Characterization of Quantum Efficiency and Robustness of Cesium-Based Photocathodes

High quantum efficiency, robust photocathodes produce picosecond-pulsed, high-current electron beams for photoinjection applications like free electron lasers. In photoinjectors, a pulsed drive laser incident on the photocathode causes photoemission of short, dense bunches of electrons, which are then accelerated into a relativistic, high quality beam. Future free electron lasers demand reliable photocathodes with long-lived quantum efficiency at suitable drive laser wavelengths to maintain high current density. But faced with contamination, heating, and ion back-bombardment, the highest efficiency photocathodes find their delicate cesium-based coatings inexorably lost. In answer, the work herein presents careful, focused studies on cesium-based photocathodes, particularly motivated by the cesium dispenser photocathode. This is a novel device comprised of an efficiently photoemissive, cesium-based coating deposited onto a porous sintered tungsten substrate, beneath which is a reservoir of elemental cesium. Under controlled heating cesium diffuses from the reservoir through the porous substrate and across the surface to replace cesium lost to harsh conditions -- recently shown to significantly extend the lifetime of cesium-coated metal cathodes. This work first reports experiments on coated metals to validate and refine an advanced theory of photoemission already finding application in beam simulation codes. Second, it describes a new theory of photoemission from much higher quantum efficiency cesium-based semiconductors and verifies its predictions with independent experiment. Third, it investigates causes of cesium loss from both coated metal and semiconductor photocathodes and reports remarkable rejuvenation of full quantum efficiency for contaminated cesium-coated surfaces, affirming the dispenser prescription of cesium resupply. And fourth, it details continued advances in cesium dispenser design with much-improved operating characteristics: lower temperature and cleaner operation. Motivated by dispenser integration with semiconductor coatings, initial fabrication of those coatings are reported on dispenser-type substrates with measurement of quantum efficiency and analysis of thermal stability. Detailed investigations are performed on dispenser substrate preparation by ion beam cleaning and on dispenser pore structure by electron microscopy and focused ion beam milling. The dissertation concludes by discussing implications of all results for the demonstration and optimization of the future high quantum efficiency cesium dispenser photocathode

Clinical, Kinematic, and Kinetic Analysis of Knee Arthrodesis in Support of the Design of a Novel Treatment Alternative

The following body of work is the result of collaborative efforts between researchers at Clemson University and a team of practicing orthopedic surgeons. It begins with the identification of an inadequately addressed clinical need, the treatment of severe knee dysfunction, in the practices of our clinical collaborators. A case report, reviewing the condition of five affected patients, is presented to provide initial evidence for the existence of this need. A thorough review of the causes and currently available treatment options for knee dysfunction, including arthrodesis, is provided to clarify the need and establish its widespread significance, and a novel treatment model is proposed and discussed with respect to existing treatments. In spite of a large number of recently published clinical case reports, the total number of affected patients has been heretofore unreported. In order to establish this figure in further support of the need for an alternative treatment, a large database of hospital discharge records is analyzed. An estimate of the frequency of knee arthrodesis is provided, and the affected patients are characterized. Having quantified the incidence of the primary treatment method, and thus provided an estimate of the affected patient subpopulation, the effect of this treatment on lower body biomechanics is addressed. A gait analysis study was designed to simulate knee arthrodesis in normal, healthy subjects, providing a comprehensive quantification of joint kinematics and kinetics and allowing for the investigation of further hypotheses regarding the effects of treatment. In spite of a number of reported cases of mechanical failure in knee arthrodesis implant designs, the robustness of these designs against such failure has been a neglected subject in literature. Data obtained from a previously conducted gait analysis study is used to estimate the loading conditions at an immobilized knee through the construction of a computational biomechanical model. The purpose of this model is to estimate the resultant effects of knee immobilization on the musculoskeletal system during gait, and estimates of muscle and joint loading patterns are provided. Together, this knowledge is used to assist in the design and development of a novel treatment model, in the form of a salvage total knee replacement. This patent pending treatment is designed to subsume existing, less constrained treatment methods as well, broadening its applicability. It has been refined over the course of several design cycles, which were informed by the regulatory guidelines for medical device design in the United States. Prototyping techniques have been used throughout the design process to demonstrate proof of concept. This work is intended to establish the significance of an unmet clinical need, characterize the patient subset and treatment patterns affected by the need, quantify the biomechanical conditions in the bodies of affected patients, and ultimately facilitate the translation of a proposed medical device from concept to clinical use

Nickel‐Catalyzed Amination of Silyloxyarenes through C–O Bond Activation

Silyloxyarenes were utilized as electrophilic coupling partners with amines in the synthesis of aniline derivatives. A diverse range of amine substrates were used, including cyclic or acyclic secondary amines, secondary anilines, and sterically hindered primary anilines. Additionally, a range of sterically hindered and unhindered primary aliphatic amines were employed, which have previously been challenging with other classes of aryl ether electrophiles. Orthogonal couplings of silyloxyarenes with aryl methyl ethers are illustrated, where selectivity between the two C−O electrophiles is determined by ligand control, thereby allowing complementary and selective late‐stage diversification of either electrophile. Finally, a sequential coupling displays the utility of this amination method along with the reversal in intrinsic reactivity between aryl methyl ethers and silyloxyarenes.No longer just a protecting group: Silyl oxyarenes, which are commonly used as protecting groups, can function as electrophilic coupling partners in aminations using nickel catalysis. A variety of amines were utilized with a wide range of substitution patterns and functionality. The couplings are demonstrated alongside other common aryl electrophiles and were utilized in orthogonal couplings with aryl methyl ethers.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145528/1/anie201806790-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145528/2/anie201806790_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145528/3/anie201806790.pd

Nickel‐Catalyzed Amination of Silyloxyarenes through C–O Bond Activation

Silyloxyarenes were utilized as electrophilic coupling partners with amines in the synthesis of aniline derivatives. A diverse range of amine substrates were used, including cyclic or acyclic secondary amines, secondary anilines, and sterically hindered primary anilines. Additionally, a range of sterically hindered and unhindered primary aliphatic amines were employed, which have previously been challenging with other classes of aryl ether electrophiles. Orthogonal couplings of silyloxyarenes with aryl methyl ethers are illustrated, where selectivity between the two C−O electrophiles is determined by ligand control, thereby allowing complementary and selective late‐stage diversification of either electrophile. Finally, a sequential coupling displays the utility of this amination method along with the reversal in intrinsic reactivity between aryl methyl ethers and silyloxyarenes.Nicht geschützt, sondern reaktiv sind Silyloxyarene als elektrophile Kupplungspartner in nickelkatalysierten Aminierungen mit Aminen, die vielfältige Substitutionsmuster und Funktionalitäten aufweisen können. Die Kupplungen finden in Gegenwart anderer üblicher Arylelektrophile statt, und orthogonale Kupplungen mit Arylmethylethern sind möglich.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145533/1/ange201806790.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145533/2/ange201806790-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145533/3/ange201806790_am.pd

Increasing divergent thinking capabilities with music-feedback exercise

Divergent thinking is an essential aspect of creativity and has been shown to be affected both by music and physical exercise. While it has been shown that making music and physical exercise can be beneficial for Divergent Thinking in isolation, it is unclear whether the effects can be combined. The present experiment investigated the relation of physical exertion and being in control of music on Divergent Thinking and the possibility of an interaction effect. Seventy-seven predominantly young, German participants were tested with measurements of Divergent Thinking collected after either (1) physical exercise with music listening, (2) making music with a knob setup without physical effort (music control only), or (3) making physical exercise with musical feedback (Jymmin (TM)). Results showed greater increases in Divergent Thinking scores following music-feedback exercise compared to conditions of physical exercise with music listening and music control only. The data thus demonstrate that making music part of a physical exercise routine more strongly leads to the benefit of increased creative capacities, which we argue will be beneficial for athletes to prepare for certain types of competition/performance and as part of regeneration training

Unique molecular identifier-based high-resolution HLA typing and transcript quantitation using long-read sequencing

HLA typing provides essential results for stem cell and solid organ transplants, as well as providing diagnostic benefits for various rheumatology, gastroenterology, neurology, and infectious diseases. It is becoming increasingly clear that understanding the expression of patient HLA transcripts can provide additional benefits for many of these same patient groups. Our study cohort was evaluated using a long-read RNA sequencing methodology to provide rapid HLA genotyping results and normalized HLA transcript expression. Our assay used NGSEngine to determine the HLA genotyping result and normalized mRNA transcript expression using Athlon2. The assay demonstrated an excellent concordance rate of 99.7%. Similar to previous studies, for the class I loci, patients demonstrated significantly lower expression o

Copyright in China’s digital cultural industries

This chapter explores how and why copyright’s role is expanding and changing in China, focusing on recent developments in digital content markets. It considers the impact of uneven media sector reform processes on the emergence of ‘born digital’ copyright industries in China. There are signs that the commercial benefits of copyright compliance are beginning to outweigh the advantages of operating outside the intellectual property system for many Chinese stakeholders. We argue that these developments – in particular the emergence of widespread exclusive licensing practices – signal a watershed moment for China’s cultural and creative industries, highlighting the potential for digital technology to create new markets for legitimate content and services, as well as the importance of global dynamics in the development of digital era copyright industries