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Artificial synapses in neuromorphic computing systems hold potential to emulate biological synaptic plasticity to achieve brain-like computation and autonomous learning behaviors in non-von-Neumann systems. 2D materials, such as graphene, graphene oxide, hexagonal boron nitride, transition metal dichalcogenides, transition metal oxides, 2D perovskite, and black phosphorous, have been explored to achieve many functionalities of biological synapses due to their unique electronic, optoelectronic, electrochemical, and mechanical properties that are lacking in bulk materials. This review features the current development in the state-of-the-art artificial synaptic electronic devices based on 2D materials. The structures of these devices are first discussed according to their number of terminals (two-, three-, four-, and multi-terminals) and geometric layouts (vertical, horizontal, hybrid). Since different 2D materials have been utilized to fabricate these devices, their underlying physical mechanisms and principles are further discussed, and their artificial neuron synaptic functionalities and performances are analyzed and contrasted. Finally, a summary of the current research status and major achievements is concluded, and the outlooks and perspectives for this emerging and vibrant field and the potential applications of these devices for neuromorphic computing are presented.

Interfaces are essential elements in nanoscale devices and their properties can differ significantly from their bulk counterparts. Because interfaces often act as bottlenecks in heat dissipation, the prediction and control of the interfacial thermal conductance is critical to the design of nanoscale devices. In this review, we examine the recent advances in quantum interfacial thermal transport from a theoretical and computational perspective. We discuss in detail recent advances in the Atomistic Green's Function method which is an important tool for predicting interfacial thermal transport. We also discuss recent progress in the understanding of interfacial transport mechanisms, including the role of interfacial modes, the role of anharmonic phonon-phonon coupling, the role of electron-phonon interaction, and the ways to tune the interfacial thermal conductance. Finally, we give an overview of the challenges and opportunities in this research field.

We investigate the anharmonic phonon scattering across a weakly interacting interface by developing a quantum mechanics-based theory. We find that the contribution from anharmonic three-phonon scatterings to interfacial thermal conductance can be cast into Landauer formula with transmission function being temperature-dependent. Surprisingly, in the weak coupling limit, the transmission due to anharmonic phonon scattering is unbounded with increasing temperature, which is physically impossible for two-phonon processes. We further reveal that the anharmonic contribution in a real heterogeneous interface (e.g., between graphene and monolayer molybdenum disulfide) can dominate over the harmonic process even at room temperature, highlighting the important role of anharmonicity in weakly interacting heterogeneous systems.

Using DFT calculations, we investigate the effects of the type, location, and density of point defects in monolayer MoS2 on electronic structures and Schottky barrier heights (SBH) of Au/MoS2 heterojunction. Three types of point defects in monolayer MoS2, that is, S monovacancy, S divacancy and MoS (Mo substitution at S site) antisite defects, are considered. The following findings are revealed: (1) The SBH for the monolayer MoS2 with defects is universally higher than that for its defect-free counterpart. (2) S divacancy and MoS antisite defects increase the SBH to a larger extent than S monovacancy. (3) A defect located in the inner sublayer of MoS2, which is adjacent to Au substrate, increases the SBH to a larger extent than that in the outer sublayer of MoS2. (4) An increase in defect density increases the SBH. These findings indicate a large variation of SBH with the defect type, location, and concentration. We also compare our results with previously experimentally measured SBH for Au/MoS2 contact and postulate possible reasons for the large differences among existing experimental measurements and between experimental measurements and theoretical predictions. The findings and insights revealed here may provide practice guidelines for modulation and optimization of SBH in Au/MoS2 and similar heterojunctions via defect engineering., Comment: 20 pages, 8 figures

A remarkable recent advancement has been the successful synthesis of two-dimensional boron monolayers on metal substrates. However, although up to 16 possible bulk allotropes of boron have been reported, none of them possess van der Waals (vdW) layered structures. In this work, starting from the experimentally synthesized monolayer boron sheet (β12 borophene), we explored the possibility for forming vdW layered bulk boron. We found that two β12 borophene sheets cannot form a stable vdW bilayer structure, as covalent-like B–B bonds are formed between them because of the peculiar bonding. Interestingly, when the covalently bonded bilayer borophene sheets are stacked on top of each other, three-dimensional (3D) layered structures are constructed via vdW interlayer interactions, rather than covalent. The 3D vdW layered structures were found to be dynamically stable. The interlayer binding energy is about 20 meV/Å2, which is close to the weakly bound graphene layers in graphite (∼16 meV/Å2). Furthermore, the density functional theory predicted electronic band structure testifies that these vdW bulk boron crystals can behave as good conductors. The insights obtained from this work suggest an opportunity to discover new vdW layered structures of bulk boron, which is expected to be crucial to numerous applications ranging from microelectronic devices to energy storage devices.

Heat energy in solids is carried by phonons and electrons. However, in most two-dimensional (2D) materials, the contribution from electrons to total thermal conduction is much lower than that for phonons. In this work, through first-principles calculations combined with non-equilibrium Green’s function theory, we studied electron and phonon thermal conductance in recently synthesized 2D hydrogen boride. The hexagonal boron network with bridging hydrogen atoms is suggested to exhibit comparable lattice thermal conductance (4.07 nWK−1 nm−2) as graphene (4.1 nWK−1 nm−2), and similar electron thermal conductance (3.6 nWK−1 nm−2), which is almost ten times that of graphene. As a result, total thermal conductance of 2D hydrogen boride is about two-fold of graphene, being the highest value in all known 2D materials. Moreover, tensile strain along the armchair direction leads to an increase in carrier density, significantly increasing electron thermal conductance. The increase in electron thermal conductance offsets the reduction in phonon thermal conductance, contributing to an abnormal increase in thermal conductance. We demonstrate that the high electron density governs extraordinarily high thermal conductance in 2D hydrogen boride, distinctive among 2D materials.

We studied the thermal conductivity of Al-intercalated bilayer δ4 borophene sheet by solving phonon Boltzmann transport equation based on density functional theory. Although the overall atomic dens...

We perform quantum master equation calculations and machine learning to investigate the thermoelectric properties of multiple interacting quantum dots (MQD), including electrical conductance, Seebeck coefficient, thermal conductance and the figure of merit (ZT). We show that by learning from the data obtained from the QME, the thermoelectric states of the MQD can be represented well by a two-layer neural network. We also show that after training, the neural network was able to predict the thermoelectric properties of the MQD with much less computational cost compared to the QME approach. Based on the neural network, we further optimize the MQD to achieve a high ZT and power factor. This work presents a powerful route to study, represent, and optimize interacting quantum many-body systems.

We investigate thermoelectric transport through interfaces with inelastic scatterings by developing a quantum theory, which has been extensively validated by existing theories. We find that under temperature bias, while a two-terminal conductor-insulator interface behaves only as a thermal resistor, a three-terminal conductor-insulator-conductor interface can function as an electricity generator caused by phonon-mediated electron scatterings with heat-charge current separation. Unlike conventional thermoelectrics which is a property of a bulk caused by the Seebeck effect, this thermoelectric behavior is a property of an interface driven by electron-phonon scatterings., Comment: 6 pages, 5 figures

The cubic boron arsenide (BAs) crystal has received extensive research attention because of its ultra-high thermal conductivity comparable to that of diamond. In this work, we performed a comprehensive study on the diffusive thermal properties of its two-dimensional (2D) counterpart, the monolayer honeycomb BAs (h-BAs), through solving the phonon Boltzmann transport equation combined with first-principles calculation. We found that unlike the pronounced contribution from out-of-plane acoustic phonons (ZA) in graphene, the high thermal conductivity (181 W m−1 K−1 at 300 K) of h-BAs is mainly contributed by in-plane phonon modes, instead of the ZA mode. This result is explained by the unique frequency-independent ‘platform’ region in the relaxation time of in-plane phonons. Moreover, we conducted a comparative study of thermal conductivity between 2D h-BAs and h-GaN, because both of them have a similar mass density. The thermal conductivity of h-BAs is one order of magnitude higher than that of h-GaN (16 W m−1 K−1), which is governed by the different phonon scattering process attributed to the opposite wavevector dependence in out-of-plane optical phonons. Our findings provide new insight into the physics of heat conduction in 2D materials, and demonstrate h-BAs to be a new thermally conductive 2D semiconductor.

Semiconducting materials with high thermal conductivity are valuable for thermal management in highly integrated systems, in which heat must be dissipated efficiently. Cubic boron arsenide (BAs) is recently attracting numerous research attention due to its comparable thermal conductivity with diamond. However, thermal conductivity of monolayer honeycomb BAs is much lower than the bulk counterpart. Herein, based on Boltzmann transport equation and non-equilibrium Green’s function calculation, we suggest a new unexplored covalently bonded bi-layer BAs to exhibit high thermal conductivity, which is about two times of that of bulk silicon. Unlike the remarkable reduction in thermal conductivity from monolayer graphene to bi-layer graphene, thermal conductivity of bi-layer BAs is about 70% higher than its monolayer counterpart. Central to this novel behavior was the largely suppressed phonon scattering phase space and anharmonicity. The anomalously high thermal conductivity of the covalently bonded bi-layer BAs and the emergent underlying mechanism discussed here open up space for further manipulation of thermal properties of 2D materials, and facilitate their applications to important problems in nanoscale electronic and optoelectronic devices.

Using first-principles calculations, we investigate the effect of molecular doping and sulfur vacancy on the electronic properties and charge modulation of monolayer MoS2. It is found that tetrathiafulvalene and dimethyl-p-phenylenediamine molecules are effective donors, whereas tetracyanoethylene (TCNE) and tetracyanoquinodimethane (TCNQ) are effective acceptors, and all these molecules are able to shift the work function of MoS2. For MoS2 containing sulfur vacancies, these molecules are able to change the position of the defect levels within the band gap and modulate the carrier density around the defect center. Charge transfer analysis shows that TCNE and TCNQ induce a free-carrier depletion of the defect states, which is beneficial for the suppression of the nonradiative trionic decay and a higher excitonic efficiency due to a decrease in the screening of excitons. Furthermore, the effects of molecular adsorption on Seebeck coefficient of MoS2 are also explored. Our work suggests that an enhanced exci...

Phosphorene is a new-emerging two-dimensional material with many fascinating electronic and thermal properties. Using nonequilibrium Green’s function technique, we investigate the thermoelectric transport properties of phosphorene in the ballistic transport regime. We find that while the electronic conductance and thermal conductance of phosphorene are highly anisotropic, the Seebeck coefficient is isotropic. The maximum predicted thermopower reaches 2500 μV/K. We also find that the Wiedemann–Franz law is valid only when the chemical potential is inside valence band or conduction band. When the chemical potential is near the valence band maximum or conduction band minimum; however, the Wiedemann–Franz law becomes invalid, and interestingly, the figure of merit ZT reaches its maximum value. We also find that figure of merit ZT increases with the increase of temperature, and ZT in the armchair direction is much higher than that in the zigzag direction. By analyzing the various effects on ZT, we discuss the possible routines to enhance figure of merit ZT.

In this work, combining first-principles calculation and the phonon Boltzmann transport equation, we explored the diffusive thermal conductivity of diamond-like bi-layer graphene. The converged iterative solution provides high room temperature thermal conductivity of 2034 W mK-1, significantly higher than other 2D materials. More interesting, the thermal conductivity calculated by relaxation time approximation is about 33% underestimated, revealing a remarkable phonon hydrodynamic transport characteristic. Significant strain dependence is reported, for example, under 5% tensile strain, room temperature thermal conductivity (1081 W mK-1) of only about 50% of the strain-free sample, and under 20% strain, it reduces dramatically to only about 11% of the intrinsic one (226 W mK-1). Unexpectedly, in addition to the remarkable reduction in the absolute value of thermal conductivity, tensile strain can impact the hydrodynamic significance. For example, under 5% strain, the underestimation of relaxation time approximation in thermal conductivity is reduced to 20%. Furthermore, using a non-equilibrium Green's function calculation, high ballistic thermal conductance (2.95 GW m-2 K-1) is demonstrated, and the mean free path is predicted to be 700 nm at room temperature. The importance of the knowledge of phonon transport in diamond-like bi-layer graphene goes beyond fundamental physics owing to its relevance to thermal management applications due to the super-high thermal conduction.

The last decades have seen tremendous progress in quantitative understanding of phonon transport, which is critical for the thermal management of various functional devices and the proper optimization of thermoelectric materials. In this work, using first-principles based calculation combined with non-equilibrium Green's function and phonon Boltzmann transport equation, we provide a systematic study on the phonon stability and phonon transport of monolayer boron sheet with honeycomb, graphene-like structure (graphene-like borophene) in both ballistic and diffusive regimes. For free-standing graphene-like borophene, phonon instabilities occur near the centre of Brillouin zone, implying elastic instability. Investigation of the electronic structures shows that the phonon instability is due to the deficiency of electrons. Our first-principles results show that with net charge doping and in-plane tensile strain, the graphene-like borophene is becoming thermodynamic stable in ideal plat nature, because the bonding characteristic is modified. At room temperature, the ballistic thermal conductance of graphene-like borophene 7.14 nWK-1 nm-2) is higher than that of graphene (4.1 nWK-1 nm-2), due to high phonon transmission. However, its diffusive thermal conductivity is two orders of magnitude lower than graphene, because the phonon relaxation time is dramatically reduced comparing with its carbon counterpart. Although the phonon group velocity and phonon anharmonicity are comparable with that of graphene, the suppressed phonon space results in dramatically strong phonon-phonon scattering. These thermal transport characteristics in both ballistic and diffusive regimes are of fundamental and technological relevance and provide guidance for applications of boron based nanomaterials in which their thermal conduction is major concern.

Monolayer indium selenide (InSe) possesses numerous fascinating properties, such as high electron mobility, quantum Hall effect and anomalous optical response. However, its phonon properties, thermal transport properties and the origin of its structural stability remain unexplored. Using first-principles calculations, we show that the atoms in InSe are highly polarized and such polarization causes strong long-range dipole–dipole interaction (DDI). For acoustic modes, DDI is essential for maintaining its structural stability. For optical modes, DDI causes a significant frequency shift of its out-of-phase vibrations. Surprisingly, we observed that there were two isolated frequency regimes, which were completely separated from other frequency regimes with large frequency gaps. Within each frequency regime, only a single phonon mode exists. We further reveal that InSe possesses the lowest thermal conductance among the known two-dimensional materials due to the low cut-off frequency, low phonon group velocities and the presence of large frequency gaps. These unique behaviors of monolayer InSe can enable the fabrication of novel devices, such as thermoelectric module, single-mode phonon channel and phononic laser.

In the chapter we review various theoretical methods for the evaluation of thermal conduction properties, carried by phonons. In detail, we first demonstrate the methods of calculating thermal conductivity from its near-equilibrium properties, including kinetic theory, Boltzmann transport equation method and the Green–Kubo approach together with equilibrium molecular dynamics. We then illustrate the non-equilibrium methods of calculating thermal currents, including the non-equilibrium molecular dynamics and the non-equilibrium Green's function formalism. For each method, we analyze its respective viewpoint of transport picture, the assumptions made, its strength and weakness in handling transport problem and its applicability in different situations.

Atomic mass and interatomic interaction are the two key quantities that significantly affect the heat conduction carried by phonons. Here, we study the effects of long-range (LR) interatomic interaction and mass-disorder on the phonon transport in a one-dimensional harmonic chain withup to 10^5 atoms. We find that while LR interaction reduces the transmission of low frequency phonons, it enhances the transmission of high frequency phonons by suppressing the localization effects caused by mass disorder. Therefore, long-range interaction is able to boost heat conductance in the high temperature regime or in the large size regime, where the high frequency modes are important.

Curvature induced by mechanical deformation in nanostructures has been found to significantly affect their stability and reliability during applications. In this work, we investigated the effects of curvature induced by mechanical bending on the thermal properties of silicon nanowire (SiNW) by using molecular dynamics simulations. By examining the relationship between the curved geometry and local temperature/heat flux distribution, we found that there is no temperature gradient/heat flux along the radial direction of the bent SiNW, and the local heat current density along the circumferential direction varies with the radius of curvature. Interestingly, a ∼10% reduction in the thermal conductivity is found in the bent SiNW due to the depression of long-wavelength phonons caused by its inhomogeneous deformation. The present work demonstrates that the curvature induced by mechanical bending can be used to modulate the thermal conductivity of SiNWs.Curvature induced by mechanical deformation in nanostructures has been found to significantly affect their stability and reliability during applications. In this work, we investigated the effects of curvature induced by mechanical bending on the thermal properties of silicon nanowire (SiNW) by using molecular dynamics simulations. By examining the relationship between the curved geometry and local temperature/heat flux distribution, we found that there is no temperature gradient/heat flux along the radial direction of the bent SiNW, and the local heat current density along the circumferential direction varies with the radius of curvature. Interestingly, a ∼10% reduction in the thermal conductivity is found in the bent SiNW due to the depression of long-wavelength phonons caused by its inhomogeneous deformation. The present work demonstrates that the curvature induced by mechanical bending can be used to modulate the thermal conductivity of SiNWs.

By way of the non-equilibrium Green's function simulations and analytical expressions, the quantum thermal conductance of stanene is studied. We find that, due to the existence of Dirac fermion in stanene, the ratio of electron thermal conductance and electric conductance becomes a chemical-potential-dependent quantity, violating the Wiedemann-Franz law. This finding is applicable to any two-dimensional (2D) materials that possess massless Dirac fermions. In strong contrast to the negligible electronic contribution in graphene, surprisingly, the electrons and phonons in stanene carry a comparable heat current. The unusual behaviours in stanene widen our knowledge of quantum thermal transport in 2D materials.

For breast cancer patients with lymph node metastasis, paclitaxel is the first-line chemotherapy drug. Clinical studies showed that some patients with breast cancer were insensitive to paclitaxel, which led to chemotherapy failure. Today, no validated markers exist for the prediction of chemotherapy sensitivity in this patient group. Tissue inhibitor of metalloproteinases-1 (TIMP-1) has been shown to protect against apoptosis. Epidemiological studies have also associated elevated tumor tissue TIMP-1 levels with a poor response to cyclophosphamide/methotrexate/5-fluorouracil and anthracycline-based chemotherapy. Additionally, our previous study proved that TIMP-1 significantly decreased the sensitivity of breast cancer cells to paclitaxel-induced apoptosis by enhancing degradation of cyclin B1. These data imply that TIMP-1 may be a useful predictive biomarker for chemotherapy resistance. In this retrospective study, we investigated the association between expression levels of TIMP-1 protein in the primary tumor and objective response to paclitaxel-based chemotherapy in 99 patients with breast cancer. With Kaplan-Meier survival analysis, the patients with high TIMP-1 levels were found to have significantly worse 5-year DFS (71.1 %) than the patients with low levels (88.5 %; P = 0.020). Similarly, the patients with high TIMP-1 levels had significantly worse 5-year OS (78.9 %) than patients with low levels (96.7 %; P = 0.004). In Cox's univariate and multivariate analyses, TIMP-1 was prognostic for both DFS and OS. Our data showed that elevated tumor tissue TIMP-1 levels were significantly associated with a poor response to paclitaxel-based chemotherapy, and TIMP-1 might be a potential biomarker for predicting response of breast cancer patients to paclitaxel-based chemotherapy.

A clear understanding and proper control of interfacial thermal transport is important in nanoscale device. In this review, we first discuss the theoretical methods to handle the interfacial thermal transport problem, such as the macroscopic model, molecular dynamics, lattice dynamics and modern quantum transport theories. Then we discuss various effects that can significantly affect the interfacial thermal transport, such as the formation of chemical bonds at interface, defects and interface roughness, strain and substrates, atomic species and mass ratios, structural orientations. Then importantly, we analyze the role of inelastic scatterings at the interface, and discuss its application in thermal rectifications. Finally, the challenges and promising directions are discussed., Comment: 34 pages, 8 figures, topic review

The topic of this review is the effects of electron-phonon interaction (EPI) on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green's function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system's thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor's atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons., Comment: 22 pages,173 refs., AIP Adv.,Special Topic: Phononics and Thermal Energy Control

The insulin-like growth factor (IGF) axis is a complex system composed of two mitogenic ligands, IGF-I and IGF-II, two receptors, IGF-IR and IGF-IIR, and six binding proteins, IGFBP1 to IGFBP6. The IGFBPs exert their actions through their regulation of IGF bioavailability for IGF receptors. The present study evaluated the correlation between IGFBP2 expression and clinicopathologic parameters and cell proliferation in cancer by using surgically resected tissue specimens from 97 patients with gastric carcinoma treated at our hospital. Immunohistochemical staining was performed using IGFBP2 and Ki-67 monoclonal antibody. An obvious difference existed in the IGFBP2 expression between carcinomas and normal mucosa. Correlation between IGFBP2 expression and the depth of penetration, lymph node metastasis, and clinical stage were observed. There was positive correlation between IGFBP2 expression and Ki-67 expression. We conclude that IGFBP2 may be involved in carcinogenesis and progression of gastric carcinoma by promoting cell proliferation.

We present a comprehensive study of thermoelectric transport properties of a quantum nanoelectromechanical system (NEMS) described by a single-electron-transistor (SET) coupled to a quantum nanomechanical resonator (NR). The effects of a quantum NR on the electronic current are investigated with special emphasis on how the SET-NR coupling strength plays a role in such a NEMS. We find that the SET-NR coupling is not only able to suppress or enhance the thermoelectric current but can also switch its direction. The effect of the NR on the thermoelectric coefficients of the SET are studied and we find that even a small SET-NR coupling could dramatically suppress the figure of merits ZT . Lastly, we investigate the backaction of electronic current on the NR and possible routes of heating or cooling the NR are discussed. We find that by appropriately tuning the gate voltage the backaction can be eliminated, which could find possible applications to enhance the sensitivity of detection devices.

We present a general theory to calculate the steady-state heat and electronic currents for nonlinear systems using a perturbative expansion in the system-bath coupling. We explicitly demonstrate that using the truncated Dyson-series leads to divergences in the steady-state limit, thus making it impossible to be used for actual applications. In order to resolve the divergences we propose a unique choice of initial-condition for the reduced density matrix, which removes the divergences at each order. Our approach not only allows us to use the truncated Dyson-series, with a reasonable choice of initial condition, but also gives the expected result that the steady-state solutions should be independent of initial preparations. Using our improved Dyson series we evaluate the heat and electronic currents upto fourth-order in system-bath coupling, a considerable improvement over the standard quantum master equation techniques. We then numerically corroborate our theory for archetypal settings of linear systems using the exact nonequilibrium Green's function approach. Lastly, to demonstrate the advantage of our approach we deal with the nonlinear spin-boson model to evaluate heat current upto fourth-order and find signatures of cotunnelling process., 14 pages, 5 figures. This version is accepted in the Journal of Chemical Physics

Hypersensitivity to mosquito bite (HMB) is defined as intense skin reactive lesion after mosquito bite. However, some kind of malignant tumor is closely associated with HMB, especially natural killer (NK)/T-cell lymphoma. We described a nasal-type NK/T-cell lymphoma in a 9-year-old girl after a history of 2 years earlier of HMB. Pathologic evaluation revealed the typical histologic features of NK/T-cell lymphoma, and the dermal and subcutaneous inflammatory reaction of HMB lesions. HMB is rarely reported and should be kept in mind as a clinical sign of subsequent NK/T-cell lymphoma in Asian country where HMB is relatively frequently encountered.

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited cancer predisposition syndrome, characterized by development of a variety of neoplasms in multiple organs. Central nervous system hemangioblastoma (CHB) is the most common manifestation of VHL disease. The germline mutations in the VHL tumor suppressor gene are responsible for the inherited cancer predisposition syndrome. To expand the VHL mutation data and to investigate the tumorigenesis of VHL-associated CNS hemangioblastoma, 24 CHB tissue samples and blood samples of 14 patients from 10 Chinese VHL families were collected and subjected to molecular genetic analysis. Six distinctive germline mutations were identified, and the 601 G to C (Val130Phe) mutation is reported for the first time. Somatic mutations analysis of the VHL gene in VHL-associated CHB showed that loss of heterozygosity (LOH) occurred in more than half of the cases. In addition, expression of the ZAC1 tumor suppressor gene protein was studied using immunohistochemistry staining in CHB tissues with a specific polyclonal antibody. The ZAC1 protein was lost in all CHB. Our data exhibited high frequency of LOH of ZAC1 gene in VHL-associated CHB, indicating that ZAC1 may have a role in tumorigenesis of VHL-associated CHB.

Meningiomas are attributed to those tumours with slow-growing pattern occurring predominantly in middle-aged or elderly patients. Fifteen histological variants have been described based on the variable histomorphological features. Herein we report four cases with specific Zellballen growth pattern, giving the tumours a 'paraganglioma-like' general aspect. The diagnosis of meningiomas was confirmed by immunohistochemical and ultrastructural findings. Histopathologists should be aware of this specific morphology which can lead to misdiagnosis.

Metaplastic breast carcinoma (MBC) encompasses a heterogeneous group of tumors. Based upon the microarray of MBCs, these tumors showed features of basal-like carcinoma and myoepithelial differentiation. However, MBCs entity still remained unclear. So we performed a systematic research to explicit metaplastic breast carcinomas further. A panel of ER, PR, HER-2, CK5/6, CK14, P63 and EGFR were prepared for detection of MBCs, and fluorescence in situ hybridization for HER-2 gene amplification and ultrastructure observation were also performed. Sensitiveness between CK5/6 and other antibodies in diagnosis was analysed, and survival analysis was also carried out. ER, PR and HER-2 were negative. CK5/6 (12/12), CK14 (9/12), EGFR (10/12) and P63 (8/12) were positive. FISH for HER-2 displayed no amplification (ratio values < 1.8). Ultrastructure showed tonofibrils, thin filament and dense body in the cytoplasm. Significant statistical differences were detected between groups (F = 8.080, P = 0.000) of score of CK5/6, CK14, P63 and EGFR. Significant statistical differences were also detected between age and lymph node involvement and survival (χ(2) = 10.835, P = 0.004). MBCs may be actually basal-like carcinomas. In the diagnosis of MBCs, CK5/6, CK14, P63 and EGFR may be effective and CK5/6 may be more sensitive than CK14 and P63. Survival of MBCs may be associated with age and lymph node involvement. However, given the limitations of our research accumulated cases, prospective clinicopathologic studies are needed to further elucidate MBCs.