Effects of low intensity laser irradiation phototherapy on dental pulp constructs

AIM: To investigate low intensity laser irradiation phototherapy(LILIP) on the proliferation, mineralization and degradation of dental pulp constructs.METHODS: Stem cells from human exfoliated deciduous teeth(SHED) were grown to confluence and seeded on collagen scaffolds to create dental pulp constructs. LILIP was delivered to the dental pulp constructs using an 830 nm GaA IAs laser at an output power of 20 m W. The LILIP energy density was 0.4, 0.8, 1.2, and 2.4 J/cm2. After 8 d, the cell proliferation and degradation within the dental pulp constructs were measured using histologic criteria. After 28 d, the effect of LILIP on SHED mineralization was assessed by von Kossa staining.RESULTS: SHED proliferation within the dental pulp constructs varied after exposure to the 0.4, 0.8, 1.2,and 2.4 J/cm2 LILIP energy densities(P < 0.05). The maximum proliferation of SHED in nutrient deficient media was 218% after exposure to a 1.2 J/cm2 LILIP energy density. SHED grown in nutrient deficient media after exposure to a 0.4, 0.8, and 1.2 J/cm2 LILIP energy density, proliferated by 167-218% compared to the untreated(non-LILIP) control group(P < 0.05).SHED exposed to a 0.4, 0.8, and 1.2 J/cm2 LILIP energy density, and grown in optimal nutritional conditions and proliferated by 147%-164% compared to the untreated(non-LILIP) control group(P < 0.05). The exposure of SHED to the highest LILIP energy density(2.4 J/cm2) caused a reduction of the cell proliferation of up to 73% of the untreated(non-LILIP) control(P < 0.05). The amount of mineral produced by SHED increased over time up to 28 d(P < 0.05). The 0.8 and 1.2J/cm2 LILIP energy densities were the most effective at stimulating the increased the mineralization of the SHED from 150%-700% compared to untreated(nonLILIP) control over 28 d(P < 0.05). The degradation of dental pulp constructs was affected by LILIP(P <0.05). The dental pulp constructs grown in optimal nutritional conditions exposed to a 0.8 J/cm2 or 1.2 J/cm2 LILIP energy density had 13% to 16% more degradation than the untreated(non-LILIP) control groups(P < 0.05). The other LILIP energy densities caused a 1%degradation of dental pulp constructs in optimal nutritional conditions(P > 0.05).CONCLUSION: LILIP can enhance or reduce SHED proliferation, degradation and mineralization within dental pulp constructs. LILIP could promote the healing and regeneration of dental tissues.

Low frequency ultrasonic multi-mode Lamb wave method for characterizing the ultra-thin transversely isotropic laminate composite: Theory and experiment

A low-frequency multi-mode ultrasonic Lamb wave method suitable for character- izing the thickness, the density and the elastic constants of the ultra-thin transversely isotropic laminate composite is presented. The 'ultra-thin' here means that the thickness of the plate is much less than the wavelength of the ultrasonic wave so that the echoes from the front and back faces of the plate can't be separated in the time domain. The dispersion equations for the low frequency ultrasonic Lamb waves with the propagation directions parallel and vertical to the fiber direction are derived. In conjunction with the least square algorithm method, the secant algorithm is used to estimate the parameters of the ultra-thin fiber-reinforced composite layer. The evaluation errors and the sensitivity of the method to different paramters of the thin composite are analyzed. The technique has been used to characterize the ultra-thin grass fiber reinforced PES composite with thickness down to ten percents of the ultrasonic wavelength. It is observed that the agreement between the nominal and the estimation values is reasonably good.

Measurement of acoustic field radiated by low frequency power ultrasonic transducer with laser-interferometer

Based on the piezo-optic effect of medium, the refractive index of medium is the function of its density, and so it's also the function of acoustic pressure. Therefore, acoustic pressure in the optical path everywhere can be determined absolutely by laser-interferometric technique and relative distribution of pressure in the middle and far acoustic field, which can be obtained from theory or experiment respectively. Theory and experiment of measurement of pressure in acoustic field with laser-interferometer are introduced. Distribution of pressure radiated by a power ultrasonic transducer is determined by laser interferometric technique. The theoretical and experimental results are in good agreement. The receiving sensitivity of a PVDF (Polyvinylidene fluoride) transducer in free field is also calibrated absolutely due to above results and its sensitivity is -118.5 dB.

Pressure and velocity cross-spectrum of normal modes in low-frequency acoustic vector field of shallow water and its application

The pressure and horizontal particle velocity combined descriptions in the very low frequency acoustic field of shallow wa- ter integrated with the concept of effective depth of Pekeris wave- guide is proposed, especially the active component of the pressure and horizontal particle velocity cross-spectrum, also called ho- rizontal complex cross acoustic intensity, when only two normal modes are trapped in the waveguide. Both the approximate theo- retic analysis and the numerical results show that the sign of the horizontal complex cross acoustic intensity active component is independent of the range when vertically deployed receiving dual sensors are placed in appropriate depths, the sum of which is equal to the waveguide effective depth, so it can be used to tell whether the sound source is near the surface or underwater; while the range rate is expected to be measured by utilizing the sign distribution characteristic of the reactive component. The further robustness analysis of the depth classification algorithm shows that the existence of shear waves in semi infinite basement and the change of acoustic velocity profiles have few effects on the application of this method, and the seabed attenuation will limit the detection range, but the algorithm still has a good robustness in the valid detection range.

Low intensity ultrasound stimulates biological activity of aerobic activated sludge

This work aims to explore a procedure to improve biological wastewater treatment efficiency using low inten-sity ultrasound.The aerobic activated sludge from a munici-pal wastewater treatment plant was used as the experimental material.Oxygen uptake rate(OUR)of the activated sludge(AS)was determined to indicate the changes of AS activity stimulated by ultrasound at 35 kHz for 0-40 min with ultrasonic intensities of 0-1.2 W/cm^(2).The highest OUR was observed at the ultrasonic intensity of 0.3 W/cm^(2) and an irradiation period of 10 min;more than 15%increase was achieved immediately after sonication.More significantly,the AS activity stimulated by ultrasound could last 24 h after sonication,and the AS activity achieved its peak value within 8 h after sonication,or nearly 100%higher than the initial level after sonication.Therefore,to improve the wastewater treatment efficiency of bioreactors,ultrasound with an intensity of 0.3 W/cm^(2) could be employed to irradiate a part of the AS in the bioreactor for 10 min every 8 h.

Effects of Low-Power Microwave Fields on Seed Germination and Growth Rate

Experiments were conducted to investigate the effects of low power microwave radiation on germination and growth rate in seeds. In the present paper, the bioeffects of low power (non-thermal intensity) microwave modulated with 1 KHz square wave have been studied. Experiments were performed in X-band frequencies using klystron based microwave test bench. Microwave parameters like frequency, power, exposure time and power density were varied while irradiating seed samples to study their influence on germination. The seed samples used for the experiment included wheat (Triticum aestivum), bengal gram (Cicer arietinum), green gram (Vigna radiate) and moth bean (Vigna Aconitifolia). Seed germination %, plant height, root length and dry matter % (biomass %) were recorded and compared with control seeds. The effects of different treatments were found to be stimulating the germination and seedling vigour of plants especially in power and exposure time treatments while increase in frequency and power density has reduced the seed germination and seedling vigour. The effect also varied with the nature of seeds.

半导体激光器抗辐照性能无损检测系统的研制

半导体激光器的电导数和低频电噪声参数可以反映器件的内部缺陷,与器件抗辐照性能具有相关性。介绍了基于电导数技术和低频电噪声技术设计的半导体激光器抗辐照性能检测系统,能够测量并提取激光器电导数及低频电噪声参数。通过微小剂量辐照前后的敏感参数对半导体激光器进行抗辐照性能评价,具有灵敏、无损等优势。

低强度超声波在污水生物脱氮中的研究进展

“双碳目标”背景下新型生物脱氮工艺更具有碳减排潜力。然而,以厌氧氨氧化工艺为代表的新型生物脱氮工艺在维持稳定运行状态方面受多种因素影响,导致脱氮效率不稳定,限制了其实际应用与推广。低强度超声波技术作为一种清洁高效的物理方法具有促进污泥活性、筛选微生物菌群的特点,与生物方法相结合可提高整体脱氮效果。论文围绕低强度超声波在强化生物脱氮性能中的作用展开讨论,介绍了超声波生物效应机理,分析了声能密度、辐照时间、超声频率等影响生物脱氮的因素,并从氮转化速率、污泥活性、微生物群落及污水生物脱氮的潜在机理方面综述了低强度超声波在污水生物脱氮中的应用,旨在为低强度超声波在脱氮实际应用中提供支撑。

超声优化水凝胶支架用于促进金纳米粒子的经皮递送

背景:金纳米粒子在多功能经皮给药系统的开发中具有重要意义,较小尺寸的金纳米粒子可通过细胞间路径向真皮层渗透,然而由于易团聚和胶体形态的限制,金纳米粒子存在着难以局限发挥效应、递送效率低的问题。目的:通过结合相变纳米液滴与生物黏附性水凝胶开发一种超声优化的水凝胶支架,用于金纳米粒子的经皮递送。方法:利用乳剂溶剂挥发法制备包载金纳米粒子的超声相变纳米液滴,并将其装载到聚多巴胺修饰的甲基丙烯酰化明胶水凝胶内制备复合水凝胶支架,对超声响应性纳米金载体进行结构与化学组分的表征,对复合水凝胶支架的微观结构、孔隙率、渗透性、流变学、体外止血及抗菌性能等进行表征。通过Live/Dead染色评价复合水凝胶支架的细胞相容性,并评估低强度脉冲超声对支架材料渗透性、孔隙率和力学性能的优化效果。结果与结论:①透射电镜和紫外-可见光光谱证明纳米金载体的成功构建,粒径及电位检测结果显示超声响应性纳米金载体具有较好的稳定性;②Live/Dead染色证明,复合水凝胶支架具有一定的生物相容性;③扫描电镜下可见复合水凝胶支架具有多孔网状结构,且部分大孔内部可见纳泡受超声辐照后产生的直径约2μm的微孔,结合渗透性实验说明强度脉冲超声可以优化水凝胶支架的孔隙和渗透性;复合水凝胶支架的止血性能优于止血海绵、聚多巴胺@甲基丙烯酰化明胶水凝胶支架;在低强度脉冲超声辐照下,复合水凝胶支架具有良好的抗氧化效应与抗菌性能;④热成像结果显示金纳米粒子包载在超声响应的纳泡中,在受到超声激励下可以得到更均匀的播散;⑤力学性能测试结果表明,负载含金纳米粒子的相变纳米液滴后水凝胶支架的储能模量增加,表现出更强的力学性能,断裂伸长率为122%,延展性优于不含金纳米粒子的相变纳米液滴组(P<0.05);⑥结果表明,复合水凝胶支架具备良好的生物相容性、抗菌性、抗氧化性及止血作用。

一种用于尿道瘢痕防治动物实验的超声探头设计

目的 尿道瘢痕是患者尿道手术后常见的并发症之一,并且难以通过手术治疗方法清除。低强度脉冲超声(low intensity pulse ultrasound,LIPUS)在抑制纤维化,抑制炎症方面有十分突出的表现,为超声防治尿道瘢痕提供了理论的可能性。尽管如此,目前并没有对超声用于尿道瘢痕的防治作用的报道,另外有关超声抑制纤维化、抑制炎症的作用机制也仍需要进一步的研究。本文针对新西兰雄兔尿道重建模型设计了一种超声探头,用于LIPUS抑制尿道瘢痕疗效和作用机制的动物实验研究。方法 根据兔阴茎的尺寸与形状设计探头结构,通过有限元仿真预测探头声场,用3D打印技术制造原型机。最后对探头声场进行测试,并且用于动物实验验证其实用性。结果 探头超声频率为2 MHz,治疗腔长度44 mm,直径8 mm。治疗腔沿长度方向上有3个紧邻的治疗区,每个治疗区的半功率长度约6 mm,治疗区内的I_(sata)(时间平均空间平均声强)可通过前端驱动器电源电压进行调节,当电源电压为30 V时,I_(sata)大于0.87 W/cm^(2)。结论 本文设计的超声探头体积小、重量轻、声场均匀,可以对动物尿道实施稳定有效的超声照射,为超声治疗尿道瘢痕动物实验提供了一种有用的工具。

低频低强度超声辐照微泡对三阴性乳腺癌MDA-MB 231/DOX细胞耐药性的影响

目的探讨低频低强度超声辐照微泡(LILFU-MB)对三阴性乳腺癌MDA-MB-231/DOX细胞耐药性的影响。方法筛选LILFU-MB最佳非毒性辐照时间,计算细胞存活率;将MDA-MB-231/DOX细胞分为LILFU-MB辐照组和非LILFU-MB辐照组,绘制药物抑制拟合曲线图获得两组药物的半抑制浓度(IC_(50)),并筛选阿霉素最佳剂量。根据不同处理方式将细胞分为对照组、阿霉素组、LILFU-MB组、LILFU-MB+阿霉素组,观察细胞增殖活性,并计算细胞迁移率。使用倒置荧光显微镜观察细胞形态,并记录细胞核荧光强度及细胞核型;使用流式细胞仪检测细胞凋亡率;Westernblot检测细胞蛋白表达情况。结果LILFU-MB最佳非毒性辐照时间为30 s,该条件下细胞存活率为(92.33±2.58)%,故后续实验中LILFU-MB辐照时间均采用此条件。LILFU-MB辐照组中阿霉素对耐药细胞的IC_(50)低于非LILFU-MB辐照组(7.51μmol/Lvs.35.40μmol/L),后续实验采用35.40μmol/L为阿霉素最佳剂量。阿霉素组和LILFU-MB+阿霉素组细胞增殖活性均受到明显抑制,增殖速度减慢,其中LILFU-MB+阿霉素组抑制效果最明显。对照组、阿霉素组、LILFU-MB组、LILFU-MB+阿霉素组细胞迁移率分别为(56.79±1.11)%、(51.34±4.66)%、(46.09±9.42)%、(22.01±6.02)%,其中LILFU-MB+阿霉素组细胞迁移率低于其余各组,差异均有统计学意义(均P<0.01)。倒置荧光显微镜观察显示,LILFU-MB+阿霉素组中大部分细胞核明显皱缩和碎裂,胞核蓝染高亮,染色质呈浓缩和边缘化,表现出较强的细胞凋亡核型改变。流式细胞仪检测结果显示,对照组、阿霉素组、LILFU-MB组、LILFU-MB+阿霉素组细胞凋亡率分别为(13.30±0.66)%、(22.68±2.85)%、(20.60±3.72)%、(31.84±2.87)%,其中LILFU-MB+阿霉素组细胞凋亡率高于其余各组,差异均有统计学意义(均P<0.05)。LILFU-MB+阿霉素组P-gp、Bcl-2蛋白表达均显著下调,Cyt-c、Cl-caspase3蛋白表达均显著上调,与其余各组比较差异均有统计学意义(均P<0.05)。结论LILFU-MB能够显著抑制MDA-MB-231/DOX细胞增殖、迁移,并促进细胞凋亡,进而逆转三阴性乳腺癌MDA-MB-231/DOX细胞耐药性。

Direct-chilling casting of Mg alloy under electromagnetic and ultrasonic combined field

The effects of low frequency electromagnetic (LFEC) field and ultrasonic (US) field on the microstructures, macrosegregation of alloying elements and the mechanical properties of DC cast AZ80 alloy were studied. The results show that both LFEC and US fields can refine the grains of the billets, which results in the increase in mechanical properties and uniformity of alloying element distribution. The effective refinement takes place on the edge of ingots when LFEC field is applied, while in the center of billets when field US is adopted. Combined the characteristics of LFEC and US fields, a new process for direct-chilling (DC) casting of Mg-electromagnetic-ultrasonic (ECUS) casting is developed, by which the grains are refined significantly and are more uniform in the whole ingots, and the mechanical properties of the ingots are improved.

超声纵扭-低频扭转复合振动攻丝实验

针对钛合金低频扭转振动攻丝效率偏低的问题,提出了超声纵扭-低频扭转复合振动攻丝方法。进行了超声纵扭振动攻丝实验、不同切削液的复合振功攻丝实验和变参数复合振动攻丝实验,研究复合振动攻丝的工艺效果及参数变化的影响规律。实验结果表明:超声纵扭振动增强了切削液的润滑效果,降低了攻丝扭矩,与普通连续攻丝相比,M3螺纹孔的超声纵扭振动攻丝可降低攻丝扭矩约18%;在所选参数范围内,与低频扭转振动攻丝相比,复合振动攻丝最大可降低攻丝扭矩约30%;复合振动攻丝降低攻丝扭矩的效果,随净切削量、主轴转速的增大和回退量的减小而降低。

镍基高温合金超声低频振动辅助钻孔试验

采用超声钻孔能够有效缓解轴向力作,提升孔屑排斥效果。为了提高镍基高温合金的钻孔质量,以Inconel718镍基高温合金为例开展超声低频振动辅助钻孔试验研究,完成系统超声低频振动测。钻孔试验结果表明:相比较普通钻孔,超声低频振动钻孔的轴向力与扭矩均值相对常规钻孔方式下降比例为10%~15%;超声低频振动钻孔原先螺旋切屑转变为许多断屑物,促进断屑并快速排出,获得稳定钻孔效果。该研究对提高Inconel 718镍基高温合金板的钻孔质量具有很好的实际应用价值。

双频点骨伤愈合超声波治疗仪的研究与设计

针对骨折、骨裂和骨挫伤等骨伤治疗中存在的恢复周期长、手术创伤和术后恢复期不便等问题,研制一款基于STM32单片机的骨伤愈合超声波治疗仪。该治疗仪以低强度脉冲超声波为治疗手段,通过刺激骨组织和神经系统的生物学反应,促进骨伤部位的修复和再生,并且具有非侵入性、无副作用等优点。通过实物测试证明,该治疗仪输出功率稳定,总体性能优良。目前该治疗仪已与某医院联合进行临床试验,为低强度脉冲超声波的应用开发提供一定参考。

缩泉汤加减联合低频超声导药治疗中老年膀胱过度活动症的临床研究

目的探讨缩泉汤加减、酒石酸托特罗定缓释片联合低频超声导药治疗脾肾气虚证膀胱过度活动症的临床疗效,并评估该方案的安全性。方法将96例患者随机分为3组,对照组1给予缩泉汤加减联合低频超声导药治疗,对照组2给予酒石酸托特罗定片治疗,治疗组患者同时接受上述两种药物治疗,疗程均为4周。通过观察OABSS评分、OAB⁃Qol评分和中医证候评分的变化,评价各组患者的疗效。结果研究过程中有12例患者脱落,最终纳入84例患者。对照组1、对照组2和治疗组的有效率分别为53.57%、60.71%和85.71%。治疗组在总体疗效上明显优于其他两组(P<0.05),两个对照组之间无显著差异(P>0.05)。中医症候评分、OABSS评分在治疗后均显著降低(P<0.05),且治疗组的评分较对照组更低(P<0.05)。在治疗过程中,未出现明显的不良事件或不良反应。结论缩泉汤加减联合低频超声导药治疗对于脾肾气虚证的中老年膀胱过度活动症具有显著的临床疗效,能显著改善患者症状,降低西药的使用频率,从而减少副作用的发生,提高患者的依从性及生活质量。

Investigation on the intensity noise characteristics of the semiconductor ring laser

Based on the frequency-domain multimode theoretical model, detailed investigations on the noise characteristic of the semiconductor ring laser （SRL） are first performed in this paper. The comprehensive nonlinear terms related to the third order nonlinear susceptibility Z3 are included in this model; the Langevin noise sources for electric field and carrier density fluctuations are also taken into account. As the injection current increases, the SRL may present several operation regimes. Remarkable and unusual low frequency noise enhancement in the form of a broad low frequency tail extending all the way to the relaxation oscillation peak is observed in any of the operation regimes of SRLs. The influences of the backscattering coefficient on the relative intensity noise （RIN） spectrum in typical operation regimes are investigated in detail.

钢筋混凝土桥面板弹性动力学特征研究

为解决半无限地域钢筋混凝土结构无损检测及空腔与钢筋波场相互干扰的问题,提出了梳状检波点全方向特征分析的低频超声波定量无损检测方法。首先引入了无限元人工边界,探索了边界尺寸对脉冲信号的衰减影响,然后提取了低频超声波在钢混结构中的全方向波场特征,通过特征反射时长确定空腔位置与尺寸。结果显示,所提方法可以有效减少边界反射波场带来的不利影响,降低噪点分贝,有利于时域信号的波场特征分析。对空腔钢筋的混凝土板进行空腔位置及尺寸的判定,误差分别为0.75%和2.0%,表明该方法不仅可以消除在结构材料与缺陷堆叠情况下的信号盲区,同时避免了特殊情况下斜入射震源的激发不便,实现了准确高效的缺陷检测。

红外线照射联合脉冲电刺激对髋部骨折患者术后恢复的影响

目的:探究红外线照射联合低频脉冲电刺激对髋部骨折患者术后康复的价值。方法:选取89名2021年7月至2023年5月上海市第二康复医院的髋部骨折患者,以随机数字法分为对照组(n=44,常规康复干预)和观察组(n=45,在对照组基础上以低频脉冲电刺激及红外线照射干预)。比较两组恢复情况、日常生活能力、髋关节功能、疼痛评分及腰背部功能。结果:观察组恢复情况优于对照组(P<0.05);干预6个月后,观察组日常生活能力、髋关节功能评分更高,疼痛、腰背部功能评分更低(P<0.05)。结论:红外线照射联合低频脉冲电刺激可促进髋部骨折患者术后恢复,提高其日常生活能力,减轻疼痛,改善其髋关节及腰背部功能。

低频超声测井仪主控系统设计与实现

针对低频超声测井仪声波发射、数据采集及数据传输于一体的控制要求,设计了一种基于DSP+FPGA异构控制技术的新型主控系统。该系统使用DSP作为主控制器,通过CAN总线与井下电缆遥传通信,根据接收的指令产生控制时序,使用有限状态机完成工作流程控制,创新性地采用基于加权马氏距离的健康度评估方法评判仪器工作状态。使用FPGA作为从控制器,采用指令数据通道独立控制方法实时转发控制指令,同步声波激发与采集,实时接收声波数据。采用基于自定义并口双口RAM的协同通信机制完成DSP与FPGA之间的数据传输。采用差分传输技术实现与发射系统、采集系统之间的通信。测试表明:该主控系统通信误码率低,控制实时性高,状态评估准确,具备声波发射、数据采集及数据传输一体化控制能力,满足低频超声测井仪控制要求。