Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO2) semiconductor materials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applications. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 structure, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization of visible light, including non metal and/or metal doping, dye sensitization and coupling semiconductors are discussed. Emphasis is given to the origin of visible light absorption and the reactive oxygen species generated, deduced by physicochemical and photoelectrochemical methods. Various applications of VLA TiO2, in terms of environmental remediation and in particular water treatment, disinfection and air purification, are illustrated. Comprehensive studies on the photocatalytic degradation of contaminants of emerging concern, including endocrine disrupting compounds, pharmaceuticals, pesticides, cyanotoxins and volatile organic compounds, with VLA TiO2 are discussed and compared to conventional UV-activated TiO2 nanomaterials. Recent advances in bacterial disinfection using VLA TiO2 are also reviewed. Issues concerning test protocols for real visible light activity and photocatalytic efficiencies with different light sources have been highlighted.

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A review on the visible light active titanium dioxide photocatalysts for environmental applications

Hydrogel delivery systems can leverage therapeutically beneficial outcomes of drug delivery and have found clinical use. Hydrogels can provide spatial and temporal control over the release of various therapeutic agents, including small-molecule drugs, macromolecular drugs and cells. Owing to their tunable physical properties, controllable degradability and capability to protect labile drugs from degradation, hydrogels serve as a platform in which various physiochemical interactions with the encapsulated drugs control their release. In this Review, we cover multiscale mechanisms underlying the design of hydrogel drug delivery systems, focusing on physical and chemical properties of the hydrogel network and the hydrogel-drug interactions across the network, mesh, and molecular (or atomistic) scales. We discuss how different mechanisms interact and can be integrated to exert fine control in time and space over the drug presentation. We also collect experimental release data from the literature, review clinical translation to date of these systems, and present quantitative comparisons between different systems to provide guidelines for the rational design of hydrogel delivery systems.

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Designing hydrogels for controlled drug delivery.

Nature’s hierarchical materials

Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

MUCKE aims to mine a large volume of images, to structure them conceptually and to use this conceptual structuring in order to improve large-scale image retrieval. The last decade witnessed important progress concerning low-level image representations. However, there are a number problems which need to be solved in order to unleash the full potential of image mining in applications. The central problem with low-level representations is the mismatch between them and the human interpretation of image content. This problem can be instantiated, for instance, by the incapability of existing descriptors to capture spatial relationships between the concepts represented or by their incapability to convey an explanation of why two images are similar in a content-based image retrieval framework. We start by assessing existing local descriptors for image classification and by proposing to use co-occurrence matrices to better capture spatial relationships in images. The main focus in MUCKE is on cleaning large scale Web image corpora and on proposing image representations which are closer to the human interpretation of images. Consequently, we introduce methods which tackle these two problems and compare results to state of the art methods. Note: some aspects of this deliverable are withheld at this time as they are pending review. Please contact the authors for a preview.

http://ieeexplore.ieee.org/iel2/4524/12820/00592460.pdf

Image Processing

The present invention relates to a therapeutic substance and/or medicament and methods relating to the use of said substance and/or medicament for skeletal muscle regeneration using mesenchymal stem cells (MSCs) which can be applied directly or shortly after muscle damage or injury.

Skeletal muscle regeneration using mesenchymal stem cells

While the axolotl's ability to completely regenerate amputated limbs is well known and studied, the mechanism of axolotl bone fracture healing remains poorly understood. One reason might be the lack of a standardized fracture fixation in axolotl. We present a surgical technique to stabilize the osteotomized axolotl femur with a fixator plate and compare it to a non-stabilized osteotomy and to limb amputation. The healing outcome was evaluated 3 weeks, 3, 6 and 9 months post-surgery by microcomputer tomography, histology and immunohistochemistry. Plate-fixated femurs regained bone integrity more efficiently in comparison to the non-fixated osteotomized bone, where larger callus formed, possibly to compensate for the bone fragment misalignment. The healing of a non-critical osteotomy in axolotl was incomplete after 9 months, while amputated limbs efficiently restored bone length and structure. In axolotl amputated limbs, plate-fixated and non-fixated fractures, we observed accumulation of PCNA+ proliferating cells at 3 weeks post-injury similar to mouse. Additionally, as in mouse, SOX9-expressing cells appeared in the early phase of fracture healing and amputated limb regeneration in axolotl, preceding cartilage formation. This implicates endochondral ossification to be the probable mechanism of bone healing in axolotls. Altogether, the surgery with a standardized fixation technique demonstrated here allows for controlled axolotl bone healing experiments, facilitating their comparison to mammals (mice). 

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The specialist in regeneration—the Axolotl—a suitable model to study bone healing?

Introduction: It is well known that rupture of the ACL does not only modify movement patterns of the lower limb, but also influences muscle activation, and hence results in a movement strategy that is thought to compensate for pain and joint instability by actively contracting and co-contracting local muscles during dynamic activities. The amount of additional joint stability provided by muscle activation remains unclear, but the additional muscular forces are thought to raise joint loading in a process that could play a key role in the subsequent clinically observed degenerative changes to the joint, including osteoarthritis (OA). By developing a novel technique to allow assessment of tibio-femoral kinematics, this study aimed to define the role of passive joint stability on active tibio-femoral kinematics during walking. Methods: Using motion capture, together with combinations of advanced techniques for assessing skeletal kinematics (SARA [1], SCoRE [2], OCST [3]), a novel non-invasive approach to evaluate dynamic tibio-femoral motion was tested in 8 healthy subjects. Here, the coefficient of variation (CV) was used in order to test the variability in A-P translation between multiple repetitions of walking trials. The intra-class correlation was calculated using ICC(3,1), to assess the intra-subject repeatability of A-P translation as well as the range of tibio-femoral A-P translation (difference between the minimum and maximum A-P movement over an entire gait cycle) between repetitions. The passive (KT1000) and active tibio-femoral joint stability was then examined in 13 patients with ACL rupture and compared to their healthy contralateral limbs. After verification using multi-factorial ANOVA analyses that ACL deficiency has an effect on A-P translation, a post-hoc test was applied to determine the magnitude of the difference in A-P translation between ACL ruptured and healthy (contralateral) knees. Results: The mean CV across all 16 healthy knees showed 5.2% variation (SD 1.2%) in A-P translation, demonstrating the high repeatability of the novel approach for assessing tibio-femoral kinematics between trials. Furthermore, excellent reliabilities were observed for both A-P translation over an entire gait cycle (mean ICC(3,1) = 0.92) as well as the range of A-P translation (mean ICC(3,1) = 0.98) between repetitions in individuals. The femora of the ACL ruptured knees generally remained more posterior relative to the tibia over the walking cycles compared to the healthy contralateral limbs. Surprisingly, the mean active range of tibio-femoral anterior-posterior International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine 9 th Biennial ISAKOS Congress • May 12-16, 2013 • Toronto, Canada ISAKOS

ACL Deficient Patients With Passive Knee Joint Instability Overcompensate During Active Movements

Total hip arthroplasty (THA) is an extremely successful treatment strategy. Patient expectations, however, have increased; if not properly guided by surgeons, at present, patients expect next to pain-free restoration of the joint and a fast return to work and sports. While the revision rates after THA also increased in younger patients, knowledge on musculoskeletal loads still remains sparse, and the current recommendations on postoperative rehabilitation are based on expert opinions only. The aim of this study was to unravel biomechanical contact conditions in “working age” (<60 years, 53.5 ± 3.0 years) and “retirement age” (>60 years, 67.7 ± 8.6 years) patients during activities recommended post-THA. We hypothesized that working age patients would show substantially increased hip contact loads compared to older patients. The in vivo joint contact force (F res) and torsion torque (M tors), reflecting the main contact load situation, experienced during activities of daily living and sports activities were measured in a unique group of 16 patients with instrumented THA. We summarized patient activities and sports recommendations after THA mentioned within the literature using PubMed (without claim of completeness). The measurements showed that younger working age patients experienced significant (p = 0.050) increased M tors (21.52 ± 9.11 Nm) than older retirement age patients (13.99 ± 7.89 Nm) by walking. Bowling, as a recommended low-impact sport, was associated with F res of up to 5436 N and M tors of up to 108 Nm in the working age group, which were higher than the F res (5276 N) and M tors (71 Nm) during high-impact soccer. Based on our results, age was proven to be a discriminator in joint loading, with working age patients presenting with increased loads compared to retirement age patients, already during daily activities. The current patient recommendations have led to further increased joint loadings. If THA cannot be delayed in a patient, we propose counselling patients on a carefully considered return to sports, focusing on low-impact activities, as indicated hereby. The findings from this work illustrate the need to provide critical feedback to patient expectations when returning to work and sports activities. Patients returning to more intensive sports activities should be carefully monitored and advised to avoid as much overloading as possible.

Georg N. Duda

Papers

Skeletal muscle regeneration using mesenchymal stem cells

The specialist in regeneration—the Axolotl—a suitable model to study bone healing?

ACL Deficient Patients With Passive Knee Joint Instability Overcompensate During Active Movements

Overstretching Expectations May Endanger the Success of the “Millennium Surgery”

Aging and Injury Affect Nuclear Shape Heterogeneity in Tendon.