In the current study, carbon nanofibers (CNFs) were grown on a carbon fiber (CF) surface by using the chemical vapor deposition method (CVD) and the influences of some parameters of the CVD method on improving the mechanical properties of a polypropylene (PP) composite were investigated. To obtain an optimum surface area, thickness, and yield of the CNFs, the parameters of the chemical vapor de...

Aligned one-dimensional carbon nanostructures with different morphologies such as carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been synthesized by the plasma-enhanced chemical vapor deposition method with different catalyst/underlayer combinations. The electronic structures of CNTs and CNFs have been studied by X-ray absorption near-edge structure spectroscopy (XANES), which reveal...

The NP-hard problem of finding the largest renamable Horn sub-CNF of a given CNF is considered, and a polynomial time approximation algorithm is presented for this problem. It is shown that for cubic CNFs this algorithm has a guaranteed performance ratio of 40 67 .

We report experimental evidence showing a direct correlation between the alignment of carbon nanofibers ~CNFs! prepared by plasma-enhanced chemical-vapor deposition and the location of the catalyst particle during CNF growth. In particular, we find that CNFs that have a catalyst particle at the tip ~i.e., growth proceeds from the tip! align along the electric-field lines, whereas CNFs with the ...

OF THE DISSERTATION Circuits, CNFs, and Satis ability

It is a wellknown fact that the satisfiability problem (SAT) for Boolean formulas in a conjunctive normal form (CNF) is NP complete, i.e. Σ1 complete. It is also known that the decision version of Boolean minimization for CNF inputs is Σ2 complete. On the other hand there are several subclasses of CNFs (e.g. Horn CNFs) for which SAT is known to be in P = Σ0 while the minimization problem is Σ1 ...

We present new complexity results on the compilation of CNFs into DNNFs and OBDDs. In particular, we introduce a new notion of width, called CV-width, which is specific to CNFs and that dominates the treewidth of the CNF incidence graph. We then show that CNFs can be compiled into structured DNNFs in time and space that are exponential only in CV-width. Not only does CV-width dominate the incid...

In an effort to develop better orthopedic implants, osteoblast (bone-forming cells) adhesion was determined on microscale patterns (30 microm lines) of carbon nanofibers placed on polymer substrates. Patterns of carbon nanofibers (CNFs) on a model polymer (polycarbonate urethane [PCU]) were developed using an imprinting method that placed CNFs in selected regions. Results showed the selective a...

The authors present scanning transmission electron microscopy STEM of carbon nanofibers CNFs on a bulk substrate using conventional scanning electron microscopy SEM without specimen thinning. By utilizing the electron beam tilted 85° from the substrate normal, bright-field STEM contrast is obtained for the CNFs on substrate with conventional SEM. Analysis of the observed contrast using Monte Ca...