Acute progressive polyneuropathy in a patient with Waldenstr?m macroglobulinemia

A case of Waldenstr?m's macroglobulinemia (WM) (IgM-kappa type) associated with acute-onset demyelinating peripheral neuropathy is reported. A 49-year-old woman was admitted to our hospital because of general fatigue and recurrent syncope attacks. She was treated with vincristine, cyclophosphamide, epirubicin and prednisolone. By 10th hospital day, her clinical condition improved and serum viscosity was reduced. However, on the 21st hospital day, she suffered from rapidly progressive writing and gait disturbance. Neurological examination showed muscular atrophy and weakness in the distal part of four extremities. Deep tendon reflexes were diminished. There was no sensory deficit. Cerebrospinal fluid was normal. Anti-myelin associated glycoprotein activity of her serum was negative. Both motor and sensory nerve conduction velocities were markedly decreased. Biopsy of sural nerve revealed marked demyelination and onion bulb formation. There was IgM deposition on myelin sheath. Minimal axonal changes excluded the possibility of vincristine neuropathy. Plasmapheresis improved her symptoms, but nerve conduction velocities remained unchanged. Polyneuropathy associated with WM is usually gradual onset and sensory dominant. In this case, associated neuropathy was acute onset, progressive and motor dominant. This type of neuropathy in patients with WM is very rare.     

Electroless copper plating using Fe as a reducing agent

Although the electroless plating method is known to be an effective method for obtaining fine wiring in particular, 1 mol hydrogen gas is generated during 1 mol Cu deposition, and voids are generated in the wiring when electroless Cu plating is applied to fine wiring. To avoid the hydrogen evolution, the possibility of performing electroless Cu plating was confirmed using an inexpensive Fe^II compound as a reducing agent. The bath contains CuSO₄, FeSO₄, NaCl, ethylenediamine, sodium citrate, polyethylene glycol (PEG), and 2,2′-bipyridine. Under optimal conditions, over 1.7 μm of copper deposit with a smooth surface was obtained after 3 h of plating, which did not contain iron as an impurity. The electrical resistivity of the copper film is about 3-4 μΩ cm corresponding to that of electroplated copper films.     

Multi-objective topology optimization of multi-component continuum structures via a Kriging-interpolated level set approach

This paper explores a framework for topology optimization of multi-component sheet metal structures, such as those often used in the automotive industry. The primary reason for having multiple components in a structure is to reduce the manufacturing cost, which can become prohibitively expensive otherwise. Having a multi-component structure necessitates re-joining, which often comes at sacrifices in the assembly cost, weight and structural performance. The problem of designing a multi-component structure is thus posed in a multi-objective framework. Approaches to solve the problem may be classified into single and two stage approaches. Two-stage approaches start by focusing solely on structural performance in order to obtain optimal monolithic (single piece) designs, and then the decomposition into multiple components is considered without changing the base topology (identical to the monolithic design). Single-stage approaches simultaneously attempt to optimize both the base topology and its decomposition. Decomposition is an inherently discrete problem, and as such, non-gradient methods are needed for single-stage and second stage of two-stage approaches. This paper adopts an implicit formulation (level-sets) of the design variables, which significantly reduces the number of design variables needed in either single or two stage approaches. The number of design variables in the formulation is independent from the meshing size, which enables application of non-gradient methods to realistic designs. Test results of a short cantilever and an L-shaped bracket studies show reasonable success of both single and two stage approaches, with each approach having different merits.     

Topological design considering flexibility under periodic loads

Topology optimization has been extensively considered to design the structural configuration for the stiffness maximization and the eigenfrequency maximization. In this paper, we construct a topology optimization method implementing flexibility with the time-periodic loading condition. First, the flexibility in the dynamic periodic loading is formulated using the mutual energy concept. Second, the multi-optimization problem is formulated using a new multi-objective function in order to obtain an optimal solution incorporating both flexibility and stiffness. Next, the topology optimization procedure is developed using the homogenization design method. Finally, some examples are provided to confirm the optimal design method presented here. Received January 18, 1999     

Substrate rotation effects on β-FeSi2 epitaxial film growth using MBE

This study showed that substrate rotation plays an important role in the growth of high-quality β-FeSi₂ epitaxial film on hydrogen terminated Si (1 1 1) substrate using molecular beam epitaxy (MBE). The present work elucidated the substrate rotation effects on morphology, thickness, and purity. Results verified that substrate rotation is essential to grow thicker epilayers with better morphology and compositional uniformity. In addition, purity analyses indicated that substrate rotation increases the concentration of non-metallic impurities (H, C, and O), but does not further introduce metallic impurities into β-FeSi₂ films.     

Effect of CNTs on Activation Volume and Mobile Dislocation Exhaustion Rate of CNTs/Al under Compression Loading

In this study, stress relaxation compression tests were performed to investigate the strain rate sensitivity, activation volume and mobile dislocations in carbon nanotubes/aluminum (CNTs/Al) composites. The results reveal that, with the addition of CNTs, the strain rate sensitivity of CNTs/Al increased. Meanwhile, a smaller V^* of CNTs/Al compared with pure Al was attributed mainly to the CNT-Al interfaces and partly to the increased forest dislocations cutting activities in grain interior, which was related to the tendency of short ranges order formation during plastic deformation. The incorporation of CNTs also improved the dislocation storage capability and reduced the dislocation velocity, leading to a lower mobile dislocation exhaustion rate.     

Gelation of gellan – A review

Gellan is an anionic extracellular bacterial polysaccharide discovered in 1978. Acyl groups present in the native polymer are removed by alkaline hydrolysis in normal commercial production, giving the charged tetrasaccharide repeating sequence: → 3)-β-d-Glcp-(1 → 4)-β-d-GlcpA-(1 → 4)-β-d-Glcp-(1 → 4)-α-l-Rhap-(1 →. Deacylated gellan converts on cooling from disordered coils to 3-fold double helices. The coil–helix transition temperature (T_m) is raised by salt in the way expected from polyelectrolyte theory: equivalent molar concentrations of different monovalent cations (Group I and Me₄N⁺) cause the same increase in T_m; there is also no selectivity between different divalent (Group II) cations, but divalent cations cause greater elevation of T_m than monovalent. Cations present as counterions to the charged groups of the polymer have the same effect as those introduced by addition of salt. Increasing polymer concentration raises T_m because of the consequent increase in concentration of the counterions, but the concentration of polymer chains themselves does not affect T_m. Gelation occurs by aggregation of double helices. Aggregation stabilises the helices to temperatures higher than those at which they form on cooling, giving thermal hysteresis between gelation and melting. Melting of aggregated and non-aggregated helices can be seen as separate thermal and rheological processes. Reduction in pH promotes aggregation and gelation by decreasing the negative charge on the polymer and thus decreasing electrostatic repulsion between the helices. Group I cations decrease repulsion by binding to the helices in specific coordination sites around the carboxylate groups of the polymer. Strength of binding increases with increasing ionic size (Li⁺ < Na⁺ < K⁺ < Rb⁺ < Cs⁺); the extent of aggregation and effectiveness in promoting gel formation increase in the same order. Me₄N⁺ cations, which cannot form coordination complexes, act solely by non-specific screening of electrostatic repulsion, and give gels only at very high concentration (above ∼0.6 M). At low concentrations of monovalent cations, ordered gellan behaves like a normal polymer solution; as salt concentration is increased there is then a region where fluid “weak gels” are formed, before the cation concentration becomes sufficient to give true, self-supporting gels. Aggregation and consequent gelation with Group II cations occurs by direct site-binding of the divalent ions between gellan double helices. High concentrations of salt or acid cause excessive aggregation, with consequent reduction in gel strength. Maximum strength with divalent cations comes at about stoichiometric equivalence to the gellan carboxylate groups. Much higher concentrations of monovalent cations are required to attain maximum gel strength. The content of divalent cations in commercial gellan is normally sufficient to give cohesive gels at polymer concentrations down to ∼0.15 wt %. Gellan gels are very brittle, and have excellent flavour release. The networks are dynamic: gellan gels release polymer chains when immersed in water and show substantial recovery from mechanical disruption or expulsion of water by slow compression. High concentrations of sugar (∼70 wt % and above) inhibit aggregation and give sparingly-crosslinked networks which vitrify on cooling. Gellan forms coupled networks with konjac glucomannan and tamarind xyloglucan, phase-separated networks with kappa carrageenan and calcium alginate, interpenetrating networks with agarose and gelling maltodextrin, and complex coacervates with gelatin under acidic conditions. Native gellan carries acetyl and l-glyceryl groups at, respectively, O(6) and O(2) of the 3-linked glucose residue in the tetrasaccharide repeat unit. The presence of these substituents does not change the overall double helix structure, but has profound effects on gelation. l-Glyceryl groups stabilise the double helix by forming additional hydrogen bonds within and between the two strands, giving higher gelation temperatures, but abolish the binding site for metal ions by changing the orientation of the adjacent glucuronate residue and its carboxyl group. The consequent loss of cation-mediated aggregation reduces gel strength and brittleness, and eliminates thermal hysteresis. Aggregation is further inhibited by acetyl groups located on the periphery of the double helix. Gellan with a high content of residual acyl groups is available commercially as “high acyl gellan”. Mixtures of high acyl and deacylated gellan form interpenetrating networks, with no double helices incorporating strands of both types. Gellan has numerous existing and potential practical applications in food, cosmetics, toiletries, pharmaceuticals and microbiology.     

Effects of fermentation conditions and soybean peptide supplementation on hyaluronic acid production by Streptococcus thermophilus strain YIT 2084 in milk

To increase the hyaluronic acid (HA) yield from Streptococcus thermophilus YIT 2084, fermentation conditions (pH, temperature, agitation, aeration) were optimized in milk-based medium, and the effects of supplemental soybean peptides, which have different molecular weight distributions, were determined. HA production was enhanced to approximately 100 mg/l at pH 6.8 and 33–40 °C. Agitation speed and aeration rate slightly affected HA production. Soybean peptides including those of high molecular weight (approximately 27 to 130 kDa) further increased HA production to 208 mg/l under the optimal condition (pH 6.8, 35 °C, 100 rpm), which was 20-fold greater than non-optimal condition. HA production was no longer related to the specific growth rate. The HA produced under the optimal condition included a large amount of high-molecular-weight fraction of 100 to 2000 kDa, compared with under the basal condition without optimization.     

Molecular structures of gellan gum imaged with atomic force microscopy (AFM) in relation to the rheological behavior in aqueous systems in the presence of sodium chloride

Aqueous solutions of gellan gum with comparable molecular mass but with different acyl contents were investigated by atomic force microscopy and rheological measurements in the presence of sodium chloride (NaCl). Results obtained were discussed in relation to our previous report using potassium chloride (KCl) as an added salt. For a low-acyl sample, continuous fibrous network structures were identified microscopically as in the case of KCl. The network structures were more heterogeneous than those formed with KCl in terms of the height distribution of molecular assemblies. Rheological thermal hysteresis between sol–gel transitions was detected as in the case of KCl. The storage modulus (G′) of the gelled system was ca. 15% of the corresponding data with KCl at 20 °C. For a high-acyl sample, no continuous network structures were identified but branches with observable ends were identified as in the case of KCl. The hysteresis was less evident than the corresponding data with KCl and for the low-acyl sample with NaCl. Also, G′ values at 20 °C were ca. 30% and 20% of the corresponding data with KCl and for the low-acyl sample with NaCl, respectively. Continuousness and homogeneity of network structures related to the hysteresis and elasticity of the system, respectively.