Role of short-wavelength filtering lenses in delaying myopia progression and amelioration of asthenopia in juveniles

AIM： To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles. METHODS： Sixty ametropia juveniles （aged range, 11-15y） were randomized into two groups： the test group （30 children, 60 eyes）, wearing blue-violet light filtering lenses; and the control group （30 children, 60 eyes）, wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year, the patients underwent contrast sensitivity （glare and non-glare under bright and dark conditions）, accommodation-related testing, asthenopia questionnaire assessment, and adverse reaction questionnaire assessment. RESULTS： After ly of wearing the filtering lenses, changes in refractive power and axial length were not significantly different between the two groups （P〉0.05）. Under bright conditions, the contrast sensitivities at low and medium- frequency grating （vision angles of 6.3, 4.0, and 2.5） with glare in the test group were significantly higher than in the control group （P〈0.05）, while the contrast sensitivity at low-frequency grating （vision angles of 6.3 and 4.0） in the absence of glare in the test group was higher than in the control group （P〈0.05）. Under glare and non-glare dark conditions, the contrast sensitivities of various frequencies in the test group did not show significant differences compared with those in the control group （P〉0.05）. In the test group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity of patients wearing glasses for 6 and 12mo were significantly elevated （P〈0.05）, while the asthenopia gratings were significantly decreased （P〈0.05）. Nevertheless, in the control group,the amplitude of accommodation, accommodative lag, and accommodative sensitivity after 12mo were not significantly altered compared with baseline （P〉0.05）, and the asthenopia grating was not significantly decreased （P〉0.05）. In addition, after wearing glasses for 6 to 12mo, the asthenopia grating of patients in the test group decreased significantly compared with the control group （P〈0.05）. At 12mo, the constituent ratio of adverse reactions did not show significant difference between the two groups （P〉0.05）. CONCLUSION： A l-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses （blue/ violet-light filters） increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application. However, no significant advantages in terms of refractive power or axial length progression were found compared with ordinary aspheric lenses.

Short-wavelength infrared InAs/GaSb superlattice hole avalanche photodiode

We demonstrate two short-wavelength infrared avalanche photodiodes based on InAs/GaSb superlattice grown by metal-organic chemical vapor deposition.The difference between the two devices,namely,p+n-n+and p+nn-n+,is that the p+nn-n+device possesses an additional middle-doped layer to separate the multiplication region from the absorption region.By properly controlling the electric field distribution in the p+nn-n+device,an electric field of 906 kV/cm has been achieved,which is 2.6 times higher than that in the p+n-n+device.At a reverse bias of-0.1 V at 77 K,both devices show a 100%cut-off wavelength of 2.25μm.The p+n-n+and p+nn-n+show a dark current density of 1.5×10^-7 A/cm^2 and 1.8×10^-8 A/cm^2,and a peak responsivity about 0.35 A/W and 0.40 A/W at 1.5μm,respectively.A maximum multiplication gain of 55 is achieved in the p+nn-n+device while the value is only less than 2 in the p+n-n+device.Exponential nature of the gain characteristic as a function of reverse bias confirms a single carrier hole dominated impact ionization.

Back Illuminated N/P/P⁺Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

A bifacial silicon solar cell under monochromatic illumination in frequency modulation by the rear side is being studied for the optimization of base thickness. The density of photogenerated carriers in the base is obtained by resolution of the continuity equation, with the help of boundary conditions at the junction surface (n+/p) and the rear face (p/p+) of the base. For a short wavelength corresponding to a high absorption coefficient, the AC photocurrent density is calculated and represented according to the excess minority carrier’s recombination velocity at the junction, for different modulation frequency values. The expression of the AC recombination velocity of excess minority carriers at the rear surface of the base of the solar cell is then deduced, depending on both, the absorption coefficient of the silicon material and the thickness of the base. Compared to the intrinsic AC recombination velocity, the optimal thickness is extracted and modeled in a mathematical relationship, as a decreasing function of the modulated frequency of back illumination. Thus under these operating conditions, a maximum short-circuit photocurrent is obtained and a low-cost bifacial solar cell can be achieved by reducing material (Si) to elaborate the base thickness.

Miniaturized short-wavelength infrared spectrometer for diffuse light applications

A miniaturized short-wavelength infrared spectrometer for use with diffuse light was created by combining a thin form factor carbon nanotube composite collimator,a linear variable filter,and an InGaAs photodiode array.The resulting spectrometer measures 3 mm×4 mm×14 mm and shows a significant improvement in resolution over a spectrometer without the collimator when used with diffuse light.Its small size and high throughput make it ideal for applications such as wearable optical sensing,where light from highly scattering tissue is measured.Plethysmographic measurements on the wrist were demonstrated,showing rapid data collection with diffuse light.

Visible-blind short-wavelength infrared photodetector with high responsivity based on hyperdoped silicon

Developing a low-cost, room-temperature operated and complementary metal-oxide-semiconductor(CMOS)compatible visible-blind short-wavelength infrared(SWIR) silicon photodetector is of interest for security,telecommunications, and environmental sensing. Here, we present a silver-supersaturated silicon(Si:Ag)-based photodetector that exhibits a visible-blind and highly enhanced sub-bandgap photoresponse. The visible-blind response is caused by the strong surface-recombination-induced quenching of charge collection for short-wavelength excitation, and the enhanced sub-bandgap response is attributed to the deep-level electrontraps-induced band-bending and two-stage carrier excitation. The responsivity of the Si:Ag photodetector reaches 504 mA · W^(-1) at 1310 nm and 65 m A · W^(-1) at 1550 nm under-3 V bias, which stands on the stage as the highest level in the hyperdoped silicon devices previously reported. The high performance and mechanism understanding clearly demonstrate that the hyperdoped silicon shows great potential for use in optical interconnect and power-monitoring applications.

Short-wavelength light induces broiler’s behavioral and physiological syndrome through a misaligned eating rhythm

Previous work shows that long-wavelength light has a robust circadian rhythmic pattern in the expression of clock genes of chickens,whereas short-wavelength light leads to an arrhythmic oscillation of some clock genes(e.g.,cClock,cCry1,cCry2,cPer2,and cPer3).However,knowledge about the consequences of LED lights on the physiological and behavioral phenotype was still not clear.This experiment hypothesize that short-wavelength light disturbs chicken’s eating rhythm and leads to a wrong time to eat,resulting in metabolic syndrome.“Meihuang”broilers were housed in monochromatic LED blue light,green light,yellow light,red light,or white light with a very low dose(15 lx).Multiply physiological parameters were measured and the 24-h eating behavior was determined.The effects of LED light on physiological status and behavioral phenotype showed a wavelength-dependent manner.Short-wavelength light significantly decreased the level of total triglycerides and total cholesterol but increased triiodothyronine concentration.Inversely,long-wavelength light increased the triglycerides and total cholesterol and reduced the level of triiodothyronine.Further,it was found that short-wavelength light significantly boosted body weight compared with long-wavelength light,despite equivalent levels of food intake.Short-wavelength light induced 23.4%and 14.1%of food consumption during subjective nights,but long-wavelength light did not.These results imply that when chickens eat mattered,not just what they eat.Thus,low as 15 lx of blue light exposure during the typical dark period is sufficient to leads an individual to eat at“wrong”time,causing metabolic dysfunction.

Anisotropic Short-Wavelength Friedel Oscillation with Adjustable Envelope in Graphene

We investigate theoretically the intervalley charge density oscillation and the screened ionic potential in graphene caused by the intervalley scattering. We demonstrate that the contribution from the intervalley scattering is comparable with that from the intravalley scattering, and oscillation rather than decaying dominates at a large distance away from the external impurity. We show that the intervalley oscillation is strongly anisotropic because of the inequivalency between neighboring valleys. The anisotropic oscillation consists of an anisotropic short-wavelength oscillation with an anisotropic fixed wavelength and an isotropic long-wavelength envelop with an isotropic wavelength modulated by doping, making an adjustable-widthed wave-packet propagation. One weakens the screening and gets anisotropic short-wavelength oscillation by introducing short-range mechanism in graphene and graphene-like materials.

Exact solutions of dispersion equation for MHD waves with short-wavelength modification

Dispersive magnetohydrodynamic (MHD) waves with short-wavelength modification have an important role in transforming energy from waves into particles.In this paper,based on the two-fluid mode,a dispersion equation,including the short-wavelength effect,and its exact solution are presented.The outcome is responsible for the short-wavelength modification versions of the three ideal MHD modes (i.e.the fast,slow and Alfve'n).The results show that the fast and Alfve'n modes are modified considerably by the shortwavelength effect mainly in the quasi-parallel and quasi-perpendicular propagation directions,respectively,while the slow mode can be affected by the short-wavelength effect in all propagation directions.On the other hand,the dispersive modification occurs primarily in the finite-β regime of 0.001 < β < 1 for the fast mode and in the high-β regime of 0.1 < β < 10 for the slow mode.For the Alfve'n mode,the dispersive modification occurs from the low-β regime of β < 0.001 through the high-β regime of β > 1.

Experimental study on the acoustic roughness spectrum of high-speed railway rails

Purpose–This study aims to investigate the acoustic roughness of rails on China’s high-speed railways,with a focus on short-wavelength irregularities(less than 80 cm),which are known to significantly contribute to noise.The goal is to develop a specific acoustic roughness spectrum tailored for China’s high-speed railway system,as no such spectrum currently exists.Design/methodology/approach–A long-term tracking study was conducted on major railway lines in China,monitoring rail roughness throughout the initial operational period and the rails’service life.Data preprocessing techniques such as peak removal and curvature correction were applied for acoustic adjustments.A spatial-wavelength domain transformation was performed,providing the distribution patterns and statistical characteristics of acoustic roughness on China’s high-speed rails.Based on these analyses,a model for constructing the acoustic roughness spectrum was developed.Findings–The study found that the acoustic roughness of China’s high-speed railway rails follows aχ2 distribution with six degrees of freedom.For wavelengths greater than 8 cm,the acoustic roughness spectrum remains below the ISO specified limits.In the wavelength range of 3.2 cm to 6.3 cm,the roughness is comparable to or within the limits specified by ISO 3095:2005 and ISO 3095:2013.However,for wavelengths shorter than 2.5 cm,the roughness exceeds ISO limits.Originality/value–This research fills the gap in the lack of a specific acoustic roughness spectrum for China’s high-speed railways.By establishing a tailored spectrum based on long-term data analysis,the findings provide valuable insights for noise control and rail maintenance in the context of China’s high-speed rail system.

Comparison study on measurement of rail weld joint between inertial reference method and multi-point chord reference method

Purpose – Straightness measurement of rail weld joint is of essential importance to railway maintenance. Dueto the lack of efficient measurement equipment, there has been limited in-depth research on rail weld joint with a5-m wavelength range, leaving a significant knowledge gap in this field.Design/methodology/approach – In this study, the authors used the well-established inertial referencemethod (IR-method), and the state-of-the-art multi-point chord reference method (MCR-method). Two methodshave been applied in different types of rail straightness measurement trollies, respectively. These instrumentswere tested in a high-speed rail section within a certain region of China. The test results were ultimatelyvalidated through using traditional straightedge and feeler gauge methods as reference data to evaluate the railweld joint straightness within the 5-m wavelength range.Findings – The research reveals that IR-method and MCR-method produce reasonably similar measurementresults for wavelengths below 1 m. However, MCR-method outperforms IR-method in terms of accuracy forwavelengths exceeding 3 m. Furthermore, it was observed that IR-method, while operating at a slower speed,carries the risk of derailing and is incapable of detecting rail weld joints and low joints within the track.Originality/value – The research compare two methods’ measurement effects in a longer wavelength rangeand demonstrate the superiority of MCR-method.

基于3m波长地铁钢轨焊缝接头不平顺的轮轨响应分析

相对于1 m弦测值的焊缝接头动力学评估与管理,基于3 m波长范围的焊缝接头不平顺轮轨响应分析对其服役状态评估与管理具有重要意义。首先,基于车辆-轨道垂向耦合动力学理论建立车辆-轨道垂向耦合模型;然后,借助基于一弦N点弦测法研制的钢轨短波不平顺测量小车,对地铁线路焊缝接头不平顺进行精确测量,并根据传统弦测理论得到1 m弦测值;接着,将实测3 m波长焊缝接头不平顺和1 m弦测值作为车辆-轨道垂向耦合模型的不平顺激励输入,对比3 m波长焊缝接头不平顺和1 m弦测值激扰下的轮轨响应;最后,研究了车速和焊缝位置对轮轨动力响应的影响。结果表明:相比1 m弦测值激扰下的轮轨动力响应结果,3 m波长焊缝接头不平顺激扰下的轮轨力幅值变化不明显,轮重减载率幅值增大11.52%,钢轨加速度幅值增大54.05%,轮对振动加速度幅值增大37.67%;车速提高会导致轮轨力和轮重减载率幅值增大;焊缝中心与轨枕间的距离增加,轮轨力幅值先增加后减小,当焊缝中心距离轨枕0.1 m时,轮轨力幅值最大。

短波紫外线辐照坛紫菜壳孢子制备色彩突变体的新途径

壳孢子萌发时期是坛紫菜(Pyropia haitanensis)减数分裂发生的时期,壳孢子萌发形成的最初4个细胞呈线性排列,形成减数分裂四分体,且发生遗传重组的四分体细胞可以决定叶状体的发育模式和性状分离。因此,诱变产生色彩突变的嵌合叶状体相比诱变叶状体产生的点状色块,将更易于获得突变细胞。本研究为获得坛紫菜人工色彩嵌合突变体,使用不同剂量(50、100、200、300、400、500和600J/m^(2))的短波紫外线(UV-C,λ=254nm)辐照坛紫菜壳孢子,培养数天后,在壳孢子苗中出现了色彩突变的嵌合叶状体。结果显示,低剂量(50 J/m^(2))的辐射促进壳孢子萌发,而辐照剂量高于100 J/m^(2)则会抑制壳孢子萌发和分裂。辐照剂量在50~400J/m^(2)范围内,色彩突变体出现的频率随辐照剂量的增加而增加,辐照剂量分别为300和400J/m^(2)时,突变率分别达到15.22%和17.18%。其中,出现色彩突变的嵌合叶状体以2色块嵌合体和3色块嵌合体居多,4色块嵌合体最少,但辐照剂量增加至400 J/m^(2)以上时,随着辐照剂量的增加,色彩突变体出现的频率反而下降,表明最适宜的诱变剂量为300或400 J/m^(2)。同时,短波紫外线辐照也使色彩突变嵌合体的长宽比下降,采用生物酶解法从色彩嵌合体中分离出了单色的体细胞萌发体。本研究为坛紫菜人工色彩突变体的制备和诱变育种提供了新途径。

融合轨面短波不平顺的全波段高低不平顺谱表征及影响分析

轨道不平顺谱是表征轨道不平顺幅频特性的有效工具。目前,高速铁路轨道不平顺谱的研究主要聚焦在波长2 m及以上成分,甚少涉及轨面短波不平顺谱。基于大量无砟轨道高速铁路实测数据,研究轨面短波不平顺谱的表达函数及其与中长波轨道不平顺谱衔接的适应性。结果表明:两段幂函数能够很好地表征轨面短波不平顺谱。采用对数坐标系下的5阶多项式拟合全波段高低不平顺谱,实现中长波和短波成分在波长1~2 m范围内的平缓过渡。实测数据表明高速行车条件下,短波高低不平顺对轮轨垂向力及轴箱、构架和车体垂向加速度等指标均存在显著影响,全波段高低不平顺谱的建立对轮轨振动仿真分析、车辆和轨道结构设计以及轨道状态评估具有重要意义。

更快速度下周期性短波不平顺引起的轮轨高频振动特性及控制限值

随着列车运行速度的不断加快,轮轨高频振动引起的车辆、轨道部件伤损问题更加突出,尤以周期性的短波不平顺最为常见。为了掌握轮轨高频振动自下而上的传递衰减规律以及制定合理的钢轨打磨策略,有必要针对车辆系统在高频激励条件下的耦合振动特性开展深入的理论研究。本文通过对大量实测数据的拟合,得到了更宽频段范围内的轨道高低不平顺谱拟合公式,并通过反演得到了0.002~100 m波长范围内的高低不平顺样本;在此基础上建立了高速动车组-轨道刚柔耦合动力学模型,其中对轮对、钢轨均考虑了弹性体振动模态,仿真分析了周期性短波不平顺引起的轮轨高频振动特性。结果表明,车辆各部件的振动频率分布范围为30~1390 Hz,且自下至上呈逐层衰减趋势。通过提取周期性短波不平顺幅值变化对轮轨相互作用的影响规律,进一步提出了适应400 km/h高速铁路的典型波长周期性短波不平顺的量化控制限值要求。

短波不平顺引起轮轨激振的中高频垂向力研究

为研究普通列车轨道不平顺对轮轨激振力的影响,采用LS-DYNA软件建立三维有限元轮轨耦合力学模型。该模型把车轮简化为质量点,轨道简化为梁,利用RAIL_TRAIN和RAIL_TRACK模块实现轮轨的耦合。利用该模型,分析不同车速、不同波长和幅值所表征的轨道不平顺引起的列车轮轨垂向力及其变化特点,并研究影响垂向力的敏感因素。结果表明:车速越低,不平顺波的幅值对轮轨垂向力的影响越大;相同的车速和不平顺波长,不平顺波的幅值越大,垂向力也越大,且垂向力和不平顺波的幅值近似呈线性关系;不同车速下,轨道不平顺的敏感波长不同,但其车速与敏感波长之比的频率均约为300 Hz,接近轨道的291.949 Hz(45阶模态频率)。

短波近红外光谱法分析酒中乙醇含量

使用短波近红外光谱和多变量校正技术快速准确地测定酒中乙醇含量.研究了纯水、乙醇以及乙醇和水混合体系的光谱特征.用多元线性回归(MLR)和主成分回归(PCR)分析了二阶导数差谱数据.该法分析酒样具有方便、快速的优点.

短波红外光谱技术在浅剥蚀斑岩铜矿区勘查中的应用——以西藏念村矿区为例

作为世界上最重要的一种矿床类型,斑岩铜矿一直是工业界勘查的首选。对此类矿床的勘查,在中-深剥蚀程度的矿区相对简单,而在浅剥蚀的矿区则变得较为困难,这是因为在浅剥蚀的矿区,矿床热液/矿化中心很难快速有效定位。近年来,在矿产勘查领域逐渐得到广泛应用的短波红外光谱技术,可通过特定蚀变矿物反射光谱特征参数系统变化的规律来厘定热液/矿化中心,在块状硫化物及浅成低温矿床中显示出良好的应用效果,这为浅剥蚀斑岩铜矿热液/矿化中心的快速、有效厘定提供了一种途径。为此,文章选择了位于冈底斯斑岩铜矿带东段、剥蚀较弱的念村(即夏玛日)矿区,拟通过矿区样品短波红外光谱的系统测量,寻找出蚀变矿物反射光谱特征参数系统变化的规律,进而约束矿床热液/矿化中心。本次研究在念村矿区共识别出7种蚀变矿物,按出现频率由多至少依次为伊利石、绿泥石、蛋白石、叶蜡石、高岭石、绿帘石及多硅白云母;而且,矿区外围以伊利石-绿泥石±绿帘石蚀变矿物组合为主,向内逐渐过渡为伊利石±蛋白石、伊利石-叶蜡石±高岭石组合。通过对伊利石反射光谱特征参数的计算发现,伊利石结晶度及Al-OH吸收峰位,这些通常被认为与伊利石形成温度有关的光谱学参数,在该矿区呈现出系统的变化规律:在矿区东北部,伊利石结晶度较大(>1.6),Al-OH吸收峰位较小(<2203nm),而该区域的外围,伊利石结晶度变小,Al-OH吸收峰位变大。这表明矿区东北部伊利石的形成温度更高,暗示该区域可能为矿床热液/矿化中心。因此,建议在本次研究所圈定的热液/矿化中心范围内,在适当开展物探工作的基础上,尽快布置勘查工程进行验证,以实现矿床的尽快查找和突破。

超声处理对中短波红外干燥红枣时间及品质的影响

为提高红枣干燥品质,减少干燥时间,以干燥时间为响应值,响应面优化得到红枣中短波红外干燥前超声处理条件为:频率40 k Hz、时间40 min、功率350 W。最优超声处理后中短波红外干燥红枣至其干基含水率约为40%时所需干燥时间为9.55 h;未超声处理中短波红外干燥需13.33 h;传统热风干燥需17.13 h。扫描电镜观察红枣果皮,超声处理40 min使果皮表面产生大量裂缝,表皮层变薄,仅38.8μm,表皮层和亚表皮层易分离,利于干燥过程中水分扩散,显著缩短中短波红外干燥时间。红枣超声处理后中短波红外干燥的干制品品质显著优于未超声处理红外干燥,极显著优于传统热风干燥。最优超声处理条件结合中短波红外干燥,所得干制品在3种处理方式中总VC、总酚、总黄酮含量最高,糖酸比最高,色泽最优,能耗最少,是适合红枣干燥的技术方法。

InGaAs近红外线列焦面阵的研制进展

研制出光谱响应为0.9～1.7μm的256×1、512×1元InGaAs线列焦平面组件,和光谱响应延展至2.4μm的256×1元InGaAs线列焦平面组件。焦平面组件包括光敏芯片、读出电路、热电制冷器以及管壳封装。光敏芯片在InP/InGaAs/InP(p-i-n)双异质结外延材料上采用台面结构实现,并与128×1或512×1元CTIA结构的读出电路耦合。焦平面器件置于双列直插金属管壳中,采用平行缝焊的方式进行封装。介绍了高均匀性长线列InGaAs焦平面组件的关键技术和主要性能结果,为更长线列焦平面组件的研制提供了坚实的基础。

短波红外InGaAs/InP光伏探测器系列的研制

采用气态源分子束外延方法及应用有源区同质结构及较薄的组分渐变InxGa1-xAs缓冲层,研制了波长扩展的InGaAs/InP光伏探测器系列,其室温下的截止波长分别约为1.9μm,2.2μm.和2.5μm.对此探测器系列在较宽温度范围内的性能进行了细致表征,结果表明在室温下其R0A乘积分别为765,10.3和12.7Ωcm2,比室温降低100K时其暗电流和R0A可改善约3个量级.瞬态特性测量表明此探测器系列适合高速工作,实测响应速度已达数十ps量级.