Green chemistry and green engineering in China: drivers, policies and barriers to innovation

With the world’s largest population and consistently rapid rates of economic growth, China faces a choice of whether it will move towards a more sustainable development trajectory. This paper identifies the different factors driving innovation in the fields of green chemistry and green engineering in China, which we find to be largely driven by energy efficiency policy, increasingly strict enforcement of pollution regulations, and national attention to cleaner production concepts, such as “circular economy.” We also identify seven key barriers to the development and implementation of green chemistry and engineering in China. They are (1) competition between economic growth and environmental agendas, (2) regulatory and bureaucratic barriers, (3) availability of research funding, (4) technical barriers, (5)workforce training, (6) industrial engineering capacity, and (7) economic and financial barriers. Our analysis reveals that the most crucial barriers to green chemistry and engineering nnovations in China appear to be those that arise from competing priorities of economic growth and environmental protection as well as the technical challenges that arise from possessing a smaller base of experienced human capital. We find that there is a great deal of potential for both the development of the underlying science, as well as its implementation throughout the chemical enterprise, especially if investment occurs before problems of technological lock-in and sunk costs emerge

Spectrally-normalized margin bounds for neural networks

This paper presents a margin-based multiclass generalization bound for neural networks that scales with their margin-normalized "spectral complexity": their Lipschitz constant, meaning the product of the spectral norms of the weight matrices, times a certain correction factor. This bound is empirically investigated for a standard AlexNet network trained with SGD on the mnist and cifar10 datasets, with both original and random labels; the bound, the Lipschitz constants, and the excess risks are all in direct correlation, suggesting both that SGD selects predictors whose complexity scales with the difficulty of the learning task, and secondly that the presented bound is sensitive to this complexity.Comment: Comparison to arXiv v1: 1-norm in main bound refined to (2,1)-group-norm. Comparison to NIPS camera ready: typo fixe

Silicon carbide, a semiconductor for space power electronics

After many years of promise as a high temperature semiconductor, silicon carbide (SiC) is finally emerging as a useful electronic material. Recent significant progress that has led to this emergence has been in the areas of crystal growth and device fabrication technology. High quality single-crystal SiC wafers, up to 25 mm in diameter, can now be produced routinely from boules grown by a high temperature (2700 K) sublimation process. Device fabrication processes, including chemical vapor deposition (CVD), in situ doping during CVD, reactive ion etching, oxidation, metallization, etc. have been used to fabricate p-n junction diodes and MOSFETs. The diode was operated to 870 K and the MOSFET to 770 K

Silicon carbide, an emerging high temperature semiconductor

In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed

Development of silicon carbide semiconductor devices for high temperature applications

The semiconducting properties of electronic grade silicon carbide crystals, such as wide energy bandgap, make it particularly attractive for high temperature applications. Applications for high temperature electronic devices include instrumentation for engines under development, engine control and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Discrete prototype SiC devices were fabricated and tested at elevated temperatures. Grown p-n junction diodes demonstrated very good rectification characteristics at 870 K. A depletion-mode metal-oxide-semiconductor field-effect transistor was also successfully fabricated and tested at 770 K. While optimization of SiC fabrication processes remain, it is believed that SiC is an enabling high temperature electronic technology

Advances in silicon carbide Chemical Vapor Deposition (CVD) for semiconductor device fabrication

Improved SiC chemical vapor deposition films of both 3C and 6H polytypes were grown on vicinal (0001) 6H-SiC wafers cut from single-crystal boules. These films were produced from silane and propane in hydrogen at one atmosphere at a temperature of 1725 K. Among the more important factors which affected the structure and morphology of the grown films were the tilt angle of the substrate, the polarity of the growth surface, and the pregrowth surface treatment of the substrate. With proper pregrowth surface treatment, 6H films were grown on 6H substrates with tilt angles as small as 0.1 degrees. In addition, 3C could be induced to grow within selected regions on a 6H substrate. The polarity of the substrate was a large factor in the incorporation of dopants during epitaxial growth. A new growth model is discussed which explains the control of SiC polytype in epitaxial growth on vicinal (0001) SiC substrates

Book review: green consumption: the global rise of eco-chic edited by Bart Barendregt and Rivke Jaffe

Green lifestyles and ethical consumption have become increasingly popular strategies in moving towards environmentally-friendly societies and combating global poverty. This book aims to scrutinize the emergent phenomenon of ‘eco-chic’: a combination of lifestyle politics, environmentalism, spirituality, beauty and health. Case studies cover Basque sheep cheese production and Ghanaian Afro-chic hairstyles to Asian tropical spa culture and Dutch fair-trade jewellery initiatives. For those interested in sustainable consumption, this book is an interesting look at the intersection of ethics, fashion, and power from a largely anthropological perspective, writes Kira Matus

Compensation in epitaxial cubic SiC films

Hall measurements on four n-type cubic SiC films epitaxially grown by chemical vapor deposition on SiC substrates are reported. The temperature dependent carrier concentrations indicate that the samples are highly compensated. Donor ionization energies, E sub D, are less than one half the values previously reported. The values for E sub D and the donor concentration N sub D, combined with results for small bulk platelets with nitrogen donors, suggest the relation E sub D (N sub D) = E sub D(O) - alpha N sub N sup 1/3 for cubic SiC. A curve fit gives alpha is approx 2.6x10/5 meV cm and E sub D (O) approx 48 meV, which is the generally accepted value of E sub D(O) for nitrogen donors in cubic SiC

Effects of Crown (carbathiin and thiabendazole), Allegiance FL (metalaxyl), Vitaflo 280 (carbathiin and thiram), and Apron Maxx (fluodioxonil and metalaxyl) on N2 fixation of chickpea, dry bean, lentil, and pea

Non-Peer Reviewe

Efficacy of Crown (carbathiin and thiabendazole) to control seed borne Ascochyta blight on kabuli chickpea

Non-Peer ReviewedAscochyta blight (Ascochyta rabiei) of chickpea (Cicer arietinum L.) is an economically important disease transmitted through the seed and stubble. In 2000, approximately 25% of the chickpea acreage in Saskatchewan was lost as a result of ascochyta blight (Pearsy, 2000). Partial resistance in ‘Sanford’, ‘Dwelley’, ‘Myles’, and ‘B90’ chickpea cultivars becomes less effective as the plant matures. The sexual stage (Didymella rabiei) has been found on chickpea residues in some regions of Saskatchewan (Chongo et al., 2000). Ascochyta infection from seed-borne inoculum occurs as scattered patches across the field and the disease spread from these patches. When infected seeds are sown, the fungus infects the seedling as it emerges and continue to sporulates on the plant until it eventually infects neighbouring plants. This disease may cause serious damage to a chickpea crop under cool and wet growing conditions, particularly at flowering and pod setting (Nene, 1984). Infected seed is presumed responsible for the introduction of the pathogen into new areas (Kaiser and Hannan, 1988). This study was conducted to determine efficacy of Crown (Carbathiin 92 g L-1 and Thiabendazole 58 g L-1) to control seed borne ascochyta blight on Kabuli chickpea