化学有序及磁有序在铁基合金相平衡影响方面的交互作用

It is well known that the magnetic properties such as the Curie temperature TmagC and the mean magnetic moment β of ordered compounds have different values from those of the disordered solutions. For instance, both Tcmag and β of the Ni3 Pt (L12) and NiPt (L10) and Tcmag of the CoPt (L10) and CoPt3 (L12) ordered compounds are strongly depressed due to the ordering compared with those of the metastable disordered Ni-Pt and Co-Pt alloys. On the other hand, the γ-FeNi3(L12) and the α-FeCo (B2) ordered compounds have higher Tcmag and β values comparing with the disordered solution phases, γ (A1) and α (A2), respectively. In consequence, the stability of the ordered phase is depressed or enhanced due to the interaction between the chemical and magnetic ordering caused by the decrease or increase of Tcmag and β values. The purpose of this study is to investigate the effect of the interaction between the chemical and the magnetic ordering on the phase equilibria in the Fe-X(X=Al, Co, Ni, Rh, Si) binary systems.The Gibbs energy of the α(A2), γ(A1) and liquid phases is described by a sub-regular solution approximatior. The ordering contribution to the Gibbs energy ,ΔGmorder, and deviations of magnetic properties, ΔTcmag and Δβ, of the ordered compounds, FeAl(B2), Fe3 Al (D03), FeCo (B2), FeRh (B2), FeSi (B2), Fe3 Si (D03) and FeNi3 (L12) is introduced by the split compound energy formalism. Effect of the interaction between the chemical ordering, B2, D03 and L12 and the magnetic ordering on the phase equilibria will be discussed according to the calculated phase diagrams of the Fe-X binary systems.     

Co-Al二元系中的fcc/hcp马氏体相变和形状记忆效应

It is known that pure Co undergoes martensitic transformation from γ phase (fcc) to ε phase (hcp) by the movement of a/6<112> Shockley partial dislocations at around 400 ℃, however, there have been few systematic works on the SM effect in Co and Co-based alloys. In this study, the fcc/hcp martensitic transformation and the SM effect were investigated in Co-Al binary alloys(mole fraction of Al=0～16%).The γ/ε martensitic transformation temperatures were found from the DSC measurements to decrease with increasing Al content, while the transformation temperature hystereses were observed to increase from 60 ℃ at x(Al)=0 to 150 ℃at x(Al)= 16%. The SM effect evaluated by a conventional bending test was enhanced by the addition of Al over 4%(mole fraction) and Co-Al alloys containing over 10%(mole fraction) exhibit a good SM effect associated with the hcp →fcc reverse transformation above 200 ℃. The SM effect was significantly improved by precipitation ofβ (B2) phase and the maximal shape recovery strain of 2. 2% was obtained, which can be explained by precipitation hardening. The crystallographic orientations between theβ, ε and γ phases were also determined. Finally, the magnetic properties were investigated and it was found that the Curie temperature and saturation magnetization of Co-14% Al(mole fraction) are 690 ℃and 120 emu/g, respectively. It is concluded that the Co-Al alloys hold promise as new high-temperature and ferromagnetic SM alloys.     

Neoadjuvant concurrent chemoradiotherapy followed by definitive high-dose radiotherapy or surgery for operable thoracic esophageal carcinoma

PURPOSE: A prospective clinical trial was undertaken to investigate the feasibility of concurrent chemoradiotherapy for esophageal carcinomas. MATERIALS AND METHODS: Between June 1989 and May 1996, forty patients with operable squamous cell carcinoma of the thoracic esophagus (Stage 0 to III: UICC 1987), ages 45 to 78 years (mean: 64), were enrolled in a study of neoadjuvant concurrent chemoradiotherapy followed by definitive high-dose radiotherapy (CRT group) or surgery (CRT-S group). Neoadjuvant chemoradiotherapy consisted of 44 Gy in 40 fractions for 4 weeks (2.2 Gy/2 Fr/day) through 10-MVX rays, with 2 courses of cisplatin (80-100 mg/body, mean: 60 mg/m2, Day 1, bolus injection) and 5-fluorouracil (500-1000 mg/body/day, mean: 400 mg/m2, Days 1-4, continuous infusion). After completion of neoadjuvant chemoradiotherapy, an intermediate clinical response was assessed by barium swallow, esophagoscopy with/without biopsy, EUS in most cases, thoracic and upper abdominal CT scan, and cervical US. Definitive chemoradiotherapy was performed in patients when regression of more than 75% was evident (CRT Group), and esophageal resection was indicated in those who remained at less than 75% (CRT-S Group). In CRT Group, a cumulative dose of 60-70 Gy for Tis, T1 and 65-75 Gy for T2-T4 tumor with high-dose-rate intraluminal brachytherapy and a total of 3 courses of chemotherapy were planned. In CRT-S Group, intraoperative radiotherapy for abdominal lymphatic system and postoperative supraclavicular irradiation were added. RESULTS: At the time of intermediate assessment, complete response (CR) was observed in 16 patients, a partial response (PR) in 22, and no change (NC) in 2. Thirty responding patients (CR, 16; PR, 14) entered the CRT Group, and 10 nonresponding patients (PR, 8; NC, 2) were followed by surgery (CRT-S Group). Radiotherapy was completed satisfactorily, but chemotherapy was suspended in 26 patients (65%) because of acute toxicity. Clinical CR rate at the completion of treatment showed 90% in CRT Group, and pathologic CR rate 10% in CRT-S Group. The overall median survival was 45 months, survival at 1, 2, and 3 years being 100%, 72%, and 56%, respectively. Local-regional failure was observed in 7 patients (all in CRT Group), distant failure in 6 (3 in CRT Group, 3 in CRT-S Group) and local-regional with distant failure in 1 (CRT Group). Four patients with local-regional recurrence in the CRT Group were salvaged by surgery. Overall survival at 2 and 3 years for CRT vs. CRT-S Group was 72%, 64% vs. 75%, 38%, respectively. No treatment-related mortality was observed. The rate of the 'esophagus conservation' was 65% (Stage 0: 1 of 1, 100%; Stage I: 11 of 12, 92%; Stage II: 8 of 17, 47%; Stage III: 6 of 10, 60%). CONCLUSION: Our results demonstrated that almost all early disease (Stage 0-I) and about half of advanced disease (Stage II-III) could be conserved, their esophagus treated by the multidisciplinary approach centering on high-dose radiotherapy and concurrent chemotherapy.     

Characterization of [3H]clozapine binding sites in rat brain

We examined the characteristics of [3H]clozapine binding sites in four rat brain regions (frontal cortex, limbic area, hippocampus and striatum) in order to elucidate the pharmacological profile of this unique atypical antipsychotic drug. The specific [3H]clozapine binding was found to be saturable and reversible in all these brain regions. Scatchard analysis of the saturation data indicated that the specific binding consisted of high- and low-affinity components. Displacement experiments showed that the muscarinic cholinergic receptor represented about 50% of [3H]clozapine binding in each brain area. Serotonin 5-HT2 and dopamine D4 receptor binding sites could also be detected by displacement experiments using ketanserin and nemonapride, respectively, in frontal cortex and limbic area, but not in hippocampus or striatum. Alpha-1, alpha-2, histamine H1, dopamine D1, D2, or D3 receptor components could not be determined within the high-affinity [3H]clozapine binding sites in any brain region. It is possible that the atypical property of clozapine may depend on the modulatory effect on dopaminergic function via 5-HT2 receptor blockade and/or may be mediated via D4 receptor blockade in the mesocortical and mesolimbic area.     

Site-directed mutagenesis of the putative active site residues of 3C proteinase of coxsackievirus B3: evidence of a functional relationship with trypsin-like serine proteinases

Picornavirus 3C proteinases (3C^pro) are cysteine proteinasesbut recent sequence analyses have shown that they are relatedto trypsin-like serine proteinases. Two models of 3C^pro structurehave been presented. Both models indicate that residues His40and Cysl47 are members of the catalytic triad but the modelsdiffer in the designation of the third member of the catalytictriad, which is assigned as either Glu71 or Asp85. To test theimportance of these four residues in the catalytic activityof 3C^pro of coxsackievirus B3, a member of the enterovirus subgroupof the picornavirus family, single amino acid substitutionswere introduced at each of the four sites. All of these mutationsresulted in the reduction or inactivation of autocatalytic cleavageof the 3C precursor protein expressed in Escherichia coli, suggestingthat all of these residues are essential for the proteolyticreaction. The substitution of Cysl47 with Ala abolished 3C^proactivity while the mutant in which Cysl47 was replaced withSer retained reduced proteolytic activity both in cis and intrans. Our results strongly support the proposal that Cysl47of 3C^pro functions as a nucleophile analogous to Serl95 of trypsin-likeserine proteinases.     

醋酸菌对C57BL/6J小鼠的酒精性肝损伤的影响研究

该文针对摄入醋酸菌对于酒精性肝损伤的影响进行了评价。将C57BL/6J小鼠（8周龄,雄性,22～27 g）分为对照组（非乙醇给药组）、乙醇组（给予2.5 g/kg乙醇）、乙醇+醋酸菌组（给予2.5 g/kg乙醇+10 mg醋酸菌）,分别每天给药3次,连续经口给药14 d,测定了血清谷草转氨酶（AST）、谷丙转氨酶（ALT）及肝脏油脂浓度。结果表明,与对照组相比较,乙醇组小鼠的AST与ALT浓度,肝脏甘油三酯与胆固醇浓度显著增高（P＜0.05）;乙醇+醋酸菌组的数值则显著低于乙醇组（P＜0.05）。以上结果表明,摄入醋酸菌有可能会减轻酒精性肝损伤。     

Differential release of smooth-type lipopolysaccharide from Pseudomonas aeruginosa treated with carbapenem antibiotics and its relation to production of tumor necrosis factor alpha and nitric oxide

Endotoxin release from Pseudomonas aeruginosa treated with cell wall-active carbapenem antibiotics and its effect on the production of tumor necrosis factor alpha and nitric oxide were examined. Treatment of bacteria with imipenem induced much lower levels of endotoxin release than treatment with meropenem. The endotoxin released was demonstrated to be of the smooth type and O-specific polysaccharide-rich. The exposure of the filtrates of P. aeruginosa treated with imipenem to physiologically relevant cells caused low-level production of tumor necrosis factor alpha and nitric oxide, while similar treatment with meropenem induced high levels of production.     

Study of static cushioning properties and construction of a database for static cushioning properties

The rapid advance of computerization in industrial package design has led to a strong tendency toward CAD/CAM systems using personal computers for quick design and trial manufacturing. New tools based on a database of the cushioning properties of packaging materials will be needed for the design of package cushioning. Using a compression testing machine with computer control, an attempt has been made to construct such a database with registered characteristics for 47 samples of foamed polyethylene, foamed polypropylene and foamed polyethylene-polystyrene. This database offers the following functions and is recorded on floppy disk: (i) calculation of static cushioning properties (value); (ii) print-out of the computed results; (iii) drawing characteristic figures for designing package cushioning; (iv) indicating optimum value of static cushioning properties; (v) additional registration of new samples.     

Cytoplasmic regulation of the movement of E-cadherin on the free cell surface as studied by optical tweezers and single particle tracking: corralling and tethering by the membrane skeleton

The translational movement of E-cadherin, a calcium-dependent cell-cell adhesion molecule in the plasma membrane in epithelial cells, and the mechanism of its regulation were studied using single particle tracking (SPT) and optical tweezers (OT). The wild type (Wild) and three types of artificial cytoplasmic mutants of E-cadherin were expressed in L-cells, and their movements were compared. Two mutants were E-cadherins that had deletions in the COOH terminus and lost the catenin-binding site(s) in the COOH terminus, with remaining 116 and 21 amino acids in the cytoplasmic domain (versus 152 amino acids for Wild); these are called Catenin-minus and Short-tailed in this paper, respectively. The third mutant, called Fusion, is a fusion protein between E-cadherin without the catenin-binding site and alpha-catenin without its NH2-terminal half. These cadherins were labeled with 40-nm phi colloidal gold or 210-nm phi latex particles via a monoclonal antibody to the extracellular domain of E-cadherin for SPT or OT experiments, respectively. E-cadherin on the dorsal cell surface (outside the cell-cell contact region) was investigated. Catenin-minus and Short-tailed could be dragged an average of 1.1 and 1.8 micron by OT (trapping force of 0.8 pN), and exhibited average microscopic diffusion coefficients (Dmicro) of 1.2 x 10(-10) and 2.1 x 10(-10) cm2/s, respectively. Approximately 40% of Wild, Catenin-minus, and Short-tailed exhibited confined-type diffusion. The confinement area was 0.13 micron2 for Wild and Catenin-minus, while that for Short-tailed was greater by a factor of four. In contrast, Fusion could be dragged an average of only 140 nm by OT. Average Dmicro for Fusion measured by SPT was small (0.2 x 10(-10) cm2/s). These results suggest that Fusion was bound to the cytoskeleton. Wild consists of two populations; about half behaves like Catenin- minus, and the other half behaves like Fusion. It is concluded that the movements of the wild-type E-cadherin in the plasma membrane are regulated via the cytoplasmic domain by (a) tethering to actin filaments through catenin(s) (like Fusion) and (b) a corralling effect of the network of the membrane skeleton (like Catenin-minus). The effective spring constants of the membrane skeleton that contribute to the tethering and corralling effects as measured by the dragging experiments were 30 and 5 pN/micron, respectively, indicating a difference in the skeletal structures that produce these two effects.     

Fabrication of periodical nanostructures using electron interference fringes

A scanning interference electron microscope (SIEM) has been developed for periodical nanostructure fabrication. This system can produce electron interference fringes with a period from 2 nm to several ten microns. Fabrications of periodical nanostructures with 23 to 170 nm period have been demonstrated by transferring electron interference fringe onto semiconductor surfaces.