Characterisation of thermally treated beech and birch by means of quasi-static tests and ultrasonic waves.

Wood, being renewable and highly abundant material, with excellent high specific strength and stiffness, has received increasing attention to be used in high performance applications such as the structural element of a battery case in an electric vehicle. For a successful implementation of wood in the automotive sector, it is, therefore, crucial to understand the behaviour of wood during and after temperature exposure and in the event of fire with the presence/absence of oxygen. In this study, the mechanical properties of thermally modified and unmodified European beech and birch in air and nitrogen environments at six different treatment intensities were characterised using compression tests, tensile tests, shear tests and Poisson's ratio tests. Further, the elastic properties of these wood species were quantified using the ultrasound measurements. The obtained strength and stiffness exhibited mild improvement upon moderate temperature treatment (200 °C), followed by a decrease at elevated temperature levels. This improvement was somewhat more pronounced under nitrogen treatment than under air treatment conditions. Nevertheless, a more noticeable decrease in the material performance was observed in beech compared to birch, occurring at earlier stages of modifications. This study confirms the tension-compression asymmetry of beech and birch where higher Young's moduli were obtained from tensile than from compression tests for reference and thermally treated beech and birch. The shear moduli obtained from ultrasound for birch were comparable to those obtained from quasi-static tests, whereas there was an overestimation of approximately 11-59% for the shear modulus of beech compared to quasi-static tests. Poisson's ratios from ultrasound tests corresponded well with those from quasi-static tests for untreated beech and birch, but not for thermally modified samples. The Saint-Venant model can satisfactorily predict the shear moduli of untreated and treated beech wood.

A Comparative Study on the Temperature Effect of Solid Birch Wood and Solid Beech Wood under Impact Loading.

In order to use wood for structural and load-bearing purposes in mechanical engineering, basic information on the impact behaviour of the material over a wide temperature range is needed. Diffuse porous hardwoods such as solid birch wood (Betula pendula) and solid beech wood (Fagus sylvatica) are particularly suited for the production of engineered wood products (EWPs) such as laminated veneer lumber (LVL) or plywood due to their processability in a veneer peeling process. In the frame of this study, solid birch wood and solid beech wood samples (300 × 20 × 20 mm3) were characterised by means of an impact pendulum test setup (working capacity of 150 J) at five temperature levels, ranging from -30 °C to +90 °C. The pendulum hammer (mass = 15 kg) was equipped with an acceleration sensor in order to obtain the acceleration pulse and deceleration force besides the impact bending energy. In both solid birch wood and solid beech wood, the deceleration forces were highest at temperatures at and below zero. While the average impact bending energy for solid birch wood remained almost constant over the whole considered temperature range, it was far less stable and prone to higher scattering for solid beech wood.

Interfacial Adhesion and Mechanical Properties of Wood-Polymer Hybrid Composites Prepared by Injection Molding.

Birch (Betula pendula Roth.) and beech (Fagus sylvatica L.) solid wood and plywood were overmolded with polyamide 6 (PA 6) and polypropylene (PP) to investigate their mechanical properties and interfacial adhesion. In the case of PA 6, maximum tensile shear strengths values of more than 8 to 9 MPa were obtained for birch and beech, respectively. The values are comparable to bond strengths of commercial joints bonded with formaldehyde-containing amino-plastics. Perpendicular to the wood elements, bond strength values of 3 MPa was achieved for PA 6. The penetration of the polymers into the wood structure results in a non-densified interphase and subsequent plastic deformation of the wood structure beyond the interphase. These compressed areas influenced the interfacial adhesion and mechanical interlocking. SEM and XPS analysis revealed different interpenetration behavior of the polymers into the wood structure, with chemical interaction confirmed only for wood and PA 6 but not PP.

Placental growth factor levels neither reflect severity of portal hypertension nor portal-hypertensive gastropathy in patients with advanced chronic liver disease.

BACKGROUND & AIMS: Experimental data indicates that placental growth factor (PLGF) is involved in the pathophysiology of portal hypertension (PH) due to advanced chronic liver disease (ACLD). We investigated serum levels of PLGF and its "scavenger", the receptor soluble fms-like tyrosine kinase-1 (sFLT1, or sVEGFR1), in ACLD patients with different severity of PH and portal-hypertensive gastropathy (PHG). METHODS: PLGF and sVEGFR1 were measured in ACLD patients with hepatic venous pressure gradient (HVPG) ≥6 mmHg (n = 241) and endoscopic evaluation of PHG (n = 216). Patients with pre-/posthepatic PH, TIPS, liver transplantation and hepatocellular carcinoma were excluded. RESULTS: Thirty-two (13%) patients had HVPG 6-9 mmHg, 128 (53%) 10-19 mmHg and 81 (34%) ≥20 mmHg; 141 (59%) had decompensated ACLD (dACLD). PLGF (median 17.2 vs. 20.8 vs. 22.4 pg/mL; p = 0.002), sVEGFR1 (median 96.0 vs. 104.8 vs. 119.3 pg/mL; p < 0.001) levels increased across HVPG strata, while PLGF/sVEGFR1 ratios remained similar (0.19 vs. 0.20 vs. 0.18 pg/mL; p = 0.140). The correlation between PLGF and HVPG was weak (Rho = 0.190,95%CI 0.06-0.31; p = 0.003), and the PLGF/sVEGFR1 ratio did not correlate with HVPG (p = 0.331). The area-under-the-receiver operating characteristics (AUROC) for PLGF to detect clinically significant PH (CSPH;i.e. HVPG ≥ 10 mmHg) yielded only 0.688 (0.60-0.78; p < 0.001). When compared to ACLD patients without PHG, PLGF levels (20 without vs. 21.4 with mild vs. 17.1 pg/mL with severe PHG, respectively; p = 0.005) and PLGF/sVEGFR1 ratios (0.20 vs. 0.19 vs. 0.17; p = 0.076) did not increase with mild and severe PHG. CONCLUSION: While PLGF levels tended to increase with severity of PH, the PLGF/sVEGFR1 ratio remained stable across HVPG strata. Neither PLGF nor the PLGF/sVEGFR1 ratio had diagnostic value for prediction of CSPH. The severity of PHG was also not associated with stepwise increases in PLGF levels or PLGF/sVEGFR1 ratio.

Vitamin A levels reflect disease severity and portal hypertension in patients with cirrhosis.

BACKGROUND AND AIMS: The liver plays a key role in the storage, metabolism and homeostasis of fat-soluble vitamins. We investigated the relation of Vitamin(Vit)A/D/E serum levels with severity of liver disease and portal hypertension (PHT). METHODS: VitA/D/E serum levels were assessed in 234 patients with advanced chronic liver disease (ACLD, i.e. hepatic venous pressure gradient [HVPG] ≥ 6 mmHg). Patients with hepatocellular carcinoma, pre-/post-hepatic PHT, TIPS or liver transplantation were excluded. RESULTS: Most patients were male (n = 153; 65%) with a median age of 57.6 (49.7-64.5) years. Thirty-two (14%) patients had HVPG 6-9 mmHg, 66 (28%) 10-15 mmHg, and 136 (58%) ≥ 16 mmHg, respectively. VitD deficiency (25-OH-vitamin-D <50 nmol/L) was found in 133 (57%) with higher prevalence in Child-Turcotte-Pugh (CTP)-C: 85% vs. B: 66% vs. A: 47% (p < 0.001). VitD levels displayed significant but weak correlations with hepatic dysfunction and PHT. VitE levels were normal in 227 (97%) patients and displayed no relevant association with hepatic dysfunction or PHT. Only 63 (27%) patients had normal (>1.05 µmol/L) VitA levels, while 58 (25%) had mild (0.70-1.04 µmol/L), 71 (30%) moderate (0.35-0.69 µmol/L), and 42(18%) severe(<0.35 µmol/L) VitA deficiency. VitA correlated with HVPG (Rho = -0.409), CTP score (Rho = -0.646), and serum bile acid levels (Rho = -0.531; all p < 0.001). The prevalence of decompensated ACLD (dACLD) continuously increased with severity of VitA deficiency (no: 40% vs. mild: 51% vs. moderate: 67% vs. severe: 91% had dACLD; p < 0.001). CTP score (per point; OR 2.46; 95%CI 1.80-3.37; p <0.001), age (per year; OR 0.95; 95%CI 0.92-0.98; p = 0.001) and elevated bile acid levels(>10 µmol/L; OR 3.62; 95%CI 1.61-8.14; p = 0.002) were independently associated with VitA deficiency. CONCLUSION: VitA and VitD but not VitE deficiencies are highly prevalent in ACLD. VitA deficiency strongly correlates with hepatic dysfunction, PHT and bile acid levels and is associated with decompensated ACLD. TRIAL REGISTRATION NUMBER: NCT03267615.

Temperature-Related Properties of Solid Birch Wood under Quasi-Static and Dynamic Bending.

The project WoodC.A.R. investigates the capabilities of wood and engineered wood-products (EWPs) for their application as a load-bearing material in automotive applications. For crash-relevant components, materials have to provide a high impact bending energy over a wide range of climatic conditions. This study investigates the effect of temperature on the bending behavior of solid birch wood beams (800 × 90 × 43 mm3) under quasi-static and dynamic loading. Specimens were exposed to a three-point bending test with lateral confinement, replicating the hypothetical installation environment in a car, at five temperature levels: -30 °C, 0 °C, +30 °C, +60 °C, and +90 °C. A cylindrical impactor (D = 254 mm, m = 91 kg) was propelled against the center of the beam with an initial velocity of 8.89 m/s (dynamic) and at a constant velocity of 10 mm/min (quasi-static), respectively. Specimens were conditioned in a freezer and a climate chamber, respectively. Temperature was monitored prior and during testing. Bulk density and global fiber deviation were determined afterwards. In both, the dynamic and the quasi-static load case maximum force slightly decreased with increasing temperature, but remained almost constant at temperatures exceeding +30 °C. On average, the maximum dynamic peak force level was twice as high as in quasi-static tests. In the quasi-static tests, the energy absorption remained constant at elevated temperatures (+30 °C to +90 °C) but decreased by about 50% at lower temperatures -30 °C and 0 °C. In the dynamic tests, the energy absorption remained almost constant throughout the entire temperature range.

Thromboelastometry in patients with advanced chronic liver disease stratified by severity of portal hypertension.

BACKGROUND: Rotational thromboelastometry (ROTEM) has been studied in patients with advanced chronic liver disease (ACLD) without considering the impact of portal hypertension. We evaluated the influence of the hepatic venous pressure gradient (HVPG) on ROTEM results in patients with ACLD. METHODS: Cross-sectional study; ACLD patients undergoing HVPG measurement within the prospective Vienna Cirrhosis Study (NCT03267615) underwent concomitant ROTEM testing. RESULTS: Among 159 patients (68% male; Child-Pugh-A: 53%, Child-Pugh-B: 34%, Child-Pugh-C: 13%), 21 patients (13%) had a HVPG between 6 and 10 mmHg, 84 patients (53%) between 10 and 19 mmHg, and 54 patients (34%) ≥ 20 mmHg. Child-Pugh-C patients (vs. Child-Pugh-A and vs. Child-Pugh-B patients, respectively) showed longer clot formation time (CFT: median 187 s vs. 122 s vs. 122 s, p = 0.007) and lower maximum clot firmness (MCF: median: 45 mm vs. 56 mm vs. 56 mm, p = 0.002) in extrinsic thromboelastometry (EXTEM), while platelet counts were similar across Child-Pugh stages. In the overall cohort, ROTEM parameters did not differ by severity of portal hypertension. However, among compensated Child-Pugh-A patients, MCF decreased with increasing portal pressure, i.e. in higher HVPG strata (HVPG 9-10 mmHg: median MCF: 59 mm vs. HVPG 10-19 mmHg: 56 mm vs HVPG ≥ 20 mmHg: 54 mm, p = 0.023). Furthermore, patients with short CFT and high MCF in EXTEM had higher levels of lipopolysaccharide-binding protein, C-reactive protein, and procalcitonin, as well as higher leukocyte counts (all p < 0.05). CONCLUSIONS: Portal hypertension seems to impact ROTEM results only in compensated Child-Pugh-A patients. Bacterial translocation and systemic inflammation may trigger a procoagulant state in patients with ACLD.

Non-invasive detection of portal hypertension by enhanced liver fibrosis score in patients with different aetiologies of advanced chronic liver disease.

BACKGROUND AND AIMS: The enhanced liver fibrosis (ELF) score comprises serum markers of fibrogenesis and matrix remodelling and was developed to detect liver fibrosis, however, it may also be useful for the non-invasive detection of portal hypertension (PHT). METHODS: ELF score and its single components (TIMP1/PIIINP/HA) were analysed in 201 patients with advanced chronic liver disease (ACLD; ie hepatic venous pressure gradient (HVPG) ≥6 mm Hg). Patients with pre-/post-hepatic PHT, hepatocellular carcinoma beyond Milan criteria, and history of TIPS implantation or liver transplantation were excluded. RESULTS: ELF and its single components correlated with HVPG in the overall cohort: ELF: r = .443, TIMP1: r = .368, PIIINP:r = .332, and HA:r = .419 (all P < .001). The strength of the correlation between ELF and HVPG decreased in higher HVPG strata: 6-9 mm Hg:r = .569(P = .004), 10-19 mm Hg:r = .304 (P = .001) and ≥20 mm Hg:r = -.023(P = .853). Area under the receiver operating characteristics (AUROC) of ELF score to detect clinically significant PHT (CSPH; HVPG ≥ 10 mm Hg) was 0.833. Importantly, HA alone yielded an AUROC of 0.828. Detection of CSPH in strictly compensated ACLD (cACLD) patients was less accurate: AUROC: 0.759 (P < .001). CSPH was ruled-in by ELF ≥ 11.1 with a PPV of 98% (sensitivity: 61%/specificity: 92%/NPV:24%), but CSPH could not be ruled-out. ELF score had a low AUROC of 0.677 (0.60-0.75; P < .001) for the diagnosis of high-risk PHT (HRPH; HVPG ≥ 20mm Hg) and, thus, HRPH could not be ruled-in by ELF. However, ELF < 10.1 ruled-out HRPH with a NPV of 95% (sensitivity: 97%/specificity: 26%/PPV: 39%). CONCLUSION: The ELF score correlates with HVPG at values <20 mm Hg. An ELF ≥ 11.1 identifies patients with a high probability of CSPH, while an ELF < 10.1 may be used to rule-out HRPH.

Influence of Fiber Deviation on Strength of Thin Birch (Betula pendula Roth.) Veneers.

The currently pursued implementation of wood into novel high performance applications such as automotive parts require knowledge about the material behaviour including ultimate strength. Previous research has shown that fiber deviation seems to be the dominating factor influencing the strength of thin veneers. This study aims to further investigate and quantify the influence of fiber deviation in two dimension and different hierarchical levels on the tensile strength of thin birch veneers. The fiber deviation in- and out-of-plane as well as the micro fibril angle were assessed by means of wide-angle X-ray scattering. Tensile strength was determined in laboratory experiments. Results show a high variability for in-plane fiber deviation mainly constituted by knots and other growth influencing factors. Pearson correlations between strength and fiber deviation ranged from -0.594 up to -0.852. Best correlation (r = -0.852) was achieved for maximum in-plane fiber deviation directly followed by a combined angle of in- and out-of-plane fiber deviation (r = -0.846). Based on the results it was shown that fiber deviation in- and out-of-plane is the dominating factor influencing ultimate tensile strength of thin birch veneers. Further research in regard to non-destructive strength prediction is necessary.

ePTFE-TIPS vs repetitive LVP plus albumin for the treatment of refractory ascites in patients with cirrhosis.

BACKGROUND & AIMS: Reduction in portal pressure by self-expandable polytetrafluoroethylene (ePTFE)-covered transjugular intrahepatic portosystemic shunts (TIPS) is a treatment option for refractory ascites. Data on clinical outcomes after ePTFE-TIPS vs repetitive large-volume paracentesis (LVP) plus albumin (A) administration for the treatment of patients with refractory ascites are limited. METHODS: Retrospective comparison of ePTFE-TIPS vs LVP+A in terms of (i) control of ascites, (ii) occurrence of overt hepatic encephalopathy (HE) and (iii) transplant-free survival in cirrhotic patients with refractory ascites. RESULTS: Among n = 221 patients with cirrhosis and refractory ascites, n = 140 received ePTFE-TIPS and were compared to n = 71 patients undergoing repetitive LVP+A. After ePTFE-TIPS, ascites was controlled without any further need for paracentesis in n = 76 (54%; n = 7 without and n = 69 with diuretics). The need for frequent large-volume paracentesis was significantly higher in the LVP+A group than with ePTFE-TIPS (median 0.67 (IQR: 0.23-2.63) months vs 49.5 (IQR: 5.07-102.60) months until paracentesis, log-rank P < .001). De-novo incidence of HE was similar in ePTFE-TIPS and LVP+A patients (log-rank P = .361). Implantation of ePTFE-TIPS was associated with improved 1-year survival as compared to LVP+A (65.6% vs 48.4%, log-rank P = .033). Age (odds ratio (OR):1.05; 95% confidence interval (95% CI):1.03-1.07; P < .001), serum albumin (OR: 0.95; 95% CI: 0.92-0.99; P = .013) and hepatocellular carcinoma (OR: 1.66; 95% CI: 1.06-2.58; P = .026) emerged as independent predictors of survival. CONCLUSIONS: ePTFE-TIPS results in superior control of ascites without increasing the risk for overt HE as compared to LVP+A. Although ePTFE-TIPS improved 1-year survival in cirrhotic patients with refractory ascites, its use was not independently associated with transplant-free survival.

A multicenter prospective study on the diagnostic performance of a new liquid rapid urease test for the diagnosis of Helicobacter pylori infection.

BACKGROUND: Helicobacter pylori (H. pylori) causes a diversity of gastric diseases. Rapid urease tests (RUT) are well established for the point-of-care, invasive diagnosis of H. pylori infection. The study aimed to evaluate the diagnostic performance of a new liquid RUT, the preOx-HUT, within a prospective cohort of treatment-naïve patients. METHODS: The multicenter prospective clinical trial was conducted at nine Austrian centers for gastrointestinal endoscopy. Patients referred for a diagnostic upper gastrointestinal endoscopy underwent gastric biopsy sampling for routine histological evaluation, and in parallel, the preOx-HUT. Histology served as reference standard to evaluate the diagnostic performance of the preOx-HUT. RESULTS: From January 2015 to January 2016, a total of 183 consecutive patients (54 males and 129 females, median age 50 years) were included. Endoscopy revealed pathological findings in 149/183 cases (81%), which were mostly gastritis (59%) and gastro-esophageal reflux disease (27%). H. pylori infection was detected by histology in 41/183 (22%) cases. In relation to histology, the preOx-HUT had a sensitivity of 85%, a specificity of 94%, a positive predictive value of 80% and a negative predictive value of 96%. Performance of preOx-HUT was not affected significantly by concomitant PPI-use as present in 15% of cases (P = 0.73). CONCLUSIONS: This was the first study evaluating the preOx-HUT in a prospective, multicenter clinical setting. We found a high diagnostic accuracy for the point-of-care, invasive diagnostic test of H. pylori infection. Hence, this test may be a valuable diagnostic adjunct to the clinical presentation of patients with suspected H. pylori infection. Trial registration number EK 1548/2014, Name of registry: Register der Ethikkommission der Medizinischen Universität Wien, URL of registry: https://ekmeduniwien.at/core/catalog/2012/, Date of registration: 24.09.2014, Date of enrolment of the first participant to the trial: 15.01.2015.

The Human Gastric Microbiome Is Predicated upon Infection with Helicobacter pylori.

The human gastric lumen is one of the most hostile environments of the human body suspected to be sterile until the discovery of Helicobacter pylori (H.p.). State of the art next generation sequencing technologies multiply the knowledge on H.p. functional genomics as well as on the colonization of supposed sterile human environments like the gastric habitat. Here we studied in a prospective, multicenter, clinical trial the 16S rRNA gene amplicon based bacterial microbiome in a total of 30 homogenized and frozen gastric biopsy samples from eight geographic locations. The evaluation of the samples for H.p. infection status was done by histopathology and a specific PCR assay. CagA status was determined by a CagA-specific PCR assay. Patients were grouped accordingly as H.p.-negative, H.p.-positive but CagA-negative and H.p.-positive and CagA-positive (n = 10, respectively). Here we show that H.p. infection of the gastric habitat dominates the gastric microbiota in most patients and is associated with a significant decrease of the microbial alpha diversity from H.p. negative to H.p. positive with CagA as a considerable factor. The genera Actinomyces, Granulicatella, Veillonella, Fusobacterium, Neisseria, Helicobacter, Streptococcus, and Prevotella are significantly different between the H.p.-positive and H.p.-negative sample groups. Differences in microbiota found between CagA-positive and CagA-negative patients were not statistically significant and need to be re-evaluated in larger sample cohorts. In conclusion, H.p. infection dominates the gastric microbiome in a multicentre cohort of patients with varying diagnoses.