588 research outputs found
Soft Templating and Disorder in an Applied 1D Cobalt Coordination Polymer Electrocatalyst
Disordered materials with resilient and soft-templated functional units bear the
potential to fill the pipeline of robust catalysts for renewable energy storage.
However, for novel materials lacking long-range order, the ability to discern
local structure with atomic resolution still pushes the boundaries of current
analytical and modeling approaches. We introduce a two-pillar strategy to
monitor the formation and unravel the structure of the first disordered onedimensional cobalt coordination polymer catalyst, Co-dppeO2. This target
material excels through proven high performance in commercial alkaline
electrolyzers and organic transformations. We demonstrate that the key architecture behind this activity is the unconventional embedding of hydrated
{H2O-Co2(OH)2-OH2} edge-site motifs, nested into a flexible organic matrix of
highly oxidized and bridging hydrophobic dppeO2 ligands. Our combination
of in situ spectroscopy and computational modeling of X-ray scattering and
absorption spectra, backed with complementary experimental techniques,
holds the key to understanding the atomic-range structure of important
disordered materials
Scope and Mechanistic Study of the Coupling Reaction of α,ÎČ-Unsaturated Carbonyl Compounds with Alkenes: Uncovering Electronic Effects on Alkene Insertion vs Oxidative Coupling Pathways
The cationic ruthenium-hydride complex [(C6H6)(PCy3)(CO)RuH]+BF4â (1) was found to be a highly effective catalyst for the intermolecular conjugate addition of simple alkenes to α,ÎČ-unsaturated carbonyl compounds to give (Z)-selective tetrasubstituted olefin products. The analogous coupling reaction of cinnamides with electron-deficient olefins led to the oxidative coupling of two olefinic CâH bonds in forming (E)-selective diene products. The intramolecular version of the coupling reaction efficiently produced indene and bicyclic fulvene derivatives. The empirical rate law for the coupling reaction of ethyl cinnamate with propene was determined as follows: rate = k[1]1[propene]0[cinnamate]â1. A negligible deuterium kinetic isotope effect (kH/kD = 1.1 ± 0.1) was measured from both (E)-C6H5CHâC(CH3)CONHCH3 and (E)-C6H5CDâC(CH3)CONHCH3 with styrene. In contrast, a significant normal isotope effect (kH/kD = 1.7 ± 0.1) was observed from the reaction of (E)-C6H5CHâC(CH3)CONHCH3 with styrene and styrene-d8. A pronounced carbon isotope effect was measured from the coupling reaction of (E)-C6H5CHâCHCO2Et with propene (13C(recovered)/13C(virgin) at CÎČ = 1.019(6)), while a negligible carbon isotope effect (13C(recovered)/13C(virgin) at CÎČ = 0.999(4)) was obtained from the reaction of (E)-C6H5CHâC(CH3)CONHCH3 with styrene. Hammett plots from the correlation of para-substituted p-X-C6H4CHâCHCO2Et (X = OCH3, CH3, H, F, Cl, CO2Me, CF3) with propene and from the treatment of (E)-C6H5CHâCHCO2Et with a series of para-substituted styrenes p-Y-C6H4CHâCH2 (Y = OCH3, CH3, H, F, Cl, CF3) gave the positive slopes for both cases (Ï = +1.1 ± 0.1 and +1.5 ± 0.1, respectively). Eyring analysis of the coupling reaction led to the thermodynamic parameters, ÎH⧧ = 20 ± 2 kcal molâ1 and ÎS⧧ = â42 ± 5 eu. Two separate mechanistic pathways for the coupling reaction have been proposed on the basis of these kinetic and spectroscopic studies
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No straight lines â young womenâs perceptions of their mental health and wellbeing during and after pregnancy: a systematic review and meta-ethnography
Background: Young mothers face mental health challenges during and after pregnancy including increased rates of depression compared to older mothers. While the prevention of teenage pregnancy in countries such as the United States and the United Kingdom has been a focus for policy and research in recent decades, the need to understand young womenâs own experiences has been highlighted. The aim of this meta-ethnography was to examine young womenâs perceptions of their mental health and wellbeing during and after pregnancy to provide new understandings of those experiences.
Methods: A systematic review and meta-ethnographic synthesis of qualitative research was conducted. Seven databases were systematically searched and forward and backward searching conducted. Papers were included if they were from Organisation for Economic Co-operation and Development countries and explored mental health and wellbeing experiences of young mothers (age under 20 in pregnancy; under 25 at time of research) as a primary research question â or where evidence about mental health and wellbeing from participants was foregrounded. Nineteen papers were identified and the Critical Appraisal Skills Programme checklist for qualitative research used to appraise the evidence. Following the seven-step process of meta-ethnography, key constructs were examined within each study and then translated into one another.
Results: Seven translated themes were identified forming a new line of argument wherein mental health and wellbeing was analysed as relating to individual bodily experiences; tied into past and present relationships; underpinned by economic insecurity and entangled with feelings of societal surveillance. There were âno straight linesâ in young womenâs experiences, which were more complex than dominant narratives around overcoming adversity suggest.
Conclusions: The synthesis concludes that health and social care professionals need to reflect on the operation of power and stigma in young womenâs lives and its impact on wellbeing. It adds to understanding of young womenâs mental health and wellbeing during and after pregnancy as located in physical and structural factors rather than individual capacities alone
An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core
Silver nanoparticles have antibacterial properties, but their use has been a cause for concern because they persist in the environment. Here, we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green alternative to silver nanoparticles. The polyelectrolyte layer promotes the adhesion of the particles to bacterial cell membranes and, together with silver ions, can kill a broad spectrum of bacteria, including Escherichia coli, Pseudomonas aeruginosa and quaternary-amine-resistant Ralstonia sp. Ion depletion studies have shown that the bioactivity of these nanoparticles is time-limited because of the desorption of silver ions. High-throughput bioactivity screening did not reveal increased toxicity of the particles when compared to an equivalent mass of metallic silver nanoparticles or silver nitrate solution. Our results demonstrate that the application of green chemistry principles may allow the synthesis of nanoparticles with biodegradable cores that have higher antimicrobial activity and smaller environmental impact than metallic silver nanoparticles
WNT signalling in prostate cancer
Genome sequencing and gene expression analyses of prostate tumours have highlighted the potential importance of genetic and epigenetic changes observed in WNT signalling pathway components in prostate tumours-particularly in the development of castration-resistant prostate cancer. WNT signalling is also important in the prostate tumour microenvironment, in which WNT proteins secreted by the tumour stroma promote resistance to therapy, and in prostate cancer stem or progenitor cells, in which WNT-ÎČ-catenin signals promote self-renewal or expansion. Preclinical studies have demonstrated the potential of inhibitors that target WNT receptor complexes at the cell membrane or that block the interaction of ÎČ-catenin with lymphoid enhancer-binding factor 1 and the androgen receptor, in preventing prostate cancer progression. Some WNT signalling inhibitors are in phase I trials, but they have yet to be tested in patients with prostate cancer
Macroporous polymer supported azide and nanocopper (I): efficient and reusable reagent and catalyst for multicomponent click synthesis of 1,4-disubstituted-1H-1,2,3-triazoles from benzyl halides
Techno-Ecological Synergy: A Framework for Sustainable Engineering
Even though the importance of ecosystems in sustaining all human activities is well-known, methods for sustainable engineering fail to fully account for this role of nature. Most methods account for the demand for ecosystem services, but almost none account for the supply. Incomplete accounting of the very foundation of human well-being can result in perverse outcomes from decisions meant to enhance sustainability and lost opportunities for benefiting from the ability of nature to satisfy human needs in an economically and environmentally superior manner. This paper develops a framework for understanding and designing synergies between technological and ecological systems to encourage greater harmony between human activities and nature. This framework considers technological systems ranging from individual processes to supply chains and life cycles, along with corresponding ecological systems at multiple spatial scales ranging from local to global. The demand for specific ecosystem services is determined from information about emissions and resource use, while the supply is obtained from information about the capacity of relevant ecosystems. Metrics calculate the sustainability of individual ecosystem services at multiple spatial scales and help define necessary but not sufficient conditions for local and global sustainability. Efforts to reduce ecological overshoot encourage enhancement of life cycle efficiency, development of industrial symbiosis, innovative designs and policies, and ecological restoration, thus combining the best features of many existing methods. Opportunities for theoretical and applied research to make this framework practical are also discussed
MicroRNA profiling of cisplatinresistant oral squamous cell carcinoma cell lines enriched withcancer-stem-cell-like and epithelial-mesenchymal transition-type features
Oral cancer is of major public health problem in India. Current investigation was aimed to identify
the specific deregulated miRNAs which are responsible for development of resistance phenotype
through regulating their resistance related target gene expression in oral squamous cell carcinoma
(OSCC). Cisplatin-resistant OSCC cell lines were developed from their parental human OSCC cell lines
and subsequently characterised. The resistant cells exhibited enhanced proliferative, clonogenic
capacity with significant up-regulation of P-glycoprotein (ABCB1), c-Myc, survivin, ÎČ-catenin and a
putative cancer-stem-like signature with increased expression of CD44, whereas the loss of E-cadherin
signifies induced EMT phenotype. A comparative analysis of miRNA expression profiling in parental
and cisplatin-resistant OSCC cell lines for a selected sets (deregulated miRNAs in head and neck cancer)
revealed resistance specific signature. Moreover, we observed similar expression pattern for these
resistance specific signature miRNAs in neoadjuvant chemotherapy treated and recurrent tumours
compared to those with newly diagnosed primary tumours in patients with OSCC. All these results
revealed that these miRNAs play an important role in the development of cisplatin-resistance mainly
through modulating cancer stem-cell-like and EMT-type properties in OSCC
Combined changes in Wnt signalling response and contact inhibition induce altered proliferation in radiation treated intestinal crypts
Curative intervention is possible if colorectal cancer is identified early, underscoring the need to detect the earliest stages of malignant transformation. A candidate biomarker is the expanded proliferative zone observed in crypts before adenoma formation, also found in irradiated crypts. However, the underlying driving mechanism for this is not known. Wnt signaling is a key regulator of proliferation, and elevated Wnt signaling is implicated in cancer. Nonetheless, how cells differentiate Wnt signals of varying strengths is not understood. We use computational modeling to compare alternative hypotheses about how Wnt signaling and contact inhibition affect proliferation. Direct comparison of simulations with published experimental data revealed that the model that best reproduces proliferation patterns in normal crypts stipulates that proliferative fate and cell cycle duration are set by the Wnt stimulus experienced at birth. The model also showed that the broadened proliferation zone induced by tumorigenic radiation can be attributed to cells responding to lower Wnt concentrations and dividing at smaller volumes. Application of the model to data from irradiated crypts after an extended recovery period permitted deductions about the extent of the initial insult. Application of computational modeling to experimental data revealed how mechanisms that control cell dynamics are altered at the earliest stages of carcinogenesis
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