Unlocking the potential of self-healing and recyclable ionic elastomers for soft robotics applications.

In the field of soft robotics, current materials face challenges related to their load capacity, durability, and sustainability. Innovative solutions are required to address these problems beyond conventional strategies, which often lack long-term ecological viability. This study aims to overcome these limitations using mechanically robust, self-healing, and recyclable ionic elastomers based on carboxylated nitrile rubber (XNBR). The designed materials exhibited excellent mechanical properties, including tensile strengths (TS) exceeding 19 MPa and remarkable deformability, with maximum elongations (EB) over 650%. Moreover, these materials showed high self-healing capabilities, with 100% recovery efficiency of TS and EB at 110 °C after 3 to 5 h, and full recyclability, preserving their mechanical performance even after three recycling cycles. Furthermore, they were also moldable and readily scalable. Tendon-driven soft robotic grippers were successfully developed out of ionic elastomers, illustrating the potential of self-healing and recyclability in the field of soft robotics to reduce maintenance costs, increase material durability, and improve sustainability.

[Risk profiling of postoperative complications in 17,644 total knee replacements]. / Identifizierung von Risikofaktoren postoperativer Komplikationen in der primären Knieendoprothetik.

AIM: Postoperative complications following primary total knee replacement performed between 2000 and 2002 were assessed to determine perioperative patient- and procedure-related risks associated with the procedure. METHODS: For this analysis, the data collected during postoperative hospitalization for 17,644 total knee arthroplasties were assessed. The analysis included two steps. First, using logistic regression, we identified and quantified significant risk factors for the occurrence of general postoperative complications. Second, univariate analysis was utilized to qualitatively and quantitatively analyze the influence of these significant risk factors on the occurrence of major complications (hematoma, cardiovascular complication, deep venous thrombosis, pulmonary embolism, joint infection, and pneumonia). RESULTS: General postoperative complications were reported in 11.3%. Major postoperative complications occurred in 7.2% with hematoma in 2.9%, cardiovascular complications in 1.8%, deep venous thrombosis in 1.2%, pulmonary embolism in 0.2%, joint infection in 0.8%, and pneumonia in 0.3%. Patient-related risk factors such as age, surgery time, gender, high ASA classification as well as procedure-related risk factors such as allogeneic blood transfusions and lateral release significantly increased the rate of postoperative complications. Males were more prone to hematoma, joint infection, and pneumonia in the immediate postoperative course than females, who were more in danger of developing deep venous thrombosis. Allogeneic blood transfusions increased the risk for postoperative hematoma, infection, and cardiovascular complication. Regional anesthesia was shown to decrease the risk for the occurrence of postoperative deep venous thrombosis and pulmonary embolism. CONCLUSIONS: Postoperative complications in total knee replacement are increased in males and elder patients. Increased time of surgery and allogeneic blood transfusions also represent important risk factors for postoperative complications following primary total knee replacement.

Synthesis of cyclic dipeptide templates, their incorporation into peptides and studies on their conformational and biological properties.

This study investigated the diastereoselective synthesis of three dipeptide templates 1, 2 and 3, which may be regarded as conformationally restricted analogs of H-Gly-Xaa-OH, in which Xaa constitutes an aromatic amino acid. Bond formation between alpha-C of Gly and the aromatic moiety was achieved by proton-catalyzed intramolecular electrophilic aromatic substitution. The absolute configuration of the dipeptide templates was determined by single-crystal X-ray crystallography or by nuclear Overhauser enhancement measurements. A protective group strategy was elaborated to allow their incorporation into peptide sequences by liquid phase as well as by solid-phase peptide synthesis. The templates were used to generate an enkephalin analog 15, a modified peptidic neurokinin antagonist 20 and two dermorphin derivatives (24 and 33). Molecular dynamic simulations with 15 and 20 revealed the preference for a turn-like motif for 15. The biological activity, as investigated by respective receptor binding and functional assays, was strongly diminished with all four derivatives, indicating that their receptor-relevant molecular geometries lie outside the examined conformational space.

On the trail of Dr. Fifer.

A gift from a patient drew Hope, BC, family physician Gerd Asche irrevocably into the local medical history of the 1858 Fraser River Gold Rush. Because of his interest in Dr. Max William Fifer, Asche undertook research missions in British Columbia, England and the US, converted his computer room to a research and writing centre, and wrote a biography of his predecessor and colleague. He recounts his experience and the growing satisfaction provided by his interest in medical history.

[Treatment of radius fractures with a newly developed dynamic external fixator]. / Die Behandlung von Speichenbrüchen mit einem neu entwickelten dynamischen Bewegungsfixateur.

Ligamentotaxis first described by Vidal presented the opportunity to treat wrist fractures near to the joint with external fixation. The first published results with this technique were surprisingly successful. As a result, since 1980 the author began, as one of the first in the German speaking regions, to treat radius fractures with the Hoffmann C-series external fixator. With a newly developed dynamic wrist fixator device 4 clinics have treated 104 fractures in a prospective study. These fractures were followed up 6 months later. Using the Lidström classification, the x-ray results were very good and good for 98% and moderate for 2% of treated fractures. Clinically the results were very good and good for 91% and moderate for 2% of treated fractures. Poor results were not recorded. 92% of the patients had a shortening of the radius of less than 2 mm. The sooner motion was initiated, the better the results were during the follow up. All the parameters such as x-ray evaluation, clinical evaluation, pain, strength, and in particular motion were improved when compared to a static fixator or motion after 14 postoperative days. The treatment time with this new dynamic wrist fixator device was reduced by two weeks compared to a static fixator. Cancellous bone grafting was never necessary.

Comparison of measured carbon dioxide production with that obtained by the isotope dilution technique in neonatal pigs: observations on site of infusion.

Fifteen newborn pigs (1.5 kg) were used to estimate CO2 "production" over a 5-h experiment. In each piglet, the average expired air CO2 irreversible loss rate measured over 15-min intervals was compared with an estimate of CO2 "produced" by a continuous infusion of NaH14CO3 into either the aortic artery (seven pigs) or the portal vein (eight pigs). The specific radioactivity (Bq/mumol) of the expired CO2 taken over consecutive 15-min intervals during the 5-h period was fitted to an exponential model to predict the specific radioactivity at steady state. This specific radioactivity was used to calculate the total CO2 irreversible loss rate and to correct for the difference in tracer infused in relation to tracer excreted at 5 h (76 to 78%). The estimated CO2 "produced" tended to be higher (P < 0.12) when the aortal rather than the portal infusion site was used [571 vs. 498 mumol/(min.kg0.75)]. The isotope dilution technique significantly (P < 0.05) overestimated the expired air CO2 regardless of whether the aortal [571 vs. 469 mumol/(min.kg0.75)] or portal [498 vs. 447 mumol/(min.kg0.75)] routes of infusion were used.

[A possibly shorter time of fracture healing by implantation of the new dynamic rolling rod]. / Eine Möglichkeit kurzer Frakturheilung durch den Einsatz des neuen dynamischen Gleitstabes Rolling Rod.

Two different ideas brand the opinions about the healing of fractures. Since 1965, Burny purses the idea of secondary bone-healing and for this he has developed mathematic patterns. With the elastic fixateur-fitting, he has proved that a small measure of surplus movement is necessary in the area of the fracture. Since 1979 we in Freudenstadt have used these principles of treatment and also could arrive as stable callus-formation with use of halve frame fitting. Since 1987, we use the dynamic rod Rolling Rod, which enables a dynamic axial compression in the fracture. This compression is achieved by the exellent sliding ability even in the oblique fitting required in fixateur-fitting in the vicinity of the corticalis. In comparing two similar groups of patients with the same type of fracture and nearly same duration of fixateur proved, that the group of patients treated with the Rolling Rod arrived as the required bone firmness for full weight-bearing one month earlier. By considering these healing results in connection with the elastic fractur fixation one should scrutinize again the rigid osteosynthesis.

[Dynamic treatment of para-articular wrist and articular radius fractures with a new kind of dynamic fixation]. / Die dynamische Behandlung von handgelenksnahen und gelenksbeteiligten Speichenbrüchen mit einem neuartigen Bewegungsfixateur.

During a period of almost ten years with 280 cases, experience has been gathered in connection with the immobilisation of radius fractures, in the vicinity of the wrist, by means of the fixateur externe. The good x-ray and functional results, overshadowed by the long physiotherapy later, have always aroused the wish for early mobilisation coincidal with the fixateur. The hither to wellknown movable fixateur such as that from Cleyburn have the disadvantage that the mounting of the apparatus can first be carried out after the reduction of the radius-fracture. Jonsson suggested a movable fixateur, that could be attached to the well-known Midifixateur of Hoffmann. In collaboration with the Howmedica company, we further developed this apparatus so that the wrist could remain active even under the necessary traction. The first six patients treated with this type of apparatus stood out from the rest, after removal of the fixateur, due to the instant and satisfactory mobility of the wrist. Needless to say, by using this movable apparatus, the lengths of treatment and line off work can be drastically reduced to a minimum. The movable fixateur will be on the market and obtainable in the near future.

Protein digestion in weanling pigs: effect of feeding regimen and endogenous protein secretion.

Protein digestion and absorption were measured in weanling pigs (5 wk of age) using a total digesta collection procedure. In the first experiment, the objective was to measure the fate of nitrogenous digesta as it passed from the stomach to the terminal ileum when pigs were either allowed ad libitum access to feed or were fed four equal meals per day. Pigs were fed a standard corn-soybean meal diet in this experiment. There were no differences in flow rate or retention time of dry matter or nitrogen, and no differences in apparent nitrogen digestibility between the two feeding regimens. More than 80% of the soluble protein in the stomach and 65% in the small intestine was between 2,000 and 15,000 molecular weight. The molecular weight profiles of the soluble proteins were relatively constant throughout the small intestine, indicating that the products of protein hydrolysis were absorbed rapidly. The objective of the second experiment was to compare protein digestion and absorption in pigs fed a corn-soybean meal diet with those fed a protein-free diet. The molecular weight profiles of soluble protein were similar for the two groups of pigs. The data indicate that most of the endogenous enzymes were hydrolyzed rapidly, since little soluble protein corresponding to the molecular weight of pancreatic enzymes was detected.

Protein digestion in weanling pigs: effect of dietary protein source.

The digestion and absorption of dietary protein was measured in weanling pigs (5 wk of age). Diets containing corn and either dried skim milk (DSM), soybean meal (SBM) or corn gluten meal (CGM) were fed for 7 d, and the contents of the stomach and six segments of the small intestine were collected. Nitrogen digestibility increased linearly from the proximal duodenum to the distal ileum, and was highest for DSM, intermediate for SBM and lowest for CGM diets at the distal ileum. The content of free amino acids in digesta increased 8-fold (SBM and CGM) to 12-fold (DSM) between the stomach and the proximal duodenum and reached a maximum concentration in the distal jejunum. Digestion of DSM was more proximal than was that of SBM. Although there was some accumulation of small peptides in the duodenum with a subsequent decrease in the jejunum, the molecular weight profiles of the soluble proteins were relatively constant throughout the small intestine. Protein solubility and the rate of proteolysis in the stomach and upper small intestine were the primary factors that limited the digestion of SBM and CGM.

[Results of the treatment of femoral and tibial fractures following interlocking nailing and plate osteosynthesis. A comparative retrospective study]. / Behandlungsergebnisse von Ober- und Unterschenkelfrakturen nach Verriegelungsnagelung und Plattenosteosynthese. Eine vergleichende retrospektive Studie.

The Howmedica lock nail was introduced to an ordinary hospital where femoral and crural fractures had been stabilised in the past almost exclusively by plate-type osteosynthesis. Since only minor change had taken place regarding surgeons and surgical environment, the decision was taken to compare two groups of patients with lock nailing and plate-type osteosynthesis. Most of the nailing patients could immediately expose the injured extremity to load. Hospitalisation for them was as short as twelve days on average. They were fit for work not later than six months from surgery. Plate-type osteosynthesis patients, on the other hand, were hospitalised five weeks, on average. None of the patients could fully use his or her leg, after two months. Pseudoarthrosis was quite frequent in the wake of plate-type osteosynthesis but was not observed at all after lock nailing. The risk of posttraumatic osteomyelitis was considerably reduced. Covered nailing proved to be applicable to the majority of cases. A specifically designed image converter was used in cases of distal locking. Lock nailing proved to provide a great number of advantages, with cost saving being one of them. It is a routine method that can be used at any general hospital, once the surgical team on the spot has been familiarised with the technique.

Effect of dry, high-moisture and reconstituted normal and high-lysine corn diets and particle size on energy and nitrogen metabolism in growing swine.

Two metabolism studies were conducted with 24 (Exp. 1) and 36 (Exp. 2) crossbred barrows (initial weight 35 kg) to determine the effect of corn type--normal corn (NC) and high-lysine corn (HLC)--and storage method--dry (D), high-moisture (HM) and reconstituted (RC)--on energy and N digestibility. Diets fed in Exp. 1 were: 1, NC-soybean meal formulated at .78% lysine (dry matter basis); 2, HLC-soybean meal containing the same amount of corn as diet 1 (.87% lysine); 3, HLC-soybean meal with the same lysine level as diet 1. In Exp. 1, dry matter, energy and N digestibilities were not different between corn types or lysine levels (P greater than .16). These results indicate that energy and N digestibility of HLC in typical diets for growing swine are similar to those for NC diets when both are balanced on a lysine basis. Also, replacing NC with HLC on an equal-weight basis did not affect energy and N digestibility. In Exp. 2 six diets balanced on an isonitrogenous and dry-matter basis were tested. Normal corn and HLC diets, which had been stored by three different methods (D, HM and RC) were arranged in a 2 X 3 factorial plan. There were no differences between corn types in dry matter, energy and N digestibilities. The HM and RC treatments had larger particle sizes than the dry corn diets. For diets balanced on an isonitrogenous basis, dry corn storage improved energy digestibility (P less than .10). Reconstitution appeared to improve energy balance and N digestibility of HLC, while HM storage improved energy balance and N digestibility of NC.

[Gentamicin PMMA minichains in infections of the hand]. / Gentamicin-PMMA-Miniketten bei Infektionen der Hand.

Hitherto a prolonged treatment and immobilization was necessary in case of bone and soft tissue infections of the hand. The result was frequently a poor function of the hand due to ankylosis. The infection period can be shortened by an early, carefully performed sequestrotomy with additional temporary implantation of gentamicin-PMMA minichains. The evaluation of 200 cases shows the good results of this therapy method.

[Use of external fixation in pediatric fractures]. / Die Anwendung des Fixateur externe bei kindlichen Frakturen.

Conservative treatment is usually applied to fractures in childhood. However, stabilisation of such fractures is necessary for certain indications. Indications for stabilisation are specified, and a new technique for stabilisation is described. Fractures were stabilised in 40 children, using a clamp-type fixator. In this context, Hoffmann's external fixator is recommended for cases of closed resetting, since additional and corrective resetting would then be possible even after application of bone nails and apparatus. The following advantages are likely to be provided by the above approach: reduced time of hospitalisation, very early possibility of mobilisation and exposure to loading, minor traumatisation in the course of stabilisation of such fractures. No blood transfusion has ever been necessary for blood supply to patients with femoral fractures. Absence from school has been minimized. This surgical approach has proved to be simple and of low-risk nature, as compared to plate osteosynthesis.

The nutritional value of normal and high lysine corns for weanling and growing-finishing swine when fed at four lysine levels.

One-hundred-ninety-two weanling pigs from two separate trials, (initial weight 6.0 and 5.6 kg) and 400 growing-finishing pigs (initial weight 17 kg) were fed normal and high lysine corn diets containing four levels of lysine in a 2 X 4 factorial arrangement. Crossbred (Large White X Landrace X Duroc) pigs were used in all experiments. The objectives of the experiments were to (1) compare normal and high lysine corn when fed at different lysine levels, (2) determine the lysine requirements for the three stages of growth and (3) evaluate the effect of protein level on the lysine requirement. All diets were balanced on a lysine basis. The results indicated that both weanling and growing-finishing pig performance and final carcass composition were similar for pigs fed normal or high lysine corn diets balanced on a lysine basis. Weanling pigs from 5 to 14 kg required at least 1.10% lysine. Based on changes in body weight gain and feed efficiency, the lysine requirement of growing pigs (17 to 54 kg) was .70%, and that of finishing pigs (54 to 101 kg) was .50%. However, based on lean tissue growth rate (as reflected by longissimus muscle area and percentage of lean in the carcass) the requirement was at least .75% during the growing stage and .60% during the finishing stage. The reduced protein level (2% lower) of the high lysine corn diets did not reduce the lysine required by pigs compared with those fed normal corn.

[Possibility of the para-articular finger fractures with external minifixation]. / Stabilisierungsmöglichkeit fingergelenksnaher Frakturen mit dem Minifixateur externe.

Use of external minifixation is shown for the stabilization of finger fractures in more then one hundred cases. The author shows that this technique is applicable in intra-articular fractures.

[Treatment of palmar and tendon sheath infections following aponeurectomy with gentamycin PMMA minichains]. / Behandlung einer Hohlhand- und Sehnenscheiden-Phlegmone nach Aponeurektomie mit Gentamycin-PMMA-Miniketten.

Soft tissue and bone infections of the hand often require long-term treatment. In most cases this will result in a poor function. In a case of infection after aponeurectomy it is shown that early revision and local therapy with Gentamycin-PMMA-minichains bring very good results, as we have already shown in more than two hundred cases.

[External fixation as an aid in plastic surgery]. / Der Fixateur externe als Hilfsmittel bei plastischen Operationen.

Today, reconstructive surgery knows many different skin flaps for treating soft tissue defects. The advantages of Hoffmann's external anchorage are demonstrated by immobilizing skin flaps during their process of healing.

External fixation of the fracture of the humerus: a review of 164 cases.

During our experience with external fixation for the fractures of the shaft of the humerus since 1967, the indications have been extended to include complex metaphyseal and epiphyseal fractures of both the proximal and the distal part of the bone. We propose elastic fixation of the fragments using half frame Hoffmann external fixation. Because of anatomical considerations, the two proximal pins must be inserted laterally in the upper third of the humerus, and the two distal pins in the posterior aspect of the lower third above the olecranon fossa. If the mechanical properties of the bone are poor (due to osteoporosis) more than two pins must be used in each fragment. The advantages of the technique include fast and easy application requiring simple materials; versatility of use for fractures at different levels; possible closed reduction, as in conservative treatments; early rehabilitation of joint function; fast periosteal callus formation; and retrieval of the fixator on an outpatient basis.The reduction and the immobilization of the fracture by osteotaxis are done in emergency. Closed reduction is performed as in conservative treatments. In cases of important muscular interposition, open reduction is possible. Associated internal fixation was required in 18.4% (unstable or articular fractures). A secondary transient radial palsy is observed in 5% of the patients. Intolerance to the external fixation appears in 5.6% of cases, usually consisting of drain age and redness around the pin tracts. A general evaluation of the results gives 73.8% very good results and 93.6% satisfactory results after rehabilitation.