A novel photo-triggered self-catalyzed fluoroalkylation/cyclization of quinazolinones containing unactivated alkenes with various fluoroalkyl bromides has been developed. This transformation exhibits ...excellent substrate generality with respect to both the coupling partners. Of note is that this is the first example describing the Csp3–Br bond homolysis of alkyl bromides via a substrate (quinazolinones) induced energy transfer process. Additionally, the mild conditions, tolerance to a wide range of functional groups and operational simplicity make this protocol practical for the synthesis of fluorine-containing ring-fused quinazolinones.
In this work, a high thermoelectric figure of merit, zT of 1.9 at 740 K is achieved in Ge
Bi
Te crystals through the concurrent of Seebeck coefficient enhancement and thermal conductivity reduction ...with Bi dopants. The substitution of Bi for Ge not only compensates the superfluous hole carriers in pristine GeTe but also shifts the Fermi level (E
) to an eligible region. Experimentally, with moderate 6-10% Bi dopants, the carrier concentration is drastically decreased from 8.7 × 10
cm
to 3-5 × 10
cm
and the Seebeck coefficient is boosted three times to 75 μVK
. In the meantime, based on the density functional theory (DFT) calculation, the Fermi level E
starts to intersect with the pudding mold band at L point, where the band effective mass is enhanced. The enhanced Seebeck coefficient effectively compensates the decrease of electrical conductivity and thus successfully maintain the power factor as large as or even superior than that of the pristine GeTe. In addition, the Bi doping significantly reduces both thermal conductivities of carriers and lattices to an extremely low limit of 1.57 W m
K
at 740 K with 10% Bi dopants, which is an about 63% reduction as compared with that of pristine GeTe. The elevated figure of merit observed in Ge
Bi
Te specimens is therefore realized by synergistically optimizing the power factor and downgrading the thermal conductivity of alloying effect and lattice anharmonicity caused by Bi doping.
•First attempt to investigate store brand impacts on multiple-echelon supply chains.•Firms’ strategic interactions differ significantly under three-echelon channel.•Store brand can change nature of ...manufacturer-distributer strategic interaction.•Distributer may act as a buffer between manufacturer and retailer with store brand.•All channel members might even benefit from store brand introduction.
Observing that store brands are often introduced in multiple-echelon supply chains, however, the common wisdom from analytical models on store brands has been obtained from two-echelon supply chains, we investigate the strategic interaction in a three-echelon supply chain (manufacturer-distributer-retailer) with a store brand and its corresponding impacts. This research reveals the ways in which store brand affects the interaction and performance of the three-echelon supply chain, as it is significantly different from the two-echelon case. In particular, when the store brand is moderately competitive, the nature of the interaction between the national-brand manufacturer and the distributer can change from dependence to independence, enabling the national-brand manufacturer to manipulate its price leadership to increase its wholesale price instead, leaving the distributer itself to deter the SB introduction. Consequently, the distributer plays a special role as a buffer between the national-brand manufacturer and the retailer. When the store brand is competitive enough and finally introduced, all channel members may benefit from the store brand introduction, but this phenomenon never occurs in the two-echelon case under the same conditions. Therefore, this study increases our understanding of how store brand affects the multiple-echelon supply chain and provides another important theoretical explanation for why executive managers of national brand products need not overreact to the introduction of their retailers’ store brands.
Recently, numerous unsupervised cross-modal hashing methods have been proposed to deal the image-text retrieval tasks for the unlabeled cross-modal data. However, when these methods learn to generate ...hash codes, almost all of them lack modality-interaction in the following two aspects: (1) The instance similarity matrix used to guide the hashing networks training is constructed without image-text interaction, which fails to capture the fine-grained cross-modal cues to elaborately characterize the intrinsic semantic similarity among the datapoints. (2) The binary codes used for quantization loss are inferior because they are generated by directly quantizing a simple combination of continuous hash codes from different modalities without the interaction among these continuous hash codes. Such problems will cause the generated hash codes to be of poor quality and degrade the retrieval performance. Hence, in this paper, we propose a novel Unsupervised Cross-modal Hashing with Modality-interaction, termed UCHM. Specifically, by optimizing a novel hash-similarity-friendly loss, a modality-interaction-enabled (MIE) similarity generator is first trained to generate a superior MIE similarity matrix for the training set. Then, the generated MIE similarity matrix is utilized as guiding information to train the deep hashing networks. Furthermore, during the process of training the hashing networks, a novel bit-selection module is proposed to generate high-quality unified binary codes for the quantization loss with the interaction among continuous codes from different modalities, thereby further enhancing the retrieval performance. Extensive experiments on two widely used datasets show that the proposed UCHM outperforms state-of-the-art techniques on cross-modal retrieval tasks.
Energy and fresh water are essential for the sustainable development of human society, and both could be obtained from seawater. Herein, we explored the first covalent organic framework (COF) sponge ...(named BHMS) by in situ loading the benzoxazole-linked COF (DBD-BTTH) onto a porous polymer scaffold (polydimethylsiloxane) as a synergistic platform for efficient solar desalination and selective uranium recovery. In natural seawater, BHMS shows a high evaporation rate (1.39 kg m–2 h–1) and an exceptional uranium recovery capacity (5.14 ± 0.15 mg g–1) under 1 sun, which are due to its desirable inbuilt structural hierarchy and elastic macroporous open cells providing adequate water transport, increased evaporation sites of seawater, and selective binding sites of uranyl. Besides, the excellent photothermal performance and photocatalytic activity endow the BHMS with high solar desalination efficiency and excellent anti-biofouling activity and promote selective coordination of uranyl.
In this paper, a new anticipation optimal velocity model (AOVM) is proposed by considering anticipation effect on the basis of the full velocity difference model (FVDM) for car-following theory on ...single lane. The linear stability condition is derived from linear stability analysis. Starting and braking process is investigated for the car motion under a traffic signal, which shows that the results accord with empirical traffic values. Especially AOVM can avoid the disadvantage of the unrealistically high deceleration appearing in FVDM. Furthermore, numerical simulation shows that AOVM might avoid the disadvantage of negative velocity and headway that occur at small sensitivity coefficients in the FVDM since the anticipation effect is taken into account in AOVM, which means that collision disappears with the consideration of an appropriate anticipation parameter.
•A new anticipation optimal velocity car-following model is proposed.•The anticipation effects on the stability of traffic flow have been explored.•The starting and braking process were carried out through simulation.•The anticipation effects of the optimal velocity can avoid the disadvantage of negative velocity.
Mercury is one of the most toxic elements in the environment. Recently, a number of covalent organic frameworks (COFs) were developed for simultaneous detection and removal of mercury. They rely on ...post-synthetically modified sulfur-based ligands for irreversible mercury binding. In addition, their rigid structures resulted in low fluorescence yields. Herein, a novel highly luminescent COF named TFPPy-CHYD with a quantum yield of 13.6% was designed by integrating a pyrene-based building block with a flexible carbohydrazide linker. The nitrogen-based ligand allows reversible and highly selective binding of Hg2+. As a sensing platform, it has an ultralow detection limit of 17 nM mercury. More importantly, TFPPy-CHYD exhibits excellent performance in removing mercury from both air and water, providing very high Hg0 and Hg2+ adsorption capacities of 232 and 758 mg g–1, respectively. This work demonstrates enormous potential of luminescent COF for metal detection and remediation. By rational introducing metal ligands, a suite of new COF materials might be synthesized for the detection and removal of other metal ions.
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•Dilute NaOH supplemented with H2O2 pretreatment was successfully employed to GW.•The pretreated GW showed high holocellulose recovery under mild condition.•The process exhibited ...synergistic effect on lignin removal and enzymolysis.•High titers of ethanol from the pretreated GW was achieved by SSCF.
Pretreatment process plays a key role in biofuel production from lignocellulosic feedstocks. A study on dilute NaOH pretreatment supplemented with H2O2 under mild condition was conducted to overcome the recalcitrance of grass waste (GW). The optimized process could selectively increase lignin removal (73.2%), resulting in high overall recovery of holocellulose (73.8%) as well as high enzymolysis efficiency (83.5%) compared to H2O2 or NaOH pretreatment. The analyses by Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) revealed that supplementary H2O2 disrupted the structure of GW to facilitate the removal of lignin by NaOH, and exhibited synergistic effect on lignin removal and enzymolysis with dilute NaOH. Moreover, high titer of ethanol (100.7 g/L) was achieved by SSCF on 30% (w/v) pretreated GW loading. The present study suggests that the established synergistic pretreatment is a simple, efficient, and promising process for GW biorefinery.
Due to their high retrieval efficiency and low storage cost, cross-modal hashing methods have attracted considerable attention. Generally, compared with shallow cross-modal hashing methods, deep ...cross-modal hashing methods can achieve a more satisfactory performance by integrating feature learning and hash codes optimizing into a same framework. However, most existing deep cross-modal hashing methods either cannot learn a unified hash code for the two correlated data-points of different modalities in a database instance or cannot guide the learning of unified hash codes by the feedback of hashing function learning procedure, to enhance the retrieval accuracy. To address the issues above, in this paper, we propose a novel end-to-end Deep Cross-Modal Hashing with Hashing Functions and Unified Hash Codes Jointly Learning (DCHUC). Specifically, by an iterative optimization algorithm, DCHUC jointly learns unified hash codes for image-text pairs in a database and a pair of hash functions for unseen query image-text pairs. With the iterative optimization algorithm, the learned unified hash codes can be used to guide the hashing function learning procedure; Meanwhile, the learned hashing functions can feedback to guide the unified hash codes optimizing procedure. Extensive experiments on three public datasets demonstrate that the proposed method outperforms the state-of-the-art cross-modal hashing methods.
Parasitic copepods are frequently discovered in many marine animals, and they exhibit great species diversity with remarkable morphological adaptations to their parasitic lifestyle. Similar to their ...free-living relatives, parasitic copepods usually develop through complex life cycle, but they eventually transform into a modified adult form with reduced appendages. Although the life cycle and distinct larval stages have been described in a few species of parasitic copepods, particularly those infecting commercially valuable marine animals (such as fishes, oysters, and lobsters), very little is known about the developmental process of the species that transformed into extremely simplified adult body plan. This paucity also causes some difficulties when investigating the taxonomy and phylogeny of this kind of parasitic copepods. Here we describe the embryonic development and a series of sequential larval stages of a parasitic copepod, Ive ptychoderae, which is a vermiform endoparasite living inside the hemichordate acorn worms. We devised laboratory regimes that enable us raising large quantity of embryos and free living larvae, and obtaining post-infested I. ptychoderae samples from the host tissues. Using defined morphological features, the embryonic development of I. ptychoderae can be categorized into eight stages (1-, 2-, 4-, 8-, 16- cell stages, blastula, gastrula, and limb bud stages) and the post-embryonic development comprises six larval stages (2 naupliar and 4 copepodid stages). Based on the comparisons of morphological characters in the nauplius stage, our results provide evidence to support that the Ive-group is more closely related to the Cyclopoida, which represents one of the two major clades that contain many highly transformed parasitic copepods. Thus, our results help to resolve the problematic phylogenetic position of the Ive-group in previous study based on analysis using 18S rDNA sequences. Combining with more molecular data, future comparative analyses on the morphological features of copepodid stages will further refine our understanding of the phylogenetic relationships of parasitic copepods.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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