Simple Cascade Research Articles

The Evolution Process between the Earthquake Swarm Beneath the Noto Peninsula, Central Japan and the 2024 M 7.6 Noto Hanto Earthquake Sequence

Several physical mechanisms of earthquake nucleation, such as pre-slip, cascade triggering, aseismic slip, and fluid-driven models, have been proposed. However, it is still not clear which model plays the most important role in driving foreshocks and mainshock nucleation for given cases. In this study, we focus on the relationship between an intensive earthquake swarm that started beneath the Noto Peninsula in Central Japan since November 2020 and the nucleation of the 2024 M7.6 Noto Hanto earthquake. We relocate earthquakes listed in the standard Japan Meteorological Agency (JMA) catalog since 2018 with the double-different relocation method. Relocated seismicity revealed that the 2024 M7.6 mainshock likely ruptured a thrust fault above a parallel fault where the M6.5 Suzu earthquake occurred in May 2023. We find possible along-strike and along-dip expansion of seismicity in the first few months at the beginning of the swarm sequence, while no obvious migration pattern in the last few days before the M7.6 mainshock was observed. Several smaller events occurred in between the M5.5 and M4.6 foreshocks that occurred about 4 and 2 minutes before the M7.6 mainshock. The Coulomb stress changes from the M5.5 foreshock were negative at the hypocenter of the M7.6 mainshock, which is inconsistent with a simple cascade triggering model. Moreover, an M5.9 foreshock was identified in the JMA catalog 14 s before the mainshock. Results from back-projection of high-frequency teleseismic P waves show a prolonged initial rupture process near the mainshock hypocenter lasting for ∼25 seconds, before propagating bi-laterally outward. Our results suggest a complex evolution process linking the earthquake swarm to nucleation of the M7.6 mainshock at a region of complex structures associated with the bend of a mapped large-scale reverse fault. A combination of fluid migration, aseismic slip and elastic stress triggering likely work in concert to drive both the prolonged earthquake swarm and the nucleation of the M7.6 mainshock.

Hydrothermal extraction of ulvans from Ulva spp. in a biorefinery approach

A simple cascade process based on the hydrothermal fractionation of Ulva spp. biomass was proposed. Considering the overall extraction yields (50 %), ulvan recovery (23 %), and ulvan composition, structural, mechanical and cytotoxic properties, the selected optimal final heating temperature was 160 °C. Ethanol precipitation provided the highest ulvan recovery yields but choline chloride precipitated ulvans showed stronger mechanical properties, G´ moduli 1.5·104 Pa and 3·104 Pa for ethanol and for choline chloride, respectively. Both products were safe on NCTC 929 mouse fibroblasts and after a cooling stage, formed films without requiring any additives. From the ulvan-free liquid fraction, one product with 43 % (wt, d.b.) phenolics and moderate antiradical properties and a byproduct containing nutrients and minerals were separated. The methane potential of the corresponding residual solids was influenced by the hydrothermal heating temperature and was doubled compared to than for the untreated seaweed biomass (60 mL/g VS). This scheme could be also applied to the wet algal biomass, in a chemical free alternative to provide ready to use ulvan biopolymers, bioactives, nutrients, salts and biogas, conforming a biorefinery approach.

Radical Cascade Annulation of Biphenyl Acrylamides to Dibenzo‐azepinones: Experimental and DFT Studies

AbstractAn efficient method for the conversion of biphenyl acrylamides to dibenzoazepinones with −SCF3 incorporation is described. This operationally simple radical cascade reaction employs CAN as an oxidant and exhibits good functional group tolerance. Substrates featuring −OCH3, −CH3, −Br or −Cl at the para‐position of the aromatic ring exhibits a preference for an ipso‐cyclization due to the intervention of DMSO in the reaction. Density functional theory (DFT) calculations provide valuable insights into the reaction's energetics and product selectivity.

Synthesis of heat-integrated water networks: Integration of heat pumps

A typical heat-integrated water network (HIWN) synthesis problem aims to minimise freshwater and utility consumption while establishing trade-offs between operating and investment costs by exploring different water and heat integration opportunities. Heat integration between hot and cold water streams is performed to save external heating and cooling utilities required to achieve the target temperatures of these streams. This paper proposes a mathematical programming approach to integrate water-to-water heat pumps into the HIWNs. A simple cascade heat pump system with isobutane as a natural working fluid enables a larger temperature lift between the heat pump source and the sink. The objective function of the proposed mixed-integer nonlinear programming (MINLP) model is to minimise the total annualised cost (TAC). The TAC includes operating costs for freshwater, heating/cooling utilities, electricity, and investment in heat exchangers and heat pumps. A sensitivity analysis is performed to evaluate the economic feasibility of the system by varying the heating/electricity cost ratio and depreciation period for the capital investment. The results show that additional utility savings can be obtained by integrating heat pumps into the HIWNs. For threshold problems, a heat pump is feasible for heating/electricity price ratios from 1.175, and heating utility is replaced by electricity for a 1:1 ratio. However, for pinched problems, the feasibility of the heat pump is shifted to lower heating/electricity price ratios, from 0.3 to 0.5, depending on the annualisation factor for the investment.

Solar powered cascade system for sustainable deep-freezing and power generation - exergoeconomic evaluation and multi-objective optimization for tropical regions

The global initiative to decarbonize the refrigeration sector aims to provide cooling energy while reducing CO2 emissions. In India, the majority of urban industrial refrigeration systems are powered by fossil fuel based electricity, which increases consumption of fossil fuel and it contributes to global warming. To address this issue, two unique solar thermal operated cooling configurations, the Simple Cascade System (SCS) and the Recuperative Cascade System (RCS), were designed to fulfil urban industrial cooling energy demands. The surplus electricity generated by these systems is transferred to the on-site grid. Ethane, n-butane, and R1233zd(E) were selected as working fluids due to their low global warming potential (GWP). Among them, the RCS system with R1233zd(E) demonstrated the highest energy and exergy performance, benefiting from its superior thermodynamic properties and effective utilization of internal heat. In New Delhi, the R1233zd(E) operated RCS system achieved the highest cooling and electricity outputs at 54 kW and 20 kW, respectively. Although the R1233zd(E) operated RCS system incurred higher costs, the performance improvement outweighed the increase in cost. To assess the system sustainability in terms of exergy utilisation, a new indicator sustainability index (SI) was developed and established with values of 1.1. Increasing the evaporator temperature enhanced the system performance but also raised total plant cost, while raising the system condenser temperature had the opposite effect. The multi-objective optimization assessment for RCS configuration indicated an optimal objective value of an energy utilization ratio (EUR) of 0.16, an exergy efficiency of 8.7 %, and a capital cost of 20 $/h.

Shorebirds-driven trophic cascade helps restore coastal wetland multifunctionality

Ecosystem restoration has traditionally focused on re-establishing vegetation and other foundation species at basal trophic levels, with mixed outcomes. Here, we show that threatened shorebirds could be important to restoring coastal wetland multifunctionality. We carried out surveys and manipulative field experiments in a region along the Yellow Sea affected by the invasive cordgrass Spartina alterniflora. We found that planting native plants alone failed to restore wetland multifunctionality in a field restoration experiment. Shorebird exclusion weakened wetland multifunctionality, whereas mimicking higher predation before shorebird population declines by excluding their key prey – crab grazers – enhanced wetland multifunctionality. The mechanism underlying these effects is a simple trophic cascade, whereby shorebirds control crab grazers that otherwise suppress native vegetation recovery and destabilize sediments (via bioturbation). Our findings suggest that harnessing the top-down effects of shorebirds – through habitat conservation, rewilding, or temporary simulation of consumptive or non-consumptive effects – should be explored as a nature-based solution to restoring the multifunctionality of degraded coastal wetlands.

Influence of elastic deformation of the blade on the flow field in the blade cascade

Flutter of turbine and compressor blades represents a serious problem for designers of large turbomachines. In real machines, measurements of flutter conditions are hardly possible. Therefore, tests on linear blade cascades with movable blades play important role in investigations of flutter. In the current research, a simple blade cascade for controlled flutter testing was developed. The blades in this test rig undergo high-frequency oscillations which induce inertial forces. The influence of the elastic deformation of the blade on the flow field is studied in this work by means of experiments and numerical simulations. First, the computational and experimental modal analysis was done to obtain eigenfrequencies and modal damping. The deformed shape of the blade due to high-frequency oscillation was acquired by structural transient analysis. The influence of the elastic deformation on the flow field was then studied by CFD analysis for two incidence angles both for the deformed (elastic) and undeformed (idealized rigid) blade. Flow field was only very weakly distorted due to the blade elastic deformation. The total torque induced by aerodynamic and inertial forces was evaluated. The inertial loading is an order of magnitude larger than loading due to fluid flow.

Physico- and biochemical properties of alginates extracted from Ecklonia maxima and Sargassum fluitans using a simple cascade process

Physico- and biochemical properties of alginates extracted from Ecklonia maxima and Sargassum fluitans using a simple cascade process

Synthetic NAD(P)(H) Cycle for ATP Regeneration.

ATP is the energy currency of the cell and new methods for ATP regeneration will benefit a range of emerging biotechnology applications including synthetic cells. We designed and assembled a membraneless ATP-regenerating enzymatic cascade by exploiting the substrate specificities of selected NAD(P)(H)-dependent oxidoreductases combined with substrate-specific kinases. The enzymes in the NAD(P)(H) cycle were selected to avoid cross-reactions, and the cascade was driven by irreversible fuel oxidation. As a proof-of-concept, formate oxidation was chosen as the fueling reaction. ATP regeneration was accomplished via the phosphorylation of NADH to NADPH and the subsequent transfer of the phosphate to ADP by a reversible NAD+ kinase. The cascade was able to regenerate ATP at a high rate (up to 0.74 mmol/L/h) for hours, and >90% conversion of ADP to ATP using monophosphate was also demonstrated. The cascade was used to regenerate ATP for use in cell free protein synthesis reactions, and the ATP production rate was further enhanced when powered by the multistep oxidation of methanol. The NAD(P)(H) cycle provides a simple cascade for the in vitro regeneration of ATP without the need for a pH-gradient or costly phosphate donors.

Radical cascade cyclization for the green and simple synthesis of silylated indolo[2,1-a]isoquinoline derivatives via visible light-mediated Si–H bonds activation

Photocatalytic and photoinduced silyl radicals cascade cyclization procedures for the green and simple preparation of fused tetracyclic skeleton silylated indolo[2,1-a]isoquinoline-6(5H)-ones from 2-aryl-N-acryloyl indoles with hydrosilanes are developed. The photocatalytic reaction is carried out with 9,10-dicyanoanthracene (DCA) as an organophotocatalyst and 3-acetoxyquinuclidine as hydrogen atom transfer (HAT) catalyst at room temperature under metal- and oxidant-free conditions. The keys to the success of photoredox-catalytic conversion include (1) the reductive quenching of DCA* [E1/2(*P/P–) = +1.97 V vs. SCE in MeCN] by 3-acetoxyquinuclidine (Ep = +1.22 V vs. SCE in MeCN), and (2) the thermodynamic feasibility of hydrogen atom abstraction from hydridic Si–H bond by electrophilic N+•. Particularly, the simple photoinduced cascade cyclization using (TMS)3SiH with 2-aryl-N-acryloyl indoles was exploited via an electron−donor−acceptor (EDA) complex under visible light irradiation.

Quickest Inference of Network Cascades With Noisy Information

We study the problem of estimating the source of a network cascade given a time series of noisy information about the spread. Initially, there is a single vertex affected by the cascade (the source) and the cascade spreads in discrete time steps across the network. The cascade evolution is hidden, but one can observe a time series of noisy signals from each vertex. The time series of a vertex is assumed to be a sequence of i.i.d. samples from a pre-change distribution $Q_0$ before the cascade affects the vertex, and the time series is a sequence of i.i.d. samples from a post-change distribution $Q_1$ once the cascade has affected the vertex. Given the time series of noisy signals, which can be viewed as a noisy measurement of the cascade evolution, we aim to devise a procedure to reliably estimate the cascade source as fast as possible. We investigate Bayesian and minimax formulations of the source estimation problem, and derive near-optimal estimators for simple cascade dynamics and network topologies. In the Bayesian setting, an estimator which observes samples until the error of the Bayes-optimal estimator falls below a threshold achieves optimal performance. In the minimax setting, optimal performance is achieved by designing a novel multi-hypothesis sequential probability ratio test (MSPRT). We find that these optimal estimators require $\log \log n / \log (k - 1)$ observations of the noisy time series when the network topology is a $k$-regular tree, and $(\log n)^{\frac{1}{\ell + 1}}$ observations are required for $\ell$-dimensional lattices. Finally, we discuss how our methods may be extended to cascades on arbitrary graphs.

Nitro-Spirocyclization of Biaryl Ynones with tert-Butyl Nitrite: Access to NO2-Substituted Spiro[5,5]trienones.

A metal/peroxide-free involved simple cascade 6-exo-trig spirocyclization of tert-butyl nitrite with biaryl ynones has been finished, which resulted in various NO2-modified spiro[5,5]trienones with good regioselectivity/yields. A variety of scaled-up experiments, reduction/epoxidation operations, and mechanistic studies were performed to verify the merits and spirocyclization process of this radical system. Finally, the structure of the spirocycles was confirmed by single-crystal X-ray diffraction.

Transition‐Metal‐Free One‐Pot [3+3] Heteroannulative Coupling of Thioamides with Epichlorohydrin: Access to Diverse 1,3‐Thiazinanes

AbstractAn operationally simple and efficient cascade approach to access a series of 1,3‐thiazinanes has been developed through intermolecular [3+3] heteroannulative coupling employing β‐ketothioamide as a C1 N1S1 unit and epichlorohydrin as a C3 unit at room temperature for the first time. The reaction proceeds by nucleophilic attack of thiocarbonyl sulfur to less hindered primary carbon of oxirane followed by sequential intramolecular N‐cyclization and dehydrochlorination enabling the coupling by cleavage of C−O bond and formation of two new C−S and C−N bonds in one stretch. This protocol not only avoids potential toxicity and tedious work up procedures, but also features open atmosphere, good to high yields, gram‐scalability, and easy performance from inexpensive, readily available starting materials under transition‐metal‐free conditions. A probable mechanism for the formation of 1,3‐thiazinanes has been suggested.

Computationally Lightweight Hyperspectral Image Classification Using a Multiscale Depthwise Convolutional Network With Channel Attention

Convolutional networks have been widely used for the classification of hyperspectral images; however, such networks are notorious for their large number of trainable parameters and high computational complexity. Additionally, traditional convolution-based methods are typically implemented as a simple cascade of a number of convolutions using a single-scale convolution kernel. In contrast, a lightweight multiscale convolutional network is proposed, capitalizing on feature extraction at multiple scales in parallel branches followed by feature fusion. In this approach, 2D depthwise convolution is used instead of conventional convolution in order to reduce network complexity without sacrificing classification accuracy. Furthermore, multiscale channel attention is also employed to selectively exploit discriminative capability across various channels. To do so, multiple 1D convolutions with varying kernel sizes provide channel attention at multiple scales, again with the goal of minimizing network complexity. Experimental results reveal that the proposed network not only outperforms other competing lightweight classifiers in terms of classification accuracy but also exhibits a lower number of parameters as well as significantly less computational cost.

ConvTransNet: A CNN–Transformer Network for Change Detection With Multiscale Global–Local Representations

Change detection (CD) in optical remote sensing images has significantly benefited from the development of deep convolutional neural networks (CNNs) due to their strong capability of local modeling in bi-temporal images. In addition, the recent rise of transformer modules leads to the improvement of global feature extraction of bi-temporal remote sensing images. Note that the existing simple cascade of deep CNNs and transformer modules shows limited CD performance on small changed areas due to deficiencies of multi-scale information therein. To address the aforementioned issue, we propose a new CNN-transformer network (ConvTransNet) with multi-scale framework to better exploit global-local information in optical remote sensing images. In our ConvTransNet, we propose the parallel-branch ConvTrans block as the basic component to generate global-local features, i.e., adaptively integrates the global features summarized by a transformer-based branch and the local features extracted by a convolution-based branch, providing better identifiability between changed areas and unchanged areas. By fusing multiple global-local features with different scales, our ConvTransNet improves the robustness of the CD performance on changed areas with different sizes, especially small changed areas. Experiments on two public change detection datasets of optical remote sensing images, i.e., LEVIR-CD and CDD, demonstrate that our ConvTransNet achieves enhanced CD performance than the other commonly used methods.

RGB-Induced Feature Modulation Network for Hyperspectral Image Super-Resolution

Super-resolution (SR) is one of the powerful techniques to improve image quality for low-resolution (LR) hyperspectral image (HSI) with insufficient detail and noise. Traditional methods typically perform simple cascade or addition during the fusion of the auxiliary high-resolution RGB and LR HSI. As a result, the abundant HR RGB details are not utilized as a priori information to enhance the HSI feature representation, leaving room for further improvements. To address this issue, we propose an RGB-induced feature modulation network for HSI SR (IFMSR). Considering that similar patterns are common in images, a multi-corresponding patch aggregation is designed to globally assemble this contextual information, which is beneficial for feature learning. Besides, to adequately exploit plentiful HR RGB details, an RGB-induced detail enhancement (RDE) module and a deep cross-modality feature modulation (CFM) module are proposed to transfer the supplementary materials from RGB to HSI. These modules can provide a more direct and instructive representation, leading to further edge recovery. Experiments on several datasets demonstrate that our approach achieves comparable performance under more realistic degradation condition. Our code is publicly available at https://github.com/qianngli/IFMSR.

Bismuth(III)-catalyzed cascade condensation of alkynyl alcohols with terminal alkynes: A facile construction of propargyl cyclic ethers

Herein, we report a Bi(OTf)3-catalyzed cascade condensation between alkynols (particularly pent-4-yn-1-ols and hex-5-yn-1-ols) and terminal alkynes (aryl alkynes) to facile access to diverse propargyl cyclic ethers (2‑alkynyl tetrahydrofurans and 2‑alkynyl tetrahydropyrans). This simple and efficient cascade transformation proceeds through initial intramolecular hydroalkoxylation of alkynols to give corresponding cyclic enol ethers (via exo-dig or endo-dig mode of ring-closure) followed by hydroalkynylation. Cost-effective, naturally abundant, green Lewis acid catalysis, ambient reaction conditions, short reaction times, good substrate scope, and high yields are salient features of this strategy.

Radiative cooling of polyyne anions: C4H- and C6H.

Time-dependent photodetachment action spectra for the linear hydrocarbon anions C4H- and C6H- are investigated using the cryogenic Double ElectroStatic Ion Ring ExpEriment. The radiative cooling characteristics of these ions on the millisecond to seconds timescale are characterized by monitoring changes in their spectra as the ions cool by spontaneous infrared (IR) emission. The average cooling rates, extracted using Non-negative Matrix Factorization, are fit with 1/e lifetimes of 19 ± 2 and 3.0 ± 0.2s for C4H- and C6H-, respectively. The cooling rates are successfully reproduced using a simple harmonic cascade model of IR emission. The ultraslow radiative cooling dynamics determined in this work provide important data for understanding the thermal cooling properties of linear hydrocarbon anions and for refining models of the formation and destruction mechanisms of these anions in astrochemical environments.

Regio- and Chemoselective Access to Dihydrothiophenes and Thiophenes via Halogenation/Intramolecular C(sp2)-H Thienation of α-Allyl Dithioesters at Room Temperature.

An operationally simple, practical, and efficient cascade approach employing α-allyl dithioesters and NBS/NIS has been achieved to access a series of dihydrothiophenes and thiophenes containing diverse functional groups of different electronic and steric natures in good to excellent yields at room temperature in open air. The reaction proceeds via the electrophilic addition of a halogen source (NBS/NIS) to an allylic double bond, followed by intramolecular regio- and chemoselective S-cyclization. This protocol avoids potential toxicity and tedious work-up conditions, and features easy synthesis from readily available starting materials under catalyst-free conditions. Furthermore, 4,5-dihydrothiophenes were aromatized to thiophenes by treatment with KOH in DMF at room temperature. A probable mechanism for the formation of dihydrothiophenes and thiophenes from α-allyl dithioesters has been suggested. Notably, a large-scale experiment and the transformations of products indicated the potential utility of this reaction compared to competing processes for the synthesis of 4,5-dihydrothiophenes and thiophenes.

ZnCl2 catalyzed cascade conjugative alkynylation/6-endo-dig cyclisation of N,N-dimethyl barbituric acid derived alkenes under ultrasonic irradiation: An improved, base & column-free access to pyrano[2,3-d]pyrimidine-2,4(3H,5H)-diones

A simple and efficient cascade pathway for the synthesis of pyrano[2,3-d]pyrimidine-2,4(3H,5H)-diones by the reaction of N,N-dimethyl barbituric acid, aromatic aldehydes and terminal alkynes using ultrasonic irradiation as the energy source has been developed. The methodology describes the first use of easily accessible ZnCl2 in alkynylide formation leading to multicomponent synthesis of the heterocycle. Additionally, the final products are obtained by recrystallization from hot ethanol without involving the laborious and solvent consuming chromatographic techniques. The proposed mechanistic pathway has been studied with Density Functional Theory and the compounds synthesized are characterized with SC-XRD, 1H NMR 13C NMR, and HRMS analysis.