Chemical Cross-Linking of Anatase Nanoparticle Thin Films for Enhanced Mechanical Properties.

Titania nanoparticle-based thin films are highly attractive for a vast range of commercial applications. Although their application on polymer-based substrates is particularly appealing, the requirement of low process temperatures results in low mechanical stability. Highly crystalline anatase nanoparticles were used as the building blocks for coatings through a two-stage process. The main benefits of this method, over the more common sol-gel ones, are the relatively low temperature required for the production of metal oxide coatings, allowing the use of polymer-based substrates, and the defined crystallinity of the resulting thin films. Although in several cases moderate temperatures can be utilized for drying the films, the mechanical stability of the respective coatings remains a critical issue. In this contribution, we present a strategy to achieve network formation between TiO2 nanoparticles in a preformed thin film on the basis of the cross-linking of the functionalized nanoparticles. In the first stage, the nanoparticles were functionalized by dicarboxylic acids, concurrently leading to a stable colloidal dispersion that could be utilized for dip-coating to obtain TiO2 thin films with high homogeneity and optical transparence. During the second stage, the films were immersed in a solution of a diamine as the linker molecule, to achieve cross-linking between the nanoparticles within the film. It is demonstrated that indeed covalent bonding was realized and functional coatings with significantly enhanced mechanical properties were obtained by our strategy.

PARAMIS parallel robot for laparoscopic surgery.

The paper presents the parallel robot, which has been developed in Romania and it is used for laparoscope camera positioning. Based on its mathematical modeling, the first low-cost experimental model of the PARAMIS surgical robot has been built. The system has been built in such a way that it has the possibility to transform it in a multiarm robot controlled from the console. The control input allows the user to give commands in a large area for the positioning of the laparoscope using different interfaces: joystick, microphone, keyboard & mouse and haptic device. The first results have been obtained through the performing of an experimental laparoscopic cholecystectomy using PARAMIS surgical robot. The model which was used was a porcine liver, removed with the gall-bladder and the bile ducts. Due to its very easy use control system, surgeons have adapted rapidly to the use of PARAMIS in surgical procedures. Some of its advantages could be emphasized: precision of the movements; absence of the laparoscope operator's natural tremor, direct control over a smooth, precise, stable view of the internal surgical field for the surgeon; no fatigue; allows the use of both hands for the actual procedure; reduces eye fatigue; eliminates the need for a second surgeon to be present for the entire procedure.

[Pro- and supination impairments due to torsional deformities of the radial diaphysis before and after ulna osteotomy]. / Pro- und Supinationseinschränkungen bei Torsionsfehlstellungen der Radiusdiaphyse vor und nach Ulnaosteotomie.

The aim of this experimental study was to measure the exact influence of torsional deformities at the middle third of the radial shaft before and after osteotomy of the ulnar shaft on the rotation of the forearm. Intact and fresh cadaver specimens were fixed in a newly developed apparatus that allowed free pronation and supination. A ring fixator was applied to the radial shaft with K wires that allowed torsional deformities to be stabilized in steps of 10 degrees. The middle of the radial shaft was osteotomized via a small soft tissue window leaving the other soft tissues including the interosseous membrane intact. Supination and pronation were measured using a goniometer in a standardized fashion. The mean supination value before osteotomy of the radius was 71.6 degrees [standard deviation (SD)15.2 degrees], the mean pronation value was 64.5 degrees (SD 12.4 degrees). Radial osteotomy caused no significant difference in the range of motion prior to creation of torsional deformities. Supination torsional deformities greater than 30 degrees showed a significant loss of pronation and pronation torsional deformities greater than 30 degrees resulted in a significant loss of supination in 14 fresh cadavers, respectively. The amount of mean rotational loss was approximately the same in the respective pronation and supination torsional deformities. In the next step the influence of an ulna osteotomy on the range of motion was evaluated in different torsional deformities. In the four cadavers measured, there was an increase of the range of motion in the direction of the torsional deformity. These values were not significant when compared to values before ulna osteotomy, but there were significant changes to the non deformity (p=0.004 for pronation, p=0.003 for supination). Impairment of range of motion in the opposite direction of the deformity showed a similar appearance as values before ulna osteotomy. Again, there were significant changes to the non deformity (p=0.003 for pronation, p=0.005 for supination).

Kinematics of the ulna during pronation and supination in a cadaver study: implications for elbow arthroplasty.

OBJECTIVE: Aim of this study was to exactly describe and quantify kinematics of the ulna during pro- and supination. DESIGN: Biomechanical study in fresh frozen cadavers. BACKGROUND: A previous MRI study revealed a varus/valgus motion of the ulna averaging 7.1 degrees during pro-/supination. Axial rotation, however, could not be quantified. METHODS: Sixteen arms were examined in a new apparatus that fixed the humerus on a template and allowed forearm rotation. Motion of a Kirschner wire placed in the ulna was recorded in steps of 30 degrees by two perpendicularly arranged charge coupled device cameras during pro- and supination. RESULTS: From supination to pronation the ulna showed a semi-lunar evasive motion in the coronal and transverse plane with an initial varus shift, then a dorsal and finally a valgus shift. Motion in the coronal plane averaged 14.14 degrees (SD 4.78). Valgus angles of the ulna in 30 degrees, 60 degrees and 90 degrees pronation were significant (P<0.05) to each other and the neutral position. Varus angles of the ulna in 30 degrees, 60 degrees and 90 degrees supination (P<0.01) were significant to each other and the neutral position.A maximum ulnar axial pronation rotation of 3.2 degrees (SD 2 degrees ) was noted. Axial rotation angles of 90 degrees and 60 degrees of pronation were significant to each other and to the neutral position (P<0.05), respectively. CONCLUSIONS: To prevent increased stress on the bone-cement interface in elbow arthroplasty, a mean axial rotation of at least 3.2 degrees should be possible.

Computer simulation of forearm rotation in angular deformities: a new therapeutic approach.

A new computer-assisted simulation of forearm rotation based on orthogonal radiographs of the forearm is introduced. A new computer program called STOOPS was developed based on a new kinematic model describing motion of the radius and ulna in regards to forearm rotation. The computer program allows simulation of angular deformities of the forearm and can predict subsequent rotational impairment. To validate the program, the authors compared the actual pronation of 21 patients with angular deformities with the predicted pronation by STOOPS. The mean difference between the simulated and clinically measured pronation was 5.6 degrees (S.D. 9.4 degrees ). There was no statistically significant difference between the measured and simulated values. Using the computer-assisted simulation may help predict impairment of pronation due to angular deformities. If clinical impairment differs from the computed one, other causes such as lesions to the interosseous membrane or the adjacent joints have to be excluded. If values are similar, correction of the angular deformities should result in improvement of forearm pronation.

A new kinematic model of pro- and supination of the human forearm.

We introduce a new kinematic model describing the motion of the human forearm bones, ulna and radius, during forearm rotation. During this motion between the two forearm extrem-positions, referred to as supination (palm up) and pronation (palm down), effects occur, that cannot be explained by the the established kinematic model of R. Fick from 1904. Especially, the motion of the ulna is not properly reproduced by Fick's model. During forearm rotation an evasive motion of the ulna is observed by various authors, using magnetic resonance imaging MRI) technology. Our new kinematic model also simulates this evasive motion. Furthermore, the model is enlarged to include angulations of the forearm bones. Using these results the influence of forearm fractures on the range of forearm motion can be predicted. This knowledge can be used by surgeons to choose the optimal therapy in re-establishing free forearm mobility.

Marker enrichment and high-resolution map of the segment of potato chromosome VII harbouring the nematode resistance gene Gro1.

The dominant allele Gro1 confers on potato resistance to the root cyst nematode Globodera rostochiensis. The Gro1 locus has been mapped to chromosome VII on the genetic map of potato, using RFLP markers. This makes possible the cloning of Gro1 based on its map position. As part of this strategy we have constructed a high-resolution genetic map of the chromosome segment surrounding Gro1, based on RFLP, RAPD and AFLP markers. RAPD and AFLP markers closely linked to Gro1 were selected by bulked segregant analysis and mapped relative to the Gro1 locus in a segregating population of 1105 plants. Three RFLP and one RAPD marker were found to be inseparable from the Gro1 locus. Two AFLP markers were identified that flanked Gro1 at genetic distances of 0.6 cM and 0.8 cM, respectively. A genetic distance of 1 cM in the Gro1 region corresponds to a physical distance of ca. 100 kb as estimated by long-range restriction analysis. Marker-assisted selection for nematode resistance was accomplished in the course of constructing the high-resolution map. Plants carrying the resistance allele Gro1 could be distinguished from susceptible plants by marker assays based on the polymerase chain reaction (PCR).

Cloning and expression of genomic DNA sequences coding for putative erythrocyte membrane-associated antigens of Plasmodium falciparum.

Genomic DNA fragments of Plasmodium falciparum generated by mung bean nuclease digestion were cloned in the lambda expression vector lambda JK2. The resulting library was screened with a rabbit antiserum raised against purified membranes of P. falciparum-infected erythrocytes and with a serum pool from immune humans from an endemic area of Liberia. Positive clones were rescreened with a series of human and monkey sera. Twelve selected clones were analysed in detail. Four of them corresponded to already described membrane-associated P. falciparum antigens. The other positive clones contained inserts which, according to the nucleotide sequence, Southern blot analysis and immunological characteristics, correspond to so far unknown antigens.

Callus induction and plant regeneration in Panicum bisulcatum and Panicum milioides.

Surface sterilized seeds and mesocotyls from sterile seedlings from Panicum bisulcatum Thumb., as well as basal parts of leaves and mesocotyls from sterile seedlings, and seeds from Panicum milioides Nees ex. Trin were used as explants to induce callus on a Murashige and Skoog medium supplemented with 2.5 to 10 mg/l of 2,4-D. Subculturing of the white callus from P. milioides and of the brown callus from P. bisulcatum on a medium containing 0.1 mg/l 2,4-D and 10 g/l sucrose led in both species to the appearance of green structures from which plants could be regenerated. Plants were regenerated by an organogenetic process in P. milioides, while P. bisulcatum plants were regenerated both via organogenesis and somatic embryogenesis. 1032 and 94 plants, from P. bisulcatum and P. milioides, respectively, were transferred into soil, and about 90% of them were grown to maturity and set seeds.