Ultrathin compound semiconductor on insulator layers for high performance nanoscale transistors

Over the past several years, the inherent scaling limitations of electron devices have fueled the exploration of high carrier mobility semiconductors as a Si replacement to further enhance the device performance. In particular, compound semiconductors heterogeneously integrated on Si substrates have been actively studied, combining the high mobility of III-V semiconductors and the well-established, low cost processing of Si technology. This integration, however, presents significant challenges. Conventionally, heteroepitaxial growth of complex multilayers on Si has been explored. Besides complexity, high defect densities and junction leakage currents present limitations in the approach. Motivated by this challenge, here we utilize an epitaxial transfer method for the integration of ultrathin layers of single-crystalline InAs on Si/SiO2 substrates. As a parallel to silicon-on-insulator (SOI) technology14,we use the abbreviation "XOI" to represent our compound semiconductor-on-insulator platform. Through experiments and simulation, the electrical properties of InAs XOI transistors are explored, elucidating the critical role of quantum confinement in the transport properties of ultrathin XOI layers. Importantly, a high quality InAs/dielectric interface is obtained by the use of a novel thermally grown interfacial InAsOx layer (~1 nm thick). The fabricated FETs exhibit an impressive peak transconductance of ~1.6 mS/{\mu}m at VDS=0.5V with ON/OFF current ratio of greater than 10,000 and a subthreshold swing of 107-150 mV/decade for a channel length of ~0.5 {\mu}m

Downregulation of metastasis suppressor 1(MTSS1) is associated with nodal metastasis and poor outcome in Chinese patients with gastric cancer

<p>Abstract</p> <p>Background</p> <p>The putative tumor metastasis suppressor 1(MTSS1) is an actin-binding scaffold protein that has been implicated to play an important role in carcinogenesis and cancer metastasis, yet its role in the development of gastric cancer has not been well illustrated. In this study, we detected MTSS1 expression and explored its clinical significance in gastric cancer.</p> <p>Methods</p> <p>Immunohistochemistry was performed using tissue microarrays containing gastric adenocarcinoma specimens from 1,072 Chinese patients with normal adjacent mucosa, primary gastric cancer and lymph node (LN) metastasis and specific antibody against MTSS1. MTSS1 mRNA and protein expression were detected by reverse transcription-polymerase chain reaction and Western blotting. The clinical follow-up was done in the 669 patients living in Shanghai that was chose from the 1072 cases.</p> <p>Results</p> <p>Complete loss of MTSS1 expression was observed in 751 cases (70.1%) of the 1,072 primary tumors and 103 (88%) of 117 nodal metastases; and loss of MTSS1 expression was significantly associated with poorly differentiated tumors, large tumor size, deep invasion level, the presence of nodal metastases and advanced disease stage. Moreover, multivariate analysis demonstrated that loss of MTSS1 expression correlated significantly with poor survival rates (RR = 0.194, 95% CI = 0.144-0.261, P < 0.001).</p> <p>Conclusions</p> <p>MTSS1 expression decreased significantly as gastric cancer progressed and metastasized, suggesting MTSS1 may serve as a useful biomarker for the prediction of outcome of gastric cancer.</p

Expression of CDX2 and Hepatocyte Antigen in Benign and Malignant Lesions of Gallbladder and Its Correlation with Histopathologic Type and Clinical Outcome

Recent studies have shown that both CDX2 and Hepatocyte antigen (Hep) are detected in different types of cancer and associated with clinical prognosis. However, fever studies have examined gallbladder cancer specimens, and little is known about the clinicopathological significance of both CDX2 and Hep expression in gallbladder adenocarcinomas. In present study, we examined the expression frequencies of CDX2 and Hepatocyte antigen (Hep), and explored their clinicopathologic significances in gallbladder adenocarcinoma. Immunohistochemistry was used to detect and compare the frequencies of CDX2 and Hep expression in 108 samples of gallbladder adenocarcinoma, 46 peri-tumor tissues and 35 chronic cholecystitis. The expression frequencies for CDX2 and Hep were 49/108 (45.4%) and 45/108 (41.7%) in gallbladder carcinoma; 13/46 (28.3%) and 11/46 (23.9) in peri-tumor tissues; 5/35 (14.3%) and 2/35 (5.7%) in chronic cholecystitis. The positive staining of CDX2 or Hep in gallbladder adenocarcinoma was significantly higher than that in peritumoral tissues (both, P < 0.05), and chronic cholecystits (both, P < 0.01). The expression of CDX2 or Hep was negatively correlated to grade of differentiation, tumor size and lymph node metastasis (P < 0.01 or P < 0.05). Elevated expression frequency of CDX2 or Hep was associated with increased overall survival (P = 0.003 or P = 0.002). Multivariate Cox regression analysis showed that CDX2 (P = 0.014) or Hep (P = 0.026) expression was an independent prognostic predictor in gallbladder adenocarcinoma. CDX2 and Hep might function as important biological markers in the development and prognosis of gallbladder adenocarcinoma

Increased proportion of nitric oxide synthase immunoreactive neurons in rat ileal myenteric ganglia after severe acute pancreatitis

<p>Abstract</p> <p>Background</p> <p>Severe acute pancreatitis (SAP) remains a potentially life-threatening disease. Gastrointestinal motility disturbance such as intestinal ileus is seen in every case. By now, the mechanisms of pancreatitis-induced ileus are largely unknown. The main purpose of the present study was to observe changes of nitric oxide synthase-immunoreactive (NOS-IR) neurons in ileal myenteric ganglia in SAP rats with gastrointestinal dysmotility, trying to explore underlying nervous mechanisms of pancreatitis-induced ileus.</p> <p>Methods</p> <p>Twenty Sprague Dawley rats were randomly divided into sham operated group and SAP group. SAP was induced by retrograde cholangiopancreatic duct injection of 5% sodium taurocholate. Abdominal X-ray and intestinal transit were performed to detect the existence of paralytic ileus and intestinal dysmotility. Pathological damage of pancreas was evaluated. Double-immunolabeling was employed for the whole-mount preparations of ileal myenteric ganglia. The morphology of NOS-IR neurons were observed and the percentage of NOS-IR neurons was calculated based on the total Hu-immunoreactive neurons. Total RNA of ileum was extracted according to Trizol reagent protocol. Neuronal NOS (nNOS) mRNA expression was evaluated by RT-PCR.</p> <p>Results</p> <p>The small intestinal transit index in the SAP group was significantly lower compared with the sham operated group (29.21 ± 3.68% vs 52.48 ± 6.76%, <it>P <</it>0.01). The percentage of NOS-IR neurons in ileal myenteric ganglia in the SAP group was significantly higher than that in the sham operated group (37.5 ± 12.28% vs 26.32 ± 16.15%, <it>P <</it>0.01). nNOS mRNA expression in ileum of SAP group was significantly higher than that in the sham operated group (1.02 ± 0.10 vs 0.70 ± 0.06, <it>P </it>< 0.01).</p> <p>Conclusions</p> <p>The increased quantity of NOS-IR neurons in ileal myenteric ganglia and increased nNOS mRNA expression may suggest nNOS over expression as one of the nervous mechanisms of gastrointestinal dysmotility in SAP rat.</p

Adult Raphe-Specific Deletion of Lmx1b Leads to Central Serotonin Deficiency

The transcription factor Lmx1b is essential for the differentiation and survival of central serotonergic (5-HTergic) neurons during embryonic development. However, the role of Lmx1b in adult 5-HTergic neurons is unknown. We used an inducible Cre-LoxP system to selectively inactivate Lmx1b expression in the raphe nuclei of adult mice. Pet1-CreERT2 mice were generated and crossed with Lmx1bflox/flox mice to obtain Pet1-CreERT2; Lmx1bflox/flox mice (which termed as Lmx1b iCKO). After administration of tamoxifen, the level of 5-HT in the brain of Lmx1b iCKO mice was reduced to 60% of that in control mice, and the expression of tryptophan hydroxylase 2 (Tph2), serotonin transporter (Sert) and vesicular monoamine transporter 2 (Vmat2) was greatly down-regulated. On the other hand, the expression of dopamine and norepinephrine as well as aromatic L-amino acid decarboxylase (Aadc) and Pet1 was unchanged. Our results reveal that Lmx1b is required for the biosynthesis of 5-HT in adult mouse brain, and it may be involved in maintaining normal functions of central 5-HTergic neurons by regulating the expression of Tph2, Sert and Vmat2

Thalamic Activation Modulates the Responses of Neurons in Rat Primary Auditory Cortex: An In Vivo Intracellular Recording Study

Auditory cortical plasticity can be induced through various approaches. The medial geniculate body (MGB) of the auditory thalamus gates the ascending auditory inputs to the cortex. The thalamocortical system has been proposed to play a critical role in the responses of the auditory cortex (AC). In the present study, we investigated the cellular mechanism of the cortical activity, adopting an in vivo intracellular recording technique, recording from the primary auditory cortex (AI) while presenting an acoustic stimulus to the rat and electrically stimulating its MGB. We found that low-frequency stimuli enhanced the amplitudes of sound-evoked excitatory postsynaptic potentials (EPSPs) in AI neurons, whereas high-frequency stimuli depressed these auditory responses. The degree of this modulation depended on the intensities of the train stimuli as well as the intervals between the electrical stimulations and their paired sound stimulations. These findings may have implications regarding the basic mechanisms of MGB activation of auditory cortical plasticity and cortical signal processing