754 research outputs found
Probing the interactions of phenol with oxygenated functional groups on curved fullerene-like sheets in activated carbon
The mechanism(s) of interactions of phenol with oxygenated functional groups (OH, COO and COOH) in nanopores of activated carbon (AC) is a contentious issue among researchers. This mechanism is of particular interest because a better understanding of the role of such groups in nanopores would essentially translate to advances in AC production and use, especially in regard to the treatment of organic-based wastewaters. We therefore attempt to shed more light on the subject by employing density functional theory (DFT) calculations in which fullerene-like models integrating convex or concave structure, which simulate the eclectic porous structures on AC surface, are adopted. TEM analysis, EDS mapping and Boehm titration are also conducted on actual phenol-adsorbed AC. Our results suggest the widely-reported phenomenon of decreased phenol uptake on AC due to increased concentration of oxygenated functional groups is possibly attributed to the increased presence of the latter on the convex side of the curved carbon sheets. Such a system effectively inhibits phenol from getting direct contact with the carbon sheet, thus constraining any available π–π interaction, while the effect of groups acting on the concave part of the curved sheet does not impart the same detriment
Endotaxial Stabilization of 2D Charge Density Waves with Long-range Order
Charge density waves are emergent quantum states that spontaneously reduce
crystal symmetry, drive metal-insulator transitions, and precede
superconductivity. In low-dimensions, distinct quantum states arise, however,
thermal fluctuations and external disorder destroy long-range order. Here we
stabilize ordered two-dimensional (2D) charge density waves through endotaxial
synthesis of confined monolayers of 1T-TaS. Specifically, an ordered
incommensurate charge density wave (oIC-CDW) is realized in 2D with
dramatically enhanced amplitude and resistivity. By enhancing CDW order, the
hexatic nature of charge density waves becomes observable. Upon heating via
in-situ TEM, the CDW continuously melts in a reversible hexatic process wherein
topological defects form in the charge density wave. From these results, new
regimes of the CDW phase diagram for 1T-TaS are derived and consistent with
the predicted emergence of vestigial quantum order
Magnetic anisotropy reversal driven by structural symmetry-breaking in monolayer {\alpha}-RuCl3
Layered {\alpha}-RuCl3 is a promising material to potentially realize the
long-sought Kitaev quantum spin liquid with fractionalized excitations. While
evidence of this exotic state has been reported under a modest in-plane
magnetic field, such behavior is largely inconsistent with theoretical
expectations of Kitaev phases emerging only in out-of-plane fields. These
predicted field-induced states have been mostly out of reach due to the strong
easy-plane anisotropy of bulk crystals, however. We use a combination of
tunneling spectroscopy, magnetotransport, electron diffraction, and ab initio
calculations to study the layer-dependent magnons, anisotropy, structure, and
exchange coupling in atomically thin samples. Due to structural distortions,
the sign of the average off-diagonal exchange changes in monolayer
{\alpha}-RuCl3, leading to a reversal of magnetic anisotropy to easy-axis. Our
work provides a new avenue to tune the magnetic interactions in {\alpha}-RuCl3
and allows theoretically predicted quantum spin liquid phases for out-of-plane
fields to be more experimentally accessible
Inhibition of cytokine-mediated JNK signalling by purinergic P2Y11 receptors, a novel protective mechanism in endothelial cells
Previous research from our laboratory has demonstrated a novel phenomenon whereby GPCRs play a role in inhibiting cytokine-mediated c-Jun N-terminal kinase (JNK) signalling. So far this novel phenomenon seems to have been vastly overlooked, with little research in the area. Therefore, in this study we explored this further; by assessing the potential of P2YRs to mediate inhibition of cytokine-mediated JNK signalling and related functional outcomes in human endothelial cells. We utilised primary endothelial cells, and employed the use of endogenous activators of P2YRs and well characterised pharmacological inhibitors, to assess signalling parameters mediated by P2YRs, Interleukin-1β (IL-1β), TNFα and JNK. Activation of P2YRs with adenosine tri-phosphate (ATP) resulted in a time- and concentration-dependent inhibition of IL-1β-mediated phosphorylation of JNK and associated kinase activity. The effect was specific for cytokine-mediated JNK signalling, as ATP was without effect on JNK induced by other non-specific activators (e.g. sorbitol, anisomycin), nor effective against other MAPK pathways such as p38 and the canonical NFκB cascade. Pharmacological studies demonstrated a role for the P2Y11 receptor in mediating this effect, but not the P2Y1 nor the adenosine receptors (A1, A2A, A2B & A3). The novel Gαq/11 inhibitor YM254890 and a protein kinase A (PKA) inhibitor H89 both partially reversed ATP-mediated inhibition of IL-1β-stimulated JNK indicating involvement of both Gαq/11 and Gαs mediated pathways. ATP also partially reversed IL-1β-mediated induction of cyclo‑oxygenase-2 (COX-2) and E-selectin. Collectively, these studies indicate the potential for activation of purinergic receptors to protect the endothelium from inflammatory driven JNK activation and may be a new target for inflammatory disease therapy
Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial
Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie
Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries
Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
Differential host utilisation by different life history stages of the fish ectoparasite Argulus foliaceus (Crustacea: Branchiura)
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Development, prevalence and treatment of blood pressure abnormalities in spinal cord injury
© 2019 Min Yin GohDisorders of blood pressure control arise from disruption of the autonomic nervous system and result in symptomatic orthostatic hypotension and large fluctuations in blood pressure. Ambulatory blood pressure monitoring is used in the general population for assessment of blood pressure control and to detect episodes of hypotension.
In spinal cord injury (SCI), impaired control of the sympathetic nervous system leads to orthostatic intolerance and autonomic dysreflexia. Smaller studies in restricted populations have examined ambulatory pressures in SCI and observed abnormalities in diurnal blood pressure variation in complete cervical SCI. Altered diurnal blood pressure is associated with abnormalities in diurnal urine production and orthostatic intolerance in autonomic failure. This triad may also occur in SCI to explain the orthostatic intolerance.
A retrospective examination of ambulatory pressures of patients with SCI referred for clinically significant blood pressure disorders revealed a high prevalence of abnormalities in diurnal blood pressure and urine production in acute and chronic tetraplegia and in acute paraplegia.
To characterise the course of diurnal blood pressure, urine production and orthostatic symptoms in SCI, two prospective studies were performed. First, consecutive patients admitted with acute SCI were screened for recruitment, and consenting volunteers were compared with immobilised and mobilising controls. In the second study, people with chronic SCI (>1 year) living in the community were compared with mobilising controls.
Compared with mobilising and immobilised controls, there was a high prevalence of abnormal diurnal blood pressure variation in SCI. The abnormalities were most prevalent and marked in higher and earlier SCI. Abnormalities persisted over time in both complete and incomplete cervical SCI. Abnormalities in high paraplegia were no different to that of cervical SCI in early SCI, but were no different to that of controls in chronic SCI. Nocturnal hypertension occurred in the absence of day hypertension in SCI, thus clinic pressures may miss elevation in blood pressures and ambulatory monitoring may be beneficial in assessment of blood pressure in SCI.
Abnormalities in diurnal urine production were present and persisted over time in cervical SCI, but appeared to improve over time with thoracic SCI, mirroring changes in diurnal blood pressure. Orthostatic hypotension and orthostatic intolerance were more prevalent in SCI than in controls. Mild orthostatic intolerance is common in chronic SCI and a small proportion had more severe symptoms. A single centre study to investigate a drug treatment for orthostatic intolerance in the setting of a loss of diurnal blood pressure variation was unsuccessful due to low recruitment rates.
As life expectancy increases in the SCI population, there is evidence of increased rates of cardiovascular disease. Similar to the general population, the loss of diurnal blood pressure variation and elevated nocturnal pressures may be a contributor to the increased cardiovascular disease in SCI, and thus a potential therapeutic target. Ambulatory blood pressure monitoring may be useful to detect these changes and examination of a larger SCI population with a longer duration of follow up for cardiovascular disease may help to determine this
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