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https://www.readbyqxmd.com/read/29244945/pd-catalyzed-aerobic-oxidation-reactions-strategies-to-increase-catalyst-lifetimes
#1
Wilson Ho, Kevin Chung, Andrew J Ingram, Robert M Waymouth
The palladium complex [(neocuproine)Pd(μ-OAc)]2[OTf]2 (1, neocuproine = 2,9-dimethyl-1,10-phenanthroline) is an effective catalyst precursor for the selective oxidation of primary and secondary alcohols, vicinal diols, polyols, and carbohydrates. Both air and benzoquinone can be used as terminal oxidants, but aerobic oxidations are accompanied by oxidative degradation of the neocuproine ligand, thus necessitating high Pd loadings. Several strategies to improve aerobic catalyst lifetimes were devised, guided by mechanistic studies of catalyst deactivation...
December 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29244887/carbon-fiber-framework-for-full-arch-implant-supported-fixed-dental-prostheses-supporting-resin-based-composite-and-lithium-disilicate-ceramic-crowns-case-report-and-description-of-features
#2
Giuseppe Castorina
This case report presents a new approach for shock-absorbing carbon-fiber composite frameworks for full-arch implant-supported fixed dental prostheses supporting resin-based and lithium disilicate ceramic crowns. It describes the characteristics of the materials used, the procedures for implementing the framework, and the requirements to achieve the best mechanical and clinical properties. The result is a full-arch prosthesis with masticatory load shock-absorption capacities, chemical bonding between materials, good esthetics, and wear similar to natural enamel...
December 15, 2017: International Journal of Periodontics & Restorative Dentistry
https://www.readbyqxmd.com/read/29244883/effects-of-mechanical-repetitive-load-on-bone-quality-around-implants-in-rat-maxillae
#3
Yusuke Uto, Shinichiro Kuroshima, Takayoshi Nakano, Takuya Ishimoto, Nao Inaba, Yusuke Uchida, Takashi Sawase
Greater understanding and acceptance of the new concept "bone quality", which was proposed by the National Institutes of Health and is based on bone cells and collagen fibers, are required. The novel protein Semaphorin3A (Sema3A) is associated with osteoprotection by regulating bone cells. The aims of this study were to investigate the effects of mechanical loads on Sema3A production and bone quality based on bone cells and collagen fibers around implants in rat maxillae. Grade IV-titanium threaded implants were placed at 4 weeks post-extraction in maxillary first molars...
2017: PloS One
https://www.readbyqxmd.com/read/29244508/diffusion-of-supercritical-fluids-through-single-layer-nanoporous-solids-theory-and-molecular-simulations
#4
Fouad Oulebsir, Romain Vermorel, Guillaume Galliero
With the advent of graphene material, membranes based on single-layer nanoporous solids appear as promising devices for fluid separation, be it liquid or gaseous mixtures. The design of such architectured porous materials would greatly benefit from accurate models that can predict their transport and separation properties. More specifically, there is no universal understanding of how parameters such as temperature, fluid loading conditions or the ratio of the pore size to the fluid molecular diameter influence the permeation process...
December 15, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29243760/augmenting-static-and-dynamic-mechanical-strength-of-carbon-nanotube-epoxy-soft-nanocomposites-via-modulation-of-purification-and-functionalization-routes
#5
Beant Kaur Billing, Purbarun Dhar, Narinder Singh, Prabhat K Agnihotri
A detailed experimental investigation was carried out to establish the relationship between CNT purification and functionalization routes and the average response of CNT/epoxy nanocomposites under static and dynamic loading. It was shown that the relative improvement in the mechanical properties of the epoxy matrix due to the addition of CNTs depends on the choice of purification and functionalization steps. A better dispersion of CNTs was recorded for the functionalized CNTs as compared to the oxidized and CVD grown CNTs...
December 15, 2017: Soft Matter
https://www.readbyqxmd.com/read/29243192/a-novel-personalized-3d-injectable-protein-scaffold-for-regenerative-medicine
#6
Eduardo Anitua, Ander Pino, María Troya, Pedro Jaén, Gorka Orive
Biomaterials should be designed to closely resemble the characteristics and functions of the native extracellular matrix to provide mechanical support and signals to direct biological events. Here we have developed a novel injectable plasma rich in growth factors (PRGF-Endoret)-based formulation that combines a thermal-denaturation step of plasma with an autologous fibrin crosslinking. Rheological and mechanical properties were evaluated. Additionally, the microstructure and biological capacity of the biomaterial was also characterized...
December 14, 2017: Journal of Materials Science. Materials in Medicine
https://www.readbyqxmd.com/read/29243185/effect-of-fiber-post-length-and-abutment-height-on-fracture-resistance-of-endodontically-treated-premolars-prepared-for-zirconia-crowns
#7
Jie Lin, Jukka Pekka Matinlinna, Akikazu Shinya, Michael George Botelho, Zhiqiang Zheng
The purpose of this study was to compare the fracture resistance, mode of fracture, and stress distribution of endodontically treated teeth prepared with three different fiber post lengths and two different abutment heights, using both experimental and finite element (FE) approaches. Forty-eight human maxillary premolars with two roots were selected and endodontically treated. The teeth were randomly distributed into six equally sized groups (n = 8) with different combinations of post lengths (7.5, 11, and 15 mm) and abutment heights (3 and 5 mm)...
December 14, 2017: Odontology
https://www.readbyqxmd.com/read/29243027/lactobacillus-rhamnosus-reduces-parasite-load-on-toxocara-canis-experimental-infection-in-mice-but-has-no-effect-on-the-parasite-in-vitro
#8
Débora Liliane Walcher, Luis Augusto Xavier Cruz, Paula de Lima Telmo, Lourdes Helena Rodrigues Martins, Luciana Farias da Costa de Avila, Maria Elisabeth Aires Berne, Carlos James Scaini
Human toxocariasis is a neglected global parasitic zoonosis. The efficacy of drug treatment for this disease has been hindered by the biological complexity of the main etiological agent, the nematode Toxocara canis. Experimental studies have shown the potential of probiotics to promote a reduction in the parasite load of T. canis larvae. This study aimed to evaluate the effect of probiotic Lactobacillus rhamnosus ATCC 7469 on the parasite load of BALB/c mice with acute toxocariasis and evaluate the direct effect of this probiotic on T...
December 14, 2017: Parasitology Research
https://www.readbyqxmd.com/read/29242161/preparation-of-dexamethasone-loaded-biphasic-calcium-phosphate-nanoparticles-collagen-porous-composite-scaffolds-for-bone-tissue-engineering
#9
Ying Chen, Naoki Kawazoe, Guoping Chen
Although bone is regenerative, its regeneration capacity is limited. For bone defects beyond a critical size, further intervention is required. As an attractive strategy, bone tissue engineering (bone TE) has been widely investigated to repair bone defects. However, the rapid and effective bone regeneration of large non-healing defects is still a great challenge. Multifunctional scaffolds having osteoinductivity and osteoconductivity are desirable to fasten functional bone tissue regeneration. In the present study, biomimetic composite scaffolds of collagen and biphasic calcium phosphate nanoparticles (BCP NPs) with a controlled release of dexamethasone (DEX) and the controlled pore structures were prepared for bone TE...
December 11, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/29242158/additively-manufactured-biodegradable-porous-magnesium
#10
Y Li, J Zhou, P Pavanram, M A Leeflang, L I Fockaert, B Pouran, N Tümer, K-U Schröder, J M C Mol, H Weinans, H Jahr, A A Zadpoor
An ideal bone substituting material should be bone-mimicking in terms of mechanical properties, present a precisely controlled and fully interconnected porous structure, and degrade in the human body to allow for full regeneration of large bony defects. However, simultaneously satisfying all these three requirements has so far been highly challenging. Here we present topologically ordered porous magnesium (WE43) scaffolds based on the diamond unit cell that were fabricated by selective laser melting (SLM) and satisfy all the requirements...
December 11, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/29242100/takotsubo-is-not-a-cardiomyopathy
#11
Francesco Pelliccia, Gianfranco Sinagra, Perry Elliott, Guido Parodi, Cristina Basso, Paolo G Camici
Unraveling the mechanisms underlying Takotsubo (TTS) leads to question the current inclusion of the condition within the spectrum of cardiomyopathies. Indeed, the clinical presentation and pathophysiology of TTS clearly differ from cardiomyopathies, i.e. diseases of heart muscle unexplained by abnormal loading conditions or coronary artery disease, which cannot recover spontaneously and may cause sudden death often in minimally symptomatic individuals or result in a gradual deterioration in ventricular function and end-stage heart failure...
December 9, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/29241544/dissociation-of-rad51-presynaptic-complexes-and-heteroduplex-dna-joints-by-tandem-assemblies-of-srs2
#12
Kyle Kaniecki, Luisina De Tullio, Bryan Gibb, Youngho Kwon, Patrick Sung, Eric C Greene
Srs2 is a superfamily 1 (SF1) helicase and antirecombinase that is required for genome integrity. However, the mechanisms that regulate Srs2 remain poorly understood. Here, we visualize Srs2 as it acts upon single-stranded DNA (ssDNA) bound by the Rad51 recombinase. We demonstrate that Srs2 is a processive translocase capable of stripping thousands of Rad51 molecules from ssDNA at a rate of ∼50 monomers/s. We show that Srs2 is recruited to RPA clusters embedded between Rad51 filaments and that multimeric arrays of Srs2 assemble during translocation on ssDNA through a mechanism involving iterative Srs2 loading events at sites cleared of Rad51...
December 12, 2017: Cell Reports
https://www.readbyqxmd.com/read/29240039/an-overview-of-low-back-pain-and-occupational-exposures-to-whole-body-vibration-and-mechanical-shocks
#13
Massimo Bovenzi, Marianne Schust, Marcella Mauro
This paper offers an overview of the relation of low back pain (LBP) to occupational exposures to whole-body vibration (WBV) and mechanical shocks. LBP is a condition of multifactorial origin and is a very common health problem in the general population. Among occupational risk factors, epidemiological studies of driving occupations have provided evidence for strong associations between LBP and occupational exposures to WBV and mechanical shocks. Since it is hard to separate the contribution of WBV exposure to disorders in the lower back from that of other individual, ergonomic or psychosocial risk factors, a quantitative exposure-response relationship for WBV cannot be outlined precisely...
December 14, 2017: La Medicina del Lavoro
https://www.readbyqxmd.com/read/29239479/investigating-canine-elbow-joint-stabilisation-through-mechanical-constraints-of-the-deep-fascia-and-other-soft-tissues
#14
Timothy E Chong, Helen M S Davies
The objective of this research was to investigate how the range of flexion and extension of the canine elbow joint is constrained by the mechanical connections and attachments of soft tissue structures. The skin, a section of deep fascia and several muscles from both forelimbs from six adult greyhounds and seven other breeds were sequentially transected or removed, over 13 steps. During each step, repeated measurements of elbow flexion and extension were recorded using a goniometer. Only marginally significant changes to the range of flexion occurred in any of the 13 steps or overall for the greyhounds...
December 14, 2017: Journal of Anatomy
https://www.readbyqxmd.com/read/29239252/single-bundle-vs-double-bundle-anatomical-reconstruction-of-the-thumb-ulnar-collateral-ligament-biomechanical-study
#15
Megan L Jimenez, Stephen D Hioe, Amir R Kachooei, Jonathan W Shearin, Christopher M Jones, Michael Rivlin
BACKGROUND: The goal of this study is to compare the biomechanical properties of anatomic (double-bundle) versus single-bundle reconstruction of the thumb metacarpophalangeal (MCP) joint ulnar collateral ligament (UCL) in a cadaveric model. METHODS: Twelve fresh frozen cadaver hands were randomly assigned to single- or double-bundle reconstruction groups using a palmaris longus autograft and tenodesis screws. Two blinded examiners performed mechanical testing and measurements using fluoroscopic imaging...
December 1, 2017: Hand: Official Journal of the American Association for Hand Surgery
https://www.readbyqxmd.com/read/29239103/out-of-plane-3d-printed-microfibers-improve-the-shear-properties-of-hydrogel-composites
#16
Mylène de Ruijter, Andrei Hrynevich, Jodie N Haigh, Gernot Hochleitner, Miguel Castilho, Jürgen Groll, Jos Malda, Paul D Dalton
One challenge in biofabrication is to fabricate a matrix that is soft enough to elicit optimal cell behavior while possessing the strength required to withstand the mechanical load that the matrix is subjected to once implanted in the body. Here, melt electrowriting (MEW) is used to direct-write poly(ε-caprolactone) fibers "out-of-plane" by design. These out-of-plane fibers are specifically intended to stabilize an existing structure and subsequently improve the shear modulus of hydrogel-fiber composites. The stabilizing fibers (diameter = 13...
December 14, 2017: Small
https://www.readbyqxmd.com/read/29238811/displacement-propagation-and-nonaffinity-in-collagen-networks-due-to-local-contraction
#17
Peter Grimmer, Jacob Notbohm
The extracellular matrix provides macroscale structure to tissues and microscale guidance for cell contraction, adhesion, and migration. The matrix is composed of a network of fibers, which each deform by stretching, bending, and buckling. Whereas the mechanics has been well characterized in uniform shear and extension, the response to more general loading conditions remains less clear, because the associated displacement fields cannot be predicted a priori. Studies simulating contraction, such as due to a cell, have observed displacements that propagate over a long range, suggesting mechanisms such as reorientation of fibers toward directions of tensile force and nonlinearity due to buckling of fibers under compression...
December 13, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/29237822/potassium-regulated-distal-tubule-wnk-bodies-are-kidney-specific-wnk1-dependent
#18
Cary R Boyd-Shiwarski, Daniel J Shiwarski, Ankita Roy, Lubika J Nkashama, Hima N Namboodiri, Jian Xie, Kara L McClain, Allison Marciszyn, Thomas R Kleyman, Roderick J Tan, Donna B Stolz, Manojkumar A Puthenveedu, Chou-Long Huang, Arohan R Subramanya
With-No-Lysine (WNK) kinases coordinate volume and potassium homeostasis by regulating renal tubular electrolyte transport. In the distal convoluted tubule (DCT), potassium imbalance causes WNK signaling complexes to concentrate into large discrete foci, which we call "WNK bodies." Though these structures have been reported previously, the mechanisms that drive their assembly remain obscure. Here, we show that kidney-specific WNK1 (KS-WNK1), a truncated kinase-defective WNK1 isoform that is highly expressed in the DCT, is critical for WNK body formation...
December 13, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/29237574/late-rise-in-hemolymph-osmolality-in-macrobrachium-acanthurus-diadromous-freshwater-shrimp-exposed-to-brackish-water-early-reduction-in-branchial-na-k-pump-activity-but-stable-muscle-hsp70-expression
#19
Carolina A Freire, Anieli C Maraschi, Alessandra F Lara, Enelise M Amado, Viviane Prodocimo
Some Macrobrachium shrimps (Caridea, Palaemonidae) are diadromous; freshwater adults are truly euryhaline, while larvae need saline water for development. Branchial Na+/K+-ATPase (NKA) and carbonic anhydrase (CA) are involved in NaCl absorption in freshwater. This study aimed at verifying the time course of the osmoregulatory response of adult Macrobrachium acanthurus to high salinity brackish water (20‰), from the first 30min to 5days. The goal was to detect possible transition from hyper- to hyporegulation, the putative involvement of branchial NKA and CA, or the induction of muscular HSP70 expression...
December 10, 2017: Comparative Biochemistry and Physiology. Part B, Biochemistry & Molecular Biology
https://www.readbyqxmd.com/read/29237515/pulsus-alternans-in-a-child-with-dilated-cardiomyopathy
#20
Hasti Sanandajifar, Sarosh P Batlivala
A previously healthy 21-month-old presented with new-onset dilated cardiomyopathy. Evaluation noted pulsus alternans, with beat-to-beat alternations in aortic pulse wave amplitude, both clinically and on diagnostic studies. Pulsus alternans is an infrequent, complex pathophysiologic sign often associated with severe heart failure. The mechanisms are incompletely understood, but theorised aetiologies include beat-to-beat changes in left ventricular loading conditions, variations in myocardial oxygen supply/demand, and alternations in myocardial contractility...
December 14, 2017: Cardiology in the Young
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