建议尽早修订房屋建筑制图统一标准

ＧＢＪ１８６《房屋建筑制图统一标准》自１９８７年７月１日起实施以来,至今已经历了２０多年。在这段时间里,国家标准技术制图的陆续颁布以及计算机绘图的普及与发展,使得该标准有些内容已显得落后,并且在使用过程中,存在一些缺陷。本文提出尽早加以修订的建议,供有关人员参考。以下称ＧＢＪ１８６《房屋建筑制图统一标准》为“本标准”。一、根据国家标准《技术制图》来修订本标准《技术制图》是建筑、机械和船舶等工程制图所必须遵循的一项国家标准。自１９８９年起,至１９９６年《技术制图与机械制图》出版止,已先后颁布了…     

Specific racemization of heavy-chain cysteine-220 in the hinge region of immunoglobulin gamma 1 as a possible cause of degradation during storage

Therapeutic antibodies often suffer from degradation due to various modifications during storage. We detected a degradation of immunoglobulin gamma 1 (IgG1) stored for 6 month at 40 °C, and identified the modification as the racemization of Cys220 in the hinge sequence S(219)CDKTHT(225) of the heavy chain by tryptic peptide mapping and tandem mass spectrometry. The rate of racemization at Cys220 was enhanced deliberately by incubating the protein at 50 °C and pH 9.0, while all the other cysteine residues were not affected. The racemization of Cys220 was confirmed by mass spectrometry in conjunction with extracted ion chromatography of the tryptic digest of IgG1 forced to degrade in D(2)O and a series of synthetic hinge fragments containing D-amino acid, as well as the detection of D-cysteine in the acid hydrolysate. To rationalize the possible relationship between the racemization of Cys220 and isopeptide formation at the neighboring residue of Asp221, we suggest a new reaction mechanism that assumes a base catalyst to initiate these reactions by activating the amide nitrogen of Lys222. Due to the highly flexible nature of the hinge region, Lys222 can participate in either the formation of a cyclic imidazoline intermediate involving the α-carbonyl carbon of Cys220 to facilitate the racemization of Cys220 or that of a succinimide structure leading to the isomerization of Asp221.     

Enzyme-sharing as a cause of multi-stationarity in signalling systems

Multi-stationarity in biological systems is a mechanism of cellular decision-making. In particular, signalling pathways regulated by protein phosphorylation display features that facilitate a variety of responses to different biological inputs. The features that lead to multi-stationarity are of particular interest to determine, as well as the stability, properties of the steady states. In this paper, we determine conditions for the emergence of multi-stationarity in small motifs without feedback that repeatedly occur in signalling pathways. We derive an explicit mathematical relationship φ between the concentration of a chemical species at steady state and a conserved quantity of the system such as the total amount of substrate available. We show that φ determines the number of steady states and provides a necessary condition for a steady state to be stable—that is, to be biologically attainable. Further, we identify characteristics of the motifs that lead to multi-stationarity, and extend the view that multi-stationarity in signalling pathways arises from multi-site phosphorylation. Our approach relies on mass-action kinetics, and the conclusions are drawn in full generality without resorting to simulations or random generation of parameters. The approach is extensible to other systems.     

Further development of a model for rod ricochet

A ricochet model for long rods developed by the author has been revisited in search of solution efficiencies. By replacing a moment-of-momentum governing equation in the original model with a simpler minimization constraint, a solution technique has been developed that avoids the complexity of an iterative solution that characterized the original work. The revised model retains key elements of the original model, including: ricochet by way of plastic hinge formation; rod rebound from the target's ricochet surface; and target gouging as a means to redirect the target force's line of action. Finally, the ricochet equations are analytically rendered so as to give a keen sense of how the critical obliquity for ricochet varies as a function of the initial conditions of the ballistic engagement.     

Absenteeism as a major cause of bottlenecks in assembly lines

This paper analyses the effects of absenteeism in assembly lines. The analysis shows that assigning temporary workers as substitutes for absentees has a major potential for generating bottlenecks. Such a bottleneck typically appears when an inexperienced worker replaces an absentee worker at their position. The inexperienced worker starts their learning curve, and for the initial period is significantly slower than other stations, and therefore is a bottleneck. The paper analyses the effect of typical absenteeism rates on the throughput, and shows it has strategic magnitude. This is verified using simulation. The effect of the absenteeism and turnover on the throughput is found to be related to the cycle time, and the amount and rate of learning. The paper discusses the simulation results, staffing requirements, strategies for overcoming absenteeism, and future research directions.     

Dielectric resonator as a possible standard for characterization of high temperature superconducting films for microwave applications

The performance of several designs of dielectric resonators used for microwave characterization of FITS films has been analyzed from the point of view of accuracy, sensitivity, and range. Designs discussed include Hakki-Coieman shielded types as well as open-ended resonators with sapphire, rutile and (ZrSn)TiO₃ dielectrics. The best dielectric resonators have proved to have an uncertainty in surface resistance measurements only twice the uncertainty in theQ-factor. high sensitivity, and ability to measure a wide range of surface resistances. Hence the dielectric resonator technique can be considered as a standard for measurements of surface resistance of HTS films for wireless and PCS communication systems applications provided that adequate measurement procedures of theQ ₀-factor are followed.     

Biocompatibility of genipin-fixed porcine aorta as a possible esophageal prosthesis

In this study, porcine aortic tissues were fixed with genipin to construct an esophageal prosthesis. In vitro characterization was performed and in vivo biocompatibility experiments were undertaken to evaluate the biological properties of genipin-fixed porcine aortic tissues. The porcine aortic tissues fixed with genipin at pH 4.0, 0.625 g/100 ml initial fixative concentrations for 7 days showed more favorable characteristics. It was characterized by low antigenicity, good epithelial cellular compatibility, favorable biomechanical properties for an esophageal prosthesis, high resistance against enzymatic degradation and be readily available. The porcine aortic tissues fixed with genipin also showed good biocompatibility in vivo. The present study demonstrated that the genipin-fixed porcine aortic tissues could be a promising material for the construction of an esophageal prosthesis or fabricating scaffold for a tissue engineered esophagus.     

Distortion in a gradient-index rod

An algebraic formula is derived for the fifth-order distortion of a GRIN-rod lens. By measuring distortion, one can then determine the coefficients of the profile formula.     

Fracture analysis of a cutting tool used in a straightening and twin bended system for coiled re-bars machine

A company produces prefabricated stirrup cages for the reinforcement of concrete. The process consists of straightening, cutting and twin bending of coiled steel re-bars, in a custom produced machine. The punch of the cutting system failed repeatedly. Its cutting edges lose their functionality much earlier than expected. Two representative pieces were analyzed. The study included visual inspection, chemical analysis, hardness and micro-hardness measurements. Optical metallographic examination on representative samples was carried out. The fracture areas were analyzed using a scanning electron microscope (SEM) and the crack initiation and propagation were discussed. The punches failed by chipping wear mechanism due to low-cycle fatigue. Their repeating failures provoked by faulty machine design. Problem solving suggestions are proposed. In addition, alternatives related to material selection are provided in order to reduce crack susceptibility, in an economical way. Moreover, conclusions and recommendations can be useful, resulting in higher productivity of prefabricated stirrup cages.     

Ectopic mediastinal parathyroid carcinoma as a cause of dialysis-dependent renal failure

Carcinoma of the parathyroid gland is infrequent in patients with secondary hyperparathyroidism. Typical clinical symptoms are related to the presence of a neck mass and hypercalcemia. We describe a case of a 55-year-old man in whom primary parathyroid carcinoma led most likely to the development of end-stage dialysis-dependent renal failure, and the diagnosis of the cancer was delayed due to ectopic localization of the tumor, and dramatic complications in the clinical course of the disease, including acute pancreatitis and peritionitis. However, 6 months after successful surgery and subsequent radiotherapy, the patient is well and free from recurrences but remains chronically dialysis-dependent.     

A model for rod ricochet

A model to predict the ballistic ricochet of rod penetrators is presented. The model is based on the premise that the phenomenology of ricochet is one where the impacting rod feeds into a plastic hinge located at the rod/target interface, and is thus diverted from a penetrating trajectory. The model is offered in both a full and simple form. The full form of the model arises from the simultaneous solution of a series of six algebraic equations that constitute the momentum-flux/force and moment balances upon the plastic hinge, subject to various material and kinematic constraints. This full model is not solvable in closed form, but rather by way of algorithm. The simple form of the model, by contrast, dispenses with the moment balance and makes several simplifying kinematic assumptions that permit the ricochet criterion to be expressed as a closed-form inequality. Such a simplified form is along the lines of, and thus directly comparable to, several prior ricochet models in the literature. Compared against 24 ballistic tests, comprising two separate ricochet studies, the current model (in both forms) shows an improved ability to predict the ballistic ricochet of impacting rod projectiles. The simple form of the current ricochet model actually proved the best predictor of the ballistic data.     

Nonstationary heating of a conical rod

The Galerkin-Kantorovich method is used to obtain an approximate solution of the nonstationary problem of heat conduction for a thin conical rod.     

Elastic-plastic torsion of a Cosserat-type rod

Summary Elastic-plastic torsion of a Cosserat-type rod of a solid circular cross-section is considered. The governing equations are linearised using a small parameter which is equal to the relative grain rize. The linearized problem is subjected to asymptotic analysis based on the singular perturbation technique. Qualitative features of the elastic-plastic state of the rod are discussed. Apparently, this is the first explicit asymptotic solution for the elastic-plastic Cosserat continuum.     

CDW as a possible reason for the pseudogap in the normal state of high-T c cuprates

Two possible reasons for an instability with wave vector Q = (/gp,π) near the half-filling have been studied. The superexchange coupling of copper spins yields of-wave symmetry of the pseudogap. Nevertheless, the calculated critical temperature,T*, in this case is almost two times smaller than that observed experimentally in the bilayered cuprates. The phonon-mediated interaction (CDW scenario) provides the correct order of magnitude ofT*. As the symmetries of the pseudogaps differ in both cases, T* does not increase when we switch them on simultaneously.     

Some elements for a revision of the americium reference biokinetic model

The interpretation of individual activity measurement after a contamination by 241Am or its parent nuclide 241Pu is based on the reference americium (Am) biokinetic model published by the International Commission on Radiological Protection in 1993 [International Commission on Radiological Protection. Age-dependent doses to members of the public from intake of radionuclides: Part 2 Ingestion dose coefficients. ICRP Publication 67. Ann. ICRP 23(3/4) (1993)]. The authors analysed the new data about Am biokinetics reported afterwards to propose an update of the current model. The most interesting results, from the United States Transuranium and Uranium Registries post-mortem measurement database [Filipy, R. E. and Russel, J. J. The United States Transuranium and Uranium Registries as sources for actinide dosimetry and bioeffects. Radiat. Prot. Dosim. 105(1-4), 185-187 (2003)] and the long-term follow-up of cases of inhalation intake [Malátová, I., Foltánová, S., Becková, V., Filgas, R., Pospísilová, H. and H?lgye, Z. Assessment of occupational doses from internal contamination with 241Am. Radiat. Prot. Dosim. 105(1-4), 325-328 (2003)], seemed to show that the current model underestimates the retention in the massive soft tissues and overestimates the retention in the skeleton and the late urinary excretion. However, a critical review of the data demonstrated that all were not equally reliable and suggested that only a slight revision of the model, possibly involving a change in the balance of activity between massive soft tissues, cortical and trabecular bone surfaces, may be required.