Knowledge Mapping of Intracranial Aneurysm Clipping: A Bibliometric and Visualized Study (2001-2021).

BACKGROUND: Intracranial aneurysms (IAs) are common cerebrovascular diseases with high rates of mortality and disability. With the development of endovascular treatment technologies, the treatment of IAs has gradually turned to endovascular methods. However, because of the complex disease characteristics and technical challenges of IA treatment, surgical clipping still plays an important role. However, no summary has been performed of the research status and future trends in IA clipping. METHODS: Publications related to IA clipping from 2001 to 2021 were retrieved from the Web of Science Core Collection database. We conducted a bibliometric analysis and visualization study with the help of VOSviewer software and R program. RESULTS: We included 4104 articles from 90 countries. The volume of publications on IA clipping, in general, has increased. The United States, Japan, and China were the countries with the most contributions. The University of California, San Francisco, Mayo Clinic, and the Barrow Neurological Institute are the main research institutions. World Neurosurgery and the Journal of Neurosurgery were the most popular journal and most co-cited journal, respectively. These publications came from 12,506 authors, of whom Lawton, Spetzler, and Hernesniemi had reported the most studies. The reports from the past 21 years on IA clipping can generally be divided into 5 parts: (1) characteristics and technical difficulties of IA clipping; (2) perioperative management and imaging evaluation of IA clipping; (3) risk factors for subarachnoid hemorrhage caused by rupture after IA clipping; (4) outcomes, prognosis, and related clinical trials of IA clipping; and (5) endovascular management for IA clipping. "Occlusion," "experience," "internal carotid artery," "intracranial aneurysms," "management," and "subarachnoid hemorrhage" were the major keywords for future research hotspots. CONCLUSIONS: The results from our bibliometric study have clarified the global research status of IA clipping between 2001 and 2021. The United States contributed the most publications and citations, and World Neurosurgery and Journal of Neurosurgery can be considered landmark journals in this field. Studies regarding occlusion, experience, management, and subarachnoid hemorrhage will be the research hotspots related to IA clipping in the future.

Direct Detection of Reactive Gallium-Hydride Species on the Ga2O3 Surface via Solid-State NMR Spectroscopy.

Surface metal hydrides (M-H) are ubiquitous in heterogeneous catalytic reactions, while the detailed characterizations are frequently hindered by their high reactivity/low concentration, and the complicated surface structures of the host solids, especially in terms of practical solid catalysts. Herein, combining instant quenching capture and advanced solid-state NMR methodology, we report the first direct and unambiguous NMR evidence on the highly reactive surface gallium hydrides (Ga-H) over a practical Ga2O3 catalyst during direct H2 activation. The spectroscopic effects of 69Ga and 71Ga isotopes on the 1H NMR signal are clearly differentiated and clarified, allowing a concrete discrimination of the Ga-H signal from the hydroxyl crowd. Accompanied with quantitative and two-dimensional NMR spectroscopical methods, as well as density functional theory calculations, information on the site specification, structural configuration, and formation mechanism of the Ga-H species has been revealed, along with the H2 dissociation mechanism. More importantly, the successful spectroscopic identification and isolation of the surface Ga-H allow us to clearly reveal the critical but ubiquitous intermediate role of this species in catalytic reactions, such as propane dehydrogenation and CO2 hydrogenation reactions. The analytic approach presented in this work can be extended to other M-H analysis, and the insights will benefit the design of more efficient Ga-based catalysts.

Nature of Five-Coordinated Al in γ-Al2O3 Revealed by Ultra-High-Field Solid-State NMR.

Five-coordinated Als (Al(V)) on the surface of aluminas play important roles when they are used as catalysts or catalyst supports. However, the comprehensive characterization and understanding of the intrinsic structural properties of the Al(V) remain a challenge, due to the very small amount in commonly used aluminas. Herein, the surface structures of γ-Al2O3 and Al(V)-rich Al2O3 nanosheets (Al2O3-NS) have been investigated and compared in detail by multinuclear high-field solid-state NMR. Thanks to the high resolution and sensitivity of ultra-high-field (up to 35.2 T) NMR, the arrangements of surface Als were clearly demonstrated, which are substantially different from the bulk phase in γ-Al2O3 due to the structure reconstruction. It reveals for the first time that most of the commonly observed Al(V)s tend to exist as aggregated states on the surface of γ-Al2O3, like those in amorphous Al2O3-NS liable to structure reconstruction. Our new insights into surface Al(V) species may help in understanding the structure-function relationship of alumina.

Unraveling the Surface Hydroxyl Network on In2O3 Nanoparticles with High-Field Ultrafast Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy.

Hydroxyl groups are among the major active surface sites over metal oxides. However, their spectroscopic characterizations have been challenging due to limited resolutions, especially on hydroxyl-rich surfaces where strong hydroxyl networks are present. Here, using nanostructured In2O3 as an example, we show significantly enhanced discrimination of the surface hydroxyl groups, owing to the high-resolution 1H NMR spectra performed at a high magnetic field (18.8 T) and a fast magic angle spinning (MAS) of up to 60 kHz. A total of nine kinds of hydroxyl groups were distinguished and their assignments (µ1, µ2, and µ3) were further identified with the assistance of 17O NMR. The spatial distribution of these hydroxyl groups was further explored via two-dimensional (2D) 1H-1H homonuclear correlation experiments with which the complex surface hydroxyl network was unraveled at the atomic level. Moreover, the quantitative analysis of these hydroxyl groups with such high resolution enables further investigations into the physicochemical property and catalytic performance characterizations (in CO2 reduction) of these hydroxyl groups. This work provides insightful understanding on the surface structure/property of the In2O3 nanoparticles and, importantly, may prompt general applications of high-field ultrafast MAS NMR techniques in the study of hydroxyl-rich surfaces on other metal oxide materials.

89Y chemical shift anisotropy: a sensitive structural probe of layered yttrium hydroxides revealed by solid-state NMR spectroscopy and DFT calculations.

Anion-exchangeable Y2(OH)5X·nH2O (LYH-X, X = monovalent anions, n ≈ 1.5) materials are an ideal platform for incorporating the unique properties of layered metal hydroxides and rare-earth (RE) ions, and thus have exhibited promising prospects for various applications. To further improve the performance of LYH-X and related functional materials, their structure-property relationships must be explored. However, due to the intrinsic felxibility, extracting the local structural details of these materials is particularly challenging. In this work, we utilized a combined approach of 89Y solid-state NMR (ssNMR) spectroscopy and density functional theory (DFT) calculations to reveal the response of 89Y chemical shift anisotropy (CSA) in LYH-X to the structural changes including a small displacement of cationic yttrium hydroxide layers and intercalated anions. Such subtle structural changes are often associated with dehydration/rehydration, anion-exchange, exfoliation, and the self-assembly process of LYH-X and related functional materials, which are exceedingly difficult to detect using other techniques. The principal components of 89Y CSA show a larger variation range than isotropic chemical shifts, making CSA a more sensitive probe. In addition, it is found that the response of 89Y CSA to structural changes is distinct for Y sites with different local coordination environments, opening great opportunities to analyze each Y site within these materials. All these observations suggest that the strategy involving both experimental (89Y ssNMR) and theoretical (DFT) approaches can be utilized to extract previously unavailable ultrafine structural information of LYH-X and related materials, and provide fruitful insights into their thorough structure-property relationships.

Enhanced Fluoride Uptake by Layered Double Hydroxides under Alkaline Conditions: Solid-State NMR Evidence of the Role of Surface >MgOH Sites.

Layered double hydroxides (LDHs) are potential low-cost filter materials for use in fluoride removal from drinking water, but molecular-scale defluoridation mechanisms are lacking. In this research, we employed 19F solid-state NMR spectroscopy to identify fluoride sorption products on 2:1 MgAl LDH and to reveal the relationship between fluoride sorption and the LDH structure. A set of six 19F NMR peaks centered at -140, -148, -156, -163, -176, and -183 ppm was resolved. Combining quantum chemical calculations based on density function theory (DFT) and 19F{27Al} transfer of populations in double resonance (TRAPDOR) analysis, we could assign the peaks at -140, -148, -156, and -163 ppm to Al-F (F coordinated to surface Al) and those at -176 and -183 ppm to Mg-F (F coordinated to surface Mg only). Interestingly, the spectroscopic data reveal that the formation of Al-F is the predominant mode of F- sorption at low pH, whereas the formation of Mg-F is predominant at high pH (or a higher Mg/Al ratio). This finding supports the fact that the F- uptake of 2:1 MgAl LDH was nearly six times that of activated alumina at pH 9. Overall, we explicitly revealed the different roles of the surface >MgOH and >AlOH sites of LDHs in defluoridation, which explained why the use of classic activated alumina for defluoridation is limited at high pH. The findings from this research may also provide new insights into material screening for potential filters for F- removal under alkaline conditions.

The Role of Organic and Inorganic Structure-Directing Agents in Selective Al Substitution of Zeolite.

Organic and inorganic structure-directing agents (SDAs) impact Al distributions in zeolite, but the insights into how SDAs manipulate Al distribution have not been elucidated yet. Herein, the roles of different SDAs such as cyclohexylamine (CHA), hexamethylenimine (HMI), and Na+ in selective Al substitution of MCM-49 zeolite are investigated comprehensively by multinuclear solid-state NMR. The results demonstrate that MCM-49 synthesized with HMI shows relatively more T6 and T7 Al, while more T2 Al is observed using CHA. The formation of T2 Al in both MCM-49(HMI) and MCM-49(CHA) is derived from Na+, while protonated HMIs show bias in incorporation of T6 and T7 Al. Most HMIs are occluded in protonated status, and about half of CHAs are occluded in nonprotonated status. The close spatial proximity between nonprotonated CHAs and Na+ synergistically promotes the formation of zeolite structure, leading to more Na+ ions occluded in the zeolite channel with preferential T2 Al substitution.

Acidity and Local Confinement Effect in Mordenite Probed by Solid-State NMR Spectroscopy.

Herein, utilizing acetonitrile as the probe molecule, the acidity and host-guest interactions of H-mordenite (H-MOR) zeolites are investigated comprehensively by solid-state NMR spectroscopy and theoretical calculation. The locations and local configurations of Brønsted acid sites (BASs) in H-MOR are revealed by multinuclear and multidimensional NMR experiments with adsorption/coadsorption of acetonitrile (CD3CN) and trimethylphosphine (TMP). Moreover, the confinement effect of dual pores in MOR has been characterized via the quantitative determination of host-guest interactions between CH3CN and BASs. The 1H-15N dipolar measurement results and DFT calculations demonstrate that there are two kinds of acetonitrile molecules adsorbed in 12-membered ring (12MR) main channels with distinct mobility, where acetonitrile undergoes either partially restricted or highly flexible motion in the time scale of nanoseconds to microseconds. These two types of acetonitrile can exchange with temperature rising. In contrast, the mobility of acetonitrile in 8-membered ring (8MR) channels is very restricted due to the confinement of the framework.

[Treatment of vomiting in children patients with solid tumor by hewei zhiou recipe combined ondansetron hydrochloride].

OBJECTIVE: To observe the therapeutic efficacy of Hewei Zhiou Recipe (HZR) combined ondansetron hydrochloride (OH) in treating vomiting in children patients with solid tumor. METHODS: Eighty children patients with solid tumor at the Department of Tumor, Beijing Children's Hospital from January 2007 to January 2010 were randomly assigned to the treatment group and the control group by the random digit table method, 40 in each group. OH 4 mg was intravenously dripped to patients in the control group. Those in the treatment group took HZR on the basis of the same treatment as for the control group. The vomiting score and degree of the two groups were collected and compared by the end of the 1st to the 6th therapeutic course. RESULTS: There was no statistical difference in the vomiting degree between the two groups by the end of the 1st therapeutic course (Z = -0.470, P>0.05). The vomiting degree was lessened in the treatment group by the end of the 2nd to the 6th therapeutic course, showing statistical difference when compared with the control group (Z = - 2.966, -3.256, -3.453, -4.870, -3.627, respectively, P<0.01). CONCLUSION: HZR combined OH could effectively relieve the vomiting of children patients with solid tumor during chemotherapy.

[Study on nutrient and salinity in soil covered with different vegetations in Shuangtaizi estuarine wetlands].

Nutrient elements and salinity in soil covered by different vegetations including Phragmites australis (Clay.) Trin., Typha orientalis Presl., Puccinellia distans Parl, and Suaeda salsa in Shuangtaizi estuarine wetlands were investigated to study their distribution characteristics and to reveal the nutrient element variation during the vegetation succession processes. Results indicated that total potassium, total phosphorus and salinity were different significantly in soil between different plant communities while available phosphorus, total nitrogen, available nitrogen, available potassium, total sulfur, iron and soil organic carbon were different insignificantly. Correlation analysis suggested that soil organic carbon were related significantly to total nitrogen, available phosphorus, available potassium, which implied that decomposition of plant litter might be the mail source of soil nitrogen and available nutrient. Salinity was significantly related to total phosphorus and iron in soil. In Shuangtaizi estuarine wetland soil, ratios of carbon to nitrogen (R(C/N)) was in the range of 12.21-26.33 and the average value was 18.21, which was higher than 12.0. It indicated that soil organic carbon in Shuangtaizi estuarine mainly came from land but not ocean and plants contributed the most of soil organic matters. There was no significant difference in R(C/N) between soil from the four plant communities (F = 1.890, p = 0.151). R(C/N) was related significantly to sol salinity (r = 0.346 3, p = 0.035 8) and was increasing with soil salinity.

[Applying analytical hierarchy process to assess eco-environment quality of Heilongjiang province].

The analytical hierarchy process (AHP) was adopted to study the index system of eco-province and the index system was set up for eco-province construction. The comparison matrix was constructed on the basis of experts' investigation questionnaires. MATLAB 6.5 was used to confirm the weights of the indices. The general environment quality index model was used to grade the environment quality and assessed the progress of constructing eco-province in Heilongjiang province. The results indicate that it is feasible to apply the AHP to assess quantitatively the ecological environmental quality province-wide. The ecological environment quality of Heilongjiang province has been improved obviously from the beginning of eco-province construction.