RESUMO
Since their discovery in 2004, carbon dots (CDs) have attracted attention due to their intrinsic physicochemical properties and the easy synthesis from simple precursors. However, quantification of CDs in mixtures of nanoparticles with similar sizes and surface functionality is still a challenging issue for research applications or regulatory purposes. In this work, CDs and silver nanoparticles were first synthesized under alkaline conditions by using glucose as precursor and capping agent, respectively. Mixtures of these nanoparticles were made at micromolar range, without purification, and then analyzed by CE-DAD, using an electrolyte solution composed of 20 mM sodium borate and 20 mM SDS at pH 8.5, in a total time of <15 min. The three-way electrophoretic data were then decomposed by advanced chemometric models, parallel factor analysis and multivariate curve resolution-alternating least-squares. The explained variances for both models were 95.8% (parallel factor analysis) and 85.3% (multivariate curve resolution-alternating least-squares). In both cases, the quality of the results was verified by the root mean square standard deviation coefficient variation, which resulted lower than 5%, and no significant bias was observed at 95% of statistical confidence. Satisfactory prediction for CDs concentration was obtained with recovery values between 80.0% and 115%.
Assuntos
Carbono , Nanopartículas Metálicas , Carbono/química , Quimiometria , Eletroforese Capilar/métodos , PrataRESUMO
Between November 2019 and February 2020, 53 water samples were collected along 430 km of coastline in northeastern Brazil, which was the location of an oil spill that occurred in August 2019. Synchronous fluorescence matrices (SFMs) were acquired to avoid regions affected by Raman Stokes scatterings and second harmonic signals, and then, the SFMs were converted into excitation-emission matrices (EEM) by shear transformation. The matrix coupled with parallel factor analysis (PARAFAC) was used in the study of fluorescent components present in the collected waters. A sample collected before the oil spill and another from Florianópolis-SC, 2000 km from the incident, were used as references for nonimpacted waters. In the postspill samples, 4 components were determined, with component 1 (λexc = 225 nm, λem = 475 nm) being associated with humic-like organic matter (terrestrial), component 2 (λexc = 230 nm, λem = 390 nm) being associated with humic-like organic matter (marine), component 3 (λexc = 225/295 nm, λem = 345 nm) being associated with dibenzothiophene-like components also observed in tests with crude oil samples, and component 4 (λexc = 220/280 nm, λem = 340 nm) being associated with a naphthalene-like substance. Principal component analysis (PCA) was performed on the PARAFAC scores. The distribution of samples along the 4 components was observed and compared with the reference samples.
Assuntos
Poluição por Petróleo , Poluentes Químicos da Água , Brasil , Análise Fatorial , Substâncias Húmicas/análise , Poluição por Petróleo/análise , Espectrometria de Fluorescência , Poluentes Químicos da Água/análiseRESUMO
Background: Cervical spondylomyelopathy (CSM) is a common disease of the cervical spine, and causes neurogenic disorders commonly diagnosed in large and giant breeds dogs. There are many surgical procedures proposed for the treatment of CSM. Although many authors report a high success rate (between 70% and 90%) after surgical procedures, the high number of techniques described reflects the difficulty in treating this disorder. The objective of this paper is to report a case of CSM with chronic ventral compression (intervertebral disc extrusion) that was treated with dorsal decompression, and to demonstrate the effectiveness of the decompressive technique through pre- and post-operative myelograms. Case: A 9-year-old Doberman Pinscher dog weighing 41.8 kg presented due to a history of tetraparesis. Neurological examination did not reveal any alteration in mental status. There was absence of conscious proprioception on the four limbs; the pelvic limbs were more severely affected. Bilateral patellar hyperreflexia and normal flexor withdrawal reflex were observed on the hind limbs. There was decreased flexor withdrawal reflex and increased extensor tone on the forelimbs. The patient exhibited pain during caudal cervical palpation, and no alterations were seen on the cutaneous trunci reflex. Superficial pain was absent in the hind limbs; forelimbs exhibited presence of motor [...](AU)
Assuntos
Animais , Cães , Laminectomia/veterinária , Espondilose/veterinária , Doenças da Medula Espinal/veterinária , Cauda/lesões , Mielografia/veterinária , Descompressão Cirúrgica/veterináriaRESUMO
Background: Cervical spondylomyelopathy (CSM) is a common disease of the cervical spine, and causes neurogenic disorders commonly diagnosed in large and giant breeds dogs. There are many surgical procedures proposed for the treatment of CSM. Although many authors report a high success rate (between 70% and 90%) after surgical procedures, the high number of techniques described reflects the difficulty in treating this disorder. The objective of this paper is to report a case of CSM with chronic ventral compression (intervertebral disc extrusion) that was treated with dorsal decompression, and to demonstrate the effectiveness of the decompressive technique through pre- and post-operative myelograms. Case: A 9-year-old Doberman Pinscher dog weighing 41.8 kg presented due to a history of tetraparesis. Neurological examination did not reveal any alteration in mental status. There was absence of conscious proprioception on the four limbs; the pelvic limbs were more severely affected. Bilateral patellar hyperreflexia and normal flexor withdrawal reflex were observed on the hind limbs. There was decreased flexor withdrawal reflex and increased extensor tone on the forelimbs. The patient exhibited pain during caudal cervical palpation, and no alterations were seen on the cutaneous trunci reflex. Superficial pain was absent in the hind limbs; forelimbs exhibited presence of motor [...]