ABSTRACT
A stereoselective [3+2] cycloaddition approach to functionalized pentaquinanes starting from cis-syn-cis triquinanes, derived from Cookson's diones, is reported. This transformation involves generation of six new stereocenters in a single step leading to cis-anti-cis-syn-cis-anti-cis polyquinane systems. Our method prevents transannular cyclizations which are prevalent in these moieties. The structure and stereochemistry of target molecules are well-characterized based on NMR data and X-ray diffraction studies.
Subject(s)
Alkenes , Silanes , Alkenes/chemistry , Cyclization , Molecular Structure , Silanes/chemistryABSTRACT
We report an efficient synthetic strategy to diverse hydantoins and thiohydantoins involving a three-component reaction with the aid of deep eutectic solvent. Here, N,N'-dimethyl urea and N,N'-dimethyl thiourea play a dual role as reactant and reaction medium along with l-(+)-tartaric acid. The three-component reaction provides an easy access to 5-amino-1,3-dialkyl-substituted hydantoins and thiohydantoins in good yields.
ABSTRACT
INTRODUCTION: Irrigating solutions are used for cleaning and removing dentinal debris, and the other remains from pulpal space during biomechanical preparation. Therefore, we evaluated the impact of various irrigating agents on root fracture at 5-minute time exposure. MATERIALS AND METHODS: We sectioned 60 permanent maxillary premolars with fully formed root structures transversely maintaining the root length of approximately 14 mm. Five study groups were made comprising ethylenediaminetetraacetic acid (EDTA), cetrimide, citric acid, and so on as various irrigating agents. A universal force test machine was used to calculate the force which was enough to fracture each root. Analysis of variance (ANOVA) test was used to access the level of significance. RESULTS: About 10% citric acid solution as an irrigating agent showed minimal fracture opposing results, whereas 10% EDTA solution showed the maximum fracture resistance of root portion. CLINICAL SIGNIFICANCE: Selection of suitable EDTA concentration that has minimal adverse effect on the mechanical properties of the tooth is very important for the successful management of tooth fracture. CONCLUSION: About 10% EDTA provided the highest fracture resistance, necessitating the use of irrigating solution in root canal therapy (RCT). Further research with higher and different study groups is required to search for more efficient irrigating solution to improve the outcome of RCT.
Subject(s)
Root Canal Irrigants , Tooth Fractures/prevention & control , Tooth Root/injuries , Cetrimonium , Cetrimonium Compounds , Citric Acid , Dental Stress Analysis , Doxycycline , Edetic Acid , Humans , Materials Testing , Root Canal PreparationABSTRACT
This paper reports the investigation of a micro-gas chromatography (µGC) system that utilizes an array of miniaturized motionless Knudsen pumps (KPs) as well as microfabricated separation columns and optical detectors. A prototype system was built to achieve a flow rate of 1 mL min(-1) and 0.26 mL min(-1) for helium and dry air, respectively, when they were used as carrier gas. This system was then employed to evaluate GC performance compromises and demonstrate the ability to separate and detect gas mixtures containing analytes of different volatilities and polarities. Furthermore, the use of pressure programming of the KP array was demonstrated to significantly shorten the analysis time while maintaining a high detection resolution. Using this method, we obtained a high resolution detection of 5 alkanes of different volatilities within 5 min. Finally, we successfully detected gas mixtures of various polarities using a tandem-column µGC configuration by installing two on-column optical detectors to obtain complementary chromatograms.
Subject(s)
Chromatography, Gas/instrumentation , Microtechnology/instrumentation , Optical Phenomena , Volatile Organic Compounds/chemistryABSTRACT
Many cases of progressive heart failure due to cardiac amyloidosis remain undiagnosed due to the rarity and lack of suspicion on part of physician. Treatment options are limited and patients are also poor responders in later stages. Hence, early diagnosis by recognition of syndromic presentation and diagnostic modalities is helpful in retarding the disease process.
Subject(s)
Amyloidosis/pathology , Heart Failure/etiology , Adult , Amyloidosis/complications , Biopsy , Diagnosis, Differential , Echocardiography, Doppler, Color , Electrocardiography , Endoscopes , Female , Humans , Male , Middle AgedABSTRACT
Diagnosis of acute myocardial infarction (AMI) has to be made early in the emergency triage since maximal mortality occurs within first hour and the benefits of all interventions are greater once these are instituted early. Diagnosis is easy and based on simple principals of good history, physical examination, early and complete 12 lead electrocardiogram and use of echocardiography which should be available in the emergency triage area. Subsequently biomarkers are also available for documentation and risk stratification. The other causes of acute severe chest pain should be kept in mind and ruled out. The role of myocardial perfusion imaging for diagnosis of AMI is limited. The diagnosis also involves an estimation of the size of infarct, duration since onset of the process, any acute complications of AMI and the likely vessel involved since these have significant therapeutic implications.
