Formation of electroless barrier and seed layers in a high aspect ratio through-Si vias using Au nanoparticle catalyst for all-wet Cu filling technology

An all-wet process was achieved using electroless deposition of barrier and Cu seed layers for fabrication of a high aspect ratio through-Si via (TSV). Formation of a thin barrier metal layer of Ni–B, Co–B and Co–W–B is possible using a Au nanoparticle (AuNP) catalyst, which is densely adsorbed on the SiO₂ of the TSV sidewall. A silane coupling agent of 3-aminopropyl-triethoxysilane is effective for enhancement of the density of adsorption for AuNP. A conformal electroless Cu layer is deposited on the barrier layer by displacement plating without a catalyst. The adhesion strength between the electroless barrier layer and the SiO₂ substrate is increased by annealing at 300 °C. These results strongly suggest that an all-wet process for the formation of Cu-filled TSV with a high aspect ratio is practically possible.     

The Effect of Heterozygous Mutation of Adenylate Kinase 2 Gene on Neutrophil Differentiation

Mitochondrial ATP production plays an important role in most cellular activities, including growth and differentiation. Previously we reported that Adenylate kinase 2 (AK2) is the main ADP supplier in the mitochondrial intermembrane space in hematopoietic cells, especially in the bone marrow. AK2 is crucial for the production of neutrophils and T cells, and its deficiency causes reticular dysgenesis. However, the relationship between ADP supply by AK2 and neutrophil differentiation remains unclear. In this study, we used CRISPR/Cas9 technology to establish two heterozygous AK2 knock-out HL-60 clones as models for reticular dysgenesis. Their AK2 activities were about half that in the wild-type (WT). Furthermore, neutrophil differentiation was impaired in one of the clones. In silico analysis predicted that the obtained mutations might cause a structural change in AK2. Time course microarray analysis of the WT and mutants revealed that similar gene clusters responded to all-trans retinoic acid treatment, but their expression was lower in the mutants than in WT. Application of fructose partially restored neutrophil differentiation in the heterozygous knock-out HL-60 clone after all-trans retinoic acid treatment. Collectively, our study suggests that the mutation of N-terminal region in AK2 might play a role in AK2-dependent neutrophil differentiation and fructose could be used to treat AK2 deficiency.     

Experimental investigation of discharge characteristics of a surface‐wave‐produced planar plasma

Experimental investigations of the discharge characteristics of planartype surfacewaveproduced plasmas (SWP) have been carried out. On this apparatus, the efficiency of microwave power absorption into the plasma depends strongly on the thickness of the dielectric window. Especially at a thickness of 12 mm, it has been found that more than 80% of microwave power is absorbed into the plasma. In order that the uniform power absorption is brought about effectively in a wide range of gas pressures, the dielectric waveguide that is placed above the dielectric window needs the air gap between them. These experimental results will enable us to improve the apparatus configuration to achieve better operational performances of surface wave plasmas. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 9–18, 2002     

Site-directed mutagenesis of active site contact residues in a hydrolytic abzyme: evidence for an essential histidine involved in transition state stabilization

Specific molecular interactions involved in catalysis by antibody 6D9 were investigated by site-directed mutagenesis. The catalytic antibody 6D9, which was generated against a transition state analog (III), hydrolyzes a non-bioactive chloramphenicol monoester derivative (I) to produce chloramphenicol (II). Construction of a three-dimensional molecular model of 6D9 and sequence comparison within a panel of related antibodies suggested candidates for catalytic residues, His (L27d), Tyr (L32), Tyr (H58) and Arg (H100b); these were targeted for the site-directed mutagenesis study. The Y-H58-F and R-H100b-A mutants possessed catalytic activities comparable to that of the wild-type, and the Y-H58-H and Y-L32-F mutant displayed an approximately fivefold decrease in k(cat)/Km. In the transition state analysis, the plots of logK(TSA) versus log(k(cat)/Km) for the mutants are linear, with a slope of approximately 1.0, indicating that the entire hapten-binding energy in the mutants is also utilized to bind the transition state and to accelerate the catalysis. In addition, a dramatic change in the catalytic activity was observed when the histidine residue (27d) in the CDR1 light chain was replaced with alanine. The H-L27d-A mutant had no detectable catalytic activity. This mutation led to a large, 40-fold reduction in transition state binding, with no change in substrate binding. Coupled with the previous kinetic studies and chemical modifications of the intact 6D9 antibody, this mutagenesis study has demonstrated that His L27d plays an essential role in stabilization of the transition state, the mechanism of catalysis by the 6D9 antibody.     

Development of a distributed power outage scheduling system by using bee‐gent

The Power Outage Scheduling Problem is a distributed constraint satisfaction problem in which scattered local power stations have to make schedules that are consistent with one another. However, synchronous backtrack algorithms, a well‐known method for distributed constraint satisfaction problems, have difficulty handling rapid schedule adjustments and impartial assignment of power station schedules. Thus, we propose two kinds of heuristics: parallel assignment and multiple priority strategies. We also developed a distributed system for the power outage scheduling problem which makes use of the above heuristics in order to ensure efficiency. The system is based on Bee‐gent (Bonding and Encapsulation Enhancement aGENT framework) and consists of schedulers for each power station and mediation agents which have cloning and merging functions to support the implementation of the heuristics. The result of the experiment shows an improvement when handling rapid adjustment and impartiality issues and indicates that this improvement is provided with reasonable computational overhead. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 139(3): 62–72, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.1161     

B-cell lymphoma of mucosa-associated lymphoid tissue of the thymus: a report of two cases with a background of Sj?gren's syndrome and monoclonal gammopathy

Two rare cases of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) arising in the thymus are reported. Both patients (a 61-year-old man and a 75-year-old woman) were suffering from Sj?gren's syndrome and immunoglobulin (Ig)A kappa monoclonal gammopathy. Mixed IgA-IgG cryoglobulinemia was also present in the male case. Tumor cells expressed IgA and kappa antibody reactive proteins identical with serum IgA kappa M. Moreover, we could demonstrate rearrangements of the immunoglobulin heavy and light chain genes, which supported the monoclonal origin of tumor cells. Immunological abnormalities improved after thymectomy in one case in which the tumor cells were confined to the thymus, but not the other with regional lymph node involvement, suggesting a causal role for the tumor. MALT lymphomas of the thymus thus appear to be associated with immunological disorders such as Sj?gren's syndrome or monoclonal gammopathy.     

Strength Development in Phosphate-Bonded Calcium Aluminate Cements

The chemical reaction at room temperature between calcium aluminate cement (CAC) and NH₄H₂PO₄-based fertilizer solution causes the formation of ammonium calcium pyrophosphate (AmCPP) as an amorphous cementitious phase. This phase was responsible for the development of strength in rapid-setting phosphate-bonded cement (PBC) specimens. Hydrothermal treatment of PBC at 200°C led to phase transformations of AmCPP and CAC into crystalline hydroxyapatite as the major phase and anorthite as the minor one. The moderate growth of these interlocked crystals in the interspaces of amorphous phases played an important role in creating a dense microstructure, thereby conferring a very high strength to the PBC. In contrast, an excessive crystal growth, which caused the formation of porous microstructure, resulted in a reduction in strength.     

Sugar-binding sites with specificity for glucosamine in the guinea pig middle ear mucosa

Glucosamine-binding sites were detected in Lowicryl K4M-embedded guinea pig middle ear mucosa by electron microscopy, using glucosaminyl bovine serum albumin. Incubation of ultrathin tissue sections with gold-labeled glucosaminyl bovine serum albumin (GlcN/BSA/gold) resulted in binding mainly on cilia, microvilli, rough endoplasmic reticulum and nuclei. The sugar binding was not inhibited after ultrathin sections had been digested with trypsin or neuraminidase. Various carbohydrates and glycoconjugates were tested as competitive inhibitors of GlcN/BSA/gold labeling on the tissue sections. The sugar specificity range detected by the glucosamine-binding sites included glucosamine, N-acetylglucosamine, mannose and fucose, whereas N-acetylgalactosamine, galactose and glucose were not detectable. A series of endotoxic substances such as Salmonella minnesota Re595 lipid A complex with BSA and lipopolysaccharides (LPS) derived from Escherichia coli 055:B5 or S. minnesota Re595 also competed with GlcN/BSA/gold binding. This indicates that the lipid A backbone glucosamine or other carbohydrate portions of LPS is a part of the structure recognized by glucosamine-binding sites.