Analytical and experimental studies of advanced laser cutting techniques

The goal of this thesis is to develop advanced laser cutting techniques based on experimental and theoretical treatment of laser-material interactions, assist-gas flow and combustion reactions;A two-dimensional, conductive heat transfer model based on a moving line heat-source model was investigated in combustion-assisted laser cutting of mild steel. Laser characteristics (power, absorptivity, mode), combustion reaction (combustion heat, efficiency), and material properties (thermal properties, density, thickness and melt film thickness) were correlated to accurately predict the maximum cutting speed and kerf width;Advanced laser cutting techniques which employ the dual gas-jets or the axicon-lens doublet were investigated. Compared with the conventional laser cutting technique, these innovative methods significantly improve the cutting thickness, surface finish and productivity of difficult-to-machine materials such as stainless steels, superalloys, metal matrix composites, and ceramics. The effectiveness of the dual gas-jet laser cutting technique was attributed to the oxygen gas momentum transfer from the off-axial gas-jet, which reduced the concentration of passive oxides and consequently the viscosity and the solidification temperature of the melt. The off-axial gas-jet also provided a dynamic force to remove the melt/slag more efficiently. Analytical models based on fluid-dynamics and gas momentum transfer were developed to predict the cutting speeds in coaxial and dual gas-jet assisted laser cutting of mild and stainless steels. Laser cutting using axicon-lens doublet optics showed that the cutting time on chick eggs was shortened by five times when compared to the propane torch cutting method. A simple energy balance model based on the cutting mechanisms (vaporization and decomposition of egg shell) was used to predict the cutting and drilling time and the results agreed well with the experimental data;The standard laser cutting of polymers is often accompanied by charring and material degradation at the cut edges. A new experimental approach utilizing SF[subscript]6 plasma for effective polishing of cut surface during laser cutting of polymers was investigated. The plasma formation through the absorption of laser energy and dissociation of SF[subscript]6 and its effects on the surface finish of thermoplastic polymers including polyvinylchloride, polyamide, polypropylene and polyethylene were presented and discussed. (Abstract shortened with permission of author.

Examining the Business-Technology Alignment in Government Agencies: A Study of Electronic Record Management Systems in Taiwan

For e-government to succeed, government agencies must manage their records and archives of which the sheer volume and diversity necessitate the use of electronic record management systems (ERMS). Using an established business–technology alignment model, we analyze an agency’s strategic alignment choice and examine the outcomes and agency performance associated with that alignment. The specific research questions addressed in the study are as follows: (1) Do strategic alignment choices vary among agencies that differ in purpose or position within the overall government hierarchy? (2) Do agencies’ alignment choices lead to different outcomes? and (3) Does performance in implementing, operating, and using ERMS vary among agencies that follow different alignment choices? We conducted a large-scale survey study of 3,319 government agencies in Taiwan. Our data support the propositions tested. Based on the findings, we discuss their implications for digital government research and practice

Real-time bioprocess and automated feed control with in-line Raman sensor

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Impacts of Light Rail Transit Tram on the Voltage and Unbalance of the Distribution System

This paper presents the three-phase voltage and unbalance analysis for the distribution system with the loading of a light rail transit (LRT) tram. To investigate the dynamic responses of the system voltage and current, this paper adopts the Alternative Transients Program (ATP) software to model and simulate a multigrounded four-wire distribution system with an LRT loading. Two different definitions about unbalance are used to evaluate the problem. In this paper, the traction supply substation (TSS) with a single-phase transformer configuration is designed first for providing the electric power to the trams of LRT. However, it may result in the significant neutral line current and unbalance phenomenon to deteriorate the power quality of the distribution system. A Le-Blanc connection transformer in the TSS is therefore proposed to solve the problems

THE STRATEGIC CO-ALIGNMENT FOR IMPLEMENTING INFORMATION SYSTEMS IN E-GOVERNMENT

Regulating agency in government, i.e. regulator, must co-align its information systems (IS) planning strategy with executing agencies, i.e. executors, for better e-government performance. Using an established strategic co-alignment model, we analyze the mutual participating strategies between regulator and executors and examine the outcomes and performance associated with that co-alignment choice. After conducting a large-scale survey study of government agencies in Taiwan, the co-alignment relationship between e-government IS policy regulator and executor is examined. Based on the findings, we discuss their implications for e-government research and practice

FAM129B, an antioxidative protein, reduces chemosensitivity by competing with Nrf2 for Keap1 binding.

BackgroundThe transcription factor Nrf2 is a master regulator of antioxidant response. While Nrf2 activation may counter increasing oxidative stress in aging, its activation in cancer can promote cancer progression and metastasis, and confer resistance to chemotherapy and radiotherapy. Thus, Nrf2 has been considered as a key pharmacological target. Unfortunately, there are no specific Nrf2 inhibitors for therapeutic application. Moreover, high Nrf2 activity in many tumors without Keap1 or Nrf2 mutations suggests that alternative mechanisms of Nrf2 regulation exist.MethodsInteraction of FAM129B with Keap1 is demonstrated by immunofluorescence, colocalization, co-immunoprecipitation and mammalian two-hybrid assay. Antioxidative function of FAM129B is analyzed by measuring ROS levels with DCF/flow cytometry, Nrf2 activation using luciferase reporter assay and determination of downstream gene expression by qPCR and wester blotting. Impact of FAM129B on in vivo chemosensitivity is examined in mice bearing breast and colon cancer xenografts. The clinical relevance of FAM129B is assessed by qPCR in breast cancer samples and data mining of publicly available databases.FindingsWe have demonstrated that FAM129B in cancer promotes Nrf2 activity by reducing its ubiquitination through competition with Nrf2 for Keap1 binding via its DLG and ETGE motifs. In addition, FAM129B reduces chemosensitivity by augmenting Nrf2 antioxidative signaling and confers poor prognosis in breast and lung cancer.InterpretationThese findings demonstrate the important role of FAM129B in Nrf2 activation and antioxidative response, and identify FMA129B as a potential therapeutic target. FUND: The Chang Gung Medical Foundation (Taiwan) and the Ministry of Science and Technology (Taiwan)

Critical quality attributes (CQAs) of a therapeutic antibody produced from integrated continuous bioprocessing

The integrated continuous bioprocess provides an innovative way to produce protein drugs with flexibility and efficiency. However, during the long-term cultivation and complicated production, how to ensure the process stability and product quality is critically important. In this study, the monoclonal antibody (mAb) was produced in a bioreactor operated in a perfusion mode utilizing the ATF cell retention system for up to 32 days. The 2L harvest per day starting at day 10 was continuously purified using the 3-column periodic counter-current (PCC) chromatography system. The first protein A capture purification was performed with the dynamic binding capacity of 50% breakthrough around 60 mg mAb/mL of resin (vs 20 mg/mL resin for batch purification) for 120 cycles or 360 column operations followed by a polishing step of mixed mode chromatography for 20 cycles. The process and quality attributes were monitored daily. The results demonstrate consistency in both the purification process and the mAb qualities (in the aspects of product integrity, aggregates, and glycan profile) between PCC and batch purifications. Culture-related charge heterogeneity was observed accompanied by an increase of bioreactor harvest time using both batch and PCC purification processes. In addition, the impurities such as endotoxin and HCP were also monitored while under this high capacity utilization of chromatography resins. By sharing the insights of process and quality attributes, we hope to provide better understanding on the process-related heterogeneity between batch and continuous production and/or purification