Search results for "Molar"

The use of spiral CT in the detection and management of a permanent maxillary first molar with single root and single canal : a rare occurrence

2017

A sound knowledge of the normal tooth morphology and its numerous variations is essential to the success of endodontic therapy. While extra canals and lateral canals are routinely encountered and documented, there also exists the rare possibility of a fewer number of canals than normal. Early detection of such an occurrence is critical to the prevention of iatrogenic errors during endodontic treatment. The advent of spiral CT as a diagnostic tool serves as a much needed confirmation to understand the complex three dimensional anatomy of teeth. The aim of this case report is to highlight one such case reporting unusual morphology of the permanent maxillary first molar displaying single canal…

Dental anatomy portrayed with microscopic volume investigations

1993

The clinical treatment of the root canal of teeth--called endodontics--assumes a precise idea of the spatial arrangement of the anatomy of teeth and their inner structure. By using computer-assisted data acquisition from filmed sequences of histologic serial sections and a special kind of magnetic resonance microscope--the Stray Field Imaging (STRAFI)--volume investigations were carried out using special functions of a newly developed 3D software. Possible applications and future perspectives are discussed.

Monitoring WWTP performance using size-exclusion chromatography with simultaneous UV and fluorescence detection to track recalcitrant wastewater frac…

2018

Abstract A trial monitoring of a typical full-scale municipal WWTP in Central Finland was aimed to explore applicability of high performance liquid chromatography – size exclusion chromatography (HPSEC) with simultaneous UV and fluorescence detection as a tool for advanced routine monitoring of wastewater treatment. High, intermediate, and low molecular weight (MW) fractions of untreated wastewater (influent) and treated wastewater (secondary effluent) were characterized in terms of UV absorbance at 254 nm (UVA254) and specific fluorescence representing tyrosine-like, tryptophan-like, and humic/fulvic-like compounds. The activated sludge treatment removed 97 ± 1% of BOD, 93 ± 2% of COD, 71 …

2018

Reactivity is an important parameter when considering the chemical modification or dissolution of cellulose. Different pretreatment methods affect cellulose reactivity by decreasing its degree of polymerization (DP) and crystallinity. In this study, the molar mass of cellulose was decreased via enzymatic pretreatment. Three commercial endoglucanase-rich products were tested. The target was to reduce the viscosity of the pulp to below 200 mL/g and, thus, increase the reactivity of the cellulose. For comparison, cellulose was also pretreated with ozone, and the effects of each pretreatment method on crystallinity and monosaccharide composition of the resulting pulps were investigated. Both en…

Convenient Access to α‐Amino‐ω‐Hydroxyl Heterobifunctional PEG and PPO via a Sacrificial Hexahydro‐Triazine Star Strategy

2019

The anionic ring opening polymerizations of ethylene oxide (EO) and propylene oxide (PO) are performed by using 1,3,5-triethanol hexahydro-1,3,5-triazine (TrAz) as a "sacrificial" trifunctional initiator. Well-defined three-arm star polymers are obtained with a narrow molecular weight distribution (M w /M n < 1.1). Molecular weights range from 3-15 kg mol-1 . Since these star polymers possess an acid-labile hexahydro-triazine core, acidic hydrolysis leads to cleavage of the arms. This gives access to well-defined α-amino-ω-hydroxyl heterobifunctional poly(ethylene glycol) (PEG) and poly(propylene oxide) (PPO) in the molecular weight range of 1-5 kg mol-1 and low dispersity M w /M n < 1.1. T…

Characterization of ethylene oxide/tert-octylphenol condensates by ultraviolet and infrared spectrometry

1986

Abstract The average degree of condensation of ethylene oxide/tert-octylphenol condensate surfactants can be estimated rapidly by u.v. and i.r. spectrometry. The u.v. method is based on evaluating the specific absorptivity, a , at 275 nm in aqueous ethanol (60:40 v/v), and inserting this value in equations obtained from previously characterized samples, relating a to the average properties to be determined. Infrared spectrometry is applied similarly; the average properties to be determined are related to the ratio between the band heights at 960 and 840 cm −1 . The relative standard deviations ( n = 10) obtained for a sample of Triton X-100 were 2% by u.v. spectrometry, and 3% by i.r. spect…

Secondary structure of peptides. 4:13C-Nmr CP/MAS investigation of solid oligo- and poly(L-alanines)

1983

Primary and tertiary amine-initiated polymerizations of L-alanine-N-carboxyanhydride (L-Ala-NCA) were conducted at 20 or 100°C in a variety of solvents. The 75.5-MHz 13C-nmr CP/MAS spectra of the resulting poly(L-alanines) revealed that all samples contain both α-helix and pleated-sheet structures. Depending on the reaction conditions the α-helix content varied between ca. 1 and 99%. Reprecipitation from aprotic nonsolvents does not change the α-helix/β-sheet ratio, indicating that this ratio is thermodynamically controlled. Since relatively large amounts of oligopeptides of degree of polymerization (DP) 4–6 can be extracted by means of acetic acid, it is concluded that (a) most poly(L-alan…

The role of crystalline, mobile amorphous and rigid amorphous fractions in the performance of recycled poly (ethylene terephthalate) (PET)

2012

[EN] The action of thermo-mechanical degradation induced by mechanical recycling of poly(ethylene terephthalate) was simulated by successive injection moulding cycles. Degradation reactions provoked chain scissions and a reduction in molar mass mainly driven by the reduction of diethyleneglycol to ethylene glycol units in the flexible domain of the PET backbone, and the formation of -OH terminated species with shorter chain length. The consequent microstructural changes were quantified taking into account a three-fraction model involving crystalline, mobile amorphous (MAF) and rigid amorphous fractions (RAF). A remarkable increase of RAF, to a detriment of MAF was observed, while the percen…

Sulfur-free pulping of hot-water-extracted spruce sawdust

2016

Softwood (Picea abies) sawdust was hot-water-extracted with two multi-phase processes (160-180°C, 100-280 min, and liquor-to-wood ratio 5 l/kg) corresponding to P-factors of ~780 (yield 80.0%) and ~4580 (yield 72.4%). The pre-treated materials were then pulped with the soda-AQ cooking (170°C, NaOH charge 20%, AQ charge 0.1%, 30-150 min, and liquor-to-wood ratio 5 l/kg), resulting in a yield range of 36.1-61.4% (for reference cooks without pre-extraction 47.9-60.0%). It was observed that the pre-extraction under moderate conditions enhanced the dissolution especially of large-molar-mass lignin during cooking, and the total amount of the dissolved lignin was also higher than that removed from…

Shape transitions of giant liposomes induced by an anisotropic spontaneous curvature

2000

International audience; We explore how a magnetic field breaks the symmetry of an initially spherical giant liposome filled with a magnetic colloid. The condition of rotational symmetry along the field axis leads either to a prolate or to an oblate ellipsoid. We demonstrate that an electrostatic interaction between the nanoparticles and the membrane triggers the shape transition. PACS numbers: 75.