Syntheses of elusive unsaturated silacycles

In an attempt to stabilize a silicon carbon (p-p)(pi) bond by incorporating it into a benzenoid framework, it was found that the gas phase pyrolysis of 1-allyl-1-methyl-1-silacyclohexa-2,4-diene resulted in the formation of 1-methyl-1-silabenzene. In the presence of acetylenes, 1-methyl-1-silabenzene affords the 4+2 Diels-Alder adduct. In the absence of added traps, 1-methyl-1-silabenzene dimerizes in a 4+2 Diels-Alder fashion;The thermolysis of 4-allyl-4-methyl-4-silacyclopentene afforded the dimer of 1-methylsilole, the first C-unsubstituted silole. The monomeric species was generated and trapped in situ from the thermolysis of the 1-methylsilole dimer. The first isolation of a C-unsubstituted silole, 1,1-dimethylsilole, was achieved with the thermolysis of 5-benzoyloxy-3,3-dimethyl-3-silacyclopentene. At elevated temperatures and in the absence of added traps, it was found that 1,1-dimethylsilole dimerizes in a 4+2 Diels-Alder fashion. This dimer was shown to undergo a thermal retro Diels-Alder to provide an in situ source of monomeric silole;Vacuum pyrolysis of either allylcyclopentadienyldimethylsilane or 5-trimethylsilyl-5-dimethylmethoxysilylcyclopentadiene affords 6,6-dimethyl-6-silafulvene. In the absence of added traps, a dimer arising from an initial head-to-tail dimerization followed by two 1,5 silyl migrations is obtained;A beta elimination of trimethylmethoxysilane to generate a silicon-carbon double bond was extended to the syntheses of siletenes. Vacuum pyrolysis of 1,3-bis(trimethylsilyl)-3-dimethmethoxysilylpropene afforded 1,1-dimethyl-4-trimethylsilyl-1-silacyclobutene. Likewise, the thermolysis of 1,3-bis(trimethylsilyl)-3-dimethoxymethylsilylpropene was shown to afford 1-methoxy-1-methyl-4-trimethylsilyl-1-silacyclobutene;In the course of the preparation of silacycloheptatriene, it was found that 4,4-dimethyl-4-silaheptadial undergoes cyclization of 5,5-dimethyl-5-silacycloheptene with titanium metal. Further unsaturation to a silacycloheptadiene was achieved. It was also found that 1,1-dimethyl-4-trimethylsilyl-7,7-dichloro-1-silabicyclo(4.1.0)hept-2-ene underwent ring expansion to 3-chloro-1,1-dimethylsilepin under the influence of fluoride ion, although in low yields

Resilience of New Zealand indigenous forest fragments to impacts of livestock and pest mammals

A number of factors have combined to diminish ecosystem integrity in New Zealand indigenous lowland forest fragments surrounded by intensively grazed pasture. Livestock grazing, mammalian pests, adventive weeds and altered nutrient input regimes are important drivers compounding the changes in fragment structure and function due to historical deforestation and fragmentation. We used qualitative systems modelling and empirical data from Beilschmiedia tawa dominated lowland forest fragments in the Waikato Region to explore the relevance of two common resilience paradigms – engineering resilience and ecological resilience – for addressing the conservation management of forest fragments into the future. Grazing by livestock and foraging/predation by introduced mammalian pests both have direct detrimental impacts on key structural and functional attributes of forest fragments. Release from these perturbations through fencing and pest control leads to partial or full recovery of some key indicators (i.e. increased indigenous plant regeneration and cover, increased invertebrate populations and litter mass, decreased soil fertility and increased nesting success) relative to levels seen in larger forest systems over a range of timescales. These changes indicate that forest fragments do show resilience consistent with adopting an engineering resilience paradigm for conservation management, in the landscape context studied. The relevance of the ecological resilience paradigm in these ecosystems is obscured by limited data. We characterise forest fragment dynamics in terms of changes in indigenous species occupancy and functional dominance, and present a conceptual model for the management of forest fragment ecosystems

Investigating Possible Synergies in Intermodal Operations With Truck and Rail

As the trucking industry continues to examine ways to provide better service at lower cost, many companies are more heavily utilizing intermodal (IM) strategies between truck and rail, especially for those loads that are relatively non-critical in terms of delivery time requirements and that have longer lengths of haul. As IM business grows, supporting dray infrastructure naturally develops around IM rail yards. What is unknown is whether it is best to have a dedicated set of drivers performing dray operations or if efficiency and cost savings can result when utilizing a joint driving fleet to concurrently support IM and traditionally dispatched truckload freight transportation. This paper describes a set of experiments utilizing a comprehensive discrete-event system simulation model and historical data from J.B. Hunt Transport to determine whether or not operating synergies exist when IM dray operations are integrated with local, regional, and long-haul trucking operations. Performance metrics of interest to drivers, customers, and trucking companies are utilized to ensure that the research addresses issues of importance to all constituencies. The results show that there is a trade-off between different performance variables when combining operations, but that generally speaking synergies do exist when considering the needs of professional drivers. Results are more mixed with respect to the needs of carriers and customers, but the authors reach the conclusion that the positive aspects of combining OTR and IM dispatching activities outweigh the negative. Because the evaluative simulation model itself is considered to be a major contribution, it is also described in some detail herein

Effect of oil palm sustainability certification on deforestation and fire in Indonesia.

Many major corporations and countries have made commitments to purchase or produce only "sustainable" palm oil, a commodity responsible for substantial tropical forest loss. Sustainability certification is the tool most used to fulfill these procurement policies, and around 20% of global palm oil production was certified by the Roundtable on Sustainable Palm Oil (RSPO) in 2017. However, the effect of certification on deforestation in oil palm plantations remains unclear. Here, we use a comprehensive dataset of RSPO-certified and noncertified oil palm plantations (∼188,000 km2) in Indonesia, the leading producer of palm oil, as well as annual remotely sensed metrics of tree cover loss and fire occurrence, to evaluate the impact of certification on deforestation and fire from 2001 to 2015. While forest loss and fire continued after RSPO certification, certified palm oil was associated with reduced deforestation. Certification lowered deforestation by 33% from a counterfactual of 9.8 to 6.6% y-1 Nevertheless, most plantations contained little residual forest when they received certification. As a result, by 2015, certified areas held less than 1% of forests remaining within Indonesian oil palm plantations. Moreover, certification had no causal impact on forest loss in peatlands or active fire detection rates. Broader adoption of certification in forested regions, strict requirements to avoid all peat, and routine monitoring of clearly defined forest cover loss in certified and RSPO member-held plantations appear necessary if the RSPO is to yield conservation and climate benefits from reductions in tropical deforestation

Recombinant luciferase-expressing human cytomegalovirus (CMV) for evaluation of CMV inhibitors

Recombinant Towne CMV expressing luciferase under the control of CMV-DNA polymerase (POL) or the late pp28 (UL99) promoters were evaluated for potential application in high-throughput screening of anti-viral compounds. POL-and pp28-luciferase displayed maximal expression 48 and 72 hours post infection, respectively. The pp28-luciferase virus achieved a wider dynamic range of luciferase expression (6-7 logs) and was selected for testing of inhibition by five anti-viral compounds. Luciferase expression highly correlated with plaque reduction and real-time PCR. The pp28-luciferase reporter system is rapid, reproducible, and highly sensitive. It may be applied to screening of novel anti-CMV compounds

Promoting Faculty Development with ASEE/NASA Fellowship Programs- Parametric Study of Laser Beam Cutting (LBC) processes- A Case Study

American Society for Engineering Education (ASEE) and National Aeronautics and Space Administration (NASA) offer a joint program for faculty and research development. This program known as ASEE/NASA Faculty Fellowship program offers opportunities for professional development for Engineering Technology faculty. This paper discusses one such experience involving applied research at NASA Langley Research Center, which resulted in professional development of the faculty member while enhancing the undergraduate curriculum in Engineering Technology

Wildlife linkages: volumes and values of residual timber in riparian zones in eastern Texas

In regenerating southern pine, maintenance of riparian zones (RZs) is a major land concession for soil and water protection and wildlife habitat enhancement. However, there are few data quantifying the volume and value of residual timber in such areas. We inventoried merchantable timber in nine RZs of three widths in sapling-class East Texas pine plantations. Present, discounted, and projected volumes and values of residual timber were determined. Average per-acre volumes of narrow, medium, and wide RZs were 337, 1438, and 2542 board feet (Doyle log rule) and 4.6, 8.2, and 7.2 cords, respectively. At US $154.00 and US$57.00 per thousand board feet for pine and hardwood saw timber, respectively, and US $15.00 and US$5.00 per cord for pine and hardwood pulpwood, respectively, average present per-acre values were US $46.41, US$209.93 and US $352.75 for narrow, medium, and wide RZs. Interest rates for the growth of trees from 1981 to 1989 ranged 3.7$4.52, US $20.46, and US$34.38, respectively. Stumpage values at the time of harvest projected at 7% compound interest for 30 years ranged US $10.66-US$3547.54 per acre and for 80 years ranged US $313.93-US$104 499.95 per acre. The impact of these results on wildlife is discusse

Digital Transformation in the Automotive Supply Chain

In this paper, we begin the process of developing practice-based research problems and questions concerning supply chain digitalization in the automotive industry. Specifically, our focus is on understanding organizational conditions facilitating supply chain and production digitalisation and its role in performance improvement. Therefore, as a first step we organized a research workshop during last year’s Cambridge Center for International Manufacturing (CIM) Symposium with 30 executives representing multiple tiers of the automotive supply chain. The purpose was identifying key themes and patterns amongst these themes, which provides a basis for a practitioner-based, impact led research agenda. We presented the executives with ten digital scenarios developed by CIM, and recorded responses their responses to each scenario in a template of the ten scenarios. Using social network analysis (SNA) we then interrogated the qualitative data to identify: “inter-codal” patterns, linkages and relationships

Use of Near-Infrared Spectroscopic Analysis of Second Trimester Amniotic Fluid to Assess Preterm Births

This pilot study investigated the possibility that metabolomic differences exist in second trimester of women delivering at term (≥37 weeks, n = 216) and preterm (≤35 weeks, n = 11). For this retrospective study, biobanked AF samples underwent near-infrared (NIR) spectral analysis using wavelengths from 700 to 1050 nm. Spectral data was compressed then optimized by multilinear regression to create a calibration model. The resultant model was able to classify term and preterm births based on differing AF metabolomic profiles with a sensitivity and specificity of 100%. When groups were classified using a prematurity index (PI), there was a statistical difference (P < 0.001) between the predicted preterm group (PI 0.77 ± 0.08) and the term group (PI 1.00 ± 0.02). In conclusion, the 2nd trimester AF samples showed distinct differences in metabolomic profiles between patients delivering preterm as compared to those at term in functional groups related to proteins, carbohydrates, fats, polyols, and water