Design of experiment for the optimisation of deep reactive ion etching of silicon inserts for micro-fabrication

The following paper describes a design of experiments investigation of the deep reactive of pillar structures on a silicon wafer. The etched wafers would subsequently be used as masters for the fabrication of nickel mould inserts for microinjection moulding. Undercuts occur when the pillar base has a smaller cross-section than the apex of the pillar. They therefore affect tolerances of the subsequent nickel mould, its strength and its de-mouldability from the silicon form. The response measured in these experiments was the degree of undercut of micro-scale (10 μm x 10 μm x 40 μm, 5 μm x 5 μm x 40 μm and 2 μm x 2 μm x 40 μm) The literature suggests that gas pressure, platen power, gas flow rate, phase switching times and mask size can all affect the degree of undercut. After examination of this literature, and of manufacturers guidelines, three parameters were selected for experimental testing: platen power, C 4F 8 gas flow rate during the passivation phase and switching times. Switching times was found to be the only statistically significant parameter for both 10x10 μm and 5x5 μm pillars. The 2x2 μm pillars were not successfully replicated and could therefore not undergo statistical evaluation

The value of bosses

How and by how much do supervisors enhance worker productivity? Using a company-based data set on the productivity of technology-based services workers, supervisor effects are estimated and found to be large. Replacing a boss who is in the lower 10% of boss quality with one who is in the upper 10% of boss quality increases a team’s total output by more than would adding one worker to a nine member team. Workers assigned to better bosses are less likely to leave the firm. A separate normalization implies that the average boss is about 1.75 times as productive as the average worker

The effects of Ba2+ content on depolarization temperature and pyroelectric properties of lead-free 0.94Na0.5Bi0.5TiO3-0.06Ba1+xTiO3 ceramics

Lead-free 0.94Na0.5Bi0.5TiO3–0.06Ba1+xTiO3 (NBT–0.06B1+xT) ceramics (0.0 ≤ x ≤ 0.03) were synthesized by a conventional solid-state reaction process. X-ray diffraction shows that the compositions are at the morphotropic phase boundary where rhombohedral and tetragonal phase coexist. Grain size slightly changes with the increase of Ba2+ content and reaches the minimum at x = 0.02. The depolarization temperature (Td) decreases with the extra Ba2+content but the lowest Td was obtained at x = 0.01–0.02. The pyroelectric coefficient (p) was measured as a function of Ba2+ content, and increased from 2.90 × 10−4 to 3.54 × 10−4 C m−2 °C−1, and from 55.3 × 10−4 to 740.7 × 10−4 C m−2 °C−1 for x = 0.00 and 0.02 at RT, and depolarization temperature (Td) respectively. The pyroelectric coefficient (p) shows a large increase with rising the temperature and reaches the maximum value at the depolarization temperature (Td). The figures of merits of Fi, Fv and FD have all been improved with the addition of extra barium. These improved pyroelectric properties indicate that NBT–0.06B1+xT is a promising material for pyroelectric applications or a wide range of temperature

The decrease of depolarization temperature and the improvement of pyroelectric properties by doping Ta in lead-free 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 ceramics

Ta-doped lead-free 0.94NBT-0.06BT-xTa (x=0.0–1.0%) ceramics were synthesized by a conventional solid-state route. XRD shows that the compositions are at a morphotropic phase boundary where rhombohedral and tetragonal phases coexist. The depolarization temperature (Td) shifted to lower temperature with the increase of Ta content. The pyroelectric coefficient (p) of doped ceramics greatly enhanced compared with undoped material and reached a maximum of 7.14×10−4 C m−2 °C−1 at room temperature (RT) and 146.1×10−4 C m−2 °C−1 at Td at x=0.2%. The figure of merits, Fi and Fv, also showed a great improvement from 1.12×10−10 m v−1 and 0.021 m2 C−1 at x=0.0 to 2.55×10−10 m v−1 and 0.033 m2 C−1 at x=0.2% at RT. Furthermore, Fi and Fv show the huge improvement to 52.2×10−10 m v−1 and 0.48×10−10 m v−1 respectively at Td at x=0.2%. FC shows a value between 2.26 and 2.42 ×10−9 C cm−2 °C−1 at RT at x=0.2%. The improved pyroelectric properties make NBT-0.06BT-0.002Ta ceramics a promising infrared detector material

Enhancement of pyroelectric properties of lead-free 0.94 Na 0.5 Bi 0.5 TiO 3-0.06 BaTiO 3 ceramics by La doping

Lead-free 0.94NBT-0.06BT-xLa ceramics at x = 0.0–1.0 (%) were synthesized by a conventional solid-state route. XRD shows that the compositions are at a morphotropic phase boundary where rhombohedral and tetragonal phases coexist. With increasing La3+ content pyroelectric coefficient (p) and figures of merits greatly increase; however, the depolarization temperature (Td) decreases. p is 7.24 × 10−4C m−2 °C−1 at RT at x = 0.5% and 105.4 × 10−4C.m−2 °C−1 at Td at x = 0.2%. Fi and Fv show improvements at RT from 1.12 (x = 0%) to 2.65 (x10 −10 m v−1) (x = 0.5%) and from 0.021 to 0.048 (m2.C−1) respectively. Fi and Fv show a huge increase to 37.6 × 10−10 m v−1 and 0.56 m2 C−1 respectively at Td at x = 0.2%. FC shows values of 2.10, 2.89, and 2.98 (x10−9C cm−2 °C−1) at RT at 33, 100 and 1000 (Hz) respectively. Giant pyroelectric properties make NBT-0.06BT-xLa at x = 0.2% and 0.5% promising materials for many pyroelectric application

Giant pyroelectric properties in La and Ta co-doped lead-free 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 ceramics

La and Ta co-doped Lead-free 0.94NBT-0.06BT ceramics were synthesized by a conventional solid-state route. The compositions remain at a morphotropic phase boundary. The depolarization temperature (Td) decreased with increasing doping contents. The room temperature (RT) pyroelectric coefficient (p) was highly enhanced compared with undoped material (3.15 × 10−4 C m−2 °C−1) and reached 12.9 × 10−4 C m−2 °C−1, whereas, at Td, 58.6 × 10−4 C m−2 °C−1 could be obtained rather than 23.9 × 10−4 C m−2 °C−1 for undoped materials. The pyroelectric figure of merits, Fi and Fv, also showed a huge improvement from 1.12 × 10−10 m v−1 and 0.021 m2 C−1 of undoped material to 4.61 × 10−10 m v−1 and 0.078 m2 C−1 of doped materials at RT, and to 20.94 × 10−10 m v−1 and 0.28 × 10−10 m2.C−1 at Td. RT FC values are ∼2.40, 2.46, and 2.57 (×10−9 C cm−2 °C−1) at frequency 33, 100 and 1000 (Hz) respectively, at La = Ta = 0.2%. The pyroelectric coefficient achieved at RT in this study is almost one order of magnitude higher than PZT materials, furthermore, the figure of merits of the new compositions are comparable with or even better in those of PZT materials and other lead-free ceramics. The improvement in the pyroelectric properties makes La and Ta co-doped NBT-0.06BT ceramics possible materials to replace lead-containing PZT ceramics for infrared detector materials at a wide temperature range

Characterisation of lead barium zirconate thin films for utilisation of the electrocaloric effect

Characterisation of a composition of Lead Barium Zirconate thin films deposited by a spin coating sol-gel process onto platinised silicon substrates has been undertaken to investigate a potential application utilising the reported electrocaloric properties of the material. Xray diffraction studies revealed that above 700 °C the presence of pyrochlore phase was replaced by ferroelectric phase but the identification of antiferroelectric phases previously reported could not be identified. Wet etching of the films produced an insoluble residue containing only evidence of zirconium out of the original three metals, which resembled a skeletal structure similar to the original rosette morphology of the annealed films. Elemental analysis of the annealed films using EDX indicated a non-target Pb:Ba:Zr ratio, which suggested a reduced Zr content of the films. “Solution-like” rather than “sol-like” nature of the spin coated sol and phase boundary proximity are proposed for reported observations, and a mechanism is proposed to account for the unusual observed trend in dielectric constant

Electronic Commerce Strategy in the UK Electricty Industry: The Case of Electric Co and Dataflow Software

This paper analyses the strategic business and IT response of Electric Co, a large electricity company, to deregulation and increased competition in the UK electricity industry. In common with deregulation in other markets such as North America and Australia, the UK regulator has specified strict regulations on how power generators, distribution and supply companies should interact with each other, and with business and consumer customers. In order to compete effectively Electric Co has implemented a novel dataflow solution that enables it to connect diverse internal systems to the external marketplace. An overview of changes in the market is related to the business and IT strategies of Electric Co. The link between the high-level business strategy and the actual use of IT architecture and systems is the design and management of the business processes that dictate how information is shared throughout the supply chain. The implementation of the regulator’s business process framework has been achieved through a novel use of a business process management solution. The major benefits are shown to be increased business flexibility. An outline of the broader implications of the research is given, in particular how developments in technical standards and business process management are related to communication theory and electronic markets

Social Distancing Metrics and Estimates of SARS-CoV-2 Transmission Rates: Associations between mobile telephone data tracking and R

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). In the absence of robust preventive or curative strategies, the implementation of social distancing has been a key component of limiting the spread of the virus. Methods: Daily estimates of R(t) were calculated, and compared with measures of social distancing made publicly available by Unacast. Daily-generated variables representing an overall grade for distancing, changes in distances traveled, encounters between individuals, and daily visitation, were modeled as predictors of average R value for the following week, using linear regression techniques for eight counties surrounding the city of Syracuse, NY. Supplementary analysis examined differences between counties. Results: A total of 225 observations were available across the 8 counties, with 166 meeting the Mean R(t)<3 outlier criterion for the regression models. Measurements for Distance (β=1.002, p=.001), Visitation (β=.887, p=.012), and Encounters (β=1.070, p=.001) were each predictors of R(t) for the following week. Mean R(t) drops when overall distancing grades move from D+ to C-. These trends were significant (p<.001 for each). Conclusions: Social distancing, when assessed by free and publicly available measures such as those shared by Unacast, has an impact on viral transmission rates. The Scorecard may also be useful for public messaging about social distance, in hospital planning, and in the interpretation of epidemiological models.https://deepblue.lib.umich.edu/bitstream/2027.42/155389/1/Uncast_by_R_manuscript_Final_watermarked.pdfDescription of Uncast_by_R_manuscript_Final_watermarked.pdf : Main Articl

Neurofilament heavy chain side arm phosphorylation regulates axonal transport of neurofilaments

Neurofilaments possess side arms that comprise the carboxy-terminal domains of neurofilament middle and heavy chains (NFM and NFH); that of NFH is heavily phosphorylated in axons. Here, we demonstrate that phosphorylation of NFH side arms is a mechanism for regulating transport of neurofilaments through axons. Mutants in which known NFH phosphorylation sites were mutated to preclude phosphorylation or mimic permanent phosphorylation display altered rates of transport in a bulk transport assay. Similarly, application of roscovitine, an inhibitor of the NFH side arm kinase Cdk5/p35, accelerates neurofilament transport. Analyses of neurofilament movement in transfected living neurons demonstrated that a mutant mimicking permanent phosphorylation spent a higher proportion of time pausing than one that could not be phosphorylated. Thus, phosphorylation of NFH slows neurofilament transport, and this is due to increased pausing in neurofilament movement