Alignment and Photopolymerization of Hexa-peri-hexabenzocoronene Derivatives Carrying Diacetylenic Side Chains for Charge-Transporting Application.

Thin films of four discotic liquid-crystalline hexa-peri-hexabenzocoronene (HBC) derivatives carrying three diacetylenic side chains and three saturated alkyl chains at different positions around the central HBC core were prepared on phenyltrichlorosilane-modified SiO2 substrate by the Chinese brush-coating method. The brush-coated films of molecules with D3h symmetry and C1 symmetry all exhibited anisotropic alignment with an edge-on orientation and molecular π-π stacking along the coating direction on the surface, in contrast to the spin-coated films, where a mixture of face-on and edge-on orientations was obtained. Hexagonally packed columnar structure or lamella-like columnar structure was obtained, depending on the location of the diacetylenic unit along the chain. UV irradiation of the films resulted in cross-linking/polymerization of the molecular columns. Among them, the lamella-like structure with a diacetylene unit closer to the HBC core gave more closely packed and ordered HBC arrays with the poly(ene-yne) backbones stretching along the column direction, based on a variety of experimental evidence. A thin-film transistor based on this irradiated film gave a highest mobility of 1.5 cm2 V-1 s-1 along the column direction, which is a 3 orders of magnitude improvement over that of the monomeric film. However, for those with a diacetylenic unit extended farther away from the core, cross-linking between neighboring columns was suggested to occur and no mobility can be measured for devices based on those films.

Direct comparison between subnanometer hydration structures on hydrophilic and hydrophobic surfaces via three-dimensional scanning force microscopy.

Investigating interfacial water ordering on solid surfaces with different hydrophobicities is fundamentally important. Here, we prepared hydrophilic mica substrates with some areas covered by mildly hydrophobic graphene layers and studied the resulting hydration layers using three-dimensional (3D) force measurements based on frequency-modulation atomic force microscopy. Hydration layers of 0.3-0.6 nm were detected on bare graphene regions; these layers were considerably larger than the spacing measured on mica (0.2-0.3 nm). On the graphene-covered regions, we also observed the formation of special ordered structures of adsorbates over time, on which, surprisingly, no prominent hydration layers were detected. Based on these findings, we present one possible scenario to describe the formation process of the ordered interfacial structures and the enhanced oscillation period in the force profiles. This work also demonstrates the capability and significance of 3D force measurements in probing hydration behaviors on a heterogeneous substrate with a lateral resolution smaller than several nanometers.

High-Resolution Characterization of Preferential Gas Adsorption at the Graphene-Water Interface.

The contact of water with graphene is of fundamental importance and of great interest for numerous promising applications, but how graphene interacts with water remains unclear. Here we used atomic force microscopy (AFM) to investigate hydrophilic mica substrates with some regions covered by mechanically exfoliated graphene layers in water. In water containing air gas close to the saturation concentration (within ∼40%), cap-shaped nanostructures (or interfacial nanobubbles) and ordered-stripe domains were observed on graphene-covered regions but not on pure mica regions. These structures did not appear on graphene when samples were immersed in highly degassed water, indicating that their formation was caused by the adsorption of gas dissolved in water. Thus, atomically thin graphene, even at a narrow width of 20 nm, changes the local surface chemistry of a highly hydrophilic substrate. Furthermore, surface hydrophobicity significantly affects gas adsorption, which has broad implications for diverse phenomena in water.

The role of LAT-PLCγ1 interaction in γδ T cell development and homeostasis.

LAT is a transmembrane adaptor protein that is vital for integrating TCR-mediated signals to modulate T cell development, activation, and proliferation. Upon T cell activation, LAT is phosphorylated and associates with Grb2, Gads, and PLCγ1 through its four distal tyrosine residues. Mutation of one of these tyrosines, Y136, abolishes LAT binding to PLCγ1. This results in impaired TCR-mediated calcium mobilization and Erk activation. CD4 αß T cells in LATY136F knock-in mice undergo uncontrolled expansion, resulting in a severe autoimmune syndrome. In this study, we investigated the importance of the LAT-PLCγ1 interaction in γδ T cells by crossing LATY136F mice with TCRß(-/-) mice. Our data showed that the LATY136F mutation had no major effect on homeostasis of epithelial γδ T cells, which could be found in the skin and small intestine. Interestingly, a population of CD4(+) γδ T cells in the spleen and lymph nodes underwent continuous expansion and produced elevated amounts of IL-4, resulting in an autoimmune syndrome similar to that caused by αß T cells in LATY136F mice. Development of these hyperproliferative γδ T cells was not dependent on MHC class II expression or CD4, and their proliferation could be suppressed, in part, by regulatory T cells. Our data indicated that a unique subset of CD4 γδ T cells can hyperproliferate in LATY136F mice and suggested that LAT-PLCγ1 signaling may function differently in various subsets of γδ T cells.

Surfactant-directed fabrication of supercrystals from the assembly of polyhedral Au-Pd core-shell nanocrystals and their electrical and optical properties.

Au-Pd core-shell nanocrystals with cubic, truncated cubic, cuboctahedral, truncated octahedral, and octahedral structures have been employed to form micrometer-sized polyhedral supercrystals by both the droplet evaporation method and novel surfactant diffusion methods. Observation of cross-sectional samples indicates shape preservation of interior nanocrystals within a supercrystal. Low-angle X-ray diffraction techniques and electron microscopy have been used to confirm the presence of surfactant between contacting nanocrystals. By diluting the nanocrystal concentration or increasing the solution temperature, supercrystal size can be tuned gradually to well below 1 µm using the surfactant diffusion method. Rectangular supercrystal microbars were obtained by increasing the amounts of cubic nanocrystals and surfactant used. Au-Ag core-shell cubes and PbS cubes with sizes of 30-40 nm have also been fabricated into supercrystals, showing the generality of the surfactant diffusion approach to form supercrystals with diverse composition. Electrical conductivity measurements on single Au-Pd supercrystals reveal loss of metallic conductivity due to the presence of insulating surfactant. Cubic Au-Pd supercrystals show infrared absorption at 3.2 µm due to extensive plasmon coupling. Mie-type resonances centered at 9.8 µm for the Au-Pd supercrystals disappear once the Pd shells are converted into PdH after hydrogen absorption.

The requirement of linker for activation of T cells in the primary and memory responses of CD8 T cells.

Linker for activation of T cells (LAT) is a transmembrane adaptor protein that links TCR engagement to downstream signaling events. Although it is clear that LAT is essential in thymocyte development and initiation of T cell activation, its function during T cell expansion, contraction, and memory formation remains unknown. To study the role of TCR-mediated signaling in CD8 T cells during the course of pathogen infection, we used an inducible mouse model to delete LAT in Ag-specific CD8 T cells at different stages of Listeria infection and analyzed the effect of deletion on T cell responses. Our data showed that LAT is important for maintaining CD8 T cell expansion during the priming phase; however, it is not required for CD8 T cell contraction and memory maintenance. Moreover, LAT deficiency accelerates memory differentiation during the effector-to-memory transition, leading to a higher frequency of KLRG1(low)IL-7R(high)CD62L(high) memory T cells. Nonetheless, these LAT-deficient memory T cells were unable to proliferate or produce cytokines upon secondary infection. Our data demonstrated that, although TCR-mediated signaling is dispensable for contraction and memory maintenance, it regulates CD8 T cell memory differentiation and is essential for the memory response against pathogens.

Risk of dementia after anaesthesia and surgery.

BACKGROUND: The potential relationship between anaesthesia, surgery and onset of dementia remains elusive. AIMS: To determine whether the risk of dementia increases after surgery with anaesthesia, and to evaluate possible associations among age, mode of anaesthesia, type of surgery and risk of dementia. METHOD: The study cohort comprised patients aged 50 years and older who were anaesthetised for the first time since 1995 between 1 January 2004 and 31 December 2007, and a control group of randomly selected patients matched for age and gender. Patients were followed until 31 December 2010 to identify the emergence of dementia. RESULTS: Relative to the control group, patients who underwent anaesthesia and surgery exhibited an increased risk of dementia (hazard ratio = 1.99) and a reduced mean interval to dementia diagnosis. The risk of dementia increased in patients who received intravenous or intramuscular anaesthesia, regional anaesthesia and general anaesthesia. CONCLUSIONS: The results of our nationwide, population-based study suggest that patients who undergo anaesthesia and surgery may be at increased risk of dementia.

Tyrosine phosphorylation-independent regulation of lipopolysaccharide-mediated response by the transmembrane adaptor protein LAB.

Linker for activation of B cells (LAB)/non-T cell activation linker is a transmembrane adaptor protein that functions in immunoreceptor-mediated signaling. Published studies have shown that LAB has both positive and negative roles in regulating TCR and high-affinity Fc receptor-mediated signaling and cellular function. In this study, we showed that LAB was also expressed in dendritic cells and that LAB deficiency affected LPS-mediated signaling and cytokine production. LPS-mediated MAPK activation was enhanced in LAB(-/-) bone marrow-derived dendritic cells. These bone marrow-derived dendritic cells also produced more TNF-α, IL-6, and IL-10 than wild-type cells. Moreover, LAB(-/-) mice were hyperresponsive to LPS-induced septic shock. These data indicated that LAB has a negative role in LPS-mediated responses. By using LAB knockin mice, which harbor mutations at five membrane-distal tyrosines, we further showed that, in contrast to its role in immunoreceptor-mediated signaling, LAB function in LPS-mediated signaling pathway did not depend on its tyrosine phosphorylation. Our study suggested a novel mechanism by which LAB functions in the regulation of innate immunity.

Enhancing the Versatility and Performance of Soft Robotic Grippers, Hands, and Crawling Robots Through Three-Dimensional-Printed Multifunctional Buckling Joints.

Soft robotic grippers and hands offer adaptability, lightweight construction, and enhanced safety in human-robot interactions. In this study, we introduce vacuum-actuated soft robotic finger joints to overcome their limitations in stiffness, response, and load-carrying capability. Our design-optimized through parametric design and three-dimensional (3D) printing-achieves high stiffness using vacuum pressure and a buckling mechanism for large bending angles (>90°) and rapid response times (0.24 s). We develop a theoretical model and nonlinear finite-element simulations to validate the experimental results and provide valuable insights into the underlying mechanics and visualization of the deformation and stress field. We showcase versatile applications of the buckling joints: a three-finger gripper with a large lifting ratio (∼96), a five-finger robotic hand capable of replicating human gestures and adeptly grasping objects of various characteristics in static and dynamic scenarios, and a planar-crawling robot carrying loads 30 times its weight at 0.89 body length per second (BL/s). In addition, a jellyfish-inspired robot crawls in circular pipes at 0.47 BL/s. By enhancing soft robotic grippers' functionality and performance, our study expands their applications and paves the way for innovation through 3D-printed multifunctional buckling joints.

Seed-mediated growth of ultralong gold nanorods and nanowires with a wide range of length tunability.

This study reports a systematic approach to synthesize ultralong gold nanorods and nanowires using a seed-mediated growth approach. In the first series, the effect of growth solution pH on the lengths of nanorods prepared was investigated. Interestingly, although shorter rods (230-310 nm) were produced in a basic solution environment than in an acidic condition (330-410 nm), the nanorod yield is greatly improved with relatively few nanoplate byproducts formed. Nanorod growth proceeds quickly in a basic solution as evidenced by the fast solution color changes. By adjusting several experimental parameters with the aim to elongate the nanorod length in a tunable fashion, gold nanorods and nanowires with average lengths from 580 to 2850 nm can be synthesized by progressively increasing the HNO3 concentration in the final growth solution. Nanowire growth in a highly acidic solution is slower, and a substantially longer time is needed to reach long lengths. Further extension of the nanowire length can be achieved simply by reducing the volume of second growth solution transferred to the final growth solution. Nanorods and nanowires with lengths spanning from 700 nm to 4.5 µm were prepared in this series of experimental conditions. The longest nanowires can reach a length of up to 6 µm. The nanowires still maintain thin average diameters of 33-53 nm. The ability to make gold nanorods and nanowires over this exceptionally wide and useful length range is exciting because applications and demonstrations using ultralong gold nanorods and nanowires of most suitable lengths are now possible.

Torsional resonance mode atomic force microscopy in liquid with Lorentz force actuation.

In this work, we present a design based on Lorentz force induction to excite pure torsional resonances of different types of cantilevers in air as well as in water. To demonstrate the atomic force microscopy imaging capability, the phase-modulation torsional resonance mode is employed to resolve fine features of purple membranes in a buffer solution. Most importantly, force-versus-distance curves using a relatively stiff cantilever can clearly detect the characteristic oscillatory profiles of hydration layers at a water-mica interface, indicating the high force sensitivity of the torsional mode. The high resonance frequencies and high quality-factors for the torsional mode may be of great potential for high-speed and high-sensitivity imaging in aqueous environment.

Computational and bioinformatics frameworks for next-generation whole exome and genome sequencing.

It has become increasingly apparent that one of the major hurdles in the genomic age will be the bioinformatics challenges of next-generation sequencing. We provide an overview of a general framework of bioinformatics analysis. For each of the three stages of (1) alignment, (2) variant calling, and (3) filtering and annotation, we describe the analysis required and survey the different software packages that are used. Furthermore, we discuss possible future developments as data sources grow and highlight opportunities for new bioinformatics tools to be developed.

Molecular layer of gaslike domains at a hydrophobic-water interface observed by frequency-modulation atomic force microscopy.

It was numerically predicted that dissolved gas particles could enrich and adsorb at hydrophobic-liquid interfaces. Here we observe nucleation and growth of bright patches of ∼0.45 nm high on the graphite surface in pure water with frequency-modulation atomic force microscopy when the dissolved gas concentration is below the saturation level. The bright patches, suspected to be caused by adsorption of nitrogen molecules at the graphite-water interface, are composed of domains of a rowlike structure with the row separation of 4.2 ± 0.3 nm. The observation of this ordered adlayer might underline the gas segregation at various water interfaces.

The importance of LAT in the activation, homeostasis, and regulatory function of T cells.

LAT (linker for activation of T cells) is a transmembrane adaptor protein that plays an essential role in TCR-mediated signaling and thymocyte development. Because LAT-deficient mice have an early block in thymocyte development, we utilized an inducible system to delete LAT in primary T cells to study LAT function in T cell activation, homeostasis, and survival. Deletion of LAT caused primary T cells to become unresponsive to stimulation from the TCR and impaired T cell homeostatic proliferation and long term survival. Furthermore, deletion of LAT led to reduced expression of Foxp3, CTLA-4, and CD25 in T(reg) cells and impaired their function. Consequently, mice with LAT deleted developed a lymphoproliferative syndrome similar to that in LATY136F mice, although less severe. Our data implicate that LAT has positive and negative roles in the regulation of mature T cells.

Fabrication of Au-Pd core-shell heterostructures with systematic shape evolution using octahedral nanocrystal cores and their catalytic activity.

By using octahedral gold nanocrystals with sizes of approximately 50 nm as the structure-directing cores for the overgrowth of Pd shells, Au-Pd core-shell heterostructures with systematic shape evolution can be directly synthesized. Core-shell octahedra, truncated octahedra, cuboctahedra, truncated cubes, and concave cubes were produced by progressively decreasing the amount of the gold nanocrystal solution introduced into the reaction mixture containing cetyltrimethylammonium bromide (CTAB), H(2)PdCl(4), and ascorbic acid. The core-shell structure and composition of these nanocrystals has been confirmed. Only the concave cubes are bounded by a variety of high-index facets. This may be a manifestation of the release of lattice strain with their thick shells at the corners. Formation of the [CTA](2)[PdBr(4)] complex species has been identified spectroscopically. Time-dependent UV-vis absorption spectra showed faster Pd source consumption rates in the growth of truncated cubes and concave cubes, while a much slower reduction rate was observed in the generation of octahedra. The concave cubes and octahedra were used as catalysts for a Suzuki coupling reaction. They can all serve as effective and recyclable catalysts, but the concave cubes gave higher product yields with a shorter reaction time attributed to their high-index surface facets. The concave cubes can also catalyze a wide range of Suzuki coupling reactions using aryl iodides and arylboronic acids with electron-donating and -withdrawing substituents.

Soft-contact imaging in liquid with frequency-modulation torsion resonance mode atomic force microscopy.

In this work, we demonstrate that high-resolution imaging in water with a soft contact between the tip and the sample can be achieved with frequency-modulation torsional resonance (FM-TR) mode atomic force microscopy (AFM). This mode is very sensitive to the contact of the tip with the sample surface. A sharp jump in the resonance frequency shift occurs when the tip is getting in touch with the sample. Individual atomic features on mica surfaces can be resolved with a relatively large tip. The tip applies very small normal and lateral forces on the surface. In addition, even a long and compliant AFM cantilever can achieve a high quality factor and a high resonant frequency for the torsional oscillation in water. Along with several other advantages, this mode is very suitable for future development of high-sensitivity, high-resolution, high-speed AFM for the study of dynamic biological processes in liquid.

Probable variant Creutzfeldt­Jakob disease in Asia: a case report from Taiwan and review of two prior cases.

New variant Creutzfeldt­Jakob disease (vCJD) was first identified in the UK in 1996, and was causally linked to bovine spongiform encephalopathy. Herein we report the first case of vCJD in Taiwan: a 34-year-old man who had lived in the UK between 1989 and 1997. The patient presented with depression, irritability, personality change, painful feet and allodynia, followed by gait ataxia and cognitive impairment. Electroencephalograms did not show the typical appearance of sporadic CJD. The cerebrospinal fluid 14-3-3 protein immunoassay was negative. Brain magnetic resonance imaging revealed high signal lesions involving bilateral caudate nuclei, left lentiform nucleus, bilateral dorsomedial thalami and pulvinar on fluid-attenuation inversion recovery, T2- and diffusion-weighted imaging. Prion protein gene analysis showed homozygous for methionine at codon 129. The patient developed akinetic mutism at 16 months and died at 28 months after onset. The clinical presentation and neuroimaging findings were compatible with the vCJD cases reported since 1996, and met the World Health Organization Case Definition for probable vCJD. In this communication, we also review two other cases of vCJD in Asia. All three cases were assumed as imported cases from the UK because of the residential or travel history of the patients.

A horizontal-type scanning near-field optical microscope with torsional mode operation toward high-resolution and non-destructive imaging of soft materials.

We design and build a horizontal-type aperture based scanning near-field optical microscope (a-SNOM) with superior mechanical stability toward high-resolution and non-destructive topographic and optical imaging. We adopt the torsional mode in AFM (atomic force microscopy) operation to achieve a better force sensitivity and a higher topographic resolution when using pyramidal a-SNOM tips. The performance and stability of the AFM are evaluated through single-walled carbon nanotube and poly(3-hexyl-thiophene) nanowire samples. An optical resolution of 93 nm is deduced from the a-SNOM imaging of a metallic grating. Finally, a-SNOM fluorescence imaging of soft lipid domains is successfully achieved without sample damage by our horizontal-type a-SNOM instrument with torsional mode AFM operation.