Crystallinity variations in kaolinite induced by grinding and pressure treatments

Kaolinite samples treated with uniaxial pressures higher than 0.1 GPa or grinding times greater than 0.3 h show changes in their crystallinity. These changes are easily detected by the X-ray diffraction (XRD) technique and can be quantified from Hinckley (HI), Lietard (R₂) and also reference intensity ratio (RIR) index studies. The sensitivity of these indices to the Crystallinity changes is; HI>RIR>R₂. In the range of pressures and grinding times considered, these values can be diminished by 50%. The variations in these indices with either the pressure or grinding time follow logarithmic laws whose correlation coefficients are closed to unity. Infrared (IR) spectroscopy and thermal analysis studies show low sensitivity to the changes introduced by grinding or pressure. Nevertheless, thermal gravimetric curves confirm the decrease in the dehydroxylation starting point of about 100°C for the pressed and ground samples. Transmission electron microscopy (TEM) reveals important changes in kaolinite particle morphologies after pressure and grinding treatments. The samples compressed at 0.1, 0.32, 0.85, 1.0 and 2.0 GPa show a large number of defects (fractures, bending, deformations and rolling of layers, glide and rotation of the shell). The ground samples show grain boundaries, dislocations, twins and rounded voids. These defects are responsible for the decrease in crystallinity of the kaolinite samples shown in the XRD and IR studies.     

Fast acquisition clock and data recovery circuit with low jitter

This paper presents a half-rate clock and data recovery circuit (CDR)that combines the fast acquisition of a phase selection (PS) delay-locked loop (DLL) with the low jitter of a phase-locked loop (PLL). The PLL acquisition time improves considerably with use of a phase frequency magnitude detector(PFMD) that feeds back an estimate of the magnitude of the frequency difference in addition to the sign. Measurements in 0.5/spl mu/m CMOS technology show operation up to 700 Mb/s, a 7% acquisition range, an initial acquisition time of 8 bit times with jitter of 30% bit time, and jitter of 16 ps after the PLL acquires lock. With a phase frequency detector (PFD), the PLL locks in about 700 ns from an initial frequency difference of 7%. Measurements using a PFMD show the 700 ns PLL acquisition time is reduced on average by about a factor of 5 to 140 ns from an initial 7% frequency difference. The power dissipation is 300mW.     

How do the newer oral antimicrobials stack up against traditional agents?

As the antibiotic arsenal expands with the development of new oral agents, selecting appropriate therapy is becoming more difficult. What are the therapeutic indications for the newer antimicrobials, and what advantages do they have over traditional agents? Drs Gleckman and De La Rosa discuss current issues related to antibiotic treatment and offer specific recommendations for the best use of the newer agents.     

Conditions for stability of the extended Kalman filter and their application to the frequency tracking problem

The error dynamics of the extended Kalman filter (EKF), employed as an observer for a general nonlinear, stochastic discrete time system, are analyzed. Sufficient conditions for the boundedness of the errors of the EKF are determined. An expression for the bound on the errors is given in terms of the size of the nonlinearities of the system and the error covariance matrices used in the design of the EKF. The results are applied to the design of a stable EKF frequency tracker for a signal with time-varying frequency.This research was supported by the Co-operative Research Centre for Robust and Adaptive Systems ((CR)² ASys). The authors wish to acknowledge the funding of the activities of (CR)² ASys by the Australian Commonwealth Government under the Co-operative Research Centre Program.     

Unrelated bone marrow transplantation in a Wiskott-Aldrich syndrome patient sharing two HLA-extended haplotypes with the donor

OBJECTIVE: To determine the distribution and amount of elastic fibers in the dermis of clinically normal dogs and dogs with dermatoses, particularly solar dermatitis. DESIGN: Skin specimens from 7 anatomic sites were obtained from 19 clinically normal dogs after euthanasia to evaluate the normal distribution of elastic fibers. Biopsy specimens also were obtained from 34 dogs with dermatoses, including 16 with solar dermatitis. Tissue sections were stained with H&E, Verhoeff-van Gieson, and periodic acid-Schiff. ANIMALS: 19 clinically normal dogs and 34 dogs with dermatoses. PROCEDURE: Numbers of elastic fibers were graded subjectively. Comparisons between clinically normal dogs and dogs with dermatoses were made. RESULTS: Normal elastic fibers were present in low numbers in the dermis of adult dogs, regardless of anatomic site or presence or severity of dermatitis. Condensed elastotic material was visualized in only 2 dogs with solar dermatitis. In both dogs, the elastotic material was Verhoeff-van Gieson and periodic acid-Schiff stain positive but was not visible with H&E stain. The most frequent histopathologic finding in the dermis of dogs with solar dermatitis was superficial dermal fibrosis. CONCLUSIONS: The dermis of clinically normal dogs does not contain abundant elastic fibers. Alterations of elastic fibers in dogs with solar dermatitis are rare. Superficial dermal fibrosis may be a better indicator of solar damage.     

Noise and machine failures: determining factors in the acceptance and behavior of O2 concentrator. The Asturias project

Whether a sulfonylurea may be used together with insulin for treating NIDDM has been controversial. One view, based on older studies, has been that the additional benefit is too small or the level of glucose control achieved usually too poor to recommend this method. More recent studies of a more specific way of combining a sulfonylurea with insulin are more supportive. When a single injection of insulin taken in the evening is added to a sulfonylurea at the time of secondary failure of the sulfonylurea alone, glycemic control is quite simply and consistently restored to acceptable levels. At this time in the natural history of NIDDM, evening insulin combined therapy is more effective than a single injection of insulin alone, and just as effective as a more complex multiple-injection regimen without an oral agent. A recent multicenter trial of a new sulfonylurea, glimepiride, in combination with a single injection of 70/30 insulin before dinner has confirmed that this approach is safe and more consistently effective than insulin alone for obese patients beginning insulin in a setting resembling clinical practice. The available evidence suggests this form of combined therapy is suitable for routine use.     

单晶空心叶片用AC-2陶瓷型芯的组织和性能研究

利用扫描电镜技术和X射线衍射技术研究了AC－2氧化铝基陶瓷型芯的微观结构和相组成，并测试了该型芯的室温和高温性能，结果表明AC－2型氧化铝基陶瓷型芯的综合性能优于AC－1型芯。     

Clinical assessment research with older adults.

Methodological issues in geropsychological assessment research are discussed and exemplified with recent investigations. Increased use of short-term longitudinal designs, more diverse and representative sampling, and routine inclusion of measures of health are among the recommendations made for future studies. Caution is urged in the application of new tests or screening batteries until sufficient independent validation studies are completed. Research contrasting neuropsychological performance of older persons from different racial and ethnic groups is briefly reviewed, and applications of geropsychological assessment to practical arenas such as competency determination are critiqued. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A VSWR-protected silicon bipolar RF power amplifier with soft-slope power control

This paper presents the design and measured performance of a 1.8-GHz power amplifier featuring load mismatch protection and soft-slope power control. Load-mismatch-induced breakdown can be avoided by attenuating the RF power to the final stage during overvoltage conditions. This was accomplished by means of a feedback control system, which detects the peak voltage at the output collector node and clamps its value to a given threshold by varying the circuit gain. The issue of output power control has been addressed as well. To this end, a temperature-compensated bias network is proposed, which allows a moderate power control slope (dB/V) to be achieved by varying the circuit quiescent current according to an exponential law. The nonlinear power amplifier was fabricated using a low-cost silicon bipolar process with a 6.4-V breakdown voltage. It delivers a 33.5-dBm saturated output power with 46% maximum power-added efficiency and 36-dB gain at a nominal 3.5-V supply voltage. The device is able to tolerate a 10:1 load standing-wave ratio up to a 5.1-V supply voltage. Power control slope is lower than 80 dB/V between -15 dBm and the saturated output power level.     

异步电机性能微机测试系统设计

结合工程实际介绍了异步电机计算机辅助测试（CAT）系统的硬件、软件组成、技术方案确定以及设计原则。现场运行表明，该系统稳定可靠，且具有较高的性能价格比。