Hot stage TEM investigations of dislocation climb in NiAl

Hot stage was used to investigate dislocation loop formation and growth at climb sources in Al rich alloys of β-NiAl. The loops grew by absorbing vacancies retained during cooling of the samples. The growth rate was dependent on the speed of cooling and anomalously high growth of loops occurred near the foil surfaces. The loop shapes were nearly square as a result of loop growth by a jog mechanism. Estimates of the vacancy concentration contained in the loops after growth demonstrated that nearly all thermal vacancies can be retained in NiAl.     

Hot stage TEM investigations of dislocation climb in NiAl

Hot stage was used to investigate dislocation loop formation and growth at climb sources in Al rich alloys of β-NiAl. The loops grew by absorbing vacancies retained during cooling of the samples. The growth rate was dependent on the speed of cooling and anomalously high growth of loops occurred near the foil surfaces. The loop shapes were nearly square as a result of loop growth by a jog mechanism. Estimates of the vacancy concentration contained in the loops after growth demonstrated that nearly all thermal vacancies can be retained in NiAl.     

提钒后钒钛磁铁精矿直接还原研究

首先运用Fact Sage软件从理论上分析了铁氧化物的还原反应在还原温度950~1 100℃下发生的可能性,然后将提钒后钒钛磁铁精矿与无烟煤按比例混匀、压样后进行直接还原实验,研究无烟煤添加量、原料粒度、还原温度、还原时间对还原产物金属化率的影响,并采用X射线衍射分析还原产物的物相变化.结果表明:在本论文还原温度下,还原反应在理论上是可以进行的.当无烟煤添加量(质量分数)为18%、原料粒度75μm、还原温度为1 100℃、还原时间为90 min时,还原产物的金属化率可达99.18%,还原产物的物相主要为金属铁、黑钛石以及硅酸盐.     

TEM investigations of the structural evolution in a pearlitic steel deformed by high-pressure torsion

A fully pearlitic steel was deformed by high-pressure torsion up to very high strains, and the changes in the microstructure were determined by analytic and conventional transmission electron microscopy. The imposed strain leads to a fragmentation and an alignment of the cementite lamellae parallel to the shear plane. The electron energy-loss near-edge-fine structures of the Fe-L_2,3-edge of the iron matrix and the cementite lamellae were measured with high spatial resolution. The results indicated that after high-pressure torsion, the iron matrix contains finely dispersed carbon-rich areas that do not show the electronic fingerprint of cementite. However, the refinement in microstructure leads to an enormous increase in mechanical strength.     

Neurogenesis in the adult human hippocampus

The genesis of new cells, including neurons, in the adult human brain has not yet been demonstrated. This study was undertaken to investigate whether neurogenesis occurs in the adult human brain, in regions previously identified as neurogenic in adult rodents and monkeys. Human brain tissue was obtained postmortem from patients who had been treated with the thymidine analog, bromodeoxyuridine (BrdU), that labels DNA during the S phase. Using immunofluorescent labeling for BrdU and for one of the neuronal markers, NeuN, calbindin or neuron specific enolase (NSE), we demonstrate that new neurons, as defined by these markers, are generated from dividing progenitor cells in the dentate gyrus of adult humans. Our results further indicate that the human hippocampus retains its ability to generate neurons throughout life.     

Inhibition of normal allogenic lymphocyte mitogenesis by a soluble inhibitor extracted from human colonic carcinoma

Soluble extracts from human colonic tumors (STE) and from their hepatic metastases (SHME) were found to be unable to induce a proliferative response among normal allogenic lymphocytes. However, addition of these tissue extracts to cultures stimulated with various mitogens resulted in an almost complete inhibition of lymphocyte DNA synthesis. Nevertheless, they did not reduce the unstimulated lymphocyte spontaneous proliferation. Control experiments have shown that normal or nonmalignant tissues do not affect the lymphocyte reactivity to mitogens. The specific immunosuppressive evvect was found to be irreversible and to block lymphocyte activation at an early stage. The inhibitor was soluble (not sedimented at 220,000 times G for 2 hr) and not nonspecifically cytotoxic. STE was slso found to induce morphologic alterations resulting in blastlike cell production. However, no mitotic figures were seen, even after colchicin treatment. It is suggested that STE might contain molecular component(s) which would exert a double effect: 1) trigger metabolic alterations responsible for the blast-like cell induction, and 2) inhibit the lymphoproliferative response. The significance of such a mechanism is discussed in conection with the nonspecific immunosuppression caused by a tumor and the immune unresponsiveness against the tumor itself. A preliminiary characterization of this tumor material has shown that its molecular weight was about 70,000 and that it is not related to carcinoembryonic antigen or alpha-fetoprotein.     

Typing of DNA HLA-DQ alpha alleles extracted from human nail material using polymerase chain reaction

The deoxyribonucleic acid (DNA) typing of human Leukocyte Antigen (HLA) DQ alpha from human fingernails is described. HLA-DQ alpha genotypes can be accurately determined from clipped fingernails. We have typed 26 nails accurately, while one did not give any type since that one sample did not amplify due to the low quantity of DNA. The cut off limit for the digested material to be amplified is approximately 9 mgs of nail material.     

Neural interaction in the human spiral ganglion: a TEM study

A TEM study was performed on freshly fixed human spiral ganglions (HSG) collected during skull base surgery. This technique gives well preserved tissue for ultrastructural analysis. Unlike spiral ganglion cells in mature animals so far studied, most HSG cells lack a myelin coat, but are surrounded by a thin rim of Schwann cell (SC) cytoplasm. In the region of maximal innervation density (upper basal and middle turn), HSG cells were frequently ensheathed by the same Schwann cell, forming a "unit-like" structure. In this region the cells often showed signs of physical interaction where the SCs were frequently incompletely developed ("gaps") so that the cell membranes of adjacent ganglion cells (sometimes as many as four in one section plane) were in direct apposition. In one thin section as many as 20 of 100 ganglion cells were found to face the cell membrane, at any point, of an adjacent cell. At these "gaps" in the SC, complexes of cell membrane specializations occurred between individual HSG cells. The same nerve junctions were also found between unmyelinated nerve fibres and the body of large ganglion cells. Our findings may challenge the view that afferent information in the acoustic nerve is conveyed uninterrupted to the CNS at the level of the spiral ganglion.     

从白云鄂博磁铁矿石中回收稀土的实践探讨

包钢选矿厂磁矿系列弱磁尾矿中稀土含量7.0%左右,改造前全部放尾.为了充分利用现有的原矿资源,拓宽生存空间,进行了在磁矿尾矿中选稀土的工业试验,取得了稀土浮选精矿RE0品位45.69%,相对原矿回收率28.87%,相对弱磁尾矿回收率32.24%的较好指标,标志着白云鄂博矿产资源综合利用工作又上了一个新台阶,开创了稀土选矿的新局面.     

Distribution of variables extracted from spectral EEG-analysis

9482 pregnant women searched for the Department of Prenatale Care of the town Karl-Marx-Stadt between 1968 and 1972. Obesity were found in 6, 2 p.c., glycosuria in 5, 1 p.c., a history of diabetes with glycosuria in 0,5 p.c. and obesity with gylcosuria in 0,5 p.c. The perinatale mortality rate was heightened only in the last group (3,7 p.c.) 51 prediabetic pregnant women were found in these five years by sugar screening. Eight women developed a White class A nad four women a White class B diabetes between 3 and 7 years later.     

Isolation of an HLA-A2.1 extracted human minor histocompatibility peptide

Purified HLA-A2.1 molecules obtained by affinity chromatography of 6 x 10(10) Epstein Barr virus (EBV)-transformed B lymphocytes were used in an attempt to isolate the human HLA-A2.1-restricted minor histocompatibility (H) peptides H-Y and HA-2. Fraction 18 of the high-performance liquid chromatography (HPLC)-separated HLA-A2.1 peptide pool was found to contain the natural HA-2 peptide. An HA-2-specific, HLA-A2.1-restricted cytotoxic T lymphocyte clone lysed HLA-A2.1+ HA-2- EBV-transformed B lymphocyte cell lines reproducibly and in a concentration-dependent fashion in the presence of fraction 18, but not in the presence of other HPLC fractions. By contrast, H-Y sensitizing activity was not found in any fraction. Amino acid sequencing of peptide fraction 18 revealed a mixture of peptides with maximal length of nine amino acids, in which the presence of Leu at positions 2 and 9 was dominant. Surprisingly, the HA-2 peptide could not be mimicked by any of the peptide mixtures synthesized according to the amino acid sequences found in fraction 18. Our failure to obtain the actual amino acid sequence of the human minor H peptide HA-2 from a peptide pool with the established pattern for binding to HLA-A2.1 may indicate that this CTL defined minor H peptide does not represent an abundant HLA-A2.1 binding peptide.     

Characterization of antichemotactic factor extracted from the gastric mucosa of rats

The gastric mucosa of normal rats exhibits no detectable inflammation or visible damage. We examined the effect of the gastric mucosal extract of rats on neutrophil chemotaxis and tried to purify antichemotactic factor. The chemotaxis of neutrophils was examined by the modified Boyden's method. After mucosal layer was scraped and then homogenized and centrifuged at 20,000 x g for 30 min, the supernatant was used as rat gastric mucosal extract (RGME). Prior exposure of neutrophils to the gastric mucosal extract caused a dose-dependent reduction in the neutrophil migration induced by formyl-methionyl-leucyl-phenylalanine (FMLP), leukotriene B4 (LTB4) and interleukin 8 (IL-8) without affecting the cell viability. The antichemotactic factor was partially purified by lectin affinity chromatography on wheat germ lectin (WGL)-Sepharose, anion exchange chromatography on Mono-Q and gel filtration on Superose 12. The molecular weight of the antichemotactic factor was estimated to be around 60 k by gel filtration. The activity was markedly abolished by boiling for 5 min, heating at 60 degrees C for 30 min, and treatment with 1% acetic acid, 0.1 M Na2CO3 or trypsin. Furthermore, the FMLP-induced migration of neutrophils pretreated with the antichemotactic factor for 5 min followed by washing with fresh medium was inhibited, although the factor was not added to the chamber. These results suggest that the gastric mucosa of rats intrinsically generates an antichemotactic factor which might play a crucial role in maintenance of the integrity of the gastric mucosa.     

Place cells, navigational accuracy, and the human hippocampus

The hippocampal formation in both rats and humans is involved in spatial navigation. In the rat, cells coding for places, directions, and speed of movement have been recorded from the hippocampus proper and/or the neighbouring subicular complex. Place fields of a group of the hippocampal pyramidal cells cover the surface of an environment but do not appear to do so in any systematic fashion. That is, there is no topographical relation between the anatomical location of the cells within the hippocampus and the place fields of these cells in an environment. Recent work shows that place cells are responding to the summation of two or more Gaussian curves, each of which is fixed at a given distance to two or more walls in the environment. The walls themselves are probably identified by their allocentric direction relative to the rat and this information may be provided by the head direction cells. The right human hippocampus retains its role in spatial mapping as demonstrated by its activation during accurate navigation in imagined and virtual reality environments. In addition, it may have taken on wider memory functions, perhaps by the incorporation of a linear time tag which allows for the storage of the times of visits to particular locations. This extended system would serve as the basis for a spatio-temporal event or episodic memory system.     

Study of glycoprotein extracted from synovial membranes of oxen

Authors describe a glycoprotein that they have extracted from synovial membrane of oxen. From a total extract CTC, the fraction is purified by precipitation with ethanol then by filtration on biogel. The composition and some physicochemical and immunogical characters are described.     

Contributions of the entorhinal cortex, amygdala and hippocampus to human memory

Recent studies have indicated that, in the monkey, the rhinal cortex (consisting of the entorhinal and perirhinal cortices) is more important to visual recognition memory than the hippocampus or amygdala. The present study investigated the role of the entorhinal cortex in humans using memory scores from surgical epilepsy patients classified according to their mesial temporal lobe pathology. The temporal lobe removals included 4-5 cm of neocortex, amygdala, rhinal cortex and 2-3 cm of the hippocampus and parahippocampal gyrus. Compared to autopsied control subjects, all of the patients showed significant gliosis in the amygdala, but they differed as to whether or not there were entorhinal and/or hippocampal abnormalities. Both preoperatively and one or more years postoperatively, the patients performed tests of verbal recall (Wechsler Memory Scale Logical Memory), visual recall (Rey Figure), verbal recognition and visual recognition (Warrington Recognition Memory Test: Words and Faces, respectively). Preoperatively, patients with hippocampal pathology showed deficits in visual recall. Postoperatively, a significant drop in verbal and visual recall was seen only for patients who lost intact hippocampal tissue, irrespective of the condition of the excised entorhinal cortex. Together, the results argue that the hippocampus is more important than the entorhinal cortex for the recall of newly learned information.     

钒钛磁铁矿提钒工艺发展历程及趋势

介绍了钒钛磁铁矿提钒工艺的发展历程及工艺现状,阐述了各种提钒工艺的优点、缺点、主要工艺参数和技术指标,针对现有提钒工艺的不足,指出了下一步提钒工艺的研究方向.     

Characterization of rabbit DNA microsatellites extracted from the EMBL nucleotide sequence database

Microsatellite polymorphisms are invaluable for mapping vertebrate genomes. In order to estimate the occurrence of microsatellites in the rabbit genome and to assess their feasibility as markers in rabbit genetics, a survey on the presence of all types of mononucleotide, dinucleotide, trinucleotide and tetranucleotide repeats, with a length of about 20 bp or more, was conducted by searching the published rabbit DNA sequences in the EMBL nucleotide database (version 323). A total of 181 rabbit microsatellites could be extracted from the present database. The estimated frequency of microsatellites in the rabbit genome was one microsatellite for every 2-3 kb of DNA. Dinucleotide repeats constituted the prevailing class of microsatellites, followed by trinucleotide, mononucleotide and tetranucleotide repeats, respectively. The average length of the microsatellites, as found in the database, was 26, 23, 23 and 22 bp for mono-, di-, tri- and tetranucleotide repeats, respectively. The most common repeat motif was AG, followed by A, AC, AGG and CCG. This group comprised about 70% of all extracted rabbit microsatellites. About 61% of the microsatellites were found in non-coding regions of genes, whereas 15% resided in (protein) coding regions. A significant fraction of rabbit microsatellites (about 22%) was found within interspersed repetitive DNA sequences.     

冀东磁铁精矿球团焙烧机理的研究

研究了焙烧温度、时间等因素对冀东磁铁精矿粉球团焙烧质量的影响.当预热温度超过1 000 ℃时,颗粒表面生成液相,造成球团氧化不完全;当焙烧温度超过1 275 ℃时,球团中的脉石大量同化,产生大量硅酸盐液相,降低成品球强度.冀东磁铁精矿球团最佳焙烧工艺为:氧化温度为900～950 ℃,氧化时间不低于20 min,焙烧温度为1 250～1 275 ℃,焙烧时间不低于20 min.     

Antigenic composition of protein fractions of the human cerebral cortex extracted by chromatography on DEAE-cellulose

In fractionating a phosphate protein extract from the human brain cortex on DEAE-cellulose 10 fractions of the basic acid proteins were received. Analyses of these fractions were conducted by the method of disc electrophoresis in polyacridamide gel with dodecylsulphate Na and a subsequent separate staining of the desitograms of proteins and glycoproteins, precipitation in agar gel, immunoelectrophoresis and autoimmunography with the use of labeled I125 antibodies to rabbit gamma-globulin. In the first 2 basic fractions there were brain specific antigens with electrophoretic mobility of the beta2--gamma globulin. In the first acid fraction--2 antigens: alpha1-globulin and alpha2-globulin of a glycoprotein nature. In subsequent acid fractions--one antigen with a mobility of alpha1-globulin. A study of the antigen activity of these fractions in a complement fixation test on cold with the serum of schizophrenic patients and disseminated sclerosis depicted differences in the activity of the basic and acid fractions.