The experiment was designed to operate at rotational speeds of up to 4,200 rpm with air mass flow rates of approximately 18 lbm per second. Initial tests were conducted at 2,100 rpm with ethylene as fuel. The rig was operated with different fuel injection schemes to investigate operational characteristics of the combustor. Successful combustion and pressure gain were achieved over a range of operating conditions.

The quasi-one-dimensional linear chain compound HfTe3 is experimentally and theoretically explored in the few-to single-chain limit. Confining the material within the hollow core of carbon nanotubes allows isolation of the chains and prevents the rapid oxidation which plagues even bulk HfTe3. High-resolution transmission electron microscopy combined with density functional theory calculations reveals that, once the triple-chain limit is reached, the normally parallel chains spiral about each other, and simultaneously a short-wavelength trigonal anti-prismatic rocking distortion occurs that opens a significant energy gap. This results in a sizedriven metal-insulator transition.Constraining the physical size of solids can dramatically influence their electrical, optical, magnetic, thermal, and mechanical properties. Intrinsically low-dimensional materials, including van der Waals (vdW) bonded quasi-two-dimensional compounds (exemplified by graphite, hexagonal boron nitride, and transition metal dichalcogenides (TMD)) and quasi-onedimensional compounds (exemplified by transition-metal trichalcogenides (TMT)), are particularly intriguing, in that the bulk state already presents weakened inter-plane or inter-chain bonding, which leads to strong structural, electronic, and phononic anisotropy. [1,2] Constraining the dimensions of these materials down to "atomic thinness" can result in various degrees of additional size quantization with profound consequences.Recently, the prototypical quasi-one-dimensional TMT conductor NbSe3 was successfully synthesized in the few-to single-chain limit, and unusual torsional wave instabilities were observed.[3] The driving force for the instabilities was proposed to be charging of the chains, which suggests that other TMT compounds with closely related crystal structure might exhibit similar torsional wave instabilities in the few-or single-chain limit.HfTe3 is an intriguing, but little studied, Group IV TMT with a trigonal prismatic linear chain structure very similar to that of the Group V TMT NbSe3. [4][5][6] Fig. 1 shows the quasione-dimensional crystal structure of HfTe3. Each chain distributes the Te atoms in an isosceles triangle, with the unit cell of HfTe3 containing two trigonal prismatic chains with an inversion