Probing 2D sub-bands of bi-layer graphene

Investigations of Raman spectra and surface enhanced Raman spectra (SERS) of supported and suspended bilayer graphene were realized.

Surface-enhanced Raman scattering of suspended monolayer graphene

The interactions between phonons and electrons induced by the dopants or the substrate of graphene in spectroscopic investigation reveal a rich source of interesting physics. Raman spectra and surface-enhanced Raman spectra of supported and suspended monolayer graphenes were measured and analyzed systemically with different approaches. The weak Raman signals are greatly enhanced by the ability of surface-enhanced Raman spectroscopy which has attracted considerable interests. The technique is regarded as wonderful and useful tool, but the dopants that are produced by depositing metallic nanoparticles may affect the electron scattering processes of graphene. Therefore, the doping and substrate influences on graphene are also important issues to be investigated. In this work, the peak positions of G peak and 2D peak, the I2D/IG ratios, and enhancements of G and 2D bands with suspended and supported graphene flakes were measured and analyzed. The peak shifts of G and 2D bands between the Raman and SERS signals demonstrate the doping effect induced by silver nanoparticles by n-doping. The I2D/IG ratio can provide a more sensitive method to carry out the doping effect on the graphene surface than the peak shifts of G and 2D bands. The enhancements of 2D band of suspended and supported graphenes reached 138, and those of G band reached at least 169. Their good enhancements are helpful to measure the optical properties of graphene. The different substrates that covered the graphene surface with doping effect are more sensitive to the enhancements of G band with respect to 2D band. It provides us a new method to distinguish the substrate and doping effect on graphene. PACS: 78.67.Wj (optical properties of graphene); 74.25.nd (Raman and optical spectroscopy); 63.22.Rc (phonons in graphene).

The anti-tumoral efficacy of a docetaxel-loaded liposomal drug delivery system modified with transferrin for ovarian cancer

To reduce the toxic effect on normal cells and improve the treatment effects of docetaxel, a novel transferrin modified docetaxel-loaded long circulating liposome for ovarian tumor was established for the first time. The transferrin-modified long-circulating liposomes loaded with docetaxel (TF-LP-DOC) were prepared by the post-insertion method and exhibited excellent characteristics in terms of particle size, encapsulation efficiency and stability. We investigated the targeting efficiencies of liposomes by the cellular uptake in vitro and biodistribution in vivo, and identified the therapeutic effects using cytotoxicity experiment (in vitro)and tumor growth inhibition (in vivo) on ovarian cancer. The in vitro and in vivo results showed that TF-LP-DOC were successfully established and presented an enhanced targeting ability. With decreased side effect and improved anti-tumor efficacy of chemotherapeutic drugs, TF-LP-DOC proved itself to be a very promising tumor targeted drug delivery system.

Revealing anisotropic strain in exfoliated graphene by polarized Raman spectroscopy

We report on a polarized Raman study on mechanically cleaved single-layer graphene films. Under a specific orientation of scattering measurement, the width and position of the G peak change with the incident polarization direction, while the integrated intensity of that is unaltered. This phenomenon is explained by a proposed mode in which the peak is contributed by a mixture of un-, compressive-, and tensile-strained G sub-modes. The compression and tension are both uniaxial and approximately perpendicular to each other. They are undesigned and located in either separated or overlapped sub-areas within the probed local region. Compared to the unstrained wavenumber of 1580 cm(-1), compression induces a blue shift while tension causes a red one. The sub-modes correlated with the light polarization through different relationships split the G peak into three sub-ones. We develop a method to quantitatively analyze the positions, widths, intensities, and polarization dependences of sub-peaks. This analysis quantitatively reveals local strain, which changes with the detected area of a graphene film. The method presented here can be extended to detect the strain distribution in the film and thus is a promising technology for graphene characterization.

Terbinafine inhibits KSR1 and suppresses Raf-MEK-ERK signaling in oral squamous cell carcinoma cells

Terbinafine inhibits the proliferation of many types of cancer cells, but the underlying mechanism remains to be determined. By computer simulation, we found that kinase suppressor of Ras 1 (KSR1) is a possible target of terbinafine. Treatment of human oral squamous cell carcinoma (OSCC) KB cells with either terbinafine or siRNA to knockdown KSR1 reduced proliferation and induced apoptosis, which was accompanied by suppression of the Raf-MEK-ERK pathway. In vivo, KSR1 expression was significantly associated with the clinical staging of OSCC and the smoking habit of patients. Kaplan Meyer survival analysis demonstrated that the cumulative survival time of patients without KSR1 expression was significantly longer than those with KSR1 overexpression. Our data provide the basis for developing terbinafine to treat OSCC.

Effects of minimally invasive percutaneous and trans-spatium intermuscular short-segment pedicle instrumentation on thoracolumbar mono-segmental vertebral fractures without neurological compromise

OBJECTIVE

To compare the outcomes of minimally invasive percutaneous short-segment pedicle instrumentation (SSPI) with that of trans-spatium intermuscular SSPI on thoracolumbar mono-segmental vertebral fracture without neurological compromise.

METHODS

A total of 39 patients with thoracolumbar mono-segmental vertebral fracture without neurological deficit receiving treatment between January 2009 and July 2011 were enrolled. Percutaneous SSPI was performed for 18 patients (the percutaneous group), and trans-spatium intermuscular SSPI was performed for 21 patients (the trans-spatium intermuscular group). Peroperative indices, intraoperative radiation exposure time, postoperative and follow-up lumbodorsal pain, function scores, and radiological data were compared.

RESULTS

The percutaneous group had significantly less intraoperative blood loss and less severe postoperative pains, but suffered significantly longer fluoroscopy time and higher hospitalization costs compared with the trans-spatium intermuscular group. No significant difference was observed in operating time. All patients were followed up for 17.3 ± 9.2 months (ranging from 5 to 35 months). No significant differences were observed between the two groups in terms of postoperative relative vertebral height (RVH) and regional kyphotic angle (RKA), as well as last follow-up RVH, RKA, lumbodorsal pain, and Oswestry disability index.

CONCLUSION

Percutaneous SSPI has the virtues of less intraoperative blood loss and less severe pains in the treatment of thoracolumbar mono-segmental vertebral fracture without neurological deficit. When compared with trans-spatium intermuscular SSPI, it results in longer intraoperative radiation exposure time and a higher surgery cost. To us, percutaneous SSPI has no advantage over trans-spatium intermuscular SSPI in therapeutic outcomes.

LEVEL OF EVIDENCE

Level IV. Retrospective study.

Levobupivacaine for postoperative epidural analgesia in orthopaedic surgery

INTRODUCTION

Levobupivacaine is the S(-)enantiomer of bupivacaine, a long acting amino-ester local anaesthetic agent. Cocktail mixture of levobupivacaine and fentanyl infusion is commonly given via epidural for post-operative analgesia. The concentration of levobupivacaine for optimal pain relief with least side effects remained uncertain.

MATERIALS AND METHODS

This was a prospective, randomized double-blind study to evaluate the effectiveness and safety of two different concentrations of levobupivacaine as epidural infusion for postoperative pain relief. Fifty patients who underwent orthopaedic lower limb surgeries were recruited and given a standardized combined spinal epidural anaesthesia during operation. They were then allocated to receive either 0.1% (Group A) or 0.2% levobupivacaine (Group B) with 2 Mi g/ml fentanyl as epidural infusion for postoperative pain relief over 24 hours. Pain score, motor blockade, hemodynamic parameters and the need for rescue analgesia were recorded.

RESULTS

Group B patients had significant lower pain score at 4 and 8 hours post operation. There was no significant difference in degree of motor blockade and need for rescue analgesia in both groups. However, patients from Group B had significant hypotension (24% vs 4%) that responded to volume resuscitation without life-threatening complications.

CONCLUSION

0.2% levobupivacaine with 2 Mi g/ml fentanyl provided more superior analgesia compared to 0.1% levobupivacaine with 2 Mi g/ ml fentanyl in patients who underwent lower limb orthopaedic surgery, but with a significant higher incidence of hypotension that responded to volume replacement.

Influence of embedding Cu nano-particles into a Cu/SiO2/Pt structure on its resistive switching

Cu nano-particles (Cu-NPs) were embedded into the SiO2 layer of a Cu/SiO2/Pt structure to examine their influence on resistive switching characteristics. The device showed a reversible resistive switching behavior, which was due to the formation and rupture of a Cu-conducting filament with an electrochemical reaction. The Cu-NPs enhanced the local electric field within the SiO2 layer, which caused a decrease in the forming voltage. During successive switching processes, the Cu-NP was partially dissolved, which changed its shape. Therefore, the switching voltages were not reduced. Moreover, the Cu-NPs caused a non-uniform Cu concentration within the SiO2 layer; thus, the Cu-conducting filament should be formed in a high Cu concentration region, which improves switching dispersion. The Cu-NPs within the SiO2 layer stabilize the resistive switching, resulting in a larger switching window and better endurance characteristics.

Azimuthal reorientation of pentacene upon 2D condensation

We report a novel two-dimensional gas-solid phase transition of pentacene molecules on the Cu(110)-(2 × 1)O surface where the 2D condensation is accompanied by a reversible azimuthal rotation of the pentacene molecules. The change of the optical anisotropy associated with this reorientation allows us to explore the 2D condensation as a function of coverage and temperature by reflectance difference spectroscopy. As a result, the 2D heat of condensation of pentacene on Cu(110)-(2 × 1)O is determined to be 84 meV, which is more than one order of magnitude smaller than the respective value for 3D crystallization.

A novel vertical fan-out platform based on an array of curved anodic alumina nanochannels

Focused ion beam lithography and a two-step anodization have been combined to fabricate a vertical fan-out platform containing an array of unique probes. Each probe comprises three anodic alumina nanochannels with a fan-out arrangement. The lithography is used to pattern an aluminum sheet with a custom-designed array of triangular 'cells' whose apexes are composed of nanoholes. The nanoholes grow into straight nanochannels under proper voltage in the first-step anodization. The second step uses a doubled voltage to induce lateral repulsion among the nanochannels' growth fronts originating in the same cell. Therefore, the fronts fan out. The repulsion roots in the inter-front distance being shorter than the naturally favoured length, which increases with anodization voltage. The fan-out evolution continues until the growth fronts originating in all the cells evolve into a close-packed two-dimensional hexagonal lattice whose spacing is identical to the favoured one. The chemical and physical mechanisms behind the fan-out fabrication are discussed. This novel fan-out platform facilitates probing and handling of many signals from different areas on a sample's surface and is therefore promising for applications in detection and manipulation at the nanoscale level.

Sonographic demonstration of human small intestinal migrating motor complex phase III

BACKGROUND

Migrating motor complex phase III (MMC phase III) of intestine is an important physiological mechanism traditionally recognized by myoelectric recordings or pressure tracings. Direct imaging is difficult and sonographic visualization in human has not been reported.

METHODS

We have demonstrated this unique phenomenon in three patients who underwent abdominal sonographic examinations. Characteristic images were recorded by videotape and both spatial and temporal features were analyzed.

KEY RESULTS

Occurrences of multiple equally spaced, rhythmic intestinal contractions were observed. Parameters including wave frequency, propagation velocity, and duration of the events agreed with those of the well-known phase III. The presence of distinct cyclic patterns observed in two and abolition by meal in the other patient further support our conclusion.

CONCLUSIONS & INFERENCES

We conclude that the migrating waves observed in our study represent the human MMC phase III. This unique finding in human subjects merits further investigation.

Decoupling free-carriers contributions from oxygen-vacancy and cation-substitution in extrinsic conducting oxides

The intrinsic oxygen-vacancies and the extrinsic dopants are two major fundamental free-carrier sources for the extrinsic conducting oxides, such as Sn-doped In(2)O(3). Yet, the individual contributions of the above two free-carrier sources to the total carrier concentrations have never been unraveled. A carrier-concentration separation model is derived in this work, which can define the individual contributions to the total carrier concentration from the intrinsic oxygen-vacancies and the extrinsic dopants, separately. The individual contributions obtained from the present carrier-concentration separation model are verified by the two-state trapping model, photoluminescence, and positron annihilation lifetime (PAL) spectroscopy. In addition, the oxygen-vacancy formation energy of the Sn:In(2)O(3) thin film is determined to be 0.25 eV by PAL spectroscopy.

Observation of two new N* resonances in the decay ψ(3686)→ppπ0

Based on 106×10(6)ψ(3686) events collected with the BESIII detector at the BEPCII facility, a partial wave analysis of ψ(3686)→ppπ0 is performed. The branching fraction of this channel has been determined to be B(ψ(3686)→ppπ0)=(1.65±0.03±0.15)×10(-4). In this decay, 7 N* intermediate resonances are observed. Among these, two new resonances, N(2300) and N(2570) are significant, one 1/2+ resonance with a mass of 2300(-30-0)(+40+109)  MeV/c2 and width of 340(-30-58)(+30+110)  MeV/c2, and one 5/2- resonance with a mass of 2570(-10-10)(+19+34)  MeV/c2 and width of 250(-24-21)(+14+69)  MeV/c2. For the remaining 5 N* intermediate resonances [N(1440), N(1520), N(1535), N(1650) and N(1720)], the analysis yields mass and width values that are consistent with those from established resonances.

Social behaviour risk factors for drug resistant tuberculosis in mainland China: a meta-analysis

OBJECTIVE

To determine risk factors associated with drug resistant tuberculosis (TB) in mainland China.

METHODS

PubMed and Chinese BioMedical databases were searched. Cohort, case-control and cross-sectional studies providing effect estimates of risk factors for any-drug resistant or multidrug resistant (MDR) TB were included.

RESULTS

The meta-analysis included 16 studies. Any-drug resistant TB was significantly associated with poor quality directly observed treatment, shortcourse (DOTS) (odds ratio [OR] 2.65, 95% confidence interval [CI] 1.22, 5.79), long term illness > 1 year (OR 2.71, 95% CI 1.34, 5.48), poor treatment adherence (OR 2.00, 95% CI 1.17, 3.40), previous treatment (OR 4.54, 95% CI 2.71, 7.61) and age 40 - 60 years (OR 1.62, 95% CI 1.10, 2.38). MDR-TB was significantly associated with poor quality DOTS (OR 1.84, 95% CI 1.36, 2.49), poor treatment adherence (OR 4.39, 95% CI 2.97, 6.50), previous treatment (OR 3.83, 95% CI 2.12, 6.89) and poverty (OR 1.87, 95% CI 1.38, 2.52).

CONCLUSIONS

Previous treatment, poor quality DOTS, poor treatment adherence, long term illness, age 40 - 60 years and poverty are associated with a greater risk of drug resistant TB in mainland China.

Layer-dependent morphologies of silver on n-layer graphene

The distributions of sizes of silver nanoparticles that were deposited on monolayer, bilayer, and trilayer graphene films were observed. Deposition was carried out by thermal evaporation and the graphene films, placed on SiO2/Si substrates, were obtained by the mechanical splitting of graphite. Before the deposition, optical microscopy and Raman spectroscopy were utilized to identify the number of the graphene layers. After the deposition, scanning electron microscopy was used to observe the morphologies of the particles. Systematic analysis revealed that the average sizes of the nanoparticles increased with the number of graphene layers. The density of nanoparticles decreased as the number of graphene layers increased, revealing a large variation in the surface diffusion strength of nanoparticles on the different substrates. The mechanisms of formation of these layer-dependent morphologies of silver on n-layer graphene are related to the surface free energy and surface diffusion of the n-layer graphene. The effect of the substrate such as SiO2/Si was investigated by fabricating suspended graphene, and the size and density were similar to those of supported graphene. Based on a comparison of the results, the different morphologies of the silver nanoparticles on different graphene layers were theorized to be caused only by the variation of the diffusion barriers with the number of layers of graphene.

Evidence for the direct two-photon transition from ψ(3686) to J/ψ

The two-photon transition ψ(3686)→γγJ/ψ is studied in a sample of 1.06×10(8) ψ(3686) decays collected by the BESIII detector. The branching fraction is measured to be (3.1±0.6(stat)(-1.0)(+0.8)(syst))×10(-4) using J/ψ→e(+)e(-) and J/ψ→μ(+)μ(-) decays, and its upper limit is estimated to be 4.5×10(-4) at the 90% confidence level. This work represents the first measurement of a two-photon transition among charmonium states. The orientation of the ψ(3686) decay plane and the J/ψ polarization in this decay are also studied. In addition, the product branching fractions of sequential E1 transitions ψ(3686)→γχ(cJ) and χ(cJ)→γJ/ψ(J=0,1,2) are reported.

Electromagnetic scanning to estimate carcass lean content of Taiwan native broilers

To estimate lean content of Taiwan native broiler carcasses accurately, objectively and rapidly, electrical conductivity measurements of broiler carcasses and other relative factors (carcass weight, length and temperature) were used in multiple linear regression analysis for lean prediction. Forty native broiler carcasses, with average market weight 2477.5±465.5 g, were scanned through a 10 MHz electromagnetic field created by an electromagnetic scanner (SA-3203) to measure the total body electrical conductivity (TOBEC) index. After scanning, each broiler carcass was separated into wing, breast, leg and back. Each primal cut was dissected into lean, fat and bone. The weight, length, temperature and TOBEC index of broiler carcass were significantly correlated with lean weight of broiler carcass (P<0.001). Regression analysis for lean estimation with carcass weight, length, temperature and TOBEC index showed higher coefficient of determination (R(2)=0.968) and lower coefficient of variation (CV=4.178) with an equation using beheaded carcass weight, temperature and TOBEC index as variables.

Observation of strain effect on the suspended graphene by polarized Raman spectroscopy

We report the strain effect of suspended graphene prepared by micromechanical method. Under a fixed measurement orientation of scattered light, the position of the 2D peaks changes with incident polarization directions. This phenomenon is explained by a proposed mode in which the peak is effectively contributed by an unstrained and two uniaxial-strained sub-areas. The two axes are tensile strain. Compared to the unstrained sub-mode frequency of 2,672 cm-1, the tension causes a red shift. The 2D peak variation originates in that the three effective sub-modes correlate with the light polarization through different relations. We develop a method to quantitatively analyze the positions, intensities, and polarization dependences of the three sub-peaks. The analysis reflects the local strain, which changes with detected area of the graphene film. The measurement can be extended to detect the strain distribution of the film and, thus, is a promising technology on graphene characterization.

Effects of plasmonic coupling and electrical current on persistent photoconductivity of single-layer graphene on pristine and silver-nanoparticle-coated SiO2/Si

Effects and mechanisms of conductivity variation of chemically vapor deposited single-layer graphene covering silver nanoparticles on SiO(2)/Si are reported based on blue-light (405 nm) induced plasmonic coupling and electrical current induced annealing and desorption of surface adsorbates. With 1V applied voltage, photoconductivity is positive except a brief negative period when the graphene is first illuminated by light. At 10 mV applied voltage, negative photoconductivity persists for hours. In comparison, negative photoconductivity of graphene on pristine SiO(2)/Si persists for tens of hours. When the applied voltage is increased to 1V, it takes tens of hours of light illumination to change to positive photoconductivity.

Prediction consistency and clinical presentations of breast cancer molecular subtypes for Han Chinese population

Background

Breast cancer is a heterogeneous disease in terms of transcriptional aberrations; moreover, microarray gene expression profiles had defined 5 molecular subtypes based on certain intrinsic genes. This study aimed to evaluate the prediction consistency of breast cancer molecular subtypes from 3 distinct intrinsic gene sets (Sørlie 500, Hu 306 and PAM50) as well as clinical presentations of each molecualr subtype in Han Chinese population.

Methods

In all, 169 breast cancer samples (44 from Taiwan and 125 from China) of Han Chinese population were gathered, and the gene expression features corresponding to 3 distinct intrinsic gene sets (Sørlie 500, Hu 306 and PAM50) were retrieved for molecular subtype prediction.

Results

For Sørlie 500 and Hu 306 intrinsic gene set, mean-centring of genes and distance-weighted discrimination (DWD) remarkably reduced the number of unclassified cases. Regarding pairwise agreement, the highest predictive consistency was found between Hu 306 and PAM50. In all, 150 and 126 samples were assigned into identical subtypes by both Hu 306 and PAM50 genes, under mean-centring and DWD. Luminal B tended to show a higher nuclear grade and have more HER2 over-expression status than luminal A did. No basal-like breast tumours were ER positive, and most HER2-enriched breast tumours showed HER2 over-expression, whereas, only two-thirds of ER negativity/HER2 over-expression tumros were predicted as HER2-enriched molecular subtype. For 44 Taiwanese breast cancers with survival data, a better prognosis of luminal A than luminal B subtype in ER-postive breast cancers and a better prognosis of basal-like than HER2-enriched subtype in ER-negative breast cancers was observed.

Conclusions

We suggest that the intrinsic signature Hu 306 or PAM50 be used for breast cancers in the Han Chinese population during molecular subtyping. For the prognostic value and decision making based on intrinsic subtypes, further prospective study with longer survival data is needed.

Reliability and Effectiveness of GEWF Solution in the Identification of Lymph Nodes in Specimens of Colorectal Carcinoma

Lymph node status is pivotal in the staging process of cancer. With regards to colorectal cancer, lymph node retrieval is always laborious. Sometimes, it is also a challenge to recover a minimum of 12 lymph nodes from the pericolorectal tissue. Among many proposed adjunctive solutions, GEWF solution (glacial acetic acid, ethanol, distilled water, and formaldehyde) has been introduced recently and suggested to be superior. To further evaluate its efficiency, the pericolorectal tissue, which has been reexamined extensively in the conventional condition, was refixed into GEWF solution in this study. More lymph nodes were found in 75% (n = 6) of the 8 experimental cases, and 50% (n = 4) of them had 12 or more yielded lymph nodes eventually. In addition, no adverse influences on the expressions of immunohistochemical and special stains were seen. These data support the reliability and effectiveness of GEWF solution in improvement of lymph node yield.

Metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)pyridine produces antidepressant effects in rats: role of brain-derived neurotrophic factor

Recent studies highlight that the brain glutamate system is involved in the etiology of depression and glutamatergic-targeting drugs are currently being explored as novel antidepressant medications. Previous studies reveal that the selective metabotropic glutamate receptor 5 antagonist 2-methyl-6-(phenylethynyl)pyridine (MPEP) produces antidepressant-like effects in behavioral despair and olfactory bulbectomy models. The current study aimed to further explore its behavioral actions in additional animal models of depression (forced swimming test (FST) and learned helplessness (LH) test) and its underlying neurobiological mechanisms. The results demonstrated that acute treatment of MPEP at 30 but not 10mg/kg significantly reduced immobility in FST without affecting locomotor activities. Sub-chronic, five-day treatment of MPEP (30 mg/kg) decreased escape failures in animals that had developed LH symptoms. This sub-chronic treatment also increased hippocampal brain-derived neurotrophic factor (BDNF) protein levels in both non-stressed and stressed animals and restored the stress-induced down-regulation of BDNF expression. Current findings provide strong evidence for further studies of MPEP as a tool to explore novel antidepressants.

First observation of the M1 transition ψ(3686)→γη(c)(2S)

Using a sample of 106×10(6) ψ(3686) events collected with the BESIII detector at the BEPCII storage ring, we have made the first measurement of the M1 transition between the radially excited charmonium S-wave spin-triplet and the radially excited S-wave spin-singlet states: ψ(3686)→γη(c)(2S). Analyses of the processes ψ(3686)→γη(c)(2S) with η(c)(2S)→K(S)(0)K(±)π(∓) and K(+)K(-)π(0) give an η(c)(2S) signal with a statistical significance of greater than 10 standard deviations under a wide range of assumptions about the signal and background properties. The data are used to obtain measurements of the η(c)(2S) mass (M(η(c)(2S))=3637.6±2.9(stat)±1.6(syst) MeV/c(2)), width (Γ(η(c)(2S))=16.9±6.4(stat)±4.8(syst) MeV), and the product branching-fraction (B(ψ(3686)→γη(c)(2S))×B(η(c)(2S)→KKπ)=(1.30±0.20(stat)±0.30(syst))×10(-5)). Combining our result with a BABAR measurement of B(η(c)(2S)→KKπ), we find the branching fraction of the M1 transition to be B(ψ(3686)→γη(c)(2S))=(6.8±1.1(stat)±4.5(syst))×10(-4).