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Recent curriculum reforms underline mathematical activity related to proof validation , but few studies have explicitly addressed proof validation at the secondary school level. This chapter reports on our study of this issue. We suggest a specific kind of task for introducing proof validation in secondary school geometry and define the meanings of proof validation and proof modification in terms of Lakatos’s notion of the local counterexample . We briefly report on a classroom-based intervention implemented using such tasks in a lower secondary school in Japan. We then analyze the results of a task-based questionnaire conducted after the intervention to investigate how well the students did in proof validation and modification. The analysis shows that student failure in proof validation arose mainly from their difficulty with producing diagrams that satisfied the condition of the proof problem.

Parasporin is the cytocidal protein present in the parasporal inclusion of the non-insecticidal Bacillus thuringiensis strains, which has no hemolytic activity but has cytocidal activities, preferentially killing cancer cells. In this study, we characterized a cytocidal protein that belongs to this category, which was designated parasporin-5 (PS5). PS5 was purified from B. thuringiensis serovar tohokuensis strain A1100 based on its cytocidal activity against human leukemic T cells (MOLT-4). The 50% effective concentration (EC50) of PS5 to MOLT-4 cells was approximately 0.075 μg/mL. PS5 was expressed as a 33.8-kDa inactive precursor protein and exhibited cytocidal activity only when degraded by protease at the C-terminal into smaller molecules of 29.8 kDa. Although PS5 showed no significant homology with other known parasporins, a Position Specific Iterative-Basic Local Alignment Search Tool (PSI-BLAST) search revealed that the protein showed slight homology to, not only some B. thuringiensis Cry toxins, but also to aerolysin-type β-pore-forming toxins (β-PFTs). The recombinant PS5 protein could be obtained as an active protein only when it was expressed in a precursor followed by processing with proteinase K. The cytotoxic activities of the protein against various mammalian cell lines were evaluated. PS5 showed strong cytocidal activity to seven of 18 mammalian cell lines tested, and low to no cytotoxicity to the others.

Bacillus thuringiensis A1470 produces multiple proteins with similar molecular masses (~30 kDa) with cytotoxicity against human cell lines. One that was previously identified, parasporin-4, is a β-pore-forming toxin. The N-terminal sequence of a second cytotoxic protein was identical to a partial sequence of parasporin-2 produced by B. thuringiensis A1547. PCR was performed on total plasmid DNA from A1470 by using primers for parasporin-2 to amplify a gene which was then cloned. The cloned gene differed from A1547 parasporin-2 by 8 bp and the predicted protein differed by four amino acids. The gene was expressed in Escherichia coli, and the cytotoxic activities of the recombinant protein against four human cell lines (MOLT-4, Jurkat, HeLa, and HepG2) were similar to those of A1547 parasporin-2. We then confirmed that the A1470 strain simultaneously produces parasporin-2 and parasporin-4.

Despite blood culture's usefulness in antimicrobial therapy, fewer blood cultures and the infrequency of more than 1 set in cultures appear to be problems in Japan. Since June 2007 infection control team (ICT) recommended more than 1 set in blood sampling and intervention in positive blood culture, coagulase negative Staphylococci (CNS) has frequently been isolated from blood culture and its clinical significance is often difficult to judge. To determine the effect of ICT intervention, we evaluated the number of blood culture specimens, the frequency of more than 1 set in all blood culture specimens, and decision-making on antimicrobial treatment for CNS isolated retrospectively from blood. The study was divided into term I in August 2007 to July 2008, term II in August 2008 to July 2009, and term III in August 2009 to February 2010. We also analyzed how physicians treated infection or its suspicion after CNS and its drug susceptibility. The monthly number of blood culture specimens increased from 40.3 to 51.6 between terms I and III. The frequency of more than 1 set in a single blood culture session rose significantly from 67% to 89% between these terms (p < 0.001). The number of indeterminate also dropped cases significantly during these 2 terms from 27% to 6% (p = 0.017). Infection or suspected infection cases--45 of 49--had central vein catheter implantation. Inappropriate treatment by physicians in these cases also dropped significantly from 85% (11/13) to 45% (5/11) (p = 0.043) during the same 2 terms. ICT Intervention may thus increase the number of blood culture specimens, enable more than 1 set in blood sampling, make it easier to judge the presence of infection, and increase appropriate treatment by physicians. We thus believe that the quality of antimicrobial treatment could be improved through education such as ICT action.

Didodecyldimethylammonium bromide (DDAB) is widely used for an efficient delivery system into mammalian cells. However, the biological activities of DDAB nanoparticles in mammalian cells are insufficiently understood. The purpose of this study was to establish a critical role of DDAB in cellular response. Here, we demonstrate that DDAB is a potent inducer of cell death in a wide range of tumor cell lines, wherein leukemia cells (HL-60 and U937) and neuroblastoma cells (Neuro2a) were more sensitive to DDAB than carcinoma cells such as HepG2 and Caco-2 cells. Moreover, in HL-60 cells, treatment with DDAB led to increased numbers of apoptotic cells with fragmented DNA (99.6%) and high levels of caspase-3 activation in comparison to that with actinomycin D. Cotreatment with a caspase-8 inhibitor (Z-IETD-FMK) or a polyethylene glycol (Mr 2000) (PEG 2000) effectively prevented the activation of caspase-3 induced by DDAB. These results suggest that DDAB can trigger caspase-3-mediated apoptosis through the extrinsic caspase-8 pathway and cytotoxic pore formation in cell membrane. Therefore, the present findings provide new insight into the biological activity of DDAB to induce caspase-mediated apoptosis.

The thermal degradation and the combustion tests of epoxy resins (prepolymer) whose molecular weights are from 1,650 to 50,000 have been conducted. From the result of the vertical firing experiments of epoxy resins with different molecular weight, it was found that there is a molecular weight region where combustion do not continued because volatile gas components are hardly generated by burning. In the thermo-gravimetric analyses, it was observed that the degradation behaviors did not change for the difference of the molecular weight. In the relation between the molecular weight and combustibility, it was observed that the molecular weight distribution did not change in the samples that did not burn. On the other hand, it was seen that molecular weight lowered in the burned sample. These results suggest that there is a possibility that the combustibility can be controlled by adjusting the molecular weight.

A study was conducted on the combustion product gases generated when polyurethane, other polymeric materials, and wood are burnt, and their safety. Compared to other materials, the ignition and combustion times of PU were short, which showed that it is a highly combustible material. Regarding its toxicity during combustion, CO and HCN etc. of isocyanate group origin are particularly viewed as problematic. From the results of the examination of the risk factors during fires, the lengths of time for the most influential risk factor in each sample to reach the fatal dose were in the order of PU foam, wood, PA66, PP, PC, and PU. In the case of PU, the emission of CO and HCN, which are considered particularly problematic during fires, was not great even when compared to PP, PC, and PA66 etc. often used in daily life. However, the risk increases when it is in the state of foam because the combustion speed is faster.

The flame retardancy of polybutylene terephthalate (PBT) was studied focusing on the effect of various oxides. Thermo-gravimetric analysis, pyrolysis/gas chromatography/mass spectrometry, and elemental analysis (EA) were used to analyze the flame retardancy, which were observed through the UL-test and a cone calorimeter. Many oxides influenced the flame retardancy and some of them could suppress the flammability of PBT. In particular, the blended-PBTs with ZnO and V2O5 accelerated the degradation and the edges of oxygen consumption were shorter than neat-PBT although the flammability became poorer. The quantitative analysis of the scission products and the results of EA showed that hydrolysis, successive dehydration, and other various reactions changed the scission route to generate less flammable products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

ポリエチレン(PE)，ポリプロピレン(PP)，ポリブテン(PB)の 3 種のポリオレフィンおよびポリスチレン(PS)の燃焼炎の位置と熱分解生成物の関係について燃焼状態観察ならびに熱分解生成物の分析とそれら相互の関係から研究を行った．垂直燃焼の場合，燃焼時の炎は PE で下方に移動し，PS では上方に移動した．PP と PB は PE と PS の中間の状態であった．熱分解の状態と生成物分布を測定したところ，PE では低分子量に特徴的な分解生成物が観測されたが，全体としては高分子量の生成物が多かった．これに対して PS では熱分解生成物の種類が限定され，沸点が 170℃ である単量体がモル比で 0.73，燃焼熱の割合で 54%を占めていた．燃焼熱加重平均沸点(CHWABP)と垂直燃焼の炎の位置の関係を求めたところ，上限平均位置は燃焼熱加重平均沸点に比例しており，下限平均位置は PE と PS に明確な差が見られた．炎の位置と高分子材料を使用した場合の火災に対しての安全性は密接に関係し，熱分解生成物の分布によってより安全な設計が可能になると考えられた．

The relation between the thermal decomposition and flammability of polynorbornene (PNB) synthesized by addition polymerization was analyzed. In a small-sized vertical combustion test, the PNB did not combust or drip, and the first ignition was extinguished in the combustion test with a cone calorimeter. The decomposition products of PNB were of some low molecular weight compounds with random scissions on the norbornene structure, and alkene (with 12 carbons in the PNB used in this study) was selectively generated by retro-Diels–Alder reaction. When the zeolite was added, the decomposition was accelerated and low molecular weight products increased, especially H2O. These results suggested that the flammability of the thermal decomposition gas was caused by the zeolite, which changed the composition of decomposition products. The lower flammability limits calculated in Le Chatelier's equation were increased from 0.9 to 1.3 by the zeolite. The flame retardancy of PNB was observed because the amount of H2O as an inert gas and the lower flammability limit was increased.

Scratch tests were carried out to examine the influence of gas pressure during ion bombarding on adhesion between CrN coatings and aluminum alloy using nitrogen and argon gas. The critical load clearly increased with increasing the nitrogen gas pressure. However, argon gas pressure hardly affected the critical load. The result of SIMS showed that ion bombardment in nitrogen gas generated high Cr content layer at the aluminum substrate surface and the Cr content increased with increasing the pressure. The ion bombardment in argon gas generated low Cr content surface layer and the pressure hardly affected the critical load. Thus, the high Cr content layer by ion bombardment in the high nitrogen pressure improved adhesion between CrN coatings and aluminum alloy

The contribution of the shape and size of polymers towards ignition for four kinds of polymers, PP (polypropylene), HIPS (rubber reinforced polystyrene), ABS (acrilonitril-butadiene-styrene copolymer) and PC (bisphenor-A type polycarbonate) was studied. The critical heat flux (CHF), which means that the specimen ignites after infinite time, depended on the shape and kind of polymer at the plane position heating. But it was not affected by these conditions at the side position heating. The CHF and other phenomena of ignition were analyzed and the two regions in one of which the shape and the kind of polymer affects them and in another region they was not affected. It will be useful to design electrical parts that reduce fire risks. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

非相溶性アロイであるポリカーボネート(PC)/ポリ乳酸(PLA)の燃焼挙動とケージ効果の研究を行った．PC と PLA を 60:40，30:70 の重量比で調整し，水平燃焼による熱流束を測定した結果，PLA に類似した結果を得た．垂直燃焼では PC および PLA 単独の高分子材料とは大きく異なる挙動を示した．この差を明らかにするために熱重量分析を行ったところ，2 段の熱重量曲線が得られ，PC は PLA の存在によって分解が加速されることがわかった．熱分解生成物の定性・定量結果によると燃焼に主として寄与する化合物は PC 由来ではビスフェノール A，PLA 由来ではアセトアルデヒドであり，PC と PLA の組成の変化に比例して分解生成物の組成が変化することがわかった．以上の結果と垂直燃焼実験の観測から，PC/PLA アロイの燃焼においては PC が PLA を立体的に保持する効果(ケージ効果)により，燃焼性が増大することが明らかになった．

The morphology observed on the fracture surfaces of polystyrene (PS), high-density polyethylene (HDPE), polyphenyleneether (PPE) and polycarbonate (PC) was studied. The stresses were added by cyclically mechanical load whose frequencies are from 0.02 Hz to 1.4Hz and thermal stress load where the temperature ranges were from −55 to 125°C and from −40 to 90°C. The frequency at the cyclically mechanical test was decided from actual response experiments that had been carried out prior to the fatigue test. The specimen for the thermal stress fatigue test was bound between two copper boards and the inner stress was caused by the difference of the coefficient of the thermal expansion. The fatigue lives of the four polymers were in the range from around 400 to 9000cycles, and the less the entanglement density, the shorter the life. The four polymers showed characteristic patterns on the fracture surface. The pattern of the most fragile polymer, PS, was mirror-like and it did not change in the wide range of frequencies. The fracture surfaces of ductile polymers such as PE, PPE and PC were complicated but regular. In particular, the dimpled pattern of the PE surface and the striated one of PPE were noteworthy because the patterns suggested the mechanism of fatigue fractures. In the case of PE, small crystal slides by the cyclic load and microscopic destruction occur. In PPE, the strong entanglement controls the collapse in a wide area and the striation and other regular patterns are due to the destruction in a limited area.

The thermal behaviors and the flame-retardancy of styrene–ethylene–butadiene–styrene–block copolymer containing various additives were studied. The combustion was measured by the Underwriter laboratory (UL) test and cone calorimeter test and thermogravimetric analysis and program-mass spectroscopy were applied to analyze the thermal behaviors. The blend with halogen additives showed the best result in the UL test. However, the blend with red-phosphorous was the best in the cone calorimeter test. As the styrene sequence in the copolymer tended to degradate at a lower temperature, the major scission products spouted out from the polymer surface originated from polystyrene. The shorter the ignition times of the blends with red-phosphorous were, the lower the peak heat release rates were. It was an interesting phenomenon because it suggested that the chemical structure of the residue changed to more stable polymers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 156–161, 2007

新しい手法によって高分子材料の燃焼性を測定する試作機を開発し，12 種類の高分子材料について燃焼データを取得するとともに，特徴的な燃焼挙動が見られた EVA(エチレン-酢酸ビニル共重合体)について解析を加えた．試作機は高分子材料の試験片を垂直に置き，バーナーで加熱，着火し，燃焼中の燃焼熱，重量変化などを測定しうる．12 種類の対象材料について燃焼中の重量減少速度，総発熱量，発熱速度，燃焼残渣量などの基礎データに加えて，ドリップ時間，ドリップ残渣量など火災防止に有用な実用特性も得ることができた．また，これらのデータからガス化重量を算出し，理論燃焼熱との比較を行った．その結果，燃焼の挙動が大きく異なる二つのグループに分かれること，ランダムにドリップする材料と周期的なドリップが認められる材料があること，理論燃焼熱に対して明瞭に燃焼熱が低い材料があることがわかった．燃焼時の重量変化が顕著であった EVA について熱重量変化から分解生成物と燃焼の関係について解析した．

ポリアミド 66(PA66)に塩化第二銅・二水和物を微量添加して，耐熱性の変化を観測するとともに高分子構造についての研究を行った．その結果，銅を 35 ppm 以上添加すると熱安定性に変化が見られたが，濃度と安定性には強い比例関係は見られなかった．分子量は銅を添加しても低下するが，その程度は小さかった．吸水性は銅の添加によって増大した．赤外分光分析と NMR の測定では構造的に変化が見られた．熱を加えることによって主鎖の開裂が見られ，開裂の程度は銅によって抑制される．銅が親水性基を有する PA66 中に均一に分散したとして，銅 1 原子が占有する体積に銅原子が半分拡散する時間が 2～200 μs 程度と短いことによる，アミド結合周辺の安定化効果と高分子鎖全体に及ぼす立体構造の変化が原因の一つになっていると考えられる．

微量な超強酸塩(パーフロロブタンスルホン酸カリウム(FBS))を添加したポリカーボネート(PC)の熱分解と燃焼挙動について検討を行った．100 ppm から 10000 ppm という微量な添加物の影響を見ることから特に再現性に留意して実験を行った．その結果，100 ppm 程度の FBS の添加によって PC の燃焼が抑制され，UL 垂直燃焼実験において再現性よく 5 s 以内で自己消炎することが明らかになった．FBS と類似のパーフロロメタンスルホン酸カリウム(FMS)でも効果が見られた．また熱重量分析を行ったところ FBS を添加することによって 5%および 50%重量減少温度が低下し，700℃ における熱分解残渣の減少が見られた．微量添加の影響，重量減少温度の低下，および熱分解残渣の減少が難燃性に寄与するという従来の知見と異なる結果が得られた．

ポリ乳酸(PLA)，ポリブチレンテレフタレート(PBT)，ポリエチレンテレフタレート(PET)およびポリエチレンナフタレート(PEN)の熱による主鎖開裂について研究を行った．熱重量分析，熱分解ガスクロマトグラフィー質量分析および元素分析によって分解生成物と残渣の分析を行った．また，使用した高分子に対して分解生成物と残渣の構造から計算した炭素，水素，酸素の積算値から分析の精度を検討した．ポリエステルが熱分解する場合の切断箇所の切断確率は PLA では C=O の前後が 48%, 47%であった．これに対して PBT では PLA で切断する二箇所の切断確率は 14%と低く，86%がカルボキシル基とアルキル基の結合で開裂した．PET, PEN でも PBT と同様の傾向が見られたが，カルボキシル基とアルキル基の結合の切断確率はそれぞれ 59%, 49%と低かった．ポリエステルの構造によって分解生成物および切断確率は大きく異なったが分解経路は，1)分解生成物の安定性，2)擬似六員環の形成数，に依存し，ポリエステルの熱分解が統一的なメカニズムでおこる可能性が示唆された．

I appreciate the thoughtful comments from Dr. Leopoldo Palma [1] on our research about cytotoxic protein parasporin-5 produced by Bacillus thuringiensis (BT) A1100 strain [2]. [...]

A novel gene encoding a leukemic cell-killing parasporal protein, designated parasporin-4, was cloned from an isolate of Bacillus thuringiensis serovar shandongiensis. The amino acid sequence of the parasporin-4, as deduced from the gene sequence, had low-level homologies of

We bave fabricated a naocomposite consisting of a crystalline polymer and fine metal part cles The intercalation of alkali metal ions into the layered polymer crystals, which were prepared by the solid state polymerization of dodecylammonium muconate, was achieved by heterogeneously stirring the reacting solid polymers in a solution of sodium hydroxide in methhanol at room temperature. Anion exchange reaction was similarly carried out in a silver nitrate solution, which was follwoed by photoreducature. An ion exchange reaction was similarly carried out in a silver nitrate solution, which was followed by photomlucedyction, leading to the formation of fine silver particles in the crystalline polymer (the organic matrix). By coatrornng the amount of silver ions introduced. we have fabricated an organic/inorganic nanocomposite containing silver nanoparticles with well controlled size and distribution, the characteristics of which were measured by transmission electron microphotography, UV-visible diffuse reflectance spectroscopy and a small-angle X-ray scattering method.

高分子材料の内, 汎用プラスチックとしてPP (polypropylene), HIPS (high impact polystyrene) を, エンジニアリング・プラスチックとしてPC (polycarbonate) を, さらに中間的な用途に使用されるABS (acrylonitrile-butadiene-styrene copolymer) を選択し, その着火性を調べた. 熱重量分析と燃焼実験とともに, 特に試料形状と着火特性について火源との間の立体的位置関係を制御し平面位 (加熱源が試料の平面の部分を照射する位置) と側面位 (同じく側面部分を照射する位置) で検討を行った. 平面位では試料の厚さに対して着火時間の逆数と照射熱流束が直線関係を示し, またその傾きが厚さによらず同一であったが, 側面位では交点が得られた. また平面位では高分子の種類によって着火に至る臨界熱流束が変化するが, 比熱で補正することによって臨界熱流束は高分子の種類によらないことが明らかになった. 側面位の着火現象は平面位より複雑であったが, 交点から求めた着火までの総熱量はHIPS, ABS, PCでほぼ同一の値として約1200kJ/m2が得られた.

4-フルオロ-4'-ヒドロキシルベンゾフェノン (FHB) を重合して得られるポリエーテルケトン (PEK) を重合反応の出発物質として重合することを試みた. その結果, 炭酸カリウムを重合助剤として用いた場合, 溶液中でのPEKの反応速度は分子量の増大の絶対値を基準にした場合にはFHBの重合より大きい値が得られた. 固相における重合でもカリウム濃度が高い条件では同等程度の値を得た. 高分子重合では重合する対象物の分子量が大きいので, 単量体を使用して重合する場合に比較して同一の反応速度でも分子量の絶対値の増大は大きくなる. 固相における重合速度は7.1～33.5×10-3L・mol-1・s-1であり, 活性化エネルギーは25.6kJ・mol-1であった. したがってPEKの重合は拡散律速であると考えられるが, 狭い反応場における高分子末端および添加物の活量が高いことが速い反応速度を得た理由と考えられる.

大環状包接化合物の中でも特徴的な構造を有するCalix[8]areneおよびその遷移金属錯体を調整し, polypropylene (PP), polycarbonate (PC) およびpolybutylene terephthalate (PBT) に添加して燃焼特性の変化を測定した. 錯形成定数をEDTAのような一般的な有機配位子の場合と比較したところ, 錯形成率はイオン半径に比例し, 銅イオンの場合, 85%ともっとも高い錯形成率を示した. 調整したCalix[8]areneおよび錯体を1～5wt%程度, 高分子材料に添加して燃焼実験, 熱流束測定および熱重量分析を行った. その結果, 燃焼実験ではFeおよびCu錯体に燃焼抑制効果が見られた. 特にPCの場合, Fe錯体の抑制効果が顕著で着火時間が長くなり, 約4秒で消炎した. PPおよびPBTにおいては燃焼実験での差が小さかったが, 燃焼時の熱流束には差が認められた. またPBTにCu錯体を添加した材料においては添加量と燃焼抑制との間に比例関係が見いだされなかった. 熱重量分析とともに結果を整理し, 高分子の熱分解に視点をあてて解析を行った.

ジフェニルカーボネート (DPC) をモデル物質に用いてポリカーボネート (PC) の熱分解生成物の定量的解析を行った. 従来からPCの熱分解生成物の解析と分解経路については研究が行われているが, 一酸化炭素 (CO), 二酸化炭素 (CD) などの低沸点熱分解生成物については定量精度の問題などで明確ではなかった. しかし, COの生成は熱分解時の有毒ガス発生, CDの生成については燃焼性制御の場合の炭化層形成を考慮するのに重要な因子である. そこで本報では熱分解生成物の定量精度の向上と検定を目的として, DPCをモデル物質に用いて未分離ピークをマススペクトルで分離定量する方法と熱分解生成物の元素および構造比制約を考案し, それをPCの熱分解とその分解生成物の定量的解析に適用した. その結果, メタン, 水, CO, それにCDの定量精度が向上し, 元素および構造比制約で検定すると熱分解生成物の定量精度が高いことが明らかになった.

Parasporal inclusion proteins produced by Bacillus thuringiensis strain A1470 exhibit strong cytotoxicity against human leukemic T cells when activated by protease treatment. One of the cytotoxic proteins was separated by anion exchange chromatography and gel filtration chromatography and designated Cry45Aa. Its gene was then expressed in recombinant Escherichia coli, in which the Cry45Aa precursor was accumulated in an inclusion body. It was solubilized in sodium carbonate buffer and processed with proteinase K, and cytotoxic activities of the protein against various mammalian cell lines were evaluated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide assay. The protein exhibited high cytotoxic activity against CACO-2, Sawano, MOLT-4, TCS, and HL60 cells and moderate activity against U-937 DE-4, PC12, and HepG2 cells. On the other hand, the EC50 values against Jurkat, K562, HeLa, A549, Vero, COS-7, NIH3T3, CHO, and four normal tissue cells (human primary hepatocyte cells, UtSMC, MRC-5, and normal T cells) were >2 microg/mL.

We established an IgA monoclonal antibody (mAb) against Shiga toxin 1 B subunits (Stx1B) from mouse nasal-associated lymphoid tissues (NALT) of BALB/c mice. We have developed an improved protocol in which cross-linked Stx1B is intranasally administered together with cholera toxin. Surface IgA-positive NALT lymphocytes from mice immunized in this manner were enriched and then fused with mouse myeloma cells to produce hybridoma cells. Hybridoma culture supernatants were examined to see if they contain IgA against Stx1B and if they can inhibit carbohydrate recognition by Stx1B. For the latter purpose, we prepared carbohydrate ligands in which globotriose is present on the poly-lysine backbone. The established IgA mAb exhibited saturable and dose-dependent binding to the immobilized Stx1B. Inversely, the binding of the carbohydrate ligands to the immobilized Stx1B was inhibited by the mAb pretreatment. Immunoblotting and SDS-PAGE analysis revealed dimeric IgA. The IgA mAb inhibited the binding of digoxigenin-conjugated Stx1B to natural ligands displayed on a Burkitt's lymphoma cell line, Ramos. These results suggested that surface IgA-positive B cells in the inductive sites of the mucosal immune system in the upper respiratory tract are a potent source for producing IgA mAb against protein antigens with weak immunogenicity such as Stx1B.

The structural decay of wood (using “Obi” Japanese cedar) was studied by focusing on the effect of flame retardancy. The various flame retardants, including boron compound, used as one of the most popular flame retardants, were applied in this study. Thermogravimetric analysis, pyrolysis/gas chromatography/mass spectrometry, and elemental analysis were used to analyze the structural decay and thermal degradation. Flammability was observed via a vertical combustion test and a cone calorimeter. Woods to be alive was opened of pit for through the water. However, woods are independent and isolated each other by blockade of the pit at the end of their lives. Therefore, woods was prepared and destroy the pit under several conditions so as to be blended with flame retardants. After the flame retardants were impregnated, several thermal degradation tests were achieved. Boron showed an excellent effect on the flame retardancy and fluorocarbon acid salt and organic phosphate also showed a remarkable effect.

ポリカーボネート (PC) の加熱着火特性について試料形状を変化させ, ポリプロピレン (PP) と比較することによって解析を行った. 試料と加熱源との立体的位置関係は平面位 (加熱源が試料の平面の部分を照射する位置) と側面位 (同じく側面部分を照射する位置) で行った. また熱分解挙動, 定常燃焼の状態を測定し比較した. 基礎的知見を得るために行った実験では, 熱分解ではPCの方がPPより分解温度が高く, 定常燃焼ではPCの方が着火時間が長く, 燃焼の発熱量が小さく, 自己的に消炎するなど, 火災に対する安全性が高かった. 着火実験では, 試料厚さに関わらず着火時間の逆数は照射熱流束に比例し, 基本的な着火現象が加熱総熱量に依存することがわかった, またPC, PPにおいて試料厚さと着火に必要な加熱総熱量の関係は複雑な傾向を示し, 平面位, 側面位に対してそれぞれの特徴が見られた. 日本における火災による犠牲者は増加傾向にあり, 高分子材料の社会的課題として着火特性の重要性について示した.

The diffusion of additives and the deterioration with the passage of time in polypropylene (PP) were studied by using the UL flaming test and the oxygen index test to measure the flame retardancy. The weight change was also measured. The decreases with the lapse of time were observed for multiple flame retardants. Aliphatic brominated compounds showed the best result for flame retardancy in the initial stage of combustion. The best flame retardants for PP to inhibit the deterioration of flame retardancy with the passage of time were brominated hydrocarbon with more than two aromatic rings connected by a functional group or isocyanurate, and phosphates connected with a branching aliphatic hydrocarbon. The weight of the loss was plotted as a function of aging time and temperature to elucidate why the flame retardancy deteriorated. The apparent diffusion constant depends on the temperature and the rate was expressed with the Arrhenius equation. The concentration of flame retardant in PP was calculated by the constant and the equation at arbitrary time after thermal aging. The relation between the performance and chemical structure of the additives was also discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

ポリオキシメチレンは機械的性質などが優れたエンジニアリングプラスチックであるが工業的に優れた延伸フィルムは得られていない. 本研究では延伸フィルムの工業化を目的として逐次二軸延伸を試みた. 基礎実験で得られたプレス延伸と同時二軸延伸における結果を参考にして, 本研究では最初に圧延処理を行い, 続いて逐次二軸延伸を行った. 圧延処理では微細結晶が方向性をもち力学的特性に異方性が見られたが, ラメラ構造が微細化されることによって構造の安定性をもたらすことができることを明らかにした. 延伸行程では温度制御が重要であるが, 実験は主として170℃において延伸倍率8倍以上の条件で行った. 延伸倍率が10倍を超えると配向が強くなり逐次延伸が困難であった. 工業化を目指した延伸実験で得られたフィルムの引張弾性率は基礎試験で得られたものより低かったが, これは結晶成長速度と延伸時間の関係, および微結晶の配向の不均一さに由来すると考えられた. 本研究によって結晶構造を制御できればポリオキシメチレンの延伸フィルムを工業的に得ることが可能であることを明らかにした.

The effect of perfluoroalkane sulfonic acid on the flame retardancy of polycarbonate (PC) has been studied. In particular, the very small amount of additives to restrain the combustion, as well as the thermal degradation path, was focused on. The flaming combustion times of PC blended with 100 ppm of the strong acid salts by the Underwriter Laboratory (UL)‐test were less than 5 sec, which satisfied the V‐0 level of the UL‐94 test. The ignition times of the UL test did not change remarkably, but those observed in a cone calorimeter test clearly got shorter. Referring to the results of thermal and elemental analyses, the process by which PC was shown excellent flame retardancy is not dehydration and subsequent char‐formation, but includes different scission routes. In particular, the flame retardancy strongly depends on the scission of the isopropylidene group on the main chain.