Vibration reduction during milling of highly flexible workpieces using active workpiece holder system

The milling of highly flexible workpieces, such as thin-walled structures used in turbine blades, aerospace equipment, and jet engine compressors, requires vibration compensation to improve the quality of the workpiece surface. Vibration can be reduced by selecting appropriate cutting parameters. However, this approach reduces system productivity. This paper presents an active workpiece holder that controls the vibration of general computer numerical control machine tools. The proposed holder, which comprises a flexible guide mechanism, driver, and sensor, measures vibration and actively controls it using piezoactuators. A high-rigidity flexure mechanism was designed for the holder, and finite element method simulation and modal analysis were performed. Finally, the proposed system was fabricated, and experimental verification indicated that the system reduced vibration. The surface quality obtained using the controlled system was ∼50% better than that obtained using the uncontrolled system.

Single-port laparoscopy-assisted donor right hepatectomy in living donor liver transplantation: sensible approach or unnecessary hindrance?

BACKGROUND

Single-port laparoscopic (SPL) surgery has rapidly gained attention worldwide. Since May 2008, we have propagated the use of SPL surgery, mainly for cholecystectomy and appendectomy. Recently, we have used this modality of minimally invasive surgery for various liver surgeries. We hereby discuss our outcomes of SPL-assisted donor right hepatectomies.

METHODS

The preoperative workup is the same as for a standard donor hepatectomy. We retrospectively reviewed the data of 150 patients who underwent donor right hepatectomy from October 2008 to May 2011. We divided them into 3 groups depending on the type of surgical procedure.

RESULTS

Among 150 patients, 20 underwent laparoscopy-assisted donor right hepatectomy (LADRH); 40 underwent single-port laparoscopy-assisted donor right hepatectomy (SPLADRH); and 90 underwent open donor right hepatectomy (ODRH). The donor demographics were comparable among the groups. Postoperative complication and reoperation rates revealed no significant differences. The SPLADRH group showed the lowest level of postoperative pain, thereby leading to a better quality of life postoperatively.

CONCLUSIONS

SPLADRH seems to be a simple, feasible approach.

Undiagnosed urethral carcinoma: an unusual cause of female urinary retention

Female urinary retention is extremely rare. Two cases of female urethral carcinoma that presented as urinary retention are reviewed and discussed.

Production and characterization of monoclonal antibodies against alpha and beta spectrin subunits

Twenty monoclonal antibodies against human erythrocyte spectrin were generated using purified native spectrin as the immunogen. Thirteen out of 20 monoclonal antibodies reacted to the alpha subunit, and the remaining seven monoclonal antibodies reacted to the beta subunit in Western blot analysis. One anti-beta subunit and two anti-alpha subunit monoclonal antibodies cross-reacted with the cell lysate of the non-erythroid T. lymphoma, J. Jhan, cell line. Identification of 20 monoclonal antibodies to the respective tryptic domains was also achieved. The specificity of these antibodies to respective tryptic domains of spectrin confirms the alignments and uniqueness of each of the previously identified five domains in the alpha subunit and four domains in the beta subunit, and establishes the identity of proteolytic daughter peptide fragments.

Characterization and nucleotide sequences of the variable regions of a monoclonal antibody against alpha-fetoprotein

alpha-Fetoprotein (AFP) is a well-known tumor marker of hepatocellular carcinoma (HCC). Monoclonal antibodies against AFP possessing specific binding ability to HCC are potential candidates for immunoscintigraphy and immunotherapy. A new monoclonal antibody against AFP (0325-6-9) was isolated. Its specificity and targeting tumor ability were characterized by enzyme-linked immunosorbent assay (ELISA), cell immunostain and complement killing. These results suggest that 0325-6-9 is specific to hepatoma cells. The nucleotide sequences of variable regions of 0325-6-9 were determined by M13 dideoxynucleotide sequencing method. With the information of nucleotide sequence, this antibody then could be modified by recombinant technology for its usage in in vivo diagnosis and immunotherapy.

Purification of radioiodinated human insulin by high performance liquid chromatography for a sensitive radioimmunoassay

The optimal sensitivity of a radioimmunoassay depends on the purity of the radiolabeled antigen. The conventional purification methods are not complete and are time consuming. The combination of a Sep-pak C18 cartridge and high performance liquid chromatography (HPLC) for the purification of 125I-labeled insulin in our study revealed that the Sep-pak cartridge can serve as the preliminary step to remove unreacted radioactive iodide, the reactants, and labeled but presumably damaged materials unadsorbed to the cartridge. The fractions eluted from the Sep-pak containing high radioactivity and high immunoreactivity to the antibody were chosen for further purification by HPLC to eliminate undesirable radiolabeled substances with a lesser immunoreactivity. The purified radiolabeled insulin was used to develop a sensitive radioimmunoassay with detecting limits of 0.03 microU/mL per tube.

Preparation of radioiodinated secretin for radioimmunoassay

Radioiodination of synthetic human secretin on its N-terminal histidyl residue was not difficult when a greater amount of Chloramine T and a longer reaction time were employed to achieve better incorporation of 125I. The radioiodinated tracer for an optimal radioimmunoassay required purification. The combination of Sep-pak C18 Cartridge and high performance liquid chromatography for the purification of 125I-secretin in our study revealed that the Sep-pak cartridge was a preliminary step in removing unlabeled radioactive iodide, the reactant, and labeled materials unadsorbed to the cartridge. The eluate eluted from the Sep-pak containing high radioactivity and high immunoreactivity to the antibody were selected for further purification by HPLC which eliminated undesirable radiolabeled substances with lower immunoreactivity. The purified radiolabeled secretin was used in developing a sensitive radioimmunoassay.

The production of polyclonal and monoclonal antibodies in mice using novel immunization methods

Two novel immunization methods (intrasplenic and intra-inguinal lymph node) have been developed for the production of polyclonal and monoclonal antibodies in mice. Freund's complete adjuvant and antigen were mixed in the ratio of 1:2 (v/v). Various concentrations of human serum albumin (HSA) were used as antigen. No primary immune response was induced with 0.1 microgram of HSA in either of the methods studied. Intrasplenic immunization resulted in the strongest primary immune responses using all other doses of HSA. The primary immune response induced by intrasplenic immunization with 0.5 microgram of HSA was higher than any response induced by subcutaneous immunization with various doses of HSA. Inguinal lymph node immunization was less effective than intrasplenic immunization but better than subcutaneous immunization with 1-50 micrograms of HSA. Comparisons were also made of the efficacy of different adjuvants when inducing primary immune responses with 1 microgram of HSA. Freund's complete adjuvant resulted in a much stronger response than Freund's incomplete adjuvant and alum. Both intrasplenic and inguinal lymph node immunization using 1-5 micrograms of HSA were able to induce strong primary immune responses. Secondary immunization with either method or intravenous injection 3 days before fusion resulted in a higher frequency of specific monoclonal antibodies.

Chloroplast and nuclear genomes of Chlamydomonas reinhardtii share homology with Escherichia coli genes for DNA replication, repair and transcription

Most of the cpDNA genes studied to date are genes encoding elements of the photosynthetic apparatus and translational machinery. Much less is known about genes encoding the polypeptides involved in transcription, cpDNA replication, recombination and repair. The similarities between bacterial and some cpDNA genes were exploited to identify some of these chloroplast genes using bacterial probes. Probes derived from the Escherichia coli genes dnaA, recA, uvrC, transcriptional factor rho, and rpoC were used to search for homologous DNA sequences in chloroplast and nuclear genomes of Chlamydomonas reinhardtii. Regions homologous to all of these genes were located on the cpDNA physical map by probing restriction fragments of cpDNA with plasmid fragments containing these genes. Probing nuclear DNA with bacterial gene probes revealed DNA fragments homologous to dnaA and rpoC genes.

Transcription and translation of mitochondrial DNA in interspecific somatic cell hybrids

We examined the mitochondrial transcription and translation products of somatic cell hybrids constructed by the fusion of Chinese hamster and mouse cells. The hybrid cell lines OAC-k, OAC-l, and OAC-m contain approximately equal amounts of hamster and mouse mitochondrial DNA and produced mitochondrial rRNA from both parental species in the same ratio. Cell lines OAC-k, OAC-l, and OAC-m also produced poly(A)+ mouse mitochondrial RNA transcripts comparable in complexity and quantity to poly(A)+ RNA from the mouse parent. However, the overall level of poly(A)+ hamster mitochondrial RNA from these hybrids was significantly reduced compared with that from the hamster parent. The hybrid cells also lacked several poly(A)+ RNA species found in the hamster parent, but contained additional minor transcripts. The mitochondrially coded proteins of the OAC-k, OAC-l, and OAC-m cells were predominantly encoded by the mouse mitochondrial DNA.

Describing a Robot's Workspace Using a Sequence of Views from a Moving Camera

This correspondence describes a method of building and maintaining a spatial respresentation for the workspace of a robot, using a sensor that moves about in the world. From the known camera position at which an image is obtained, and two-dimensional silhouettes of the image, a series of cones is projected to describe the possible positions of the objects in the space. When an object is seen from several viewpoints, the intersections of the cones constrain the position and size of the object. After several views have been processed, the representation of the object begins to resemble its true shape. At all times, the spatial representation contains the best guess at the true situation in the world with uncertainties in position and shape explicitly represented. An octree is used as the data structure for the representation. It not only provides a relatively compact representation, but also allows fast access to information and enables large parts of the workspace to be ignored. The purpose of constructing this representation is not so much to recognize objects as to describe the volumes in the workspace that are occupied and those that are empty. This enables trajectory planning to be carried out, and also provides a means of spatially indexing objects without needing to represent the objects at an extremely fine resolution. The spatial representation is one part of a more complex representation of the workspace used by the sensory system of a robot manipulator in understanding its environment.

Extracting compact objects using linked pyramids

This correspondence describes a method of extracting compact regions from images using three multiresolution (``pyramid'') representations of image features. The method makes use of a gray-level pyramid in which linking of similar nodes at successive levels smooths the image into uniform regions; an edge pyramid in which linking of similarly oriented edge elements serves to delineate the boundaries of the detected regions; and a ``surroundedness'' pyramid in which pixels surrounded by edges are detected.

Compact region extraction using weighted pixel linking in a pyramid

This correspondence describes a method of image segmentation based on a ``pyramid'' of reduced-resolution versions of the image. It defines link strengths between pixels at adjacent levels of the pyramid, based on proximity and similarity, and iteratively recomputes the pixel values and adjusts the link strengths. After a few iterations, the strengths stabilize, and the links that remain strong define subtrees of the pyramid; the leaves of each tree are the pixels belonging to a compact (piece of a) homogeneous region in the image.

Purification of Drosophila acidic ribosomal proteins

The relatively acidic proteins (group A80) of Drosophila melanogaster ribosomes were separated by ion-exchange chromatography. Fractions containing one or more acidic proteins were combined into thirteen pools. The criterion for the combination was the migration pattern in one-dimensional polyacrylamide gels containing sodium dodecyl sulphate. Five proteins (7/8, S25/S27, S14, L1/L2 and L5/L6) required no further purification. The others were further purified as follows: proteins S7, and S9 by preparative gel electrophoresis: and protein 13 (to newly identified protein) by adsorption with conconavalin-A--agarose. Four proteins had no detectable contamination, and in each of the others the impurities were no greater than 3%. The amount of purified protein recovered from a starting amount of 2.63 g total 80-S ribosomal protein and a starting amount of 105 mg group A80 varied from 0.4 mg to 8.8 mg. The molecular weight of the proteins was estimated by polyacrylamide gel electrophoresis in sodium dodecyl sulphate. The amino acid composition of the individual purified proteins was determined. Several phosphorylated proteins were identified. Proteins 13b and 13c are phosphorylated derivatives of 13a; 7b/8b and 7c/8c are phosphorylated derivatives of 7a and/or 8a. Proteins 7/8 and 13 are distinct proteins but are very similar in amino acid composition.

Threshold selection using quadtrees

A simple class of piecewise constant approximations to an image is constructed as follows: start with the entire image, subdivide it into quadrants if its gray level standard deviation is high, and repeat the process for each quadrant. This yields a decomposition of the image into blocks, each having low standard deviation, so that each of them can be approximated by a constant value, namely, its mean. The histogram of this approximated image tends to have sharper peaks than that of the original image since the block averaging reduces the variability of the gray levels within homogeneous regions. A possible way of further improving the histogram is based on the fact that small blocks tend to occur near region borders; thus, suppressing these blocks should tend to deepen the valleys on the histogram, making threshold selection (to separate regions of different types) easier. Conversely, the histogram of the small blocks only represents a population of pixels near region borders, and if there are only two types of regions (e.g., objects and background), the mean of this histogram should be a useful threshold for separating them; but in practice, this method is not very reliable since background fluctuations also give rise to border pixels.