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151.
Let Π = B_1/B_2/… /B_k be any set partition of[n]= {1,2,...,n} satisfying that entries are increasing in each block and blocks are arranged in increasing order of their first entries.Then Callan defined the flattened Π to be the permutation of[n]obtained by erasing the divers between its blocks,and Callan also enumerated the number of set partitions of[n]whose flattening avoids a single3-letter pattern.Mansour posed the question of counting set partitions of[n]whose flattening avoids a pattern of length 4.In this paper,we present the number of set partitions of[n]whose flattening avoids one of the patterns:1234,1243,1324,1342,1423,1432,3142 and 4132. 相似文献
152.
Andrew D. Turner Robert G. Hatfield Andy L. Powell Wendy Higman 《Analytical and bioanalytical chemistry》2010,397(2):743-749
Bivalve shellfish samples containing paralytic shellfish poisoning toxins were subjected to gamma irradiation dosage trials
in order to assess the potential suitability of the technique in the production of toxin reference materials. Two candidate
reference materials of tissue homogenates, mussels (Mytilus sp.) and native oysters (Ostrea edulis), were prepared in-house. Both were subjected to gamma irradiation at four different dose levels, 3.0, 6.0, 13.0 and 18.1 kGy.
Bacterial levels were shown to be eliminated in the mussels and significantly reduced in the oysters following irradiation
at all four dose levels. Paralytic shellfish poisoning (PSP) toxin concentrations were not significantly reduced in any of
the samples indicating the treatment had no adverse affect on the initial stability of any of the PSP toxins monitored. Chromatographic
results showed near-identical profiles for treated and non-treated samples inferring that no fluorescent toxin degradation
products or matrix interferences were produced during the irradiation process. Results therefore proved that gamma irradiation
treatment reduced bacterial levels within paralytic shellfish poisoning reference materials without compromising analyte content,
with the subsequent potential to enhance the stability of future candidate reference materials treated in this manner. 相似文献
153.
Chyun-Chau Fuh 《Communications in Nonlinear Science & Numerical Simulation》2009,14(8):3424-3431
Chaos is undesirable in many engineering applications since it causes a serious degradation of the system performance and restricts the system’s operating range. Therefore, the problem of controlling chaos has attracted intense interest in recent years. This paper proposes an approach for optimizing the control of chaotic systems with input saturation using an input-state linearization scheme. In the proposed approach, the optimal system gains are identified using the Nelder–Mead simplex algorithm. This algorithm does not require the derivatives of the cost function (or the performance index) to be optimized, and is therefore particularly applicable to problems with undifferentiable elements or discontinuities. Two numerical simulations are performed to demonstrate the feasibility and effectiveness of the proposed method. 相似文献
154.
155.
A bimetallic Ni-Al (2.5087(15) A) complex with an agostic alpha-C-H, [eta-C5H4CH=N(C6F5)]Fe[eta-C5H4PPh2]Ni(AlMe3), has been isolated and crystallographically established. The complex is active towards ethylene oligomerization/polymerization under moderate conditions. 相似文献
156.
Beale AM van der Eerden AM Grandjean D Petukhov AV Smith AD Weckhuysen BM 《Chemical communications (Cambridge, England)》2006,(42):4410-4412
An in situ cell, which is capable of obtaining time resolved soft X-ray data (200 eV < E < 3000 eV) under hydrothermal conditions has been developed and used to study the self-assembly processes occurring during microporous aluminophosphate crystallization. 相似文献
157.
Cooke G Garety JF Jordan B Kryvokhyzha N Parkin A Rabani G Rotello VM 《Organic letters》2006,8(11):2297-2300
[reaction: see text] We report the synthesis of flavin-stoppered hydrogen bonded [2]rotaxanes 1 and 2. We also report the electrochemically controllable properties of these systems in solution, and for derivative 2, as an electropolymerized thin film. 相似文献
158.
A one-pot ethylnylation and catalytic desilylation reaction was developed for the synthesis of mestranol and levonorgestrel. Addition of trimethylsilylacetylide to the carbonyl group at C-17 of the steroids yielded the C-17α-trimethylsilylacetylenyl adducts, which were desilylated with a catalytic amount of TBAF (0.050 equiv) in one pot to provide the corresponding mestranol and levonorgestrel both in 90% yields. A plausible mechanism was proposed for the catalytic desilylation through the regeneration of the fluoride ion from the reaction of alkoxide on the steroid with Me3SiF. The one-pot ethynylation and catalytic desilylation methodology provided an alternative route and avoided the traditional use of flammable and explosive acetylene gas toward the synthesis of mestranol and levonorgestrel. 相似文献
159.
2-Methoxyphenol (guaiacol) and its derivatives are potential marker compounds for wood smoke emissions in the atmosphere. To investigate the atmospheric reactivity of this type of compounds, rate coefficients for their reactions with hydroxyl (OH) radicals have been determined at 294 ± 2 K and 1 atm using the relative rate method with gas chromatography for chemical analysis. The rate coefficients (in units of cm3 molecule?1 s?1) are: 2-methoxyphenol, (7.53 ± 0.41) × 10?11; 3-methoxyphenol, (9.80 ± 0.46) × 10?11; 4-methoxyphenol, (9.50 ± 0.55) × 10?11; 2-methoxy-4-methylphenol, (9.45 ± 0.59) × 10?11; and methoxybenzene, (2.20 ± 0.15) × 10?11. The estimated atmospheric lifetime for 2-methoxyphenol is ~2 h, indicating that it is too reactive to be used as a tracer for wood smoke emissions. The reactivity of the methoxyphenols is compared with other substituted aromatics and interpreted in relation to the type, number, and positions of the different substituents on the aromatic ring. The atmospheric implications of the reactions are also discussed. 相似文献
160.
Prof. Dr. Ying Zhang Der-Shyang Kao Dr. Bing Gu Dr. Rajdeep Bomjan Dr. Mayank Srivastava Prof. Dr. Haojie Lu Prof. Dr. Daoguo Zhou Prof. Dr. W. Andy Tao 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(6):2255-2260
Studying the dynamic interaction between host cells and pathogen is vital but remains technically challenging. We describe herein a time-resolved chemical proteomics strategy enabling host and pathogen temporal interaction profiling (HAPTIP) for tracking the entry of a pathogen into the host cell. A novel multifunctional chemical proteomics probe was introduced to label living bacteria followed by in vivo crosslinking of bacteria proteins to their interacting host-cell proteins at different time points initiated by UV for label-free quantitative proteomics analysis. We observed over 400 specific interacting proteins crosslinked with the probe during the formation of Salmonella-containing vacuole (SCV). This novel chemical proteomics approach provides a temporal interaction profile of host and pathogen in high throughput and would facilitate better understanding of the infection process at the molecular level. 相似文献