Numerical and experimental study on mechanical behaviour of the AlSi10Mg aluminium structures manufactured additively and subjected to a blast wave

The paper is related to energy absorptive properties of additively manufactured metallic cellular structures. The samples of Honeycomb, Auxetic, rhomboidal Lattice and a regular Foam are subjected to a dynamic compression due to the blast tests. The cuboidal samples are manufactured by the Direct Metal Laser Sintering (DMLS) method using AlSi10Mg aluminium powder. The experimental tests are performed by means of an Explosive Driven Shock Tube (EDST). The measured results of the transmitted forces in relation to the shortening of the samples allow to analyse the deformation processes of each selected geometry. In addition, the evaluation of the structural responses leads to identification of the structure properties, such as the equivalent stress over equivalent strain or the energy absorption per a unit of mass. Moreover, the process of compression is modelled numerically using the explicit code LS-DYNA R9.0.1. The obtained simulations provide the complete analysis of the experimentally observed mechanisms.

Elevated percentage of HLA-DR⁺ and ICAM-1⁺ conjunctival epithelial cells in active Graves' orbitopathy

Background

To evaluate if conjunctival epithelial cells’ expression of HLA-DR and ICAM-1 could be helpful as early topical markers of inflammation in Graves’ orbitopathy (GO).

Methods

The ocular examination evaluated a clinical activity score (CAS) by assessment of clinical features, (e.g., eyelid or conjunctival inflammation, lid width, lid closure, proptosis, ocular motility). Conjunctival epithelial cell specimens for flow-cytometric evaluations of ICAM-I and HLADR expression were collected by impression cytology from ten eyes with active GO (CAS ≥ 4 and duration ≤ 12 months), from 15 eyes with Graves’ disease (GD) without active GO (CAS 0–2) and from 15 normal specimens without any ocular disorders.

Results

The percentage of HLA-DR + conjunctival epithelial cells was significantly elevated in patients with active GO comparing to GD without active GO and healthy controls, 10.7 % (8.5–17.7) and 7.78 % (3.92–10.1) (p < 0.05) vs. control 4.89 % (3.5–5.5) (p < 0.005), respectively. The expression of ICAM − 1+ conjunctival epithelial cells was greater only in patients with GO vs. controls, 5.5 % (4.8–7.03) and 1.46 % (0.69–2.51) (p < 0.005), respectively.

Conclusion

The percentage of HLA-DR⁺ and ICAM-1⁺ conjunctival epithelial cells in patients with the active GO may serve as a topical inflammation marker in Graves’ orbitopathy.

Coincidence measurement of residues and light particles in the reaction 56Fe+p at 1 GeV per nucleon with the spallation reactions setup SPALADIN

The spallation of 56Fe in collisions with hydrogen at 1A GeV has been studied in inverse kinematics with the large-aperture setup SPALADIN at GSI. Coincidences of residues with low-center-of-mass kinetic energy light particles and fragments have been measured allowing the decomposition of the total reaction cross section into the different possible deexcitation channels. Detailed information on the evolution of these deexcitation channels with excitation energy has also been obtained. The comparison of the data with predictions of several deexcitation models coupled to the INCL4 intranuclear cascade model shows that only GEMINI can reasonably account for the bulk of collected results, indicating that in a light system with no compression and little angular momentum, multifragmentation might not be necessary to explain the data.

Pharmacokinetics of florfenicol, thiamphenicol, and chloramphenicol in turkeys

The pharmacokinetics of florfenicol (FF), thiamphenicol (TP) and chloramphenicol (CP) after single intravenous (i.v.) or oral (p.o.) administration was studied in an independent cross-over study in broiler turkeys. All the fenicol antibiotics were administered at a dose of 30 mg/kg b.w. and their concentrations in plasma samples were assayed using the same validated high-performance liquid chromatography method. Pharmacokinetic parameters were calculated by a noncompartmental method. The kinetic profiles of the compounds were compared with the results of the structure-activity relationship. According to the proposed mathematical description, no differences in plasma clearance values for the studied antibiotics were observed. The mean residence time values of FF, TF, and CP after i.v. injection were 3.37+/-0.63, 2.43+/-0.29, and 2.12+/-0.21 h, respectively. The mean values of Varea for FF (1.39+/-0.31 L/kg) and TP (1.31+/-0.19 L/kg) were similar, but significantly different from that of CP (1.04+/-0.12 L/kg). The bioavailabilities of FF, TP, and CP after oral administration were 82%, 69%, and 45%, respectively. Differences in the bioavailability values of the compared fenicol antibiotics correspond to the ratio of the apolar/polar surface areas of their particles.

Mechanisms involved in the relaxing effect of midazolam on coronary arteries

BACKGROUND AND OBJECTIVE

Hypotension, especially in elderly and hypovolaemic patients, is frequently associated with intravenous midazolam administration. The mechanisms are not completely understood. This study was designed to investigate the mechanisms involved in the relaxing effect of midazolam on coronary arteries.

METHODS

The substance was studied in isolated porcine coronary artery rings precontracted by either potassium chloride or prostaglandin F2alpha.

RESULTS

Midazolam caused vasodilatation in a concentration-dependent manner. Relaxation was more pronounced in prostaglandin F2alpha precontracted segments than in those treated with potassium chloride (P < 0.001). Vasodilatation was unaffected by Nomega-nitro-L-arginine, indomethacin and glibenclamide. Tetraethylammonium chloride, an inhibitor of the BK(Ca) K+ channel (a high conductance Ca(2+)-sensitive K+ channel), dose dependently attenuated the vasodilating effect of midazolam (P < 0.01).

CONCLUSIONS

Hyperpolarization of the smooth muscle cell in the vessel wall, elicited by the activation the BK(Ca) K+ channel, may contribute to the vasorelaxing effect of midazolam.

Evidence for spinodal decomposition in nuclear multifragmentation

Multifragmentation of a "fused system" was observed for central collisions between 32 MeV/nucleon 129Xe and (nat)Sn. Most of the resulting charged products were well identified due to the high performances of the INDRA 4pi array. Experimental higher-order charge correlations for fragments show a weak but nonambiguous enhancement of events with nearly equal-sized fragments. Supported by dynamical calculations in which spinodal decomposition is simulated, this observed enhancement is interpreted as a "fossil" signal of spinodal instabilities in finite nuclear systems.

Electrorheological modeling of the permeabilization of the stratum corneum: theory and experiment

Experimentally observed changes in the conductivity of skin under the influence of a pulsing electric field were theoretically analyzed on the basis of a proposed electrorheological model of the stratum corneum (SC). The dependence of relative changes in conductivity on the amplitude of electric field and timelike parameters of applied pulses or pulse trains have been mathematically described. Statistical characteristics of phenomena of transient and long-term electroporation of SC were taken into consideration. The time-dependent decreases of skin resistance depicted by the models were fitted to experimental data for transient and long-term skin permeabilization by electric pulses. The results show two characteristic times and two spectra of characteristic energies for transient and long-term permeabilizations. The rheological parameters derived from the fittings agreed with those reported elsewhere for biological membranes.

[Monozygotic multiple pregnancies with acardiac anomalies]

The acardiac fetus is a rare anomaly of about 1 percent of monozygotic pregnancies, occurring in approximately 1 in 35,000 pregnancies. The special hemodynamic circumstances of the normal heart having to pump an excessive amount of blood for a long period of time will influence the chance of survival of this fetus. In two case-report with many figures pathologic-anatomical problems and prospective management to improve the outcome of monozygotic multiple pregnancies complicated by acardiac malformation were presented. The pathogenesis of metabolic dysbalance in these pregnancies was discussed.

Bioelectrorheological model of the cell. 7. Cellular deformation in the presence of cytochalasin B

The influence of cytochalasin B on the mechanical properties of Neurospora crassa cells subjected to a periodic electric field was investigated. Shear and extensional deformations were considered and studied separately. Conditions were found under which shear deformations become irreversible. Rheological models helped in the interpretation of the results in terms of the different response to the shear stress of the three hypothetical supramolecular regions of the membrane-skeleton network (F, S and 0). Rheological parameters for the above regions related to the proposed models were calculated. The models were satisfactorily fitted to the experimental results. The influence of cytochalasin B on the course of extensional deformation of cells was investigated and characterized semiquantitatively.

Bioelectrorheological model of the cell. VI. Experimental verification of the rheological model of cytoplasmic membrane

The susceptibility of the Neurospora crassa (slime) cellular membrane to electroporation and electrodestruction in an alternating electric field was further investigated. The results were analyzed according to the dynamic rheological model of the cytoplasmic membrane. Based on an analytical description of membrane susceptibility to electroporation, the rheological parameters of the foregoing process in N. crassa cellular membrane were found: they closely resemble those previously determined for the membranes' destruction. This suggests that both processes are temporally related and are induced within the same structures of the membrane. The dependence of the destruction of the membrane on the time of application and the frequency of the electric field was theoretically predicted and experimentally confirmed.

Bioelectrorheological model of the cell. 2. Analysis of creep and its experimental verification

The electrorheological model of the cell proposed in Part 1 of this work was used to analyze changes in time of the shape of a cell acted on by a constant-amplitude external alternating electric field, with lossiness of the media taken into account. Shear stress in the cell membrane was determined. This model was then subjected to preliminary experimental verification using Neurospora crassa (slime) spheroplasts subjected to an external alternating electric field of constant frequency (3 MHz) and varying magnitude for different periods of time. Reversible viscoelastic cell deformation and fatigue (stiffening) of the material were observed. A satisfactory fit of the experimental data to Burgers' rheological model was found, and the values of the elastic moduli E1 = 9 X 10(2) N/m2, E2 = 2 X 10(2) N/m2 and viscosities eta 1 = 8 X 10(4) Ns/m2; eta 2 = 7 X 10(3) Ns/m2 were evaluated.

Bioelectrorheological model of the cell. 1. Analysis of stresses and deformations

An electrorheological model of a cell in alternating electric field is proposed. The model relates changes in the spherical cell's shape to the field conditions, electric parameters of cytoplasm, cell membrane and external medium, and to the rheological parameters of the membrane. Stresses were determined using Maxwell's stress tensor for isotropic media. Shear stresses in the cell membrane were analyzed. Predictions of the model for variations of shear stress in cellular membranes subjected to an external periodic electric field are presented and related to the conditions prevailing in electrobiological research.

[Pylephlebitis after umbilical vein catheterization (author's transl)]

In spite of extensive precausions and antibiotic therapy, pylephlebitis was found in 11 of 200 dead newborns as complicat infection after umbilical vein catherization. All stages from local pylephlebitis to suppurative hepatitis were found. The clinical manifestations are not characteristic and therefore misinterpreted very often. Umbilical vein infection should be taken into account in every newborn child with or after umbilical vein catheterization, even when the umbilicus appears normal, when body temperature is rising, the general condition is turning to the worse, and icterus is increasing. Blood picture and transaminase values might be helpful parameters. Reviewing the literature and reporting a case of fatal portal hypertension, pylephlebitis after umbilical vein catheterization is shown as a possible cause of the pseudo-Banti-syndrome in children.

Anemic necrosis of the liver after umbilical vein catheterization

We report 22 cases of hepatic necrosis following catheterization of the umbilical vein. The morphology of the necrotic lesions, which were confined to the left lobe in 21 patients, was that of an anemic infarct. Their causes are multiple and include intimal damage during the insertion of the catheter with consecutive thrombosis of portal vein branches, the postpartum immaturity of the arterial hepatic oxygen supply, postpartum hypoxia due to respiratory failure of cerebral or pulmonary origin, obstruction of portal venous flow through the catheter as such, the postpartum involution of the left hepatic lobe, and prolonged periods of catheterization. Toxic damage of the hepatic parenchyma due to an infusion of Tris buffer through the catheter into the portal venous system is a potential additional factor.

[Laryngeal complications in newborns following intratracheal intubation (author's transl)]

Histological and bacteriological findings in comparison to clinical data concerning intubation for 38 dead premature infants and newborns were studied to elucidate conditions complicating intratrachial intubation at the laryngeal level. The larynx was intact in 3 cases. Slight lesions of mucosa (epithelabrasion, hemorrhage) were found in 13, moderately severe lesions (necrosis of epithelium, ulcers, pseudomembranes) in 11, and severe lesions (deep necrosis, perichondritis with sceletisation) in 10 cases. 1 case showed a stage of regeneration. The narrow passage between the two processus vocales is a site of predilection for tubus-induced lesions, the epithelium bein immediately adjacent to the cartilage. Successful bacteriological demonstration of the infectious agent correlated with the rising degree of mucosal lesions, and increasing duration of intubation. 3 cases, however, already had severe lesions after short-time-intubation. Formal and causal pathogenesis are described. Essential causes are: trauma of intubation, irritation by the tubus in situ, duration of intubation, and infection. Regenerative power of the infantile laryngeal mucosa is strong. Permanent lesions may occur as scarred stenosis. Careful indication, accurate and careful technology of intubation, choice of the smallest possible diameter of tubus, good care for the tubus, and generous prophylaxis against infections are to be demanded.

Isolated histone fractions and the alkaline fast green reaction

When the alkaline fast green reaction is applied to calf thymus histone fractions f1, f2a, f2b and f3 on Millipore filter paper it is found to stain equal amounts of these fractions equally well. The dye reaction, therefore, seems to depend on the over-all charge and not exclusively on the per cent arginine plus lysine in the histone fractions. This staining reaction has been applied to histone fractions separated by acrylamide gel disc electrophoresis. Deamination of the histone fractions on both paper and acrylamide gel resulted in a reduction in the intensity of the stain. The stain that remained followed the relative amount of arginine in each fraction or band. In the gels, the f1 band was removed completely. This confirms previous interpretations of the cytochemical deamination reaction. The stain reactions have been utilized as a means of comparing electrophoretically resolved histone bands of similar mobility from crickets and mealy bugs.