325 research outputs found
Relationships between the Sakarya Zone and the Ankara–Erzincan suture (central-northern Turkey): geological and petrographic data from the Ankara–Çankiri, Çorum and Amasya areas
Wall Microstructures of High Aspect Ratio Enabled by NearâField Electrospinning
Near-field electrospinning (NFES) holds the potential to develop into a versatile additive nanomanufacturing platform. However, the impact of a variety of processing variables remains unresolved.Herein, the effect of solvents used to prepare suitable solutions for 3D microstructuring by electrospinning is studied. 3D straight walls of stacked fibers are fabricated using a layer-by-layer fiber deposition approach. The effect of the choice of substrate material is also explored. The results show that a high vapor pressure, and a low dielectric constant of the solvent, as well as a high substrate conductivity facilitate improved stacking of fiber layers. Utilizing these conditions, 3D stacked walls of polyethylene oxide are fabricated, and a maximum aspect ratio of 191.7â±â52.6, while using a chromium/gold substrate and dichloromethane/methanol as the solvent is achieved
Physicochemical and Antibacterial Characterisation of a Novel Fluorapatite Coating
Peri-implantitis remains the major impediment to the long-term use of dental
implants. With increasing concern over growing antibiotic resistance there is
considerable interest in the preparation of antimicrobial dental implant coatings that
also induce osseointegration. One such potential coating material is fluorapatite
(FA). The aim of this study was to relate the antibacterial effectiveness of FA
coatings against pathogens implicated in peri-implantitis to the physicochemical
properties of the coating. Ordered and disordered FA coatings were produced on the
under and upper surface of stainless steel (SS) discs respectively, using a
hydrothermal method. Surface charge, surface roughness, wettability and fluoride
release were measured for each coating. Surface chemistry was assessed by X-ray
photoelectron spectroscopy and FA crystallinity by X-ray diffraction. Antibacterial
activity against periodontopathogens was assessed in vitro using viable counts,
confocal and scanning electron (SEM) microscopies. SEM showed that the
hydrothermal method produced FA coatings predominately aligned perpendicular to
the SS substrate or disordered FA coatings consisting of randomly aligned rod-like
crystals. Both FA coatings significantly reduced the growth of all the examined
bacterial strains in comparison to the control. The FA coatings, and especially the
disordered ones, presented significantly lower charge, higher roughness and area
when compared to the control, enhancing bacteriaâmaterial interactions and
therefore bacterial deactivation by fluoride ions. The ordered FA layer reduced not
only bacterial viability but adhesion too. Ordered FA crystals produced as a potential
novel implant coating showed significant antibacterial activity against bacteria
implicated in peri-implantitis which could be explained by a detailed understanding of
their physicochemical properties
U and Th content in the Central Apennines continental crust: a contribution to the determination of the geo-neutrinos flux at LNGS
The regional contribution to the geo-neutrino signal at Gran Sasso National
Laboratory (LNGS) was determined based on a detailed geological, geochemical
and geophysical study of the region. U and Th abundances of more than 50
samples representative of the main lithotypes belonging to the Mesozoic and
Cenozoic sedimentary cover were analyzed. Sedimentary rocks were grouped into
four main "Reservoirs" based on similar paleogeographic conditions and
mineralogy. Basement rocks do not outcrop in the area. Thus U and Th in the
Upper and Lower Crust of Valsugana and Ivrea-Verbano areas were analyzed. Based
on geological and geophysical properties, relative abundances of the various
reservoirs were calculated and used to obtain the weighted U and Th abundances
for each of the three geological layers (Sedimentary Cover, Upper and Lower
Crust). Using the available seismic profile as well as the stratigraphic
records from a number of exploration wells, a 3D modelling was developed over
an area of 2^{\circ}x2^{\circ} down to the Moho depth, for a total volume of
about 1.2x10^6 km^3. This model allowed us to determine the volume of the
various geological layers and eventually integrate the Th and U contents of the
whole crust beneath LNGS. On this base the local contribution to the
geo-neutrino flux (S) was calculated and added to the contribution given by the
rest of the world, yielding a Refined Reference Model prediction for the
geo-neutrino signal in the Borexino detector at LNGS: S(U) = (28.7 \pm 3.9) TNU
and S(Th) = (7.5 \pm 1.0) TNU. An excess over the total flux of about 4 TNU was
previously obtained by Mantovani et al. (2004) who calculated, based on general
worldwide assumptions, a signal of 40.5 TNU. The considerable thickness of the
sedimentary rocks, almost predominantly represented by U- and Th- poor
carbonatic rocks in the area near LNGS, is responsible for this difference.Comment: 45 pages, 5 figures, 12 tables; accepted for publication in GC
Self-reported dental hygiene, obesity, and systemic inflammation in a pediatric rural community cohort
Background
A growing body of epidemiologic evidence links oral health, obesity, and cardiovascular health, though few studies have reported on these relationships in children. While underlying mechanisms are unclear, adult studies have suggested sub-acute systemic inflammation, also implicated in the etiology of both obesity and cardiovascular disease. This study investigated associations between self-reported dental hygiene, obesity, and systemic inflammation in children. Methods
128 children \u3c 19 years of age from rural counties in West Virginia participated in a community-based health screening that included anthropometric assessments, blood collection, and a questionnaire about dental hygiene and self-assessed oral health. Results
Participants ranged from 3.0-18.7 years. Univariate analysis demonstrated an association between parent-reported dental hygiene, including frequency of preventive dental care and parent-assessed overall dental health, and markers of systemic inflammation but not obesity. In multivariable regression, parent-assessed overall dental health and obesity were independent predictors of systemic inflammation, after adjustment for age, gender, and parent education. Conclusions
This is the first known study of the association between dental hygiene, obesity, and systemic inflammation in children. These results highlight the importance of preventive dental care in overall, systemic health in children and are consistent with previous reports in adults
Nanomechanical investigation of soft biological cell adhesion using atomic force microscopy
Mechanical coupling between living cells is a complex process that is important for a variety of biological processes. In this study the effects of specific biochemical treatment on cell-to-cell adhesion and single cell mechanics were systematically investigated using atomic force microscopy (AFM) single cell force spectroscopy. Functionalised AFM tipless cantilevers were used for attaching single suspended cells that were brought in contact with substrate cells. Cell-to-cell adhesion parameters, such as maximum unbinding force (F max) and work or energy of detachment (W D), were extracted from the retraction forceâdisplacement (Fâd) curves. AFM indentation experiments were performed by indenting single cells with a spherical microbead attached to the cantilever. Hertzian contact model was applied to determine the elastic modulus (E) of single cells. Following treatment of the cells with neutralising antibody for epithelial (E)-cadherin, F max was increased by 25%, whereas W D decreased by 11% in response to a 43% increase in E. The results suggest that although the adhesion force between cells was increased after treatment, the energy of adhesion was decreased due to the reduced displacement separation as manifested by the loss of elastic deformation. Conclusively, changes in single cell mechanics are important underlying factors contributing to cell-to-cell adhesion and hence cytomechanical characterization is critical for cell adhesion measurements
Number of teeth and myocardial infarction and stroke among elderly never smokers
<p>Abstract</p> <p>Background</p> <p>In most previous studies the association between number of teeth and cardiovascular diseases has been found to be stronger among younger age groups than in older age groups, which indicates that age may modify the association between number of teeth and cardiovascular diseases.</p> <p>We investigated the association between tooth loss and atherosclerotic vascular diseases such as myocardial infarction and stroke in a homogeneous elderly population.</p> <p>The study population was comprised of a subpopulation of 392 community-living elderly people who participated in the population-based Kuopio 75+ study. The data were collected through an interview, a structured clinical health examination and from patient records. The main outcome measures were a history of diagnosed myocardial infarction and diagnosed ischemic stroke. Prevalence proportion ratios (PPR) were estimated using generalised linear models.</p> <p>Results</p> <p>Edentate subjects had a weakly, statistically non-significantly increased likelihood of a history of myocardial infarction and ischemic stroke compared with dentate subjects. Those with a large number of teeth had a slightly, but not statistically significantly increased likelihood of a history of myocardial infarction and ischemic stroke compared with those with a small number of teeth.</p> <p>Conclusion</p> <p>These data did not show evidence that total or partial tooth loss would be associated with atherosclerotic vascular diseases such as myocardial infarction and ischemic stroke among an elderly population aged 75 years or older.</p
Broad targeting of resistance to apoptosis in cancer
Apoptosis or programmed cell death is natural way of removing aged cells from the body. Most of the anti-cancer therapies trigger apoptosis induction and related cell death networks to eliminate malignant cells. However, in cancer, de-regulated apoptotic signaling, particularly the activation of an anti-apoptotic systems, allows cancer cells to escape this program leading to uncontrolled proliferation resulting in tumor survival, therapeutic resistance and recurrence of cancer. This resistance is a complicated phenomenon that emanates from the interactions of various molecules and signaling pathways. In this comprehensive review we discuss the various factors contributing to apoptosis resistance in cancers. The key resistance targets that are discussed include (1) Bcl-2 and Mcl-1 proteins; (2) autophagy processes; (3) necrosis and necroptosis; (4) heat shock protein signaling; (5) the proteasome pathway; (6) epigenetic mechanisms; and (7) aberrant nuclear export signaling. The shortcomings of current therapeutic modalities are highlighted and a broad spectrum strategy using approaches including (a) gossypol; (b) epigallocatechin-3-gallate; (c) UMI-77 (d) triptolide and (e) selinexor that can be used to overcome cell death resistance is presented. This review provides a roadmap for the design of successful anti-cancer strategies that overcome resistance to apoptosis for better therapeutic outcome in patients with cancer
Prognosis of patients with primary central nervous system lymphoma after high-dose chemotherapy followed by autologous stem cell transplantation
- âŠ