Molecular partitioning in ternary solutions of cellulose.

Neutron scattering measurements on the structure and dynamics of ternary solutions of microcrystalline cellulose (MC) in mixtures of an ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate and a polar organic solvent dimethylformamide (DMF) have shown that MC can be fully dissolved in solvent mixtures. Data also show the molecular partitioning of IL into coexisting states. The structure partitioning is manifested as IL adsorbed to cellulose molecules with additional IL self-assembled to form clusters in solution, while the dynamics partitioning shows dynamical heterogeneities of the IL with slow dynamics resembling neat IL and fast dynamics being coupled with the solvent. The composition dependence of the molecular partitioning results in a solubility gap in dilute cellulose solutions and a phase boundary criterion of the molar ratio of IL / MC ∼ 3 in more concentrated regimes. The two characteristics together define the main features of the dissolution phase diagram of ternary cellulose mixtures of MC / IL / DMF at the room temperature.

Phase Separation and Stack Alignment in Aqueous Cellulose Nanocrystal Suspension under Weak Magnetic Field.

Isotropic-nematic (I-N) transitions in cellulose nanocrystal (CNC) suspension and self-assembled structures in the isotropic and nematic phases were investigated using scattering and microscopy methods. A CNC suspension with a mass fraction of 7.4% spontaneously phase separated into an isotropic phase of 6.9% in the top layer and a nematic phase of 7.9% in the bottom layer. In both the phases, the CNC particles formed stacks with an interparticle distance being of ≈37 nm. One-dimensional small-angle neutron scattering (SANS) profiles due to both phases could be fitted using a stacking model considering finite particle sizes. SANS and atomic force microscopy studies indicate that the nematic phase in the bottom layer contains more populations of larger particles. A weak magnetic field of ≈0.5 T was able to induce a preferred orientation of CNC stacks in the nematic phase, with the stack normals being aligned with the field (perpendicular to the long axis of CNC particles). The Hermans orientation parameter, ⟨ P2⟩, was ≈0.5 for the nematic phase; it remained unchanged during the relaxation process of ≈10 h. The fraction of oriented CNC populations decreased during the relaxation; dramatic decrease occurred in the first 3 h. The top layer remained isotropic in the weak field. Polarized microscopy studies revealed that the nematic phase was chiral. Adjacent particles in a stack form a twisting angle of ≈0.6 °, resulting in a helix pitch distance of ≈22 µm.

Feasibility of real-time motion management with helical tomotherapy.

PURPOSE: This study investigates the potential application of image-based motion tracking and real-time motion correction to a helical tomotherapy system. METHODS: A kV x-ray imaging system was added to a helical tomotherapy system, mounted 90 degrees offset from the MV treatment beam, and an optical camera system was mounted above the foot of the couch. This experimental system tracks target motion by acquiring an x-ray image every few seconds during gantry rotation. For respiratory (periodic) motion, software correlates internal target positions visible in the x-ray images with marker positions detected continuously by the camera, and generates an internal-external correlation model to continuously determine the target position in three-dimensions (3D). Motion correction is performed by continuously updating jaw positions and MLC leaf patterns to reshape (effectively re-pointing) the treatment beam to follow the 3D target motion. For motion due to processes other than respiration (e.g., digestion), no correlation model is used - instead, target tracking is achieved with the periodically acquired x-ray images, without correlating with a continuous camera signal. RESULTS: The system's ability to correct for respiratory motion was demonstrated using a helical treatment plan delivered to a small (10 mm diameter) target. The phantom was moved following a breathing trace with an amplitude of 15 mm. Film measurements of delivered dose without motion, with motion, and with motion correction were acquired. Without motion correction, dose differences within the target of up to 30% were observed. With motion correction enabled, dose differences in the moving target were less than 2%. Nonrespiratory system performance was demonstrated using a helical treatment plan for a 55 mm diameter target following a prostate motion trace with up to 14 mm of motion. Without motion correction, dose differences up to 16% and shifts of greater than 5 mm were observed. Motion correction reduced these to less than a 6% dose difference and shifts of less than 2 mm. CONCLUSIONS: Real-time motion tracking and correction is technically feasible on a helical tomotherapy system. In one experiment, dose differences due to respiratory motion were greatly reduced. Dose differences due to nonrespiratory motion were also reduced, although not as much as in the respiratory case due to less frequent tracking updates. In both cases, beam-on time was not increased by motion correction, since the system tracks and corrects for motion simultaneously with treatment delivery.

Anisotropic, Transparent Films with Aligned Cellulose Nanofibers.

Transparent films or substrates are ubiquitously used in photonics and optoelectronics, with glass and plastics as traditional choice of materials. Transparent films made of cellulose nanofibers are reported recently. However, all these films are isotropic in nature. This work, for the first time, reports a remarkably facile and effective approach to fabricating anisotropic transparent films directly from wood. The resulting films exhibit an array of exceptional optical and mechanical properties. The well-aligned cellulose nanofibers in natural wood are maintained during delignification, leading to an anisotropic film with high transparency (≈90% transmittance) and huge intensity ratio of transmitted light up to 350%. The anisotropic film with well-aligned cellulose nanofibers has a mechanical tensile strength of up to 350 MPa, nearly three times of that of a film with randomly distributed cellulose nanofibers. Atomistic mechanics modeling further reveals the dependence of the film mechanical properties on the alignment of cellulose nanofibers through the film thickness direction. This study also demonstrates guided liquid transport in a mesoporous, anisotropic wood film and its possible application in enabling new nanoelectronic devices. These unique and highly desirable properties of the anisotropic transparent film can potentially open up a range of green electronics and nanofluidics.

Disease impact on general well-being and therapeutic expectations of European Type II and Type III spinal muscular atrophy patients.

Spinal muscular atrophy (SMA) is a neurodegenerative disorder showing a broad clinical spectrum and no cure to date. To design and select evaluation criteria for the potential assessment of drugs currently being developed, the patient's perspective is critical. A survey, aiming to obtain a view on the current clinical state of European Type II and Type III SMA patients, the impact of this situation on their quality of life and their expectations regarding clinical development, was carried out by SMA-Europe member organizations in July 2015. A questionnaire was set up, translated into 8 European languages and sent out directly via electronic mailing to the targeted SMA patient population by the respective European patient organizations. We were able to collect 822 valid replies in less than two weeks. The questionnaire captured the current abilities of the respondents, their perception of the disease burden which appeared very similar across Europe despite some regional variations in care. According to the great majority of the respondents, stabilization of their current clinical state would represent a therapeutic progress for a compelling majority of the respondents to the questionnaire.

High Temperature Carbonized Grass as a High Performance Sodium Ion Battery Anode.

Hard carbon is currently considered the most promising anode candidate for room temperature sodium ion batteries because of its relatively high capacity, low cost, and good scalability. In this work, switchgrass as a biomass example was carbonized under an ultrahigh temperature, 2050 °C, induced by Joule heating to create hard carbon anodes for sodium ion batteries. Switchgrass derived carbon materials intrinsically inherit its three-dimensional porous hierarchical architecture, with an average interlayer spacing of 0.376 nm. The larger interlayer spacing than that of graphite allows for the significant Na ion storage performance. Compared to the sample carbonized under 1000 °C, switchgrass derived carbon at 2050 °C induced an improved initial Coulombic efficiency. Additionally, excellent rate capability and superior cycling performance are demonstrated for the switchgrass derived carbon due to the unique high temperature treatment.

Thermally conductive, dielectric PCM-boron nitride nanosheet composites for efficient electronic system thermal management.

Phase change materials (PCMs) possessing ideal properties, such as superior mass specific heat of fusion, low cost, light weight, excellent thermal stability as well as isothermal phase change behavior, have drawn considerable attention for thermal management systems. Currently, the low thermal conductivity of PCMs (usually less than 1 W mK-1) greatly limits their heat dissipation performance in thermal management applications. Hexagonal boron nitride (h-BN) is a two-dimensional material known for its excellent thermally conductive and electrically insulating properties, which make it a promising candidate to be used in electronic systems for thermal management. In this work, a composite, consisting of h-BN nanosheets (BNNSs) and commercialized paraffin wax was developed, which inherits high thermally conductive and electrically insulating properties from BNNSs and substantial heat of fusion from paraffin wax. With the help of BNNSs, the thermal conductivity of wax-BNNS composites reaches 3.47 W mK-1, which exhibits a 12-time enhancement compared to that of pristine wax (0.29 W mK-1). Moreover, an 11.3-13.3 MV m-1 breakdown voltage of wax-BNNS composites was achieved, which shows further improved electrical insulating properties. Simultaneously enhanced thermally conductive and electrically insulating properties of wax-BNNS composites demonstrate their promising application for thermal management in electronic systems.

Highly Anisotropic, Highly Transparent Wood Composites.

For the first time, two types of highly anisotropic, highly transparent wood composites are demonstrated by taking advantage of the macro-structures in original wood. These wood composites are highly transparent with a total transmittance up to 90% but exhibit dramatically different optical and mechanical properties.

Self-Powered Human-Interactive Transparent Nanopaper Systems.

Self-powered human-interactive but invisible electronics have many applications in anti-theft and anti-fake systems for human society. In this work, for the first time, we demonstrate a transparent paper-based, self-powered, and human-interactive flexible system. The system is based on an electrostatic induction mechanism with no extra power system appended. The self-powered, transparent paper device can be used for a transparent paper-based art anti-theft system in museums or for a smart mapping anti-fake system in precious packaging and documents, by virtue of the advantages of adding/removing freely, having no impairment on the appearance of the protected objects, and being easily mass manufactured. This initial study bridges the transparent nanopaper with a self-powered and human-interactive electronic system, paving the way for the development of smart transparent paper electronics.

Investigation of accelerated partial breast patient alignment and treatment with helical tomotherapy unit.

PURPOSE: To determine the precision of megavoltage computed tomography (MVCT)-based alignment of the seroma cavity for patients undergoing partial breast irradiation; and to determine whether accelerated partial breast irradiation (APBI) plans can be generated for TomoTherapy deliveries that meet the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39/Radiation Therapy Oncology Group (RTOG) 0413 protocol guidelines for target coverage and normal tissue dose limitations. METHODS AND MATERIALS: We obtained 50 MVCT images from 10 patients. An interuser study was designed to assess the alignment precision. Using a standard helical and a fixed beam prototype ("topotherapy") optimizer, two APBI plans for each patient were developed. RESULTS: The precision of the MVCT-based seroma cavity alignment was better than 2 mm if averaged over the patient population. Both treatment techniques could be used to generate acceptable APBI plans for patients that fulfilled the recommended NSABP B-39/RTOG-0413 selection criteria. For plans of comparable treatment time, the conformation of the prescription dose to the target was greater for helical deliveries, while the ipsilateral lung dose was significantly reduced for the topotherapy plans. CONCLUSIONS: The inherent volumetric imaging capabilities of a TomoTherapy Hi-Art unit allow for alignment of patients undergoing partial breast irradiation that is determined from the visibility of the seroma cavity on the MVCT image. The precision of the MVCT-based alignment was better than 2 mm (+/-standard deviation) when averaged over the patient population. Using the NSABP B-39/RTOG-0413 guidelines, acceptable APBI treatment plans can be generated using helical- or topotherapy-based delivery techniques.