Advanced adhesive restorations: the post-amalgam age

Due to patient demand for biocompatible, safe, and tooth-colored restorations, the use of amalgam as a restorative material has been declining. Currently, the profession of operative dentistry is in a state of transition from the amalgam age to the post-amalgam age. The learning objective of this article is to discuss the current state of the art of tooth-colored restoratives--amalgam substitutes and amalgam alternatives--used either as direct or laboratory fabricated restorations nationally and internationally. Adhesive dentistry is discussed in detail, with tooth preparation as the key element. The challenges facing the clinician during the transition period include clinician education, restorative concepts and teaching competence, costs, prevention, and maintenance.     

Dysphagia due to cervical spine involvement in ankylosing spondylitis

Here we present a case of a patient with a massive ossification of annulus fibrosus and longitudinal ligament at the level C3-C4, C4-C5 and C5-C6, also called the Van Swaay bridge. One can observe a propulsion of the pharingeal tissue at the level of the massive Van Swaay bridge between C5 and C6 which caused pressure and dysphagia.     

半导体激光器列阵有源区电场随电流变化的定点测量

采用连续波电光检测法，对ＧａＡｓ／ＧａＡｌＡｓ双异质结激光器列阵有源区进行定点测量，实验结果反映了发光区内及发光区外电场随电流变化的不同规律。文中对实验结果给出了合理解释。     

Measurements of distribution of self-bias potential on an RF-plane electrode in plasma etching devices

The self-bias potential (V_dc) induced on an RF-powdered electrode (153 mm Ø) in a plasma is measured using electrical probes which are buried in, de-insulated from, and RF-connected to the electrode. The configuration of the probes allows to study the distribution of V_dc discretely on the electrode. The potential is homogeneous in the absence of external magnetic field. In the presence of a homogeneous magnetic field parallel to the electrode, it is reduced and a monotonous gradient takes place in its distribution due to the plasma shift induced by E × B drift. When the magnetic field is rotated along the axis of the RF-electrode at a frequency less than 50 Hz, the distribution, which is almost identical to the one in a static field, rotates with the magnetic field. On the coordinate system rotating with the magnetic field, the probes are regarded to be rotating. The potential distribution is obtained as a continuous function of the azimuthal angle. Thus the rotation of the field provides information for the experimental interpolation.     

令牌多环网性能—可靠性综合评价

网络的性能与可靠性已分别得到广泛的研究,然而,怎样分析具有容错机制的环网的性能仍属有待开拓的研究领域,本文提出了一种分析具有自修复机制的多环网络系统的方法,并给出了报文传输时间分布的拉氏变换式,平均等待时间及平均队列长度公式,分析结果可用于评估故障与修复过程对实时令牌环网的实时响应特性的影响,对基于LAN的分布式实时系统设计具有指导意义。     

RADIATION FIELD FROM A RECTANGULAR PLAQUE SOURCE FOR RADIATION PROCESSING

Evaluation of the Hubbell integral for an omnidirectional detector response to a rectangular plaque gamma emitting radiation source using a different numerical computation method on a personal computer was made. For a plaque consisting of several strip gamma emitters, exposure rates at different positions above the source were calculated using 'exact' evaluation and an approximate method. Optimization method is used to find source activity of each strip, so as to acquire desirable dose uniformity of the irradiated products. In uses of the Hubbell integral, by introducing appropriate programming, computation time can be saved.     

Measurement of the compressive creep strain rates of the individual phases within a lamellar microstructure

A fuducial line technique has been developed to determine the creep properties of the constituent phases within a lamellar composite subject to compression creep deformation. The technique can yield information on the total strain, creep rate, and the stress exponent and activation energy for creep of the individual phases within a lamellar microstructure. The contribution of interphase interfacial sliding to the strain of lamellar composites can also be evaluated by using the fiducial line technique. Application of the fiducial line analysis to a two-phase TiAl/Ti₃Al lamellar alloy deformed in compression at 1080K and 380MPa yields good agreement between the creep strain determined using the fiducial line analysis and the value directly measured from the crept specimen. The fiducial line analysis reveals that the TiAl phase within the two-phase TiAl/Ti₃Al lamellar microstructure creeps 2.2 times faster than the Ti₃Al phase and that interfacial sliding does not contribute to creep deformation of this alloy, within the resolution limit of the fiducial line experiment.     

江苏省本地电话网结构与发展

分片汇接的网状网结构是江苏省本地电话网的基本框架,而汇接局和连接汇接局的传输系统则是网路规划与通信建设的重点。     

Distraction effects on muscle. Leg lengthening studied in rabbits

We investigated changes in the anterior tibial muscle during lengthening of the lower leg in rabbits. In 37 rabbits, an osteotomy of the right middle tibia was performed and was fixed by a unilateral external fixator. The rabbits were randomized into 6 groups. In groups 1, 2, and 3 the tibiae were distracted 0.5 mm/day. In groups 1 and 2, the rabbits were killed after 14 and 28 days of distraction, respectively, and in group 3 after 28 days of distraction, followed by 14 days of rest. Groups 1a, 2a, and 3a served as controls. They were treated similarly as groups 1, 2, and 3, but no distraction was performed. Proliferating cell nuclei were labeled with 5-bromo-2-deoxyuridine and were identified by immunohistochemical staining. The weight of the muscle was measured. During bone lengthening the muscle showed signs of growth, as indicated by increasing weight and number of proliferating cell nuclei. This was observed only during lengthening and it ceased when the lengthening was stopped.