Design of a high-Q fiber cavity for omnidirectionally emitting laser with one-dimensional topological photonic crystal heterostructure.

Designing a cavity with a high quality factor for omnidirectionally emitting laser (OEL) can extend its potential applications in optical communication and biomedical detection. We demonstrate a method including five steps to design a high-Q cavity for OEL using a one-dimensional topological photonic crystal heterostructure. A Si/SiO2 fiber cavity for OEL with solid gain medium Er-doped SiO2 is designed following our design steps. The designed fiber can axially transmit the pump energy at low confine loss and act as a cavity for the radial emission of the exited beam, simultaneously. The quality factor of this fiber cavity is on the order of magnitude of 108. Moreover, a method of further improving the Q-factor is proposed. The results in this paper are not restricted to the solid gain medium, and they also can be applied to designing a cavity for optofluidic OEL or quantum dot OEL. Our study may provide not only the reference for OEL manufacture, but also a route for improving the performance of OEL.

Evaluation of photolysis and hydrolysis of pyraclostrobin in aqueous solutions and its degradation products in paddy water.

This study evaluated the hydrolysis and photolysis kinetics of pyraclostrobin in an aqueous solution using ultra-high-performance liquid chromatography-photodiode array detection and identified the resulting metabolites of pyraclostrobin by hydrolysis and photolysis in paddy water using high-resolution mass spectrometry coupled with liquid chromatography. The effect of solution pH, metal ions and surfactants on the hydrolysis of pyraclostrobin was explored. The hydrolysis half-lives of pyraclostrobin were 23.1-115.5 days and were stable in buffer solution at pH 5.0. The degradation rate of pyraclostrobin in an aqueous solution under sunlight was slower than that under UV photolysis reaction. The half-lives of pyraclostrobin in a buffer solution at pH 5.0, 7.0, 9.0 and in paddy water were less than 12 h under the two light irradiation types. The metabolites of the two processes were identified and compared to further understand the mechanisms underlying hydrolysis and photolysis of pyraclostrobin in natural water. The extracted ions obtained from paddy water were automatically annotated by Compound Discoverer software with manual confirmation of their fragments. Two metabolites were detected and identified in the pyraclostrobin hydrolysis, whereas three metabolites were detected and identified in the photolysis in paddy water.

Determination of the residue dynamics and dietary risk of thiamethoxam and its metabolite clothianidin in citrus and soil by LC-MS/MS.

A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method was developed for the determination of thiamethoxam and its metabolite clothianidin in citrus (including the whole citrus, peel and pulp) and soil samples by liquid chromatography-tandem mass spectrometry. The sample was extracted with acetonitrile and purified with octadecylsilane. The detection limits of both compounds were 0.0001-0.0002 mg kg-1, while the limit of quantification of thiamethoxam was 0.002 mg kg-1 and the limit of quantitation of metabolites was 0.001 mg kg-1. The recovery was 70.37%-109.76%, with inter-day relative standard deviations (RSD) (n = 15) values ≤9.46% for the two compounds in the four matrices. The degradation curve of thiamethoxam in whole citrus and soil was plotted using the first-order kinetic model. The half-life of the whole citrus was 1.9-6.2 days, and the half-life of the soil was 3.9-4.2 days. The terminal residue of thiamethoxam (the sum of thiamethoxam and clothianidin, expressed as thiamethoxam) was found to be concentrated on the peel. The final residual amount of thiamethoxam in the edible portion (pulp) was less than 0.061 mg kg-1. The risk quotient values were all below 1, indicating that thiamethoxam as a citrus insecticide does not pose a health risk to humans at the recommended dosage.

PET/MR Imaging: New Frontier in Alzheimer's Disease and Other Dementias.

Alzheimer's disease (AD) is the most common form of dementia; a progressive neurodegenerative disease that currently lacks an effective treatment option. Early and accurate diagnosis, in addition to quick elimination of differential diagnosis, allows us to provide timely treatments that delay the progression of AD. Imaging plays an important role for the early diagnosis of AD. The newly emerging PET/MR imaging strategies integrate the advantages of PET and MR to diagnose and monitor AD. This review introduces the development of PET/MR imaging systems, technical considerations of PET/MR imaging, special considerations of PET/MR in AD, and the system's potential clinical applications and future perspectives in AD.

[Mutational analysis of RNA splicing machinery genes SF3B1, U2AF1 and SRSF2 in 118 patients with myelodysplastic syndromes and related diseases].

Objective: To investigate the incidence, molecular features and clinical significance of RNA splicing machinery genes mutation in myelodysplastic syndromes (MDS) and related diseases. Methods: Mutational analysis of splicing factor 3B subunit 1 (SF3B1) (K700E) , U2 small nuclear RNA auxiliary factor 1 (U2AF1) (S34, Q157P) and serine/arginine-rich splicing factor 2 (SRSF2) (P95) in 118, de novo MDS and related diseases were separately performed by using polymerase chain reaction (PCR) followed by sequence analysis. Results: Of 118 MDS patients, 76 males and 42 females, the median age was 53.5 (13-84) years old. 19.49% (23/118) had SF3B1 (K700E) mutation. As compared with those with wild type SF3B1, patients with SF3B1 K700E were of older[58 (32-78) years vs 51 (13-84) years, z=-1.981, P=0.048], lower HGB level[63 (40-95) g/L vs 77 (34-144) g/L, z=-3.192, P=0.001], higher platelet counts[121 (22-888) ×10(9)/L vs 59 (6-1 561) ×10(9)/L, z=-3.305, P=0.001], lower bone marrow blast cell counts[0.007 (0-0.122) vs 0.017 (0-0.268) , z=-2.885, P=0.004], higher ring sideroblasts percent [0 (0-64%) vs 0 (0-58%) , z=-4.664, P<0.001]. Of 105 MDS patients, 21.9% had U2AF1 (S34, Q157P) mutations. Of 107 MDS patients, 8 patients (7.48%) had SRSF2 (P95) mutations. Patients with SRSF2 mutations were older at diagnosis, the median age was 63 (50-84) years old, including 4 cases RAEB-1. The ratio of mutation was 14.29% (4/28) , and three patients transformed to AML. SF3B1 K700E and SRSF2 P95H mutations coexisted in 1 patient, and SF3B1 K700E and U2AF1 S34Y mutations were found concomitantly in 2 patients. Conclusion: Only SF3B1 gene mutation was closely related to ring sideroblasts, it was the key to pathogenesis of MDS.

DVP parametric imaging for characterizing ovarian masses in contrast-enhanced ultrasound.

AIM: To evaluate whether parametric imaging with contrast-enhanced ultrasound is an approach capable of for the differential diagnosis of ovarian masses. MATERIALS AND METHODS: The authors analysed 50 cases of ovarian masses by routine ultrasound and contrast-enhanced ultrasound with a new dedicated parametric image processing software-Sonoliver. The angiogenesis and blood perfusion mode on a digital video recorder were recorded and the morphological characteristics of time-intensity curve (TIC) and dynamic vascular pattern (DVP) curve were subsequently described. The quantity factor, including time to peak (TTP), maximum intensity (IMAX), rise time, (RT), mean transit time (mTT), generated by Sonoliver software were compared in both histological gradings. RESULTS: There were 24 cases (86%) displaying mainly hypo-enhanced with blue imaging in those with benign masses and 15 cases (68%) displaying mainly hyper-enhanced imaging with red in those with malignant masses. The difference was statistically significant (p < 0.05). DVP curves were unipolar below the baseline in 23 cases (82%) of benign masses and unipolar above the baseline in 15 cases (68%) of malignant masses. IMAX, TTP, and mTT were all significantly higher in those with malignant masses than those with benign ones (all p < 0.05), but, no statistical difference in the RT between the two groups was found (p > 0.05). CONCLUSIONS: According to the results, DVP parametric imaging is a new approach capable of differential diagnoses of overian masses with contrast-enhanced ultrasound.

Water-Soluble Silicon Quantum Dots with Quasi-Blue Emission.

In this study, water-soluble silicon quantum dots have quasi-blue emission at 390 nm by being capped with 1-vinylimidazole in resese micelles. As-obtained silicon quantum dots have a diameter of 2~5 nm and high crystallinity. The quasi-blue emission of the silicon quantum dots is likely attributed to the polarity of the capping ligands. Moreover, the silicon quantum dots are water-soluble and have photoluminescence nanosecond decay time, suggesting their potential application in biological field.

Analysis of metabolic flux in Escherichia coli expressing human-like collagen in fed-batch culture.

Metabolic flux distributions of recombinant Escherichia coli BL21 expressing human-like collagen were determined by means of a stoichiometric network and metabolic balancing. At the batch growth stage, the fluxes of the pentose phosphate pathway were higher than the fluxes of the fed-batch growth phase and the production stage. After the temperature was increased, there was a substantially elevated energy demand for synthesizing human-like collagen and heat-shock proteins, which resulted in changes in metabolic fluxes. The activities of the Embden-Meyerhof-Parnas pathway and the tricarboxylic acid cycle were significantly enhanced, leading to a reduction in the fluxes of the pentose phosphate pathway and other anabolic pathways. The temperature upshift also caused an increase in NADPH production by isocitrate dehydrogenase in the tricarboxylic acid cycle. The metabolic model predicted the involvement of a transhydrogenase that generates additional NADH from NADPH, thereby increasing ATP regeneration in the respiratory chain. These data indicated that the maintenance energy for cellular activity increased with the increase in biomass in fed-batch culture, and that cell growth and synthesis of human-like collagen could clearly represent the changes in metabolic fluxes. At the production stage, more NADPH was used to synthesize human-like collagen than for maintaining cellular activity, cell growth, and cell propagation.

[Ecological analysis and optimization design for agricultural landscape of coastal zone along Radial Submarine Sand Ridges in north Jiangsu].

The Radial Submarine Sand Ridges (RSSR) on the inner shelf of the Southwestern Yellow Sea is one of the largest of such system in the world. It was developed into great amount of land which is mainly used for agriculture. However, the coastal zone is facing many serious environmental and resources problems such as coastal erosion, ecological fragility and over- and abuse of coastal resources. Based on comprehensive field survey, this paper proposes optimization allocation and design of agri-landscape spatial structures targeting an integrated improvement in agricultural ecology, economy and amenity of the region as well as implementation of sustainable development strategy. As a case study, rectification approaches and conceptual optimization design for Rudong County are proposed and discussed.