Flatness optimization of micro-injection moulded parts: The case of a PMMA microfluidic component

Micro-injection moulding (µ-IM) has attracted a lot of interest because of its potential for the production of low-cost, miniaturized parts in high-volume. Applications of this technology are, amongst others, microfluidic components for lab-on-a-chip devices and micro-optical components. In both cases, the control of the part flatness is a key aspect to maintaining the component's functionality. The objective of this work is to determine the factors affecting the flatness of a polymer part manufactured by µ-IM and to control the manufacturing process with the aim of minimizing the in-process part deformation. As a case study, a PMMA microfluidic substrate with overall dimensions of 10 mm diameter and 1 mm thickness was investigated by designing a µ-IM experiment having flatness as the experimental response. The part flatness was measured using a micro-coordinate measuring machine. Finite elements analysis was also carried out to study the optimal ejection pin configuration. The results of this work show that the control of the µ-IM process conditions can improve the flatness of the polymer part up to about 15 µm. Part flatness as low as 4 µm can be achieved by modifying the design of the ejection system according to suggested guideline

Picophytoplankton photoacclimation and mixing in the surface oceans

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1995.Includes bibliographical references.by Jeffrey A. Dusenberry.Ph.D

The Texas Press and the Filibusters of the 1850s: Lopez, Carvajal, and Walker

The decade of the 1850s saw the Texas press separate into two opposing groups on the issue of filibustering. The basis for this division was the personal beliefs of the editors regarding the role filibustering should have in society. Although a lust for wealth drove most filibusters, the press justified territorial expansion along altruistic lines. By 1858, however, a few newspapers discarded this argument and condemned filibusters as lawless bands of ruffians plundering peaceful neighbors. Throughout the decade, the papers gradually drifted from a consensus in 1850 to discord by the date of William Walker's third attempt on Nicaragua in 1858

Transition from Contraction to Extension in the Northeastern Basin and Range: New Evidence from the Copper Mountains, Nevada

New mapping, structural analysis, and 40Ar/39Ar dating reveal an unusually well‐constrained history of Late Eocene extension in the Copper Mountains of the northern Basin and Range province. In this area, the northeast‐trending Copper Creek normal fault juxtaposes a distinctive sequence of metacarbonate and granitoid rocks against a footwall of Upper Precambrian to Lower Cambrian quartzite and phyllite. Correlation of the hanging wall with footwall rocks to the northwest provides an approximate piercing point that requires 8–12 km displacement in an ESE direction. This displaced fault slice is itself bounded above by another normal fault (the Meadow Fork Fault), which brings down a hanging wall of dacitic to rhyolitic tuff that grades conformably upward into conglomerate. These relationships record the formation of a fault‐bounded basin between 41.3 and 37.4 Ma. The results are consistent with a regional pattern in which volcanism and extension swept southward from British Columbia to southern Nevada from Early Eocene to Late Oligocene time. Because the southward sweep of volcanism is thought to track the steepening and foundering of the downgoing oceanic plate, these results suggest that the crucial mechanisms for the onset of regional extension were probably changes in plate boundary conditions coupled with convective removal of mantle lithosphere and associated regional magmatism and lithospheric weakening. Paleobotanical data indicate that surface elevations in northeastern Nevada were not significantly different than at present, suggesting that gravitational instability of overthickened continental crust was not the dominant force driving the onset of crustal thinning in mid‐Tertiary time

Synchrotron study of poly[[di-μ-aqua­(μ-2,2′-bipyridyl-5,5′-dicarboxyl­ato)di­potassium] dihydrate]

The title compound, {[K2(C12H6N2O4)(H2O)2]·2H2O}n, forms a three-dimensional coordination polymer in the solid state. The asymmetric unit consists of one K+ ion, half of a 2,2′-bipyridyl-5,5′-dicarboxyl­ate ligand, one coordinated water mol­ecule and one solvent water mol­ecule. The K+ ion is 7-coordinated by the oxygen atoms of two water mol­ecules and by five oxygen atoms of four carboxyl­ate groups, one of which is chelating. The extended structure can be described as a binodal network in which each K+ is a six-connected node, bonding to four carboxyl­ate groups and two bridging water mol­ecules, and the 2,2′-bipyridyl-5,5′-dicarboxyl­ate linkers are eight-connected nodes, with each carboxyl­ate group bridging four metal centers. Overall, this arrangement generates a complex network with point symbol {34.412.512}{34.44.54.63}2. Both of the bridging water mol­ecules participate as donors in hydrogen-bonding inter­actions; one to solvent water mol­ecules and a second to an oxygen atom of a carboxyl­ate group

Affective-Cognitive Behavioral Therapy for Fibromyalgia: A Randomized Controlled Trial

A randomized controlled trial was conducted to assess the efficacy of an individually administered form of cognitive behavioral treatment for fibromyalgia. In an additive design, 76 patients diagnosed with fibromyalgia were randomly assigned to either the experimental treatment (affective-cognitive behavioral therapy, 10 individual sessions, one per week) administered concurrently with treatment-as-usual or to an unaugmented treatment-as-usual condition. Statistical analysis conducted at the end of treatment (3 months after the baseline assessment) and at a followup (9 months after the baseline assessment) indicated that the patients receiving the experimental treatment reported less pain and overall better functioning than control patients, both at posttreatment and at followup. The implications of these findings for future research are discussed

Preliminary Assessment of Nonfuel Minerals on the Texas Continental Shelf

As part of a passive continental margin with a long depositional history, the Texas continental shelf has been richly endowed with mineral resources. Exploitation of oil and gas resources on the shelf extends back decades, and the economic value of these deposits has long been recognized. The depositional setting that made the Texas offshore so rich in hydrocarbons has left it barren of exotic nonfuel minerals such as those found in active tectonic settings near Hawaii and at the Juan de Fuca Ridge along the Pacific Northwest. Nonetheless, there are significant accumulations of potentially economic nonfuel minerals in the Texas Exclusive Economic Zone (EEZ). The most promising of these are sand and gravel deposited on the continental shelf during the sea-level fluctuations of the late Pleistocene and Holocene. Requirements for sand and gravel, created by the burgeoning Texas coastal population and the need for compatible sands for beach nourishment projects, such as those contemplated for rapidly eroding beaches at North Padre Island, the Brazos delta, and Galveston Island, combined with the depletion of nearby onshore sand and gravel resources, could make shelf mining operations economically feasible in the future. Before economic feasibility can be determined, however, the local, size, and character of potentially economic shelf deposits must be assessed.Bureau of Economic Geolog

Testing of Milliwatt Power Source Components

A milliwatt power source (MPS) has been developed to satisfy the requirements of several potential solar system exploration missions. The MPS is a small power source consisting of three major components: a space qualified heat source (RHU), a thermopile (thermoelectric converter or TEC) and a container to direct the RHU heat to the TEC. Thermopiles from Hi-Z Technology, Inc. of San Diego and the Institute of Thermoelectricity of Chernivtsi Ukraine suitable for the MPS were tested and shown to perform as expected, producing 40 mW of power with a temperature difference of about 170°C. Such thermopiles were successfully life tested for up to a year. A MPS container designed and built by Swales Aerospace was tested with both a TEC simulator and actual TEC. The Swales unit, tested under dynamic vacuum, provided less temperature difference than anticipated, such that the TEC produced 20 mW of power with heat input equivalent to a RHU