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Selective catalytic oxidation of hydrogen in the presence of hydrocarbons was studied in a fixed bed quartz reactor, over 3 wt%Au/TiO2 and 5 wt%Au/TiO2 catalysts. This reaction can be utilised in the production of light alkenes via catalytic dehydrogenation, providing in situ heat to the endothermic dehydrogenation reaction and simultaneously removing a fraction of the produced hydrogen. It is important to avoid the non-selective combustion of the hydrocarbons in the mixture. Both 3 wt%Au/TiO2 and 5 wt%Au/TiO2 are active for the combustion of hydrogen, but in a gas mixture with propane and oxygen the selectivity is dependent upon the feed ratio of hydrogen and oxygen. At 550 °C, with propane present, no carbon oxides are formed when the H2:O2 ratio is four, but at lower ratios some CO2 and some CO is formed. [ABSTRACT FROM AUTHOR]

We report the OH stretching vibrational spectra of size-selected H[sup+](H[sub2]O)[subn] clusters through the region of the pronounced "magic number" at n = 21 in the cluster distribution. Sharp features are observed in the spectra and assigned to excitation of the dangling OH groups throughout the size range 6 ≤ n ≤ 27. A multiplet of such bands appears at small cluster sizes. This pattern simplifies to a doublet at n = 11, with the doublet persisting up to n = 20, but then collapsing to a single line in the n = 21 and n = 22 clusters and reemerging at n = 23. This spectral simplification provides direct evidence that, for the magic number cluster, all the dangling OH groups arise from water molecules in similar binding sites. [ABSTRACT FROM AUTHOR]

The effects of static and pulsed electric fields on the multiphoton ionization (MPI) of rubidium atoms at both low (atomic beam) and high (heat pipe) densities are studied using tunable OPO lasers. Two-photon excitation of rip states is induced by the external electric field at both low and high densities. In addition, rip signal is also seen at very low electric fields in the heat pipe, providing evidence for collision mixing as well as field mixing. At low Rb densities strong resonance features are observed in the energy region between the zero field limit (IP) and the field ionization limit. In addition, collisional detachment and charge transfer between excited ns and rid Rb Rydberg states and nozzle-jet cooled polar molecules (acetonitrile and acetone) are studied under crossed-beam conditions. The formation of dipole bound anions for acetone is only seen under nozzle jet expansion conditions and the maximum in the Rydberg electron transfer (RET) rate versus ii depends upon the expansion gas (nmax increases in the order H2, H2, He, Ar, Xe). For acetone (low dipole moment and large nmax), collisional detachment dominates the charge transfer, whereas for acetonitrile (high dipole moment and low nmax), charge transfer is seen to dominate the creation of Rb+. [ABSTRACT FROM AUTHOR]

Both the plantaris tendon and the peroneus tertius tendon are used as auto- and allogenous graft materials to reconstruct the ankle ligament complex. However, it is unclear to what extent these graft materials resemble the load-deformation behavior of the ankle ligaments. A total of 34 human ankle ligaments and 35 tendons were assessed mechanically deploying a quasi-static tensile testing setup. Tendons were significantly stiffer (median elastic moduli: plantaris tendon = 465.7 MPa, peroneus tertius tendon = 338.5 MPa, medial ligament = 61.4 MPa, lateral ligament = 49.3 MPa; p ≤ 0.035), but more distensible (median strain at maximum force: plantaris tendon = 15.1%, peroneus tertius tendon = 15.3%, medial ligament = 9.3%, lateral ligament = 9.6%; p ≤ 0.008) and mechanically tougher (median ultimate tensile strength: plantaris tendon = 51.0 MPa, peroneus tertius tendon = 40.5 MPa, medial ligament = 4.1 MPa, lateral ligament = 3.5 MPa; p ≤ 0.033) when compared to medial and lateral ankle ligaments. The lateral ligaments of the right ankle were significantly tougher compared to the left side (p = 0.015). The elastic modulus of the medial ligament (r = 0.489, p = 0.045) and the peroneus tertius tendon (r = 0.517, p = 0.014) yielded an age-dependent increase. Both tendons seem biomechanically suitable graft materials to replace the medial and lateral ankle ligaments during physiological loading. The age-dependent increase in tissue elastic properties of the medial vs. lateral ankle ligaments, and differences in ultimate tensile strength between the lateral ligaments left vs. right, may reflect the complex asymmetric loading behavior of both ankle ligaments. [ABSTRACT FROM AUTHOR]

The temporal muscle fascia (TMF) is a widely used graft material and of interest for computational simulations of the temporomandibular joint as well as computational and physical human head models in general. However, reliable biomechanical properties of the TMF are lacking to date. This study provides tensile data of 52 TMFs at an age range of 18 to 94 years. It further investigates, if acellular fascia scaffolds differ from native counterparts in their biomechanical behaviour. Native TMF has a median elastic modulus of 26.2 MPa (acellular: 24.5 MPa), an ultimate tensile strength of 2.9 MPa (acellular: 2.1 MPa), a maximum force of 12.6 N (acellular: 9.9 N) and a strain at failure of 14.1% (acellular: 14.8%). No significant difference was found regarding the properties of native and acellular samples. Elastic modulus and the ultimate tensile strength increased with age but only in the acellular group (p < 0.01). Decorin and fibronectin seemed to be washed out by the acellularization procedure. The absence of cells in acellular TMF samples is not of biomechanical relevance compared to the native state. Acellular TMF is a biomechanically promising scaffold material for graft purposes, which can be retrieved easily due to its superficial location. [ABSTRACT FROM AUTHOR]

AbstractCdSe quantum dots functionalized with oligo-(phenylene vinylene) (OPV) ligands (CdSe-OPV nanostructures) represent a new class of composite nanomaterials with significantly modified photophysics relative to bulk blends or isolated components. Single-molecule spectroscopy on these species have revealed novel photophysics such as enhanced energy transfer, spectral stability, and strongly modified excited state lifetimes and blinking statistics. Here, we review the role of ligands in quantum dot applications and summarize some of our recent efforts probing energy and charge transfer in hybrid CdSe-OPV composite nanostructures.

Sacroiliac joint dysfunction (SIJD) is an underappreciated source of back pain. Mineralization patterns of the sacroiliac (SIJ) subchondral bone plate (SCB) may reflect long-term adaptations to the loading of the joint. Mineralization densitograms of 27 SIJD patients and 39 controls, were obtained using CT osteoabsorptiometry. Hounsfield unit (HU) values of the SCB mineralization of superior, anterior and inferior regions on the iliac and sacral auricular surfaces were derived and statistically compared between SIJD-affected and control cohorts. Healthy controls showed higher HU values in the iliac; 868 ± 211 (superior), 825 ± 121 (anterior), 509 ± 114 (inferior), than in the sacral side; 541 ± 136 (superior), 618 ± 159 (anterior), 447 ± 91 (inferior), of all regions (p < 0.01). This was similar in SIJD; ilium 908 ± 170 (superior), 799 ± 166 (anterior), 560 ± 135 (inferior), sacrum 518 ± 150 (superior), 667 ± 151 (anterior), 524 ± 94 (inferior). In SIJD, no significant HU differences were found when comparing inferior sacral and iliac regions. Furthermore, HU values in the inferior sacral region were significantly higher when compared to the same region of the healthy controls (524 ± 94 vs. 447 ± 91, p < 0.01). Region mineralization correlated negatively with age (p < 0.01). SIJD-affected joints reflect a high mineralization of the sacral inferior region, suggesting increased SIJD-related mechanical stresses. Age-related SCB demineralization is present in all individuals, regardless of dysfunction. [ABSTRACT FROM AUTHOR]

Current treatments of plantar fasciitis are based on the premise that the Achilles tendon (AT) and plantar fascia (PF) are mechanically directly linked, which is an area of debate. The aim of this study was to assess the morphological relationship between the AT and PF. Nineteen cadaveric feet were x-ray imaged, serially sectioned and plastinated for digital image analyses. Measurements of the AT and PF thicknesses and cross-sectional areas (CSA) were performed at their calcaneal insertion. The fiber continuity was histologically assessed in representative subsamples. Strong correlations exist between the CSA of the AT and PF at calcaneal insertion and the CSA of PF's insertional length (r = 0.80), and between the CSAs of AT's and PF's insertional lengths. Further correlations were observed between AT and PF thicknesses (r = 0.62). This close morphological relationship could, however, not be confirmed through x-ray nor complete fiber continuity in histology. This study provides evidence for a morphometric relationship between the AT and PF, which suggests the presence of a functional relationship between these two structures following the biological key idea that the structure determines the function. The observed morphological correlations substantiate the existing mechanical link between the AT and PF via the posterior calcaneus and might explain why calf stretches are a successful treatment option for plantar heel pain. [ABSTRACT FROM AUTHOR]

Purpose: To describe the origin of the vessels supplying the anterior sub-axial cervical vertebrae (C3–C7) to further understand their potential influence on anterior bone loss after anterior cervical spinal surgery. Method: Cadaveric dissection was performed on ten adult human necks after latex perfusion of their subclavian, common carotid and vertebral arteries. The nutrient vessels of the sub-axial cervical spine were identified and traced to their origin. The course and distribution of these vessels and their nutrient foraminae are described. Results: In all cases the anterior nutrient vessels were derived from the thyro-cervical trunk with branches that passed over the longus coli muscles forming a leash of vessels in the pre-vertebral fascia which subsequently extended in a frond-like pattern to pass onto the anterior aspect of vertebrae. The more cranial the cervical level the fewer the number of nutrient vessels and foraminae. The distribution of the foraminae on the anterior vertebral body followed the oblique supero-medial course of the nutrient vessels. Conclusion: Nutrient vessels perforate the cervical vertebrae on their anterior surface. These are derived from a leash of vessels that lie within the pre-vertebral fascia overlying the longus coli muscles. The origin of these vessels is the ascending cervical artery with a variable contribution from the transverse cervical artery. [ABSTRACT FROM AUTHOR]

Obtaining biomechanical properties of biological tissues for simulation purposes or graft developments is time and resource consuming. The number of samples required for biomechanical tests could be reduced if the load-deformation properties of a given tissue layer could be estimated from adjacent layers or if the biomechanical parameters were unaffected by age, bodyside, sex or post-mortem interval. This study investigates for the first time potential correlations of multiple super-imposed tissue layers using the temporal region of the human head as an area of broad interest in biomechanical modelling. Spearman correlations between biomechanical properties of the scalp, muscle fascia, muscle, bone and dura mater from up to 83 chemically unfixed cadavers were investigated. The association with age, sex and post-mortem interval was assessed. The results revealed sporadic correlations between the corresponding layers, such as the maximum force (r = 0.43) and ultimate tensile strength (r = 0.33) between scalp and muscle. Side- and age-dependence of the biomechanical properties were different between the tissue types. Strain at maximum force of fascia (r = -0.37) and elastic modulus of temporal muscle (r = 0.26) weakly correlated with post-mortem interval. Only strain at maximum force of scalp differed significantly between sexes. Uniaxial biomechanical properties of individual head tissue layers can thus not be estimated solely based on adjacent layers. Therefore, correlations between the tissues' biomechanical properties, anthropometric data and post-mortem interval need to be established independently for each layer. Sex seems not to be a relevant influencing factor for the passive tissue mechanics of the here investigated temporal head tissue layers. [ABSTRACT FROM AUTHOR]

The passive load-deformation properties of the human temporal muscle applicable to computer simulations of the human head or the comparison of the temporal muscle to other graft materials are unexplored to date and it is unclear, if these properties depend on age, sex, post-mortem interval or body side. Eighty-eight fresh temporal muscle samples from 69 human cadavers (age range 4 months – 94 years) were investigated in a quasi-static tensile setup. For comparative reasons, 20 age-matched human temporal muscle fascia and scalp samples were tested in the same manner as the temporal muscle. Human temporal muscle showed an elastic modulus of 1.58 ± 0.64 MPa, an ultimate tensile strength of 0.26 ± 0.11 MPa and a strain at maximum force of 26.21 ± 12.48%. These parameters were independent of sex (p > 0.88), side (p > 0.92) and post-mortem interval (p > 0.09). All passive load-deformation parameters of the human temporal muscle differed from temporal muscle fascia and scalp except for the strain at maximum force of the temporal muscle and scalp. Significantly different load-deformation properties of the human temporal muscle from temporal muscle fascia and scalp indicate the need for a separate simulation of these soft tissue layers in computational head models to reflect lifelike conditions. Contrary to other tissues such as scalp or temporal muscle fascia the biomechanical temporal muscle properties in head models may not require adjustments for sex, side and age based on the here-presented findings. [ABSTRACT FROM AUTHOR]

The sacroiliac joint (SIJ) exhibits significant variation in auricular surface morphology. This variation influences the mechanics of the SIJ, a central node for transmitting mechanical energy from upper body to lower limbs and vice versa. The impact of the auricular surface morphology on stress and deformation in the SIJ remains poorly understood to date. Computed tomography scans obtained from 281 individuals were included to extract the geometry of the pelvic ring. Then, the auricular surface area, SIJ cartilage thickness, and total SIJ cartilage volume were identified. Based on these reconstructions, 281 finite element models were created to simulate SIJ mechanical loading. It was found that SIJ cartilage thickness only weakly depended on age or laterality, while being strongly sex sensitive. Auricular surface area and SIJ cartilage volume depended weakly and non-linearly on age, peaking around menopause in females, but without significant laterality effect. Larger SIJs, characterized by greater auricular area and cartilage volume, exhibited reduced stress and deformation under loading. These findings highlight the significant role of SIJ morphology in its biomechanical response, suggesting a potential link between morphological variations and the risk of SIJ dysfunction. Understanding this relationship could improve diagnosis and targeted treatment strategies for SIJ-related conditions., (© 2024 The Author(s). Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.)

Background: Surgical treatments of benign primary bone tumors of the femur face the challenge of limiting tissue damage and contamination while providing sufficient stabilization to avoid fracture. While no clear treatment guidelines exist, surgical treatment commonly consists of femoral fenestration and curettage with optional filling and plating of the defect. Mono- or bicortical plating of distal femoral defects aim to reduce fracture risk and have been shown to increase axial stability. However, it remains unclear whether plating increases torsional stability of the affected femur., Questions/purposes: This biomechanical study aimed to determine how much additional stability can be achieved by mono- or bicortical plating of femoral defects after fenestration. The following hypotheses were investigated: 1. Preventive plating of distal femur bone defects enhances torsional stability when compared to femoral fenestration alone. 2. A condition close to the intact (nonpathological) bone can be achieved by bone plating. 3. Defect shape influences torsional stability., Patients and Methods: Thiel embalmed human femora (n = 24) were left intact or subjected to the following surgical treatments (A) defect creation via fenestration, (B) defect with short monocortical plating, (C) defect with long bicortical plating. All femora were torsion tested in midstance position using pre-cycling and testing until failure. Quantitative computed tomography pre and post testing allowed bone mineral density calculation and crack path analysis. Finite element analysis provided insight into defect shape variations., Results: Torsion experiments showed no relevant enhancement of torsional stability due to mono- or bicortical plating. There were no significant differences in maximum torque between unplated and plated femora with defect (defect: 35.38 ± 7.53 Nm, monocortical plating: 37.77 ± 9.82 Nm, bicortical plating: 50.27 ± 9.72 Nm, p > 0.05). Maximum torque for all treatment groups was significantly lower compared to intact femora (155-200 Nm, p < 0.001). Cracks originated predominantly from the proximal posterior corner of the defect and intersected with screw holes in plated femora. The influence of variations of the defect corner shapes had no significant influence on maximum torque and angle., Conclusion: This biomechanical study shows that mono- or bicortical plating is not an effective preventive treatment against torsional failure of femora with distal defects as the resulting maximum torque was drastically reduced compared to intact femora. Thus, the initial hypotheses have to be rejected. As habitual loading of the femur includes a combination of axial and torsional loading, the observed lack of prevention against torsional failure might help to explain the occurrence of fractures despite plating. Future research towards ameliorating clinical outcome should address the role of defect filling with bone cement or bone grafts regarding the improvement of torsional stability after primary bone tumor treatment in the femur., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Andreas Leithner: Institutional educational grants by Johnson & Johnson, Medacta, Alphamed, Implantec., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

High energy pelvic injuries sustain significant mortality rates, due to acute exsanguination and severe associated injuries. Managing the hemodynamically unstable trauma patient with a bleeding pelvic fracture still forms a major challenge in acute trauma care. Various approaches have been applied through the last decades. At present the concept of Damage Control Resuscitation (DCR) is universally accepted and applied in major trauma centers internationally. DCR combines hemostatic blood transfusions to restore blood volume and physiologic stability, reduced crystalloid fluid administration, permissive hypotension, and immediate hemorrhage control by operative or angiographic means. Different detailed algorithms and orders of hemostatic procedures exist, without clear consensus or guidelines, depending on local traditions and institutional setups. Fracture reduction and immediate stabilization with a binder constitute the basis for angiography and embolization (AE) or pelvic packing (PP) in the hemodynamically unstable patient. AE is time consuming and may not be available 24/7, whereas PP offers a quick and technically easy procedure well suited for the patient in extremis. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has also been described as a valuable adjunct in hemostatic non-responders, but merely constitute a bridge to surgical or angiographic hemostasis and its definitive role in DCR is not yet clearly established. A swift algorithmic approach to the hemodynamically unstable pelvic injury patient is required to achieve optimum results. The present paper summarizes the available literature on the acute management of the bleeding pelvic trauma patient, with emphasis on initial assessment and damage control resuscitation including surgical and angiographic hemostatic procedures. Furthermore, initial treatment of open fractures and associated injuries to the nervous and genitourinary system is outlined., (© 2024. The Author(s).)