Progress on research and mitigation of wind-blown sand risk in Dunhuang Singing Sand Mountain and Crescent Spring Scenic area,China

The Singing Sand Mountain and Crescent Spring Scenic Spot in Dunhuang,Northwest China is a world-renowned desert attraction that is also an integral component of the Dunhuang UNESCO Global Geopark.This scenic area underwent a 30-year transformation,i.e.,from a severe sand risk with spring water threatened by sand burial due to dune deformation,to restoration of the original sand flow field and mitigation of the sand burial problem.The current paper summarizes the research on the intensive monitoring of the dynamic change of star dunes near the spring,observation of wind and sand flow movement,and then restoring the harmonic vibration of the sand particles(singing sand)that were previously silenced.The existing and prospective impacts of anthropogenic and natural forces on the deformation of the sand dunes are investigated by integrated methods,guiding the implementation of mitigating measures with significant ameliorative effects.Contrast to common sand control practices that aim to reduce wind speed and stop blown sands,our research highlights the importance of maintaining the natural wind flow field in stabilizing surrounding dunes.These mitigation measures consist of removing excessive vegetation and newly constructed buildings to recover the original wind flow field and sand transport activity.Such research and mitigation efforts ensure the scientific protection and restoration of the special desert landform,and contribute to the mutual enhancement of the conservation and exploitation of this desert scenic spot and similar sites.

Quantitative analysis on the dynamic characteristics of megadunes around the Crescent Moon Spring, China

The Crescent Moon Spring is a precious natural heritage. However, the dynamic characteristics of megadunes around the Crescent Moon Spring are not well known. This paper quantitatively studied the character- istics and changes of megadunes around the Crescent Moon Spring by interpreting aerial photographs taken in 1985 and 2004 and analysing the dune crestlines and the wind data collected from 2011 to 2012. Results revealed that pyramid dunes were formed by a complex wind regime. The Crescent Moon Spring was not buried by shifting sands because of the stable wind regime and relative stability of pyramid dunes. The crestlines of the dunes around the spring moved northward between 1985 and 2004. The south-facing slip faces were also exposed to wind ero- sion, whereas the other faces were under deposition, thus indicating that the southerly wind was relatively en- hanced. Limiting the scale of tall windbreaks and architectures in the Dunhuang oasis at the north of the spring was necessary to maintain the dynamic equilibrium of the wind regime and sand transport.

Morphological variation of star dune and implications for dune management: a case study at the Crescent Moon Spring scenic spot of Dunhuang, China

Aerial photographs and 3-D laser scans of a 90-m high star dune at the Crescent Moon Spring scenic spot in Dunhuang,China,are used to investigate the changes in dune morphology on timescales from months to decades.The result revealed that relative-equilibrium airflow strength in three wind directions of northeast,west and south was an important condition for the stability of star dunes with limited migration.Transverse and longitudinal airflows exerted a crucial impact on variation processes of star dune morphology.Controlled by transverse airflows,the easterly winds,the east side was dominated by wind erosion;and strong deposition occurred on the south-south-east arm with a maximum deposition rate of 0.44 m/a in the 46-a monitoring period,causing the east side becoming steep and high.Controlled by longitudinal airflows,the westerly winds,the west-north-west side was mainly eroded and the north arm migrated from west to east with a rate of 0.30 m/a,causing the dune slope becoming gentle and elongate.The local air circulation(southerly winds)exerted a significant impact on the development process of the star dune.Due to the influence of human activities,the south side present surface processes from a concave profile to a convex profile in 46 a,which is a potential threat to the Crescent Moon Spring.The results indicate that rehabilitating the airflow field at most is a crucial strategy to the protection of Crescent Moon Spring from burial.Opening up the passage of easterly,westerly and southerly winds through intermediately cutting the protection forest,demolishing the enclosed wall and changing the pavilion into a porous pattern have been suggested to protect the Crescent Moon Spring from burial.

Experimental study on modulational instability and evolution of crescent waves

A series of experiments on the instability of steeP water wave trains in water with finite water depths and infinite water depths in a wide wave basin were performed. It was found that under the coupled development of modulational instability and class-Ⅱ instability, the initial two-dimensional steep wave trains evolved into three＇dimensional crescent waves, followed by the occurrence of disordered water surfaces, and that the wave energy transferred to sidebands in the amplitude spectrum of the water surface elevation. The results also show that water depth has a significant effect on the growth of modulational instability and the evolutiin of crescent waves. The larger the water depth, the more quickly the modulational instability suppresses class-II instability.

Bacterial diversity in the sediment of Crescent Moon Spring,Kumtag Desert,Northwest China

Desert lake, a unique oasis in desert ecosystems, harbours different bacterial communities. Thus, it is considered as a hub of bacterial diversity. In this study, bacterial diversity in the sediment of Crescent Moon Spring, Kumtag Desert, Northwest China was analyzed using high-throughput amplicon pyrosequencing analysis. The sequences of the most abundant OUTs （Operational Taxonomic Units） in the sediment of Crescent Moon Spring were compared with the sequences of those most abundant OUTs of various origins from NCBI GenBank database to detect the origins of bacteria in the sediment of Crescent Moon Spring. Also, bacterial compositions between sediment of Crescent Moon Spring and other desert and lake ecosystems （including desert lakes） worldwide were compared using cluster analysis to determine the possible factors affecting bacterial compositions. In total, 11,855 sequences were obtained and 30 phyla were identified. At the phylum level, the dominant phylum was Proteobacteria with α-Proteobacteria being the first dominant class and the second dominant phylum was Planctomycetes. Our finding that α-Proteobacteria being the first dominant class of Proteobacteria and Planctomycetes being the second dominant phyla are somewhat contradictory with reports from other desert lake sediments. This difference could be resulted from water hydration and conductivity, as well as oligotrophic conditions of Crescent Moon Spring. At the genus level, Rhodobacter, Caldilinea, Planctomyces, and Porphyrobacterwere the dominant genera in the sediment of Crescent Moon Spring. Comparisons on sequences of the most abundant OUTs （including OTU3615, OTU6535, and OTU6646） between sediment of Crescent Moon Spring and various origins from NCBI GenBank database indicate that the origins of bacteria in the sediment of Crescent Moon Spring are likely from the underground water. Furthermore, cluster analysis on comparisons of bacteria compositions between sediment of Crescent Moon Spring and other desert and lake ecosystems （including desert lakes） worldwide shows that at regional scales, bacterial compositions may be mainly affected by geographical patterns, precipitation amounts, and pH values. Collectively, our results provide new knowledge on the bacterial diversity in desert lake ecosystems.

Grain size distribution at four developmental stages of crescent dunes in the hinterland of the Taklimakan Desert,China

Although scientists have performed many studies on crescent （barchan） dunes in the Taklimakan Desert,few studies reported the changes in grain size at different development stages of crescent dunes.In order to evaluate the changing trends of surface sediment grain size with dune development,we investigated the grain size characteristics at four developmental stages （oval sand pile,shield dune,incipient crescent dune and mature crescent dune） of crescent dunes by measuring the morphology of sand dune and observing the near-surface wind regime.The dunes have developed in a wide inter-dune corridor between high compound longitudinal ridges in China＇s Taklimakan Desert.The surface sediments at four developmental stages of the crescent dunes were primarily composed of fine sands,followed by very fine and medium sands.Mean grain sizes ranged from 2.8 to 3.1 φ,with a unimodal distribution.The sands were moderately well-sorted,their distribution varied from platykurtic to very platykurtic,and symmetrical or skewed towards the fine particles.From oval sand piles through shield and incipient crescent dunes to mature crescent dunes,incipient grain size gradually increased,particles became finer,sorting became better,kurtosis and skewness increased.Grain sizes on the surface layer became coarser upwards from the toe of the windward slope and then became finer towards the bottom of the leeward slope.We found that the coarsest particles at different positions at the four developmental stages were different.The coarsest particles were distributed at the top of the oval sand piles and shield dunes,versus at the middle of the windward slope of the incipient and mature crescent dunes.Correlations between the mean grain size and other grain size parameters showed that as mean grain size became finer,sorting became better and kurtosis became wider,but skewness changed only slightly.In addition,grain size variation in the surface sediments correlated with the movement speed of the dunes in the study area.In the open ground among tall-complex longitudinal ridges in the hinterland of the Taklimakan Desert where aeolian environment is characterized by comparatively strong wind and unsaturated sand flow,faster dune movement corresponded to coarser grain size.

Antineutrophil cytoplasmic antibodies crescentic allograft glomerulonephritis after sofosbuvir therapy

Antineutrophil cytoplasmic antibodies(ANCA) are well known to be associated with several types of vasculitis, including pauci-immune crescentic glomerulonephritis, a form of rapid progressive glomerular nephritis(RPGN). ANCA vasculitis has also been reported after administration of propylthiouracil, hydralazine, cocaine(adulterated with levimasole), allopurinol, penicillamine and few other drugs. All previously reported cases of drug-associated ANCA glomerulonephritis were in native kidneys. Sofosbuvir is a new and effective drug for hepatitis C virus infection. Here, we report a case of ANCA vasculitis and RPGN following sofosbuvir administration in a kidney transplant recipient. It also represents the first case of drug-associated ANCA vasculitis in a transplanted kidney. Further drug monitoring is necessary to elucidate the degree of association and possible causal effect of sofosbuvir and perinuclear ANCA vasculitis.

Accuracy of crescent sign on ocular ultrasound in diagnosing papilledema

AIM To study the usefulness of orbital ultrasonography in the diagnosis of papilledema.METHODS Fifty patients who were referred to the neurophthalmology clinic and clinically suspected to have papilledema were selected. Thorough, clinical examination with slitlamp biomicroscopy and visual acuity assessment was done. These patients underwent ultrasonography to demonstrate the crescent sign. The patients were further evaluated with the neurologist and magnetic resonance imaging(MRI) thus confirming the diagnosis of papilledema. The results of our ultrasonographic evaluation were correlated with final diagnosis after thorough clinical evaluation, imaging and the neurologist's opinion.RESULTS Out of 50 patients diagnosed having papilledema on MRI, 46(92%) showed crescent sign on B scan ultrasonography. Headache was most common presenting complaint in 47(94%) and idiopathic intracranial hypertension was most common underlying cause of papilledema in 30(60%) cases.CONCLUSION"Crescent sign" seen on ultrasonography is a sensitive tool for diagnosis of papilledema. It is cost effective, less cumbersome and effective tool to differentiatebetween papilledema and pseudo papilledema before subjecting the patients to costly investigations like MRI. A positive crescent sign should always be followed by MRI to find out the cause of papilledema.

Evolution of crescent-shaped sand dune under the influence of injected sand flux:scaling law and wind tunnel experiment

This paper studies the evolution of crescent-shaped dune under the influence of injected flux. A scaling law and a wind tunnel experiment are carried out for comparison. The experiment incorporates a novel image processing algorithm to recover the evolutionary process. The theoretical and experimental results agree well in the middle stage of dune evolution, but deviate from each other in the initial and final stages, suggesting that the crescent-shaped dune evolution is intrinsically scale-variant and that the crescent shape breaks down under unsaturated condition.

A Restrained Iran:Consolidating the Shiite Crescent

The Arab Spring is supposed to be the Arab world’s great changes and turmoil,but Iran has repeatedly become the focus in the following changes.Whether it is in the Syrian civil war,or strikes against ISIS,or the Qatar crisis,Iran repeatedly appeared.There are different attitudes towards Iran’s behavior.The Trump administration holds the opinion that Iran is

Two Cases of ANCA-negative Pauci-immune Crescentic Glomerulonephritis in Pregnant or Maternal Women

Here two cases of renal failure occurring in pregnancy were reported,with biopsy-proven pauci-immune crescentic glomerulonephritis at postpartum.It is most rare that pauci-immune crescentic glomerulonephritis as the cause of renal failure in pregnancy.Their renal function could remain stable for some time due to timely and appropriate treatment.Therefore,the pregnant and maternal who have the performance of renal impairment should be closely tracked their blood pressure,urinary protein and renal function,if necessary,execute renal biopsy,for a clear and accurate pathological diagnosis is of great significance to grasp the opportunity of treatment.But the long-term prognosis is still poor.

The clinical and pathological characteristics of Chinese patients with pauci-immune crescent glomerulonephritis

目的 对寡免疫复合物型新月体肾炎进行临床病理分析。方法 采用病理检查包括 :光镜检查、免疫病理分析、血清学检查、肾功能检查以及统计学分析。结果 6 4 0 0例非移植肾活检中发现 2 4例寡免疫复合物型新月体肾炎 (PICGN)患者 ,占肾活检总数的 0 37% ,占新月体肾炎总数的 2 3 9% ,其中女性 16例 ,男性 8例 ,平均年龄 33岁。血管炎中微型多动脉炎 (33 3% )和结节性多动脉炎 (8 3% )为常见继发病因。抗中性粒细胞胞浆抗体 (ANCA)阳性率为 52 2 %。临床上多表现为急进性肾功能减退 (75 0 % ) ,发作性肉眼血尿发生率高 (58 3% ) ,高血压发生率为 4 5 8% ,肾病综合症发生率为 4 1 7% ,2 5%患者出现少尿无尿症状。除贫血外 ,肾外表现较少。病理上血管襻坏死 (6 2 5% )、单核及中性粒细胞浸润(6 6 7% )及小血管炎等为常见的急性病变 ;然而 ,小球硬化 (4 5 8% )、小管萎缩 (83 3% )、间质纤维化 (75 0 % )等慢性化病变也较严重。 2 2例患者行免疫抑制治疗 ,16例随访 8— 92个月 ,有 4例肾功能在正常范围 (<12 4 μmol/L) ,8例行非透析保守治疗 ,仅 4例进入终末期肾功能衰竭需进行维持性血透析治疗。结论 免疫抑制冲击治疗是治疗PICGN的有效方法。

表现为新月体性肾小球肾炎的纤维性肾小球病

34岁女性患者,临床表现为水肿、高血压、大量蛋白尿、镜下血尿、低蛋白血症、血清肌酐升高。肾活检病理光镜示大量新月体形成伴袢坏死,电镜示上皮下、基膜内及系膜区杂乱分布的纤维样结构(直径12~30 nm)沉积,肾小球免疫组化染色DNAJ热休克蛋白家族成员B9(DNAJB9)阳性,诊断为DNAJB9相关纤维性肾小球病、新月体性肾小球肾炎。给予利妥昔单抗、吗替麦考酚酯、糖皮质激素等治疗,获得了较好的临床疗效。

The distribution and significance of renal infiltrating cells in patients with diffuse crescentic glomerulonephritis

Objective To study the significance and distribution of renal infiltrating cells, including monocytes (CD68+ cells), proliferative cell nuclear antigen positive cells (PCNA+ cells), CD4+ and CD8+ cells in diffuse crescent glomerulonephritis (DCGN). Methods Fifty-six patients with DCGN were studied, including 10 cases of anti-glomerular basement membrane (GBM)-type Ⅰ DCGN, 26 immune complex-type Ⅱ DCGN, and 20 cases of pauci-immune-type Ⅲ DCGN. Glomerular and interstitial infiltrates of CD68+ and PCNA+ cells, and interstitial infiltrates of CD4+ and CD8+ cells were detected by using four-layer PAP methods. Results There was a significant increase of renal infiltrating CD68+, PCNA+, CD4+ and CD8+ cells in patients with DCGN compared with that in normal controls. In patients with type Ⅰ DCGN, there was a higher number of renal infiltrating CD68+ and PCNA+ cells than that in patients with type Ⅱ and Ⅲ DCGN. A glomerular infiltrates of CD68+ and PCNA+ cells correlated with the interstitial infiltrates of CD4+ cells in type Ⅰ or Ⅲ DCGN patients. In lupus DCGN patients, the numbers of renal infiltrating CD68+ and PCNA+ cells were similar to vasculitis or type Ⅲ DCGN patients.Conclusion These findings demonstrate that the renal infiltrates of CD68+ and PCNA+ cells play an important role in patients with DCGN, that the infiltrates of CD4+ cells correlate with the infiltrates of CD68+ and PCNA+ cells may be an active marker of DCGN, and that cell-mediated immunity may contribute to crescent formation in lupus DCGN patients.

组织工程治疗股骨头坏死软骨下分离的适用技术

背景:股骨头坏死出现新月征是病情进程的“分水岭”,修复和稳定骨-软骨界面对阻止病情继续进展和预防股骨头塌陷尤为重要。利用组织工程学同步修复、整合骨-软骨界面具有潜在优势。目的:综述探讨解决股骨头坏死软骨下分离的潜在适宜技术。方法:检索1970年1月至2023年4月PubMed、Web of Science及中国知网、万方数据库中发表的相关文献,英文检索词:“Femoral head necrosis,Avascular necrosis of femoral head,Osteonecrosis of femoral head”等,中文检索词:“股骨头坏死,软骨下骨,软骨,软骨与软骨下骨整合”等,最终纳入114篇文献进行综述分析。结果与结论:①结构缺陷、缺血缺氧环境、炎症因素和应力集中可能造成股骨头坏死软骨下分离现象,软骨下骨分离会造成塌陷进展,并且可能与保髋手术失败相关,利用组织工程支架实现支架与骨-软骨界面的整合是治疗股骨头坏死软骨下分离的潜在方法之一。②目前的文献研究表明,多相、梯度支架和复合材料在促进骨、软骨细胞黏附与增殖,骨软骨基质的沉积方面均有提升,有助于支架与骨-软骨界面的整合,对治疗股骨头坏死软骨下分离有参考价值。③通过对支架表面进行修饰可以提高与界面整合的效率,但有各自不同的优缺点,提供不同环境的支架能够诱导同种间充质干细胞差异分化,有助于不同界面之间的整合。④未来有望应用于股骨头坏死软骨下分离的支架应为复合材料,具有梯度化和差异化的仿生结构,通过表面修饰和干细胞加载促进骨-软骨界面与支架的整合以实现治疗目的,但仍需进一步研究验证,而支架的降解速率与修复进度同步和不同界面之间的稳定性是未来需要解决的主要问题。

过敏性紫癜肾炎伴新月体形成患儿的实验室指标和病理特征分析

目的研究新月体形成后过敏性紫癜肾炎(HSPN)患儿的实验室指标和病理特征的变化,并探寻预测新月体形成的无创性生物标志物。方法选取2018年1月—2023年7月住院的HSPN患儿278例,根据新月体形成情况,分为新月体形成组(196例)和无新月体形成组(82例),并将新月体根据形成类型分为细胞性新月体组(52例)和细胞纤维性新月体组(144例)。比较各组间的实验室指标和病理特征,分析各个指标与新月体形成比例间的相关性,采用Logistic回归分析新月体形成的影响因素,绘制受试者工作特征(ROC)曲线,评价实验室指标预测新月体形成的效能。结果与无新月体形成组相比,新月体形成组24 h尿蛋白定量(24 hUP)、尿免疫球蛋白G/肌酐(UGCR)、尿红细胞计数(URBC)、中性粒细胞/淋巴细胞比值(NLR)、血尿素氮(BUN)、三酰甘油(TG)明显升高,出现弥漫性系膜增生(Mb)、肾小管萎缩或间质纤维化(T1)的占比增高(均P<0.05);与细胞性新月体组相比,细胞纤维性新月体组的肾小球节段性硬化或粘连(S1)和T1的占比增高,新月体形成的比例较高,细胞性新月体组毛细血管内皮细胞增生(E1)占比降低(均P<0.05)。Spearman相关性分析显示,24 hUP、UGCR、URBC、NLR、BUN、TG、Mb及T1与新月体形成比例呈正相关(均P<0.05)。多因素Logistic回归分析结果显示,UGCR升高、T1是新月体形成的危险因素;UGCR预测新月体形成的曲线下面积(AUC)为0.731(95%CI:0.667~0.795,P<0.05),最佳截断值为5.00 mg/mmol,敏感度0.744,特异度0.610。结论UGCR可作为一种辅助评估HSPN患儿新月体形成的无创性生物标志物。

原发性IgA肾病伴弥漫性新月体形成的临床特点及预后分析

目的了解弥漫性新月体IgA肾病(CIgAN)患者的临床病理特征和预后。方法2007年7月至2022年7月经肾活检确诊为弥漫性新月体IgAN患者33例,分析临床及病理资料。随访时间超过6个月患者22例纳入随访队列。结果33例患者中男18例(55%),女15例(45%),肾活检时年龄为36(21.5,51)岁,血清肌酐(Scr)153(92,271)μmol/L,新月体百分比为62.5%(54.2%,66.7%),其中细胞纤维性新月体为(26.1%±16.5%)。13例患者有前驱呼吸道感染。22例患者平均随访时间为25(8,72)个月。10例(46%)患者进展至复合肾脏结局,其中8例(36%)发展为终末期肾脏病。多因素Cox回归结果显示,肾活检时Scr是复合肾脏结局的独立危险因素,而新月体的百分比与复合肾脏结局无关。受试者工作特征曲线结果表明,即使接受免疫抑制剂治疗,肾活检时Scr浓度大于149μmol/L的弥漫性新月体IgAN患者预后不良风险仍然较高。结论弥漫性新月体IgAN病情进展快,预后差,尤其是肾活检时Scr浓度大于149μmol/L的患者。新月体类型以细胞纤维性新月体为主。肾活检时血清Scr浓度是弥漫性新月体IgAN患者eGFR下降≥50%或ESKD的独立危险因素,而新月体的百分比与患者预后无明显相关性。

IgA肾病伴新月体形成合并肾衰竭的治疗方案比较及肾组织TWEAK的表达差异

目的:探讨糖皮质激素联合环磷酰胺的不同治疗方案对IgA肾病伴新月体形成合并肾衰竭患者的疗效和安全性及肾组织肿瘤坏死因子样凋亡微弱诱导剂(TWEAK)的表达差异。方法:将收治于我院的59位IgA肾病伴有新月体形成的肾衰竭患者根据治疗方案的不同纳入以下4组:对照组、糖皮质激素(G)组、G+环磷酰胺(C)组和G冲击+C组,观察24周各组的疗效和安全性。此外,免疫组织化学染色观察TWEAK在肾组织中的表达和分析其与临床指标的相关性。结果:G组、G+C组和G冲击+C组治疗后的24 h尿蛋白定量、血肌酐、eGFR水平均优于对照组(P<0.05)。对临床疗效进行比较,发现G组(47.06%)、G+C组(50.00%)和G冲击+C组(58.33%)总有效率均高于对照组(7.14%),差异具有统计学意义(P<0.05)。对药物安全性进行比较,3个治疗组不良反应发生率差异无统计学意义(P>0.05)。免疫组织化学分析结果显示总体有效组TWEAK表达和分布均低于无效组(P<0.05)。且TWEAK的表达量与尿红细胞数无明显相关性(P>0.05),但与尿蛋白定量、血肌酐存在正相关(P<0.05),与eGFR存在负相关(P<0.05)。结论:单用半量糖皮质激素的治疗方案是IgA肾病伴新月体形成合并肾衰竭安全有效的方案,且临床应用更具优势,并且我们发现IgA肾病患者肾组织中TWEAK的表达可能与更差的肾脏预后相关。

PCCL光束对瑞利粒子作用力的理论研究

为了探究部分相干月牙形光束(PCCL)对瑞利粒子的捕获特性,采用广义惠更斯-菲涅耳原理推导了PCCL光束经过ABCD光学系统传输后的交叉谱密度及对瑞利粒子作用力的表达式,对聚焦PCCL光束在焦平面的归一化光强和对瑞利粒子作用力的分布情况进行了软件模拟和理论分析,得到了聚焦PCCL光束的光强和捕获力随光束参量以及焦距变化的规律。结果表明,选取光束阶数n=3、初始腰宽w_(0)=0.1 mm、相干长度d_(0)=6 mm时,经焦距f=12 mm的透镜聚焦后的PCCL光束对高、低折射率粒子均能实现捕获;由于PCCL光束在焦平面处呈现离轴光强分布,峰值光强不在坐标原点,通过调节光束阶数、初始腰宽、相干长度和焦距,可实现对聚焦PCCL光强及瑞利粒子作用力的调控,从而实现聚焦PCCL光束对不同位置处瑞利粒子的灵活捕获。该研究结果为实际聚焦PCCL光束稳定捕获微粒提供了理论依据。

大型冲击式水轮机球型分岔配水机构水力特性及磨蚀预测

随着冲击式水轮机向大容量发展,配水机构的水沙气多相流特性和泥沙磨蚀受到广泛关注。为此,提出一种月牙肋球型分岔六喷嘴配水机构,采用RANS-ELES混合紊流数值模型模拟了配水机构的水力特性,水气交界面采用VOF模型进行追踪,并分析了不同肋宽比对流场和泥沙磨蚀的影响。结果表明:小肋宽比能改善配水机构射流质量,并有利于配水环管分叉部位抗泥沙磨蚀。研究成果可为类似冲击式水轮机的设计与运行提供借鉴。