Effect of Steam Treatment on the Properties of Wood Cell Walls

Steam treatment is a hygrothermal method of potential industrial significance for improving the dimensional stability and durability of wood materials. The steaming results in different chemical and micromechanical changes in the nanostructured biocomposite that comprise a wood cell wall. In this study, spruce wood (Picea abies Karst.) that had been subjected to high-temperature steaming up to 180 °C was examined, using imaging Fourier Transform Infrared (FT-IR) microscopy and nanoindentation to track changes in the chemical structure and the micromechanical properties of the secondary cell wall. Similar changes in the chemical components, due to the steam treatment, were found in earlywood and latewood. A progressive degradation of the carbonyl groups in the glucuronic acid unit of xylan and a loss of mannose units in the glucomannan backbone, that is, a degradation of glucomannan, together with a loss of the CO group linked to the aromatic skeleton in lignin, was found. The development of the hygroscopic and micromechanical properties that occurred with an elevation in the steam temperature correlated well with this pattern of degradation in the constituents in the biocomposite matrix in the cell wall (hemicellulose and lignin)

Water as an Intrinsic Structural Element in Cellulose Fibril Aggregates

While strong water association with cellulose in plant cell walls and man-made materials is well-established, its molecular scale aspects are not fully understood. The thermodynamic consequences of having water molecules located at the microfibril–microfibril interfaces in cellulose fibril aggregates are therefore analyzed by molecular dynamics simulations. We find that a thin layer of water molecules at those interfaces can be in a state of thermal equilibrium with water surrounding the fibril aggregates because such an arrangement lowers the free energy of the total system. The main reason is enthalpic: water at the microfibril–microfibril interfaces enables the cellulose surface hydroxyls to experience a more favorable electrostatic environment. This enthalpic gain overcomes the entropic penalty from strong immobilization of water molecules. Hence, those particular water molecules stabilize the cellulose fibril aggregates, akin to the role of water in some proteins. Structural and functional hypotheses related to this finding are presented

The utility of coagulation activity for prediction of risk of mortality and cardiovascular events in guideline-treated myocardial infarction patients

<p><b>Background:</b> Despite improved treatment of myocardial infarction (MI), real-world patients still suffer substantial risk for subsequent cardiovascular events. Little is known about coagulation activity shortly after MI and whether coagulation activity markers may identify patients at increased risk despite contemporary treatment.</p> <p><b>Objective:</b> To evaluate D-dimer concentration and thrombin generation potential shortly after discharge after MI and evaluate if these markers could predict the risk of future cardiovascular and bleeding events.</p> <p><b>Methods:</b> Unselected MI patients (<i>n</i> = 421) were included in the observational REBUS study (NCT01102933) and followed for two years. D-dimer concentrations, thrombin peak, and endogenous thrombin potential (ETP) were analyzed at inclusion (3–5 days after MI) and at early follow-up (after 2–3 weeks).</p> <p><b>Results:</b> Seventy-five patients (17.8%) experienced the composite endpoint (all-cause death, MI, congestive heart failure, or all-cause stroke), and 31 patients (7.4%) experienced a clinically relevant bleeding event. D-dimer concentrations at early follow-up were associated with the composite endpoint (HR [per SD increase] 1.51 [95% CI 1.22–1.87]) and with clinically relevant bleeding (HR [per SD increase] 1.80 [95% CI 1.32–2.44]). Thrombin generation potential was not significantly associated with either the composite endpoint or with clinically relevant bleeding. Higher thrombin peak and ETP at early follow-up were both inversely associated with stroke (HR [per SD increase] 0.50 [95% CI 0.30–0.81] and 0.43 [95% CI 0.22–0.83], respectively).</p> <p><b>Conclusion:</b> In unselected MI patients treated according to contemporary guidelines, D-dimer measurements may identify patients at increased risk of new cardiovascular and bleeding events. The inverse association of thrombin generation potential and risk of stroke has to be further investigated.</p

Low-Birefringent and Highly Tough Nanocellulose-Reinforced Cellulose Triacetate

Improvement of the mechanical and thermal properties of cellulose triacetate (CTA) films is required without sacrificing their optical properties. Here, poly­(ethylene glycol) (PEG)-grafted cellulose nanofibril/CTA nanocomposite films were fabricated by casting and drying methods. The cellulose nanofibrils were prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and amine-terminated PEG chains were grafted onto the surfaces of the TEMPO-oxidized cellulose nanofibrils (TOCNs) by ionic bonds. Because of the nanosize effect of TOCNs with a uniform width of ∼3 nm, the PEG–TOCN/CTA nanocomposite films had high transparency and low birefringence. The grafted PEG chains enhanced the filler–matrix interactions and crystallization of matrix CTA molecules, resulting in the Young’s modulus and toughness of CTA film being significantly improved by PEG-grafted TOCN addition. The coefficient of thermal expansion of the original CTA film was mostly preserved even with the addition of PEG-grafted TOCNs. These results suggest that PEG–TOCNs are applicable to the reinforcement for transparent optical films

Deoxyguanosine Phosphate Mediated Sacrificial Bonds Promote Synergistic Mechanical Properties in Nacre-Mimetic Nanocomposites

We show that functionalizing polymer-coated colloidal nanoplatelets with guanosine groups allows synergistic increase of mechanical properties in nacre-mimetic lamellar self-assemblies. Anionic montmorillonite (MTM) was first coated using cationic poly­(diallyldimethylammonium chloride) (PDADMAC) to prepare core–shell colloidal platelets, and subsequently the remaining chloride counterions allowed exchange to functional anionic 2′-deoxyguanosine 5′-monophosphate (dGMP) counterions, containing hydrogen bonding donors and acceptors. The compositions were studied using elemental analysis, scanning and transmission electron microscopy, wide-angle X-ray scattering, and tensile testing. The lamellar spacing between the clays increases from 1.85 to 2.14 nm upon addition of the dGMP. Adding dGMP increases the elastic modulus, tensile strength, and strain 33.0%, 40.9%, and 5.6%, respectively, to 13.5 GPa, 67 MPa, and 1.24%, at 50% relative humidity. This leads to an improved toughness seen as a ca. 50% increase of the work-to-failure. This is noteworthy, as previously it has been observed that connecting the core–shell nanoclay platelets covalently or ionically leads to increase of the stiffness but to reduced strain. We suggest that the dynamic supramolecular bonds allow slippage and sacrificial bonds between the self-assembling nanoplatelets, thus promoting toughness, still providing dynamic interactions between the platelets

Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance

Optically transparent wood (TW) with transmittance as high as 85% and haze of 71% was obtained using a delignified nanoporous wood template. The template was prepared by removing the light-absorbing lignin component, creating nanoporosity in the wood cell wall. Transparent wood was prepared by successful impregnation of lumen and the nanoscale cellulose fiber network in the cell wall with refractive-index-matched prepolymerized methyl methacrylate (MMA). During the process, the hierarchical wood structure was preserved. Optical properties of TW are tunable by changing the cellulose volume fraction. The synergy between wood and PMMA was observed for mechanical properties. Lightweight and strong transparent wood is a potential candidate for lightweight low-cost, light-transmitting buildings and transparent solar cell windows

Relations between GDF-15 levels and cardiovascular and cancer outcomes.

<p>GDF-15 (ng/l) in relation to logit of risk for total mortality, cardiovascular disease (CVD) mortality, coronary heart disease (CHD) morbidity/mortality, stroke morbidity/mortality, CVD mortality or CHD or stroke morbidity/mortality combined, and cancer mortality.</p

GDF-15 and other biomarkers in relation to cardiovascular and cancer outcomes.

<p>Adjusted hazard ratios with 95% CI for 1 SD increase of log transformed GDF-15 values and of log transformed values of other biomarkers in relation to 10 years outcome of total mortality, cardiovascular disease (CVD) mortality, CVD mortality or coronary heart disease (CHD) or stroke morbidity/mortality, cancer mortality and cancer morbidity/mortality, in the whole sample (n = 940), subjects without cardiovascular disease (non CVD sample, n = 561) and subjects without cancer disease (non cancer sample, n = 882) at baseline (outcome cancer morbidity/mortality only in the non-cancer sample). Hazard ratios are adjusted for age, current smoking, body mass index, systolic blood pressure, antihypertensive treatment, total cholesterol, HDL cholesterol, lipid-lowering treatment, type 2 diabetes, and cancer at baseline (except in population P3), and log transformed values of the biomarkers GDF‑15, NT-proBNP, troponin T, cystatin C, and CRP. </p

Intraclass correlation coefficients (ICC) for serum 25-hydroxyvitamin D levels between twins in a pair with 95% confidence intervals.

<p>The p-values correspond to a test of equality of the observed correlations.</p

Linear regression analyses for the relationship between the absolute differences85 in serum values between the methods against the mean of the two values.

<p>*Adjusted for twin-ship dependence.</p