The quantitative determination and identification of bio-/chemical molecules at ultra-low concentrations is a hot topic in several fields including medical diagnostics, environmental science, and ...homeland security. Molecular detection techniques are conventionally based on optical, electrochemical, electronic, or gravimetric methodologies. Among these methods, surface-enhanced Raman spectroscopy (SERS) is considered as one of the most reliable, sensitive and selective techniques for non-destructive molecular analysis through the amplification of electromagnetic fields and/or creation of charge-transfer states between the chemisorbed analyte molecule and SERS active platform. Unfortunately, the applicability of SERS is rather limited, which is mainly due to the lack of highly sensitive SERS platforms with good stability and reproducibility. In line with this, metal nanoparticles (
e.g.
, Au, Ag, and Cu) have been extensively exploited as SERS active platforms. Although the utilization of metallic nanoparticles in SERS is simple and cost-effective, the poor controllability of the structures and limited formation of hot spots in the detection zone leads to discrepancy in the resulting SERS signals. For these reasons, in the past few years, researchers have focused on fabricating 3-dimensional (3D) SERS platforms, which increase the adsorption of analyte molecules and facilitate hot spot formation in all three dimensions. However, the fabrication of 3D SERS platforms is mostly expensive and technologically demanding. Therefore, the discovery of non-metal alternative approaches is of great interest not only to widen SERS applications but to further elucidate fundamental questions. Considering recent developments on the fabrication and application of SERS active platforms, this review is structured in 3 main directions; (1) implementation of the plasmonic nanoparticles having different shapes into SERS-active platforms, (2) highlighting recent developments in the fabrication and application of 3D SERS-active platforms, and (3) examination of recent novel inorganic and organic semiconductor based platforms for SERS applications. At the end, we conclude with the promises and challenges for the future evolution of SERS.
The recent focus on SERS-active materials has shifted from conventional plasmonic surfaces to alternative 3D structures and semiconductors.
Intense Cenozoic magmatism accompanied the convergence and collision of the Eurasian, African and Arabian plates. In the Cappadocia Region of Central Anatolia, widespread and abundant volcanism ...developed from the late Miocene to the Quaternary. Calc-alkaline pyroclastic products and lava erupted diffusely during the late Miocene and Pliocene. Both calc-alkaline and Na-alkaline volcanic rocks were emplaced in close spatial and temporal proximity during the Plio-Pleistocene. Here we focus on the Plio-Pleistocene monogenetic activity, which produced two types of rocks: calc-alkaline volcanic rocks ranging in composition from basalts to rhyolites and occurring around the Acıgöl caldera, the Göllü Dağ dome and the Hasan Dağ and Erciyes Dağ composite volcanoes; Na-alkaline volcanic rocks ranging from alkali basalts to mugearites and cropping out in monogenetic centres in Karapınar, along the WSW flank of Hasan Dağ, in Acıgöl and near the Kızılırmak River, northwest of Nevşehir.
The coeval occurrence of calc-alkaline and Na-alkaline volcanism observed here is in striking contrast with activity in the surrounding Western and Eastern Anatolia regions, where the calc-alkaline volcanic rocks are distinctly older than the Na-alkaline ones. The Sr and Nd isotopic compositions of the mantle sources of both rock types show a narrow, overlapping range of values (87Sr/86Sr~0.70395–0.70474 and 143Nd/144Nd~0.51268–0.51281 for the calc-alkaline products, 0.70334–0.70524 and 0.51268–0.51293 for the Na-alkaline ones). In addition, most of the Na-alkaline products, like the calc-alkaline rocks, show an arc-type distribution of incompatible trace elements, with marked enrichments in LILE (Large-Ion Lithophile Elements) and negative HFSE (High Field Strength Elements) anomalies. True intraplate magmas are absent in Cappadocia, where the genesis of Na-alkaline basalts is ascribed to mixing between different percentages of within-plate (OIB) and calc-alkaline magmas. Modelling reveals that the addition of 13% and 30% OIB-type melt to a calc-alkaline magma is enough to change a SiO2-oversaturated magma into an ol-hy-normative and ne-normative one, respectively, whereas the addition of 15% calc-alkaline magma to an OIB-type magma results in a negative NbTa anomaly in the primitive mantle-normalized spider diagrams.
The various types of products of recent volcanism in Cappadocia reflect the complex tectonic setting of the Central Anatolian Block: characterised by strike-slip tectonics and local extensional pull-apart basins, different magma types formed contemporaneously through decompression melting at different depths.
In this scenario, the calc-alkaline magmas derived from partial melting of a mantle wedge modified by a subduction component, whereas the within-plate (OIB) magmas derived from a deeper, unmodified sub-slab mantle source. Mixing between calc-alkaline and within-plate magmas during their rise to the surface produced the Na-alkaline Cappadocia basalts. The very low rate of extension allowed within-plate magmas (OIB) to reach the surface after having interacted with the overlying calc-alkaline magmas in the late stages of Cappadocia volcanism.
•Lower Pliocene to Pleistocene monogenetic volcanism in Cappadocia (Central Anatolia).•Coeval calc-alkaline and Na-alkaline activity.•Channelling of OIB-type magmas into the subcontinental mantle wedge.•Geodynamic evolution of the Anatolian block.
Natural products play an important part in synthetic chemistry since they have many pharmacological properties and are used as active drug compounds in pharmaceutical chemistry. However, synthesis of ...these complex molecules is difficult due to the requirement of various synthetic steps, which include highly regio- and stereoselectivity. Therefore, oxidative radical cyclization assisted by manganese(III) acetate serves as an important step in obtaining spiro-, tricyclic, tetracyclic, and polycyclic derivatives of these compounds. Manganese(III)-based reactions offer a single-step regio- and stereoselective cyclizations and α-acetoxidations, reducing the number of synthetic steps. Also, the manganese(III)-mediated oxidative free radical cyclization method has been successfully applied for the synthesis of cyclic structures found in many natural products. This article presents a broad overview of manganese(III)-based radical reactions of natural products as a key step in overall synthesis. The authors have classified natural product synthesis processes assisted by manganese(III) acetate as intermolecular, intramolecular, oxidation, acetoxidation, aromatization, and polymerization reactions, respectively.
In this study, we propose the synthesis of silver (Ag) nanoparticle decorated TiO2 nanoflowers (TNFs) using a polymeric conformal thin film of 3,4-dihydroxyphenyl-L-alanine (PLDOPA). The size, as ...well as interparticle distance of the decorated Ag nanostructures, were tuned by simply changing the number of supplied Ag ions. The resultant nanocomposite system (TNF@PLDOPA@Ag) showed unique SERS activity with high reproducibility and an enhancement factor of 4.2 × 107. Also, as an ideal photocatalytic system, the TNF@PLDOPA@Ag enabled the catalytic degradation of malachite green under visible light irradiation.
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•Silver nanostructure decorated TiO2 nanoflowers (TNFs) were fabricated using a thin film of the polymer of L-DOPA.•The PLDOPA layer enabled the reduction of silver ions and adsorption of the resultant silver nanostructures.•The size and interparticle distance of the deposited Ag nanostructures were manipulated via the number of supplied Ag ions.•The TNF@PLDOPA@Ag nanosystem showed unique SERS activity with high reproducibility and an enhancement factor of 4.2 ×107.•The TNF@PLDOPA@Ag system enabled the catalytic degradation of malachite green under visible light irradiation.
Upon excitation with an intense laser pulse, a symmetry-broken ground state can undergo a non-equilibrium phase transition through pathways different from those in thermal equilibrium. The mechanism ...underlying these photoinduced phase transitions has long been researched in the study of condensed matter systems1, but many details in this ultrafast, non-adiabatic regime still remain to be clarified. To this end, we investigate the light-induced melting of a unidirectional charge density wave (CDW) in LaTe3. Using a suite of time-resolved probes, we independently track the amplitude and phase dynamics of the CDW. We find that a fast (approximately 1 picosecond) recovery of the CDW amplitude is followed by a slower re-establishment of phase coherence. This longer timescale is dictated by the presence of topological defects: long-range order is inhibited and is only restored when the defects annihilate. Our results provide a framework for understanding other photoinduced phase transitions by identifying the generation of defects as a governing mechanism.
Fluorine doped ZnO thin films were grown by chemical spray pyrolysis technique of zinc acetate and ammonium fluoride, and the effect of fluorine content on structural, optical and electrical ...properties were evaluated. The structural, morphological, optical properties of ZnO films were investigated by XRD (X-ray diffraction), AFM (Atomic force microscopy), SEM (Scanning electron microscop) and UV–Vis spectroscopy, respectively. According to results, it was observed that all films had polycrystalline texture with hexagonal wurtzite crystal structure and film surface were made up of nano-scale grains, varied by fluorine content. Optical properties showed that optical band gap energy of ZnO changed from 3.28 to 3.24 eV with F content. Shrinkage effect was assessed as the cause in the variation of optical band gap values. Finally, current-voltage (I-V) analysis was performed in Au/ZnO:F/p-Si device in dark and light conditions and certain diode parameters such as ideality factor, barrier height and series resistance were calculated and discussed in detail.
Aims
To assess the tolerability of initiating/uptitrating sacubitril/valsartan (LCZ696) from 50 to 200 mg twice daily (target dose) over 3 and 6 weeks in heart failure (HF) patients (ejection ...fraction ≤35%).
Methods and results
A 5‐day open‐label run‐in (sacubitril/valsartan 50 mg twice daily) preceded an 11‐week, double‐blind, randomization period 100 mg twice daily for 2 weeks followed by 200 mg twice daily (‘condensed’ regimen) vs. 50 mg twice daily for 2 weeks, 100 mg twice daily for 3 weeks, followed by 200 mg twice daily (‘conservative’ regimen). Patients were stratified by pre‐study dose of angiotensin‐converting enzyme inhibitor/angiotensin‐receptor blocker (ACEI/ARB; low‐dose stratum included ACEI/ARB‐naïve patients). Of 540 patients entering run‐in, 498 (92%) were randomized and 429 (86.1% of randomized) completed the study. Pre‐defined tolerability criteria were hypotension, renal dysfunction and hyperkalaemia; and adjudicated angioedema, which occurred in (‘condensed’ vs. ‘conservative’) 9.7% vs. 8.4% (P = 0.570), 7.3% vs. 7.6% (P = 0.990), 7.7% vs. 4.4% (P = 0.114), and 0.0% vs. 0.8% of patients, respectively. Corresponding proportions for pre‐defined systolic blood pressure <95 mmHg, serum potassium >5.5 mmol/L, and serum creatinine >3.0 mg/dL were 8.9% vs. 5.2% (P = 0.102), 7.3% vs. 4.0% (P = 0.097), and 0.4% vs. 0%, respectively. In total, 378 (76%) patients achieved and maintained sacubitril/valsartan 200 mg twice daily without dose interruption/down‐titration over 12 weeks (77.8% vs. 84.3% for ‘condensed’ vs. ‘conservative’; P = 0.078). Rates by ACEI/ARB pre‐study dose stratification were 82.6% vs. 83.8% (P = 0.783) for high‐dose/‘condensed’ vs. high‐dose/‘conservative’ and 84.9% vs. 73.6% (P = 0.030) for low‐dose/‘conservative’ vs. low‐dose/‘condensed’.
Conclusions
Initiation/uptitration of sacubitril/valsartan from 50 to 200 mg twice daily over 3 or 6 weeks had a tolerability profile in line with other HF treatments. More gradual initiation/uptitration maximized attainment of target dose in the low‐dose ACEI/ARB group.
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•Compounds 2a and 2b were obtained in high yields under mild reaction conditions.•Radical addition of 2a and 2b to various alkenes using Mn(OAc)3 was achieved.•New classes of ...compounds (4a–i) were synthesized under microwave irradiation.
2-Hydroxy-4H-benzo4,5thiazolo3,2-apyrimidin-4-one 2a and 7-hydroxy-5H-thiazolo3,2-apyrimidin-5-one 2b, were obtained in high yields under mild conditions from the cyclization reactions of bis-(2,4,6-trichlorophenyl) malonate and 2-aminobenzothiazole or 2-aminothiazole, respectively. A new class of compounds, 2,3-dihydro-4H-benzo4,5thiazolo3,2-afuro2,3-dpyrimidin-4-ones and 6,7-dihydro-5H-furo2,3-dthiazolo3,2-apyrimidin-5-ones, were synthesized via the microwave assisted radical addition of compounds 2a and 2b to various alkenes using manganese(III) acetate. A preliminary acetylcholine esterase (AchE) inhibition test of compound 4e showed excellent (92%) inhibitory potential, comparable with the standard drug Donapezil®.
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