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Graphene oxide (GO) has shown great potential as a component in various devices due to its excellent solution processability and two-dimensional structure. However, the oxygenated form of graphene has a moderate charge-transport capability. The latter parameter may be enhanced through controlled deoxygenation of GO with subsequent tuning of its work function (WF). Various reduction approaches were employed to investigate the effect of the oxygen content on the work function of GO derivatives as thin films on an indium tin oxide substrate. Such films were reduced by stepwise thermal annealing in ultrahigh vacuum up to 650 °C, by chemical reduction with hydrazine, or by a combination of chemical and thermal reduction processes. The effect of the GO film thickness and the flake size on the WF was also investigated. UV photoelectron spectroscopy and X-ray photoelectron spectroscopy were used to correlate the WF of GO derivatives with their oxygen content. The results showed that the WF is strongly dependent on the oxygen content, reaching a ∼1 eV difference between GO and highly reduced GO, under the specific reduction conditions. The film thickness affects the work function, since in thin films interaction with the substrate is pronounced. Finally, the WF of reduced GO after combination of chemical and thermal reduction reaches its lowest value of 4.20 eV, due to the presence of heteroatoms which doped the surface.

Achieving structural superlubricity in graphitic samples of macro-scale size is particularly challenging due to difficulties in sliding large contact areas of commensurate stacking domains.Here, we show the presence of macro-scale structural superlubricity between two randomly stacked graphene layers produced by both mechanical exfoliation and CVD. By measuring the shifts of Raman peaks under strain we estimate the values of frictional interlayer shear stress (ILSS) in the superlubricity regime (mm scale) under ambient conditions. The random incommensurate stacking, the presence of wrinkles and the mismatch in the lattice constant between two graphene layers induced by the tensile strain differential are considered responsible for the facile shearing at the macroscale. Furthermore, molecular dynamic simulations show that the stick-slip behaviour does not hold for achiral shearing directions for which the ILSS decreases substantially, supporting the experimental observations. Our results pave the way for overcoming several limitations in achieving macroscale superlubricity in graphene.

The development of three-dimensional (3D) porous graphitic structures is of great interest for electrochemical sensing applications as they can support fast charge transfer and mass transport through their extended, large surface area networks. In this work, we present the facile fabrication of conductive and porous graphitic electrodes by direct laser writing techniques. Irradiation of commercial polyimide sheets (Kapton tape) was performed using a low-cost laser engraving machine with visible excitation wavelength (405 nm) at low power (500 mW), leading to formation of 3D laser-induced graphene (LIG) structures. Systematic correlation between applied laser dwell time per pixel (“dwell time”) and morphological/structural properties of fabricated electrodes showed that conductive and highly 3D porous structures with spectral signatures of nanocrystalline graphitic carbon materials were obtained at laser dwell times between 20 and 110 ms/pix, with graphenelike carbon produced at 50 ms/pix dwell time, with comparable properties to LIG obtained with high cost CO2 lasers. Electrochemical characterization with inner and outer sphere mediators showed fast electron transfer rates, comparable to previously reported 2D/3D graphene-based materials and other graphitic carbon electrodes. This work opens the way to the facile fabrication of low-cost, disposable electrochemical sensor platforms for decentralized assays.

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Supplementary Information accompanies the paper on the Leukemia website (http://www.nature.com/leu)Lymphocyte subpopulation imbalances, bone marrow hematopoiesis and histopathology in rituximab-treated lymphoma patients with late-onset neutropenia Leukemia (2008) Several observations implicate the administration of rituximab in the development of severe late-onset neutropenia (LON) in some patients with lymphoma treated with rituximab±chemo-therapy. [1][2][3][4][5] The incidence of LON varies between series; this might be explained, at least in part, by the failure to detect some neutropenic episodes due to their short duration, the relatively long time to onset and the usually uncomplicated course. However, there is a gradual increase in the frequency of rituximab-related LON probably due to the widespread use of rituximab in the standard treatment of lymphomas and also due to the ongoing awareness for this event.Several groups, including ours, have provided indirect evidence to implicate an immune-mediated mechanism in the pathogenesis of rituximab-associated LON. [1][2][3]6 However, published data are mainly based on small series and are often contradictory, perhaps due to the selective evaluation of isolated parameters. Our previous studies suggesting that LON in rituximab-treated lymphoma patients may be associated with T-cell large granular lymphocytic (T-LGL) proliferation 1-2 alluded to the possibility of altered T-cell responses associated with B-cell depletion induced by rituximab. To probe this hypothesis further, in the present study, we performed a detailed immunological and immunohistological study looking for quantitative changes and/or an activated profile of lymphocytes in rituximab-treated patients with LON, focusing on the possibility of T-cell-mediated suppression of bone marrow (BM) hematopoiesis.The study included 12 patients (10 men and 2 women) with a median age of 48 years (range, 26-67 years) who developed unexplained LON after treatment with rituximab±chemother-apy for diffuse large B-cell lymphoma (DLCL; n ¼ 4), chronic lymphocytic leukemia (CLL; n ¼ 4), mantle-cell lymphoma (MCL; n ¼ 3) or splenic marginal-zone lymphoma (SMZL; n ¼ 1). LON was defined as the unexplained reduction in neutrophil counts p1.0 Â 10 9 l À1 (grade 3 according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC)) following neutrophil recovery after completion of the intended treatment with rituximab±chemotherapy, without evidence of disease progression and before addition of chemotherapy. One DLCL patient developed neutropenia while on maintenance monotherapy with rituximab. The remainder (n ¼ 11) received rituximab in combination with CHOP (DLCL, MCL, SMZL) or fludarabine-cyclophosphamide (CLL). LON occurred at a median of 95 (range, 67-420) days after the last administration of rituximab. Neutrophil nadir during neutropenia episodes in each patient ranged from 0.01 Â 10 9 to 0.85 Â 10 9 l À1 (median 0.52 Â 10 9 l À1 ). The recovery from neutropenia was observed at a median of 56 (range, 28-...

Organometal halide perovskite solar cells have been constructed using soluble tetra-nbutyl-copper phthalocyanine as hole transporting material. Devices were constructed and characterized under ambient conditions of 50-60% ambient humidity. Soluble copper phthalocyanine gave a modest PCE of 7.3% but when a buffer layer of either Al 2 O 3 or graphene oxide was introduced between the perovskite and the hole transporting layer the cell efficiency extensively increased and reached 14.4% in the presence of graphene oxide.Corresponding data obtained by employing the standard spiro-OMeTAD as hole transporter gave equivalent performance. Combination then of tetra-n-butyl-copper phthalocyanine with graphene oxide offers a very good alternative of simpler and stable materials for perovskite solar cell construction. The presently recorded data highlight the role of the buffer layer, especially graphene oxide, as the material which blocks shunt paths and facilitates hole transfer between the perovskite and the hole transporting layer.