7,821 research outputs found
Concave Silica Nanosphere with a Functionalized Open-Mouthed Cavity as Highly Active and Durable Catalytic Nanoreactor
No full textDespite increasingly intensive research into catalytic hollow nanoreactors, most of the work has focused on the enclosed cavity structure, and attempts to use the open-mouthed cavity have not been made so far, most likely due to the lack of methodologies for producing and functionalizing such a structure. This paper reports a synthetic strategy toward open-mouthed cavity-based nanoreactors, which renders the SiO2 nanosphere with a concave surface and also immobilizes catalytic nanocrystals (NCs) specifically inside the concave region. By putting the Janus silica-encapsulated manganese oxide (MnO) nanoparticle, with its highly off-centered core@shell structure, through the thermal hollow-conversion process, the edge-touching MnO nanoparticle was transformed into a hollow hemispherical manganese silicate layer with an opening to the outside, thus producing the bitten apple-like structure, conc-(Ni/HMS)@SiO2, with an open-mouthed cavity on the SiO2 nanosphere. The galvanic replacement reaction occurring on the manganese-silicate layer of the conc-(Ni/HMS)@SiO2 afforded the site-specific immobilization of catalytic Pt NCs on the preformed concave interior surface, signifying the possible postsynthetic functionalization of an open-mouthed cavity which could be adapted for the development of a nanoreactor system. The newly developed nanoreactor, Pt@conc-SiO2, carrying tiny catalytic Pt NCs inside the semiexposed and also semiprotected pocket-like space, exhibited an increased reaction rate and a more extended range of applicable substrates in catalyzing the reduction of nitroarene compounds, compared with the enclosed cavity-based analogue, while preserving the high immobilization stability of Pt nanocatalysts during the recycling process.1151sciescopu
A Compact Index for Cartesian Tree Matching
No full textCartesian tree matching is a recently introduced string matching problem in which two strings match if their corresponding Cartesian trees are the same. It is considered appropriate to find patterns regarding their shapes especially in numerical time series data. While many related problems have been addressed, developing a compact index has received relatively less attention. In this paper, we present a 3n+o(n)-bit index that can count the number of occurrences of a Cartesian tree pattern in (m) time where n and m are the text and pattern length. To the best of our knowledge, this work is the first (n)-bit compact data structure for indexing for this problem
Indexing Isodirectional Pointer Sequences
No full textMany sequential and temporal data have dependency relationships among their elements, which can be represented as a sequence of pointers. In this paper, we introduce a new string matching problem with a particular type of strings, which we call isodirectional pointer sequence, in which each entry has a pointer to another entry. The proposed problem is not only a formalization of real-world dependency matching problems, but also a generalization of variants of the string matching problem such as parameterized pattern matching and Cartesian tree matching. We present a 2nlgσ+2n+o(n)-bit index that preprocesses the text T[1:n] so as to count the number of occurrences of pattern P[1:m] in (mlgσ) where σ is the number of distinct lengths of pointers in T. Our index is also easily implementable in practice because it consists of wavelet trees and range maximum query index, which are widely used building blocks in many other compact data structures. By compressing the wavelet trees, the index can also be stored into 2nH^*₀(T)+2n+o(n) bits where H^*₀(T) is the 0-th order empirical entropy of the distribution of pointer lengths of T
Simple Order-Isomorphic Matching Index with Expected Compact Space
No full textIn this paper, we present a novel indexing method for the order-isomorphic pattern matching problem (also known as order-preserving pattern matching, or consecutive permutation matching), in which two equal-length strings are defined to match when X[i] < X[j] iff Y[i] < Y[j] for 0 ≤ i,j < |X|. We observe an interesting relation between the order-isomorphic matching and the insertion process of a binary search tree, based on which we propose a data structure which not only has a concise structure comprised of only two wavelet trees but also provides a surprisingly simple searching algorithm. In the average case analysis, the proposed method requires (R(T)) bits, and it is capable of answering a count query in (R(P)) time, and reporting an occurrence in (lg |T|) time, where T and P are the text and the pattern string, respectively; for a string X, R(X) is the total time taken for the construction of the binary search tree by successively inserting the keys X[|X|-1],⋯,X[0] at the root, and its expected value is (|X|lgσ) where σ is the alphabet size. Furthermore, the proposed method can be viewed as a generalization of some other methods including several heuristics and restricted versions described in previous studies in the literature
Older adults' perceptions of age-friendliness with an emphasis on community supports and health services in a city in South Korea
No full textPurpose: This study tries to comprehend older adults' perspectives of community supports and health services in a South Korean city and identify important sociodemographic and health characteristics that affect their perspectives. Methods: 166 older adults were involved in this cross-sectional study. Questions on background characteristics and community supports and health services criteria (categorized as service accessibility, offer of services, voluntary support, or emergency care planning) based upon the WHO's Age-Friendly Cities Guide were used. The data were analyzed using paired and independent t-tests, one-way ANOVA, and hierarchical multiple regression analyses. Results: emergency care planning was rated as the most important by the participants (mean age=76.24 years, 22.9% male), while its current level of performance was lowly appraised (p < .001). The rated importance for each category differed based on individual characteristics. Depression (p=.016), older age (p=.012), and restricted network type (p=.039) were significantly related to ascribing a higher degree of importance to community services. Conclusion: Community initiatives are warranted to optimize emergency care for older adults. This planning must be based on the unique characteristics of older adults in coordination with supportive resources. In addition, comprehensive assessments are warranted before implementing action plans to ensure that the multi-dimensional problems of older adults are incorporated.N
Spontaneous Pt Deposition on Defective Surfaces of In2O3 Nanocrystals Confined within Cavities of Hollow Silica Nanoshells: Pt Catalyst-Modified ITO Electrode with Enhanced ECL Performance
No full textAlthough the deposition of metallic domains on a preformed semiconductor nanocrystal provides an effective pathway to access diverse hybrid nanocrystals with synergistic In2O3 metal/semiconductor heterojunction interface, those reactions that take place on the surface of semiconductor nanoscrystals have not been investigated thoroughly, because of the impediments caused by the surface-capping organic surfactants. By exploiting the interfacial reactions occurring between the solution and nanoparticles confined with the cavities of hollow nanoparticles, we propose a novel nanospace-confined strategy for assessing the innate reactivity of surfaces of inorganic semiconductor nanoparticles. This strategy was adopted to investigate the newly discovered process of spontaneous Pt deposition on In2O3 nanocrystals. Through an in-depth examination involving varying key reaction parameters, the Pt deposition process was identified to be templated by the defective In2O3 surface via a unique redox process involving the oxygen vacancies in the In2O3 lattice, whose density can be controlled by high-temperature annealing. The product of the Pt-deposition reaction inside the hollow silica nanoparticle, bearing In2O3-supported Pt catalysts inside the cavity protected by a porous silica shell, was proved to be an effective nanoreactor system which selectively and sustainably catalyzed the reduction reaction of small-sized aromatic nitro-compounds. Moreover, the surfactant-free and electroless Pt deposition protocol, which was devised based on the surface chemistry of the In2O3 nanoparticles, was successfully employed to fabricate Pt-catalyst-modified ITO electrodes.with enhanced electrogenerated chemiluminescece (ECL) performance.111sciescopu
Leveraging network analysis to determine sex differences in factors associated with frailty among older adults living alone
No full textBACKGROUND: Frailty is a complex geriatric syndrome typically characterized by multiple underlying etiological factors. We determined the contributing factors, by sex, using a network analysis. METHODS: The study sample consisted of a cross-sectional cohort of community-dwelling older adults aged ≥ 65 years living alone in a Korean city (N = 1,037). Frailty was assessed via the Korean Frailty Index. Participants were assessed for sociodemographic, health-related, mental and cognitive, and social characteristics. Mixed graphical models including all variables were estimated using the R-package mgm discretely by sex. We also used the Walktrap cluster algorithm to identify differences in the network structure in terms of connectivity around frailty between the sex groups for further insights. RESULTS: In both the networks for males and females, frailty correlated most strongly with nutritional status, presence of complex chronic disease, and self-efficacy, and exhibited proximity to decreased sleep quality and loneliness. However, frailty showed an association with suicidal ideation and the number of falls per year only in males, whereas it showed an association with functional disabilities only in females. The overall network connectivity around frailty was stronger with dense interactions (more edges) in the network for females than for males. CONCLUSIONS: The results signify the need for sex-group customized multi-domain assessments and interventions for the prevention and improvement of frailty among community-dwelling older adults
Access to Enantioenriched Benzylic 1,1-Silylboronate Esters by Palladium-Catalyzed Enantiotopic-Group Selective Suzuki-Miyaura Coupling of (Diborylmethyl)silanes with Aryl Iodides
No full textThis work describes the palladium-catalyzed enantiotopic-group selective Suzuki-Miyaura cross-coupling of (diborylmethyl)silanes with aryl iodides. The combination of a Pd(TFA)(2) and rev-Josiphos-type ligand bearing a 3,5-bis(trifluoromethyl)phenyl as benzylic phosphine substituent in the presence of NaI as an additive and NaOMe as a base promotes the reaction to high efficiency and enantioselectivity. This method provides a convenient approach for synthesizing chiral benzylic 1,1-silylboronate esters from readily accessible reagents. Synthetic applications including stereospecific C-O, C-N, and C-C bond-forming reactions of boron group are also demonstrated.11sciescopu
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