Intact Configuration Research Articles

Optimization of Carbon-Defect Engineering to Boost Catalytic Ozonation Efficiency of Single Fe─N4 Coordination Motif.

Carbon-defect engineering in single-atom metal-nitrogen-carbon (M─N─C) catalysts by straightforward and robust strategy, enhancing their catalytic activity for volatile organic compounds, and uncovering the carbon vacancy-catalytic activity relationship are meaningful but challenging. In this study, an iron-nitrogen-carbon (Fe─N─C) catalyst is intentionally designed through a carbon-thermal-diffusion strategy, exposing extensively the carbon-defective Fe─N4 sites within a micro-mesoporous carbon matrix. The optimization of Fe─N4 sites results in exceptional catalytic ozonation efficiency, surpassing that of intact Fe─N4 sites and commercial MnO2 by 10 and 312 times, respectively. Theoretical calculations and experimental data demonstrated that carbon-defect engineering induces selective cleavage of C─N bond neighboring the Fe─N4 motif. This induces an increase in non-uniform charges and Fermi density, leading to elevated energy levels at the center of Fe d-band. Compared to the intact atomic configuration, carbon-defective Fe─N4 site is more activated to strengthen the interaction with O3 and weaken the O─O bond, thereby reducing the barriers for highly active surface atomic oxygen (*O/*OO), ultimately achieving efficient oxidation of CH3SH and its intermediates. This research not only offers a viable approach to enhance the catalytic ozonation activity of M─N─C but also advances the fundamental comprehension of how periphery carbon environment influences the characteristics and efficacy of M─N4 sites.

Exact closed-form dynamic stiffness matrix of damaged frames comprising Timoshenko–Ehrenfest beams

The present work proposes the extension of an exact distributional model for cracked beams to include the local influence on axial deformation on shear deformable beams. Axial, shear and flexural concentrated flexibilities are taken into account to model the damaged sections. Shear deformability is accounted for by adopting the Timoshenko–Ehrenfest model and exact closed-form solution of the mode shapes for multiple cracked beams are derived. On this ground, the final achievement of the work consists in the original formulation of the Dynamic Stiffness Matrix (DSM) with multiple cracked sections in exact closed form. The closed-form expression of the DSM allows the assemblage of the global DSM of a structure to conduct the free vibration analysis of damaged framed structures as well as for the study of frames with semi-rigid joints. This approach has the advantage to avoid any numerical procedure for the construction of the DSM as well as the introduction of further degrees of freedom (dofs) in correspondence of the damaged sections, keeping the size of the problem the same as in the intact configuration. Natural frequencies of the frames are determined by means of the Wittrick–Williams algorithm (W–W), then the mode shapes and modal forces are subsequently obtained in closed form. The proposed approach is validated with results available in literature for two portal frames characterized by the presence of cracks and semi-rigid joints, respectively. Finally, the potentiality of the approach, also in view of practical applications, is demonstrated analysing a multi-storey frame with semi-rigid connections.

Cheap organocatalyst diphenyl phosphate for efficient chemical recycling of poly(lactic acid), other polyesters and polycarbonates

Bioplastics are regarded as a sustainable alternative to traditional petroleum-based plastics, particularly poly(lactic acid) (PLA). However, due to the slow biodegradation of PLA and the lack of an overall recycling strategy, its large-scale use could make it an acute source of future plastic pollution. Herein, we find that diphenyl phosphate (DPP), a cheap organocatalyst, can efficiently catalyze PLA hydrolysis into valuable oligomers/lactic acid. Without pressure and organic solvents, under mild conditions with 3.5 wt% DPP and a little water (160 °C, 1.5 h), commercial PLA pellets/products are rapidly converted into oligomers with molecular weight below 500 g/mol by random hydrolysis. DPP can catalyze at least 10 batches of PLA without compromising its catalytic performance, and kilogram-scale PLA degradation is facilely achieved. The DPP-containing oligomers can be used directly to synthesize lactide, and subsequently high-quality PLA is obtained using a well-established industrial route to achieve closed-loop recycling. Meanwhile, an aqueous lactic acid solution with comparable commercial quality and intact configuration retention is harvested. Moreover, DPP can also effectively catalyze the hydrolysis of other polyesters and polycarbonates. Overall, this study is expected to address the environmental and engineering challenges associated with plastic waste disposal, in particular fostering a PLA-based green circular bio-economy.

Hole-driven dynamics of a three-dimensional gravitational liquid curtain

It is known that the disintegration of vertical liquid curtains (sheets) is affected crucially by the amplification of free edge holes forming inside the curtain. This paper aims to investigate the influence of the hole expansion dynamics, driven by the so-called rim retraction, on the breakup of a liquid curtain, in both supercritical (Weber number $We > 1$ ) and subcritical ( $We < 1$ ) conditions. The analysis is based on three-dimensional direct numerical simulations. For a selected supercritical configuration, the steady flow topology is first analysed. The investigation reveals the classic triangular shape regime of the steady curtain, due to the surface-tension-induced borders retraction towards its centre plane. The unsteady dynamics is then investigated as the curtain response to a hole perturbation introduced artificially in the steady flow configuration. The hole evolution determines a rim retraction phenomenon inside the curtain, which is influenced by both capillary and gravity forces. In supercritical conditions, the hole does not influence the curtain flow dynamics in the long-time limit. By reducing the Weber number slightly under the critical threshold ( $We=1$ ), the initial amplification rate of the hole area increases, due to the stronger retraction effect of surface tension acting on the hole rims. The free hole expansion in fully subcritical conditions ( $We < 1$ ) is investigated finally by simulating an edge-free curtain flow. As $We$ decreases progressively, the hole expands while it is convected downstream by gravity acceleration. In the range $0.4< We<1$ , the subcritical curtain returns to the intact unperturbed configuration after the hole expulsion at the downstream outflow. For $We<0.4$ , the surface tension force becomes strong enough to reverse the gravitational motion of the hole top point, which retracts upstream towards the sheet inlet section while expanding along the lateral directions. This last phenomenon causes finally the breakup of the curtain, which results in a columnar regime strictly resembling similar experimental findings of the literature.

DP CHALLENGES IN ANA PLATFORM JACKET INSTALLATION

Installation of jacket platforms requires simultaneous and combined operations of multiple assets. Once the whole process has to be planned, it is necessary to predict in a fast and reliable way the possible weather limitations that may occur during the operations. The paper will present the major challenges of this unusual and innovative Dynamic Positioning analysis which has been carried out for Ana Jacket installation. The obtained results show that the Dynamic Positioning system of the core vessel in intact configuration is capable to hold the position for the investigated vessels' arrangements and design operative weather conditions. Lifting, upending and installation of Ana Jacket were carried out successfully in 2021.

Biomechanical evaluation of syndesmotic fixation techniques via finite element analysis: Screw vs. suture button

Background and ObjectiveTibiofibular syndesmotic injuries may cause degenerative changes, reduction in ankle function and compromising ankle stability. Different fixation techniques try to restore its functionality. Screw-fixation is the gold-standard. Recently, suture-button fixation has aroused the attention because it allows for physiologic micromotion while maintaining an accurate reduction. The aim of this study is to compare the biomechanical behaviour of both fixation techniques using the finite element method. MethodsA three-dimensional finite element model of the tibiofibular joint was reconstructed simulating the intact ankle and the injured syndesmosis. Then, different methods of syndesmosis fixation were analysed: screws (number of cortices, number of screws and distance between screws) and suture buttons (single, double parallel and double divergent with a sensitivity analysis on the pretension forces) configuration. Ligaments and cartilages were included and simulated as spring elements. Physiological loads during stance phase were simulated. ResultsSyndesmosis widening and von Mises stresses were computed. Syndesmosis widening in the injured configuration compromised joint stability (2.06 mm), whereas using a single quadricortical screw (0.18 mm) stiffened the joint. Syndesmosis widening using suture-buttons were closer to syndesmosis widening of the intact ankle configuration (0.97 mm). Von Mises stresses were higher for the titanium screws than for the suture buttons. ConclusionsA detailed biomechanical comparison among different syndesmotic fixation was performed. Suture buttons have advantages with regard to syndesmosis widening in comparison to screw fixation. This fact supports the good long-term clinical results obtained with suture buttons fixation. The proposed methodology could be an efficient tool for preoperative planning.

Seeing Beyond Morphology-Standardized Stress MRI to Assess Human Knee Joint Instability.

While providing the reference imaging modality for joint pathologies, MRI is focused on morphology and static configurations, thereby not fully exploiting the modality’s diagnostic capabilities. This study aimed to assess the diagnostic value of stress MRI combining imaging and loading in differentiating partial versus complete anterior cruciate ligament (ACL)-injury. Ten human cadaveric knee joint specimens were subjected to serial imaging using a 3.0T MRI scanner and a custom-made pressure-controlled loading device. Emulating the anterior-drawer test, joints were imaged before and after arthroscopic partial and complete ACL transection in the unloaded and loaded configurations using morphologic sequences. Following manual segmentations and registration of anatomic landmarks, two 3D vectors were computed between anatomic landmarks and registered coordinates. Loading-induced changes were quantified as vector lengths, angles, and projections on the x-, y-, and z-axis, related to the intact unloaded configuration, and referenced to manual measurements. Vector lengths and projections significantly increased with loading and increasing ACL injury and indicated multidimensional changes. Manual measurements confirmed gradually increasing anterior tibial translation. Beyond imaging of ligament structure and functionality, stress MRI techniques can quantify joint stability to differentiate partial and complete ACL injury and, possibly, compare surgical procedures and monitor treatment outcomes.

Capture and catalytic conversion of lithium polysulfides by metal-doped MoS2 monolayers for lithium–sulfur batteries: A computational study

Abstract Searching for effective anchoring material to capture and convert lithium polysulfides (Li2Sn ) for suppressing their shuttling effects has been a key scientific issue for the development of lithium sulfur (Li–S) batteries with high-efficiency. Herein, by means of density functional theory (DFT) computations, we have explored the potential of doped MoS 2 monolayers with a series of metal atoms in place of Mo or S atom as the anchoring materials for Li–S batteries. Our results revealed that Li2Sn species can be physisorbed on doped MoS2 monolayer by substituting Mo atom with metal dopant , inducing a limited enhancement for the immobilization of Li 2Sn species, as compared with pristine MoS2 monolayer. In contrast, due to the synergistic effects between metal dopant and its adjacent S atoms, the substitution in S atom with metal dopant greatly improves the binding strength of Li2Sn species on MoS2 monolayer, particularly saving the intact Li2Sn configuration. More interestingly, this kind of metal-doped MoS2 monolayer exhibits good catalytic activity for the formation and the decomposition of Li2S in discharge and charge processes. Thus, metal-doped MoS2 monolayers can be utilized as the multifunctional anchoring materials for Li–S batteries by carefully controlling the kinds and sites of dopants in MoS2 monolayer, which opens up a new strategy to further develop high-performance Li–S batteries.

Biomechanics in an Incomplete Versus Complete Supraspinatus Tear: A Cadaveric Study.

Background:Degenerative and traumatic changes to the rotator cuff can result in massive and irreparable rotator cuff tears (RCTs).Purpose/Hypothesis:The study objective was to conduct a biomechanical comparison between a small, incomplete RCT and a large, complete RCT. We hypothesized that the incomplete supraspinatus (SS) tear would lead to an incremental loss of abduction force and preserve vertical position of the humeral head, while a complete SS tear would cause superior humeral migration, decrease functional deltoid abduction force, and increase passive range of motion (ROM).Study Design:Controlled laboratory study.Methods:Six cadaveric shoulders were evaluated using a custom testing apparatus. Each shoulder was subjected to 3 conditions: (1) intact/control, (2) 50%, full-thickness, incomplete SS tear, and (3) 100%, complete SS tear. Deltoid abduction force, superior humeral head migration, and passive ROM were measured in static conditions at 0°, 30°, and 60° of glenohumeral abduction, respectively.Results:The intact SS resulted in a mean deltoid abduction force of 2.5, 3.3, and 3.8 N at 0°, 30°, and 60° of abduction, respectively. Compared with the intact shoulder, there was no significant difference in mean abduction force seen in the incomplete tear, while the force was significantly decreased by 52% at 30° of abduction in the complete tear (P = .009). Compared with the incomplete tear, there were significant decreases in abduction force seen in the complete tear, by 33% and 48% (0.9 N and 1.1 N) at 0° and 30° of abduction, respectively (P = .04 and .004). The intact configuration experienced a mean superior humeral head migration of 1.5, 1.4, and 1.1 mm at 0°, 30°, and 60° of abduction, respectively. The complete tear resulted in a superior migration of 3.0 and 4.4 mm greater than the intact configuration at 0° and 30° of abduction, respectively (P = .001). There was a 5° and 10° increase in abduction ROM with 50% and 100% tears, respectively (P = .003 and .03).Conclusion:An incomplete SS tear does not significantly alter the biomechanics of the shoulder, while a large, complete SS tear leads to a significant superior humeral migration, a decreased deltoid abduction force, and a mild increase in passive ROM.Clinical Relevance:Our findings demonstrate the effects of large SS tears on key biomechanical parameters, as they progress from partial tears.

Ensemble coding of crowd speed using biological motion.

The accurate perception of human crowds is integral to social understanding and interaction. Previous studies have shown that observers are sensitive to several crowd characteristics such as average facial expression, gender, identity, joint attention, and heading direction. In two experiments, we examined ensemble perception of crowd speed using standard point-light walkers (PLW). Participants were asked to estimate the average speed of a crowd consisting of 12 figures moving at different speeds. In Experiment 1, trials of intact PLWs alternated with trials of scrambled PLWs with a viewing duration of 3 seconds. We found that ensemble processing of crowd speed could rely on local motion alone, although a globally intact configuration enhanced performance. In Experiment 2, observers estimated the average speed of intact-PLW crowds that were displayed at reduced viewing durations across five blocks of trials (between 2500 ms and 500 ms). Estimation of fast crowds was precise and accurate regardless of viewing duration, and we estimated that three to four walkers could still be integrated at 500 ms. For slow crowds, we found a systematic deterioration in performance as viewing time reduced, and performance at 500 ms could not be distinguished from a single-walker response strategy. Overall, our results suggest that rapid and accurate ensemble perception of crowd speed is possible, although sensitive to the precise speed range examined.

Negative Pressure Pyrolysis Induced Highly Accessible Single Sites Dispersed on 3D Graphene Frameworks for Enhanced Oxygen Reduction.

Herein, we report a negative pressure pyrolysis to access dense single metal sites (Co, Fe, Ni etc.) with high accessibility dispersed on three-dimensional (3D) graphene frameworks (GFs), during which the differential pressure between inside and outside of metal-organic frameworks (MOFs) promotes the cleavage of the derived carbon layers and gradual expansion of mesopores. In situ transmission electron microscopy and Brunauer-Emmett-Teller tests reveal that the formed 3D GFs possess an enhanced mesoporosity and external surface area, which greatly favor the mass transport and utilization of metal sites. This contributes to an excellent oxygen reduction reaction (ORR) activity (half-wave potential of 0.901 V vs. RHE). Theoretical calculations verify that selective carbon cleavage near Co centers can efficiently lower the overall ORR theoretical overpotential in comparison with intact atomic configuration.

Negative Pressure Pyrolysis Induced Highly Accessible Single Sites Dispersed on 3D Graphene Frameworks for Enhanced Oxygen Reduction

AbstractHerein, we report a negative pressure pyrolysis to access dense single metal sites (Co, Fe, Ni etc.) with high accessibility dispersed on three‐dimensional (3D) graphene frameworks (GFs), during which the differential pressure between inside and outside of metal–organic frameworks (MOFs) promotes the cleavage of the derived carbon layers and gradual expansion of mesopores. In situ transmission electron microscopy and Brunauer–Emmett–Teller tests reveal that the formed 3D GFs possess an enhanced mesoporosity and external surface area, which greatly favor the mass transport and utilization of metal sites. This contributes to an excellent oxygen reduction reaction (ORR) activity (half‐wave potential of 0.901 V vs. RHE). Theoretical calculations verify that selective carbon cleavage near Co centers can efficiently lower the overall ORR theoretical overpotential in comparison with intact atomic configuration.

Biomechanical effects of superior capsular reconstruction in a rotator cuff–deficient shoulder: a cadaveric study

Superior capsular reconstruction (SCR) has been gaining popularity as a treatment for irreparable rotator cuff tears (RCTs), especially in younger patients. This biomechanical study aimed to investigate how SCR affects functional abduction force, humeral head migration, and passive range of motion following an irreparable RCT. We hypothesized that SCR will restore these parameters to nearly intact shoulder levels. Six fresh-frozen cadaveric shoulders were evaluated using a custom biomechanical testing apparatus. Each shoulder was taken through 3 conditions: (1) intact (control); (2) irreparable, complete supraspinatus (SS) tear; and (3) SCR. Functional abduction force, superior humeral head migration, and passive range of motion, including axial shoulder rotation, were measured in static condition at 0°, 30°, and 60° of glenohumeral abduction. Data were analyzed using the paired Student t testor Wilcoxon signed rank test, depending on the results of normality testing. The irreparable SS tear resulted in significantly lower functional abduction force at 30° of abduction (P = .01) and a trend toward a decrease (P = .17) at 60° compared with the intact configuration. SCR shoulders produced greater functional force at 0° compared with the tear configuration (P = .046). Humeral head migration was significantly increased by 4.4 and 3.0 mm at 0° and 30° of abduction, respectively, when comparing the intact vs. SS tear configurations (P = .001). SCR decreased superior migration down to levels of intact shoulders at 0° and 30° of abduction (P = .008 and P = .013, respectively) and was not significantly different from the intact configuration at any angle. SCR decreased passive shoulder extension compared with the tear configuration and increased abduction compared with the intact configuration (P = .007 and P = .03, respectively). The overall arc of axial rotation was not significantly different between SCR and the intact configuration at any angle. In the setting of an irreparable SS tear, SCR restores key biomechanical parameters of the shoulder to intact levels. SCR should be considered for qualifying patients with irreparable RCTs.

Hippocampal and prefrontal contributions to memory retrieval: Examination of immediate early gene, NMDA receptor and environmental interactions.

Animals can use a range of strategies to recall important locations. These include simple stimulus-response strategies and more complex spatial (place) strategies, which are thought to have distinct neural substrates. The hippocampus-and NMDA receptor activation therein-is considered to be crucial for spatial, but not response strategies. The medial prefrontal cortex has also been implicated in memory retrieval; however, evidence concerning its specific role is equivocal. Both hippocampal and prefrontal regions have been associated with flexible behavioural responding (e.g. when task demands change). Here, we investigated the use of spatial and non-spatial strategies in the Morris water maze and their associated brain areas in rats using immediate early gene (IEG) imaging of Zif268 and c-Fos. Specifically, we charted the involvement of hippocampal and prefrontal subregions during retrieval of spatial and non-spatial memories. Behavioural flexibility was also examined using intact and partial cue configurations during recall. Results indicated that regions of both the hippocampus (area CA3) and prefrontal cortex (anterior cingulate cortex) were preferentially engaged in spatial memory recall compared to response learning. In addition, both spatial and non-spatial memories were dependent on NMDA receptor activation. MK801 impaired recall performance across all groups and reduced IEG activation across hippocampal and prefrontal regions. Finally, IEG results revealed divergent patterns of Zif268 and c-Fos activity and support the suggestion that Zif268 plays a functional role in the recall of long-term memories.

DUF3669, a \u201cdomain of unknown function\u201d within ZNF746 and ZNF777, oligomerizes and contributes to transcriptional repression

BackgroundZNF746 and ZNF777 belong to a subset of the large Krüppel-associated box (KRAB) zinc finger (ZNF) transcription factor family. They contain, like four other members in human, an additional conserved domain, the “domain of unknown function 3669” (DUF3669). Previous work on members of this subfamily suggested involvement in transcriptional regulation and aberrant ZNF746 overexpression leads to neuronal cell death in Parkinson’s disease.ResultsHere we demonstrate that N-terminal protein segments of the ZNF746a major isoform and ZNF777 act in concert to exert moderate transcriptional repression activities. Full potency depended on the intact configuration consisting of DUF3669, a variant KRAB domain and adjacent sequences. While DUF3669 contributes an intrinsic weak inhibitory activity, the isolated KRAB-AB domains did not repress. Importantly, DUF3669 provides a novel protein-protein interaction interface and mediates direct physical interaction between the members of the subfamily in oligomers. The ZNF746 protein segment encoded by exons 5 and 6 boosted repressor potency, potentially due to the presence of an acceptor lysine for sumoylation at K189. Repressor activity of the potent canonical ZNF10 KRAB domain was not augmented by heterologous transfer of DUF3669, pointing to the importance of context for DUF3669’s impact on transcription. Neither ZNF746a nor ZNF777 protein segments stably associated with TRIM28 within cells. Isoform ZNF746b that contains, unlike the major isoform, a full-length KRAB-A subdomain, displayed substantially increased repressor potency. This increase is due to canonical mechanisms known for KRAB domains since it did not take place in HAP1 knockout models of TRIM28 and SETDB1. A glycine to glutamic acid replacement that complies with a bona fide conserved “MLE” sequence within KRAB-A led to a further strong gain in repressor potency to levels comparable to those of the canonical ZNF10 KRAB domain. Each gain of repressive activity was accompanied by an enhanced interaction with TRIM28 protein.ConclusionDUF3669 adds a protein-protein interaction surface to a subgroup of KRAB-ZNF proteins within an N-terminal configuration with variant KRAB and adjacent sequences likely regulated by sumoylation. DUF3669 contributes to transcriptional repression strength and its homo- and hetero-oligomerization characteristics probably extended the regulatory repertoire of KRAB-ZNF transcription factors during amniote evolution.

H induced decohesion of an Al grain boundary investigated with first principles: General conditions for instant breakage and local delayed fracture

The uniaxial tensile test response of a H decorated Σ5 [1 0 0] twist grain boundary (GB) in face-centred-cubic Al has been examined with first principles. The impurity shows a strong tendency to relocate during loading. To capture these H movements, the standard model framework was extended to probe loading-unloading hysteresis. Due to the strong monotonic decrease in the H formation energy with rising GB elongation, the maximum tensile stress accepted by the H decorated GB in the slow fracture limit generally is reached before breakage becomes thermodynamically favourable. For any intact GB configuration visited upon exceeding this stress, the assumption of global chemical equilibrium is argued to be violated. Moreover, while breakage remains ensured from the slow fracture limit considerations, it may in practice require the influx of H to the GB vicinity. A quantitative analysis of GB destabilisation in this scenario requires multi-scale modelling even in the slow fracture limit.

Modal identification of localised damage in beams and trusses: experimental and numerical results

The paper discusses the possibility of detecting local damages in complex structures typical of civil engineering, as multispan beams and trusses. Namely, it describes a procedure to identify localised cracks in structures in the elastic range of behaviour using only the values of natural frequencies in the intact configuration and in the damaged one evaluated by means of dynamic tests. The error minimisation procedure described in the paper selects the solution within a set of finite element models that simulate a range of positions and levels of damage, by identifying the damaged configuration as the one whose modal frequencies minimise the least-square difference with the measured data. The accuracy of the method is first investigated by applying it to the damage detection of a two-span steel beam, whose modal frequencies were obtained by means of experimental tests. To explore the accuracy of the proposed procedure, numerically simulated data with random noise were also generated for several positions and levels of damage and for different values of the random noise. The procedure was then extended, by means of numerical simulations, to the case of a beam with two localised damages. Finally, the procedure proposed for multispan beams is adapted to the damage identification of plane truss structures.

Structural determination of the large photosystem II–light-harvesting complex II supercomplex of Chlamydomonas reinhardtii using nonionic amphipol

In photosynthetic organisms, photosystem II (PSII) is a large membrane protein complex, consisting of a pair of core complexes surrounded by an array of variable numbers of light-harvesting complex (LHC) II proteins. Previously reported structures of the PSII-LHCII supercomplex of the green alga Chlamydomonas reinhardtii exhibit significant structural heterogeneity, but recently improved purification methods employing ionic amphipol A8-35 have enhanced supercomplex stability, providing opportunities for determining a more intact structure. Herein, we present a 5.8 Å cryo-EM map of the C. reinhardtii PSII-LHCII supercomplex containing six LHCII trimers (C2S2M2L2). Utilizing a newly developed nonionic amphipol-based purification and stabilizing method, we purified the largest photosynthetic supercomplex to the highest percentage of the intact configuration reported to date. We found that the interprotein distances within the light-harvesting complex array in the green algal photosystem are larger than those previously observed in higher plants, indicating that the potential route of energy transfer in the PSII-LHCII supercomplex in green algae may be altered. Interestingly, we also observed an asymmetric PSII-LHCII supercomplex structure comprising C2S2M1L1 in the same sample. Moreover, we found a new density adjacent to the PSII core complex, attributable to a single-transmembrane helix. It was previously unreported in the cryo-EM maps of PSII-LHCII supercomplexes from land plants.

Spectroscopic and Electrochemical Features of Glucose Oxidase Incorporation into Polyaniline-Cobaltous Oxalate Nano-complex

Nano-complex as enzyme carrier was prepared via hybridization of nano-scale cobaltous oxalate with conductive polymer: polyaniline. Spectrometric means and electrochemical technique were proposed to explore the influence of interaction between nano-composite and redox protein on structural features, dynamics of electron shuttle and catalysis of immobilized enzyme. Results indicated that collaboration of π–π stacking effect as well as the complexation of metal ions in nano-composite with cofactors in enzyme molecule could lead to the firm linkage of glucose oxidase to the matrix of nano-composite. The ligation would cause orientated attachment of enzyme molecules onto the surface of nano-complex. Synergistic effect would not only enhance the enzyme loading capacity of carrier but also facilitate the direct electrochemistry of tethered enzyme molecules with intact structure and configuration of cofactor. However the complexation would cripple the enzymatic catalysis in electro-oxidation of glucose in spite of high affinity to glucose for glucose oxidase integration into nano-composite. Coordination of metal ions within nano-composite with cofactor of glucose oxidase (GOx) would lead to formation of composite with crippled emission fluorescence and hinder the electro-oxidation of glucose.

Finite element analysis of the pelvis including gait muscle forces: an investigation into the effect of rami fractures on load transmission

BackgroundThe objective of the study is to investigate the load transmission within the pelvic ring under physiological loading during gait and to correlate these results with clinical findings. In a second approach, we analysed how load distribution is altered by fractures of the anterior pelvic ring.MethodsMuscle forces and joint reaction forces are calculated by inverse dynamics and implemented in a finite element pelvis model including the joints.ResultsWith the intact configuration and according to the moment of the gait, left and right superior and inferior rami show the highest stresses of the model, corresponding to the typical location of an anterior pelvic ring fracture. A superior ramus fracture induces larger stresses to the lower ramus and a slight increase of stresses on the posterior structures. A total disruption of anterior rami redirects the loads to the back of the pelvis and introduces significantly higher stresses on the posterior structures.ConclusionsThis investigation enhances the understanding of the biomechanics of the pelvis and highlights the important role of the rami in load carrying and in maintaining integrity of the pelvic ring.