Identification of joint parameters using FRF based decoupling

Structural and mechanical systems are assembled from smaller components using mechanical joints. The mechanical properties of the joints must be modeled in order to perform subsequent design and analysis of the structure or mechanical system. This study provides an analytical method of determining the parameters that describe the behavior of the joints using frequency response function (FRF) data that is measured at joint nodes. The variation in FRFs is derived by utilizing the consistent response conditions at the same joint nodes of the assembly system and the portioned subsystems. The variation reflects the mechanical properties of the joint and is utilized to extract the joint parameters. The validity of the proposed method is illustrated in two numerical applications

Influence of Calcium Sulfate Type on Evolution of Reaction Products and Strength in NaOH- and CaO-Activated Ground Granulated Blast-Furnace Slag

This study investigated the influences of CaSO4 type (i.e., anhydrite vs. gypsum) on strength development and reaction products in the activation of ground granulated blast-furnace slag (GGBFS) when different activators (i.e., CaO vs. NaOH) and sources of GGBFS were used. In the CaO-activation, the addition of calcium sulfates greatly enhanced 28-day strengths, regardless of the choice of CaSO4 or GGBFS source, through increasing the quantities of reaction products and reducing pore volume and size. However, in the NaOH-activation, the use of calcium sulfates showed the complex dependency of strength on the choice of CaSO4 type and GGBFS source, and it barely produced beneficial effects on the quantity of reaction products and reduction of pore volume and size. Thus, the results in this study indicate that the combination of CaO-activation and calcium sulfates is a more effective means of activating GGBFS to gain enhanced strength and significant quality control than the use of gypsum with NaOH-activation

Ethanol Extract of the Flower Chrysanthemum morifolium Augments Pentobarbital-Induced Sleep Behaviors: Involvement of Cl− Channel Activation

Dried Chrysanthemum morifolium flowers have traditionally been used in Korea for the treatment of insomnia. This study was performed to investigate whether the ethanol extract of Chrysanthemum morifolium flowers (EFC) enhances pentobarbital-induced sleep behaviors. EFC prolonged sleep time induced by pentobarbital similar to muscimol, a GABAA receptors agonist. EFC also increased sleep rate and sleep time when administrated with pentobarbital at a subhypnotic dosage. Both EFC and pentobarbital increased chloride (Cl−) influx in primary cultured cerebellar granule cells. EFC increased glutamic acid decarboxylase (GAD) expression levels, but had no effect on the expression of α1-, β2-, and γ2-subunits of the GABAA receptor in the hippocampus of a mouse brain. This is in contrast to treatment with pentobarbital, which showed decreased α1-subunit expression and no change in GAD expression. In conclusion, EFC augments pentobarbital-induced sleep behaviors; these effects may result from Cl− channel activation

Effect of Silica Fume on the Volume Expansion of Metakaolin-Based Geopolymer Considering the Silicon-to-Aluminum Molar Ratio

This paper investigates the effect of silica fume on the mechanical properties of metakaolin-based geopolymers with different silicon-to-aluminum molar (S/A) ratios. Geopolymer has been extensively studied as an alternative to traditional cementitious material because of its low CO2 emissions. Previous studies revealed that the application of silica fume can improve the compressive strength of geopolymer, however, the optimum dosages are different. To examine the reason for the different optimum dosages of silica fume, this study prepares geopolymer specimens of which variables are the S/A ratio and silica fume dosage, and conducts compressive strength and initial setting time tests. To examine whether the strength degradation is caused by the expansion due to the added silica fume in geopolymer, the volume and dynamic modulus are also measured. The results show that a part of silica fume dissolves and changes the S/A ratio of geopolymer, and that a part of silica fume remains in the geopolymer matrix. These combined effects of silica fume result in an irregular compressive strength trend, and, thus, an optimum dosage of silica fume can vary depending on the S/A ratio. Furthermore, the volume expansion of geopolymer with silica fume is observed, however, no sign of damage on the compressive strength is found

Mesenchymal Stem Cell-Extracellular Vesicle Therapy for Stroke: Scalable Production and Imaging Biomarker Studies

A major clinical hurdle to translate MSC-derived extracellular vesicles (EVs) is the lack of a method to scale-up the production of EVs with customized therapeutic properties. In this study, we tested whether EV production by a scalable 3D-bioprocessing method is feasible and improves neuroplasticity in animal models of stroke using MRI study. MSCs were cultured in a 3D-spheroid using a micro-patterned well. The EVs were isolated with filter and tangential flow filtration and characterized using electron microscopy, nanoparticle tracking analysis, and small RNA sequencing. Compared to conventional 2D culture, the production-reproduction of EVs (the number/size of particles and EV purity) obtained from 3D platform were more consistent among different lots from the same donor and among different donors. Several microRNAs with molecular functions associated with neurogenesis were upregulated in EVs obtained from 3D platform. EVs induced both neurogenesis and neuritogenesis via microRNAs (especially, miR-27a-3p and miR-132-3p)-mediated actions. EV therapy improved functional recovery on behavioral tests and reduced infarct volume on MRI in stroke models. The dose of MSC-EVs of 1/30 cell dose had similar therapeutic effects. In addition, the EV group had better anatomical and functional connectivity on diffusion tensor imaging and resting-state functional MRI in a mouse stroke model. This study shows that clinical-scale MSC-EV therapeutics are feasible, cost-effective, and improve functional recovery following experimental stroke, with a likely contribution from enhanced neurogenesis and neuroplasticity

Bilateral tension pneumothorax caused by an abrupt increase in airway pressure during cervical spine surgery in the prone position -A case report-

Elevated peak inspiratory airway pressure (PIP) can occur during general anesthesia and is usually easily rectified. In rare circumstances it can lead to potentially fatal conditions such as tension pneumothorax. We report on a 77-year-old male patient admitted for a cervical laminoplasty. The preoperative chest radiograph showed normal findings and there was no medical history of allergy or underlying airway inflammation. Anesthesia induction and maintenance progressed uneventfully. However, 5 minutes after prophylactic antibiotic administration, PIP suddenly increased and blood pressure dropped. The operation was abandoned and the patient was moved to a supine position to perform chest radiography. Cardiac arrest occurred, and cardiopulmonary resuscitation was performed. The radiograph showed bilateral tension pneumothorax. Needle aspiration was immediately performed, and chest tubes were inserted. Ventilation rapidly improved and the vital signs normalized. The patient was discharged without sequelae on postoperative day 36

Transfer Path Analysis of Output Noise Using Multi- dimensional Spectral Analysis Method For Vacuum Cleaner

ABSTRACT Noise reduction of vacuum cleaner is important, according as estimating quality of product. To reduce noise of vacuum cleaner, we need analysis of correct noise source and contribution grasping about Identified noise sources' output noise. Because noise sources' correlation exists in vacuum cleaner that is small and complicated system, and analysis is not easy. In this case, we need to apply Multi-dimensional spectral analysis (MDSA) method that can remove correlation among noise sources and grasp pure contribution degree of noise sources. In this study, we analyze transfer path analysis between output noise and input noise that measured in inside/outside of vacuum cleaner