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Casing while drilling (CwD) technology is designed to reduce drilling time and expenses by improving the wellbore stability, fracture gradient, and formation damage while reducing the exposure time. However, for the purpose well control, the wellbore geometry and volumes differ from those obtained via a conventional drilling technique, thereby requiring a different approach. This study discusses well control principles for CwD operations. It presents a simplified method for evaluating the maximum kick tolerance and allowable well shut-in time for both conventional and CwD techniques using a mathematical model. Preliminary results revealed that the use of CwD leads to an annulus pressure loss three times higher than that observed in the conventional drilling. In addition, the kick tolerance is reduced by 50% and the maximum allowable well shut-in time is reduced by 65%, making an early kick detection system necessary. 相似文献
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Dense plexuses of neurones containing immunoreactive vasoactive intestinal peptide (VIP) have been found in discrete areas of the central nervous system and in peripheral organs, including the gastrointestinal tract, pancreas and urogenital system. In many of these locations VIP is concentrated in nerve endings, where it can be released by high K+ concentrations in a Ca2+-dependent manner. VIP release may also be provoked by electrical stimulation of nerves, for example the vagus. VIP thus shows some of the features of neurotransmitter or neuromodulator substances. The presence of immunoreactive VIP in the fine terminal varicosities as well as in the cell bodies of neurones suggests that it might be transported from the perikaryon, where it is presumably formed, to the nerve endings, through the axonal transport system. Such transport would be in keeping with a role for the peptide as a neurohumor or neurohormone. We report here that VIP accumulates in constricted rat sciatic nerves in a manner suggesting fast, anterograde axonal flow. 相似文献
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Cell penetrating peptides: overview and applications to the delivery of oligonucleotides 总被引:1,自引:1,他引:0
F. Said Hassane A. F. Saleh R. Abes M. J. Gait Bernard Lebleu 《Cellular and molecular life sciences : CMLS》2010,67(5):715-726
Crossing biological barriers represents a major limitation for clinical applications of biomolecules such as nucleic acids,
peptides or proteins. Cell penetrating peptides (CPP), also named protein transduction domains, comprise short and usually
basic amino acids-rich peptides originating from proteins able to cross biological barriers, such as the viral Tat protein,
or are rationally designed. They have emerged as a new class of non-viral vectors allowing the delivery of various biomolecules
across biological barriers from low molecular weight drugs to nanosized particles. Encouraging data with CPP-conjugated oligonucleotides
have been obtained both in vitro and in vivo in animal models of diseases such as Duchenne muscular dystrophy. Whether CPP-cargo
conjugates enter cells by direct translocation across the plasma membrane or by endocytosis remains controversial. In many
instances, however, endosomal escape appears as a major limitation of this new delivery strategy. 相似文献
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Kolliyil S. Mohamed K.K. Sajikumar Nadakkal Ragesh T.V. Ambrose J. Jayasankar K.P. Said Koya 《Journal of Natural History》2018,52(29-30):1869-1882
The distribution pattern of purpleback flying squid and the relationship between its abundance and environmental variables in the south-eastern Arabian Sea were analysed using a geographical information system (GIS) and a generalised additive model (GAM). Highest abundances were observed during December and January within 10 and 13°N and 71 and 72°E around the Lakshadweep Islands. The mean abundance in the area was 4.21 tonnes/km2 and the maximum sustainable yield (MSY) was estimated as 0.63 million tonnes. GAM indicated that very high squid abundance was associated with low values of dissolved oxygen (6.01–6.27 mg/L), sea surface temperature (28.03–28.62°C), pH (7.75–8.56), salinity (30.42–34.48 psu), chlorophyll-a (0.4–0.6 mg/m3), zooplankton biomass (0.23–0.64 mL/m3), and shallow 20°C isotherm (101.2–134.7 m) and mixed layer depth (17.8–29.8 m). As a carnivore from paralarval stages, S. oualaniensis depends on secondary and tertiary production to sustain its population for which primary production is used up. In the tropical Arabian Sea where temperature differences are not so pronounced, S. oualaniensis distribution was found to be related to a low but very narrow sea surface temperature (SST) band. There is sufficient fishable biomass in the area to possibly launch a new targeted oceanic squid fishery from the western seaboard of India. 相似文献
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Implement VLANs essentially creating smaller broadcast domains at layer 2, means that broadcasts sent out from a node in one VLAN won' t be forwarded to ports configured to belong to a different VLAN. In this paper, we assigning users to VLAN groups on a switch, this help to gain the flexibility to add only the users you want into that broadcast domain regardless of their physical location. This setup can also work to block broadcast storms caused by a faulty network interface card (NIC) as well as prevent an intermediate device from propagating broadcast storms throughout the entire internetwork. 相似文献
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Induction of somatic hypermutation in immunoglobulin genes is dependent on DNA polymerase iota 总被引:12,自引:0,他引:12
Somatic hypermutation of immunoglobulin genes is a unique, targeted, adaptive process. While B cells are engaged in germinal centres in T-dependent responses, single base substitutions are introduced in the expressed Vh/Vl genes to allow the selection of mutants with a higher affinity for the immunizing antigen. Almost every possible DNA transaction has been proposed to explain this process, but each of these models includes an error-prone DNA synthesis step that introduces the mutations. The Y family of DNA polymerases--pol eta, pol iota, pol kappa and rev1--are specialized for copying DNA lesions and have high rates of error when copying a normal DNA template. By performing gene inactivation in a Burkitt's lymphoma cell line inducible for hypermutation, we show here that somatic hypermutation is dependent on DNA polymerase iota. 相似文献
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