Synthesis and aromatisaion reactions of arene hydrates and cis-dihydrodiols

The aim of this work was to synthesis a range of substituted arene hydrates, determine their second-order rate constant for dehydration and generate a Hammett plot for comparison with other published p-values for similar carbocation-forming reactions. The first hydrate presented is the methyl benzoate hydrate (see section 2.1). A number of first order rate constants for the aromatisation (dehydration) reaction were determined in dilute perchloric acid at ionic strength 0.5 maintained with sodium perchlorate. The reaction was followed by UV-Vis spectrophotometry and (^1)H NMR spectroscopy. The second order rate constant was determined to be 9.32 X l0(^-2) М(^-1)s(^-1) which corresponds to a half-life of 7 seconds in 1M HCIO(_4). The arene hydrate of biphenyl was also synthesised (see section 2.2). The solubility issues discussed in section 2.2.2 meant the aromatisation reaction could not be followed by (^1)H NMR spectroscopy. The first order rate constants were determined in acetate and phosphate buffers, at ionic strength 0.5, maintainted with sodium Perchlorate, from pH 5 to 7. The second order rate constant was determined to be 2.11 X 10(^2) M(^-1)s(^-1) which corresponds to a half-life of 3.3 X 10(^-4)s in 1M HCIO(_4). As presented in sections 2.3-2.7, the synthetic route to the alkyl substituted hydrates gave two products - the ortho and the ipso hydrates. In the case of the ethyl substituted hydrate only the ortho hydrate was synthesised. For R = tBu, only a small proportion of the products formed was the ipso hydrate due to Its reactivity. The ortho and ipso hydrates of toluene and cumene were both synthesised. These could not be separated and so the aromatisation kinetics were followed in situ and fitted to a double exponential equation. The aromatisation reactions were followed by UV-vis spectrophotometry in acetate and phosphate buffers at 25 С and ionic strength 0.5 M, maintained with sodium perchlorate. The second-order rate constants for aromatisation for the ortho-hydrates were determined to be for R = Me, Et, iPr, tBu and are 514, 538, 642 and 949 M (^-1)s(^-1), respectively. The second-order rate constants for aromatisation for the ipso-hydrates isolated were determined to be for R = Me and iPr are 9.81x10(^3) and 1.47 X 10(^4) (^-1)s(^-1). A number of linear free energy correlations were attempted and the best correlation was found with σ(^+), this is consistent with a reaction involving a planar carbocation with through-bond stabilisation. The p-value was determined to be -6.5. The published p- value for the cis dihydrodiols, where a better correlation with Op was reported, is -8.2(^1). The magnitude of p suggests the hydrates have an earlier transition state to carbocation formation than the diols with less positive charge build-up. The computational results show that the carbocation intermediate formed during the aromatisation reaction of the hydrates is planar whereas the carbocation intermediate generated from the diols is puckered. This corroborates the results from the kinetic analysis and also the magnitude and sign of the p-values from the Hammett correlations. When the carbocation intermediate is puckered, the through-bond stabilisation is hindered and so a poor correlation with σ(^+) is observed. The rate constant for acid-catalysed isomerisation of optically active cis-indene dihydrodiol was determined. This represents the rate constant for formation of the corresponding carbocation intermediate. The second-order rate constant for carbocation formation (k(_H)) was determined by (^1)H NMR spectroscopy in concentrated perchloric acid to be 1.11 X 10(-6) M (^-1)s(^-1). This is comparable with the second-order rate constant for carbocation formation in teri-butanol which is 1.4 X 10(^-6) M(^-1)s(^-1). The rate constant for reaction of the carbocation intermediate with water k(_H20) determined using the azide- trapping technique, is 4.99 X 10(^8) s(^-1). Combining k(_H20) with k(_H) allows the (_p)K(_R) of the indene dihydrodiol carbocation to be calculated. The (_p)K(_R) was determined to be -14.6. This is greater than the (_p)K(_R) of the indanol carbocation. The effect of the adjacent hydroxyl group counteracts the stabilising effect of the benzylic substituent

Comparison of modelling techniques for milk-production forecasting

peer-reviewedThe objective of this study was to assess the suitability of 3 different modeling techniques for the prediction of total daily herd milk yield from a herd of 140 lactating pasture-based dairy cows over varying forecast horizons. A nonlinear auto-regressive model with exogenous input, a static artificial neural network, and a multiple linear regression model were developed using 3 yr of historical milk-production data. The models predicted the total daily herd milk yield over a full season using a 305-d forecast horizon and 50-, 30-, and 10-d moving piecewise horizons to test the accuracy of the models over long- and short-term periods. All 3 models predicted the daily production levels for a full lactation of 305 d with a percentage root mean square error (RMSE) of ≤12.03%. However, the nonlinear auto-regressive model with exogenous input was capable of increasing its prediction accuracy as the horizon was shortened from 305 to 50, 30, and 10 d [RMSE (%) = 8.59, 8.1, 6.77, 5.84], whereas the static artificial neural network [RMSE (%) = 12.03, 12.15, 11.74, 10.7] and the multiple linear regression model [RMSE (%) = 10.62, 10.68, 10.62, 10.54] were not able to reduce their forecast error over the same horizons to the same extent. For this particular application the nonlinear auto-regressive model with exogenous input can be presented as a more accurate alternative to conventional regression modeling techniques, especially for short-term milk-yield predictions

Precise, high-throughput production of multicellular spheroids with a bespoke 3D bioprinter

3D in vitro cancer models are important therapeutic and biological discovery tools, yet formation of multicellular spheroids in a throughput and highly controlled manner to achieve robust and statistically relevant data, remains challenging. Here, we developed an enabling technology consisting of a bespoke drop-on-demand 3D bioprinter capable of high-throughput printing of 96-well plates of spheroids. 3D-multicellular spheroids are embedded inside a tissue-like matrix with precise control over size and cell number. Application of 3D bioprinting for high-throughput drug screening was demonstrated with doxorubicin. Measurements showed that IC 50 values were sensitive to spheroid size, embedding and how spheroids conform to the embedding, revealing parameters shaping biological responses in these models. Our study demonstrates the potential of 3D bioprinting as a robust high-throughput platform to screen biological and therapeutic parameters. Significance Statement In vitro 3D cell cultures serve as more realistic models, compared to 2D cell culture, for understanding diverse biology and for drug discovery. Preparing 3D cell cultures with defined parameters is challenging, with significant failure rates when embedding 3D multicellular spheroids into extracellular mimics. Here, we report a new 3D bioprinter we developed in conjunction with bioinks to allow 3D-multicellular spheroids to be produced in a high-throughput manner. High-throughput production of embedded multicellular spheroids allowed entire drug-dose responses to be performed in 96-well plate format with statistically relevant numbers of data points. We have deconvoluted important parameters in drug responses including the impact of spheroid size and embedding in an extracellular matrix mimic on IC 50 values

Self-Doping of Gold Chains on Silicon: A New Structural Model for Si(111)5x2-Au

A new structural model for the Si(111)5x2-Au reconstruction is proposed and analyzed using first-principles calculations. The basic model consists of a "double honeycomb chain" decorated by Si adatoms. The 5x1 periodicity of the honeycomb chains is doubled by the presence of a half-occupied row of Si atoms that partially rebonds the chains. Additional adatoms supply electrons that dope the parent band structure and stabilize the period doubling; the optimal doping corresponds to one adatom per four 5x2 cells, in agreement with experiment. All the main features observed in scanning tunneling microscopy and photoemission are well reproduced.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Lett. (preprint with high quality figures available at http://cst-www.nrl.navy.mil/~erwin/papers/ausi111

Coopetition of software firms in Open source software ecosystems

Software firms participate in an ecosystem as a part of their innovation strategy to extend value creation beyond the firms boundary. Participation in an open and independent environment also implies the competition among firms with similar business models and targeted markets. Hence, firms need to consider potential opportunities and challenges upfront. This study explores how software firms interact with others in OSS ecosystems from a coopetition perspective. We performed a quantitative and qualitative analysis of three OSS projects. Finding shows that software firms emphasize the co-creation of common value and partly react to the potential competitiveness on OSS ecosystems. Six themes about coopetition were identified, including spanning gatekeepers, securing communication, open-core sourcing and filtering shared code. Our work contributes to software engineering research with a rich description of coopetition in OSS ecosystems. Moreover, we also come up with several implications for software firms in pursing a harmony participation in OSS ecosystems.Comment: This is the author's version of the work. Copyright owner's version can be accessed at https://link.springer.com/chapter/10.1007/978-3-319-69191-6_10, Coopetition of software firms in Open source software ecosystems, 8th ICSOB 2017, Essen, Germany (2017

Green economic development in Lao PDR : a Sustainability Window analysis of Green Growth Productivity and the Efficiency Gap

A novel 'Sustainability Window' (SuWi) approach is applied for simultaneous analysis of the pillars of sustainable development; social, environmental and economic, of Lao PDR. This new method employs a variety of indicators for a comprehensive and holistic analysis of sustainable development and green inclusive economy. The analysis is grounded in the assumption that economic development is required for social development, but that simultaneously development needs to be guarded or limited to protect the environment that underpins it. As all three dimensions of sustainable development are interlinked, a comprehensive analysis requires an analytical approach that is simultaneous. The analyses provide information on minimum levels of economic development that are needed to fulfil social sustainability criteria, in tandem with the maximum economic development that avoids breaching environmental sustainability criteria. If actual economic growth lies between these minima and maxima, we can interpret that development is more sustainable with respect to the relationships embodied by the selected social and environmental indicators. The main source of data is the database of the Sustainable Society Index (SSI) developed by the Sustainable Society Foundation (SSF). The indicators used by SSI have been chosen for the Sustainability Window analysis as they can be used to assess both 'weak' and 'strong' interpretations of sustainability. Weak sustainability is defined operationally as no increase in the environmental or carbon emissions intensity of the economy, while strong sustainability is defined as no increase in absolute emissions. Further, a novel Environmental Efficiency Gap analysis has been included in the Sustainability Window. This provides information about the necessary improvement in GDP production efficiency with respect to environmental emissions. Sustainability Window combined with Environmental Efficiency Gap analysis, provides critical knowledge for planners and decision makers. It provides strategic indications of how to aim for social and environmental sustainability through economic investment and growth targets. These new methods can be used in transdisciplinary research of sustainable development and can also assist in national and regional comparisons. In the case of Lao PDR, the analysis needs to be broadened for more fundamental understanding of the gaps and weaknesses. SuWi can be used to assess the sustainable development needed to address the Sustainable Development Goals by 2030. The SuWi does not provide direct policy recommendations as such, but helps to inform decision makers about the direction of development pathways towards these key goals. (C) 2018 The Authors. Published by Elsevier Ltd.Peer reviewe

40 Gbit/s asynchronous digital optical regenerator

We present the first experimental demonstration of an asynchronous digital optical regenerator at 42.67 Gbit/s. The system effectively retimes incoming asynchronous data bursts to a local clock without burst mode clock recovery and converts the signal to a desired wavelength and duty cycle

Iatrogenic encephalocele: a rare complication of vacuum extraction delivery

Vacuum extraction is a frequently used form of assisted vaginal delivery. Here we describe a child who was born by vacuum extraction delivery. Days after the birth, a frontal swelling, which was thought to be a caput succedaneum, enlarged. Imaging revealed an iatrogenic encephalocele with a large subcutaneous CSF collection. Surgical reconstruction was performed. A parasagittal dura defect was closed. There was no involvement of the superior sagittal sinus. To our knowledge, encephalocele is an infrequent complication of vacuum extraction delivery, rarely described in literature. The child had a good recovery after the operation, without neurologic deficits