Three-dimensional morphology and bony range of movement in hip joints in patients with hip dysplasia

To confirm whether developmental dysplasia of the hip has a risk of hip impingement, we analysed maximum ranges of movement to the point of bony impingement, and impingement location using three-dimensional (3D) surface models of the pelvis and femur in combination with 3D morphology of the hip joint using computer-assisted methods. Results of computed tomography were examined for 52 hip joints with DDH and 73 normal healthy hip joints. DDH shows larger maximum extension (p = 0.001) and internal rotation at 90° flexion (p < 0.001). Similar maximum flexion (p = 0.835) and external rotation (p = 0.713) were observed between groups, while high rates of extra-articular impingement were noticed in these directions in DDH (p < 0.001). Smaller cranial acetabular anteversion (p = 0.048), centre-edge angles (p < 0.001), a circumferentially shallower acetabulum, larger femoral neck anteversion (p < 0.001), and larger alpha angle were identified in DDH. Risk of anterior impingement in retroverted DDH hips is similar to that in retroverted normal hips in excessive adduction but minimal in less adduction. These findings might be borne in mind when considering the possibility of extra-articular posterior impingement in DDH being a source of pain, particularly for patients with a highly anteverted femoral neck.

Effects of Janus kinase inhibitor tofacitinib on circulating serum amyloid A and interleukin-6 during treatment for rheumatoid arthritis

The Janus kinase inhibitor tofacitinib is currently being investigated as a disease-modifying agent in rheumatoid arthritis (RA). We investigated the in-vivo effects of tofacitinib treatment for 4 weeks on elevated circulating acute-phase serum amyloid (SAA) levels in 14 Japanese patients with RA. SAA levels fell from 110·5 ± 118·5 μg/ml (mean ± standard deviation) at treatment initiation to 15·3 ± 13·3 μg/ml after 4 weeks treatment with tofacitinib. The reduction in SAA levels was greater in patients receiving tofacitinib plus methotrexate compared with those receiving tofacitinib monotherapy. Tofacitinib was also associated with reduced serum interleukin (IL)-6, but had no effect on serum levels of soluble IL-6 receptor. Patients were divided into groups with adequate (normalization) and inadequate SAA responses (without normalization). Serum IL-6 levels were reduced more in the group with adequate SAA response compared with those with inadequate SAA response. These results suggest that tofacitinib down-regulates the proinflammatory cytokine, IL-6, accompanied by reduced serum SAA levels in patients with active RA. The ability to regulate elevated serum IL-6 and SAA levels may explain the anti-inflammatory activity of tofacitinib.

U-shape rotating anti-cathode compact X-ray generator: 20 times stronger than the commercially available X-ray source

A new type of U-shape anti-cathode X-ray generator in which the inner surface of a cylindrical target is irradiated by an electron beam has been made by modifying a conventional rotating anti-cathode X-ray generator whose brightness in the catalog is 12 kW mm(-2). The target material (Cu), target radius (50 mm) and rotating speed (6,000 r.p.m.) were not changed in this modification. A brightness of 52 kW mm(-2) was obtained by this U-shape-type X-ray generator. This means that the brightness of the new type is 4.3 times greater than that of the old unmodified one. Furthermore, the new-type X-ray generator yielded a brightness of 129 kW mm(-2) by adding a carbon coating on the Cu target. This means an overall increase of brightness of ten times. The original generator has the highest brightness in the generators of the same class (having a radius of 50 mm and rotation speed of 6,000 r.p.m.). Observations showed that Cu Kα counts at vertical incidence of the electron beam onto the surface of the new target, which is initially optically smooth, decrease as the surface is roughened by a severe thermal stress caused by strong electron beam exposure. Further observation reveals, however, that oblique incidence of the electron beam onto the roughened surface drastically increased the X-ray output and amounts to twice as much as that from a smooth surface at vertical incidence. Thus, at the present stage, an overall increase of brightness has been realised at a level 20 times stronger than that of the original commercially offered X-ray generator that we modified.

Differences in the locations and modes of labral tearing between dysplastic hips and those with femoroacetabular impingement

We investigated differences in the location and mode of labral tears between dysplastic hips and hips with femoroacetabular impingement (FAI). We also investigated the relationship between labral tear and adjacent cartilage damage. We retrospectively studied 72 symptomatic hips (in 68 patients: 19 men and 49 women) with radiological evidence of dysplasia or FAI on high-resolution CT arthrography. The incidence and location of labral tears and modes of tear associated with the base of the labrum (Mode 1) or body of the labrum (Mode 2) were compared among FAI, mildly dysplastic and severely dysplastic hips. The locations predominantly involved with labral tears were different in FAI and mild dysplastic hips (anterior and anterosuperior zones) and in severely dysplastic hips (anterosuperior and superior zones) around the acetabulum. Significant differences were observed in the prevalence of Mode 1 versus Mode 2 tears in FAI hips (72% (n = 13) vs 28% (n = 5)) and severe dysplastic hips (25% (n = 2) vs 75% (n = 6)). The frequency of cartilage damage adjacent to Mode 1 tears was significantly higher (42% (n = 14)) than that adjacent to Mode 2 tears (14% (n = 3)).

Hip pathology is significantly related to the locations and modes of labral tears. Mode 1 tears may be a risk factor for the development of adjacent acetabular cartilage damage.

Cite this article: Bone Joint J 2013;95-B:1320–5.

Swallowing frequency in elderly people during daily life

Disuse atrophy of swallowing-related organs due to an excessive decrease in swallowing frequency is suspected to occur in patients with poor oral intake, especially elderly people. However, swallowing frequency in daily life has not previously been examined in the elderly. This study examined swallowing frequency in elderly people and compared these findings to those in a younger population and differences in the degree of activity in daily life. (i) We compared swallowing frequency in 20 elderly people (82·0 ± 8·3 year) and 15 healthy young people (26·5 ± 3·5 year). (ii) 20 elderly people were divided into two groups according to the degree of activity in daily life: a semi-bedridden group and bedridden group; the swallowing frequency was compared between these groups. (i) The swallowing frequency in the elderly people was 2-19 times per hour and the mean was 9·4 ± 4·9, and that in the healthy young people was 16-76 times per hour and the mean was 40·7 ± 19·5. Swallowing frequency in elderly people was significantly lower than that in young healthy people (P < 0·0001). (ii) The swallowing frequency in bedridden group was 2-11 times per hour and the mean was 6·8 ± 3·3, and that in semi-bedridden group was 3-19 times per hour and the mean was 11·9 ± 5·1. Swallowing frequency in bedridden group was significantly lower than that in semi-bedridden group (P < 0·05). These results indicate that in daily life, elderly people tend to swallow less frequently than young people. In addition, swallowing frequency was lower in elderly subjects with a low degree of activity in daily life.

Development of a Direct Polycondensation Process for Poly (L-lactic acid)

Poly(L-lactic acid) (PLLA) is quite promising for use as biodegradable and non-petroleum derived plastics. In this study we developed an innovative two-step polycondensation process so as to produce economically PLLA with high molecular weight. The process is composed of both melt polycondensation under the lactide-re ux and solid-phase polycondensation. First we studied a direct polycondensation of L-lactic acid with a small amount of solvent, using a mixture of L-lactic acid as raw material, diphenyl ether as solvent, Tin (II) chloride dihydrate as catalyst, and p-toluene sulfonic acid as a discoloration prevention agent. After the dehydrative oligomerization of L-lactic acid, the polycondensation of the oligocondensates and solid-phase post-polycondensation, PLLA of Mw = 266,000 could be obtained. Then, we carried out direct bulk polycondensation tests from L-lactic acid without any solvent added. After optimization of the reaction conditions, PLLA with Mw = 134,000 was successfully produced by the melt-poly-condensation of L-lactic acid accompanied by solid-phase post-poly-condensation. In both systems, the lactide-re ux was indispensable for promoting dehydration/water removal. The re uent lactide was taken into the polymer-chain by trans-esterification reaction during the melt-poly-condesation. Furthermore, the catalyst was allowed to deactivate and stabilize during the solid-phase polymerization to cause the Mw growth.

Polymer Processing Technology in the 21st Century from the Viewpoint of the Japanese Plastics Industry

Recent progress in polymerization easily allows the control of precise structure of a base polymer and accelerates lower-cost production using larger-scale-plants. In addition to this, today's more important issue in our industry is the development of the key-technology corresponding to a sustainable society. Under these circumstances, the polymer industry in Japan has been focussing on down-stream products from upper-stream using advanced processing technology. To meet today's trends, the polymer industry should establish more sophisticated technology in both higher functionality and hybridization to survive in the 21st century. In particular, various hybridized polymer-processing systems such as the combination of reactive extrusion and injection molding should be applied to create cost-effectiveness and less environmental burdens as well as higher performance.

Pumping Characteristics of an Intermeshing Co-rotating Twin Screw Extruder

The pumping characteristics of several types of screw elements for an intermeshing co-rotating twin screw extruder (ICoTSE) were experimentally studied using molten polystyrene (PS) as a typical non-Newtonian fluid in “LABOTEX30α”. Here, the throughput was regarded as the remainder of drag flow minus pressure flow, based on the previous theoretical and experimental studies with regard to either single or twin-screw extruders. Therefore, the relationship between the throughput and the pressure gradient for a given screw geometry was approximately expressed as a linear dimensionless relation containing two so-called pumping-characteristic parameters which depend on the element geometry and degree of departure of the used fluid from the Newtonian fluid.

The pumping-characteristic parameters for two right-hand flighted screw elements (RF) with leads of 0.938D and 0.703D, a neutral kneading disk (NK) and a blister ring (BR) were experimentally determined, and the RF with a lead of 0.938D was taken as an example to observe the effect of the clearance between it and the barrel wall on its pumping-characteristic. The results show that the linear relationship between the dimensionless throughput and the dimensionless pressure gradient for each type of the screw elements used here is a good approximation, and the clearance in the range used here greatly affects the pumping characteristic of the RF.

Moreover, the degree of filling and the pressure profile in two kinds of screw configurations used for water-injection foaming devolatilization, which consist of elements with different diameters but with the same dimensionless geometry as those used in this work, were predicted and discussed by using the determined pumping-characteristic parameters under the conditions of given throughput of molten PS and screw speed.

Biodegradable Poly(Lactic Acid) with High Molecular Weight

Biodegradable plastics have been quickly accepted as one of the key solutions for today's waste plastics problems in Japan. Particularly, poly(lactic acid) is looked forward to as the most promising biodegradable plastics because of its high quality in optical and physical properties as well as chemical recyclability and compostability. Furthermore, lactic acid as a raw material of this polymer can be produced from agricultural starch wastes. However, one of the greatest issues in biodegradable plastics including poly(lactic acid) and lactic acid-based copolymers lays in their extremely high price when compared to typical commodity plastics on the market. Regarding poly(lactic acid), a polymer with high molecular weight of more than Mw = 100 000 is conventionally obtained only by a ring-opening polymerization process from lactide, i.e., dimer of lactic acid, which is very expensive.

To aim at developing practical and economical technologies for effectively producing poly(L-lactic acid) as a representative of lactic acid-based polymer, we have been carrying out continuous melt-polymerization experiments using the combination of a batch type stirred reactor and an intermeshed twin screw extruder in this study. As a result, we have successfully obtained poly(L-lactic acid) with higher molecular weight of up to Mw = 150 000 from lactic acid by a continuous melt-polycondensation process.

Modeling of Polymer Devolatilization in a Multi-vent Screw Extruder

A model for representing polymer devolatilization behavior in a screw extruder with multi-vent sections has been proposed. In this model, an overall film-interface geometry factor (OFIGF) comprised of several local film-interface geometry factors (LFIGF) is used as a measure for the devolatilizing performance of a screw extruder. Moreover, the OFIGF is related to screw geometries and open angles of open areas in vent sections, and dependent on the degree of filling or the flowrate of the fluid and the screw speed. An intermeshing co-rotation twin-screw extruder popularly used was taken as an example to discuss the effect of the OFIGF on its devolatilizing performance. For this purpose, a solution of how to calculate the local film-interface areas and their exposure time in a venthole unfitted zone (VUfZ) and a venthole fitted zone (VFZ) with an open area was presented. Furthermore, several interesting results about how the OFIGF is affected by flowrate, screw speed, lead, and number of tips were predicted and discussed. The results suggested that the devolatilizing performance of the VFZ is lower than that of the VUfZ due to decrease in the surface renewal effect there, and a plot of ln {(wout – w*)/(win – w*)} against (N1/2/Q) in generally used flowrate and screw speed ranges for a given screw geometry does not strictly satisfy a linear relationship due to the filling-degree dependence of the OFIGF.

Influence of Melting Zone and Melt Homogeneity on Extrusion and Injection Molding Processes

In this study, the melting behavior and melt homogeneity in a single screw extruder have been investigated to obtain better products in quality and higher productivity for extrusion and injection molding. For the analysis of the melting behavior, so-called “cooling experiments” were used. For the melt homogeneity evaluation, furthermore, molten polymer temperature fluctuations at the exit of a single extruder and injection molding machine were measured. As a result of these analyses, we have concluded that the melting process in extrusion and injection molding played an important role on improving product quality and its productivity. Based on experiments and analyses on the melting mechanism, we have developed a mixing and kneading screw configuration with a new melting process, in which the compulsory circulation flow in solid bed accelerates rapid melting of raw materials and melt homogeneity.

Plastics Magnet Manufacturing Process: Mixing, Kneading, and Injection Molding

To manufacture anisotropic plastic magnets with higher magnetic power, the compounding of Strontium Ferrite powder / plastics binder and injection molding processes should be optimized. In this study, we have carried out the optimization of injection molding machine design, and the mechanism analysis of the compounding operation. As a result, to generate effective strong magnetic fields during injection molding, the coiling system, mold structure, and pole shape were very important elements. Better Ferrite powder dispersion accelerated the particle orientation, which lead to higher magnetic power of the molded product when strong magnetic fields were applied. And then, particle dispersion depended on specific energy of the compounding machine unless excessive shearing force degraded Ferrite and plastics binder.

Experimental Study on Dewatering and Devolatilizing Operations Using Intermeshed Twin Screw Extruders

In this study, we have mainly discussed the dewatering and devolatilizing extrusion behavior of synthetic elastomers using intermeshed twin screw extruders. For these purposes, we utilized various twin screw extruders with long segmented barrels having several slitted sections and venting ports. Furthermore, we selected the optimum operational conditions using either the intermeshed co- or counter-rotation twin screw extruder depending on experimental purposes and raw materials. Some results obtained were compared between the co- and counter-rotation twin screw extruder.

Process for Improvement in Toughness of Unsaturated Polyester with Elastomer

By combined usage of a high speed intermeshing twin screw extruder and an injection molding press, a direct reactive extrusion and injection molding process has been developed for improving toughness of the thermoset unsaturated polyester (UP) by blending with an elastomer.

The unsaturated polyester and elastomer were homogenously kneaded with each other and a radical initiator dissolved in a liquid monomer was added to the molten mixture. This was carried out at a relatively low temperature from the final feeding port of the twin screw extruder to allow not the curing reaction to proceed during the twin screw extrusion stage.

The molten UP-elastomer alloy was accumulated, injected into the hot mold, and cured. The products obtained from these experiments were evaluated with regards to their physical properties and their morphologies. The elastomer, NBR produced the greatest improvement in toughness. The physical properties of the UP-NBR alloy obtained by this reactive extrusion process were generally equivalent to those of polypropylene except for thermal characteristics.