An analysis of bearingless AC motors

Several types of AC bearingless motors are proposed. These bearingless motors have conventional four-pole stator windings and additional two-pole windings, whose currents produce radial forces acting on the rotor. General expressions of the machine inductances and radial forces are derived for the cylindrical rotor and salient-pole motors. No-load characteristics of laboratory squirrel-cage induction and reluctance-type synchronous bearingless motors are provided. The test motors were successfully driven by the control circuits     

New surface forces apparatus using two-beam interferometry

We designed a new surface forces apparatus for measuring the interactions between two nontransparent substrates and/or in nontransparent liquids. The small displacement of a surface, the bottom one in this study, was measured by the two-beam (twin path) interferometry technique using the phase difference between the laser light reflected by the fixed mirror and that by the mirror on the back of the bottom surface unit. It is possible to determine the distance with a resolution of 1 nm in the working range of 5 microm. This apparatus was successfully applied to measure the forces between mica surfaces in pure water and aqueous KBr solutions.     

Factors associated with serum magnesium and vascular stiffness in maintenance hemodialysis patients

Introduction : We evaluated the associated factors of serum magnesium in patients on maintenance hemodialysis (MHD). Furthermore, we evaluated the relationship between low serum magnesium and arteriosclerosis in these patients. Methods : In 129 patients on MHD, we evaluated the blood levels of magnesium, brachial‐ankle pulse wave velocity (ba‐PWV), ankle‐brachial index (ABI), and intima‐media thickness of the common carotid artery (IMT). Findings : In MHD patients, the serum level of magnesium was significantly correlated with age, calcium, TNF‐α, albumin, and ba‐PWV but not with ABI or IMT. In the multiple regression analysis, albumin (P = 0.0001, β = 0.31) and calcium (P = 0.029, β = 0.18) were selected as significant predictors of the magnesium level in MHD patients. Furthermore, the serum level of magnesium, as well as systolic blood pressure (P = 0.0001, β = 0.32) and age (P = 0.005, β = 0.25), were selected as significant (P = 0.012, β = ?0.22) predictors of ba‐PWV in MHD patients. Discussion : In MHD patients, the serum magnesium level was associated with the serum levels of calcium and albumin. Furthermore, a low serum magnesium level in MHD patients was associated with the index of vascular stiffness.     

Relation between passive smoking at home and dietary intake

Recent attempts to protect hematopoietic progenitor cells from cytarabine (ara-C)-induced toxicity by transfer of the cytidine deaminase (CDD) gene resulted in efficient in vitro inducibility of ara-C resistance. Another enzyme involved in intracellular ara-CTP inactivation is the deoxycytidylate deaminase (dCMPD). We therefore transfected the human dCMPD cDNA gene into murine fibroblasts and investigated the relationship of forced dCMPD expression and resistance induction to ara-C. Several cell lines were established which demonstrated a 1.7-3.5-fold increase in cellular dCMPD activity and an up to 2-fold increase in the IC50 value of ara-C. However, increases in dCMPD activities did not show a positive linear correlation with the induction of ara-C resistance. In addition, CD34 + hematopoietic progenitor cells revealed the highest endogenous dCMPD enzyme levels among different human hematopoietic cells. Thus, despite the documented role for dCMPD in ara-CTP inactivation of certain cell types, these results suggest that the dCMPD gene may prove less useful than the CDD gene as a therapeutic target in attempts to attenuate ara-C-induced bone marrow toxicity.     

BLM (the causative gene of Bloom syndrome) protein translocation into the nucleus by a nuclear localization signal

Bloom syndrome (BS) is a rare genetic disorder characterized by small body size, sun sensitivity, immunodeficiency and a high predisposition to various types of cancer. BLM was identified as the causative gene for BS, and BLM protein is homologous to DNA helicase. There are two putative nuclear localization signals (NLSs) within amino acid residues 1334-1349 in the C-terminus of the BLM protein, which has the distinctive structure of two basic residue arms separated by a spacer. The entire coding or deleted BLM sequences of various sizes were ligated into an enhanced green fluorescent protein (EGFP) vector and transfected into HeLa cells. The EGFP vector harboring the entire BLM coding sequence was transported to the nucleus. The BLM protein truncated at 1341 amino acid, containing an intact helicase domain and only one proximal arm, was not transported to the nucleus. The BLM protein truncated at 1357 amino acid, containing an intact helicase domain and two arms, was transported to the nucleus. The EGFP vector harboring DNA fragments encoding a protein having only the distal arms of basic amino acids in the C-terminus was also transported to the nucleus. The truncated BLM proteins corresponding to previously reported mutated BLM proteins were retained in the cytoplasm or both the cytoplasm and the nucleus as was the EGFP vector with no insert. These results show that the BLM protein translocates into the nucleus and that the distal arm of the bipartite basic residues in the C-terminus of the BLM protein is essential for targeting the nucleus.     

Vibration Suppression of a Flexible Shaft With a Simplified Bearingless Induction Motor Drive

In this paper, we present new strategies of vibration suppression in flexible shaft of a motor with active and passive magnetic forces. Shaft magnetic damping originates from the principle of a bearingless motor having a radial magnetic force generation. Radial force is used for shaft vibration suppression to go through the first critical speed. Simplifications are described in a suppression force system. We propose the elimination of a power source with self-excitation, as well as the elimination of sensors, controllers, and inverters, although the effectiveness is limited.