RESUMO

The first hyperpolarizability of graphene quantum dots (GQDs) suspended in water was determined using the hyper-Rayleigh scattering (HRS) technique. To the best of our knowledge, this is the first application of the HRS technique to characterize GQDs. Two commercial GQDs (Acqua-Cyan and Acqua-Green) with different compositions were studied. The HRS experiments were performed with an excitation laser at 1064 nm. The measured hyperpolarizabilities were (1.0±0.1)×10-27 esu and (0.9±0.1)×10-27 esu for Acqua-Cyan and Acqua-Green, respectively. The results were used to estimate the hyperpolarizability per nanosheet obtained by assuming that each GQD has five nanosheets with 0.3 nm thickness. The two-level model, used to calculate the static hyperpolarizability per nanosheet, provides values of (2.4±0.1)×10-28 esu (Acqua-Cyan) and (0.5±0.1)×10-28 esu (Aqua-Green). The origin of the nonlinearity is discussed on the basis of polarized resolved HRS experiments, and electric quadrupolar behavior with a strong dependence on surface effects. The nontoxic characteristics and order of magnitude indicate that these GQDs may be useful for biological microscopy imaging.

RESUMO

There is already a societal awareness of the growing impact of nanoscience and nanotechnology, with nanomaterials (with at least one dimension less than 100 nm) now incorporated in items as diverse as mobile phones, clothes or dentifrices. In the healthcare area, nanoparticles of biocompatible materials have already been used for cancer treatment or bioimaging enhancement. Nanotechnology in dentistry, or nanodentistry, has already found some developments in dental nanomaterials for caries management, restorative dentistry and orthodontic adhesives. In this review, we present state-of-the-art scientific development in nanodentistry with an emphasis on two imaging techniques exploiting nanomaterials: optical coherence tomography (OCT) and photoacoustic imaging (PAI). Examples will be given using OCT with nanomaterials to enhance the acquired imaging, acting as optical clearing agents for OCT. A novel application of gold nanoparticles and nanorods for imaging enhancement of incipient occlusal caries using OCT will be described. Additionally, we will highlight how the OCT technique can be properly managed to provide imaging with spatial resolution down to 10's-100's nm resolution. For PAI, we will describe how new nanoparticles, namely TiN, prepared by femtosecond laser ablation, can be used in nanodentistry and will show photoacoustic microscopy and tomography images for such exogenous agents.

RESUMO

Nonlinear optical characterization of nanostructured layered transition metal dichalcogenides (LTMDs) is of fundamental interest for basic knowledge and applied purposes. In particular, second-order optical nonlinearities are the basis for second harmonic generation as well as sum or difference frequency generation and have been studied in some 2D TMDs, especially in those with a semiconducting character. Here we report, for the first time, on the second-order nonlinearity of the semi-metallic ZrTe2 monolayer in acetonitrile suspension (concentration of 4.9 × 1010 particles per cm3), synthesized via a modified redox exfoliation method and characterized using the Hyper-Rayleigh scattering technique in the nanosecond regime. The orientation-averaged first-hyperpolarizability was found to be ß(2ω) = (7.0 ± 0.3) × 10-24 esu per ZrTe2 monolayer flake, the largest reported so far. Polarization-resolved measurements were performed in the monolayer suspension and indicate the dipolar origin of the generated incoherent second harmonic wave.

RESUMO

Background: Myelomalacia is a multifocal syndrome that causes hemorrhagic infarction of the spinal cord that can occur as a sequel to acute spinal cord injury. It occurs as a consequence of acute spinal cord trauma, usually by extrusion of intervertebral disc in the thoracolumbar spine, affecting up to 10% of dogs with acute paralysis and deep pain loss in the pelvic limbs due to disc disease. This disease may be focal or diffuse; the diffuse form is typically associated with cranial and caudal migration of neurologic signs and is often fatal. The mechanical lesion to the spinal cord triggers secondary injury mediated by the existence of oxygen free radicals, alterations in the concentrations of neurotransmitters ions and amino acids, and it results in the reduction of the spinal cord blood fl ow, ischemia and progressive cranial and caudal necrosis to the focus of the initial injury.Case: A 5-year-old Dachshund male intact dog weighting 8 kg was referred to the Veterinary Teaching Hospital of the Federal University of Rio Grande do Sul (HCV-UFRGS) with initial complaint of acute paralysis of the hind limbs for two days. On clinical examination there was paraplegia, absence of deep pain in the pelvic limbs, with decreased patellar, sciatic and tibial cranial refl exes. The anal sphincter was relaxed and the bladder was easily expressed. The panniculus refl ex was intact up to t

Background: Myelomalacia is a multifocal syndrome that causes hemorrhagic infarction of the spinal cord that can occur as a sequel to acute spinal cord injury. It occurs as a consequence of acute spinal cord trauma, usually by extrusion of intervertebral disc in the thoracolumbar spine, affecting up to 10% of dogs with acute paralysis and deep pain loss in the pelvic limbs due to disc disease. This disease may be focal or diffuse; the diffuse form is typically associated with cranial and caudal migration of neurologic signs and is often fatal. The mechanical lesion to the spinal cord triggers secondary injury mediated by the existence of oxygen free radicals, alterations in the concentrations of neurotransmitters ions and amino acids, and it results in the reduction of the spinal cord blood fl ow, ischemia and progressive cranial and caudal necrosis to the focus of the initial injury.Case: A 5-year-old Dachshund male intact dog weighting 8 kg was referred to the Veterinary Teaching Hospital of the Federal University of Rio Grande do Sul (HCV-UFRGS) with initial complaint of acute paralysis of the hind limbs for two days. On clinical examination there was paraplegia, absence of deep pain in the pelvic limbs, with decreased patellar, sciatic and tibial cranial refl exes. The anal sphincter was relaxed and the bladder was easily expressed. The panniculus refl ex was intact up to t

RESUMO

Background: Myelomalacia is a multifocal syndrome that causes hemorrhagic infarction of the spinal cord that can occur as a sequel to acute spinal cord injury. It occurs as a consequence of acute spinal cord trauma, usually by extrusion of intervertebral disc in the thoracolumbar spine, affecting up to 10% of dogs with acute paralysis and deep pain loss in the pelvic limbs due to disc disease. This disease may be focal or diffuse; the diffuse form is typically associated with cranial and caudal migration of neurologic signs and is often fatal. The mechanical lesion to the spinal cord triggers secondary injury mediated by the existence of oxygen free radicals, alterations in the concentrations of neurotransmitters ions and amino acids, and it results in the reduction of the spinal cord blood fl ow, ischemia and progressive cranial and caudal necrosis to the focus of the initial injury.Case: A 5-year-old Dachshund male intact dog weighting 8 kg was referred to the Veterinary Teaching Hospital of the Federal University of Rio Grande do Sul (HCV-UFRGS) with initial complaint of acute paralysis of the hind limbs for two days. On clinical examination there was paraplegia, absence of deep pain in the pelvic limbs, with decreased patellar, sciatic and tibial cranial refl exes. The anal sphincter was relaxed and the bladder was easily expressed. The panniculus refl ex was intact up to t

Background: Myelomalacia is a multifocal syndrome that causes hemorrhagic infarction of the spinal cord that can occur as a sequel to acute spinal cord injury. It occurs as a consequence of acute spinal cord trauma, usually by extrusion of intervertebral disc in the thoracolumbar spine, affecting up to 10% of dogs with acute paralysis and deep pain loss in the pelvic limbs due to disc disease. This disease may be focal or diffuse; the diffuse form is typically associated with cranial and caudal migration of neurologic signs and is often fatal. The mechanical lesion to the spinal cord triggers secondary injury mediated by the existence of oxygen free radicals, alterations in the concentrations of neurotransmitters ions and amino acids, and it results in the reduction of the spinal cord blood fl ow, ischemia and progressive cranial and caudal necrosis to the focus of the initial injury.Case: A 5-year-old Dachshund male intact dog weighting 8 kg was referred to the Veterinary Teaching Hospital of the Federal University of Rio Grande do Sul (HCV-UFRGS) with initial complaint of acute paralysis of the hind limbs for two days. On clinical examination there was paraplegia, absence of deep pain in the pelvic limbs, with decreased patellar, sciatic and tibial cranial refl exes. The anal sphincter was relaxed and the bladder was easily expressed. The panniculus refl ex was intact up to t

RESUMO

Background: The use of animals in attempt to understand biological processes began many years ago with Hippocrates (450 B.C.). Galeno (129-210 a.C.) studied the anatomy and physiology of the monkeys, believing in their similarity to humans. The use of animals in experiments has always been the target of too much criticism by several society segments, questioning animal suffering after manipulation. This is due to the fact that students and professors consider that such practices are against their moral and ethical principles, besides the psychological issues that they can promote. Because of this, alternative and complementary methods were developed for surgical training and motor development of surgeons, with the goal to reduce the number of animals in these practices and to increase qualifi cation and surgical skills. The objective of this study is to offer a complementary method of learning in the area of surgery, specifi cally anatomical techniques as a complementary method for learning nephrotomy.Materials, Methods & Results: Four dog kidneys were used from the pathology sector of the Universidade Federal do Rio Grande do Sul. The kidneys were removed from the abdominal cavity with the perirenal fat, blood vessels and ureter. The renal artery, renal vein and ureter were cannulated and fi lled with red, blue and yellow colored latex, respectively. After this, the kidney

Background: The use of animals in attempt to understand biological processes began many years ago with Hippocrates (450 B.C.). Galeno (129-210 a.C.) studied the anatomy and physiology of the monkeys, believing in their similarity to humans. The use of animals in experiments has always been the target of too much criticism by several society segments, questioning animal suffering after manipulation. This is due to the fact that students and professors consider that such practices are against their moral and ethical principles, besides the psychological issues that they can promote. Because of this, alternative and complementary methods were developed for surgical training and motor development of surgeons, with the goal to reduce the number of animals in these practices and to increase qualifi cation and surgical skills. The objective of this study is to offer a complementary method of learning in the area of surgery, specifi cally anatomical techniques as a complementary method for learning nephrotomy.Materials, Methods & Results: Four dog kidneys were used from the pathology sector of the Universidade Federal do Rio Grande do Sul. The kidneys were removed from the abdominal cavity with the perirenal fat, blood vessels and ureter. The renal artery, renal vein and ureter were cannulated and fi lled with red, blue and yellow colored latex, respectively. After this, the kidney

RESUMO

Background: The use of animals in attempt to understand biological processes began many years ago with Hippocrates (450 B.C.). Galeno (129-210 a.C.) studied the anatomy and physiology of the monkeys, believing in their similarity to humans. The use of animals in experiments has always been the target of too much criticism by several society segments, questioning animal suffering after manipulation. This is due to the fact that students and professors consider that such practices are against their moral and ethical principles, besides the psychological issues that they can promote. Because of this, alternative and complementary methods were developed for surgical training and motor development of surgeons, with the goal to reduce the number of animals in these practices and to increase qualifi cation and surgical skills. The objective of this study is to offer a complementary method of learning in the area of surgery, specifi cally anatomical techniques as a complementary method for learning nephrotomy.Materials, Methods & Results: Four dog kidneys were used from the pathology sector of the Universidade Federal do Rio Grande do Sul. The kidneys were removed from the abdominal cavity with the perirenal fat, blood vessels and ureter. The renal artery, renal vein and ureter were cannulated and fi lled with red, blue and yellow colored latex, respectively. After this, the kidney

Background: The use of animals in attempt to understand biological processes began many years ago with Hippocrates (450 B.C.). Galeno (129-210 a.C.) studied the anatomy and physiology of the monkeys, believing in their similarity to humans. The use of animals in experiments has always been the target of too much criticism by several society segments, questioning animal suffering after manipulation. This is due to the fact that students and professors consider that such practices are against their moral and ethical principles, besides the psychological issues that they can promote. Because of this, alternative and complementary methods were developed for surgical training and motor development of surgeons, with the goal to reduce the number of animals in these practices and to increase qualifi cation and surgical skills. The objective of this study is to offer a complementary method of learning in the area of surgery, specifi cally anatomical techniques as a complementary method for learning nephrotomy.Materials, Methods & Results: Four dog kidneys were used from the pathology sector of the Universidade Federal do Rio Grande do Sul. The kidneys were removed from the abdominal cavity with the perirenal fat, blood vessels and ureter. The renal artery, renal vein and ureter were cannulated and fi lled with red, blue and yellow colored latex, respectively. After this, the kidney

RESUMO

Among the surgical problems in birds, the fractures are the most prevalent. Due to variations in size, weight, peculiar bone anatomy, high incidence of complicated fractures and functional demands of different species and individuals, it is still not possible to establish an ideal method for osteosynthesis of long bones in birds. Titanium microplates commonly used in human maxillofacial surgery have been recently employed in osteosynthesis of birds, but with few results available. The aim of this study was to evaluate the use of titanium microplates in the treatment of tibiotarsus fractures in 30 pigeons (Columba livia) , adult males and females, with 7 months old, weighing from 400 to 500. The animals were divided into 3 groups with ten animals each. In group 1, a titanium microplate with 6 holes and a central spacer was used; in group 2, a titanium microplate with 8 holes without a spacer in the center was used; in group 3, a titanium microplate with 8 holes with central spacer was used. After clinical evaluation, the birds were submitted to mid-diaphyseal osteotomy in the right bone for placement of different configurations of the titanium plate, and fixed with titanium microscrews 7mm long. The animals were evaluated clinically and radiographically until 90 days postoperatively. After this period, euthanasia was performed in 2 animals from each group. In all animals was observed bone healing and in group 1 the mean and standard deviation were 32.9±9.9 days, in group 2, 30.8±6.7 days in group 3, 26.6±6.4 days. There was no statistical difference in healing time between groups. The bending of the implant was the most common complication. The configuration of the plate resulted in a statistically significant difference in relation to walking and to the degree of bending in the different groups. Moreover, in group 3 there was higher precocity in the member suppor and a lower degree of bending in relation to other groups. Histologically, it was verified formation of the callus in all animals and presence of bone tissue around the plate and microscrews. Despite the complications of titanium microplates, they are an option for tibiotarsus osteosynthesis in birds of medium size.

Entre os problemas cirúrgicos das aves, as fraturas são os de maior prevalência. Em virtude das variações no tamanho, peso, anatomia óssea peculiar, alta incidência de fraturas complicadas e das diferentes demandas funcionais entre espécies e indivíduos, não foi possível estabelecer ainda um método ideal de osteossíntese para os ossos longos das aves. Microplacas de titânio comumente utilizadas em cirurgias maxilofaciais de humanos foram empregadas recentemente na osteossíntese de aves, porém com poucos resultados disponíveis. O objetivo do presente estudo foi avaliar a utilização das microplacas de titânio no tratamento de fraturas experimentais de tibiotarso em pombos domésticos (Columba livia). Foram utilizadas 30 aves adultas, machos e fêmeas, com 7 meses de idade, pesando entre 400 a 500 gramas. Os animais foram separados em três grupos de dez, sendo que no grupo 1 foi utilizado uma microplaca de titânio com 6 furos e espaçador central; no grupo 2, com oito furos sem espaçador central; e, no grupo 3, com oito furos com espaçador central. Após avaliação clínica, as aves foram submetidas à osteotomia médio-diafisária no tibiotarso direito para colocação das diferentes configurações de microplaca de titânio, sendo fixadas com microparafusos de titânio com 7mm de comprimento. Os animais foram avaliados clínica e radiograficamente até os 90 dias de pós-operatório. Após esse período, foi realizada eutanásia em duas aves de cada grupo. Em todas elas, foi observada a consolidação óssea, sendo que, no grupo 1, o tempo médio e o desvio padrão foram 32,9±9,9; no grupo 2, 30,8±6,7 e, no grupo 3, 26,6±6,4 dias, não havendo diferença estatística entre os grupos. O envergamento do implante foi a complicação mais frequente. A configuração da microplaca resultou em diferença estatisticamente significativa em relação à deambulação e ao grau de envergamento nos diferentes grupos, sendo que, no grupo 3, houve maior precocidade no apoio do membro e menor grau de envergamento em relação aos outros grupos. Histologicamente, foi verificada a formação de calo ósseo em todos os animais e presença de tecido ósseo ao redor da microplaca e dos microparafusos. Apesar das complicações observadas, as microplacas de titânio são uma opção para osteossíntese de tibiotarso em aves de médio porte.

RESUMO

Among the surgical problems in birds, the fractures are the most prevalent. Due to variations in size, weight, peculiar bone anatomy, high incidence of complicated fractures and functional demands of different species and individuals, it is still not possible to establish an ideal method for osteosynthesis of long bones in birds. Titanium microplates commonly used in human maxillofacial surgery have been recently employed in osteosynthesis of birds, but with few results available. The aim of this study was to evaluate the use of titanium microplates in the treatment of tibiotarsus fractures in 30 pigeons (Columba livia) , adult males and females, with 7 months old, weighing from 400 to 500. The animals were divided into 3 groups with ten animals each. In group 1, a titanium microplate with 6 holes and a central spacer was used; in group 2, a titanium microplate with 8 holes without a spacer in the center was used; in group 3, a titanium microplate with 8 holes with central spacer was used. After clinical evaluation, the birds were submitted to mid-diaphyseal osteotomy in the right bone for placement of different configurations of the titanium plate, and fixed with titanium microscrews 7mm long. The animals were evaluated clinically and radiographically until 90 days postoperatively. After this period, euthanasia was performed in 2 animals from each group. In all animals was observed bone healing and in group 1 the mean and standard deviation were 32.9±9.9 days, in group 2, 30.8±6.7 days in group 3, 26.6±6.4 days. There was no statistical difference in healing time between groups. The bending of the implant was the most common complication. The configuration of the plate resulted in a statistically significant difference in relation to walking and to the degree of bending in the different groups. Moreover, in group 3 there was higher precocity in the member suppor and a lower degree of bending in relation to other groups. Histologically, it was verified formation of the callus in all animals and presence of bone tissue around the plate and microscrews. Despite the complications of titanium microplates, they are an option for tibiotarsus osteosynthesis in birds of medium size.

Entre os problemas cirúrgicos das aves, as fraturas são os de maior prevalência. Em virtude das variações no tamanho, peso, anatomia óssea peculiar, alta incidência de fraturas complicadas e das diferentes demandas funcionais entre espécies e indivíduos, não foi possível estabelecer ainda um método ideal de osteossíntese para os ossos longos das aves. Microplacas de titânio comumente utilizadas em cirurgias maxilofaciais de humanos foram empregadas recentemente na osteossíntese de aves, porém com poucos resultados disponíveis. O objetivo do presente estudo foi avaliar a utilização das microplacas de titânio no tratamento de fraturas experimentais de tibiotarso em pombos domésticos (Columba livia). Foram utilizadas 30 aves adultas, machos e fêmeas, com 7 meses de idade, pesando entre 400 a 500 gramas. Os animais foram separados em três grupos de dez, sendo que no grupo 1 foi utilizado uma microplaca de titânio com 6 furos e espaçador central; no grupo 2, com oito furos sem espaçador central; e, no grupo 3, com oito furos com espaçador central. Após avaliação clínica, as aves foram submetidas à osteotomia médio-diafisária no tibiotarso direito para colocação das diferentes configurações de microplaca de titânio, sendo fixadas com microparafusos de titânio com 7mm de comprimento. Os animais foram avaliados clínica e radiograficamente até os 90 dias de pós-operatório. Após esse período, foi realizada eutanásia em duas aves de cada grupo. Em todas elas, foi observada a consolidação óssea, sendo que, no grupo 1, o tempo médio e o desvio padrão foram 32,9±9,9; no grupo 2, 30,8±6,7 e, no grupo 3, 26,6±6,4 dias, não havendo diferença estatística entre os grupos. O envergamento do implante foi a complicação mais frequente. A configuração da microplaca resultou em diferença estatisticamente significativa em relação à deambulação e ao grau de envergamento nos diferentes grupos, sendo que, no grupo 3, houve maior precocidade no apoio do membro e menor grau de envergamento em relação aos outros grupos. Histologicamente, foi verificada a formação de calo ósseo em todos os animais e presença de tecido ósseo ao redor da microplaca e dos microparafusos. Apesar das complicações observadas, as microplacas de titânio são uma opção para osteossíntese de tibiotarso em aves de médio porte.