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Thickness‐dependent crystal structure, surface morphology, surface energy, and molecular structure and microstructure of a series of polycrystalline pentacene films with different film thickness ranging from several monolayers to the several hundred nanometers have been investigated using X‐ray diffraction (XRD), atomic force microscopy (AFM), contact angle meter, and Raman spectroscopy. XRD studies indicate that thin film polymorphs transformation behaviours are from the orthorhombic phase to the thin‐film phase and then to the triclinic bulk phase as measured by the increased tilt angle (θtilt) of the pentacene molecule from the c‐axis toward the a‐axis. We propose a growth model that rationalizes the θtilt increased along with increasing film thickness in terms of grain size and surface energy varying with film growth using AFM combined with contact angle measurements. The vibrational characterizations of pentacene molecules in different thickness films were investigated by Raman spectroscopy compared to density functional theory calculations of an isolated molecule. In combination with XRD and AFM the method enables us to distinguish the molecular microstructures in different thin film polymorphs. We proposed a methodology to probe the microscopic parameters determining the carrier transport properties based on Davydov splitting and the characteristics of aromatic C–C stretching modes in Raman spectra. When compared to the triclinic bulk phase at a high thickness, we suggest that the first few monolayer structures located at the dielectric surface could have inferior carrier transport properties due to weak intermolecular interactions, large molecular relaxation energy, and more grain boundaries.

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Human immunodeficiency virus infection is an illness with protean manifestations including hematological abnormalities. Thromboembolic complications in HIV-infected patients have been described. Recent literature describes an incidence ranging from 0.26% to 7.6%; higher incidence is seen in patients with active opportunistic infections or malignancy, and in patients with the acquired immunodeficiency syndrome. A variety of potential mechanisms have been proposed to account for the observed hypercoagulability in HIV-infected patients. These include the presence of antiphospholipid-anticardiolipin antibodies, decreased activities of natural anticoagulants (especially protein S), and increased platelet activation. Recent epidemiological studies emphasize the increased incidence of thromboembolic events including myocardial infarction in the HIV-infected population after the introduction of highly active antiretroviral therapy. The use of protease inhibitors in particular is implicated. A hypercoagulable state and especially thromboses are emerging as clinical issues in HIV-infected patients. Further studies are in order to more clearly delineate the pathophysiologic mechanism(s) of thromboses in HIV-infected patients.

A novel oligomeric phosphorous-nitrogen-containing intumescent flame retardant poly (4,4diaminodiphenylmethane-O-bicyclicpentaerythritol phosphate-phosphate) (PDBPP) is synthesized, and subsequently fullerene (C 60 )-decorated oligomeric intumescent flame retardant, C 60 -d-PDBPP, is fabricated via chemical grafting reaction and characterized. The grafting degree of C 60 is as high as 70 wt%, and C 60 -d-PDBPP nanoparticles can homogeneously disperse in polypropylene matrix since the grafting process may prevent the aggregation of C 60 particles. Upon incorporating C 60 -d-PDBPP, thermal oxidation degradation of polypropylene is considerably delayed. When the concentration of C 60 -d-PDBPP reached 2 wt%, the initial degradation temperature (T 5 : the temperature where 5wt% mass loss occurred) and maximum weight loss rate temperature (T max ) display an increase of about 72 C and 80 C, respectively. Moreover, C 60 -d-PDBPP can remarkably reduce the peak heat release rate (PHRR) values of polypropylene, and consequently slow down the combustion process of nanocomposites. Additionally, to some extent it prolongs the time to ignition (t ign ) and time to peak heat release rate (t PHRR ), all of which are very important parameters for evaluating the fire retardancy of a polymeric material.