A study of FMS part type selection approaches for short-term production planning

This research compares seven approaches from the literature to the selection of part types for simultaneous production over the next time horizon. A flexible approach to the selection of part types and the simultaneous determination of their mix ratios so as to balance aggregate machine workloads is presented. Constraints on tool magazine capacity are considered. Simulation studies are conducted on realistic, detailed models of flexible flow systems (FFSs) configured as pooled machines of equal sizes. The simulated settings are constructed to evaluate the impact of such factors as blocking, transportation, buffer utilizations, and fixture requirements and limitations of various types. One of the goals of this study is to encourage industry to relax, for those FMS types for which the procedure is appropriate, what is essentially an artificial constraint: that tool changing be isolated in time, to a period between batches. For other types of FMSs, batching may be appropriate. The results indicate that using the flexible approach enables the system to be more highly utilized. It is also observed that the batching approaches tend to require more fixtures of each type than the flexible approach. The system utilizations for the batching approaches seem to be more sensitive to restrictions on the number of fixtures of each type. Further research needs are also discussed.     

Sodium-dependent lysine flux across bullfrog alveolar epithelium

Amino acid transport across the alveolar epithelial barrier was studied by measuring radiolabeled lysine fluxes across bullfrog lungs in an Ussing chamber. In the absence of a transmural electrical gradient, L-[14C]lysine was instilled into the upstream reservoir and the rate of appearance of the radiolabel in the downstream reservoir was determined. Two lungs from the same animal were used simultaneously to determine tracer fluxes both into and out of the alveolar bath. Results showed that the radiolabel flux measured in the alveolar to the pleural direction was greater than that measured in the opposite direction in the presence of sodium in the bathing fluids. The net flux of L-[14C]lysine was saturable with [Na+], with an apparent transport coefficient (Kt) of 28 mM for Na+. Hill analysis of [14C]lysine flux vs. [Na+] indicated a coupling ratio of 1:1 between sodium and radiolabeled L-lysine. Total L-lysine flux as a function of [L-lysine] was also saturable, with Kt of 7.3 mM for L-lysine. Ouabain significantly decreased absorptive (alveolar-to-pleural) radiolabel flux, while slightly increasing the flux observed in the opposite direction. L-leucine completely inhibited absorptive net flux of L-[14C]lysine. alpha-Methylaminoisobutyric acid (MeAIB), on the other hand, only slightly reduced net flux of L-[14C]lysine from the control value. The presence of a net absorptive, Na+-dependent amino acid flux across the alveolar epithelial barrier indicates that the tissue is capable of removing amino acids and sodium from the alveolar fluid by a coupled cotransport mechanism, which may be important for both protein metabolism and fluid balance by alveolar epithelium.     

泡状饶氏藻营养细胞的超微结构研究

本文报道我国特有的一种绿藻门植物－泡状饶氏藻营养细胞的超微结构特征,植物体由3层细胞组成,外层细胞最小,细胞质比较丰富,含有较多的各种细胞器,液泡体积较小,中层细胞具有很大的中央液泡,细胞质成为贴壁的薄层,各种细胞器结构仍清晰可见,内层细胞极度液泡化,细胞质呈现退化状态,周生的片状叶绿体上有许多大小不等的穿孔,使叶绿体呈网孔状外貌,叶绿体主要由许多成对的类囊体组成,叶绿体上往往有几个蛋白核,蛋白核经常被1或2条类囊体穿过,呈现分隔状,本文也报道了泡状饶氏藻的线粒体,质体,内质网,高尔基体和核内微管的结构特征,根据泡状饶氏藻的类囊体形态与Ulva mutabilis非常相似以及蛋白核的超微结构特征,它与石莼科植物可能有较密切的亲缘关系,属于绿藻门中进化的类群。     

Further study of effects of synthetic peptides on identifiable giant neurones of an African giant snail (Achatina fulica Férussac)

1. Effects of the following peptides at 10(-4) M on identifiable giant neurones of Achatina fulica Férussac were examined: physalaemin, eledoisin, bradykinin, neurokinin A, neurokinin B, neuromedin B, gastrin releasing peptide decapeptide (neuromedin C), gastrin releasing peptide (14-27), cholecystokinin tetrapeptide, cholecystokinin octapeptide, thyrotropin releasing hormone, Arg-vasotocin, gamma-melanocyte stimulating hormone. 2. The six neurones tested were as follows: PON (periodically oscillating neurone), TAN (tonically autoactive neurone), RAPN (right anterior pallial neurone), d-RPLN (dorsal-right parietal large neurone), VIN (visceral intermittently firing neurone) and d-VLN (dorsal-visceral large neurone). 3. Of the peptides examined, only Arg-vasotocin at 10(-4) M produced the excitatory effects on PON, VIN and d-VLN. Physalaemin showed slight inhibitory effects on TAN; this substance was sometimes almost ineffective on the neurone. 4. The other peptides examined were completely ineffective on all of the neurones tested.     

Divergent changes in the concentrations of gonadotropin beta-subunit messenger ribonucleic acid during the estrous cycle of sheep

Cyclic changes in the production of the pituitary gonadotrophic hormones, LH and FSH are essential events in the maintenance of the reproductive system of female mammals. While studies have examined changes in the secretion of LH and FSH during the estrous cycle and demonstrated the importance of these hormones in regulation of ovarian development and gametogenesis, considerably less is known concerning the regulation of the biosynthesis of these hormones. Although initial studies have examined changes in LH subunit mRNA concentrations during the rat and ovine estrous cycles, no information concerning the physiological regulation of FSH beta mRNA concentrations has been available. In the present study we have examined the relationship between pituitary concentrations of LH and FSH subunit mRNAs and the serum concentrations of these gonadotropins. The results demonstrate a very different pattern of change for FSH beta subunit mRNA than that observed for alpha and LH beta subunit mRNAs. In fact, FSH beta mRNA concentration decline substantially during the preovulatory period, reaching minimal values at a time when alpha and LH beta mRNA levels are near maximal. Furthermore, this decline in FSH beta mRNA amounts occurs when serum FSH concentrations are maximal. Thus, FSH beta mRNA concentrations follow a very different pattern than that of serum FSH. In contrast, LH beta mRNA and serum LH concentrations tend to increase at the same time. These findings provide evidence that concentrations of LH beta and FSH beta mRNAs are likely regulated by different mechanisms.     

Development of shoot inHydrangea macrophylla I. Terminal and axillary buds

The structure of shoots, in particular of winter buds, ofHydrangea macrophylla was examined. The non-flower-bearing shoot is usually composed of a lower and an upper part, between which a boundary is discernible by means of a distinctly short internode. This internode is the lowermost of the upper part, and it is usually shorter than the internodes immediately above and below, although the internodes tend to shorten successively from the proximal to the distal part of the shoot. Variations exist in the following characters among the terminal bud, the axillary bud on the lower part of the shoot and the axillary bud on the upper part: (1) length of bud; (2) character of the outermost pair of leaf primordia; (3) degree of development of secondary buds in the winter bud; and (4) the number of leaf primordia. Usually, the terminal bud contains several pairs of foliage leaf primordia with a primordial inflorescence at the terminal of the bud, but the axiallary bud contains only the primordia of foliage leaves in addition to a pair of bud scales.     

Cardiac transplantation in severely ill patients requiring intensive support in hospital

Sixty four patients were referred for cardiac transplantation from a single cardiac team at this hospital between October 1984 and December 1986. Of these patients, 33 were referred for urgent transplantation, all of whom required intensive treatment in hospital with intravenous infusions of cardiac drugs, intra-aortic balloon counterpulsation, peritoneal dialysis, ventilation, or any combination of these to sustain life. Of these 33 patients, six died while awaiting transplantation, one was removed from the waiting list for a transplant, and 26 received cardiac transplants. There were five deaths within 24 hours of operation and one death 10 days after the operation. Twenty of those who had surgery had a successful outcome of transplantation, but there was one late death 10 weeks postoperatively and a further death 31 months after surgery. Eighteen patients were alive and well 10 to 33 months (mean 19·4 months) after transplantation, with an overall survival rate after surgery of 69%.Provided that surgery can be performed before renal failure has progressed such that renal transplantation is necessary, the results are excellent (surgical survival 85·5%) and, we believe, justify the expenditure and staffing requirements necessary to treat these terminally ill patients.     

用体外免疫法建立人—人抗流行性乙型脑炎病毒杂交瘤细胞株

利用单克隆抗体(McAb)进行病毒病的治疗是人们所关心的一个重大课题。 流行性乙型脑炎(乙脑)是一种严重威胁人民健康的急性传染病,病死率高,后遗症严重。国内外目前尚无特效疗法。陈伯权等用乙脑病毒皮下或腹腔感染3周龄小白鼠24、48小时及5天后,分别用乙脑病毒51-8McAb进行治疗,平均治愈率分别为78％、73％及22％。     

小鼠Lewis肺癌组织中层粘连蛋白受体的分离及其性质的研究

层粘连蛋白(Laminin,LN)是基膜(basement membrane)中的一种主要大分子糖蛋白。一些研究资料表明肿瘤细胞的浸润转移可能与LN有关。肿瘤细胞与LN的作用可能是通过细胞表面LN受体进行的。本文采用亲和层析法从小鼠Lewis肺癌组织中分离LN受体并对其理化性质进行研究。Lewis肺癌LN受体的表观分子量为70,000,还原后SDS电泳图为一条较宽的条带。氨基酸组成中疏水氨基酸占38％,苏氨酸、絲氨酸、门冬氨酸(包括门冬酰胺)占23.5％,通过硝酸纤维素膜片法用HRP-LN测定受体与LN的结合特性,证明具有配基结合专一性,饱和性及高亲和性(Kd=0.95×10~(-9)mol/L)。     

The purified yeast pre-mRNA splicing factor PRP2 is an RNA-dependent NTPase.

Unlike autocatalyzed self-splicing reactions, nuclear pre-mRNA splicing requires transacting macromolecules and ATP. A protein encoded by the PRP2 gene of Saccharomyces cerevisiae is required, in conjunction with ATP, for the first cleavage-ligation reaction of pre-mRNA splicing. In this study, we have purified two forms of the PRP2 gene product with apparent molecular weights of 100 kDa and 92 kDa, from a yeast strain overproducing the protein. Both proteins were indistinguishable in their ability to complement extracts derived from a heat-sensitive prp2 mutant. Furthermore, we show that the PRP2 protein is capable of hydrolyzing nucleoside triphosphates in the presence of single-stranded RNAs such as poly(U). However, purified PRP2 by itself did not unwind double-stranded RNA substrates. The fact that an RNA-dependent NTPase activity is intrinsic to PRP2 may account for the ATP requirement in the first catalytic reaction of pre-mRNA splicing.