The accuracy of brackets placement in direct bonding technique: a comparison between the pole-like bracket positioning gauge and the star-like bracket positioning gauge

The accuracy of brackets placement is a key factor in successful orthodontic therapy. An in vitro study was conducted in ten models from a natural maxillary teeth model in order to compare the accuracy of brac- kets placement between two direct bonding instru- ments: the Pole-like Bracket Positioning Gauge and the Star-like Bracket Positioning Gauge. Our results have shown that: The Star-like Bracket Positioning Gauge is more precise in placing brackets vertically, whereas the Pole-like Bracket Positioning Gauge al-lows a better angulation of the bracket. Considering each tooth separately, there is no statistically signifi-cant difference between the two positioning gauges, except that the Star-like gauge gives better results in bracket’s height for the second premolar and the ca-nine, whereas the Pole-like gauge allows for a better positioning and a better vertical angulation of the brackets for the lateral incisor. No statistically signi- ficant difference was found between the two gauges on the mesiodistal position. Overall, the Star-like gau- ge showed a better accuracy in positioning brackets.

EFFECT OF HYDROGEN BONDING ON DIRECTION OF PHOTOISOMERIZATION OF RETINOIDS:THE ORIGIN OF THE SOLVENT POLARITY EFFECT.

Studies of direction of photoisomerization of retinal,retinonitrile,a- retinonitrile and a trienenitrile analog in different solvents with varying wave- lengths of excitation and reaction temperature led to the conclusion that the well known solvent dependent photochemistry of retinoids is due to selective excitation of the hydrogen bonded species.

RECENT DEVELOPMENTS OF DIRECT BONDED COPPER(DBC)SUBSTRATES FOR POWER MODULES

DBC substrates are the standard circuit boardsfor power modules. Using the DBC technologythick copper foils (0.125mm - 0.Tmm) arecladded to Alumina or Aluminum Nitride,The strong adhesion of the copper to ceramicbond reduces the thermal expansion coefficientin horizontal direction only slightly above theTEC of the ceramic itself. This allows directsilicon attach of large dies without using TECcontrolling layers.As DBC technology is using copper foils,integralleads overhanging the ceramic can be realized...

Wire Bonding Using Offline Programming Method

Manual process of creating bonding diagram is known to be time consuming and error prone. In comparison, offline programming (OLP) provides a much more viable option to reduce the wire bonding creation time and error. OLP is available in two versions, i.e., vendor specific OLP and direct integration offline pro- gramming (Di-OLP). Both versions utilize the bonding diagram and computer aided design data to speed up bonding program creation. However, the newly proposed Di-OLP is more flexible as it can be used to create bonding program for multiple machine platforms in microelectronics industry. Some special features of Di-OLP method are presented. The application of generic OLP however, is applicable to machines that recognize ASCII text file. The user needs to know the data format accepted by machine and convert the data accordingly to suit its application for different machine platforms. Di-OLP is also a practical method to replace the time consuming manual method in production line.

可乐丽菲露SE BOND用于直接盖髓术的组织学评价

目的:对可乐丽菲露SEBOND在人体用于直接盖髓术进行组织学评价。方法:选择24名志愿者共45颗健康人第三磨牙,41颗在牙合面制备Ⅰ类洞并在洞底作人工穿髓孔,然后分为2组,实验组以可乐丽菲露SEBOND盖髓,对照组以氢氧化钙盖髓。4颗作为空白对照。所有实验牙齿分别在盖髓后的7、30、90d后拔除并进行组织学检测。结果:实验组和对照组志愿者均未出现术后实验牙齿敏感症状。病理检测显示,在7d和30d的观察期内2组均有轻度到中度的炎性反应,但可乐丽菲露SEBOND组的炎性反应较氢氧化钙组轻,其组织学评价分级上的差别有统计学意义(P<0.05)。在90d的观察期内2组均无明显的炎性反应,而牙本质桥的形成在氢氧化钙组显著多于可乐丽菲露SEBOND组,氢氧化钙组7例标本中有6例标本有牙本质桥的形成,可乐丽菲露SEBOND组7例标本中有3例形成,其差别有统计学意义(P<0.05)。结论:可乐丽菲露SEBOND对牙髓的刺激性较小,但诱导牙本质形成的能力较氢氧化钙弱。

可乐丽菲露SE BOND应用于Beagles犬直接盖髓术的组织学评价

目的将可乐丽菲露SE BOND用于beagles犬直接盖髓术后,进行组织学分级评价。方法选择6只bea-gles犬共130颗健康牙齿,在颊面制备Ⅴ类洞并在洞底作人工穿髓孔,然后分为2组,实验组以可乐丽菲露SE BOND盖髓,对照组以氢氧化钙盖髓。所有实验牙齿分别在盖髓后的第7、30、90天拔除,并进行组织学评价。结果病理学评价显示,在7 d的观察期内2组的牙髓均呈轻度到中度的炎性反应,可乐丽菲露SE BOND组的炎性反应较氢氧化钙组轻,但其差别没有统计学意义。在30 d和90 d的观察期内2组均无明显的炎性反应,而牙本质桥的形成在氢氧化钙组显著多于可乐丽菲露SE BOND组,其差别有统计学意义(P<0.05)。结论可乐丽菲露SE BOND对牙髓的刺激性较小,但诱导牙本质形成的能力较氢氧化钙弱。

Si-Si直接键合的研究及其应用

硅片直接键合技术是一种简单易行的硅片熔合技术,由于该技术不受材料的结构、晶向和点阵参数的影响,因而得到了广泛的应用。介绍了硅片直接键合的方法和键合模型,并简单介绍了硅片直接键合技术的应用。

Si-Si直接键合的杂质分布

在Si-Si直接键合过程中,界面处存在一层很薄的厚度恒定的本征SiO2.Si对SiO2中的杂质的抽取效应,导致了杂质在界面处的浓度大大降低,根据改进了的杂质在Si-Si直接键合片中分布模型,推导出了杂质分布的表达式,在理论上和实验上都对该式进行了验证.杂质通过SiO2再向Si中扩散的杂质总量与Si-Si扩散相比大大减少,使所形成的p-n+结的结深减小.

Study on Shear Strength Characteristics of Basalt-Concrete Bonding Interface Based on in-situ Direct Shear Test

In rock engineering,the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations,embedded rock piles and rock bolts.In this study,30 sets of in-situ direct shear tests were conducted on the basalt-concrete bond interface in the Baihetan dam area to investigate the shear strength characteristics of the basalt-concrete bonding interface.The bonding interface contains two states,i.e.,the bonding interface is not sheared,termed as se(symbolic meaning see Table 1);the bonding interface is sheared with rupture surface,termed as si.The effects of lithology,Joints structure,rock type grade and concrete compressive strength on the shear strength of the concrete-basalt contact surface were investigated.The test results show that the shear strength of the bonding interface(s_(e)&s_(i))of columnar jointed basalt with concrete is greater than that of the bonding interface(s_(e)&s_(i))of non-columnar jointed one with the same rock type grade.When the rock type grade isⅢ_(2),fcol is 1.22 times higher than fncol and ccol is 1.13 times greater than cncol.The shear strength parameters of the basalt-concrete bonding interface differ significantly for different lithologies.The cohesion of the bonding interface(s_(i))of cryptocrystalline basalt with concrete is 2.05 times higher than that of the bonding interface(s_(i))of breccia lava with concrete under the same rock type grade condition.Rock type grade has a large influence on the shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i)).cnol increases by 33%when the grade of rock type rises fromⅢ_(1)toⅡ_(1).the rock type grade has a greater effect on bonding interface(s_(i))cohesion than the coefficient of friction.When the rock type grade is reduced fromⅢ_(2)toⅢ_(1),f_(ncol)′increases by 2%and c_(ncol)′improves by 44%.The shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i))increases with the increase of the compressive strength of concrete.When concrete compressive strength rises from 22.2 to 27.6 MPa,the cohesion increases by 94%.

Reshapeable,rehealable and recyclable sensor fabricated by direct ink writing of conductive composites based on covalent adaptable network polymers

Covalent adaptable network(CAN)polymers doped with conductive nanoparticles are an ideal candidate to create reshapeable,rehealable,and fully recyclable electronics.On the other hand,3D printing as a deterministic manufacturing method has a significant potential to fabricate electronics with low cost and high design freedom.In this paper,we incorporate a conductive composite consisting of polyimine CAN and multi-wall carbon nanotubes into direct-ink-writing 3D printing to create polymeric sensors with outstanding reshaping,repairing,and recycling capabilities.The developed printable ink exhibits good printability,conductivity,and recyclability.The conductivity of printed polyimine composites is investigated at different temperatures and deformation strain levels.Their shape-reforming and Joule heating-induced interfacial welding effects are demonstrated and characterized.Finally,a temperature sensor is 3D printed with defined patterns of conductive pathways,which can be easily mounted onto 3D surfaces,repaired after damage,and recycled using solvents.The sensing capability of printed sensors is maintained after the repairing and recycling.Overall,the 3D printed reshapeable,rehealable,and recyclable sensors possess complex geometry and extend service life,which assist in the development of polymer-based electronics toward broad and sustainable applications.

Coulomb exploded directional double ionization of N2O molecules in multicycle femtosecond laser pulses

We experimentally investigate Coulomb exploded directional double ionization of N2O molecules in elliptically polarized femtosecond laser pulses.The denitrogenation and deoxygenation channels are accessed via various pathways.It leads to distinct asymmetries in directional breaking of the doubly ionized N2O molecules versus the instantaneous laser field vector, which is revealed by tracing the sum-momentum spectra of the ionic fragments as a recoil of the ejected electrons.Our results demonstrate that the accessibility of the Coulomb exploded double ionization channels of N2O molecules are ruled by the detailed potential energy curves, and the directional emission of the fragments are governed by the joint effects of the electron localization-assisted enhanced ionization of the stretched molecules and the profiles of the molecular orbitals.

硅/硅低温直接键合的工艺调控及应用

为了满足微机电系统(MEMS)对高强度、低成本、灵活性好、通用性强硅/硅低温直接键合技术的迫切需求,开展基于氧等离子活化的硅/硅低温直接键合工艺调控方法及应用研究。通过正交实验分析了活化功率、活化时间、氧气流量对键合率和键合强度的影响,优化了氧等离子活化工艺,350℃氮气保护下退火2 h后,键合率为98.52%,平均抗剪切强度为20.2 MPa,键合界面连续无空洞,且形成了3.58 nm的非晶氧化层,表明实现了分子间的键合。最后,采用三层低温硅/硅键合工艺实现了微型振动能量收集器的限幅封装,成功将能量收集器的频带拓展到215 Hz~229 Hz。结果表明,该硅/硅键合工艺满足MEMS器件的加工及使用要求,其工艺调控方法具有较好的通用性。

复合树脂直接粘接技术用于前牙美学修复的疗效分析

目的探讨复合树脂直接粘接技术在前牙美学修复中的应用效果。方法以2022年6月至2024年1月在安徽医科大学附属巢湖医院行前牙美学修复的54例患者为研究对象,所有患者均采用复合树脂直接粘接技术进行修复。统计前牙美学修复成功率,并分析失败原因。结果随访结果显示54例患者中有50例修复成功,修复成功率为92.59%。4例修复失败,失败率为7.41%,其中树脂脱落2例,树脂变色1例,边缘不密合1例。结论复合树脂直接粘接技术用于前牙美学修复中可取得较好的临床疗效,可有效恢复前牙结构、功能和美观程度。

硅基钽酸锂异质晶圆键合工艺研究

5G移动通信的发展对声表面波滤波器提出了高频、小型化、集成化的要求。相较于传统压电体单晶材料,采用硅基压电单晶薄膜材料制备的声表面波滤波器具有高频、低插入损耗、高温稳定性等优势,是高性能声表面波器件发展的核心基础材料。Smart-Cut^(TM)是制备硅基压电单晶薄膜材料的主要方法,键合工艺是其中的核心工序,键合质量决定了硅基压电单晶薄膜晶圆材料的质量,并影响器件性能。本文通过低温直接键合工艺,对等离子活化、兆声清洗、预键合、键合加固四道工序展开优化,最终实现了键合强度高达1.84 J/m^(2)、键合面积超过99.9%的高质量硅基钽酸锂异质晶圆键合。

2-(甲氧基亚胺基)苯乙酸的合成研究

研究了2-(甲氧基亚胺基)苯乙酸即苯基MIA的合成,并对该工艺的反应条件进行了筛选和优化。将甲氧基胺基盐酸盐和碳酸钠固体分别加入圆底烧瓶中,溶于干燥的二氯甲烷,0℃下加入苯甲酰甲酸,25℃下反应3h。该工艺方法得到72%左右的收率,且反应条件简单温和,工艺设备成本廉价,实现了操作简单、经济实惠和绿色环保的目的。

复合树脂多层修复技术与复合树脂直接粘接修复技术在前牙间隙美学修复中的效果对比

目的:对比分析复合树脂多层修复技术与复合树脂直接粘接修复技术在前牙间隙美学修复中的效果。方法:纳入笔者医院2020年6月-2021年6月收治的98例(共104颗患牙)前牙间隙患者作为研究对象,按照随机数表法分为A组和B组,各49例。A组患者接受复合树脂多层修复技术,B组患者接受复合树脂直接粘接修复技术。对比两组修复效果、美学效果和治疗总费用,比较两组修复前和修复30d后、6个月后的咬合力、咀嚼效率和焦虑自评量表(Self-ratinganxietyscale,SAS)、抑郁自评量表(Self-rating depression scale,SDS)评分。结果:修复30 d后,A组优秀率高于B组(P<0.05),两组良好率和不良率比较无统计学意义(P>0.05)。修复6个月后,A组优秀率和不良率均高于B组(P<0.05),两组良好率比较无统计学意义(P>0.05)。患者的咬合力在时间、交互作用上差异有统计学意义(P<0.05),在组间作用上差异无统计学意义(P>0.05)。患者的咀嚼效率在时间、组间、交互作用上差异均有统计学意义(P<0.05)。修复6个月后,两组患者咬合力和咀嚼效率均较修复30d后和修复前升高,且A组咬合力和咀嚼效率高于B组(P<0.05)。A组修复后的边缘密合性、颜色匹配性、修复体崩裂、继发龋损、形态匹配、修复体脱落和牙龈健康评分均低于B组(P<0.05)。患者的SAS评分和SDS评分在时间、组间、交互作用上有统计学意义(均P<0.05)。修复30d后和修复6个月后,两组患者SAS和SDS评分均较修复前降低,且A组低于B组(P<0.05)。A组治疗总花费高于B组(P<0.05)。结论:与复合树脂直接粘接修复技术相比,在前牙间隙美学修复中应用复合树脂多层修复技术可取得更佳的修复效果,有助于恢复患者咬合力和咀嚼功能,使患者获得良好美学效果,改善其心理状态。但治疗总花费相对较高,临床治疗需结合患者经济情况选择合适治疗方案。

车用碳化硅功率模块的电热性能优化与评估

由于在开关速度、温度特性和耐压能力等方面的优势,SiC(silicon carbide)功率模块开始逐步应用于电动汽车的电机控制器。电机控制器是电动汽车的核心部件,对功率模块的电热特性要求较高,因此对SiC封装提出了很大的挑战。以主流的HybridPACK Drive模块封装为例,优化设计了模块的驱动回路和DBC(direct bonded copper)布局,并引入了铜线键合技术,协同优化了模块的电热性能和可靠性。此外,采用响应面法优化了椭圆形Pin-Fin散热基板,提升了模块的散热性能。最后,分别制造了优化前、后的SiC功率模块样机作为对比,搭建了双脉冲和功率对拖实验平台,评估了2种方案的电热性能。实验结果显示,当芯片交错距离为芯片宽度的1/2时,所优化的功率模块可以在兼顾电性能的同时,实现更优异的热性能。

溶剂导向合成两个氢键型金属有机框架

利用溶剂作为结构导向剂,以相同的反应物在不同溶剂中合成两个氢键型金属有机框架(MOFs),分子式分别为Cd(obb)(en)[NH(CH_(3))_(2)]·DMF(1)和Cd(obb)_(2)(en)_(2)·DMA(2)(H_(2)obb=4,4′-二苯醚二甲酸,en=乙二胺,DMF=N,N′-二甲基甲酰胺,DMA=N,N′-二甲基乙酰胺)。单晶X射线结构分析显示,化合物1和化合物2具有一个共同的结构特征:金属原子和obb^(2-)配体形成一维链,该一维链通过氢键连接形成二维层。然而,这两个MOFs之间存在明显的差异。化合物1中包含结构有序的DMF客体分子,并通过强的主-客体氢键相互作用将其固定在层间。化合物2中,二维层通过层间相互作用相互连接形成三维框架,由于缺少强相互作用,无序的DMA客体分子填在其中,无法通过单晶数据确定。这两种化合物表现出优异的溶剂稳定性。值得注意的是,化合物2具有永久的孔隙性和吸附气体的能力,在一个大气压下,化合物2对氮气的最大吸附量约为38 mL/g,使其成为潜在的气体储存/分离候选材料。

Chiplet晶圆混合键合技术研究现状与发展趋势

半导体产业对国防安全和国民经济发展意义重大,高端半导体装备也是国外对华技术封锁的重点领域。混合键合技术作为微电子封装和先进制造领域的一种新型连接技术,已经成为实现芯片堆叠、未来3D封装的一项关键技术,是实现高性能、高密度和低功耗芯片设计的关键技术之一。分析了Chiplet晶圆混合键合技术应用背景,梳理了典型工艺及设备研究的现状,并展望了晶圆混合键合技术发展趋势。

计及磁链和电流的PMSM DTC系统中功率器件键合线老化监测方法

在闭环控制系统中,基于电参数的功率器件老化监测方法是电力电子可靠性领域的难点之一。以永磁同步电机直接转矩控制系统为例,研究基于磁链相图和电流的功率逆变器中功率器件老化状态的在线监测方法。首先,分析功率器件老化的特征,得到键合线老化引起通态电阻增加的结论;其次,研究得到功率器件键合线老化与磁链相图、直轴电流和三相电流峰值变化的关系,进而提出功率器件键合线老化的监测方法;最后,通过多组仿真实验验证了基于磁链相图和电流的在线监测方法均可实现功率逆变器中功率器件键合线老化状态的在线监测。其中,基于磁链相图的在线监测方法需要系统磁链出现一些波动时才易观测,此时功率器件处于失效状态,该方法并不可取;而基于三相电流的监测方法能够更为精确地监测功率器件老化状况,效果更为优越。