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A new optical delivery system has been developed for the (scanning) transmission electron microscope. Here we describe the in situ and “rapid ex situ” photothermal heating modality of the system, which delivers >200 mW of optical power from a fiber-coupled laser diode to a 3.7 μm radius spot on the sample. Selected thermal pathways can be accessed via judicious choices of the laser power, pulse width, number of pulses, and radial position. The long optical working distance mitigates any charging artifacts and tremendous thermal stability is observed in both pulsed and continuous wave conditions, notably, no drift correction is applied in any experiment. To demonstrate the optical delivery system’s capability, we explore the recrystallization, grain growth, phase separation, and solid state dewetting of a Ag0.5Ni0.5 film. Finally, we demonstrate that the structural and chemical aspects of the resulting dewetted films was assessed.
From 1565 to 1570, Spain established no fewer than three networks of presidios (fortified military settlements) across portions of its frontier territories in La Florida and New Spain. Juan Pardo's network of six forts, extending from the Atlantic coast over the Appalachian Mountains, was the least successful of these presidio systems, lasting only from late 1566 to early 1568. The failure of Pardo's defensive network has long been attributed to poor planning and an insufficient investment of resources. Yet recent archaeological discoveries at the Berry site in western North Carolina—the location of both the Native American town of Joara and Pardo's first garrison, Fort San Juan—warrants a reappraisal of this interpretation. While previous archaeological research at Berry concentrated on the domestic compound where Pardo's soldiers resided, the location of the fort itself remained unknown. In 2013, the remains of Fort San Juan were finally identified south of the compound, the first of Pardo's interior forts to be discovered by archaeologists. Data from excavations and geophysical surveys suggest that it was a substantial defensive construction. We attribute the failure of Pardo's network to the social geography of the Native South rather than to an insufficient investment of resources.
Beginning with Kathleen Deagan’s description of the St. Augustine Pattern, in which domestic relations between Spanish men and Native American women contributed to a pattern of mestizaje in Spanish colonies, gender has assumed a central role in archaeological perspectives on colonial encounters. This is especially true for those encounters that accompanied colonialism in the Americas during the sixteenth through the nineteenth centuries. Gender relations were essential to the creation of new cultural identities during this time, as indigenous communities encountered immigrant, European settler groups often comprised mostly or entirely of adult men. Yet as significant as gender is for understanding how an encounter unfolded in time and space, it can be a challenge to identify and evaluate the archaeological correlates of such relations through material culture patterns. In this article, we use the related domains of food and foodways, particularly in the social context of provisioning, to evaluate how gender relations changed during the occupation of Fort San Juan de Joara (1566–1568), located at the Berry site in western North Carolina. Our research contributes to reappraisals of the St. Augustine Pattern, which posits well-defined roles for Native American women and Spanish men, by likewise situating the agency of Native American men.
Congenital abnormalities of the coronary arteries in the absence of structural heart disease account for a small but interesting percentage of cardiac lesions in children. Their presentation may vary from incidental identification to aborted/sudden cardiac death. Patients with aborted sudden death episodes will require significant support if they develop extensive ischaemic myocardial injury. Ultimately, surgical repair should be carried out as soon as haemodynamic stability is attained and the neurological status is evaluated. The aims of this article were to provide a review of congenital abnormalities of the coronary arteries most commonly seen in children in the ICU as well as to review the current critical-care management thereof.
Pore characteristics including pore size distribution, porosity, and pore
interconnectivity of PECVD SiCOH inter- layer dielectric (ILD) materials
with different dielectric constant (κ) values have been studied. Oxygen
plasma damage to SiCOH low-κ films increases dramatically as the κ value
decreases. Simulations showed that, compared to the ILD film, the overhead
dielectric films have a significant impact on the overall effective κ
(κeff) of the BEOL interconnects. Reducing the κ values of
these overhead films helps to alleviate the pressure on the κ value
requirement of the ILD materials while still meeting the κeff target. Ultra
low-κ (ULK) PECVD hydrogenated silicon carbide (H:SiC) films with a κ of 3.0
have been studied for the etch-stop applications. Studies of the chemical
composition and bonding structure suggest that less Si-C networκs are formed
and more micro-porosity are incorporated in the ULK H:SiC film. The leakage
current of the ULK H:SiC film is found to be about 5 times lower than the
H:S iC and H:SiCN films with higher κ values. The etch rate of ULK H:SiC
film using a standard SiCOH ILD etch chemistry has been found to be
negligible. Such an extremely high etch selectivity maκes these films very
good etch-stop layers.
Structural characterization of phenylacetylene dendrimers (PADs) makes it possible to explore the relationship between molecular architecture and condensed phase organization. The size and geometry of the PAD series is precisely controlled, with phenylacetylene units emanating from a central phenylene in the manner of a tridendron. The branched molecule rapidly increases in size with each synthetic generation. The “shape-persistent” nature of the phenylacetylene molecule makes it ideal for use in the construction of self-assembling supramolecular systems.
Transmission electron microscopy (TEM) has been used to identify the crystal structure of lower generation PADs, and wide-angle X-ray studies confirm the decrease in crystallinity with size. Hot stage optical microscopy studies of thermal transitions reveal melting points for lower generation PADs, and an apparent glass transition for the amorphous higher generations. This type of structural information is essential to the rational design of self-assembling materials.