The wave and finite element (WFE) method is a numerical approach to the calculation of the wave properties of structures of arbitrary complexity. The method starts from a finite element (FE) model of ...only a short segment of the structure, typically by using existing element libraries and commercial FE packages. The dynamic stiffness matrix of the segment is obtained, a periodicity condition applied and an eigenvalue problem formed whose solution gives the dispersion equations and wave mode shapes. These define a wave basis from which the forced response can be found straightforwardly. Although straightforward in application, the WFE method is prone to numerical difficulties. These are discussed in this paper and methods to avoid or remove them described. Attention is focused on 1-dimensional waveguide structures, for which numerical problems are most severe. Three ways of phrasing the eigenvalue problem for free wave propagation are presented and a method based on singular value decomposition is proposed to determine eigenvectors at low frequencies. Discretisation errors are seen to occur if the segment is too large, while round-off errors occur if the segment is too small. This can be overcome by forming a super-segment from the concatenation of two or more segments. The forced response is then considered. The use of a reduced wave basis removes many problems. Direct calculation of the waves excited by a point force is very prone to poor numerical conditioning but can be circumvented by exploiting the orthogonality of the left and right eigenvectors. Numerical examples are presented.
Abstract
MHPS and MHI suggest HP/IP/LP separate casing and one bearing/rotor (one bearing between two casings) type steam turbine. To design this type of shaft arrangement, journal bearing that ...supports high specific load with superior oil film static and dynamic characteristics is demanded. In this paper, it is shown that 610 mm diameter direct lubricated two pads bearing which can operate at high specific load has been developed. Also, it is confirmed that its good bearing characteristics in full scale test.
Free and forced vibrations of a tyre are predicted using a wave/finite element (WFE) approach. A short circumferential segment of the tyre is modelled using conventional finite element (FE) methods, ...a periodicity condition applied and the mass and stiffness matrices post-processed to yield wave properties. Since conventional FE methods are used, commercial FE packages and existing element libraries can be utilised. An eigenvalue problem is formulated in terms of the transfer matrix of the segment. Zhong's method is used to improve numerical conditioning. The eigenvalues and eigenvectors give the wavenumbers and wave mode shapes, which in turn define transformations between the physical and wave domains. A method is described by which the frequency dependent material properties of the rubber components of the tyre can be included without the need to remesh the structure. Expressions for the forced response are developed which are numerically well-conditioned. Numerical results for a smooth tyre are presented. Dispersion curves for real, imaginary and complex wavenumbers are shown. The propagating waves are associated with various forms of motion of the tread supported by the stiffness of the side wall. Various dispersion phenomena are observed, including curve veering, non-zero cut-off and waves for which the phase velocity and the group velocity have opposite signs. Results for the forced response are compared with experimental measurements and good agreement is seen. The forced response is numerically determined for both finite area and point excitations. It is seen that the size of area of the excitation is particularly important at high frequencies. When the size of the excitation area is small enough compared to the tread thickness, the response at high frequencies becomes stiffness-like (reactive) and the effect of shear stiffness becomes important.
Background & Aim: We have already successfully established three-dimensional cultured hepatocyte-like cells (3D-HLCs) with excellent functions from adipose-derived mesenchymal stem cells (ADSCs) via ...a three-step differentiation protocol 1. Regarding the promotion of endothelial cells for hepatic lineage differentiation of ADSCs and their immunological properties have not been evaluated. The aim of this study was to investigated whether the generation of hepatocyte-like organoids (H-organoids) by adding endothelial cells can further improve their liver functions and assess their immunogenicity properties.
ADSCs isolated from healthy donors were differentiated into HLCs according to our established three-step protocol, using recombinant peptide μ-piece from FUJIFILM 1. For addition of HUVECs into 3D-HLCs during different steps, HUVECs were added into HLCs as 1:3 ratio of cell numbers.
Genes represent the liver maturation state and functions were detected by qRT-PCR analysis. Expressions of hepatic maturation proteins were valued by immunofluorescence (IF) staining. Cytochrome P(CYP) 450 metabolism activities and ammonia metabolism tests were used to assess liver functions. Immune properties of H-organoids were analyzed by fluorescence-activated cell sorting analysis.
H-organoids were successfully constructed by adding HUVECs at the beginning of the definitive endoderm stage. Alpha-1 antitrypsin (AAT), carbamoyl-phosphate synthase 1 (CPS1) and apolipoprotein E (APOE), genes that represented the liver maturation state and functions, were further upregulated compared to usual 3D-HLCs (Figure 1). H-organoids showed better CYP3A4 metabolism activities and comparable ammonia metabolism capacities with 3D-HLCs (Figure 2). Moreover, H-organoids express Human leukocyte antigen (HLA) class I, however, those express little HLA class II, CD40, CD80, CD86 and PD-L1. Their immunogenicity properties were not significantly enhanced during the differentiation from ADSCs.
We successfully established H-organoids that showed higher liver functions than previous 3D-HLCs while maintaining lower immunogenicity like ADSCs, which is expected to be a potential source for regeneration medicine.
Urea cycle disorder (UCD) is a rare and incurable metabolic liver disease which presents hepatic encephalopathy due to ammonia-metabolizing enzyme deficiency. We already reported that hepatocyte-like ...cells (HLCs) generated from human adipose-derived mesenchymal stem cells (ADSCs) showed good ammonia metabolism capacity with three-dimensional (3D) culture system (Saito Y, et al. JHBPS 2021). The aim of this study was to clarify the effect of 3D HLCs transplantation (Tx) for UCD model mice.
Human ADSCs (2 × 104) with 0.1 mg/ml human recombinant peptide μ-piece per well were seeded in a 96-well U-bottom plate and then three step differentiation protocol was applied for 21 days as we previously reported. Xenotransplantation of human 200 3D HLCs was performed under kidney capsule of C57BL/6 wild, ornithine transcarbamylase (OTC) deficient (B6EiC3Sn a/A-Otcspf-ash/J), and Citrin deficient (B6.129-Slc25a13tm1Lct) mice with immunosuppressant usage. NH4Cl loading test (5.0 mmol/kg, intraperitoneal injection) was performed at 2/3/4 weeks after Tx. Nephrectomy was performed at 5 weeks after Tx, then mice were sacrificed.
In wild mice, serum ammonia level was 400 umol/L at 30 minutes after NH4Cl loading, and normalized after 4 hours in sham group, however, it was 250 umol/L at 30 minutes, and normalized after 2 hours in Tx group. Such phenomenon were canceled after nephrectomy. A similar trend was observed in both OTC and Citrin-deficient mice (Figure 1). Encephalopathy behavior score was also improved in Tx group. 3D HLCs could be histologically detected with HE without significant lymphocytes invasion, and expression of HLA-Class I and human OTC was immunohistochemically observed at 5 weeks after Tx (Figure 2).
ADSC-derived 3D HLCs showed good hepatic function especially in ammonia metabolism. 3D HLC Tx may be effective as am alternative cell Tx therapy instead of liver organ transplantation for UCD patients.
The clinical and immunoregulatory effects of long-term macrolide antibiotic therapy for patients with chronic lower respiratory tract infections (CLRTI) were investigated. Clinical parameters and ...neutrophil chemotactic mediators in the epithelial lining fluid (ELF) of CLRTI patients (n = 10) were examined before and after 3 months oral administration of roxithromycin (RXM). The in vitro effects of RXM were also examined on the release of these mediators from alveolar macrophages (AM) and neutrophils. Arterial oxygen tension (p<0.05), vital capacity (VC) (p<0.001), %VC (p<0.05) and forced expiratory volume in one second (p<0.01) were improved after RXM treatment, but airway bacteria were not eradicated. Among the mediators, the levels of interleukin (IL)-8, neutrophil elastase (NE) and leukotriene B4 (LTB4) were higher in ELF than in plasma of CLRTI patients and they decreased after RXM treatment (n = 7, p<0.05 for each). RXM concentrations were significantly increased in the bronchoalveolar lavage cells of the treated patients. In in vitro experiments, RXM showed inhibitory effects on IL-8 release from AM and neutrophils. In conclusion, interleukin-8, neutrophil elastase and leukotriene B4 contribute to the neutrophilic inflammation in the airways of chronic lower respiratory tract infection patients and the clinical effects of roxithromycin may, in part, be attributable to the suppression of excess release of the chemotactic mediators from inflammatory cells.
Tetrakis(dimethylamino)ethylene (TDAE)/cat. PdCl2(PhCN)2-promoted reductive coupling of aryl bromides having either electron-donating or electron-withdrawing groups on their para- and/or ...meta-position proceeded smoothly to afford the corresponding biaryls in good to excellent yields. Notably, TDAE is such a mild reductant that easily reducible groups, such as carbonyl and nitro groups, are tolerate. A similar reductive coupling of ortho-substituted aryl bromides did not occur at all. The proper choice of palladium catalysts is essential for the reductive coupling; thus, PdCl2(PhCN)2, PdCl2(MeCN)2, Pd(hfacac)2, Pd2(dba)3, PdCl2, and Pd(OAc)2 were used successively for this reaction, but phosphine-ligated palladium catalysts such as Pd(PPh3)4, PdCl2(PPh3)2, and Pd(dppp) did not promote the reaction. The reductive coupling did not occur with nickel catalysts such as NiBr2, NiCl2(bpy), and Ni(acac)2. The TDAE/cat. palladium-promoted reductive coupling of aryl halides having electron-withdrawing groups took place more efficiently than that of aryl halides substituted with electron-donating groups. A plausible mechanism of TDAE/cat. palladium-promoted reaction is discussed.
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