SEM Analysis of Glue Behavior When Bonding Glass Structures with Complex Geometries

Bonding of glass has been studied for many years and is a mature technology today. However, the recent advances in bio-photonics and micro-fluidics, such as lab-on-a-chip devices, accentuate a need to provide reliable adhesion and sealing of components with extremely complex surface geometries. In many cases it is necessary to prevent the adhesives from leaking into microscopic channels, capillaries and holes. We present the Scanning Electron Microscopy study of adhesion of glass samples with complex surface features. Variety of adhesion conditions and procedures were tried and studied. The results demonstrate the possibility of controlled reliable adhesion and sealing without filling/obstructing the microstructures

Kinetics of Carboxylmethylation of the Charge Isoforms of Myelin Basic Protein by Protein Methyltransferase II

The charge isoforms (C1-C5) of bovine myelin basic protein (MBP) were used as substrates for the rat brain enzyme protein carboxylmethyltransferase (PM II). The objective of these experiments was to ascertain whether the kinetic behavior of the MBP isoforms reflected differences in the structures of this molecular family. Initial velocity plots as a function of the MBP-isoform concentration showed significnt differences ( p > 0.05) among the assayed isoforms except for isoforms C2 and C4. Under the conditions of our experiment all the curves exhibited a consistent sigmoidicity. The kinetic data were best fitted by a model, previously described for the enzyme D-Β-hydroxybutyrate dehydrogenase, in which two independent sites must be randomly occupied before any catalytic activity can occur. This mechanism is substantially different from that proposed by other investigators for similar PM II enzymes and other substrates. The differences in the rates of isoform carboxylmethylation are largely accounted for by the different apparent dissociation constants K s and is explained on the basis of inherent structural differences among the charge isoforms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65821/1/j.1471-4159.1989.tb09257.x.pd

Bilirubin binding to myelin basic protein, histones and its inhibition in vitro of cerebellar protein synthesis

SummaryThe binding of unconjugated bilirubin to bovine CNS myelin basic protein and to lysine and arginine rich histones has been demonstrated by means of difference spectroscopy and circular dichroism spectroscopy. This is the first demonstration of a brain specific protein that can bind bilirubin and provides a mechanism for bilirubin retention in brain as well as a mechanism for interfering with the normal acidic lipid-basic protein binding interaction. The inhibition of protein synthesis in cerebellar homogenates by bilirubin has also been demonstrated. The inhibition is about 50 per cent in the presence of 100 [mu]M bilirubin and 85 per cent in the presence of 700 [mu]M bilirubin, These results require that the current mechanisms for bilirubin neurotoxicity and cytotoxicity be expanded to include the present findings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22332/1/0000777.pd

Microcalorimetric studies of the heats of solution of bovine myelin basic protein

Heats of solution for myelin basic protein have been determined using microcalorimetry. All aqueous systems studies yielded negative heats of solution; in contrast, trifluoroethanol produced a small positive heat of solution, while reaction with dimethyl sulfoxide was strikingly exothermic. The heat of interaction for native myelin basic protein with 8 M urea at pH 4.0, 29[deg]C, was found to be -79 +/- 16 kcal/mol. The significance of these results in terms of the protein's structural organization is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25538/1/0000079.pd

Determination of the electro-optical coefficient r33 and refractive index of para-substituted poly([gamma]-benzyl--glutamate) derivatives

The electro-optical coefficient r33 and refractive index of films of poly([gamma]-benzyl--glutamate) and the p-nitro, p-fluoro and p-trifluoromethyl derivatives were determined as a way to assess the non-linear optical behaviour of these organic polymers. The p-fluoro-[gamma]-benzyl and p-trifluoromethyl-[gamma]-benzyl ester polymers are new materials synthesized for this study. The electro-optical coefficient r33 = 5.2 x 10-2 pm V-1 for the unsubstituted polymer, 13.9 x 10-2 pm V-1 for the p-nitro polymer, 3.0 x 102 pm V-1 for the p-fluoro polymer, and 1.6 x 10-2 pm V-1 for the p-trifluoromethyl polymer. The refractive indices, at a wavelength of 488 nm, of films of the polymer were determined to be 1.60, 1.61, 1.59, and 1.70, respectively, for the unsubstituted polymer and the p-nitro, p-fluoro, and p-trifluoromethyl derivatives. The frequency dependence of the dielectric constant, from 10 kHz to 4 MHz, for each of the polymer films was also determined. The waveguiding and other properties of each of the polymers were assessed in terms of the polymer structure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31855/1/0000805.pd

Studies in molecular structure, symmetry and conformation VI. Crystal and molecular structure of 1-aminocyclopentane carboxylic acid monohydrate

1-aminocyclopentane carboxylic acid monohydrate is monoclinic: space group P 2 1 / c , a = 11·24, b = 6·27, c = 11·22 Å and β = 97·6 °. The crystal structure was solved by the symbolic addition method and refined to an R factor of 12·1%. The cyclopentane ring is disordered; one of the carbon atoms exists in two alternative sites, leading to two possible conformations both of which are of the envelope type.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44835/1/10870_2005_Article_BF01245860.pd

The design of brainstem interfaces: characterisation of physiological artefacts and implications for closed-loop algorithms

Surgical neuromodulation through implantable devices allows for stimulation delivery to subcortical regions, crucial for symptom control in many debilitating neurological conditions. Novel closed-loop algorithms deliver therapy tailor-made to endogenous physiological activity, however rely on precise sensing of signals such as subcortical oscillations. The frequency of such intrinsic activity can vary depending on subcortical target nucleus, while factors such as regional anatomy may also contribute to variability in sensing signals. While artefact parameters have been explored in more ‘standard’ and commonly used targets (such as the basal ganglia, which are implanted in movement disorders), characterisation in novel candidate nuclei is still under investigation. One such important area is the brainstem, which contains nuclei crucial for arousal and autonomic regulation. The brainstem provides additional implantation targets for treatment indications in disorders of consciousness and sleep, yet poses distinct anatomical challenges compared to central subcortical targets. Here we investigate the region-specific artefacts encountered during activity and rest while streaming data from brainstem implants with a cranially-mounted device in two patients. Such artefacts result from this complex anatomical environment and its interactions with physiological parameters such as head movement and cardiac functions. The implications of the micromotion-induced artefacts, and potential mitigation, are then considered for future closed-loop stimulation methods

Re-engineering The Clinical Research Enterprise in Response to COVID-19: The Clinical Translational Science Award (CTSA) experience and proposed playbook for future pandemics

The 2020 COVID-19 pandemic has had a profound impact on the clinical research enterprises at the 60 Clinical and Translational Science Award (CTSA) Hubs throughout the nation. There was simultaneously a need to expand research to obtain crucial data about disease prognosis and therapy and enormous limitations on conducting research as localities and institutions limited travel and person-to-person contact. These imperatives resulted in major changes in the way research was conducted, including expediting Institutional Review Board review, shifting to remote interactions with participants, centralizing decision-making in prioritizing research protocols, establishing biobanks, adopting novel informatics platforms, and distributing study drugs in unconventional ways. National CTSA Steering Committee meetings provided an opportunity to share best practices and develop the idea of capturing the CTSA program experiences in a series of papers. Here we bring together the recommendations from those papers in a list of specific actions that research sites can take to strengthen operations and prepare for similar future public health emergencies. Most importantly, creative innovations developed in response to the COVID-19 pandemic deserve serious consideration for adoption as new standards, thus converting the painful trauma of the pandemic into “post-traumatic growth” that makes the clinical research enterprise stronger, more resilient, and more effective

Properties of Healthcare Teaming Networks as a Function of Network Construction Algorithms

Network models of healthcare systems can be used to examine how providers collaborate, communicate, refer patients to each other. Most healthcare service network models have been constructed from patient claims data, using billing claims to link patients with providers. The data sets can be quite large, making standard methods for network construction computationally challenging and thus requiring the use of alternate construction algorithms. While these alternate methods have seen increasing use in generating healthcare networks, there is little to no literature comparing the differences in the structural properties of the generated networks. To address this issue, we compared the properties of healthcare networks constructed using different algorithms and the 2013 Medicare Part B outpatient claims data. Three different algorithms were compared: binning, sliding frame, and trace-route. Unipartite networks linking either providers or healthcare organizations by shared patients were built using each method. We found that each algorithm produced networks with substantially different topological properties. Provider networks adhered to a power law, and organization networks to a power law with exponential cutoff. Censoring networks to exclude edges with less than 11 shared patients, a common de-identification practice for healthcare network data, markedly reduced edge numbers and greatly altered measures of vertex prominence such as the betweenness centrality. We identified patterns in the distance patients travel between network providers, and most strikingly between providers in the Northeast United States and Florida. We conclude that the choice of network construction algorithm is critical for healthcare network analysis, and discuss the implications for selecting the algorithm best suited to the type of analysis to be performed.Comment: With links to comprehensive, high resolution figures and networks via figshare.co