Novel protein crystal growth technology: Proof of concept

A technology for crystal growth, which overcomes certain shortcomings of other techniques, is developed and its applicability to proteins is examined. There were several unknowns to be determined: the design of the apparatus for suspension of crystals of varying (growing) diameter, control of the temperature and supersaturation, the methods for seeding and/or controlling nucleation, the effect on protein solutions of the temperature oscillations arising from the circulation, and the effect of the fluid shear on the suspended crystals. Extensive effort was put forth to grow lysozyme crystals. Under conditions favorable to the growth of tetragonal lysozyme, spontaneous nucleation could be produced but the number of nuclei could not be controlled. Seed transfer techniques were developed and implemented. When conditions for the orthorhombic form were tried, a single crystal 1.5 x 0.5 x 0.2 mm was grown (after in situ nucleation) and successfully extracted. A mathematical model was developed to predict the flow velocity as a function of the geometry and the operating temperatures. The model can also be used to scaleup the apparatus for growing larger crystals of other materials such as water soluble non-linear optical materials. This crystal suspension technology also shows promise for high quality solution growth of optical materials such as TGS and KDP

Fluid dynamics and low gravity effects of chemical vapor deposition

Based on the comparison between experimental data and numerical results for the growth of GaAs from TMGa, it was shown that 3D simulations are necessary to simulate rectangular CVD reactors even when operated under subcritical (Ra) conditions. The important points found are summarized in the three attached reprints. The experimental studies of mixed convection in horizontal channels have shown three regimes of high Ra (22,220) number flows. At Re = 18.5, the rolls develop very quickly, significantly modulating the axial velocity even before it reaches the beginning of the hot plate. A few centimeters downstream, the velocities become asymmetric about the vertical centerplane and at x = 12 cm, become unsteady. These asymmetries were predicted theoretically, but experimental evidence has not been published prior to this work. At Re = 36, the axial velocity is only slightly modified at x = 0. Although the flow remains steady and symmetric about the vertical centerplane, there is a small spatial oscillation in the velocities over the length of the channel. The period of this oscillation was around 5 cm. At Re = 54, the longitudinal rolls developed smoothly over a length of 30 cm, with no asymmetries, unsteadiness, or spatial oscillations. Comparison of numerical simulations of these flows to experiments has revealed the importance and difficulty of setting proper thermal boundary conditions on the sidewalls. Calculated flows and experimentally measured flows showed very similar profiles, but at different axial locations, with the rolls developing more rapidly in the experiments. This is directly attributable to partially conducting sidewalls of the apparatus being hotter in the entrance section than the adiabatic walls of the simulations. A thorough comparison of the experimental data and numerical results for a variety of sidewall boundary conditions is in preparation

GENETIC POPULATION STRUCTURE AND CONSERVATION OF BULL TROUT IN THE EAST FORK BITTERROOT RIVER DRAINAGE, MONTANA

Bull trout Salvelinus confluentus are a species of conservation interest and are currently listed as threatened by the U.S. Fish and Wildlife Service. Understanding and conserving the genetic and life history diversity of bull trout populations across their range is critical as conservation, management, and recovery plans are developed. Numerous studies in different regions have shown that local bull trout populations in close geographic proximity are typically very genetically different and evidence for dispersal among neighboring tributary populations is weak. In addition to genetic diversity, maintenance of life history diversity may increase resilience of bull trout populations. The larger migratory forms have been linked to high reproductive potential and increased population persistence in unstable environments as the distribution of adults across multiple habitats may buffer them against stochastic events. Ensuring the persistence of both genetic and life history diversity are important conservation priorities. I evaluated the genetic population structure of bull trout in the East Fork Bitterroot River, Montana and identified which tributaries produced the majority of fluvial fish using genetic assignment. My data showed that populations in tributaries are genetically distinct from each other and fish in the main stem East Fork; however, dispersal of individuals among populations was apparent suggesting a metapopulation structure. My results indicate that the scale of management for bull trout in the East Fork is the basin and that migratory fish may be important for maintaining gene flow among small populations and genetic variation within them. Given the importance of migratory fish, I examined how well we are tracking migratory bull trout populations and threats to their existence. The evaluation of the current monitoring protocol revealed that redd count surveys are not useful. Even though mark-recapture surveys are common, there are few locations where population estimates are obtained. Improving the protocols and combining approaches may improve our inference, specifically, conducting redd counts and electrofishing population estimates in areas identified as supporting migratory fish. In general, threats such as roads, grazing allotments, and wildfire have been well tracked, although future threats to river habitat conditions (e.g., temperature and degradation) and invasions of brown trout are yet to be fully evaluated

Definition study for temperature control in advanced protein crystal growth

Some of the technical requirements for an expedient application of temperature control to advanced protein crystal growth activities are defined. Lysozome was used to study the effects of temperature ramping and temperature gradients for nucleation/dissolution and consecutive growth of sizable crystals and, to determine a prototype temperature program. The solubility study was conducted using equine serum albumin (ESA) which is an extremely stable, clinically important protein due to its capability to bind and transport many different small ions and molecules

Strategies to Retain Older Workers

As the aging baby boom generation approaches retirement, employers are confronting an evertightening labor market. Defined benefit pensions have long been important source of retirement income, and many employers would like to continue offering this valuable benefit to their employees. Yet many of these plans provide strong incentives to retire early, which may not be consistent with workplace needs. In this chapter we explore options employers face when redesigning their pension plans to create positive incentives for workers to voluntarily work past traditional early retirement age. Incentives may also include work life programs such as eldercare and phased retirement, to help older workers balance their work and family responsibilities

A Virtual, Immersive, and Distributed Learning Course in Information Systems: Proposed Method and Experiment

This article proposes a cutting edge teaching method and a research agenda to test its effectiveness. A Virtual, Immersive, and Distributed Learning environment is described in detail as it relates to a study abroad in which students interact through live video while taking part in an immersive service learning project. Research methods are proposed to measure the learning effectiveness, student engagement, and student satisfaction with the course

Global Developments in Employee Benefits

The last 25 years have seen defined benefit plans increasingly been replaced by defined contribution (DC) arrangements. While the pace and shape of this change varies across countries, it is evident that we are living in a DC world. Yet the DC model is itself under challenge. The assumption of engaged consumers that accompanied the birth of DC has failed, and for both retirement and health benefits, there is a lingering question whether, in a world of low growth, stagnating incomes and increasingly diverse workforces, one-size-fits-all benefits plans can meet employees financial needs. Instead employers are increasingly expressing interest in moving to a next generation of benefits, one characterized by greater flexibility and choice, to encompass a broader range of employee needs. This paper discusses the emerging trends within occupational benefits, the forces that are driving these changes, and the challenges they pose