Pressure tunes electrical resistivity by four orders of magnitude in amorphous Ge2Sb2Te5 phase-change memory alloy.

Ge-Sb-Te-based phase-change memory is one of the most promising candidates to succeed the current flash memories. The application of phase-change materials for data storage and memory devices takes advantage of the fast phase transition (on the order of nanoseconds) and the large property contrasts (e.g., several orders of magnitude difference in electrical resistivity) between the amorphous and the crystalline states. Despite the importance of Ge-Sb-Te alloys and the intense research they have received, the possible phases in the temperature-pressure diagram, as well as the corresponding structure-property correlations, remain to be systematically explored. In this study, by subjecting the amorphous Ge(2)Sb(2)Te(5) (a-GST) to hydrostatic-like pressure (P), the thermodynamic variable alternative to temperature, we are able to tune its electrical resistivity by several orders of magnitude, similar to the resistivity contrast corresponding to the usually investigated amorphous-to-crystalline (a-GST to rock-salt GST) transition used in current phase-change memories. In particular, the electrical resistivity drops precipitously in the P = 0 to 8 GPa regime. A prominent structural signature representing the underlying evolution in atomic arrangements and bonding in this pressure regime, as revealed by the ab initio molecular dynamics simulations, is the reduction of low-electron-density regions, which contributes to the narrowing of band gap and delocalization of trapped electrons. At P > 8 GPa, we have observed major changes of the average local structures (bond angle and coordination numbers), gradually transforming the a-GST into a high-density, metallic-like state. This high-pressure glass is characterized by local motifs that bear similarities to the body-centered-cubic GST (bcc-GST) it eventually crystallizes into at 28 GPa, and hence represents a bcc-type polyamorph of a-GST.

Pressure-induced superconductivity in topological parent compound Bi2Te3.

We report a successful observation of pressure-induced superconductivity in a topological compound Bi(2)Te(3) with T(c) of ∼3 K between 3 to 6 GPa. The combined high-pressure structure investigations with synchrotron radiation indicated that the superconductivity occurred at the ambient phase without crystal structure phase transition. The Hall effects measurements indicated the hole-type carrier in the pressure-induced superconducting Bi(2)Te(3) single crystal. Consequently, the first-principles calculations based on the structural data obtained by the Rietveld refinement of X-ray diffraction patterns at high pressure showed that the electronic structure under pressure remained topologically nontrivial. The results suggested that topological superconductivity can be realized in Bi(2)Te(3) due to the proximity effect between superconducting bulk states and Dirac-type surface states. We also discuss the possibility that the bulk state could be a topological superconductor.

Overexpression of the growth arrest-specific homeobox gene Gax inhibits proliferation, migration, cell cycle progression, and apoptosis in serum-induced vascular smooth muscle cells.

The Gax gene has been implicated in a variety of cell-developmental and biological processes, and aberrant Gax expression is linked to many diseases. In this study, to provide important insights for Gax-based gene therapy in vein graft restenosis and its anti-restenotic mechanism, we used rabbit vascular smooth muscle cells (VSMCs) to investigate the effects of Gax overexpression on proliferation, migration, cell cycle, and apoptosis in a serum-stimulated culture. Rabbit VSMC lines that stably overexpressed Gax were established by transfection with recombinant adenoviral vector Ad5-Gax. The effect of Gax overexpression on in vitro serum-induced VSMCs proliferation, migration, cell cycle, and apoptosis was assessed by MTT, wound healing, and flow cytometry assays, respectively. To investigate the effect of Gax overexpression on PCNA and MMP-2 in serum-induced VSMCs, immunocytochemistry, RT-PCR, and gelatin zymography were performed. The results clearly showed that Gax overexpression decreases PCNA expression in serum-induced VSMCs. Gax overexpression also significantly inhibited cell proliferation by blocking entry into the S-phase of the cell cycle, promoted cell apoptosis, and reduced cell migration activity by downregulating MMP-2 release and activity. These findings indicate that Gax would be an optimal target gene for gene therapy to treat vein graft restenosis.

Pressure effect on the structural transition and suppression of the high-spin state in the triple-layer T'-La4Ni3O8.

We report a comprehensive high-pressure study on the triple-layer T'-La4Ni3O8 with a suite of experimental probes, including structure determination, magnetic, and transport properties up to 50 GPa. Consistent with a recent ab inito calculation, application of hydrostatic pressure suppresses an insulator-metal spin-state transition at P(c)≈6 GPa. However, a low-spin metallic phase does not emerge after the high-spin state is suppressed to the lowest temperature. For P>20 GPa, the ambient T' structure transforms gradually to a T(†)-type structure, which involves a structural reconstruction from fluorite La-O2-La blocks under low pressures to rock-salt LaO-LaO blocks under high pressures. Absence of the metallic phase under pressure has been discussed in terms of local displacements of O2- ions in the fluorite block under pressure before a global T(†) phase is established.

Reemergence of high-Tc superconductivity in the (Li1-xFe x )OHFe1-ySe under high pressure.

In order to elucidate pressure-induced second superconducting phase (SC-II) in A x Fe2-ySe2 (A = K, Rb, Cs, and Tl) having an intrinsic phase separation, we perform a detailed high-pressure magnetotransport study on the isoelectronic, phase-pure (Li1-xFe x )OHFe1-ySe single crystals. Here we show that its ambient-pressure superconducting phase (SC-I) with a critical temperature Tc ≈ 40 K is suppressed gradually to below 2 K and an SC-II phase emerges above Pc ≈ 5 GPa with Tc increasing progressively to above 50 K up to 12.5 GPa. Our high-precision resistivity data uncover a sharp transition of the normal state from Fermi liquid for SC-I to non-Fermi liquid for SC-II phase. In addition, the reemergence of high-Tc SC-II is found to accompany with a concurrent enhancement of electron carrier density. Without structural transition below 10 GPa, the observed SC-II with enhanced carrier density should be ascribed to an electronic origin presumably associated with pressure-induced Fermi surface reconstruction.

[Multicenter investigation of extracorporeal membrane oxygenation application in pediatric intensive care unit in China].

Objective: To survey the conduction and evaluate the effectiveness of extracorporeal membrane oxygenation (ECMO) therapy in pediatric intensive care unit (PICU) in China mainland. Methods: In a questionnaire-based survey, we retrospectively reviewed the application of ECMO in children's hospital and general hospital in China mainland to summarize and analyze the categories of diseases and prognosis of children treated with ECMO therapy. Results: By December 31, 2017, a total of 23 hospitals using ECMO, including 22 tertiary referral hospitals and 1 secondary hospital, among which 16 were children's hospitals and 7 were general hospitals. Thirty-seven ECMO equipment was available. A total of 518 patients treated with ECMO, within whom 323 (62.4%) successfully weaned from ECMO and 262 (50.6%) survived to discharge. Among 375 pediatric patients, 233 (62.1%) were successfully weaned from ECMO and 186 (49.6%) survived to discharge. Among 143 newborn patients, 90 (62.9%) successfully weaned from ECMO, 76 (53.1%) survived to discharge. ECMO was applied in veno-arterial (VA) mode to 501 (96.7%) patients, veno-venous (VV) mode to 14 (2.7%) patients, and VV-VA conversion mode to 3 (0.6%) patients. Sixty-nine patients required extracorporeal cardiopulmonary resuscitation (ECPR), including 20 newborn patients (29.0%) and 38 pediatric patients (71.0%), who were all with cardiovascular disease. Neonatal respiratory distress syndrome (26/61), persistent pulmonary hypertension of the newborn (PPHN) (12/61), and meconium aspiration syndrome (MAS) (11/61) are the most common pulmonary diseases in newborn patients; among whom, infants with PPHN had highest survival rate (10/12), followed by MAS (9/11). Among newborn patients with cardiovascular diseases, those who admitted were after surgery for congenital cardiac disease were the most common (54/82), while those with septic shock had the highest survival rate (2/3). In pediatric pulmonary diseases, acute respiratory distress syndrome was the most common (42/93), while plastic bronchitis was with the highest survival rate (4/4), followed by viral pneumonia (13/16). Among pediatric cardiovascular diseases, congenital cardiac defect was the most common (124/282), while fulminant myocarditis had the highest survival rate (54/77). Conclusion: The application of ECMO as a rescue therapy for children with severe cardiopulmonary failure has dramatically developed in China mainland.

Targeting colon cancer stem cells with novel blood cholesterol drug pitavastatin.

OBJECTIVE: Previous studies have demonstrated the importance of stem cells in human cancer, including colon cancer. Pitavastatin is approved for the treatment of hyperlipidemia and has also been shown to inhibit stem cell proliferation in preliminary in vitro studies. This study was done to investigate the effects of pitavastatin on human colon carcinoma stem cells (coCSCs) in vitro and in mouse tumor xenografts in vivo. MATERIALS AND METHODS: Human colon adenocarcinoma cell lines, SW480 and SW620, were cultured to the spheroid formation. The effects of pitavastatin on colon cancer stem cells were studied using the colorimetric MTT cell proliferation assay; quantitative polymerase chain reaction was used to determine the expression of cell cycle genes, OCT4, SOX2, and NANOG; Western blots were performed to measure MDR1. Mice were injected subcutaneously with SW480 cells; the growth of these tumor xenografts was studied using volumetric analysis following pitavastatin treatment. RESULTS: Specific cell culture medium provided conditions that resulted in the expression of colon cancer stem cell markers when compared with normal cultured cells. Colon cancer stem cells were inhibited by pitavastatin treatment. Pitavastatin reduced the expression of stem cell markers of colon cancer stem cells and induced the cell apoptosis. Pitavastatin inhibited the growth of mouse tumor xenografts. CONCLUSIONS: The findings of this preliminary study have demonstrated a potential role for pitavastatin in the inhibition of stem cell proliferation in colon carcinoma. Further studies are recommended to determine the mechanism of these effects on colon carcinoma cells in vitro and in vivo.

Superconductivity Bordering Rashba Type Topological Transition.

Strong spin orbital interaction (SOI) can induce unique quantum phenomena such as topological insulators, the Rashba effect, or p-wave superconductivity. Combining these three quantum phenomena into a single compound has important scientific implications. Here we report experimental observations of consecutive quantum phase transitions from a Rashba type topological trivial phase to topological insulator state then further proceeding to superconductivity in a SOI compound BiTeI tuned via pressures. The electrical resistivity measurement with V shape change signals the transition from a Rashba type topological trivial to a topological insulator phase at 2 GPa, which is caused by an energy gap close then reopen with band inverse. Superconducting transition appears at 8 GPa with a critical temperature TC of 5.3 K. Structure refinements indicate that the consecutive phase transitions are correlated to the changes in the Bi-Te bond and bond angle as function of pressures. The Hall Effect measurements reveal an intimate relationship between superconductivity and the unusual change in carrier density that points to possible unconventional superconductivity.

Superconductivity in HfTe5 across weak to strong topological insulator transition induced via pressures.

Recently, theoretical studies show that layered HfTe5 is at the boundary of weak &strong topological insulator (TI) and might crossover to a Dirac semimetal state by changing lattice parameters. The topological properties of 3D stacked HfTe5 are expected hence to be sensitive to pressures tuning. Here, we report pressure induced phase evolution in both electronic &crystal structures for HfTe5 with a culmination of pressure induced superconductivity. Our experiments indicated that the temperature for anomaly resistance peak (Tp) due to Lifshitz transition decreases first before climbs up to a maximum with pressure while the Tp minimum corresponds to the transition from a weak TI to strong TI. The HfTe5 crystal becomes superconductive above ~5.5 GPa where the Tp reaches maximum. The highest superconducting transition temperature (Tc) around 5 K was achieved at 20 GPa. Crystal structure studies indicate that HfTe5 transforms from a Cmcm phase across a monoclinic C2/m phase then to a P-1 phase with increasing pressure. Based on transport, structure studies a comprehensive phase diagram of HfTe5 is constructed as function of pressure. The work provides valuable experimental insights into the evolution on how to proceed from a weak TI precursor across a strong TI to superconductors.

Polymorphic phase transition mechanism of compressed coesite.

Silicon dioxide is one of the most abundant natural compounds. Polymorphs of SiO2 and their phase transitions have long been a focus of great interest and intense theoretical and experimental pursuits. Here, compressing single-crystal coesite SiO2 under hydrostatic pressures of 26-53 GPa at room temperature, we discover a new polymorphic phase transition mechanism of coesite to post-stishovite, by means of single-crystal synchrotron X-ray diffraction experiment and first-principles computational modelling. The transition features the formation of multiple previously unknown triclinic phases of SiO2 on the transition pathway as structural intermediates. Coexistence of the low-symmetry phases results in extensive splitting of the original coesite X-ray diffraction peaks that appear as dramatic peak broadening and weakening, resembling an amorphous material. This work sheds light on the long-debated pressure-induced amorphization phenomenon of SiO2, but also provides new insights into the densification mechanism of tetrahedrally bonded structures common in nature.

Albendazole chemotherapy for human cystic and alveolar echinococcosis in north-western China.

Human echinococcosis is highly endemic in north-western China; the main treatment is by surgery. In this paper, we report the results of chemotherapy with albendazole (ABZ), 15-20 mg/kg/d orally, for 30 d with intervals of 10 d between treatments for 3-6 courses. For multi-organ cystic echinococcosis (CE) and alveolar echinococcosis (AE), patients were given 12-18 courses of ABZ. Patients were divided into 4 groups: (i) ABZ surgery group, albendazole with surgery for 21 CE cases: (ii) non-ABZ surgery group, 80 CE cases treated by surgery alone; (iii) ABZ CE group, albendazole treatment alone in 58 CE cases, and (iv) ABZ AE group, 14 AE patients treated by albendazole and surgical intervention and 5 AE patients treated by albendazole alone. Twenty-seven of 34 (79.4%) cysts in group (i) patients showed increased necrotic changes and decreased viability of the cysts compared to group (ii). However, 10 of 84 (11.9%) cysts in group (ii) patients showed spontaneous evidence of necrosis at surgery. In group (iii), ABZ treatment alone was successful in 14 (24.1%), resulted in improvement in 29 (50%) and had no effect in 15 (25.9%) patients. Seven cases in group (iv) improved, with diminished size of lesions which were non-viable. The remaining 7 cases in group (iv) showed evidence of cyst viability at surgery; 2 could not be saved after a further 15 courses of albendazole. Of the five AE patients in group (iv) who received only ABZ, one improved, 2 stabilized, one deteriorated and one died. Albendazole chemotherapy, while not completely effective, has an important role in treatment of both cystic and alveolar echinococcosis.

Cystic echinococcosis in semi-nomadic pastoral communities in north-west China.

In order to determine the prevalence of human cystic echinococcosis (CE) in semi-nomadic traditional pastoralist groups in north-west China, 2 large community studies were undertaken in Altai and Tacheng Prefectures in 1990/91 and 1995/96, respectively. The Kekergash community (Altai) comprised mainly ethnic Kazakhs, whereas the Narenhebuke community (Tacheng) comprised mainly Mongolians. Populations were screened for CE by abdominal ultrasound scan (US) and serological tests. The total prevalence of confirmed human CE was higher in Narenhebuke (2.7%, 49/1844) than in Kekergash (0.9%, 17/1861; P < 0.01). Within each community there was no significant difference of CE prevalence between the Kazakh and Mongolian groups, although Han Chinese exhibited twice the rate of CE (4.9%) in Narenhebuke compared to the dominant Mongolian population. For each community, human CE prevalence increased with age and there was a greater risk associated with the practice of home slaughter of livestock. Dogs were screened for Echinococcus granulosus infection and re-infection levels using a highly specific coproantigen test. The proportion of dogs with positive coproantigen tests was significantly higher in Narenhebuke (36.0%, 50/139) compared to Kekergash (17.8%, 16/90). In Narenhebuke the re-infection levels of dogs, as determined by coproantigen positivity, were higher in the winter quarters (49.4%, 39/79) compared to the summer quarters (18.3%, 11/60; P < 0.01). Furthermore, coproantigen re-test positivity was 25% at 3 months and 29.2% at 7 months. Highest dog coproantigen positivity was obtained over the winter period.

Public health importance of cystic echinococcosis in China.

Cystic echinococcosis has been recorded in 21 out of China's 31 provinces, autonomous regions and municipalities (approximately 87% of territory). It constitutes one of the major public health problems, especially in several northwestern provinces and autonomous regions. This paper reviews the general situation, diagnosis, treatment, education and control programmes and international cooperation. Special attention is given to the Xinjiang, an endemic area about one sixth of the country's area with a human population of approximately 16 million.

Construction of retroviral vector carrying HSV-tk gene under control of human AFP enhancer core sequence and human pgk promotor.

AIM: To construct retroviral vector bringing HSV-tk gene under control of human AFP enhancer core sequence and human pgk promoter. METHODS: Internal SV40 promoter was deleted by SalI from retroviral vector pMNSM to construct pMNM. HSV-tk gene driven by pgk promoter was released by BamH I from an eukaryotic expression vector pBPGK-tk, and inserted into polylinker site of pMNM to construct pMNP-tk retroviral vector. Human α-fetoprotein gene enhancer core sequence was released by EcoR I from pGEM. 7Z-AFPe plasmid was inserted into the immediate upstream of pgk promoter of pMNP-tk vector. Construction of hepatoma specific retroviral vector pMNAP-tk was completed. RESULTS: The structure of pMNP-tk and pMNAP-tk vector was confirmed by restriction analysis. CONCLUSION: The vector is of great significance for hepatoma specific prodrug transformation gene therapy.

Symptomatic tracheal stenosis in burns.

Tracheal stenosis in burns is rare and usually results from prolonged intubation or tracheostomy. Inhalation injury itself has the potential risk of tracheal stenosis. We reviewed the records of 1878 burn patients during 1987 to 1995 and found seven with tracheal stenosis (0.37%) after an average of 4.4 years follow up. There were 4 males and 3 females with an average age of 27.3 years. The tracheal stenosis developed 1-22 months after burn (average 7 months). Five patients had their inhalation injury confirmed by bronchoscopic examination. The incidence of tracheal stenosis among inhalation injury patients was 5.49% (5/92). Six patients needed intubation in the initial stage either for respiratory distress or prophylaxis, with an average duration of 195.2 h. In addition to prolonged intubation, the presence of inhalation injury, repeated intubations and severe neck scar contractures are also contributors to tracheal stenosis in burns. We favor T-tube insertion as the first treatment choice; permanent tracheostomy was unsatisfactory in our study.

[Observation of the effects of LAK/IL-2 therapy combining with Lycium barbarum polysaccharides in the treatment of 75 cancer patients].

Seventy nine advanced cancer patients in a clinical trial were treated with LAK/IL-2 combining with Lycium Barbarum polysaccharides (LBP). Initial results of the treatment from 75 evaluable patients indicated that objective regression of cancer was achieved in patients with malignant melanoma, renal cell carcinoma, colorectal carcinoma, lung cancer, nasopharyngeal carcinoma, malignant hydrothorax. The response rate of patients treated with LAK/IL-2 plus LBP was 40.9% while that of patients treated with LAK/IL-2 was 16.1% (P < 0.05). The mean remission in patients treated with LAK/IL-2 plus LBP also lasted significantly longer. LAK/IL-2 plus LBP treatment led to more marked increase in NK and LAK cell activity than LAK/IL-2 without LBP. The results indicate that LBP can be used as an adjuvant in the biotherapy of cancer.

Superconductivity in strong spin orbital coupling compound Sb2Se3.

Recently, A2B3 type strong spin orbital coupling compounds such as Bi2Te3, Bi2Se3 and Sb2Te3 were theoretically predicated to be topological insulators and demonstrated through experimental efforts. The counterpart compound Sb2Se3 on the other hand was found to be topological trivial, but further theoretical studies indicated that the pressure might induce Sb2Se3 into a topological nontrivial state. Here, we report on the discovery of superconductivity in Sb2Se3 single crystal induced via pressure. Our experiments indicated that Sb2Se3 became superconductive at high pressures above 10 GPa proceeded by a pressure induced insulator to metal like transition at ~3 GPa which should be related to the topological quantum transition. The superconducting transition temperature (TC) increased to around 8.0 K with pressure up to 40 GPa while it keeps ambient structure. High pressure Raman revealed that new modes appeared around 10 GPa and 20 GPa, respectively, which correspond to occurrence of superconductivity and to the change of TC slop as the function of high pressure in conjunction with the evolutions of structural parameters at high pressures.

Superconductivity of the topological insulator Bi2Se3 at high pressure.

The pressure-induced superconductivity and structural evolution of Bi2Se3 single crystals are studied. The emergence of superconductivity at an onset transition temperature (Tc) of about 4.4 K is observed at around 12 GPa. Tc increases rapidly to a maximum of 8.2 K at 17.2 GPa, decreases to around 6.5 K at 23 GPa, and then remains almost constant with further increases in pressure. Variations in Tc with respect to pressure are closely related to the carrier density, which increases by over two orders of magnitude from 2 to 23 GPa. High-pressure synchrotron radiation measurements reveal structural transitions at around 12, 20, and above 29 GPa. A phase diagram of superconductivity versus pressure is also constructed.

Superconductivity in topological insulator Sb2Te3 induced by pressure.

Topological superconductivity is one of most fascinating properties of topological quantum matters that was theoretically proposed and can support Majorana Fermions at the edge state. Superconductivity was previously realized in a Cu-intercalated Bi2Se3 topological compound or a Bi2Te3 topological compound at high pressure. Here we report the discovery of superconductivity in the topological compound Sb2Te3 when pressure was applied. The crystal structure analysis results reveal that superconductivity at a low-pressure range occurs at the ambient phase. The Hall coefficient measurements indicate the change of p-type carriers at a low-pressure range within the ambient phase, into n-type at higher pressures, showing intimate relation to superconducting transition temperature. The first principle calculations based on experimental measurements of the crystal lattice show that Sb2Te3 retains its Dirac surface states within the low-pressure ambient phase where superconductivity was observed, which indicates a strong relationship between superconductivity and topology nature.