) and examined using transmission electron microscope (TEM). The presence of latent tracks throughout the whole hetero-junction area was confirmed. Latent tracks, which related to the high density ionizing energy-loss, play a role of new leakage paths and account for the increment of gate leakage. Moreover, nonionizing energy-loss induced defects decrease the charge density in the two-dimensional electron gas (2DEG) and reduce the carrier mobility, leading to the degradation of device output performances.

Background.Microglial activation contributes to neuroinflammation and neuronal damage in neurodegenerative disorders including Alzheimer’s and Parkinson’s diseases. It has been suggested that neurodegenerative disorders may be improved if neuroinflammation can be controlled.trans-cinnamaldehyde (TCA) isolated from the stem bark ofCinnamomum cassiapossesses potent anti-inflammatory capability; we thus tested whether TCA presents neuroprotective effects on improving neuronal survival by inhibiting neuroinflammatory responses in BV2 microglial cells.Results.To determine the molecular mechanism behind TCA-mediated neuroprotective effects, we assessed the effects of TCA on lipopolysaccharide- (LPS-) induced proinflammatory responses in BV2 microglial cells. While LPS potently induced the production and expression upregulation of proinflammatory mediators, including NO, iNOS, COX-2, IL-1β, and TNF-α, TCA pretreatment significantly inhibited LPS-induced production of NO and expression of iNOS, COX-2, and IL-1βand recovered the morphological changes in BV2 cells. TCA markedly attenuated microglial activation and neuroinflammation by blocking nuclear factor kappa B (NF-κB) signaling pathway. With the aid of microglia and neuron coculture system, we showed that TCA greatly reduced LPS-elicited neuronal death and exerted neuroprotective effects.Conclusions.Our results suggest that TCA, a natural product, has the potential of being used as a therapeutic agent against neuroinflammation for ameliorating neurodegenerative disorders.

Microglia activation and neuroinflammation are critically involved in pathogenesis of neurodegenerative disorders. Patients with neurodegenerative disorders often suffer memory impairment and currently there is no effective treatment for inflammation-led memory impairment. Trans-cinnamaldehyde (TCA) isolated from medicinal herb Cinnamomum cassia has been shown to exhibit anti-inflammatory capability. However, the potential of TCA to be used to improve memory impairment under neuroinflammation has not been explored. Primary microglia stimulated by lipopolysaccharide (LPS) were used to evaluate the potential anti-neuroinflammatory effects of TCA by examining the production of nitric oxide (NO), expression of inducible nitric oxide synthase (iNOS), pro-inflammatory cytokines, and activation of MAPKs. A mouse model of LPS-induced memory impairment was established to assess the neuroprotective effects of TCA against memory deficit and synaptic plasticity inhibition by both behavioral tests and electrophysiological recordings. TCA pretreatment decreased LPS-induced morphological changes, NO production and IL-1β release in primary microglia. Decreased NO production was due to the accelerated degradation of iNOS mRNA in LPS-stimulated microglia through TCA's inhibitory effect on MEK1/2-ERK1/2 signaling pathway. TCA was able to reduce the levels of iNOS and phosphorylated ERK1/2 in hippocampus of mice challenged with LPS. Most importantly, TCA significantly lessened memory deficit and improved synaptic plasticity in LPS-challenged mice. This study demonstrates that TCA suppressed microglial activation by destabilizing iNOS mRNA, which leads to improved memory impairment in mice suffering neuroinflammation.

In China, fast increase in passenger vehicles has procured the growing concern about vehicle exhausts as an important source of anthropogenic secondary organic aerosols (SOA) in megacities hard-hit by haze. However, there are still no chamber simulation studies in China on SOA formation from vehicle exhausts. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with the relative humidity around 50%. After aging at an OH exposure of 5 × 106 molecules cm−3 h, the formed SOA was 12–259 times as high as primary OA (POA). The SOA production factors (PF) were 0.001–0.044 g kg−1 fuel, comparable with those from the previous studies at the quite similar OH exposure. This quite lower OH exposure than that in typical atmospheric condition might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yield data in this study were well fit by a one-product gas-particle partitioning model and quite lower than those of a previous study investigating SOA formation form three idling passenger vehicles (Euro 2–Euro 4). Traditional single-ring aromatic precursors and naphthalene could explain 51–90% of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C/ΔO : C ranged from −0.59 to −0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.

Experimental evidences are presented showing the variety of supply voltage dependence of single event upset (SEU) sensitivity in diverse SRAM devices. Devices under test (DUTs) from Alliance Memory, ISSI and IDT companies with different technologies were irradiated by several kinds of heavy ions at Heavy ion Research Facility in Lanzhou (HIRFL) cyclotrons. For the Alliance 256 kb SRAM device, SEU cross section increases by more than one order of magnitude as supply voltage decreases from 5.0 V to 3.0 V. SEU data of Alliance 64 kb SRAM also exhibits significant supply voltage dependence. The reduction of critical charge is the predominant factor worsening the device performance. While for the Alliance 8 Mb, ISSI 2 Mb and IDT 256 kb SRAM devices, no obvious trend was observed, which is attributed to the negligible net contribution of competing mechanisms. Those results suggest that the worst-case supply voltage for evaluation of SEU sensitivity depends on the test devices.

Open source GIS (OSG) is a fast developing field. When OSG is combined with Web2.0 and Service Orientated Architectures (SOA) technologies and more applications of Public Participation GIS, it has many advantages over commercial GIS software. Despite this, OSG still needs more improvement in terms of stability and functional integrity. In order to build more robust, more practical, and more functional LBS applications, this research investigates pedestrian-orientated wayfinding, with special requirements as its study topic. We describe some Web 2.0 routing APIs which can be easily used to provide general shortest path planning. However, these APIs cannot provide guidance services for specific user groups with special requirements, such as tourists in small towns. We take Maynooth as case-study. Maynooth is the only University town in Ireland with a population of approximately 20,000. This research uses OpenStreetMap (OSM) as spatial data source. OSM contains very spatially rich dataset. It is stored and managed in PostGIS/PostgreSQL. Through previous work on LBS applications using the CloudMade Routing API and OSM data, we present a Java-based wayfinding module implementing a restricted area version of Dijkstra algorithm. A set of native PostGIS spatial functions are used to improve performance of the routing algorithm. Results from our wayfinding algorithm are presented and compared with those obtained by using the CloudMade Routing API. Our results are promising and show that this special version of Dijkstra algorithm can take advantage of the spatial data stored in OSM. This work provides a base to build more effective pedestrian wayfinding algorithms which can be implemented in open source software and open APIs. This approach provides a feasible and economical LBS solution for small towns, villages and tourism regions outside larger cities.