Advanced Laminated Object Manufacturing (LOM) of SiSiC Ceramics

Carbon sheets were used as a starting material for fabrication of SiSiC composites by advanced LOM. This approach consists of three steps: First a preform was fabricated form phenolic resin coated carbon paper with a LOM-device. Second the preform was turned into a carbon preform by pyrolysis in N2-atmosphere. Third pressureless reactive melt infiltration of silicon into the as fabricated carbon preform, which finally yielded a dense SiSiC composite. SEM analysis revealed a microstructure consisting of uniformly dispersed β-SiC grains in a matrix of silicon. The LOM fabricated material exhibited an average four point bending strength and Youngs modulus of 115 MPa and 165 GPa, respectively.Mechanical Engineerin

Ku Regulates the Non-Homologous End Joining Pathway Choice of DNA Double-Strand Break Repair in Human Somatic Cells

The repair of DNA double-strand breaks (DSBs) is critical for the maintenance of genomic integrity and viability for all organisms. Mammals have evolved at least two genetically discrete ways to mediate DNA DSB repair: homologous recombination (HR) and non-homologous end joining (NHEJ). In mammalian cells, most DSBs are preferentially repaired by NHEJ. Recent work has demonstrated that NHEJ consists of at least two sub-pathways—the main Ku heterodimer-dependent or “classic” NHEJ (C-NHEJ) pathway and an “alternative” NHEJ (A-NHEJ) pathway, which usually generates microhomology-mediated signatures at repair junctions. In our study, recombinant adeno-associated virus knockout vectors were utilized to construct a series of isogenic human somatic cell lines deficient in the core C-NHEJ factors (Ku, DNA-PKcs, XLF, and LIGIV), and the resulting cell lines were characterized for their ability to carry out DNA DSB repair. The absence of DNA-PKcs, XLF, or LIGIV resulted in cell lines that were profoundly impaired in DNA DSB repair activity. Unexpectedly, Ku86-null cells showed wild-type levels of DNA DSB repair activity that was dominated by microhomology joining events indicative of A-NHEJ. Importantly, A-NHEJ DNA DSB repair activity could also be efficiently de-repressed in LIGIV-null and DNA-PKcs-null cells by subsequently reducing the level of Ku70. These studies demonstrate that in human cells C-NHEJ is the major DNA DSB repair pathway and they show that Ku is the critical C-NHEJ factor that regulates DNA NHEJ DSB pathway choice

Peasant settlers and the ‘civilizing mission’ in Russian Turkestan, 1865-1917

This article provides an introduction to one of the lesser-known examples of European settler colonialism, the settlement of European (mainly Russian and Ukrainian) peasants in Southern Central Asia (Turkestan) in the late nineteenth and early twentieth centuries. It establishes the legal background and demographic impact of peasant settlement, and the role played by the state in organising and encouraging it. It explores official attitudes towards the settlers (which were often very negative), and their relations with the local Kazakh and Kyrgyz population. The article adopts a comparative framework, looking at Turkestan alongside Algeria and Southern Africa, and seeking to establish whether paradigms developed in the study of other settler societies (such as the ‘poor white’) are of any relevance in understanding Slavic peasant settlement in Turkestan. It concludes that there are many close parallels with European settlement in other regions with large indigenous populations, but that racial ideology played a much less important role in the Russian case compared to religious divisions and fears of cultural backsliding. This did not prevent relations between settlers and the ‘native’ population deteriorating markedly in the years before the First World War, resulting in large-scale rebellion in 1916

Reactive melt infiltration processing of biomorphic Si-Mo-C ceramics from wood

Different kinds of natural wood specimens (beech, pine, and rattan) were converted to biomorphic, microcellular Si-Mo-C ceramics by reactive melt infiltration processing. During processing at 1500 degrees C under vacuum the carbon of the pyrolyzed native preforms reacted with Si of the infiltrating Si-Mo eutectic melt (90.4 wt% Si). The resulting materials have fractional densities of > 90%, and contained silicon carbide (SiC), MoSi2, in addition to unreacted Si and carbon. The residual carbon remains covered by SiC. The conversion process retains the microcellular morphology of the parent wood tissue. Depending on the initial morphology of the different kinds of wood, reactive melt infiltration processing of Si-Mo-C ceramics can be used to manufacture fight weight materials with low density but adequate strength for wide ranging applications where anisotropic behavior is required

Molecular genetic classification in Prader-Willi syndrome: a multisite cohort study

BackgroundPrader-Willi syndrome (PWS) is due to errors in genomic imprinting. PWS is recognised as the most common known genetic cause of life-threatening obesity. This report summarises the frequency and further characterises the PWS molecular classes and maternal age effects.MethodsHigh-resolution microarrays, comprehensive chromosome 15 genotyping and methylation-specific multiplex ligation probe amplification were used to describe and further characterise molecular classes of maternal disomy 15 (UPD15) considering maternal age.ResultsWe summarised genetic data from 510 individuals with PWS and 303 (60%) had the 15q11-q13 deletion; 185 (36%) with UPD15 and 22 (4%) with imprinting defects. We further characterised UPD15 findings into subclasses based on the presence (size, location) or absence of loss of heterozygosity (LOH). Additionally, significantly older mothers (mean age=32.5 years vs 27.7 years) were found in the UPD15 group (n=145) compared with the deletion subtype (n=200).ConclusionsWe report on molecular classes in PWS using advanced genomic technology in the largest cohort to date. LOH patterns in UPD15 may impact the risk of having a second genetic condition if the mother carries a recessive mutant allele in the isodisomic region on chromosome 15. The risk of UPD15 may also increase with maternal age

Molecular genetic classification in Prader-Willi syndrome: a multisite cohort study.

BackgroundPrader-Willi syndrome (PWS) is due to errors in genomic imprinting. PWS is recognised as the most common known genetic cause of life-threatening obesity. This report summarises the frequency and further characterises the PWS molecular classes and maternal age effects.MethodsHigh-resolution microarrays, comprehensive chromosome 15 genotyping and methylation-specific multiplex ligation probe amplification were used to describe and further characterise molecular classes of maternal disomy 15 (UPD15) considering maternal age.ResultsWe summarised genetic data from 510 individuals with PWS and 303 (60%) had the 15q11-q13 deletion; 185 (36%) with UPD15 and 22 (4%) with imprinting defects. We further characterised UPD15 findings into subclasses based on the presence (size, location) or absence of loss of heterozygosity (LOH). Additionally, significantly older mothers (mean age=32.5 years vs 27.7 years) were found in the UPD15 group (n=145) compared with the deletion subtype (n=200).ConclusionsWe report on molecular classes in PWS using advanced genomic technology in the largest cohort to date. LOH patterns in UPD15 may impact the risk of having a second genetic condition if the mother carries a recessive mutant allele in the isodisomic region on chromosome 15. The risk of UPD15 may also increase with maternal age