167 research outputs found
Automatic interpretation of MSS-LANDSAT data applied to coal refuse site studies in southern Santa Catarina State, Brazil
The coal mining district in southeastern Santa Catarina State is considered one of the most polluted areas of Brazil. The author has identified significant preliminary results on the application of MSS-LANDSAT digital data to monitor the coal refuse areas and its environmental consequences in this region
Elution study of acrylic monomers from orthodontic materials using high performance liquid chromatography (HPLC)
Purpose: Main goal of the study was the identification and quantitative analysis of monomer elution from materials commonly used in fixed orthodontic therapy. Studies have shown severe health effects of monomers including cytotoxic, allergenic or mutagenic potential and endocrine changes. This in vitro study focusses primarily on five resins which are usually processed intraorally and remain in the oral cavity long-term.
Methods: We tested the elution of monomers from specimens (7.5 mm x 1.5 mm) immersed in artificial saliva at body temperature (37 degrees C) for 30 min to 5 weeks. The used method is in accordance with DIN EN ISO 10993-13. The five tested materials were BrackFix (R) (Voco GmbH, Cuxhaven, Germany), Triad (R) Gel (DeguDent GmbH, Hanau, Germany), and Transbond (TM) XT, LR and Plus (3M Unitek, Monrovia, CA, USA). All aliquots were analyzed using high performance liquid chromatography (HPLC). Data were statistically analyzed.
Results: All five analyzed materials eluted substances over a period of 5 weeks. Identified substances included bisphenol A (BPA), triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA). BPA eluted from Transbond (TM) Plus, XT, LR and BrackFix (R). The cumulated mean values after 35 days ranged from 16.04 to 64.83 ppm, depending on the material. TEGDMA eluted with a mean of 688.61 ppm from Transbond (TM) LR. UDMA with a mean of 1682.00 ppm from Triad (R) Gel. For each material the highest concentrations of all these substances were found in the first elution period. Other substances that were not equivocally identified or of low concentration also eluted.
Conclusion: Using the described method, it is possible to qualitatively and quantitatively determine the in vitro elution of monomers from orthodontic materials. The concentrations of the substances identified were below the current maximum recommended intake. However, a cumulative effect and low-dose effects should be considered for both patients and dental professionals, especially for young patients. Measures to reduce exposure patients and practitioners are suggested
Modification of hyperacute canine renal homograft and pig-to-dog heterograft rejection by the intra-arterial infusion of citrate
Hyperacute rejection was studied in seven presensitized canine recipients of renal homografts and in 22 canine recipients of pig kidneys. Under both experimental circumstances, untreated animals rejected the grafts within a few minutes. With the intra-arterial infusion of sodium citrate, hyperacute heterograft rejection was forestalled for the duration of therapy, and with homografts the benefit outlasted treatment by many hours. The protection of heterografts was not due solely to anticoagulation by the citrate, since heparin in large doses did not accomplish the same thing. A contributory factor may have been complement inhibition since removal of complement by the grafts was greatly reduced in the citrate-treated animals. © 1971
Shape dynamics and migration of branched cells on complex networks
Migratory and tissue resident cells exhibit highly branched morphologies to
perform their function and to adapt to the microenvironment. Immune cells, for
example, display transient branched shapes while exploring the surrounding
tissues. In another example, to properly irrigate the tissues, blood vessels
bifurcate thereby forcing the branching of cells moving on top or within the
vessels. In both cases microenvironmental constraints force migrating cells to
extend several highly dynamic protrusions. Here, we present a theoretical model
for the shape dynamics and migration of cells that simultaneously span several
junctions, which we validated by using micropatterns with an hexagonal array,
and a neuronal network image analysis pipeline to monitor the macrophages and
endothelial cell shapes and migration. In our model we describe how the actin
retrograde flow controls branch extension, retraction and global cell
polarization. We relate the noise in this flow to the residency times and
trapping of the cell at the junctions of the network. In addition, we found
that macrophages and endothelial cells display very different migration regimes
on the network, with macrophages moving faster and having larger changes in
cell length in comparison to endothelial cells. These results expose how
cellular shapes and migration are intricately coupled inside complex
geometries
An automatic agricultural zone classification procedure for crop inventory satellite images
A classification procedure for assessing crop areal proportion in multispectral scanner image is discussed. The procedure is into four parts: labeling; classification; proportion estimation; and evaluation. The procedure also has the following characteristics: multitemporal classification; the need for a minimum field information; and verification capability between automatic classification and analyst labeling. The processing steps and the main algorithms involved are discussed. An outlook on the future of this technology is also presented
Mapping of land use and geomorphology in the APAPORE project area by LANDSAT satellite data, volume 1
The results of a land use and geomorphological mapping of the so-called Projeto APAPORE area, at Mato Grosso do Sul State are presented. The study was carried out using multispectral scanner (MSS) and return beam vidicon LANDSAT images (channels 5 and 7 for the MSS) at the scale of 1:250,000 from 1980 through visual interpretation. The results indicate that pastureland is the most widespead class and that the agricultural areas re concentrated in the north of the area under study. The area covered with cerradao (arboreous savanna type) has a great areal extention, thus permitting the advance of the agricultural frontier. The geomorphological mapping can be useful to regional planning of future land use within the studied area
Co-Oligomers of Renewable and "Inert" 2-MeTHF and Propylene Oxide for Use in Bio-Based Adhesives
Commercial polyether polyols are usually obtained by the ring-opening polymerization of epoxides or tetrahydrofuran. 2-Methyl-tetrahydrofuran (2-MeTHF) could be an alternative bio-based building block for the synthesis of these polyols. Although 2-MeTHF cannot be polymerized, we did achieve the copolymerization of 2-MeTHF with propylene oxide (PO) using Lewis and Brønsted acids as catalysts and water or diols as initiators. The resulting polyether polyols have a molecular weight range, which allows their use as components for adhesives. The molar content of 2-MeTHF in the oligomers can be up to 48%. A 1:1 copolymer of 2-MeTHF and PO is produced when stoichiometric amounts of BF3·OEt2 are used. Here, the monomeric units in the chains alternate, but also cyclic or other nondiol products are formed that are detrimental to its further use in adhesives. Linear dihydroxyl-terminated polyether chains were formed when the heteropolyacid H3PW12O40·24H2O was used as a catalyst and a diol as an initiator. The formation of cyclic products can be drastically reduced when the accumulation of propylene oxide during the reaction is avoided. 1H NMR experiments indicate that the step of 2-MeTHF incorporation is the alkylation of 2-MeTHF by protonated PO. It was shown that the 2-MeTHF/PO copolymer had increased tensile strength compared to polypropylene glycol in a two-component adhesive formulation
Insights into Electrolytic Pre Lithiation A Thorough Analysis Using Silicon Thin Film Anodes
Pre lithiation via electrolysis, herein defined as electrolytic pre lithiation, using cost efficient electrolytes based on lithium chloride LiCl , is successfully demonstrated as a proof of concept for enabling lithium ion battery full cells with high silicon content negative electrodes. An electrolyte for pre lithiation based on amp; 947; butyrolactone and LiCl is optimized using boron containing additives lithium bis oxalato borate, lithium difluoro oxalate borate and CO2 with respect to the formation of a protective solid electrolyte interphase SEI on silicon thin films as model electrodes. Reversible lithiation in Si Li metal cells is demonstrated with Coulombic efficiencies CEff of 95 96 for optimized electrolytes comparable to 1 m LiPF6 EC EMC 3 7. Formation of an effective SEI is shown by cyclic voltammetry and X ray photoelectron spectroscopy XPS . electrolytic pre lithiation experiments show that notable amounts of the gaseous product Cl2 dissolve in the electrolyte leading to a self discharge Cl2 Cl amp; 8722; shuttle mechanism between the electrodes lowering pre lithiation efficiency and causing current collector corrosion. However, no significant degradation of the Si active material and the SEI due to contact with elemental chlorine is found by SEM, impedance, and XPS. In NCM111 Si full cells, the capacity retention in the 100th cycle can be significantly increased from 54 to 78 by electrolytic pre lithiation, compared to reference cells without pre lithiation of S
Excision of sympathetic ganglia and the rami communicantes with histological confirmation offers better early and late outcomes in Video assisted thoracoscopic sympathectomy
<p>Abstract</p> <p>Background</p> <p>Video-Assisted Thoracoscopic Sympathectomy (VATS) is an established minimally invasive procedure for thoracic sympathetic blockade in patients with hyperhidrosis, facial flushing and intractable angina. Various techniques using clips, diathermy and excision are used to perform sympathectomy. We present our technique of excision of the sympathetic chain with histological proof and the analysis of the early and late outcomes.</p> <p>Methods</p> <p>We evaluated 200 procedures in 100 consecutive patients, who underwent Video Assisted Thoracoscopic Sympathectomy by a single surgeon in our centre between September 1996 to March 2007. All patients had maximum medical therapy prior to surgery and were divided into 3 groups based on indications, Group 1(hyperhidrosis: 48 patients), Group 2 (facial flushing: 26 patients) and Group 3(intractable angina: 26 patients). The demography and severity of symptoms for each group were analysed. The endpoints were success rate, 30 day mortality, complications and patient's satisfaction.</p> <p>Results</p> <p>99 patients had bilateral VATS sympathectomy and 1 had unilateral sympathectomy. The conversion rate to open was 1(1%). All patients had successful removal of ganglia proven histologically with no perioperative mortality in our series. The complications included pneumothorax (5%), acute coronary syndrome (2%), transient Horner's syndrome (1%), transient paraesthesia (1%), wound infection (4%), compensatory hyperhidrosis (18%), residual flushing (3%) and wound pain (5%). There were five late deaths in the intractable angina group at a mean follow up of 36.7 months. Overall success rates of abolishing the symptoms were 96.3%, 87.5% and 95.2% for Group 1, 2 and 3 respectively.</p> <p>Conclusion</p> <p>Excision of the sympathetic chain with histological confirmation during VATS sympathectomy is a safe and effective method in treating hyperhidrosis, facial flushing and intractable angina with good long term results and satisfaction.</p
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