No description available.

No description available.

M.S.

No / Mechanochemical chemoenzymatic peptide and amide bond formation catalysed by papain was studied by ball milling. Despite the high-energy mixing experienced inside the ball mill, the biocatalyst proved stable and highly efficient to catalyse the formation of α,α- and α,β-dipeptides. This strategy was further extended to the enzymatic acylation of amines by milling, and to the mechanosynthesis of a derivative of the valuable dipeptide L-alanyl-L-glutamine. / We thank RWTH Aachen University for support from the Distinguished Professorship Program funded by the Excellence Initiative of the German federal and state governments. EPSRC, grant no. EP/L019655/1.

The purpose of this study is to prepare a manual that will aid in the coaching and playing of volley ball in interscholastic, intramural, and amateur competition.

No description available.

No description available.

Ball Grid Array (BGA) solder joints are an array of solder alloy spheres sandwiched between package substrate and printed circuit board (PCB). These solder joints provide electrical connections and mechanical integrity to the assembly of package and PCB. Upcoming advanced packaging applications will involve heavier components, higher service temperatures and higher current densities, which will result in additional stresses on BGA joints accelerating their failure. Additionally, mismatch in the coefficient of thermal expansion (CTE) between the substrate, solder balls and PCB results in fracture near the solder-substrate interface posing a reliability risk. Moreover, higher current densities at elevated temperatures, also aggravate electromigration (EM) failure. It is important to mitigate these reliability risks associated with accelerated thermal cycling (ATC) and high current density EM. In this dissertation, various approaches to improve the ATC and EM reliability of packages have been investigated. First, BGA solder alloy composition was modified by doping Bi in the conventionally used Sn-3.0Ag-0.5Cu (SAC305) and Sn-4.0Ag-0.5Cu (SAC405) alloys to improve the mechanical strength of the solder joints. The effect of 1-3% Bi doping on aging induced changes in hardness, creep strength, tensile strength, viscoplasticity and microstructure was studied. Second, a reliability improvement measure (RIM) to mitigate fatigue failure of BGA solder joints was investigated. The microstructures of solder joints subjected to ATC were investigated for fatigue fractures and recrystallization of grains. Third, RIM measures to prevent EM failure of packages caused by high current density were investigated. The ability of novel substrate designs in prolonging time to failure of solder joints in packages along with EM failure mechanisms have been discussed. This dissertation thus provides insights on the efficacy and mechanisms of various reliability improvement measures to mitigate the ATC and EM reliability risks in BGA solder joints to guide future packaging design.

Syfte och frågeställningar Studiens syfte var att undersöka hur lärare i idrott och hälsa på gymnasiet förhåller sig till läroplanen med avseende på bollspel och bollekar. Vidare var studiens syfte att analysera och diskutera resultaten utifrån läroplansteori som teoretiskt ramverk. För att uppfylla syftet utformades följande frågeställningar: Hur arbetar lärarna med bollspel och bollekar i undervisningen? Vilka motiv uppger lärarna till att de använder bollspel och bollekar i undervisningen? Metod En kvalitativ metod användes för att besvara studiens syfte och frågeställningar och intervjuer genomfördes med sex gymnasielärare i idrott och hälsa som uppfyllde studiens kriterier. Urvalet skedde enligt bekvämlighetsprincipen. Resultat Samtliga lärare berättade att de använde sig av bollspel och bollekar i undervisningen och de uppskattade att 12 till 25 procent av tiden ägnades åt dessa aktiviteter. De vanligaste bollaktiviteterna var fotboll, badminton, basket, softboll, volleyboll och lacrosse. Lärarna använde mindre vanliga spel och lekar för att jämna ut nivåskillnader mellan elever. De använde olika bollaktiviteter för att eleverna genom dessa skulle vara fysiskt aktiva senare i livet. Lärarna berättade att de valde bollspel och bollekar efter sina egna kunskaper och färdigheter samt efter lokaler och materiel. Alla lärare använde bollspel och bollekar som en metod för att utveckla eller lära ut någonting annat än själva spelet eller leken. Samtliga lärare kopplade bollspel och bollekar till ämnesplanens centrala innehåll och de ansåg att elever kunde uppnå flera kunskapskrav genom undervisningen. Slutsats Slutsatser i studien var att bollspel och bollekar förekom i undervisningen i ämneskursen idrott och hälsa 1 men i mindre utsträckning än vad tidigare forskning har visat. Formuleringen av den nya läroplanen har haft stor del i att bollspel och bollekar har minskat. Alla lärare hade ett tydligt syfte med att använda bollspel och bollekar och kopplade dessa till ämnesplanens centrala innehåll och kunskapskrav. Det fanns likheter i lärarnas tolkningar av ämnesplanen vilket visade på att ämnets klassifikation stärkts. Lärarnas val av styrgrupp medförde att en del elever missgynnades. Lärarna måste väga för- och nackdelar mellan vanliga och mindre vanliga bollspel och bollekar mot varandra. Utifrån detta måste lärarna sedan besluta vilken aktivitet som uppfyller det tänkta syftet på bästa sätt. / Aim The purpose of the study was to examine how teachers in physical education and health on a high school level relate to the curriculum with a focus on ball games and ball exercises. Furthermore the study’s purpose was to analyze and discuss the results from curriculum theory as the theoretical framework. To fulfill this purpose the following research questions were established: How do teachers use ball games and ball exercises in their teaching? What motives do the teachers present while choosing to use ball games and ball exercises in their teaching? Method A qualitative method was used to answer the study’s purpose and research questions and interviews were conducted with six high school teachers in physical education and health that fulfilled the study’s criteria. The selection was founded on the comfort principle. Results All teachers confirmed to be using ball games or ball exercises in their teaching and they estimated that 12 to 25 percent of the curriculum were used for these specific exercises. The most common ball games were football, badminton, basketball, softball, volleyball and lacrosse. The teachers conducted less common games and exercises to even out the performance levels of different students. They varied their ball activities so that students through these exercises would be physically active later in life. The teachers told that they chose ball games and ball exercises based on their personal knowledge and access to facilities and material. All teachers used ball games and ball exercises as a method to develop or teach something other than the actual game itself. All teachers linked ball games and ball exercises to the curriculums core content and they believed that students could achieve several of the knowledge requirements through the education. Conclusion The conclusions of this study were that ball games and ball exercises were present in the education of the course physical education and health 1 but in less quantity than what earlier research has proven. The formulation of the new curriculum have had a major impact on the fact that ball games and ball exercises has decreased. All teachers had a clear purpose for using ball games and ball exercises and connected these to the curriculums core content and knowledge requirements. There were similarities between teachers interpretation of the curriculum which showed a strengthening of the subjects classification. The teacher’s selection of steering groups result in some students having a disadvantage. The teachers must weigh advantages and disadvantages between common and less common ball games and ball exercises against each other. Based on these observations the teachers must then choose which activities are best suited to successfully fulfill their purpose.

Thermosonic ball bonding is the most popular method used to create electrical interconnects between integrated circuits (ICs) and substrates in the microelectronics industry. Traditionally gold (Au) wire is used, however with industry demands for lower costs and higher performance, novel wire materials are being considered. Some of these wire materials include Cu, insulated, and coated wires. The most promising of which being Cu wire. Some of the main issues with these wire materials is their performance in the electrical flame off (EFO) step of the wire bonding process. In the EFO step a ball called the free air ball (FAB) is formed on the end of the wire. The quality of the FAB is essential for reliable and strong ball bonds. In Cu wire bonding the hardness of the FAB and oxidation are the main issues. A hard FAB requires larger bonding forces and US levels to make the bond which increases the likelihood of damage to the IC. Excessive oxidation acts as a contaminant at the bond interface and can also influence the shape of the FAB. Shielding gases are required to reduce oxidation and improve FAB quality. This thesis focuses on the EFO process and the influence of EFO parameters and shielding gases on Au and Cu FABs. The primary focus of this thesis is to provide a better understanding of the EFO process in order to expedite the introduction of novel wire materials into industry. Several different experiments are performed on an automated thermosonic wire bonder with 25 µm Au and Cu wires to investigate the EFO process during ball bonding. The effects of EFO parameters on the hardness and work hardening of FABs and the effects of shielding gas type and flow rates on the quality of the FABs are determined. The EFO discharge characteristics in different shielding gases is also studied to better understand how the composition of the atmosphere the FAB is formed in influences the energy input via the EFO electrical discharge. Using the online deformability method and Vickers microhardness testing it is found that the EFO current (IEFO) and EFO time (tEFO) have a large influence on the hardness and work hardening of Au and Cu FABs. A harder FAB produced with a large IEFO and low tEFO will work harden less during deformation. The bonded ball will be softer than that of a FAB produced with a lower IEFO and higher tEFO. The online deformability method is found to be twice as precise as the Vickers microhardness test. An online method for characterizing the quality of FABs is developed and used to identify shielding gas flow rates that produce defective FABs. The EFO process for an Au wire and two Cu wire materials is investigated in flow rates of 0.2-1.0 l/min of forming gas (5 % H2 + 95 % N2) and N2 gas. All three of the most common FAB defects are identified with this online method. It is found that good quality FABs cannot be produced above flow rates of 0.7 l/min and that H2 in the shielding gas adds a thermal component to the EFO process. It is recommended that the gas flow rate be optimized for each new wire type used. The EFO discharge power is measured to be 12 % higher in a N2 gas atmosphere than in a forming gas atmosphere. The lower ionization potential of the forming gas leads to a higher degree of ionization and therefore lower resistance across the discharge gap. It was found that the discharge power does not determine the energy transferred to the wire anode because the Au FAB produced in forming gas has a 6 % larger diameter than that of the FABs produced in N2 gas. Other factors that effect the voltage of the EFO discharge include the controlled EFO current, the discharge gap, and the wire anode material.