Analysis of refraction and scattering image artefacts in x-ray analyzer-based imaging

X-ray analyzer-based imaging(ABI) is a powerful phase-sensitive technique that can provide a wide dynamic range of density and extract useful physical properties of the sample. It derives contrast from x-ray absorption, refraction, and scattering properties of the investigated sample. However, x-ray ABI setups can be susceptible to external vibrations, and mechanical imprecisions of system components, e.g., the precision of motor, which are unavoidable in practical experiments. Those factors will provoke deviations of analyzer angular positions and hence errors in the acquired image data.Consequently, those errors will introduce artefacts in the retrieved refraction and scattering images. These artefacts are disadvantageous for further image interpretation and tomographic reconstruction. For this purpose, this work aims to analyze image artefacts resulting from deviations of analyzer angular positions. Analytical expressions of the refraction and scattering image artefacts are derived theoretically and validated by synchrotron radiation experiments. The results show that for the refraction image, the artefact is independent of the sample’s absorption and scattering signals. By contrast, artefact of the scattering image is dependent on both the sample’s refraction and scattering signals, but not on absorption signal.Furthermore, the effect of deviations of analyzer angular positions on the accuracy of the retrieved images is investigated,which can be of use for optimization of data acquisition. This work offers the possibility to develop advanced multi-contrast image retrieval algorithms that suppress artefacts in the retrieved refraction and scattering images in x-ray analyzer-based imaging.

结核性脑膜炎患者行脑脊液腺苷脱氨酶及其他生化项目检测的临床意义

目的研究结核性脑膜炎患者脑脊液生化检测结果及其动态变化特点,探讨其对临床判断患者病情的指导意义。方法收集2011年1月至2014年9月河北省胸科医院神经内科收治入院的确定诊断和可能诊断(Thwaites诊断标准)的46例结核性脑膜炎患者,对患者脑脊液生化指标[包括氯化物、蛋白、葡萄糖、腺苷脱氨酶(ADA)]、病情分级[按照英国医学研究委员会(MRC)的分期标准:Ⅰ期、Ⅱ期和Ⅲ期]情况进行相关性分析,以及对治疗过程中脑脊液生化检测指标的动态变化及临床意义进行探讨。结果仅脑脊液ADA水平[中位数(四分位数)]随MRC分期增高而明显增高,分别为:Ⅰ期2.00(1.00,5.50)U/L;Ⅱ期3.00(2.00,5.75)U/L;Ⅲ期7.50(4.33,10.00)U/L(H=6.695,P=0.035)。经不同分期两两比较后发现,Ⅲ期患者脑脊液ADA、氯化物水平[102.70(98.10,115.45)mmol/L]明显高于Ⅰ期患者的ADA和氯化物[118.00(111.80,122.60)mmol/L](U=13.609,P=0.033;U=2.122,P=0.035)。46例患者经规范治疗后脑脊液生化指标均逐渐好转,表现为在治疗1、2、4周时脑脊液氯化物分别为118.10(110.30,121.55)、120.00(115.93,122.55)、121.95(117.78,125.90)mmol/L;葡萄糖分别为2.48(2.11,2.91)、2.79(2.31,3.35)、3.03(2.49,3.43)mmol/L;均较入院时[分别为114.75(103.05,118.55)、2.14(1.67,2.99)mmol/L]明显升高(χ^2=34.103、27.642,P值均<0.01);而蛋白[分别为0.62(0.34,0.93)、0.48(0.26,0.85)、0.47(0.27,0.80)g/L]、ADA[分别为2.50(1.00,5.25)、2.00(1.00,4.00)、1.00(1.00,2.00)U/L]均较入院时[分别为0.95(0.56,1.34)g/L、3.50(2.00,7.25)U/L]明显降低(χ^2=29.221、26.209,P值均<0.01)。从治疗过程看,相较于入院时的各项指标,治疗1周后各项指标均无明显变化(t=0.609、0.565、0.228、0.359,P值均>0.05);治疗2周后的各项指标开始有明显变化(t=1.076、1.239、0.946、0.761,P值均<0.05);在治疗4周时,各项指标水平也明显高于入院时(t=1.489、1.152、1.261、1.228,P值均<0.01),但与治疗第2周时的氯化物、蛋白、葡萄糖、ADA指标水平差异均无统计学意义(t值分别为0.413、0.087、0.315、0.467,P值均>0.05)。相较于治疗1周时的各项指标,治疗4周时的葡萄糖和氯化物明显增高(t=1.033,P=0.001;t=0.880,P=0.006)、ADA明显降低(t=0.870,P=0.007),而蛋白无明显变化(t=0.587,P=0.175)。结论脑脊液ADA水平与病情严重程度相关,动态检测脑脊液生化指标有助于评估病情变化。

Acute recurrent cerebral infarction caused by moyamoya disease complicated with adenomyosis:A case report

BACKGROUND Moyamoya disease is essentially an ischemic cerebrovascular disease.Here,we describe a case of acute recurrent cerebral infarction caused by moyamoya disease with concurrent adenomyosis which,to our knowledge,is the first in the literature.A literature review is also presented.CASE SUMMARY A 38-year-old female presented to the Research and Treatment Center of Moyamoya Disease in our hospital with"left limb weakness"as the main symptom.She was diagnosed with acute cerebral infarction and moyamoya disease through magnetic resonance imaging and digital subtraction angiography.Prior to this,she had experienced a prolonged menstrual period of one-month duration.This was investigated and adenomyosis was diagnosed.After passing the acute cerebral infarction phase,the patient underwent surgery for adenomyosis followed by combined cerebral revascularization.During the postoperative follow-up,improvements of the perfusion imaging stage and modified Rankin Scale were observed.A review of the literature showed only 16 reported cases of gynecological diseases complicated with stroke.The clinical characteristics,pathogenesis,therapeutic effects,and long-term prognosis of these cases have been studied and discussed.CONCLUSION In patients with moyamoya disease,early management of gynecological-related bleeding disorders is essential to prevent the complications of cerebral events.

Whole-genome resequencing reveals molecular imprints of anthropogenic and natural selection in wild and domesticated sheep

The abundance of domesticated sheep varieties and phenotypes is largely the result of long-term natural and artificial selection. However, there is limited information regarding the genetic mechanisms underlying phenotypic variation induced by the domestication and improvement of sheep. In this study, to explore genomic diversity and selective regions at the genome level, we sequenced the genomes of 100 sheep across 10 breeds and combined these results with publicly available genomic data from 225 individuals, including improved breeds, Chinese indigenous breeds,African indigenous breeds, and their Asian mouflon ancestor. Based on population structure, the domesticated sheep formed a monophyletic group,while the Chinese indigenous sheep showed a clear geographical distribution trend. Comparative genomic analysis of domestication identified several selective signatures, including IFI44 and IFI44L genes and PANK2 and RNF24 genes, associated with immune response and visual function.Population genomic analysis of improvement demonstrated that candidate genes of selected regions were mainly associated with pigmentation,energy metabolism, and growth development.Furthermore, the IFI44 and IFI44L genes showed a common selection signature in the genomes of 30domesticated sheep breeds. The IFI44 c. 54413058C>G mutation was selected for genotyping and population genetic validation. Results showed that the IFI44 polymorphism was significantly associated with partial immune traits. Our findings identified the population genetic basis of domesticated sheep at the whole-genome level, providing theoretical insights into the molecular mechanism underlying breed characteristics and phenotypic changes during sheep domestication and improvement.

Perioperative management by WeChat under the haze of COVID-19

Dear Editor,We come up with an e-health perioperative management strategy based on We Chat during the outbreak of COVID-19.The novel coronavirus pneumonia called coronavirus disease 2019(COVID-19)was of clustering onset and able to cause severe and even fatal respiratory diseases such as acute respiratory distress syndrome[1].

Quantitative coherence analysis of dual phase grating x-ray interferometry with source grating

Dual phase grating x-ray interferometry is compatible with common imaging detectors,and abandons the use of an absorption analyzer grating to reduce the radiation dose.When using x-ray tubes,an absorbing source grating must be introduced into the dual phase grating interferometer.In order to attain a high fringe visibility,in this work we conduct a quantitative coherence analysis of dual phase grating interferometry to find how the source grating affects the fringe visibility.Theoretical analysis shows that with the generalized Lau condition satisfied,the fringe visibility is influenced by the duty cycle of the source grating and the transmission through the grating bar.And the influence of the source grating profile on the fringe visibility is independent of the phase grating type.Numerical results illustrate that the maximum achievable fringe visibility decreases significantly with increasing transmission in the grating bar.Under a given transmission,one can always find an optimal duty cycle to maximize the fringe visibility.These results can be used as general guidelines for designing and optimizing dual phase grating x-ray interferometers for potential applications.

Retrieval of multiple scattering contrast from x-ray analyzer-based imaging

We present a moment-based alternative approach to retrieve multiple scattering contrasts from x-ray analyzer-based imaging. By use of the properties of moments of convolutions, the multiple-image radiography approach is theoretically validated. Furthermore, higher order moments of the object scattering distribution, inaccessible in multiple-image radiography, are simultaneously provided by this alternative approach. It is experimentally demonstrated that the skew and kurtosis information related to the distribution of sub-pixel features within the object can be obtained from those complementary contrasts. Finally, the sensitivity of the retrieved multiple scattering contrasts is investigated experimentally. The finding that the sensitivity is inversely proportional to the square root of the detected photon number essentially indicates that the retrieval of moments with an order higher than two can be achieved without increasing exposure time or dose. The presented alternative approach provides an access to the exploitation of multiple scattering contrasts, which is expected to be useful in biomedical research, materials science, security screening, etc.

Vertical two-dimensional WS_(2)flakes grown on flexible CNT film for excellent electrochemical performance

Soft electrochemical actuators that can generate mechanical motions in response to electrical stimuli can be used as artificial muscles in microscale robots.The electrode materials are the key component of the electrochemical actuator because they limit the ion diffusion and accumulation processes and thus affect the deformation in fast response-time and potential engineering applications.Low-dimensional materials,such as one-dimensional(1D)CNT and two-dimensional(2D)vertically stood WS_(2),are great electrode due to their good electrochemical stability and high surface-to-volume ratios,but show limited performances when being used on their own in the actuators because of low reconstruction or low conductivity.A combination of 1D CNT and 2D WS_(2)could form a heterojunction with both high electrochemical activity and great mechanical stability.Herein,by depositing highly disordered graphene nanosheets(HDGNs)on CNT films and then WS_(2)on the formed low-dimensional nanocarbon film,a hybrid WS_(2)/HDGN/CNT film was synthesized through a multistep CVD method.Vertically grown WS_(2)nanosheets were achieved by taking advantage of HDGNs which limits CNTs sliding.So,the volume expansion caused by the transition from WO_(3)to WS-2can force the vertical growth of WS_(2).This hybrid film shows excellent electrochemical properties,such as high specific capacitance and high rate performance.Soft actuators based on the WS_(2)/HDGN/CNT films show good actuating performance,including stability and reconfigurability.

Bio-based and Biodegradable Electrospun Fibers Composed of Poly(L-lactide) and Polyamide 4

Novel bio-based and biodegradable block copolymers were synthesized by "click" reaction between poly(L-lactide)(PLLA) and polyamide 4(PA4). Upon tuning the molar mass of PLLA block, the properties of copolymers and electrospun ultrafine fibers were investigated and compared with those of PLLA and PA4 blends. PLLA and PA4 were found incompatible and formed individual crystalline regions, along with reciprocal inhibition in crystallization. Electrospun fibers were highly hydrophobic, even if hydrophilic PA4 was the rich component. The crystallinity of either PLLA or PA4 decreased after electrospinning and PLLA-rich as-spun fibers were almost amorphous. Immersion tests proved that fibers of block copolymers were relatively homogeneous with micro-phase separation between PLLA and PA4. The fibrous structures of copolymers were different from those of the fibers electrospun from blends, for which sheath-core structure induced by macro-phase separation between homopolymers of PLLA and PA4 was confirmed by TEM, EDS, and XPS.

Molecular Genetic Variation in a Clonal Plant Population of Leymus chinensis （Trin.） Tzvel.

Randomly amplified polymorphic DNA （RAPD） analysis was used to investigate the genetic variation among populations, between populations, and within populations, relationships between genetic distance and geographic distance, and the molecular variation and population size. The effects of geographic and genetic distances, as well as of genetic differentiation and population size, on genetic variations of Leymus chinensis （Trin.） Tzvel. are discussed. The present study showed that there was significant RAPD variation between the Baicheng region population and the Daqing region population, with a molecular variance of 6.35% （P 〈 0.04）, and for differentiation among area populations of the Daqing region, with a molecular variance of 8.78% （P 〈 0.002）. A 21.06% RAPD variation among all 16 populations among two regions was found （P 〈 0.001）, as well as 72.59% variation within populations （P 〈 0.001）. Molecular variation within populations was significantly different among 16 populations.

Design, Synthesis and Biological Evaluation of Novel α-Acyloxycarboxamide-Based Derivatives as c-Met Inhibitors

Dysregulated HGF/c-Met signalling has been associated with many human cancers,poor clinical outcomes,and even resistance acquisition to some approved targeted therapies.As such,c-Met kinase has emerged as an attractive target for anticancer drug discovery.