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排序方式: 共有2040条查询结果,搜索用时 15 毫秒
51.
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Gernand W Solnica B Naskalski JW 《Clinica chimica acta; international journal of clinical chemistry》2007,384(1-2):160-162
BACKGROUND: Flexible fitting of quality control procedures to method performance is an inseparable element of a cost-effective quality management strategy. However, opinions on method performance, based on a restricted number of quality control results used to calculate bias and imprecision, can vary due to the random nature of the data-gathering process. METHODS: We present an example of the bootstrap technique application in evaluating method performance estimates. RESULTS: Our analysis reveals substantial variability in method performance assessment results that should not be omitted. We suggest that the best way of using information concerning method performance is to consider the information in a probabilistic manner. Method performance is a feature presented with an element of probability. The effectiveness of a quality control procedure should be assessed with regard to this probability. CONCLUSIONS: Presented example of a bootstrap technique application increases our awareness of the uncertainty that accompanies method performance judgment and quality control planning. 相似文献
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Tomasz Trzepieciski Andrzej Kubit Andrzej Dzierwa Bogdan Krasowski Wojciech Jurczak 《Materials》2021,14(7)
The article presents the results of the analysis of the interactions between the single point incremental forming (SPIF) process parameters and the main roughness parameters of stiffened ribs fabricated in Alclad aluminium alloy panels. EN AW-7075-T6 and EN AW-2024-T3 Alclad aluminium alloy sheets were used as the research material. Panels with longitudinal ribs were produced with different values of incremental vertical step size and tool rotational speed. Alclad is formed of high-purity aluminium surface layers metallurgically bonded to aluminium alloy core material. The quality of the surface roughness and unbroken Alclad are key problems in SPIF of Alclad sheets destined for aerospace applications. The interactions between the SPIF process parameters and the main roughness parameters of the stiffened ribs were determined. The influence of forming parameters on average roughness Sa and the 10-point peak–valley surface roughness Sz was determined using artificial neural networks. The greater the value of the incremental vertical step size, the more prominent the ridges found in the inner surface of stiffened ribs, especially in the case of both Alclad aluminium alloy sheets. The predictive models of ANNs for the Sa and the Sz were characterised by performance measures with R2 values lying between 0.657 and 0.979. A different character of change in surface roughness was found for sheets covered with and not covered with a soft layer of technically pure aluminium. In the case of Alclad sheets, increasing the value of the incremental vertical step size increases the value of the surface roughness parameters Sa and Sz. In the case of the sheets not covered by Alclad, reduction of the tool rotational speed increases the Sz parameter and decreases the Sa parameter. An obvious increase in the Sz parameter was observed with an increase in the incremental vertical step size. 相似文献
55.
Sajjad Mohsin I. Rayyif Hamzah Basil Mohammed Carmen Curuiu Alexandra Ctlina Bîrc Alexandru Mihai Grumezescu Bogdan tefan Vasile Lia Mara Diu Veronica Lazr Mariana Carmen Chifiriuc Grigore Mihescu Alina Maria Holban 《Materials》2021,14(11)
Zinc oxide (ZnO) nanoparticles (NPs) have been investigated for various skin therapies in recent years. These NPs can improve the healing and modulate inflammation in the wounds, but the mechanisms involved in such changes are yet to be known. In this study, we have designed a facile ZnO nano-coated dressing with improved antimicrobial efficiency against typical wound pathogens involved in biofilm and chronic infections. ZnO NPs were obtained by hydrothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy. Antibacterial and antibiofilm effects were evaluated against laboratory and clinical isolates of significant Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and Gram-positive (Staphylococcus aureus and Enterococcus faecalis) opportunistic pathogens, by quantitative methods. Our results have shown that the developed dressings have a high antibacterial efficiency after 6–24 h of contact when containing 0.6 and 0.9% ZnO NPs and this effect is similar against reference and clinical isolates. Moreover, biofilm development is significantly impaired for up to three days of contact, depending on the NPs load and microbial species. These results show that ZnO-coated dressings prevent biofilm development of main wound pathogens and represent efficient candidates for developing bioactive dressings to fight chronic wounds. 相似文献
56.
Maria Luisa Grilli Daniele Valerini Anca Elena Slobozeanu Bogdan O. Postolnyi Sebastian Balos Antonella Rizzo Radu Robert Piticescu 《Materials》2021,14(7)
Several applications, where extreme conditions occur, require the use of alloys often containing many critical elements. Due to the ever increasing prices of critical raw materials (CRMs) linked to their high supply risk, and because of their fundamental and large utilization in high tech products and applications, it is extremely important to find viable solutions to save CRMs usage. Apart from increasing processes’ efficiency, substitution, and recycling, one of the alternatives to preserve an alloy and increase its operating lifetime, thus saving the CRMs needed for its manufacturing, is to protect it by a suitable coating or a surface treatment. This review presents the most recent trends in coatings for application in high temperature alloys for aerospace engines. CRMs’ current and future saving scenarios in the alloys and coatings for the aerospace engine are also discussed. The overarching aim of this paper is to raise awareness on the CRMs issue related to the alloys and coating for aerospace, suggesting some mitigation measures without having the ambition nor to give a complete overview of the topic nor a turnkey solution. 相似文献
57.
Stringer-stiffened panels made of aluminium alloys are often used as structural elements in the aircraft industry. The load-carrying capacity of this type of structure cannot relieve the reduction in strength in the event of local buckling. In this paper, a method of fabrication of rib-stiffened panels made of EN AW-2024-T3 Alclad and EN AW-7075-T6 Alclad has been proposed using single point incremental forming. Panels made of sheets of different thickness and with different values of forming parameters were tested under the axial compression test. A digital image correlation (DIC)-based system was used to find the distribution of strain in the panels. The results of the axial compression tests revealed that the panels had two distinct buckling modes: (i) The panels buckled halfway up the panel height towards the rib, without any appreciable loss of rib stability, and (ii) the rib first lost stability at half its height with associated breakage, and then the panel was deflected in the opposite direction to the position of the rib. Different buckling modes can be associated with the character of transverse and longitudinal springback of panels resulting from local interaction of the rotating tool on the surface of the formed ribs. 相似文献
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David J. Loane Bogdan A. Stoica Flaubert Tchantchou Alok Kumar James P. Barrett Titilola Akintola Fengtian Xue P. Jeffrey Conn Alan I. Faden 《NeuroRx》2014,11(4):857-869
Traumatic brain injury (TBI) causes microglial activation and related neurotoxicity that contributes to chronic neurodegeneration and loss of neurological function. Selective activation of metabotropic glutamate receptor 5 (mGluR5) by the orthosteric agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG), is neuroprotective in experimental models of TBI, and has potent anti-inflammatory effects in vitro. However, the therapeutic potential of CHPG is limited due to its relatively weak potency and brain permeability. Highly potent, selective and brain penetrant mGluR5 positive allosteric modulators (PAMs) have been developed and show promise as therapeutic agents. We evaluated the therapeutic potential of a novel mGluR5 PAM, VU0360172, after controlled cortical impact (CCI) in mice. Vehicle, VU0360172, or VU0360172 plus mGluR5 antagonist (MTEP), were administered systemically to CCI mice at 3 h post-injury; lesion volume, hippocampal neurodegeneration, microglial activation, and functional recovery were assessed through 28 days post-injury. Anti-inflammatory effects of VU0360172 were also examined in vitro using BV2 and primary microglia. VU0360172 treatment significantly reduced the lesion, attenuated hippocampal neurodegeneration, and improved motor function recovery after CCI. Effects were mediated by mGluR5 as co-administration of MTEP blocked the protective effects of VU0360172. VU0360172 significantly reduced CD68 and NOX2 expression in activated microglia in the cortex at 28 days post-injury, and also suppressed pro-inflammatory signaling pathways in BV2 and primary microglia. In addition, VU0360172 treatment shifted the balance between M1/M2 microglial activation states towards an M2 pro-repair phenotype. This study demonstrates that VU0360172 confers neuroprotection after experimental TBI, and suggests that mGluR5 PAMs may be promising therapeutic agents for head injury.
Electronic supplementary material
The online version of this article (doi:10.1007/s13311-014-0298-6) contains supplementary material, which is available to authorized users. 相似文献60.
Dan J. Stein Sergio Aguilar-Gaxiola Jordi Alonso Ronny Bruffaerts Peter de Jonge Zharoui Liu Jose Miguel Caldas-de-Almeida Siobhan O’Neill Maria Carmen Viana Ali Obaid Al-Hamzawi Mattias C. Angermeyer Corina Benjet Ron de Graaf Finola Ferry Viviane Kovess-Masfety Daphna Levinson Giovanni de Girolamo Silvia Florescu Chiyi Hu Norito Kawakami Josep Maria Haro Marina Piazza Jose Posada-Villa Bogdan J. Wojtyniak Miguel Xavier Carmen C.W. Lim Ronald C. Kessler Kate M. Scott 《General hospital psychiatry》2014