216 research outputs found

    Simple direct formation of self-assembled N-heterocyclic carbene monolayers on gold and their application in biosensing

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    CRL acknowledges the Engineering and Physical Sciences Research Council (UK) for the funding of his PhD studentship (EP/M506631).The formation of organic films on gold employing N-heterocyclic carbenes (NHCs) has been previously shown to be a useful strategy for generating stable organic films. However, NHCs or NHC precursors typically require inert atmosphere and harsh conditions for their generation and use. Herein we describe the use of benzimidazolium hydrogen carbonates as bench stable solid precursors for the preparation of NHC films in solution or by vapour-phase deposition from the solid state. The ability to prepare these films by vapour-phase deposition permitted the analysis of the films by a variety of surface science techniques, resulting in the first measurement of NHC desorption energy (158±10 kJ mol−1) and confirmation that the NHC sits upright on the surface. The use of these films in surface plasmon resonance-type biosensing is described, where they provide specific advantages versus traditional thiol-based films.Publisher PDFPeer reviewe

    Ivan Lupić i Bojana Schubert: Prvi hrvatski Shakespeare, Pučko otvoreno učilište »Dragutin Novak«, Ludbreg, 2016., 111 str.

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    The work was supported by EPSRC (EP/E061303/1 and EP/L017008/1). ADF acknowledges support from EPSRC (EP/I004602/1).The electrochemical deposition of Au onto Au substrates modified by self-assembled monolayers (SAMs) was studied by linear sweep voltammetry (LSV), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Patterned SAMs exhibiting electrochemical contrast were prepared by two different methods. One used microcontact printing (μCP) to generate a binary SAM of ω-(4'-methyl-biphenyl-4-yl)-propane thiol (CH3-C6H4-C6H4-(CH2)3-SH, MBP3) and octadecane thiol (CH3(CH2)17SH, ODT). Templated by the SAM, a gold microelectrode structure was electrodeposited featuring a line 15 μm wide and 3 mm long. After transfer to an epoxy substrate the structure proved to be electrically conductive across the full length. The other patterning method applied electron beam lithography (EBL) where electrochemical contrast was achieved by crosslinking molecules in a single component SAM of MBP3. An electron dose above 250 mC/cm2 results in a high deposition contrast. The choice of parameters for the deposition/lift-off process is found to be more critical for Au compared to Cu studied previously. The origin of the differences and implications for nanoscale patterning are discussed.PostprintPeer reviewe

    Low transthyretin is associated with the poor prognosis of colorectal cancer

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    ObjectiveTo determine whether transthyretin (TTR) influences the prognosis of patients with colorectal cancers and establish a predictive model based on TTR.MethodsBetween January 2013 and February 2019, the clinical data of 1322 CRC patients aged from 18 years to 80 years who underwent surgical treatment were retrospectively analyzed. The preoperative TTR level, clinicopathological data, and follow-up data were recorded. The X-tile program was used to determine the optimal cut-off value. Cox proportional hazard regression analysis was conducted to evaluate the correlation between the TTR and the cumulative incidence of cancer-specific survival (CSS). Nomograms were then developed to predict CSS. Furthermore, an additional cohort of 377 CRC patients enrolled between January 2014 and December 2015 was included as an external validation.ResultsBased on the optimal cut-off value of 121.3 mg/L, we divided the patients into the TTR-lower group (<121.3 mg/L) and the TTR-higher group (≥121.3 mg/L). Comparative analysis revealed that the TTR-higher group exhibited a younger demographic, a higher prevalence of low colorectal cancers, an elevated R0 resection rate, superior differentiation, earlier stage and lower levels of carcinoembryonic antigen (CEA) in contrast to the TTR-lower group. The Cox multivariable analysis underscored the significance of TTR and various clinicopathological factors, encompassing age, tumor location, R0 resection status, differentiation grade, disease stage, postoperative chemoradiotherapy, and preoperative CEA levels, as substantial prognostic indicators. The postoperative survival nomogram, when internally and externally assessed, demonstrated commendable performance across multiple metrics, including the area under the receiver operating characteristic curve (AUC), calibration plots, and decision curve analysis (DCA). Compared with other models, the proportional hazards model combined with TTR demonstrates superior performance in terms of C-index, AUC, calibration chart, and DCA within the prognostic column chart.ConclusionsThe preoperative TTR was identified as a prognostic factor for predicting the long-term prognosis of CRC patients who underwent surgical treatment, supporting its role as a prognostic biomarker in clinical practice

    The clinical predictive value of geriatric nutritional risk index in elderly rectal cancer patients received surgical treatment after neoadjuvant therapy

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    ObjectiveThe assessment of nutritional status has been recognized as crucial in the treatment of geriatric cancer patients. The objective of this study is to determine the clinical predictive value of the geriatric nutritional risk index (GNRI) in predicting the short-term and long-term prognosis of elderly rectal cancer (RC) patients who undergo surgical treatment after neoadjuvant therapy.MethodsBetween January 2014 and December 2020, the clinical materials of 639 RC patients aged ≥70 years who underwent surgical treatment after neoadjuvant therapy were retrospectively analysed. Propensity score matching was performed to adjust for baseline potential confounders. Logistic regression analysis and competing risk analysis were conducted to evaluate the correlation between the GNRI and the risk of postoperative major complications and cumulative incidence of cancer-specific survival (CSS). Nomograms were then constructed for postoperative major complications and CSS. Additionally, 203 elderly RC patients were enrolled between January 2021 and December 2022 as an external validation cohort.ResultsMultivariate logistic regression analysis showed that GNRI [odds ratio = 1.903, 95% confidence intervals (CI): 1.120–3.233, p = 0.017] was an independent risk factor for postoperative major complications. In competing risk analysis, the GNRI was also identified as an independent prognostic factor for CSS (subdistribution hazard ratio = 3.90, 95% CI: 2.46–6.19, p < 0.001). The postoperative major complication nomogram showed excellent performance internally and externally in the area under the receiver operating characteristic curve (AUC), calibration plots and decision curve analysis (DCA). When compared with other models, the competing risk prognosis nomogram incorporating the GNRI achieved the highest outcomes in terms of the C-index, AUC, calibration plots, and DCA.ConclusionThe GNRI is a simple and effective tool for predicting the risk of postoperative major complications and the long-term prognosis of elderly RC patients who undergo surgical treatment after neoadjuvant therapy

    The oyster genome reveals stress adaptation and complexity of shell formation

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    The Pacific oyster Crassostrea gigas belongs to one of the most species-rich but genomically poorly explored phyla, the Mollusca. Here we report the sequencing and assembly of the oyster genome using short reads and a fosmid-pooling strategy, along with transcriptomes of development and stress response and the proteome of the shell. The oyster genome is highly polymorphic and rich in repetitive sequences, with some transposable elements still actively shaping variation. Transcriptome studies reveal an extensive set of genes responding to environmental stress. The expansion of genes coding for heat shock protein 70 and inhibitors of apoptosis is probably central to the oyster's adaptation to sessile life in the highly stressful intertidal zone. Our analyses also show that shell formation in molluscs is more complex than currently understood and involves extensive participation of cells and their exosomes. The oyster genome sequence fills a void in our understanding of the Lophotrochozoa. © 2012 Macmillan Publishers Limited. All rights reserved

    Coordination controlled electrodeposition and patterning of layers of palladium/copper nanoparticles on top of a self-assembled monolayer

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    Support by EPSRC (EP/E061303/1, EP/D048761/1) and the Chinese Scholarship Council and the University of St Andrews for a stipend (Z. Y.) are gratefully acknowledged.A scheme for the generation of bimetallic nanoparticles is presented which combines electrodeposition of one type of metal, coordinated to a self-assembled monolayer (SAM), with another metal deposited from the bulk electrolyte. In this way PdCu nanoparticles are generated by initial complexation of Pd2+ to a SAM of 3-(4-(pyridine-4-yl)phenyl)propane-1-thiol (PyP3) on Au/mica and subsequent reduction in an acidic aqueous CuSO4 electrolyte. Cyclic voltammetry reveals that the onset of Cu deposition is triggered by Pd reduction. Scanning tunneling microscopy (STM) shows that layers of connected particles are formed with an average thickness of less than 3 nm and lateral dimensions of particles in the range of 2 to 5 nm. In X-ray photoelectron spectra a range of binding energies for the Pd 3d signal is observed whereas the Cu 2p signal appears at a single binding energy, even though chemically different Cu species are present: normal and more noble Cu. Up to three components are seen in the N 1s signal, one originating from protonated pyridine moieties, the others reflecting the SAM-metal interaction. It is suggested that the coordination controlled electrodeposition yields layers of particles composed of a Pd core and a Cu shell with a transition region of a PdCu alloy. Deposited on top of the PyP3 SAM, the PdCu particles exhibit weak adhesion which is exploited for patterning by selective removal of particles employing scanning probe techniques. The potential for patterning down to the sub-10 nm scale is demonstrated. Harnessing the deposition contrast between native and PdCu loaded PyP3 SAMs, structures thus created can be developed into patterned continuous layers.PostprintPeer reviewe

    Generation of micro/nano metallic nanostructures using self-assembled monolayers as template and electrochemistry

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    This thesis studies a scheme to fabricate small-scaled metal structures by electrochemical metal deposition and lift off. The key point is the use of self-assembled monolayers (SAMs) to control both interfacial charge transfer in electrodeposition and adhesion of the deposit to the substrate. Patterned SAMs exhibiting blocking and non-blocking areas are applied as templates in electrochemical deposition of Cu or Au. Thiol SAMs on Au substrates are used, namely alkane thiols and thiols combining an aliphatic chain with a biphenyl or biphenyl analogous pyridine-phenyl moieties. The patterning of SAMs is realised with microcontact printing (μCP) and electron beam lithography. Electrochemical deposition based on defects in the SAMs is optimised towards generating small nanostructures and depending on the system single or stepped potential procedures are applied. Generated metal structures are transferred to an insulator by lift off. Au microstructures (~10 μm) have been made with microcontact printing and transferred onto epoxy glue, which can potentially be used as microelectrodes in electroanalytical chemistry. Sub-100 nm Cu features and sub-40 nm Au features have been created with electron beam lithography respectively. Lift off process has successfully transferred Cu nanostructures onto epoxy glue with high precision. In contrast to the deposition mediated by defects, Cu deposition mediated by discharging Pd²⁺ coordinated to a pyridine terminated SAM directly through the SAM molecules has been explored as a new approach. This new approach has potential to decrease the size of the metal structure further and the preliminary results show possibility of sub-10 nm features. SAMs prepared with a newly synthesised molecule, 3-(4'-(methylthio)-[1,1'-biphenyl]-4-yl)propane-1-thiol, are characterised by STM, XPS and NEXAFS. The metal structures are investigated by SEM, AFM and STM

    Analysis of hybrid wind-photovoltaic-hydro generation system based on short-term scheduling

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    Abstract Renewable energy sources are beneficial to provide clean power generation but simultaneously brings power supply risk due to natural uncertainties. A hybrid wind-solar-hydro generation system, which takes advantage of the complementary characteristic of renewable energy sources, is capable to supply the power demand reliably. A multi-objective model of the hybrid system is proposed to achieve minimum power supply risk and maximum economic benefit under natural limitations. To handle natural uncertainties, autoregressive integrated moving average model is applied to produce typical daily models of weather conditions in different scenarios. Meanwhile, particle swarm optimization algorithm is improved to solve the multi-objective model by introducing the ϵ-constraint method. Lastly, an example of a large-scale hybrid wind-photovoltaic-hydro system is given to analyse reliability, profit, efficiency and operation in different scenarios. The study has shown that the hybrid system does not crash reliability but increases economic benefit, it’s necessary to reserve wind and solar generation, wind generation needs to cooperate with hydro generation according to water dispatching.</jats:p
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