Influences of poly (vinyl alcohol) molecular weight and carbon nanotubes on radiation crosslinking shape memory polymers

Polyvinyl alcohol (PVA) of two molecular weights was used to prepare shape memory polymers based on chemical-crosslinking by glutaraldehyde. The chemical-crosslinking was done in the presence of 2-carboxyethyl acrylate oligomers (CEA) and nano-filler [multi-wall carbon nanotubes (MWCNT) and functionalized carbon nanotubes (MWCNT-NH2)] followed by radiation-induced crosslinking. The analysis of the material revealed an increase in the gel fraction and a significant reduction in swelling of the nanocomposite material that was crosslinked with both glutaraldehyde and ionizing radiation. The radiation crosslinked nanocomposites demonstrated approximately a 90% gelation over a range of 50–300 kGy irradiation doses. The scanning electron microscopy (SEM) analysis showed a homogeneous distribution of nanocomposites in the composite matrix. The thermal properties of radiation crosslinked (PVA/CEA) and (PVA-CEA)-nano-fillers were investigated by a thermogravimetric analysis (TGA). The mechanical properties were examined via dynamic mechanical analysis (DMA) which showed significant variation because of the addition of nanocomposites. This radiation crosslinked materials show good shape memory behavior that may be useful in many applications based on the range of temperatures at which Tan δ appears.     

New species of Primula (Primulaceae) from Utah

Named as a new species from the House Range of Millard County, Utah, as Primula domensis Kass & Welsh.     

Variation in genome-wide mutation rates within and between human families

J.B.S. Haldane proposed in 1947 that the male germline may be more mutagenic than the female germline. Diverse studies have supported Haldane's contention of a higher average mutation rate in the male germline in a variety of mammals, including humans. Here we present, to our knowledge, the first direct comparative analysis of male and female germline mutation rates from the complete genome sequences of two parent-offspring trios. Through extensive validation, we identified 49 and 35 germline de novo mutations (DNMs) in two trio offspring, as well as 1,586 non-germline DNMs arising either somatically or in the cell lines from which the DNA was derived. Most strikingly, in one family, we observed that 92% of germline DNMs were from the paternal germline, whereas, in contrast, in the other family, 64% of DNMs were from the maternal germline. These observations suggest considerable variation in mutation rates within and between families.     

A checklist of the vascular plants of the House Range, Utah

A checklist of the vascular plants of the House Range, Juab and Millard counties, Utah, is presented. A flora of 373 species and infraspecific taxa in 231 genera and 60 families are reported. The geology, physiography, climate, and plant communities are briefly discussed. Several endemics occur in the study area and a new taxon has been described.     

Microstructural evolution and intermetallic formation in Al-8wt% Si-0.8wt% Fe alloy due to grain refiner and modifier additions

An alloy of Al-8wt% Si-0.8wt% Fe was cast in a metallic die, and its microstructural changes due to Ti-B refiner and Sr modifier additions were studied. Apart from usual refinement and modification of the microstructure, some mutual influences of the additives took place, and no mutual poisoning effects by these additives, in combined form, were observed. It was noticed that the dimensions of the iron-rich intermetallics were influenced by the additives causing them to become larger. The needle-shaped intermetallics that were obtained from refiner addition became thicker and longer when adding the modifier. It was also found that α-Al and eutectic silicon phases preferentially nucleate on different types of intermetallic compounds. The more iron content of the intermetallic compounds and the more changes in their dimensions occurred. Formation of the shrinkage porosities was also observed.     

A novel mass culture ofEntamoeba histolytica on nutrient agar

Résumé Une nouvelle méthode de culture deEntamoeba histolytica etTrichomonas hominis sur plaques d'agar est employée ici avec succès.     

A PSL Ontology-based Shop Floor Dynamical Scheduler Design

Due to the complex, uncertainty and dynamics in the modern manufacturing environment, a flexible and robust shop floor scheduler is essential to achieve the production goals. A design framework of a shop floor dynamical scheduler is presented in this paper. The workflow and function modules of the scheduler are discussed in detail. A multi-step adaptive scheduling strategy and a process specification language, which is an ontology-based representation of process plan, are utilized in the proposed scheduler. The scheduler acquires the dispatching rule from the knowledge base and uses the buildin on-line simulator to evaluate the obtained rule. These technologies enable the scheduler to improve its fine-tune ability and effectively transfer process information into other heterogeneous information systems in a shop floor. The effectiveness of the suggested structure will be demonstrated via its application in the scheduling system of a manufacturing enterprise.     

含过量Fe和Si的铸态Al–Cu合金的拉伸性能和热裂敏感性

This study was undertaken to investigate the tensile properties and hot tearing susceptibility of cast Al–Cu alloys containing excess Fe (up to 1.5wt%) and Si (up to 2.5wt%). According to the results, the optimum tensile properties and hot tearing resistance were achieved at Fe/Si mass ratio of 1, where the α-Fe phase was the dominant Fe compound. Increasing the Fe/Si mass ratio above unity increased the amounts of detrimental β-CuFe platelets in the microstructure, deteriorating the tensile properties and hot tearing resistance. Decreasing the mass ratio below unity increased the size and fraction of Si needles and micropores in the microstructure, also impairing the tensile properties and hot tearing resistance. The investigation of hot-torn surfaces revealed that the β-CuFe platelets disrupted the tear healing phenomenon by blocking interdendritic feeding channels, while the α-Fe intermetallics improved the hot tearing resistivity due to their compact morphology and high melting point.