Harmonic linearization of equations of forced oscillations of systems with dry-friction elements

A general method of the harmonic linearization of equations of forced oscillations of mechanical systems with dry-friction elements for arbitrary relationships between the intensity of the exciting forces and the limiting force of dry friction is explained. It is shown that the equation normally employed for harmonic linearization is valid only in the case when the limiting force of dry friction in the element is significantly lower than the reactive force that can be developed in the element in the absence of slip. A computational example for a system using a more precisely defined method of harmonic linearization is cited.Translated from Problemy Prochnosti, No. 6, pp. 89–92, June, 1990.     

Some questions of thermal strength in reactor construction

This paper considers some problems of the thermal strength of reactor materials, dealing with the nature of the stress and deformation states, creep, thermal fatigue, thermal shock, combination of thermal and mechanical stresses, and strength in temperature fields, varying in zones or with time. The possibility of micromechanical experiments to determine the mechanical properties of materials at various temperatures is also discussed.     

Maximal, three-wall, orbital decompression through a coronal approach

BACKGROUND AND OBJECTIVE: Only limited volume expansion is offered by traditional lateral orbital decompressions in which the anterior segment of the lateral wall is removed to allow lateral soft tissue prolapse. A great deal of additional soft tissue expansion can be obtained, not only laterally, but also posteriorly by removing the deep portion of the sphenoid wing. The authors report their experience in removing this bone through a coronal approach. PATIENTS AND METHODS: The authors performed maximal, three-wall, orbital decompressions through a coronal approach for 20 patients with thyroid-related orbitopathy. A disfiguring proptosis resulting from stable Graves' disease orbitopathy was the indication for surgery in all cases. Through a coronal approach, the lateral rim was left in place and thinned, augmented with specialized orbital rim onlay implants, or repositioned with osteosynthesis systems. The bone over the lacrimal fossa was sculpted to form a "keyhole" for the lacrimal gland, thereby providing additional orbital expansion. Once the medial canthal tendon and lacrimal sac had been elevated from their periosteal attachment, excellent exposure was obtained for medial and inferior orbital decompression. RESULTS: The authors report the results of 20 coronal orbital decompressions during a period of 44 months. Seven cases included lateral rim advancement. Up to 6 mm of retrodisplacement was achieved without rim augmentation, 9 mm with rim augmentation. DISCUSSION: The deep lateral orbital wall can provide significant room for volume expansion. The authors found that up to 6 mm of proptosis reduction can be obtained using the lateral wall alone. The coronal approach provides access to all four orbital walls for deep orbital decompression. The authors' philosophy of treatment in cases without compressive optic neuropathy is evolving toward the use of the lateral wall as the first approach with the incorporation of additional walls as needed.     

Nanomedicine-nanoemulsion formulation improves safety and efficacy of the anti-cancer drug paclitaxel according to preclinical assessment

Paclitaxel is an important anticancer drug and is currently used to treat a variety of cancers, including ovarian carcinomas, breast cancer, non-small cell lung cancer, and AIDS-related Kaposi's sarcoma. The objectives of the studies were to assess and compare the safety and efficacy of EmPAC (a newly developed nanoemulsion formulation of paclitaxel) versus Taxol (the injectable formulation of paclitaxel involving the use of polyethylated or polyoxyl castor oil currently used in the clinic). The objectives were also to investigate the mechanism for the improved safety and efficacy of EmPAC over Taxol. These results showed that EmPAC had better anti-tumor efficacy than Taxol, according to in vitro cell culture studies and studies in animal tumor models. EmPAC had improved anti-tumor efficacy even in tumor cell lines that are known to be multi-drug resistant. Part of the mechanism of action for the improved efficacy may be related to EmPAC inducing greater cellular uptake of paclitaxel into tumor cells than Taxol did, according to the in vitro cell culture radioactive-labeled studies and in vitro cell culture antibody studies. It may also partly be because EmPAC delivered more paclitaxel to the tumor mass than Taxol, while the delivery of paclitaxel to other tissues (e.g., blood, muscle, liver, spleen, kidney and lung) were similar between the two formulations of paclitaxel, according to studies in animals with tumor xenograft. EmPAC also had better safety than Taxol according to toxicology studies in rabbits. This may be because EmPAC does not contain the toxic ingredients used in formulating Taxol (such as polyethylated or polyoxyl castor oil). These results support the clinical development of the nanoemulsion formulation of paclitaxel.     

Memory for the Rey-Osterrieth Figure: Perceptual clustering, encoding, and storage.

Administered copy, immediate recall, and delayed recall conditions of the Rey-Osterrieth Complex Figure (ROCF) test to 50 neuropsychiatric patients (aged 23–83 yrs). Measures of copy accuracy, perceptual clustering, encoding, and savings were computed. Perceptual clustering in the copy condition was a better predictor of memory performance than was copy accuracy. An absence of association between the encoding score and the savings score suggests that these indices reflect different cognitive processes. The need to assess both immediate and delayed recall of the ROCF is emphasized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transitional vacuole formation following a bolus infusion of PEG-hemoglobin in the rat

This study was designed to assess the morphological effects of a bolus infusion of PEG-hemoglobin on the heart, lung, liver, spleen and kidney of laboratory rats. Of particular interest was the determination of PEG-hemoglobin's potential to form vacuoles in the tissues and whether these were transitory and article specific. One hundred ten female Sprague-Dawley rats were used in this study. The first experiment determined whether vacuole formation was test article specific by infusing either stroma-free bovine hemoglobin, PEG-hemoglobin, bovine serum albumin, PEG-bovine serum albumin or free PEG. The second experiment assessed the transitory nature of vacuolization. In both experiments, unconscious rats received an intravenous top-loading (bolus) injection of test article via the tail vein. Rats were sacrificed at various time points following administration and had their tissues examined for the presence of vacuoles by light microscope morphological examination and iron staining. Formation of vacuoles appeared to be test article specific with only prolonged circulating, high solute test articles producing vacuoles. These vacuoles appeared dose responsive and transitory in nature. The vacuolization found was non-toxic and believed to be due to the known effect of lysosomal overloading following the phagocytosis of vascularly persistent high solute test articles.     

Mathematical Modelling of Wave Propagation in a Rod of Time-Dependent Material

A numerical procedure to study one-dimensional waves in a rod, taking into account arbitrary rheological properties, is considered. The procedure is based on direct mathematical modelling of wave propagation in a rod of variable crosssection. Elastic-viscoplastic waves resulting from the impact of a rigid body, including repeated collisions and rebounds, are analyzed. This revised version was published online in July 2006 with corrections to the Cover Date.