4 research outputs found
Modeling Hidden Nodes Collisions in Wireless Sensor Networks: Analysis Approach
This paper studied both types of collisions. In this paper, we show that advocated solutions for coping with hidden node collisions are unsuitable for sensor networks. We model both types of collisions and derive closed-form formula giving the probability of hidden and visible node collisions. To reduce these collisions, we propose two solutions. The first one based on tuning the carrier sense threshold saves a substantial amount of collisions by reducing the number of hidden nodes. The second one based on adjusting the contention window size is complementary to the first one. It reduces the probability of overlapping transmissions, which reduces both collisions due to hidden and visible nodes. We validate and evaluate the performance of these solutions through simulations
Hard Templating of Symmetric and Asymmetric Carbon Thin Films with Three-Dimensionally Ordered Mesoporosity
Sacrificial
colloidal crystal templating of porous carbon films
of tunable thickness is demonstrated using a facile thin-film assembly
and hard-template-based nanoreplication process. Convectively assembled,
colloidal crystal films composed of size-tunable silica nanoparticles
(ca. 10–50 nm) serve as scalable sacrificial scaffolds for
the formation of thickness-tunable, structurally robust, and flexible
porous carbon films. Both precursor vapor infiltration (PVI) and precursor
immersion/spin-off (PIS) techniques, suitable for replication by various
carbon sources (e.g., furfural/oxalic acid, phenol–formaldehyde,
resorcinol–formaldehyde, sucrose), result in continuous, crack-free
porous replica films. Systematic PVI-based underfilling of the template
film or PIS-based complete spin-off of excess carbon replica precursor
results in porous carbon films endowed with a symmetric three-dimensionally
ordered mesopore (3DOm) topology uniformly distributed across the
film thickness. Alternatively, by tuning the nanoparticle crystal
film thickness and the degree of overfilling (PVI) or rate of spin-off
of the carbon replica precursor (PIS), films bearing an asymmetric
structure composed of 3DOm-supported ultrathin carbon layers can be
realized. The stability of the silica templates under polymerization
and carbonization conditions helps bolster mesopore robustness within
the replica films, eliminating uniaxial pore shrinkage upon template
sacrifice. The decoupling of the template assembly and its replication
enables film formation from a wide range of carbon sources and possibly
a further expanded materials palette. Realization of porous carbon
films on various substrates without degradation of the mesostructure
is enabled by robustness of the coating/replication process to characteristic
surface roughness at scales several-fold larger than the template
particle size as well as to polymer-mediated film transfer. Among
various possible applications, we demonstrate how properties of the
symmetric 3DOm films in particular (e.g., high surface area, large
pore volume) enable their exploitation as potential low-cost alternatives
to costly Pt-based electrodes for dye-sensitized solar cell (DSSC)
technologies
Nanocasting of Carbon Films with Interdigitated Bimodal Three-Dimensionally Ordered Mesopores by Template-Replica Coassembly
Carbon
films with interdigitated bimodal three-dimensionally ordered
mesoporosity (ib3DOm) are realized by a scalable nanoreplication process
that removes the common need plaguing hard-templating strategies for
multistep prefabrication of porous sacrificial templates. Specifically,
evaporation-induced convective codeposition of size-tunable (ca. 20–50
nm) silica nanoparticles with a surrogate molecular carbon precursor
(glucose), followed by carbonization and template etching, leads to
remarkably ordered, crack-free mesoporous carbon films of tunable
thickness (ca. 100–1000 nm) and pore size. Association of the
molecular carbon precursor with the assembling pore forming particles
is found to transition the system among three distinct film morphologies
(collapsed, ib3DOm C, disordered), thereby establishing a pseudophase
behavior controlled by silica solids content and incipient glucose
concentration. Namely, a parametric window wherein ib3DOm C films
can be realized is identified, with a diffuse lower phase boundary
associated with collapsing carbon films, and a more distinct order-to-disorder
transition encountered at higher glucose concentrations. Mechanistic
insight suggests that glucose association with the lysine–silica
nanoparticle surface modulates the lattice spacing, <i>d</i>, of the periodically ordered mesopores in the coassembled films,
with the onset of the order-to-disorder transition occurring at a
critical normalized lattice spacing, <i>d</i><sub>c</sub>/<i>D</i> ∼ 1.16. This appears to apply across the
phase space associated with <i>D</i> = 50 nm silica particles
and to translate among other phase spaces associated with smaller
particles (e.g., 30 nm). We briefly demonstrate the robustness of
the codeposition process for realizing ib3DOm C films on rough FTO
glass substrates and show that, in this form, these materials hold
potential as low-cost alternatives to costly platinum electrodes for
dye-sensitized solar cells
Additional file 1: of Targeting FLT3 in acute myeloid leukemia using ligand-based chimeric antigen receptor-engineered T cells
Figure S1. Flow cytometry analysis of CD45+CD33+ leukemia cells in peripheral blood of 14 and 7 days before death of leukemia mice. Figure S2. FLT3 SFI of three cord blood CD34+ HSCs, five FLT3+ leukemia cell lines, and leukemia cells of ten AML patients were analyzed by flow cytometry. (PNG 1277 kb