Poly(acrylic acid) interpolymer complexation: use of a fluorescence time resolved anisotropy as a poly(acrylamide) probe

YesA low concentration poly(acrylamide) sensor has been developed which uses the segmental mobility of another polymer probe with a covalently attached fluorescent marker. Interpolymer complexation with poly(acrylic acid) leads to reduced segmental mobility which can be used to determine the concentration of polymer in solution. This technique could be useful in detecting the runoff of polymer dispersants and flocculants in fresh water supplies following water purification processes.Funding for the research was kindly provided by the Engineering and Physical Sciences Research Council (EPSRC)

pH Responsive Highly Branched Poly(N-isopropylacrylamide) with Trihistidine or Acid Chain Ends

YesThermally responsive highly branched poly(N-isopropyl acrylamide)s (HB-PNIPAM) were prepared and end-functionalised to give polymers with acid or trihistidine end groups. These polymers exhibit a broad coil-to-globule transition across a wide temperature range which can be measured using covalently attached fluorescent tags. The acid chain ends provided a material with a distinct change in solution behaviour at pH close to the pKa of the carboxylate group. At pH 11 this polymer did not show a cloud point up to 50 °C but fluorescence measurements on the labelled polymers showed that a coil to glubule transition did take place. The globular state, above the LCST, appeared to be more swollen if the end group carried charge then when it was uncharged. A polymer with trihistidine and free carboxylate chain ends, which contained multiple charges at various pH, did show LCSTs at all pH and the polymer globule was shown to be swollen at each pH

Effect of increased inspired oxygen on exercise performance in patients with heart failure and normal ejection fraction

Introduction: We investigated whether increased concentrations of inspired oxygen (FiO2) affects exercise tolerance in patients with heart failure and normal ejection fraction (HeFNEF). Methods: 46 patients (mean age 75 years (63% male) and median NTproBNP 1432 (interquartile range: 543–2378 ng/l)) with HeFNEF (defined as signs or symptoms of heart failure requiring treatment with diuretics, with a left ventricular ejection fraction of >45% by echocardiography and amino terminal pro brain natriuretic peptide (NTproBNP) >220 ng/l) completed three maximal incremental exercise tests with different FiO2 (21%, 28% and 40%) in random order. FiO2 was controlled by investigator but blinded to patients. The primary outcome was exercise time (ET). Results: Increasing FiO2 significantly increased exercise time (522 ± 180 seconds for 21% to 543 ± 176 seconds, and 542 ± 177 seconds, for 28% and 40%, respectively, P = 0.04) with no difference in peak workload (57 ± 25 W, 58 ± 25 W and 57 ± 25 W, for 21%, 28% and 40%, respectively, P = 0.50). There was an increase in oxygen saturation but no change in peak heart rate with increasing FiO2. Compared to patients with LVEF ≥50%, patients with LVEF between 45 and 49% had a significantly greater exercise time and peak workload. There was a correlation between the difference in exercise time between FiO2 21% and 40% and age; but not with BMI, haemoglobin, creatinine or NTproBNP. Conclusion: Increasing FiO2 during exertion leads to a small increase in exercise time in patients with HeFNEF

Brain-derived neurotrophic factor association with amygdala response in major depressive disorder

Background: Brain-derived neurotrophic factor (BDNF) has an essential role in synaptic plasticity and neurogenesis. BDNF mediates amygdala-dependent learning for both aversive and appetitive emotional memories. The expression of BDNF in limbic regions is posited to contribute the development of depression, and amygdala responsivity is a potential marker of depressive state. Methods: The present study examined the relationship between platelet BDNF levels and amygdala volume and function in major depressive disorder (MDD). Participants were 23 MDD (mean age 38.9 years) and 23 healthy controls (mean age 38.8 years). All participants were recruited from the community. MDD participants were in a current depressive episode of moderate severity and medication-free. Amygdala responses were acquired during a functional MRI task of implicit emotional processing with sad facial expressions. Results: Significant correlation was observed between platelet BDNF levels and left amygdala responses, but no significant correlations were found with right amygdala responses or with amygdala volumes. Limitations: Interactions with neuroprotective as well as neurotoxic metabolites in the kyneurenine pathway were not examined. Conclusions: Relationship between BDNF levels and amygdala responsivity to emotionally salient stimuli in MDD could reflect the importance of BDNF in amygdala-dependent learning with clinical implications for potential pathways for treatment

A spectral survey of an ultra-hot Jupiter: Detection of metals in the transmission spectrum of KELT-9 b

Context: KELT-9 b exemplifies a newly emerging class of short-period gaseous exoplanets that tend to orbit hot, early type stars - termed ultra-hot Jupiters. The severe stellar irradiation heats their atmospheres to temperatures of $\sim 4,000$ K, similar to the photospheres of dwarf stars. Due to the absence of aerosols and complex molecular chemistry at such temperatures, these planets offer the potential of detailed chemical characterisation through transit and day-side spectroscopy. Studies of their chemical inventories may provide crucial constraints on their formation process and evolution history. Aims: To search the optical transmission spectrum of KELT-9 b for absorption lines by metals using the cross-correlation technique. Methods: We analyse 2 transits observed with the HARPS-N spectrograph. We use an isothermal equilibrium chemistry model to predict the transmission spectrum for each of the neutral and singly-ionized atoms with atomic numbers between 3 and 78. Of these, we identify the elements that are expected to have spectral lines in the visible wavelength range and use those as cross-correlation templates. Results: We detect absorption of Na I, Cr II, Sc II and Y II, and confirm previous detections of Mg I, Fe I, Fe II and Ti II. In addition, we find evidence of Ca I, Cr I, Co I, and Sr II that will require further observations to verify. The detected absorption lines are significantly deeper than model predictions, suggesting that material is transported to higher altitudes where the density is enhanced compared to a hydrostatic profile. There appears to be no significant blue-shift of the absorption spectrum due to a net day-to-night side wind. In particular, the strong Fe II feature is shifted by $0.18 \pm 0.27$ km~s$^{-1}$, consistent with zero. Using the orbital velocity of the planet we revise the steller and planetary masses and radii.Comment: Submitted to Astronomy and Astrophysics on January 18, 2019. Accepted on May 3, 2019. 26 pages, 11 figure