Distributed Denial of Service (DDoS) attacks in cloud computing environments are growing due to the essential characteristics of cloud computing. With recent advances in software-defined networking ...(SDN), SDN-based cloud brings us new chances to defeat DDoS attacks in cloud computing environments. Nevertheless, there is a contradictory relationship between SDN and DDoS attacks. On one hand, the capabilities of SDN, including software-based traffic analysis, centralized control, global view of the network, dynamic updating of forwarding rules, make it easier to detect and react to DDoS attacks. On the other hand, the security of SDN itself remains to be addressed, and potential DDoS vulnerabilities exist across SDN platforms. In this paper, we discuss the new trends and characteristics of DDoS attacks in cloud computing, and provide a comprehensive survey of defense mechanisms against DDoS attacks using SDN. In addition, we review the studies about launching DDoS attacks on SDN, as well as the methods against DDoS attacks in SDN. To the best of our knowledge, the contradictory relationship between SDN and DDoS attacks has not been well addressed in previous works. This work can help to understand how to make full use of SDN's advantages to defeat DDoS attacks in cloud computing environments and how to prevent SDN itself from becoming a victim of DDoS attacks, which are important for the smooth evolution of SDN-based cloud without the distraction of DDoS attacks.
Objective: Detection rate and isolation yield of circulating tumor cell(CTC) are low in squamous cell carcinoma of head and neck(SCCHN) with in vitro approaches due to limited sample volumes. In this ...study, we applied the Cell Collector to capture CTC in vivo from peripheral blood.Methods: In total, the study included 22 cases with 37 times of detection. All of the patients were newly diagnosed with locally advanced or metastatic SCCHN, including laryngocarcinoma(40.9%, 9/22) and hypopharyngeal carcinoma(59.1%, 13/22). All patients received CTC analysis before treatment. Three patients received induction chemotherapy. Sixteen patients received surgical therapy, of which 13 patients received postoperative detection. Two patients received both induction chemotherapy and surgery treatment. Patients underwent two successive Cell Collector applications 24 h before and 7 d after surgical therapy. Nine healthy volunteers were enrolled as the control group. Epidermal growth factor receptor variant type Ⅲ(EGFRⅧ)expression was analyzed with fluorescent dye labeled antibody.Results: With Cell Collector isolation, 72.7%(16/22) of the patients were positive for ≥1 CTC(CTC; range,1–17 cells) before treatments and 46.7%(7/15) of patients were CTC positive for ≥1 CTC(CTC; range, 1–29 cells) after surgical therapy. Moreover, the detection rate of Cell Collector(82.4%, 14/17; CTC count range, 0–17)in advanced SCCHN(stage Ⅲ–Ⅳ) was much higher than that in early stages(stage Ⅰ–Ⅱ, 40.0%, 2/5; CTC count range, 0–2)(P<0.05). EGFRⅧ expression of CTC was also analyzed with fluorescence staining. One CTCEGFRⅧ-positive patient was detected from six CTC-positive patients, and the positive expression of EGFRⅧ was also found in the tumor tissue of this patient.Conclusions: In vivo detection of CTCs had high sensitivity in SCCHN, which might improve CTC application in clinic.
The Industrial Internet of Things is growing fast. But the rapid growth of IIoT devices raises a number of security concerns, because the IIoT device is weak in defending against malware, and the ...method of managing a large number of IIoT devices is awkward and inconvenient. This article proposes a multi-level DDoS mitigation framework (MLDMF) to defend against DDoS attacks for IIoT, which includes the edge computing level, fog computing level, and cloud computing level. Software defined networking is used to manage a large number of IIoT devices and to mitigate DDoS attacks in IIoT. Experimental results show the effectiveness of the proposed framework.
Stable F-T-based catalyst development in direct CO hydrogenation to higher alcohols is still a challenge at present. In this study, CuFe/SiO2 catalysts with a SiO2 support treated with a piranha ...solution were prepared and evaluated in a long-term reaction. The treated catalyst showed higher total alcohols’ selectivity and great stability during a reaction of more than 90 h. It was found that the treatment with the piranha solution enriched the surface hydroxyl groups on SiO2, so that the Cu–Fe active components could be firmly anchored and highly dispersed on the support, resulting in stable catalytic performance. Furthermore, the in situ DRIFTS revealed that the adsorption strength of CO on Cu+ on the treated catalyst surface was weakened, which made the C-O bond less likely to be cleaved and thus significantly inhibited the formation of hydrocarbon products. Meanwhile, the non-dissociated CO species were obviously enriched on the Cu0 surface, promoting the formation of alcohol products, and thus the selectivity of total alcohols was increased. This strategy will shed light on the design of supported catalysts with stabilized structures for a wide range of catalytic reactions.
Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease exhibiting the poorest prognosis among solid tumors. The efficacy of conventional therapies has been hindered largely due to the ...insufficient chemotherapeutic delivery to the dense desmoplastic tumor stroma, and the extremely high or toxic dose needed for chemotherapy. Traditional Chinese Medicine (TCM) contains effective components that can effectively regulate tumor microenvironment and kill tumor cells, providing promising alternatives to PDAC chemotherapy. In this study, two active drug monomers of TCM were screened out and a sequentially targeting delivery regimen was developed to realize the optimized combinational therapy. Transforming growth factor-β (TGF-β) plays an indispensable role in promoting cancer-associated fibroblasts (CAFs) activation and proliferation, and CAFs have caused major physical barriers for chemotherapeutic drug delivery. Herein, CAFs-targeting biodegradable polymer nanoparticle (CRE-NP(α-M)) coated with CREKA peptide and loaded with TCM α-mangostin (α-M) was developed to modulate tumor microenvironment by interfering of TGF-β/Smad signaling pathway. Low pH-triggered micelle modified with CRPPR peptide and loaded with another TCM triptolide was constructed to increase the therapeutic effect of triptolide at the tumor sites and reduced its damage to main organs. As expected, CRE-NP(α-M) effectively inactived CAFs, reduced extracellular matrix production, promoted tumor vascular normalization and enhanced blood perfusion at the tumor site. The sequentially targeting drug delivery regimen, CRP-MC(Trip) following CRE-NP(α-M) pretreatment, exhibited strong tumor growth inhibition effect in the orthotopic tumor model. Hence, sequentially targeting delivery of nanoformulated TCM offers an efficient approach to overcome the permeation obstacles and improve the effect of chemotherapy on PDAC, and provides a novel option to treat desmoplastic tumors.
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•Polyphenolic α-Mangostin inactives CAFs, normalizes tumor vascular, and enhances blood perfusion through TGF-β/Smad.•Acidity sensitive micelles serve as ideal carrier for triptolide with lower toxicities and higher efficacy at minor dose.•Regimen of sequentially targeting delivery of nanoformulated TCM exhibits superior therapeutic effects in PDAC treatment.•Drug carriers are biodegradable and non-toxic.
Owing to distinct physicochemical properties in comparison to gold and silver counterparts, atomically precise copper nanoclusters are attracting embryonic interest in material science. The ...introduction of copper cluster nanomaterials in more interesting fields is currently urgent and desired. Reported in this work are novel copper nanoclusters of XCu54Cl12(tBuS)20(NO3)12 (X=S or none, tBuSH=2‐methyl‐2‐propanethiol), which exhibit high performance in photothermal conversion. The clusters have been prepared in one pot and characterized by combinatorial techniques including ultraviolet‐visible spectroscopy (UV‐vis), electrospray ionization mass spectrometry (ESI‐MS), and X‐ray photoelectron spectroscopy (XPS). The molecular structure of the clusters, as revealed by single crystal X‐ray diffraction analysis (SCXRD), shows the concentric three‐shell Russian doll arrangement of X@Cu14@Cl12@Cu40. Interestingly, the SCu54Cl12(tBuS)20(NO3)12 cluster contains 8 free valence electrons in its structure, making it the first eight‐electron copper nanocluster stabilized by thiolates. More impressively, the clusters possess an effective photothermal conversion (temperature increases by 71 °C within ~50 s, λex=445 nm, 0.5 W cm−2) in a wide wavelength range (either blue or near‐infrared). The photothermal conversion can be even driven under irradiation of simulated sunlight (3 sun), endowing the clusters with great potency in solar energy utilization.
Atomically precise Cu54 nanoclusters with eight free valence electrons have been prepared, characterized, and structurally determined. The clusters show high performance in the field of photothermal conversion. For the first time, atomically precise copper nanoclusters are proved to be effective in photothermal application, which may stimulate the research on using copper nanoclusters in material sciences.
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•The effect of water on mixed alcohols synthesis from syngas was investigated.•The evolution of surface species was revealed by in situ DRIFTS.•Only formate species were enriched via ...the regeneration of OH from water.•Methanol formation was enhanced while isobutanol was little influenced by water.
Water is an inevitable by-product in the process of CO/CO2 hydrogenation to downstream chemicals. However, the role of water for mixed alcohols synthesis has been rarely reported so far. Herein, the effect of water was studied on the reaction path itself using a typical ZnCr catalyst, whose structure remained unchanged even after water treatment. It was found that the intentional introduction of water into the reaction system enhanced the space–time yield (STY) of methanol, whereas that of isobutanol was almost unchanged. In situ DRIFTS technique was employed to simulate the whole reaction process and revealed that water only promoted the formation of methanol’s precursors (formate species), but did not promote the production of isobutanol’s precursors (C2 intermediates that formed by formyl species combining with molecularly adsorbed CO species). These findings may enrich the understanding of the formation mechanism of mixed alcohols synthesis.
Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process that regulates the localization ...of many macromolecules within the nuclear or cytoplasmic compartments. In humans, approximately 60 proteins are involved in nuclear transport, including nucleoporins that form membrane-embedded nuclear pore complexes, karyopherins that transport cargoes through these complexes, and Ran system proteins that ensure directed and rapid transport. Many of these nuclear transport proteins play additional and essential roles in mitosis, biomolecular condensation, and gene transcription. Dysregulation of nuclear transport is linked to major human diseases such as cancer, neurodegenerative diseases, and viral infections. Selinexor (KPT-330), an inhibitor targeting the nuclear export factor XPO1 (also known as CRM1), was approved in 2019 to treat two types of blood cancers, and dozens of clinical trials of are ongoing. This review summarizes approximately three decades of research data in this field but focuses on the structure and function of individual nuclear transport proteins from recent studies, providing a cutting-edge and holistic view on the role of nuclear transport proteins in health and disease. In-depth knowledge of this rapidly evolving field has the potential to bring new insights into fundamental biology, pathogenic mechanisms, and therapeutic approaches.
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•The appropriate La dopant improve the formation of oxygen vacancy sites.•The introduction of La into the ZnCr catalyst promoted the formation and stability of the formate ...intermediate.•The doping of La promoter favored the isobutanol synthesis.
A series of catalysts were designed and synthesized via doping lanthanum into ZnCr oxide to realize efficient synthesis of isobutanol from syngas. By applying a combination of characterizations (XRD, TEM, EPR, XPS and in situ FT-IR) and DFT calculations, the effects of lanthanum promoter on catalyst structure and catalytic performance were investigated. With the doping of lanthanum, ZnCrLax composite oxides with a novel catalyst structure were constructed, in which Zn atom at tetrahedron site was partly substituted by doping La atom. The presence of this structure enhanced the formation of more oxygen vacancy sites and further benefitted the CO activation. In addition, formate intermediate was easier to generate and exhibited superior stability over ZnCrLax surface thus leaded to remarkably promoted catalytic activity. The ZnCrLa0.05 catalyst achieved optimum total alcohols selectivity of 61%, and the fraction of isobutanol reached as high as 24.6% under CO conversion of 23%.
Polyurethane (PU) materials with high strength, toughness, anti‐wear properties, and high heat resistance are in high demand for dynamic sealing applications. In this study, a series of ...high‐performance crosslinking polyurethanes (CPUs) were prepared by pre‐polymerization of polycarbonate diol (PCDL) with toluene‐2,4‐diisocyanate (TDI), followed by crosslinking with trimethylolpropane (TMP). The molar ratio (R) of PCDL/ TDI and the degree of cross‐linking were found to significantly affect the microphase separation. The results indicate that as the R‐value increases, the transition temperature of CPUs increases from 6.0°C to 82.4°C, and the tensile strength increases from 21.1 ± 2.5 MPa to 46.0 ± 3.6 MPa. Moreover, the CPUs exhibit excellent heat resistance (with a heat resistance index of ~150°C) and hydrolysis resistance, attributed to the high crystallinity of PCDL and the synergistic effect of chemical crosslinking. Additionally, the CPUs demonstrate low friction coefficient (COF = 0.01–0.062), exceptional anti‐wear properties (Akron wear, 0.11–0.07 cm3/1.61 km), and outstanding fatigue resistance. These desirable characteristics make CPUs suitable for use as dynamic sealing or lubricating materials in harsh conditions, thereby extending the service life of seals and preventing leakage and other related issues.
In this study, a series of high‐performance crosslinking polyurethanes (CPUs) were synthesized. The synthesis involved pre‐polymerization of polycarbonate diol (PCDL) with toluene‐2,4‐diisocyanate (TDI), followed by crosslinking with trimethylolpropane (TMP). The molar ratio (R) of PCDL/TDI and the degree of cross‐linking were observed to have a significant impact on the microphase separation. The results indicate that as the R‐value increases, the transition temperature of CPUs and the tensile strength also increase. Additionally, the CPUs demonstrate excellent heat resistance, hydrolysis resistance, and exceptional anti‐wear properties. These properties can be attributed to the high crystallinity of PCDL and the synergistic effect of chemical crosslinking.
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