The linear inverse problem in energy beam processing with an application to abrasive waterjet machining

The linear inverse problem for energy beam processing, in which a desired etched profile is known and a trajectory of the beam that will create it must be found, is studied in this paper. As an example, abrasive waterjet machining (AWJM) is considered here supported by extensive experimental investigations. The behaviour of this process can be described using a linear model when the angle between the jet and the surface is approximately constant during the process, as occurs for shallow etched profiles. The inverse problem is usually solved by simply controlling dwell time in proportion to the required depth of milling, without considering whether the target surface can actually be etched. To address this, a Fourier analysis Is used to show that high frequency components in the target surface cannot be etched due to the geometry of the jet and the dynamics of the machine. In this paper, this frequency domain analysis is used to improve the choice of the target profile in such a way that it can be etched. The dynamics of the machine also have a large influence on the actual movement of the jet. It is very difficult to describe this effect because the controller of the machine is usually unknown. A simple approximation is used for the choice of the slope of a step profile. The tracking error between the desired trajectory and the real one is reduced and the etched profile is improved. Several experimental tests are presented to show the usefulness of this approach. Finally, the limitations of the linear model are studied

Position Measurements with Micro-Channel Plates and Transmission lines using Pico-second Timing and Waveform Analysis

The anodes of Micro-Channel Plate devices are coupled to fast transmission lines in order to reduce the number of electronics readout channels, and can provide two-dimension position measurements using two-ends delay timing. Tests with a laser and digital waveform analysis show that resolutions of a few hundreds of microns along the transmission line can be reached taking advantage of a few pico-second timing estimation. This technique is planned to be used in Micro-channel Plate devices integrating the transmission lines as anodes

Differential Detection of Genetic Loci Underlying Stem and Root Lignin Content in Populus

In this study, we established a comprehensive genetic map with a large number of progeny from a three-generation hybrid Populus intercross, and phenotyped the lignin content, S/G ratio and 28 cell wall subcomponents both in stems and roots for the mapping individuals. Phenotypic analysis revealed that lignin content and syringyl-to-guaiacyl (S/G) ratio using pyrolysis molecular beam mass spectroscopy (pyMBMS) varied among mapping individuals. Phenotypic analysis revealed that stem lignin content is significantly higher than that in root and the quantified traits can be classified into four distinct groups, with strong correlations observed among components within organs. Altogether, 179 coordinating QTLs were detected, and they were co-localized into 49 genetic loci, 27 of which appear to be pleiotropic. Many of the detected genetic loci were detected differentially in stem and root. This is the first report of separate genetic loci controlling cell wall phenotypes above and below ground. These results suggest that it may be possible to modify lignin content and composition via breed and/or engineer as a means of simultaneously improving Populus for cellulosic ethanol production and carbon sequestration

Continuous and Quantitative Purification of T-Cell Subsets for Cell Therapy Manufacturing Using Magnetic Ratcheting Cytometry

T-cell-based immunotherapies represent a growing medical paradigm that has the potential to revolutionize contemporary cancer treatments. However, manufacturing bottlenecks related to the enrichment of therapeutically optimal T-cell subpopulations from leukopak samples impede scale-up and scale-out efforts. This is mainly attributed to the challenges that current cell purification platforms face in balancing the quantitative sorting capacity needed to isolate specific T-cell subsets with the scalability to meet manufacturing throughputs. In this work, we report a continuous-flow, quantitative cell enrichment platform based on a technique known as ratcheting cytometry that can perform complex, multicomponent purification targeting various subpopulations of magnetically labeled T cells directly from apheresis or peripheral blood mononuclear cell (PBMC) samples. The integrated ratcheting cytometry instrument and cartridge demonstrated enrichment of T cells directly from concentrated apheresis samples with a 97% purity and an 85% recovery of magnetically tagged cells. Magnetic sorting of different T-cell subpopulations was also accomplished on chip by multiplexing cell surface targets onto particles with differing magnetic strengths. We believe that ratcheting cytometry's quantitative capacity and throughput scalability represents an excellent technology candidate to alleviate cell therapy manufacturing bottlenecks

Investigation on the thermal effects during nanometric cutting process while using nanoscale diamond tools

In this paper, large scale molecular dynamics simulations are carried out to investigate the thermal effect on nanometric cutting of copper while using a single tip and a multi-tip nanoscale diamond tool. A new concept of atomistic equivalent temperature is proposed and used to characterize the temperature distribution in the cutting zone. The results show that the cutting heat generated while using a multi-tip tool is larger than that of using a single tip tool. The local temperature is found to be higher at the inner sides of the multi-tip tool cutting edges than the outer sides. Applying centro-symmetry parameters and radius distribution function, the local annealing process and its effect on the integrity of the machined nanostructures are analyzed. It is observed that the local annealing at the machined surface can improve the surface integrity of the machined nanostructures, especially in the multi-tip diamond tool cutting process. There exists a great potential to control the thickness of residual atomic defect layer through an optimal selection of the cutting speed with designed depth of cut