Rigid Structure Response Analysis to Seismic and Blast Induced Ground Motions

AbstractComprehensive studies of rigid structure responses to seismic ground excitations have been reported. It was found that the rocking and sliding response of a rigid structure is highly nonlinear. The structure stability depends on the structure slenderness, as well as the ground motion amplitude, frequency and duration. Compared to an earthquake ground motion, ground shock induced by underground or surface explosion has very large amplitude, high frequency and short duration. Moreover, vertical component of a ground shock may be substantially larger than the gravitational acceleration g. This will cause the unanchored rigid structure jump or fly into air. Therefore, the responses and stability regions of a rigid structure to blast induced ground shock will be very different from those under seismic ground motions. No study of rigid structure response to ground shock of amplitude more than 1.0g can be found in the literature. As there might be many rigid structures such as computers, document shelfs, and other important equipments in a building or a military command center close to an explosion center, understanding rigid structure response to ground shock is essential for protection of such equipments. In this study, theoretical derivation and numerical prediction of rigid structure response to ground shock are carried out. Numerical results of stability regions of rigid structures to ground shock are derived. Particular attentions are paid to the case when the vertical ground shock is more than 1.0g and the rigid structure flies into the air. Results are compared to those obtained with earthquake ground motions. Discussions on the rigid structure stability to earthquake motion and ground shock are made

Temporal Notch activation through Notch1a and Notch3 is required for maintaining zebrafish rhombomere boundaries

In vertebrates, hindbrain is subdivided into seven segments termed rhombomeres and the interface between each rhombomere forms the boundary. Similar to the D/V boundary formation in Drosophila, Notch activation has been shown to regulate the segregation of rhombomere boundary cells. Here we further explored the function of Notch signaling in the formation of rhombomere boundaries. By using bodipy ceramide cell-labeling technique, we found that the hindbrain boundary is formed initially in mib mutants but lost after 24 hours post-fertilization (hpf). This phenotype was more severe in mibta52b allele than in mibtfi91 allele. Similarly, injection of su(h)-MO led to boundary defects in a dosage-dependent manner. Boundary cells were recovered in mibta52b mutants in the hdac1-deficient background, where neurogenesis is inhibited. Furthermore, boundary cells lost sensitivity to reduced Notch activation from 15 somite stage onwards. We also showed that knockdown of notch3 function in notch1a mutants leads to the loss of rhombomere boundary cells and causes neuronal hyperplasia, indicating that Notch1a and Notch3 play a redundant role in the maintenance of rhombomere boundary

Prevalence and molecular characterization of plasmidmediated beta-lactamase genes among nosocomial Staphylococcus aureus isolated in Taiwan

Purpose: To analyze the drug susceptibility phenotypes and the patterns of plasmid-mediated β- lactamase genes among nosocomial Staphylococcus aureus drug resistance isolates in Taiwan.Methods: The antibiotic susceptibilities of 617 clinical Staphylococcus aureus isolates collected from 2005 - 2009 from Chiayi Christian Hospital (Chiayi, Taiwan) were examined in vitro against 8 antimicrobial agents using agar diffusion method. Among the clinical isolates, 114 strains of methicillinsensitive Staphylococcus aureus and 45 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolates were selected for plasmid profile analysis. The patterns of β-lactamase genes presented in plasmids were investigated by polymerase chain reaction analysis.Results: Most test strains were resistant to multiple antibiotics, particularly for the traditional agents such as ampicillin, penicillin, cephalexin and kanamycin. Plasmid profile analysis revealed that up to 36 % of the clinical strains harbored plasmids and were able to develop multi-drug resistant. Among them, most of the isolates harbored at least one plasmid (range 1 – 7) with a size range of 2.3 to 23 Kb. Among the several types of β-lactamases, blaTEM was the most prevalent.Conclusion: The results obtained from this study can serve as a valuable reference for the future control for clinical antibiotic resistant strains and more thorough discussions on resistance mechanisms.Keywords: Staphylococcus aureus, Antibiotic susceptibility, Nosocomial pathogens, Plasmid profile, β- lactamase

Učinak glicerola i glukoze na povećanje biomase, udjela lipida i topljivih ugljikohidrata u miksotrofnoj kulturi alge Chlorella vulgaris

Biodiesel-derived glycerol is a promising substrate for mixotrophic cultivation of oleaginous microalgae, which can also reduce the cost of microalgal biodiesel. The objective of this study is to investigate the potential of using glycerol and glucose as a complex carbon substrate to produce microalgal biomass and biochemical components, such as photosynthetic pigments, lipids, soluble carbohydrates and proteins by Chlorella vulgaris. The results show that C. vulgaris can utilize glycerol as a sole carbon substrate, but its effect is inferior to that of the mixture of glycerol and glucose. The effect of glycerol and glucose could enhance the algal cell growth rate, biomass content and volumetric productivity, and overcome the lower biomass production on glycerol as the sole organic carbon source in mixotrophic culture medium. The utilization of complex organic carbon substrate can stimulate the biosynthesis of lipids and soluble carbohydrates as the raw materials for biodiesel and bioethanol production, and reduce the anabolism of photosynthetic pigments and proteins. This study provides a promising niche for reducing the overall cost of biodiesel and bioethanol production from microalgae as it investigates the by-products of algal biodiesel production and algal cell hydrolysis as possible raw materials (lipids and carbohydrates) and organic carbon substrates (soluble carbohydrates and glycerol) for mixotrophic cultivation of microalgae.Glicerol dobiven iz biodizela može se upotrijebiti za uzgoj miksotrofnih mikroalgi iz kojih se proizvodi ulje, te za smanjenje troškova proizvodnje biodizela. Svrha je ovoga rada bila ispitati mogućnost primjene glicerola i glukoze u složenoj hranjivoj podlozi za uzgoj alge Chlorella vulgaris, te proizvodnju biomase i biokemijskih sastojaka, kao što su fotosintetski pigmenti, lipidi, topljivi ugljikohidrati i proteini. Rezultati potvrđuju da se alga Chlorella vulgaris može uzgojiti na glicerolu kao jedinom izvoru ugljika, iako su bolji rezultati postignuti uzgojem na podlozi s glicerolom i glukozom. Stopa rasta, prinos biomase i volumetrijska produktivnost alge povećani su primjenom podloge s glicerolom i glukozom, u usporedbi s podlogom koja sadržava samo glukozu kao organski izvor ugljika. Uporabom složene hranjive podloge može se ubrzati biosinteza lipida i topljivih ugljikohidrata (sirovina za proizvodnju biodizela i bioetanola), te usporiti sinteza fotosintetskih pigmenata i proteina. U radu je ispitana mogućnost primjene nusproizvoda dobivenih proizvodnjom biodizela i hidrolizom algi te podloga s organskim izvorima ugljika (topljivi ugljikohidrati i glicerol) kao sirovina (izvor lipida i ugljikohidrata) za proizvodnju miksotrofnih mikroalgi, radi smanjenja ukupnih troškova proizvodnje biodizela i bioetanola

Clausenain B, a phenylalanine-rich cyclic octapeptide from Clausena anisum-olens

A new cyclic octapeptide, named clausenain B, was isolated by a multi-step chromatography procedure from Clausena anisum-olens. Its structure was established as cyclo(-Phe¹-Ser-Leu¹-Phe²-Phe4-Gly-Leu²-Phe³-) (1) based on extensive spectroscopic studies and chemical evidence. Clausenain B (1) is a phenylalanine-rich cyclic octapeptide