Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 45
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Intervalo de ano de publicação
1.
Paediatr Anaesth ; 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38803119

RESUMO

Tonsillectomy is one of the most common surgical procedures in childhood. While generally safe, it often is associated with a difficult early recovery phase with poor oral intake, dehydration, difficult or painful swallowing, postoperative bleeding, infection and/or otalgia. Better pain management and the availability of more child friendly medications are within the top consumer priorities in perioperative medicine, highlighting the importance of alternative pain treatments. This review focuses on the potential role of honey in the postoperative setting, its effects, and mechanisms of action. While the application of honey post-tonsillectomy may offer analgesic and healing benefits, it may also reduce postoperative bleeding. A systematic search was carried out using the search terms honey, tonsillectomy. Filters were applied to human studies and English. No other search terms were used or age filters applied to yield a broader range of results. Seven pediatric, four adult, and two studies of mixed pediatric and adult patients with sample sizes ranging from 8 to 52 patients were included in this review. Effect sizes ranged from small to huge across the studies. While the application of honey post-tonsillectomy may offer analgesic and healing benefits, it may also reduce postoperative bleeding. However, while there are potential benefits based on the chemical composition of honey, the current literature is of variable quality and there is need for high quality clinical trials.

2.
Zhonghua Yi Xue Za Zhi ; 104(30): 2805-2809, 2024 Aug 06.
Artigo em Zh | MEDLINE | ID: mdl-39085147

RESUMO

Objective: To explore the association between obesity/overweight and the risk of malignancy in Hürthle cell neoplasms of the thyroid. Methods: The data of patients with complete data who were diagnosed with Hürthle cell neoplasms of the thyroid at the Third Hospital of Peking University from September 2016 to September 2023 were retrospectively collected. Based on postoperative pathological diagnosis, tumors were classified into thyroid Hürthle cell adenoma group and Hürthle cell carcinoma group. Multivariate logistic regression analysis was employed to explore the association between overweight/obesity and the risk of malignancy in Hürthle cell neoplasms of the thyroid. Results: A total of 102 patients (13 males and 89 females) were included, aged (48.7±13.1) years. There were 22 cases of thyroid Hürthle cell carcinoma and 80 cases of thyroid Hürthle cell adenoma. Univariate analysis showed that the rate of overweight/obesity in the Hürthle cell carcinoma group was higher than that in the adenoma group [73% (16/22) vs 46% (37/80), P=0.050]. Multivariate logistic regression analysis indicated that the overweight/obese patients had a higher risk of malignancy in Hürthle cell neoplasms of the thyroid compared with the non-overweight/obese patients (OR=3.170, 95%CI: 1.126-9.955, P=0.035). Sensitivity analysis excluding individuals with multiple tumors was consistent with the main study results (OR=2.878, 95%CI: 0.922-10.228, P=0.080). Conclusion: Overweight/obesity may be associated with a higher risk of malignancy in patients with Hürthle cell neoplasms of the thyroid.


Assuntos
Adenoma Oxífilo , Obesidade , Sobrepeso , Neoplasias da Glândula Tireoide , Humanos , Masculino , Feminino , Adenoma Oxífilo/patologia , Pessoa de Meia-Idade , Neoplasias da Glândula Tireoide/etiologia , Neoplasias da Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/epidemiologia , Estudos Retrospectivos , Obesidade/complicações , Fatores de Risco , Sobrepeso/complicações , Adulto , Modelos Logísticos , Adenoma/patologia , Adenoma/epidemiologia
3.
Zhonghua Wai Ke Za Zhi ; 61(3): 209-213, 2023 Mar 01.
Artigo em Zh | MEDLINE | ID: mdl-36650966

RESUMO

Objective: To examine the short-term curative effect with minimally invasive right infra-axillary thoracotomy for transaortic modified Morrow procedure. Methods: The clinical data of 60 patients who underwent video-assisted thoracoscopic transaortic modified Morrow procedure from August 2021 to August 2022 at Department of Cardiovascular Surgery, Zhejiang Provincial People's Hospital were retrospectively analyzed. There were 31 males and 29 females, with the age (M (IQR)) of 54.0(22.3) years (range: 15 to 71 years). The echocardiography confirmed the diagnosis of moderate mitral regurgitation in 30 patients, and severe mitral regurgitation in 13 patients. Systolic anterior motion (SAM) was present preoperatively in 54 patients. All 60 patients underwent transaortic modified Morrow procedure through a right infra-axillary thoracotomy using femorofemoral cardiopulmonary bypass. Surgical procedures mainly included transverse aortic incision, exposure of left ventricular outflow tract (LVOT), septal myectomy, and correction of the abnormal mitral valve and subvalvular structures. Results: All 60 patients underwent the programmatic procedures successfully without conversion to full sternotomy. The cardiopulmonary bypass time was (142.0±32.1) minutes (range: 89 to 240 minutes), while the cross-clamp time was (95.0±23.5) minutes (range: 50 to 162 minutes). The patients had a postoperative peak LVOT gradient of 7.0 (5.0) mmHg (range: 0 to 38 mmHg) (1 mmHg=0.133 kPa). A total of 57 patients were extubated on the operating table. The drainage volume in the first 24 h was (175.9±57.0) ml (range: 60 to 327 ml). The length of intensive care unit stay was 21.0 (5.8)h (range: 8 to 120 h) and postoperative hospital stay was 8 (5) days (range: 5 to 19 days). The postoperative septal thickness was 11 (2) mm (range: 8 to 14 mm). All patients had no iatrogenic ventricular septal perforation or postoperative residual SAM. The patients were followed up for 4 (9) months (range: 1 to 15 months), and none of them needed cardiac surgery again due to valve dysfunction or increased peak LVOT gradient during follow-up. Conclusion: Using a video-assisted thoracoscopic transaortic modified Morrow procedure through a right infra-axillary minithoracotomy can provide good visualization of the LVOT and hypertrophic ventricular septum, ensure optimal exposure of the mitral valve in the presence of complex mitral subvalvular structures, so that allows satisfactory short-term surgical results.


Assuntos
Cardiomiopatia Hipertrófica , Insuficiência da Valva Mitral , Septo Interventricular , Masculino , Feminino , Humanos , Insuficiência da Valva Mitral/cirurgia , Toracotomia , Estudos Retrospectivos , Cardiomiopatia Hipertrófica/cirurgia , Septo Interventricular/cirurgia , Resultado do Tratamento , Procedimentos Cirúrgicos Minimamente Invasivos/métodos
4.
Zhonghua Wai Ke Za Zhi ; 60(1): 63-68, 2022 Jan 01.
Artigo em Zh | MEDLINE | ID: mdl-34954949

RESUMO

Objective: To analyze the treatment and clinical prognosis of lower extremity arterial injury caused by trauma. Methods: The clinical data of 77 patients with traumatic lower extremity arterial injury admitted to Department of Vascular Surgery,Yichang Central People's Hospital from January 2013 to June 2021 were collected retrospectively. There were 65 males and 12 females, with an average age of 47.4 years (range: 7 to 75 years). Among the 77 patients, 56 cases (72.7%) had open injury and 21 cases (27.3%) had closed injury. Iliac artery was injured in 9 cases (11.7%), common femoral artery in 7 cases (9.1%), superficial femoral artery in 1 case (1.3%), popliteal artery in 11 cases (14.3%) and inferior knee artery in 49 cases (63.6%). The treatment methods and clinical effects were analyzed. Results: One case with pelvic fracture combined the internal iliac artery injury and 1 case with multiple injuries involving the common femoral artery died of circulatory failure before surgery. Seventy-five cases received vascular-related operations, including arterial ligation in 24 cases, arterial reconstruction in 40 cases, stent graft implantation in 1 case, primary amputation in 2 cases, and arterial embolization in 8 cases. The overall mortality rate was 6.5% (5/77), all of which were closed injuries. Except for 2 cases who died before surgery, 3 cases with pelvic fracture combined the internal iliac artery injury died of multiple organ failure after internal iliac artery embolization. There were 8 cases received amputation (10.4%, 8/77), 5 cases with closed injury and 3 cases with open injury. In addition to 2 cases with primary amputation, 6 cases underwent secondary amputation due to ischemia-reperfusion injury after revascularization (4 cases with popliteal artery injury and 2 cases with subpatellar artery injury). The average followed-up time was 17 months (range: 2 months to 8 years). One patient with femoral artery injury underwent autologous great saphenous vein bypass, and lower limb artery CT angiography was re-examined 6 months after the operation, and 30% distal anastomotic stenosis was found. Ankle brachial index<0.8 was found in two patients 1 year after popliteal artery repair, but none of the patients had intermittent claudication symptoms, and no further intervention was performed. Five patients suffered delayed healing due to severe lower limb injury, fracture and skin injury. Among them, 2 cases had poor wound healing at the stump of amputation, which gradually healed 3 to 5 months after several debridements. The other 3 vascular injury combined with tibial fracture patients had delayed tibial healing after surgery, but no symptoms of vascular ischemia occurred. All the other patients recovered well and no other serious complications occurred. Conclusions: The proportion of death and disability in patients with lower limb artery injury caused by trauma is high. Active and orderly surgical repair according to the site and type of injury can reduce the mortality, save the function of the affected limb, and promote the healing of injury.


Assuntos
Lesões do Sistema Vascular , Amputação Cirúrgica , Feminino , Artéria Femoral , Humanos , Extremidade Inferior , Masculino , Pessoa de Meia-Idade , Artéria Poplítea/cirurgia , Estudos Retrospectivos , Resultado do Tratamento , Lesões do Sistema Vascular/cirurgia
5.
J Intern Med ; 289(5): 738-746, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33511686

RESUMO

BACKGROUND: Published reports on tocilizumab in COVID-19 pneumonitis show conflicting results due to weak designs or heterogeneity in critical methodological issues. METHODS: This open-label trial, structured according to Simon's optimal design, aims to identify factors predicting which patients could benefit from anti-IL6 strategies and to enhance the design of unequivocal and reliable future randomized trials. A total of 46 patients with COVID-19 pneumonia needing of oxygen therapy to maintain SO2 > 93% and with recent worsening of lung function received a single infusion of tocilizumab. Clinical and biological markers were measured to test their predictive values. Primary end point was early and sustained clinical response. RESULTS: Twenty-one patients fulfilled pre-defined response criteria. Lower levels of IL-6 at 24 h after tocilizumab infusion (P = 0.049) and higher baseline values of PaO2/FiO2 (P = 0.008) predicted a favourable response. CONCLUSIONS: Objective clinical response rate overcame the pre-defined threshold of 30%. Efficacy of tocilizumab to improve respiratory function in patients selected according to our inclusion criteria warrants investigations in randomized trials.


Assuntos
Anticorpos Monoclonais Humanizados , Biomarcadores Farmacológicos/análise , COVID-19 , Monitoramento de Medicamentos/métodos , Interleucina-6 , Pneumonia Viral , Idoso , Anticorpos Monoclonais Humanizados/administração & dosagem , Anticorpos Monoclonais Humanizados/farmacocinética , COVID-19/diagnóstico , COVID-19/epidemiologia , COVID-19/fisiopatologia , COVID-19/terapia , Feminino , Humanos , Fatores Imunológicos/administração & dosagem , Fatores Imunológicos/farmacocinética , Infusões Intravenosas , Interleucina-6/antagonistas & inibidores , Interleucina-6/sangue , Itália/epidemiologia , Masculino , Oximetria/métodos , Oxigenoterapia/métodos , Pneumonia Viral/tratamento farmacológico , Pneumonia Viral/epidemiologia , Pneumonia Viral/etiologia , Valor Preditivo dos Testes , Testes de Função Respiratória/métodos , SARS-CoV-2/isolamento & purificação , Resultado do Tratamento
6.
Zhonghua Wai Ke Za Zhi ; 59(8): 716-720, 2021 Aug 01.
Artigo em Zh | MEDLINE | ID: mdl-34192866

RESUMO

With the development of endovascular technology for peripheral arterial diseases, paclitaxel drug-eluting stents and drug-coated balloons have been widely used in recent years. It has been proved that paclitaxel-coated devices have good clinical effects in reducing vascular restenosis. However, the clinical safety of paclitaxel devices has encountered challenges, some of the studies have shown that paclitaxel-coated devices may increase long-term mortality. In addition, some studies have confirmed the effectiveness and safety of paclitaxel devices, leading to this topic becoming the focus and hot spot of global attention. Whether paclitaxel-coated devices increase the risk of long-term death, whether paclitaxel doses are related to mortality, and the pharmacokinetics of paclitaxel devices should be examined.

7.
Beijing Da Xue Xue Bao Yi Xue Ban ; 51(2): 210-220, 2019 Apr 18.
Artigo em Zh | MEDLINE | ID: mdl-30996356

RESUMO

OBJECTIVE: LASS2/TMSG1 gene is a novel tumor metastasis suppressor gene cloned from human prostate cancer cell line PC-3M in 1999 by Department of Pathology,Peking University of Basic Medical Sciences. It was found out that protein encoded by LASS2/TMSG1 could interact with the c subunit of vacuolar-ATPase (ATP6V0C). In this study, we explored the effect of LASS2/TMSG1 and its mutants on proliferation, migration and invasion of human prostate cancer cells and its molecular mechanism. METHODS: We constructed four LASS2/TMSG1 mutants and stably transfected the variants to human prostate cancer cell line PC-3M-1E8 cell with high metastatic potential. The stable transfectants were identified by qPCR and Western blot through analyzing the expression of LASS2/TMSG1 and ATP6V0C, the cell biology functions of LASS2/TMSG1 and its four mutants were studied using growth curve,MTT assay, soft agar colony formation assay, wound migration assay, Matrigel invasion study and flow cytometry. Furthermore, immunofluorescence was used to analysis the interaction of LASS2/ TMSG1 mutants and ATP6V0C. RESULTS: LASS2/TMSG1 mRNA and protein in LASS2/TMSG1 group and Mut1-Mut4 groups were higher than that in Vector group; Western blot showed that ATP6V0C protein in LASS2/TMSG1 wild group was lower than that in Vector group, but ATP6V0C protein in LASS2/TMSG1 S248A group was obviously higher than that in Vector group. MTT test and growth curve assay showed growth ability in LASS2/TMSG1 S248A group was increasing compared with other groups from day 5. Soft Agar colony formation experiment showed anchor independent growth ability in LASS2/TMSG1 S248A group was higher than those in the other groups (P<0.05), Cell migrations (from 35.3%±3.2% to 70.3%±3%) in LASS2/TMSG1 S248A group was increasing compared with LASS2/TMSG1 wild group (P<0.01), and more cells passed through Matrigel in LASS2/TMSG1 S248A group compared with LASS2/TMSG1 wild group (from 50±3.2 to 203±6.5, P<0.01), the apoptosis rate in LASS2/TMSG1 S248A group was obviously higher than that in LASS2/TMSG1 wild group (from 7% to 15.1%, P<0.05), and the G0/G1 ratio in LASS2/TMSG1 S248A group was obviously higher than that in LASS2/TMSG1 wild group (from 51.0% to 85.4%). Furthermore, double immunofluorescent staining observed the colocalization between ATP6V0C and LASS2/TMSG1 protein and its mutations, the expression of ATP6V0C in LASS2/TMSG1 S248A group increased significantly compared with the other groups. CONCLUSION: LASS2/TMSG1 S248A promotes proliferation, migration and invasion of prostate cancer cells through increasing ATP6V0C expression, suggesting that aa248-250 is an important function site for LASS2/TMSG1 in invasion suppression of prostate cancer cells.


Assuntos
Proteínas de Membrana/genética , Neoplasias da Próstata , Esfingosina N-Aciltransferase/genética , Proteínas Supressoras de Tumor/genética , Pequim , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Humanos , Masculino , Mutação , Invasividade Neoplásica , Neoplasias da Próstata/genética , Transfecção , ATPases Vacuolares Próton-Translocadoras
8.
Opt Lett ; 42(19): 3856-3859, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28957144

RESUMO

We investigate the evolution of the state of polarization of light propagating through bulk depoled composite ferroelectrics below the Curie temperature. In contrast to standard depoled ferroelectrics, where random birefringence causes depolarization and scattering, light is observed to suffer varying degrees of depolarization and remains fully polarized when linearly polarized along the crystal principal axes. The effect is found to be supported by the formation of polarized speckles organized into a spatial lattice and occurs as the ferroelectric settles into a spontaneous super-crystal, a three-dimensional coherent mosaic of ferroelectric clusters. The polarization lattices gradually disappear as the ferroelectric state reduces to a disordered distribution of polar nanoregions above the critical point.

9.
Beijing Da Xue Xue Bao Yi Xue Ban ; 49(6): 1076-1080, 2017 Dec 18.
Artigo em Zh | MEDLINE | ID: mdl-29263485

RESUMO

Pulmonary adenofibroma is an extremely rare benign primary tumor of the lung, with characteristic bi-phasic differential pattern. They are usually sub-pleural solid pulmonary nodules with clear margins. The tumor is composed of glands and peri-gland stroma. The glands are often quite simple, forming long and narrow tubules, with uniformly monolayer lining cells. Combined papillary or phyllodes structures were reported in some cases. The stromal cells are spindle-shaped and look mild, mixed with the collagen bands. Up till now, only a few cases of pulmonary adenofibroma have been reported all over the world. And because of the limited recognition, this tumor is easily misinterpreted as malignancy in frozen section or biopsy specimens. We reported a new case of pulmonary adenofibroma. The mass peripherally located in the left lobe of the lung, found by chance in a 74-year-old woman. The patient underwent a wedge resection of the left lung by the thoracoscope, because of the slowly gradual enlargement of the mass annually. An oval grayish-white nodule was sub-pleural located in the specimen, with solid and rubbery texture, but without a distinct capsule. Two distinct components of simple glands and mild spindle cell stroma were found to mix together uniformly under the microscope. Collagen bands of various widths evenly surrounded each stromal cell. A few small coarse papillae or phyllodes structures were randomly distributed in some area. The immunohistochemical staining pattern of the glandular cells was accordant with typeIIalveolar epithelium. Stromal cells were positive with CD34, B-cell lymphoma-2 (Bcl-2), CD99 and estrogen receptor (ER), while S-100, smooth muscle actin (SMA) and all the mesothe-lium markers were negative. The patient was disease free after the surgery, although the follow-up time was only one year. Besides the new case above, we also reviewed all the reported cases, and tentatively discussed the probable histological origin of pulmonary adenofibroma.


Assuntos
Adenofibroma/diagnóstico , Neoplasias Pulmonares/diagnóstico , Idoso , Biomarcadores Tumorais , Feminino , Humanos , Imuno-Histoquímica , Células Estromais
10.
Beijing Da Xue Xue Bao Yi Xue Ban ; 49(6): 937-947, 2017 Dec 18.
Artigo em Zh | MEDLINE | ID: mdl-29263462

RESUMO

OBJECTIVE: Vacuolar ATPase (V-ATPase) was found within the membranes and internal organelles of a vast array of eukaryotic cells, and was related to various kinds of highly metastatic tumors. LASS2/TMSG1 gene was a novel tumor metastasis suppressor gene cloned from human prostate cancer cell line PC-3M in 1999 by our laboratory. It was found out that protein encoded by LASS2/TMSG1 could interact with the c subunit of V-ATPase (ATP6V0C). In this study, To use RNA interference to suppress the expression of ATP6V0C and try to further investigate the molecular mechanism of ATP6V0C in tumor metastasis and its relationship with LASS2/TMSG1 gene. METHODS AND RESULTS: The expression level of ATP6V0C mRNA and protein in high metastatic potential prostate cancer cell lines (PC-3M-1E8 and PC-3M) was significantly higher than that in low metastatic potential prostate cancer cell lines (PC-3M-2B4 and PC-3), the expression level in PC-3M-1E8 being the highest. Follow-up tests selected PC-3M-1E8 cells for gene silencing. The expression and secretion of MMP-2 and the expression of MMP-9 in ATP6V0C siRNA transfected PC-3M-1E8 cells displayed no obvious change, but the activity of secreted MMP-9 was abated noticeably compared with the controls (P<0.05). Extracellular hydrogen ion concentration and V-ATPase activity in interference group were both reduced significantly compared with the controls (P<0.05). The migration and invasion capacity of ATP6V0C siRNA interfered cells in vitro were diminished significantly compared with the controls (P<0.05). Furthermore, a dramatic reduction of LASS2/TMSG1 mRNA and protein level after transfection of siRNA in PC-3M-1E8 cells was discovered (P<0.05). Confocal immunofluorescence showed a vast co-localization of ATP6V0C protein and LASS2/TMSG1 protein in plasma and membrane. The co-localization signals of control group were much stronger than those of interference group. CONCLUSION: Specific siRNA silencing of ATP6V0C gene inhi-bits the invasion of human prostate cancer cells in vitro by mechanism of inhibiting V-ATPase activity and then reducing the extracellular hydrogen ion concentration, inhibiting MMP-9 activation and affecting ECM degradation and reconstruction. Meanwhile, ATP6V0C and LASS2/TMSG1 have interaction and it is likely that ATP6V0C functions as a feedback regulator of LASS2/TMSG1.


Assuntos
Invasividade Neoplásica , Neoplasias da Próstata/patologia , RNA Interferente Pequeno , Esfingosina N-Aciltransferase , ATPases Vacuolares Próton-Translocadoras/fisiologia , Contagem de Células , Linhagem Celular Tumoral , Inativação Gênica , Humanos , Concentração de Íons de Hidrogênio , Masculino , Metaloproteinase 2 da Matriz , Metaloproteinase 9 da Matriz , Proteínas de Membrana , Interferência de RNA , RNA Mensageiro , Transfecção , Proteínas Supressoras de Tumor
11.
Zhonghua Bing Li Xue Za Zhi ; 46(1): 14-19, 2017 Jan 08.
Artigo em Zh | MEDLINE | ID: mdl-28072970

RESUMO

Objective: To study the relationship between morphological characteristics, grading, diagnosis and prognosis in phyllodes tumors (PT) of the breast. Methods: A retrospective study was carried out on 83 PTs diagnosed between 1999 and 2003 that were classified semi-quantitatively according to the WHO recommendation. Follow-up data was available for some cases, and Cox regression analysis was used to evaluate factors affecting metastasis and recurrence. Results: All cases were classified into the benign (57.8%), borderline (28.9%) and malignant (13.3%). The overall recurrence rate for the 72 cases with follow-up data was 20.8% (15/72), and was 17.5% (7/40) in benign, 22.7% (5/22) in borderline and 3/10 in malignant PT, respectively, with no significant difference (P>0.05). The median interval between the initial diagnosis and the first recurrence was 24 months. Lung or bone metastases occurred in 1/22 borderline and 3/10 malignant PT patients 5 years post-surgery. The mitotic count and the degree of stromal cell atypia were significantly correlated with recurrence (P=0.001 and P=0.006). Multivariate analysis showed that severe stromal cell atypia was an independent predictor of recurrence-free survival in PT [HR=6.40 (95% CI=1.378 to 29.732), P=0.018]. Conclusions: Each parameter in the histological grading of PT may have different prognostic value, and markedly increased mitotic count and were predictive of relapse.


Assuntos
Neoplasias da Mama/patologia , Recidiva Local de Neoplasia , Tumor Filoide/patologia , Neoplasias Ósseas/secundário , Feminino , Humanos , Neoplasias Pulmonares/secundário , Análise Multivariada , Gradação de Tumores , Prognóstico , Análise de Regressão , Estudos Retrospectivos , Células Estromais/patologia
12.
Phys Rev Lett ; 117(18): 183902, 2016 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-27834998

RESUMO

We report the direct observation of the onset of turbulence in propagating one-dimensional optical waves. The transition occurs as the disordered hosting material passes from being linear to one with extreme nonlinearity. As the response grows, increased wave interaction causes a modulational unstable quasihomogeneous flow to be superseded by a chaotic and spatially incoherent one. Statistical analysis of high-resolution wave behavior in the turbulent regime unveils the emergence of concomitant rogue waves. The transition, observed in a photorefractive ferroelectric crystal, introduces a new and rich experimental setting for the study of optical wave turbulence and information transport in conditions dominated by large fluctuations and extreme nonlinearity.

13.
Phys Rev Lett ; 116(15): 153902, 2016 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-27127969

RESUMO

We propose and provide experimental evidence of a mechanism able to support negative intrinsic effective mass. The idea is to use a shape-sensitive nonlinearity to change the sign of the mass in the leading linear propagation equation. Intrinsic negative-mass dynamics is reported for light beams in a ferroelectric crystal substrate, where the diffusive photorefractive nonlinearity leads to a negative-mass Schrödinger equation. The signature of inverted dynamics is the observation of beams repelled from strongly guiding integrated waveguides irrespective of wavelength and intensity and suggests shape-sensitive nonlinearity as a basic mechanism leading to intrinsic negative mass.

14.
Opt Lett ; 40(7): 1386-9, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25831339

RESUMO

We demonstrate the integration of a miniaturized 30(x) µm×30(y) µm×2.7(z) mm electro-optic phase modulator operating in the near-IR (λ=980 nm) based on the electro-activation of a funnel waveguide inside a paraelectric sample of photorefractive potassium lithium tantalate niobate. The modulator forms a basic tassel in the realization of miniaturized reconfigurable optical circuits embedded in a single solid-state three-dimensional chip.

15.
Phys Rev Lett ; 115(9): 093901, 2015 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-26371654

RESUMO

Rogue waves are observed as light propagates in the extreme nonlinear regime that occurs when a photorefractive ferroelectric crystal is undergoing a structural phase transition. The transmitted spatial light distribution contains bright localized spots of anomalously large intensity that follow a signature long-tail statistics that disappears as the nonlinearity is weakened. The isolated wave events form as out-of-equilibrium response and disorder enhance the Kerr-saturated nonlinearity at the critical point. Self-similarity associable to the individual observed filaments and numerical simulations of the generalized nonlinear Schrödinger equation suggests that dynamics of soliton fusions and scale invariance can microscopically play an important role in the observed rogue intensities and statistics.

16.
Phys Rev Lett ; 114(20): 203901, 2015 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-26047230

RESUMO

We study theoretically and experimentally the propagation of optical solitons in a lattice nonlinearity, a periodic pattern that both affects and is strongly affected by the wave. Observations are carried out using spatial photorefractive solitons in a volume microstructured crystal with a built-in oscillating low-frequency dielectric constant. The pattern causes an oscillating electro-optic response that induces a periodic optical nonlinearity. On-axis results in potassium-lithium-tantalate-niobate indicate the appearance of effective continuous saturated-Kerr solitons, where all spatial traces of the lattice vanish, independently of the ratio between beam width and lattice constant. Decoupling the lattice nonlinearity allows the detection of discrete delocalized and localized light distributions, demonstrating that the continuous solitons form out of the combined compensation of diffraction and of the underlying periodic volume pattern.

17.
Opt Express ; 22(25): 31434-9, 2014 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-25607093

RESUMO

Anti-diffraction is a theoretically predicted nonlinear optical phenomenon that occurs when a light beam spontaneously focalizes independently of its intensity. We observe anti-diffracting beams supported by the peak-intensity-independent diffusive nonlinearity that are able to shrink below their diffraction-limited size in photorefractive lithium-enriched potassium-tantalate-niobate (KTN:Li).

18.
Opt Lett ; 39(6): 1657-60, 2014 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-24690862

RESUMO

We study the formation of 2D self-trapped beams in nanodisordered potassium-sodium-tantalate-niobate (KNTN) cooled below the dynamic glass transition. Supercooling is shown to accelerate the photorefractive response and enhance steady-state anisotropy. Effects in the excited state are attributed to the anomalous slim-loop polarization curve typical of relaxors dominated by non-interacting polar-nano-regions.


Assuntos
Vidro/química , Nanopartículas Metálicas/química , Refratometria/métodos , Ligas/química , Luz , Teste de Materiais , Agulhas , Espalhamento de Radiação
20.
Planta ; 238(5): 969-82, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23975011

RESUMO

The development and regulation of aerenchyma in waterlogged conditions were studied in the seminal roots of wheat. Evans blue staining and the first cell death position indicated that the cortical cell death began at the root mid-cortex cells in flooding conditions. Continuous waterlogging treatment caused the spread of cell death from the mid-cortex to the neighboring cells and well-developed aerenchyma was formed after 72 h. Meanwhile, the formation of radial oxygen loss barrier was observed in the exodermis owing to the induction of Casparian bands and lignin deposition. Analysis of aerenchyma along the wheat root revealed that aerenchyma formed at 10 mm from the root tip, significantly increased toward the center of the roots, and decreased toward the basal region of the root. In situ detection of radial oxygen species (ROS) showed that ROS accumulation started in the mid-cortex cells, where cell death began indicating that cell death was probably accompanied by ROS production. Further waterlogging treatments resulted in the accumulation of ROS in the cortical cells, which were the zone for aerenchyma development. Accumulation and distribution of H2O2 at the subcellular level were revealed by ultracytochemical localization, which further verified the involvement of ROS in the cortical cell death process (i.e., aerenchyma formation). Furthermore, gene expression analysis indicated that ROS production might be the result of up-regulation of genes encoding for ROS-producing enzymes and the down-regulation of genes encoding for ROS-detoxifying enzymes. These results suggest that aerenchyma development in wheat roots starts in the mid-cortex cells and its formation is regulated by ROS.


Assuntos
Raízes de Plantas/citologia , Raízes de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Triticum/citologia , Triticum/metabolismo , Água/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genes de Plantas/genética , Homeostase/efeitos dos fármacos , Homeostase/genética , Meristema/citologia , Meristema/metabolismo , Modelos Biológicos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/ultraestrutura , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Triticum/genética , Triticum/ultraestrutura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA