Wallenberg Wood Science Center

Sparse representation systems that encode signal structure have had a profound impact on sampling and compression paradigms. Remarkable examples are multi-scale directional systems, which, similar to our vision system, encode the underlying structure of natural images with sparse features. Inspired by this philosophy, we introduce a representation system for wave-based acoustic signal processing in 2D space–time, which has one spatial and one temporal dimension. We refer to this representation as the boostlet transform , which encodes sparse features of natural acoustic fields using the Poincaré group and isotropic dilations. Boostlets are spatiotemporal functions parametrized with dilations, Lorentz boosts, and translations in space–time. Physically speaking, boostlets are wave functions propagating with phase speeds other than the speed of sound, resulting in a peculiar scaling function. We formulate a discrete boostlet transform using a tensor product of Meyer wavelets and bump functions. An analysis with experimentally measured fields indicates that discrete boostlet coefficients decay significantly faster and attain superior reconstruction performance than wavelets, curvelets, shearlets, and wave atoms. The results suggest that boostlets offer a natural and compact representation of broadband acoustic waves in space–time.

We determine the composition dependence of the below-bandgap anisotropic refractive indices and dielectric functions of β-(AlxGa1−x)2O3 for x up to 25% Al. We use Mueller matrix generalized spectroscopic ellipsometry and investigate a set of high quality single crystalline bulk (x=0%,5%,10%,15%,20%,25%) and thin film (4.6%, 9.7%, 12%, 15%, 16.3%, 21%) samples grown by the Czochralski method and by plasma-assisted molecular beam epitaxy, respectively. Bulk samples with 0.2% silicon doping are cut from ingots with (100) surface and the unintentionally doped thin films samples are grown pseudomorphically on (010) β-Ga2O3. The combination of ellipsometry data from both sample sets permits to fully determine the optical properties of the transparent alloys. We employ a quasi-orthorhombic approach which ignores the very small shear components induced by the monoclinic crystal structure. We also ignore the possibly small effects due to strain within the pseudomorphically grown epitaxial samples. We report indices and dielectric functions for polarization along lattice vectors a, b, and reciprocal lattice vector c⋆. All indices reduce with increasing incorporation of aluminum while the spectral range of transparency increases due to the increase in bandgap energy with composition. We use our results to predict Bragg reflector multilayer structures on b-plane β-(Al0.20Ga0.80)2O3, for use in polarization sensitive narrow-band optical filters in the short wavelength region.

• Peracetic acid produces aspen holocellulose fibers preserving hemicellulose in 5 h. • Short aspen fibers match spruce strength in high-density holocellulose networks. • Critical fiber length explains fiber dimension insignificance in dense networks. • High interfiber shear strength causes fiber fractures, not pull-out at failure. • Holocellulose networks offer potential for recyclability with minimal fiber degradation. Mechanical behavior of high-density oriented spruce and aspen fiber networks from mildly delignified holocellulose fibers is investigated. Such recyclable, eco-friendly fiber networks are of interest for molded fiber materials and biocomposites. The aspen holocellulose fiber network showed excellent mechanical properties comparable to spruce despite much shorter fiber length. This contrasts with lower density “paper” structures from short fibers which show lower strength than spruce fiber networks. Present results are explained by improved interfiber shear strength and reduced critical fiber length. Microstructures and damage mechanisms were analyzed for materials design purposes using FE-SEM, wide-angle X-ray scattering (WAXS) and tensile testing with strain-field measurements using Digital Image Correlation (DIC).

BackgroundGlobal longitudinal strain (GLS) and left atrial strain metrics, including reservoir (LAr), contraction (LAct), and conduit strain (LAcd), have emerged as key indicators of left ventricular (LV) function and filling pressures. However, the prognostic value of these markers for risk stratification in acute heart failure (HF) remains uncertain, particularly in identifying patients at elevated risk of rehospitalization and mortality.ResultsIn the prospective HARVEST cohort study, LA strain and GLS measurements were obtained retrospectively in 141 patients (mean age 71 ± 13, 25% women). Strain values are reported as absolute values reflecting the magnitude of deformation regardless of sign. Multivariable adjusted Cox regression was used to test whether GLS, LAr, LAct, and LAcd were associated with all-cause mortality and HF rehospitalization. Hazard ratios were calculated per 1% decrease in strain values. During a median follow-up time of 39 (IQR 14–66) months (490 patient-years) for mortality analyses and 22 (IQR 4–51) months (354 patient-years) for HF rehospitalization 62 (44%) patients died, and 62 (44%) were rehospitalized. Higher GLS, LAr, and LAcd were associated with a lower risk of mortality (HR:0.94, 95%CI:0.89–0.99, p = 0.045; HR:0.93, 95%CI:0.89–0.98, p = 0.009; and HR:0.94, 95%CI:0.88–0.99, p = 0.039, respectively), and higher LAr and LAct were associated with reduced risk of HF rehospitalization (HR:0.93, 95%CI:0.88–0.98, p = 0.004; and HR:0.85, 95%CI:0.77–0.94, p = 0.002, respectively).ConclusionIn patients with acute HF, strain parameters predict prognosis, with poorer outcomes. Notably, decreasing LAr was associated with increased risk of both death and rehospitalization for HF, whereas decreasing GLS was only associated with higher mortality risk.Supplementary InformationThe online version contains supplementary material available at 10.1186/s44156-026-00106-6.

Abstract For siRNA drugs to be relevant in tumors, poor endosomal escape of these drugs needs to be addressed. Endosomal escape can occur when the endolysosomal membrane is damaged and can be visualized by endogenously expressed fluorescent galectin-9 functioning as damage sensors. Tumor cells have unstable membranes and central parts of tumors have low nutrient levels contributing to reactive oxygen species which can induce membrane damage. We show that nutrient depletion alone does not induce endolysosomal membrane damage in HeLa and MCF7 cells or in HeLa spheroids. Serum depletion, however, enhanced endolysosomal membrane damage in HeLa cells when combined with the membrane destabilizing drug chloroquine, a cationic amphiphilic drug. This effect was almost completely abolished when depleting the cells of glucose, even when serum was present. This phenomenon could not be seen with other cationic amphiphilic drugs like siramesine and loperamide. In a functional experiment, co-treatment with chloroquine and siGFP significantly improved knockdown of GFP in the presence but not in the absence of glucose. Our results have implications for the development of chloroquine as an endosomal escape enhancer of RNA therapeutics in tumor contexts and stresses the importance of considering nutrient levels and tumor size in future screenings.

Enlargement of the choroidal-ventricular system occurs in aging and Alzheimer's disease (AD), but emerging evidence links these abnormalities to amyloid beta (Aβ) aggregation. We tested this hypothesis by assessing associations between AD pathophysiology and choroidal-ventricular system measures across the AD continuum. Ventricular volume, choroid-plexus volume, and ventricular radioactivity after positron emission tomography (PET) tracer injections were analyzed in 385 Translational Biomarkers in Aging and Dementia (TRIAD) and 282 Alzheimer's Disease Neuroimaging Initiative (ADNI) participants using linear models and partial correlations. A composite score combining these measures was also tested against established AD biomarkers. With advancing AD stages, ventricular and choroid-plexus volumes increased while ventricular radioactivity declined. These measures were interrelated, and abnormalities appeared even in amyloid-negative elderly. Across cohorts, they correlated with amyloid- and tau-PET, cerebrospinal fluid (CSF) and plasma p-tau isoforms, glial fibrillary acidic protein (GFAP), and cognition. Voxel-wise analyses showed strong associations with cortical Aβ, mediating downstream tau effects. Changes in the choroidal-ventricular system are mutually correlated and carry an additive-effect on cortical Aβ load.

Abstract The term nanocellulose includes a group of cellulose-based nanofibers that have attracted great attention within the research community. To date, many different types of nanocelluloses are known with a range of dimensions and surface functionalities affecting the properties of the material and which applications they can be used for. One type of nanocellulose can be made through simultaneous esterification and hydrolysis of cellulose with oxalic acid. The reaction of cellulose with oxalic acid results in a cellulose ester (cellulose oxalate), that has a carboxylic acid attached through an ester bond. In this study, the stability of the cellulose oxalate ester towards base-catalysed hydrolysis was investigated through immersion in buffer solutions with pH ranging from 6 to 10. The results show that the ester is rapidly hydrolysed already within 24 h at pH above 8. It could also be concluded that the carboxylic acid functionality of the cellulose oxalate is relatively acidic (pKa of 3.8) and that for carboxylic group content determination through conductometric titration, the equivalence point and not the plateau should be used. The results from this study show that stability of the ester needs to be carefully considered when working with cellulose oxalate.

Lignin-carbohydrate complexes, in which lignin and polysaccharides are directly connected, have been identified and extensively analyzed. To date, however, the origin of these structures has not been unequivocally established. That notwithstanding, it has been found that delignification, whether by conventional pulping and bleaching processes or in the biorefinery context, is effected by the presence of lignin-carbohydrate complexes. Using density functional theory calculations, the current work has evaluated the thermodynamics of bond dissociation as a function of structure and chemical composition. Among the lignin-carbohydrate complexes that have been identified, the homolytic bond dissociation energy is highest for the α-benzyl ethers and γ-ester, with phenyl glycosides being markedly less endothermic. This is consistent with observations on the recalcitrance of these compounds. Heterolytic cleavage reactions of the α-benzyl ethers are less endothermic, due to water solvation of the ions. The latter observation may provide support for the proposed homolytic cleavage reaction, since if heterolysis were operative, the α-benzyl ethers would not exhibit the level of recalcitrance that is observed experimentally.