[The feasibility analysis of multi-slice spiral CT features of gastric stromal tumors in predicting pathological National Institutes of Health risk classification].

Objective: To investigate the feasibility of multi-slice spiral CT(MSCT) imaging features of gastric stromal tumor (GST) in predicting pathological NIH risk classification, providing imaging basis for patients with GST before treatment. Methods: The clinical and CT imaging data of 504 patients(506 GST lesions), 259males and 245 females, aged from 13 to 85(60±11) years, with GST confirmed by surgery and pathology collected in the Zhongshan Hospital Affiliated to Fudan University and the Affiliated TCM Hospital of Southwest Medical University. According to pathological NIH risk classification, 506 lesions were divided into low risk group (very low and low risk degree, 277 lesions) and high risk group (medium and high risk degree, 229 lesions).Clinical data and imaging characteristics were compared between two groups. Multivariate logistic regression analysis was performed to screen out independent risk factors for statistically significant imaging indicators. Receiver operating curve (ROC) was used to evaluate the predictive value of tumor length for risk classification. Resulst: Between low risk group and high risk group,there were significant differences in gender(male/female:131/146 vs 129/100), gastrointestinal bleeding(present/absent:39/238 vs 59/170), morphology(regular/Irregular:218/59 vs 95/134), calcification(present/absent:36/241 vs 53/176), degree of necrosis(0°/Ⅰ°/Ⅱ°/Ⅲ°:197/61/16/3 vs 58/98/32/41), ulceration(present/absent:32/245 vs 94/135), growth pattern(endophytic/exophytic/mixed:102/105/70 vs 44/98/87), tumor location(fundus/cardia/body/angle/antrum:98/7/135/12/25 vs 98/6/114/5/6), feeding artery(present/absent:32/245 vs 104/125), vascular enhancement(present/absent:19/258 vs 88/141), effusion of around the disease(present/absent:0/277 vs 13/216), positive sign of fat around the disease(present/absent:0/277 vs 30/199),maximum long diameter[2.82(2.04,3.80) cm vs 5.93(4.06,8.29) cm] and short diameter [2.31(1.60,2.88) cm vs 4.40(3.21,6.37) cm]of tumor(all P<0.05).The maximum long diameter of tumor (OR=2.08,95%CI:1.35-3.20) and ulceration positive(OR=2.01,95%CI:1.03-3.92) were independent risk factors of risk classification(all P<0.05).Gastric antrum was used as the reference for tumor location, gastric fundus(OR=7.77,95%CI:2.00-30.24) and gastric body(OR=3.93,95%CI:1.03-15.01) were independent risk factors of risk classification(all P<0.05).The area under curve(AUC) of the maximum long diameter of tumor for predicting risk classification was 0.87, and the optimal critical value, sensitivity and specificity were 4.98cm, 62.9% and 95.3% respectively. Conclusions: MSCT image features of GST had certain characteristics. MSCT has certain predictive value for pathological NIH risk classification of GST, which can provide certain imaging basis for patients before treatment.

Berlin heart ventricular assist device as a long-term bridge to transplantation in a Fontan patient with failing single ventricle.

The use of VADs as a BTT in children with heart failure has increased due to enhanced device design and reliability, leading to improved survival, functional capacity, and quality of life. However, the use of VADs in patients with Fontan physiology as a BTT is rare with few case reports. Here, we describe a case of implantation of the Berlin VAD as a BTT for 179 days, one of the longest reported periods of mechanical support, in a child with failing single ventricle.

Spin caloritronics of blue phosphorene nanoribbons.

We report a first-principles study of the magnetic properties and spin caloritronics of zigzag-type blue phosphorene nanoribbons (zBPNRs). It is found that the bare zBPNR (0H-zBPNR) or monohydrogenated zBPNR (1H-zBPNR) exhibit spin-semiconducting properties arising from the edge electronic states. We further confirm that the py orbitals of the edge P atoms have the main contributions to these states. The spin-semiconducting property has a natural advantage for fabricating perfect thermospin devices with a stronger spin Seebeck effect than charge Seebeck effect at the Fermi level. When a temperature difference is applied, the electric current with the different spin index displays a bipolar behavior, and the spin-filtering efficiency can reach 1200%. By changing the widths of 0H-zBPNR and 1H-zBPNR, the ratio of the spin Seebeck coefficient to the charge Seebeck coefficient at the Fermi level is about 10 at room temperature.

Indirect-direct band gap transition through electric tuning in bilayer MoS2.

We investigate the electronic properties of bilayer MoS2 exposed to an external electric field by using first-principles calculations. It is found that a larger interlayer distance, referring to that by standard density functional theory (DFT) with respect to that by DFT with empirical dispersion corrections, makes indirect-direct band gap transition possible by electric control. We show that external electric field effectively manipulates the valence band contrast between the K- and Γ-valleys by forming built-in electric dipole fields, which realizes an indirect-direct transition before a semiconductor-metal transition happens. Our results provide a novel efficient access to tune the electronic properties of two-dimensional layered materials.

Intrinsic ferromagnetism in hexagonal boron nitride nanosheets.

Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

Ligature-Induced Periodontitis Drives Colorectal Cancer: An Experimental Model in Mice.

Periodontitis is a prevalent inflammatory oral disease associated with an increased risk of colorectal cancer. Experimental animal models are critical tools to investigate the effects and mechanisms of periodontitis on colorectal cancer. Several murine periodontitis models have been used in research, including oral gavage, periodontal pathogen injection, and ligature models. The role of experimental periodontitis caused by silk ligation in colorectal cancer remains unclear. In this study, we used an experimental periodontitis model on a colitis-associated colorectal cancer model and a spontaneous model, respectively. We observed the promotion of colorectal cancer in ligature-induced periodontitis mice compared to those control mice in 2 different models, as assessed by tumor number, tumor size, and tumor load. Since bacterial dysbiosis is an important feature of periodontitis, we next analyzed the oral and gut microbiomes using 16S ribosomal RNA gene sequencing. We found that the experimental periodontitis model reshaped the microbial community in the oral cavity and gut. In addition, we found a higher extent of programmed death 1 (PD-1)-positive CD8+ T-cell infiltration in tumor samples of the periodontitis group than in controls by immunofluorescence staining. Regarding the potential molecular mechanism, we transplanted the fecal microbiota of the periodontitis patient into mice and observed a tumor-promoting effect in the periodontitis group, assessed by tumor volume and tumor weight, together with a low level of INF-γ+ CD8+ T-cell infiltration in subcutaneous tumor mice. Taken together, we show that ligature-induced periodontitis model promotes colorectal cancer by microbiota remodeling and suppression of the immune response.

Generating high-order optical and spin harmonics from ferromagnetic monolayers.

High-order harmonic generation (HHG) in solids has entered a new phase of intensive research, with envisioned band-structure mapping on an ultrashort time scale. This partly benefits from a flurry of new HHG materials discovered, but so far has missed an important group. HHG in magnetic materials should have profound impact on future magnetic storage technology advances. Here we introduce and demonstrate HHG in ferromagnetic monolayers. We find that HHG carries spin information and sensitively depends on the relativistic spin-orbit coupling; and if they are dispersed into the crystal momentum k space, harmonics originating from real transitions can be k-resolved and carry the band structure information. Geometrically, the HHG signal is sensitive to spatial orientations of monolayers. Different from the optical counterpart, the spin HHG, though probably weak, only appears at even orders, a consequence of SU(2) symmetry. Our findings open an unexplored frontier-magneto-high-order harmonic generation.

Magnetic spin moment reduction in photoexcited ferromagnets through exchange interaction quenching: beyond the rigid band approximation.

The exchange interaction among electrons is one of the most fundamental quantum mechanical interactions in nature and underlies any magnetic phenomena from ferromagnetic ordering to magnetic storage. The current technology is built upon a thermal or magnetic field, but a frontier is emerging to directly control magnetism using ultrashort laser pulses. However, little is known about the fate of the exchange interaction. Here we report unambiguously that photoexcitation is capable of quenching the exchange interaction in all three 3d ferromagnetic metals. The entire process starts with a small number of photoexcited electrons which build up a new and self-destructive potential that collapses the system into a new state with a reduced exchange splitting. The spin moment reduction follows a Bloch-like law as M(z)(ΔE) = M(z)(0)(1 - ΔE/ΔE0)(1/ß), where ΔE is the absorbed photon energy and ß is a scaling exponent. A good agreement is found between the experimental and our theoretical results. Our findings may have a broader implication for dynamic electron correlation effects in laser-excited iron-based superconductors, iron borate, rare-earth orthoferrites, hematites and rare-earth transition metal alloys.

Temperature-Dependent Asymmetry of Anisotropic Magnetoresistance in Silicon p-n Junctions.

We report a large but asymmetric magnetoresistance in silicon p-n junctions, which contrasts with the fact of magnetoresistance being symmetric in magnetic metals and semiconductors. With temperature decreasing from 293 K to 100 K, the magnetoresistance sharply increases from 50% to 150% under a magnetic field of 2 T. At the same time, an asymmetric magnetoresistance, which manifests itself as a magnetoresistance voltage offset with respect to the sign of magnetic field, occurs and linearly increases with magnetoresistance. More interestingly, in contrast with other materials, the lineshape of anisotropic magnetoresistance in silicon p-n junctions significantly depends on temperature. As temperature decreases from 293 K to 100 K, the width of peak shrinks from 90° to 70°. We ascribe these novel magnetoresistance to the asymmetric geometry of the space charge region in p-n junction induced by the magnetic field. In the vicinity of the space charge region the current paths are deflected, contributing the Hall field to the asymmetric magnetoresistance. Therefore, the observed temperature-dependent asymmetry of magnetoresistance is proved to be a direct consequence of the spatial configuration evolution of space charge region with temperature.

XeCl laser surgery of the vocal cords: a histologic comparison with CO2 laser in a porcine model.

Fresh cadaveric pig larynxes were ablated with a CO2 (lambda = 10.6 microm) and a XeCl excimer (lambda = 308 nm) laser. Histologic comparison of the ablation craters created by the two lasers was performed, and ablation crater depth and marginal tissue damage were measured. Crater depth for both laser treatments is correlated with energy deposition and exposure time. The CO2 laser creates three times more nonspecific, marginal tissue damage than the XeCl laser at the ranges of total energy and exposure times used. This study demonstrates the potential of the XeCl laser as an alternative to the CO2 laser in microlaryngeal surgery.

Crystal-momentum dispersion of ultrafast spin change in fcc Co.

Nearly twenty years ago, Beaurepaire and coworkers showed that when an ultrafast laser impinges on a ferromagnet, its spin moment undergoes a dramatic change, but how it works remains a mystery. While the current experiment is still unable to resolve the minute details of the spin change, crystal momentum-resolved techniques have long been used to analyze the charge dynamics in superconductors and strongly correlated materials. Here we extend it to probe spin moment change in the entire three-dimensional Brillouin zone for fcc Co. Our results indeed show a strong spin activity along the Δ line, supporting a prior experimental finding. The spin active pockets coalesce into a series of spin surfaces that follow the Fermi surfaces. We predict two largest spin change pockets which have been elusive to experiments: one pocket is slightly below the Δ line and the other is along the Λ line and close to the L point. Our theory presents an opportunity for the time-, spin- and momentum-resolve photoemission technique.

Theoretical Prediction of Carrier Mobility in Few-Layer BC2N.

An ideal semiconducting material should simultaneously hold a considerable direct band gap and a high carrier mobility. A 2D planar compound consisting of zigzag chains of C-C and B-N atoms, denoted as BC2N, would be a good candidate. It has a direct band gap of 2 eV, which can be further tuned by changing the layer number. At the same time, our first-principles calculations show that few-layer BC2N possesses a high carrier mobility. The carrier mobility of around one million sqaure centimeters per volt-second is obtained at its three-layer. As our study demonstrated, few-layer BC2N has potential applications in nanoelectronics and optoelectronics.

Resolving photon-shortage mystery in femtosecond magnetism.

For nearly a decade, it has been a mystery why the small average number of photons absorbed per atom from an ultrashort laser pulse is able to induce a strong magnetization within a few hundred femtoseconds. Here we resolve this mystery by directly computing the number of photons per atom layer by layer as the light wave propagates inside the sample. We find that for all the 24 experiments considered here, each atom has more than one photon. The so-called photon shortage does not exist. By plotting the relative demagnetization change versus the number of photons absorbed per atom, we show that, depending on the experimental condition, 0.1 photon can induce about 4%-72% spin moment change. Our perturbation theory reveals that the demagnetization depends linearly on the amplitude of the laser field. In addition, we find that the transition frequency of a sample may also play a role in magnetization processes. As long as the intensity is not zero, the intensity of the laser field only affects the matching range of the transition frequencies, but not whether the demagnetization can happen or not.

Dynamic heat capacity changes of laser-irradiated type I collagen films.

BACKGROUND AND OBJECTIVE: A common assumption made in the thermal response of biological materials due to laser irradiation is the constancy of the specific heat capacity at constant pressure, CP. In this investigation, CP of pure hydrated Type I collagen films is measured in time during laser irradiation. STUDY DESIGN/MATERIALS AND METHODS: A Nd:YAG laser scanning calorimeter is developed and used to test the constant heat capacity assumption by monitoring transient, laser-induced thermal transitions in the collagen films. RESULTS: Results of preliminary studies on the irreversible, laser induced thermal denaturation of collagen with heating rates of up to 110 K/sec show a broad CP transition that can attain large values (20 J/g K). CONCLUSION: The magnitude of the CP change that occurs in response to laser irradiation shows that the assumption of a constant CP when modeling heat transport in tissues is not always valid.

Perillyl alcohol inhibits TCR-mediated [Ca(2+)](i) signaling, alters cell shape and motility, and induces apoptosis in T lymphocytes.

Perillyl alcohol (POH) inhibits isoprenylation and has shown anticancer and chemopreventive properties in rodent models. The mechanism that underlies the anticancer activity of POH and other isoprenylation inhibitors is unknown but has been postulated to involve decreased levels of isoprenylated Ras and Ras-related proteins. Previously we demonstrated that POH effectively inhibits human T cell proliferation in vitro and can prevent acute and chronic rejection in a rat cardiac transplant model. In this report, we investigate the effects of POH on T lymphocytes at the single-cell level. POH disrupts the polarized shape and motility of antigen-specific murine 1E5 T cells. Using an optical trap to position anti-CD3-coated beads in contact with 1E5 T cells, we demonstrate that POH inhibits their TCR-mediated calcium response. Furthermore, we show that POH preferentially induces apoptosis in PHA-activated human T cells as well as in 1E5 T cells.