The association of nutritional factors and skin autofluorescence in persons receiving hemodialysis

Objective: Advanced glycation end-products (AGEs) are uremic toxins that result from hyperglycemia, oxidative stress and systemic inflammation. AGEs are also formed in food during cooking. On the other hand, malnutrition may contribute to AGE formation through its association with oxidative stress and inflammation. AGE accumulation can be measured by skin autofluorescence (SAF) and elevated SAF is independently associated with higher mortality on hemodialysis (HD). We aimed to investigate associations between SAF, dietary AGE intake and markers of malnutrition in persons receiving HD.Design and setting: single center cross-sectional study.Subjects: 120 participants on HD dialyzing at least three times per week for 3-4 hours.Main outcome measures: SAF was measured using an Autofluorescence Reader. Dietary AGE, energy, protein and fat intake, handgrip strength (HGS), anthropometric measurements and biochemistry were also assessed. Subjective Global Assessment was performed to evaluate nutritional status.Results: SAF was higher in malnourished participants and correlated negatively with serum albumin and cholesterol, HGS and energy, protein and fat intake and positively with C reactive protein and chronological age; SAF did not correlate with dietary AGE intake. Multivariable linear regression analysis showed that diabetes, smoking, serum albumin, HGS, protein intake and dialysis vintage were independent predictors of increased SAF.Conclusions: Markers of malnutrition were more important determinants of increased SAF than high dietary AGE intake in this HD population. Nutritional interventions aiming to reduce SAF by correcting malnutrition should therefore be investigated. The observed association between higher SAF and malnutrition may in part explain the previously reported association between higher SAF and mortality on HD

Detection of nanoplastic by surface-enhanced Raman microscopy

Currently the extent of nanoplastic in the environment can only be estimated by extrapolation from the plastic waste that can be detected. To be able to quantify the whole extent of the problem, detection methods have to be developed that can also identify particles that are smaller than 1 $\mu$m. Here we employ surface-enhanced Raman scattering (SERS) to image and identify single nanoplastic particles down to 100 nm in size. We obtain an experimental enhancement factor of more than three orders of magnitude measured on a single plastic particle instead of averaging over a concentration. Our results contribute to the better understanding and employment of SERS for nanoparticle detection and present an important step for the development of future sensors.Comment: 9 pages, 7 figure

Factors associated with change in skin autofluorescence in persons receiving dialysis

IntroductionAn increase over time in skin autofluorescence (SAF), a measure of accumulation of advanced glycation end products (AGE), predicts higher mortality on hemodialysis (HD). However, evidence is lacking regarding factors that contribute to changes in SAF over time in populations on dialysis. We investigated the rate of change in SAF over 1 year and the factors associated with these changes.MethodsWe enrolled 109 patients on HD and 28 on peritoneal dialysis in a prospective study. SAF was measured at baseline, 3, 6, 9, and 12 months. Rate of change in SAF was calculated using the SLOPE function in Microsoft Excel (Microsoft, Redmond, WA). Participants were then grouped into those with stable SAF or increasing SAF. Dietary AGE intake and nutritional assessments were performed at baseline, 6, and 12 months.ResultsThe mean SAF trend observed was an increase of 0.30 ± 0.63 arbitrary units (AU) per year, but this varied from a decrease of 0.15 ± 0.44 to an increase of 0.76 ± 0.42 AU per year in stable and increasing SAF groups, respectively. Increasing SAF was more common in participants who developed malnutrition during the observation period, whereas those who became well-nourished were more likely to have stable SAF (8 [80%] vs. 14 [42%]; P = 0.02). Development/prevalence of malnutrition over 1 year, HD as first dialysis modality, and current smoking were independent predictors of increasing SAF.ConclusionSAF increases over time in most persons on dialysis. Independent determinants of increasing SAF were development/prevalence of malnutrition, HD as first dialysis modality, and current smoking. Strategies to reduce/prevent the rise in SAF, including prevention/correction of malnutrition, should be investigated in prospective studies

Nonreciprocal transmission of magnetoacoustic waves in compensated synthetic antiferromagnets

We investigate the interaction between surface acoustic waves (SAWs) and spin waves (SWs) in a Pt/Co(2nm)/Ru(0.85nm)/Co(2nm)/Pt compensated synthetic antiferromagnet (SAF) composed of two ferromagnetic layers with equal thicknesses separated by a thin nonmagnetic Ru spacer layer. Because of the combined presence of interlayer dipolar coupling fields and interfacial Dzyaloshinskii–Moriya interaction (iDMI), the optical SW mode shows a large nondegenerate dispersion relation for counter-propagating SWs. Due to resonant SAW-SW interaction, we observe a nonreciprocal SAW transmission in the prepared piezoelectric/SAF hybrid device. We demonstrate that the nonreciprocity of the SAW transmission in symmetric SAFs with equal thicknesses of the magnetic layers can show a substantially different characteristic behavior in comparison to asymmetric SAFs or magnetic single layers with iDMI. For the prepared SAF, the nonreciprocal shift of the magnetoacoustic resonance fields and the magnetoacoustic SW excitation efficiency depend on the external magnetic field sweep direction. For one magnetic field sweep direction and angle of the magnetic field, the resonance fields of the waves propagating in one direction are larger than for the waves propagating in the opposite direction. In addition, the magnitude of the nonreciprocal field shift is at minimum if the external magnetic field is aligned perpendicular to the SW propagation direction. The experimental results are in agreement with a phenomenological SAW-SW interaction model

Nonreciprocal magnetoacoustic waves in synthetic antiferromagnets with Dzyaloshinskii-Moriya interaction

The interaction between surface acoustic waves (SAWs) and spin waves (SWs) in a piezoelectric/magnetic thin film heterostructure yields potential for the realization of novel microwave devices and applications in magnonics. In the present work, we investigate the SAW-SW interaction in a Pt/Co(2nm)/Ru(0.85nm)/Co(4nm)/Pt synthetic antiferromagnet (SAF) composed of two ferromagnetic layers with different thicknesses separated by a thin nonmagnetic Ru spacer layer. Because of the combined presence of interfacial Dzyaloshinskii–Moriya interaction (iDMI) and interlayer dipolar coupling fields, the optical SW mode shows a large nondegenerate dispersion relation for oppositely propagating SWs. Due to SAW-SW interaction, we observe nonreciprocal SAW transmission in the piezoelectric/SAF hybrid device. The equilibrium magnetization directions of both Co layers are manipulated by an external magnetic field to set a ferromagnetic, canted, or antiferromagnetic configuration. This has a strong impact on the SW dispersion, its nonreciprocity, and SAW-SW interaction. The experimental results are in agreement with a phenomenological SAW-SW interaction model, which considers the interlayer exchange coupling, iDMI, and interlayer dipolar coupling fields of the SWs

Observation of Nonspreading Wave Packets in an Imaginary Potential

We propose and experimentally demonstrate a method to prepare a nonspreading atomic wave packet. Our technique relies on a spatially modulated absorption constantly chiseling away from an initially broad de Broglie wave. The resulting contraction is balanced by dispersion due to Heisenberg's uncertainty principle. This quantum evolution results in the formation of a nonspreading wave packet of Gaussian form with a spatially quadratic phase. Experimentally, we confirm these predictions by observing the evolution of the momentum distribution. Moreover, by employing interferometric techniques, we measure the predicted quadratic phase across the wave packet. Nonspreading wave packets of this kind also exist in two space dimensions and we can control their amplitude and phase using optical elements.Comment: 4 figure