Nanofluidic Ion Transport through Reconstructed Layered Materials

Electrolytes confined in nanochannels with characteristic dimensions comparable to the Debye length show transport behaviors deviating from their bulk counterparts. Fabrication of nanofluidic devices typically relies on expensive lithography techniques or the use of sacrificial templates with sophisticated growth and processing steps. Here we demonstrate an alternative approach where unprecedentedly massive arrays of nanochannels are readily formed by restacking exfoliated sheets of layered materials, such as graphene oxide (GO). Nanochannels between GO sheets are successfully constructed as manifested by surface-charge-governed ion transport for electrolyte concentrations up to 50 mM. Nanofluidic devices based on reconstructed layer materials have distinct advantages such as low cost, facile fabrication, ease of scaling up to support high ionic currents, and flexibility. Given the rich chemical, physical, and mechanical properties of layered materials, they should offer many exciting new opportunities for studying and even manufacturing nanofluidic devices

Vertical Organic Nanowire Arrays: Controlled Synthesis and Chemical Sensors

Vertical Organic Nanowire Arrays: Controlled Synthesis and Chemical Sensor

Effect of Sheet Morphology on the Scalability of Graphene-Based Ultracapacitors

Graphene is considered a promising ultracapacitor material toward high power and energy density because of its high conductivity and high surface area without pore tortuosity. However, the two-dimensional (2D) sheets tend to aggregate during the electrode fabrication process and align perpendicular to the flow direction of electrons and ions, which can reduce the available surface area and limit the electron and ion transport. This makes it hard to achieve scalable device performance as the loading level of the active material increases. Here, we report a strategy to solve these problems by transforming the 2D graphene sheet into a crumpled paper ball structure. Compared to flat or wrinkled sheets, the crumpled graphene balls can deliver much higher specific capacitance and better rate performance. More importantly, devices made with crumpled graphene balls are significantly less dependent on the electrode mass loading. Performance of graphene-based ultracapacitors can be further enhanced by using flat graphene sheets as the binder for the crumpled graphene balls, thus eliminating the need for less active binder materials

Langmuir−Blodgett Assembly of Graphite Oxide Single Layers

Single-layer graphite oxide can be viewed as an unconventional type of soft material and has recently been recognized as a promising material for composite and electronics applications. It is of both scientific curiosity and technical importance to know how these atomically thin sheets assemble. There are two fundamental geometries of interacting single layers: edge-to-edge and face-to-face. Such interactions were studied at the air−water interface by Langmuir−Blodgett assembly. Stable monolayers of graphite oxide single layers were obtained without the need for any surfactant or stabilizing agent, due to the strong electrostatic repulsion between the 2D confined layers. Such repulsion also prevented the single layers from overlapping during compression, leading to excellent reversibility of the monolayers. In contrast to molecular and hard colloidal particle monolayers, the single layers tend to fold and wrinkle at edges to resist collapsing into multilayers. The monolayers can be transferred to a substrate, readily creating a large area of flat graphite oxide single layers. The density of such films can be continuously tuned from dilute, close-packed to overpacked monolayers of interlocking single layers. For size-mismatched single layers, face-to-face interaction caused irreversible stacking, leading to double layers. The graphite oxide monolayers can be chemically reduced to graphene for electronic applications such as transparent conducting thin films

Self-Charging Textile Woven from Dissimilar Household Fibers for Air Filtration: A Proof of Concept

A proof of concept is demonstrated concerning self-charging fabrics for air filtration purposes based on common household fibers. Triboelectrically dissimilar fibers, such as wool and polyester, were interwoven into a single-layer fabric, so that local charges can be developed and partially retained at the junctions of the insulating fibers as a result of their constant frictional contact. Voluminous fibers that are typically used for knitting were chosen here, leveraging their broad availability and ease of use, so that they can be handwoven into a leak-free fabric, preventing unfiltered air to pass through directly. When tested for PM2.5 and PM10 removal, this hybrid fabric outperforms a single-material fabric made similarly from household cotton yarns. And its pressure drop and filtration efficiency were found to be in between those of a common surgical mask and a KN95 mask

Flash Reduction and Patterning of Graphite Oxide and Its Polymer Composite

Graphite oxide (GO) is a promising precursor for the bulk production of graphene-based materials due to its relatively low cost of synthesis. The superior solvent processability of GO makes it particularly attractive for making composites by premixing with other materials. Typically, the reduction of GO has relied on either chemical agents or high temperature treatment. Here we report a room temperature, chemical-free flash reduction process where a photographic camera flash instantaneously triggers the deoxygenation reaction of GO by photothermal heating. Flash irradiation also rapidly creates a fused polymer composite from a random mixture of GO and polymer particles. Using a photomask, conducting patterns such as interdigitated electrode arrays can be readily made on flexible substrates

Flash Reduction and Patterning of Graphite Oxide and Its Polymer Composite

Graphite oxide (GO) is a promising precursor for the bulk production of graphene-based materials due to its relatively low cost of synthesis. The superior solvent processability of GO makes it particularly attractive for making composites by premixing with other materials. Typically, the reduction of GO has relied on either chemical agents or high temperature treatment. Here we report a room temperature, chemical-free flash reduction process where a photographic camera flash instantaneously triggers the deoxygenation reaction of GO by photothermal heating. Flash irradiation also rapidly creates a fused polymer composite from a random mixture of GO and polymer particles. Using a photomask, conducting patterns such as interdigitated electrode arrays can be readily made on flexible substrates

Cost-effectiveness analysis of first-line pembrolizumab treatment for PD-L1 positive, non-small cell lung cancer in China

Purpose: Pembrolizumab was recently approved in several countries as a first-line treatment for patients with PD-L1 positive, non-small cell lung cancer (NSCLC). However, it is expensive. This study aimed to assess the cost-effectiveness of pembrolizumab in treating advanced NSCLC patients with PD-L1 positive cancer in China. Methods: A Markov model was developed to compare the cost-effectiveness of pembrolizumab with chemotherapy for patients with PD-L1 expression on at least 50% of NSCLC tumor cells. Model inputs for transition probabilities and toxicity were derived from published clinical trial data, while health utilities were estimated from a literature review. Costs for drugs were updated to standard fee data from West China Hospital in 2017. Health outcomes were measured in quality-adjusted life years (QALYs), and cost-effectiveness was measured as the incremental cost-effectiveness ratio (ICER). Sensitivity analyses were conducted to test the robustness of the model. Results: Pembrolizumab gained 0.45 QALYs at an incremental cost of $46,362 compared to chemotherapy for an ICER of$103,128 per QALY gained. In most scenarios, the ICER exceeded three times the Chinese Gross Domestic Product per capita. Two-way sensitivity analysis showed that, when the utility of the progression-free status increased to the maximal value of 0.845 and the 1 mg dose price decreased to $10.50, the ICER reduced to$25,216/QALY. Conclusions: Pembrolizumab is not likely to be cost-effective in the treatment of PD-L1 positive, NSCLC for Chinese patients. Less aggressive pricing may increase accessibility for patients in China.</p

Chemical Synthesis of Gold Nanowires in Acidic Solutions

Chemical Synthesis of Gold Nanowires in Acidic Solution

Dated estimate of phylogeny for species of the subgenus <i>Megabombus</i>.

<p>From Bayesian analysis of COI barcodes, using single samples selected to represent each of the species from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132358#pone.0132358.g002" target="_blank">Fig 2</a> and using the birth-death process for speciation on the tree. The tree is dated in Ma by setting the date for the divergence with the <i>Mendacibombus</i> outgroup to 34 Ma [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0132358#pone.0132358.ref033" target="_blank">33</a>]. Values at each node: posterior probability / age in Ma. Nodes with support <i>p</i>≥0.8 show 95% confidence limits for the date estimate as grey bars; nodes with support <i>p</i><0.8 have the values shown in grey; nodes with support <i>p</i><0.66 are shown collapsed. The vertical gray line show the 1.3 Ma position to distinguish between the two time periods. The extreme food specialization species name with under dashed line.</p