A dual-mode DNA sensor was constructed to detect nucleic acid sensitively and selectively. Based on dendritic porous silica nanoparticles (DPSNs) and hybridization chain reaction (HCR) amplification ...strategy, the fabricated DNA sensor showed good sensitivity with low detection limits down to 2.18 pM and 4.02 pM by fluorescence (excited at 488 nm and emitted at 508 nm) and personal glucose meter (PGM) assays, respectively. This dual-mode detection of DNA offered superior reliability and accuracy and could meet the requirements of different testing environments, including laboratory confirmation and portable detection. Moreover, the impact of nanoparticles morphology on detection performance was also discussed. Due to the center-radial pores, DPSNs had high curvature morphology, which improved the coverage capacity, footprint, and deflection angle of probes. This work fabricated a dual-mode DNA sensor and revealed the relationship between morphology and detection performance, which brought new insights in novel biosensor development.
Graphical abstract
Due to the high electrophilic nature of azo-dienophiles, azo-Diels–Alder proceeds rapidly even without the need of a catalyst and is therefore regarded as the “click reaction”. This spontaneity ...causes strong background reaction and poses a daunting challenge to chemists for developing the catalytic asymmetric version. Reported herein is the first catalytic asymmetric dearomative azo-Diels–Alder reaction between 2-vinylindoles and triazoledione. This protocol makes use of the high energy barrier of dearomatization to avert the strong background reaction of azo-Diels–Alder reaction, allowing the implementation of the projected reaction at ambient temperature. Density functional theory calculations have been performed to gain insights into the reaction mechanism and the origins of the enantioselectivity. By using this method, a variety of tetracyclic indole derivatives have been readily prepared in good to excellent yields and with excellent diastereo- and enantio‑selectivities (33 examples, up to 97% yield and >99% ee, >20:1 dr).
Reported herein is the first catalytic asymmetric dearomative azo-Diels–Alder reaction between 2-vinylindoles and triazoledione. This protocol makes use of the high energy barrier of dearomatization to avert the strong background reaction of azo-Diels–Alder reaction, allowing the implementation of the projected reaction at ambient temperature. Display omitted
A belt of khondalite-series rocks in the Western Block of the North China craton (NCC) are considered to represent products of the collision between the north Yinshan and the south Ordos terranes ...before final amalgamation of the NCC basement. The Jining Complex of Inner Mongolia occurs in the eastern part of the Khondalite Belt and is crosscut by the Trans-North China Orogen. Khondalite rocks of the Jining Complex mainly comprise sillimanite-garnet gneiss, garnet/sillimanite-bearing granite, massive porphyritic granite, garnet quartzite, calc-silicate, and marble with minor felsic gneiss and mafic granulite. LA-ICP-MS, U-Pb dating and cathodoluminescence (CL) image analysis of zircons from five rocks from the complex, i.e. Sil-Bt-Grt leptynite gneiss, Spl-Sil-Ksp-Grt vein in (Crd)-Sil-Grt gneiss, Sil-Grt-K-Fsp mylonite from a shear zone, Crd-bearing Sil-Grt gneiss, and granite were used to determine protolith and metamorphic ages of the khondalite-series rocks. Results of 315 detrital zircon grains indicate five age populations: 2410-2550 Ma, 2162 Ma, 2047-2099 Ma, 1950-1993 Ma, and 1866 Ma. CL investigation reveals that zircon grains of most samples are rounded, unzoned with low Th/U, indicating a metamorphic origin, whereas quite a few grains in some rocks are characterized by magmatic oscillatory zoning and comparatively high Th/U, and are typically overgrown by metamorphic, low CL rims with low Th/U. Three samples of Sil-Bt-Grt gneiss record oldest ages of ∼2550-2480 Ma, suggesting an Archaean/early Palaeoproterozoic provenance for the Jining Complex. Ages of ∼2162-2047 Ma are interpreted as the metamorphic modified inherited source of supercrustal protoliths of the khondalite-series rocks. The khondalite depositional age is defined as 2228-2027 Ma by concordant ages obtained in this research. The Sil-Ksp-Grt vein and the granite have single population ages of 1985 ± 28 Ma and 1957 ± 19 Ma, respectively, and are inferred to record the same metamorphic event, i.e. formation of the Khondalite Belt within the Western Block owing to the collision of the north Yinshan and the south Ordos terranes. The Sil-Grt-K-Fsp mylonite yields a single group age of 1866 ± 22 Ma, which may date final suturing of the Eastern Block and the Western Block and stabilization of the NCC.
Saturated cyclic amines (aza-cycles) are ubiquitous structural motifs found in pharmaceuticals, agrochemicals, and bioactive natural products. Given their importance, methods that directly ...functionalize aza-cycles are in high demand. Herein, we disclose a fundamentally different approach to functionalizing cyclic amines which relies on C–C cleavage and attendant cross-coupling. The initial functionalization step is the generation of underexplored N-fused bicyclo α-hydroxy-β-lactams under mild, visible light conditions using a Norrish–Yang process to affect α-functionalization of saturated cyclic amines. This approach is complementary to previous methods for the C–H functionalization of aza-cycles and provides unique access to various cross-coupling adducts. In the course of these studies, we have also uncovered an orthogonal, base-promoted opening of the N-fused bicyclo α-hydroxy-β-lactams. Computational studies have provided insight into the origin of the complementary C–C cleavage processes.
Abstract Background This study aimed to assess the public knowledge regarding Alzheimer’s Disease (AD) in Zhuhai, China, focusing on identifying knowledge gaps and the influence of demographic and ...health factors. Methods A cross-sectional study was conducted in Zhuhai, China, from October to November 2022. A total of 1986 residents from 18 communities were selected employing stratified multi-stage equi-proportional sampling. Questionnaires covering general information and the Alzheimer’s Disease Knowledge Scale (ADKS) were investigated face-to-face. Ordinal multiclass logistic regression was applied to assess the relationship between AD awareness and demographic and health characteristics. Results The average ADKS score was 18.5 (SD = 3.36) in Zhuhai. The lowest awareness rates were observed in the “Symptoms” and “Caregiving” subdomains of ADKS, with rates of 51.01% and 43.78%, respectively. The correct rates for the 30 ADKS questions ranged from 16.62 to 92.6%, showing a bimodal pattern with clusters around 80% and 20%. Women (OR = 1.203, 95% CI: 1.009–1.435), individuals aged 60 years or older (OR = 2.073, 95% CI: 1.467–2.932), those living in urban areas (OR = 1.361, 95% CI: 1.117–1.662), higher average monthly household income per capita (OR = 1.641, 95% CI: 1.297–2.082), and without any neurological or mental disorders (OR = 1.810, 95% CI: 1.323–2.478) were more likely to have higher levels of awareness about Alzheimer’s disease. Conclusions Adults in Zhuhai show a limited knowledge of AD, particularly in the ‘Symptoms’ and ‘Caregiving’ subdomains. Upcoming health campaigns must focus on bridging the knowledge gaps in different subdomains of AD, especially among subgroups with lower awareness, as identified in our study.
In this paper, we concern ourselves with the following Kirchhoff-type equations:
where
,
and
are positive constants and
has critical growth. We use variational methods to prove the existence of ...ground state solutions. In particular, we do not use the classical Ambrosetti–Rabinowitz condition. Some recent results are extended.
Wearable biosensors as a user-friendly measurement platform have become a rapidly growing field of interests due to their possibility in integrating traditional medical diagnostics and healthcare ...management into miniature lab-on-body analytic devices. This paper demonstrates a flexible and skin-mounted band that combines superhydrophobic-superhydrophilic microarrays with nanodendritic colorimetric biosensors toward in situ sweat sampling and analysis. Particularly, on the superwettable bands, the superhydrophobic background could confine microdroplets into superhydrophilic microwells. On-body investigations further reveal that the secreted sweat is repelled by the superhydrophobic silica coating and precisely collected and sampled onto the superhydrophilic micropatterns with negligible lateral spreading, which provides an independent “vessel” toward cellphone-based sweat biodetection (pH, chloride, glucose and calcium). Such wearable, superwettable band-based biosensors with improved interface controllability could significantly enhance epidemical sweat sampling in well-defined sites, holding a great promise for facile and noninvasive biofluids analysis.
This paper presents new LA-ICP-MS zircon U-Pb geochronology, whole-rock major and trace element geochemistry, and Sr-Nd isotopes systematically on porphyritic granitic and K-feldspar granitic ...intrusions from the Dananhu belt, eastern Tianshan orogenic belt (ETOB). Zircon U-Pb dating indicates that the porphyritic granitic and K-feldspar granitic plutons were formed at 357±3 and 311±3 Ma, respectively. The porphyritic granites show geochemical and isotopic characteristics (high SiO2, low MgO and Mg#, depleted Sr-Nd isotopic values (about 0.703 4 and 6.13, respectively), with Nb/Ta (13.3–14.7) and Zr/Hf (31.0–33.9) ratios) similar to those of the crustal-derived magmas. The above characteristics suggest they were probably originated from juvenile lower crustal materials. The K-feldspar granites also have high SiO2, low MgO and Mg
#
, depleted Sr-Nd isotopic values (0.703 3–0.704 6 and 4.41–5.67, respectively). But some trace elements contents vary widely, with variable Nb/Ta (12.7–22.7), Zr/Hf (21.3–36.1) and Nb/La (0.38–1.07) ratios, indicating that the K-feldspar granites were formed by partial melting of juvenile lower crustal materials with old crustal materials. Combined with previous data on Carboniferous granitoids in the Dananhu belt, we infer that all the Carboniferous granitic plutons in the Dananhu belt were most likely emplaced in an island arc environment (Dananhu arc). Subsequently, a tectonic transition from oceanic subduction to post-collisional extension probably occurred in the ETOB.
The Daheishan Horst in Jilin Province, NE China, is the key geological unit that links the Solonker-Xar Moron-Changchun and Changchun-Yanji sutures, which are generally interpreted to mark the zone ...of closure of the Paleo-Asian Ocean along the southeastern margin of the Central Asian Orogenic Belt (CAOB). Here we investigate a suite of volcanic rocks from Daheishan and the Doushantouzi syenogranite intrusion to gain insights into the Permian–Triassic tectonic evolution of the eastern segment of the Paleo-Asian Ocean. Zircon U-Pb data and zircon rare earth element (REE) patterns indicate that the igneous suite formed during the Late Permian (ca. 253–256Ma) and underwent late-stage alteration during Early Triassic tectono-thermal events. The presence of older magmatic zircon grains in this igneous suite suggest multiple pulses of magmatism during the Permian in this region. The Daheishan volcanic rocks predominantly consist of intermediate-felsic rocks, including andesite, rhyodacite and rhyolite with minor basaltic lava. Geochemically, the basaltic rocks belong to calc-alkaline series, whereas the intermediate-felsic rocks classify as calc-alkaline to high-K calc-alkaline series. The Doushantouzi syenogranites belong to peraluminous I-type granites, with the A/CNK ratio between 1.06 and 1.15. All these rocks have an arc-like affinity with enriched light rare earth elements (LREE) and large ion lithophile elements (LILE; e.g. Rb, Ba and U) and depleted high field strength elements (HFSE; e.g. Nb, Ta and Ti). The Daheishan intermediate-felsic rocks and Doushantouzi syenogranites have higher SiO2 contents but lower MgO contents and Mg# values and plot within the field of experimentally derived partial melts from metabasaltic rocks in MgO vs. SiO2 diagram. These geochemical features, together with the positive εNd(t) (+1.6 to +4.6) and εHf(t) (+1.53 to +7.41) values of zircon grains, indicate that the primary magma of these intermediate-felsic rocks likely originated from the partial melting of a juvenile metabasaltic lower crust. In contrast, the basaltic lavas were probably derived from the partial melting of a depleted mantle wedge that was metasomatized by fluids from a subducted slab, as suggested by their low initial 87Sr/86Sr ratios and depleted εNd(t) (+3.6 to +4.4) values. These data, in conjunction with regional geological investigations, suggest that formation of this Late Permian igneous suite was related to the northward subduction of the Paleo-Asian oceanic plate beneath the Songliao-Xilinhot block and that the eastern segment of the Paleo-Asian Ocean did not close before the Late Permian.
Display omitted
•A suite of Late Permian igneous rocks in the Daheishan Horst were reported in this paper.•A tectonic setting at an active continental margin was proposed.•A link to the northward subduction of the Paleo-Asian oceanic plate was found beneath the Songliao-Xilinhot Block.
The geological toolbox for the analysis of orogenic processes has seen substantial additions over the recent decades. Major advances have been made in the ability to simulate geological conditions ...and processes by computer modeling, we have a much improved knowledge of geochemical processes (trace elements and isotopes in particular), and, last but not least, the range and versatility of micro-analytical methods and instrumentation available to us has been expanded dramatically. The latter aspect has had a particular impact on metamorphic petrology as the conventional tools to determine pressure-temperature-time paths via rock and mineral analysis combined with isotope geochronology have generally gained in precision and accuracy through a much improved resolution. Geochronology has moved from whole-grain analysis to spot analyses on zoned single grains while analyzing trace elements and isotopes at the same time. It is therefore possible to recognize complex multi-stage orogenic events in single samples or single grains. Diffusion profiles in minerals provide us with time-scales of metamorphic and magmatic processes. Major and trace elements as well as isotope profiles of mineral grains give us insight into changing ambient conditions during mineral growth. This special issue focuses on pressure-temperature conditions and geochronology of metamorphic rocks, isotope studies of magmatic rocks, partial melting and metasomatic processes, all with a view at tectonic implications and orogeny. Much of the evidence has been gained from small-scale observation and analysis. Diligent field work and detailed microscopic examination remain indispensable, though, as demonstrated clearly by the “expansion” of the
P-T
space as applicable to crustal metamorphic processes towards extreme pressures and temperatures. As a consequence, much interest has thus focused on UHP and UHT rocks and the orogenic processes that generate them. There is petrological evidence for subduction to, and subsequent exhumation from, depths in excess of 250 km. While this impacts substantially on the large-scale geodynamic models of orogenic processes, the evidence is gathered primarily from small-scale petrological observation. The same applies in principle to UHT granulites. To generate temperatures in the 900 to 1 100 °C range within the sillimanite stability field in orogenic heat budget models remains a serious challenge, however. The large overlap of solid-state metamorphism, partial anatexis and magmatic crystallization in
P-T
space suggests close interrelationships, and the role and contribution of the diverse magmatic activities in forming orogenic belts, from the onset of subduction to late-orogenic delamination or slab-break-off is crucial for our understanding of geodynamics, with focus on geochemistry and geochronology. Aspects of metasomatism in the framework of orogeny are given some special consideration in this issue. The topics include the formation of sagvandite, pyrope quartzite (or whiteschist), jadeitite and rodingite. One of the key questions addressed is the source and the nature of the fluids that triggered the different types of metasomatic events. Finally, it is shown how small-scale methods contribute to a better understanding of the formation of deep-seated mantle xenoliths.
PDF
