The Case of the Unwanted Blessing: Wrongful Life

The recognition of a cause of action for wrongful life is a relatively recent occurrence. In this article the author compiles the leading cases from many jurisdictions and presents an analytical framework for the treatment thereof. The author concludes by presenting the policy arguments in favor of allowing a cause of action for the cases which are loosely and inappropriately termed wrongful life

The Case of the Unwanted Blessing: Wrongful Life

The recognition of a cause of action for wrongful life is a relatively recent occurrence. In this article the author compiles the leading cases from many jurisdictions and presents an analytical framework for the treatment thereof. The author concludes by presenting the policy arguments in favor of allowing a cause of action for the cases which are loosely and inappropriately termed wrongful life

Development of 3D PCL microsphere/TiO\u3csub\u3e2\u3c/sub\u3e nanotube composite scaffolds for bone tissue engineering

In this research, the three dimensional porous scaffolds made of a polycaprolactone (PCL) microsphere/TiO2 nanotube (TNT) composite was fabricated and evaluated for potential bone substitute applications. We used a microsphere sintering method to produce three dimensional PCL microsphere/TNT composite scaffolds. The mechanical properties of composite scaffolds were regulated by varying parameters, such as sintering time, microsphere diameter range size and PCL/TNT ratio. The obtained results ascertained that the PCL/TNT (0.5 wt%) scaffold sintered at 60 °C for 90 min had the most optimal mechanical properties and an appropriate pore structure for bone tissue engineering applications. The average pore size and total porosity percentage increased after increasing the microsphere diameter range for PCL and PCL/TNT (0.5 wt%) scaffolds. The degradation rate was relatively high in PCL/TNT (0.5 wt%) composites compared to pure PCL when the samples were placed in the simulated body fluid (SBF) for 6 weeks. Also, the compressive strength and modulus of PCL and PCL/TNT (0.5 wt%) composite scaffolds decreased during the 6 weeks of storage in SBF. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay and alkaline phosphates (ALP) activity results demonstrated that a generally increasing trend in cell viability was observed for PCL/TNT (0.5 wt%) scaffold sintered at 60 °C for 90 min compared to the control group. Eventually, the quantitative RT-PCR data provided the evidence that the PCL scaffold containing TiO2 nanotube constitutes a good substrate for cell differentiation leading to ECM mineralization

Allosteric serine hydroxymethyltransferase from monkey liver: Temperature induced conformational transitions

The homogeneous serine hydroxymethyltransferase from monkey liver was optimally activate at 60° C and the Arrhenius plot for the enzyme was nonlinear with a break at 15° C. The monkey liver enzyme showed high thermal stability of 62°C, as monitored by circular dichroism at 222 nm, absorbance at 280 nm and enzyme activity. The enzyme exhibited a sharp co-operative thermal transition in the range of 50°-70° (Tm= 65°C), as monitored by circular dichroism. L-Serine protected the enzyme against both thermal inactivation and thermal disruption of the secondary structure. The homotropic interactions of tetrahydrofolate with the enzyme was abolished at high temperatures (at 70°C, the Hill coefficient value was 1.0). A plot of h values vs. assay temperature of tetrahydrofolate saturation experiments, showed the presence of an intermediate conformer with an h value of 1.7 in the temperature range of 45°-60°C. Inclusion of a heat denaturation step in the scheme employed for the purification of serine hydroxymethyltransferase resulted in the loss of cooperative interactions with tetrahydrofolate. The temperature effects on the serine hydroxylmethyltransferase, reported for the first time, lead to a better understanding of the heat induced alterations in conformation and activity for this oligomeric protein

Allosteric serine hydroxymethyltransferase from monkey liver: correlation of conformational changes caused by denaturants with the alterations in catalytic activity

The far-ultraviolet region circular dichroic spectrumof serine hydroxymethyltransferase from monkey liver showed that the protein is in an a-helical conformation. The near ultraviolet circular dichoric spectrum revealed two negative bands originating from the tertiary conformational environment of the aromatic amino acid residues. Addition of urea or guanidinium chloride perturbed the characteristic fluorescence and far ultraviolet circular dichroic spectrum of the enzyme. The decrease in (θ )222 and enzyme activity followed identical patterns with increasing concentrations of urea, whereas with guanidinium chloride, the loss of enzyme activity preceded the loss of secondary structure. 2-Chloroethanol, trifluoroethanol and sodium dodecyl sulphate enhanced the mean residue ellipticity values. In addition, sodium dodecyl sulphate also caused a perturbation of the fluorescence emission spectrum of the enzyme. Extremes of pH decreased the - (θ )222 value. Plots of -(θ )222and enzyme activity as a function of pH showed maximal values at pH 7.4-7.5. These results suggested the prevalence of "conformational flexibility" in the structure of serine hydroxymethyltransferase

Graphene nanoplatelet-based nanocomposites: electromagnetic interference shielding properties and rheology

Polymer nanocomposites, produced by embedding nano-sized particles in polymeric matrices, are a new class of materials. These materials have attracted world-wide attention due to their superior mechanical, electrical, thermal and barrier properties as well as their outstanding microstructures over the conventional composites. A variety of nanofillers have been produced and used in fabricating polymer nanocomposites over the past two decades. Graphene nanoplatelets (GNPs) are a new type of carbonous nanofiller with extraordinary physical properties, which can be used for reinforcing polymers and developing novel materials with multifunctional properties such as electrical conductivity. GNP-based polymeric nanocomposites can be used in different areas including electrostatic discharge protection, lightening-protection panels, and electromagnetic interference shielding (EMI) applications. The focus of this research is on the development of electrically conductive biodegradable nanocomposites with EMI shielding application. For this purpose, two biodegradable polymers, poly (lactic acid) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT), were chosen as the polymeric matrices, and GNP was used as the conductive nanofiller. PLA/GNP and PBAT/GNP nanocomposites with 0-15 wt% GNPs were produced and characterised via different techniques and the properties of the two systems were systematically analysed and compared. While the glass and melting temperatures of the matrices did not vary considerably with GNP incorporation, their crystallisation temperatures exhibited significant increase. Furthermore, their crystallinity was affected. In particular, crystallinity of PLA was enhanced significantly. Different trends were detected in variations of the Young's moduli of the two polymers with GNP loading; Modulus of PBAT increased continuously with increasing GNP content to 15 wt% while modulus of PLA reached a maximum at 9 wt% GNPs. Thermal stability of the nanocomposites was extensively studied by thermogravimetric analysis under both air and nitrogen atmospheres and at different heating rates. Results showed that GNP embedding enhanced thermal stability of the polymers effectively. In particular, PLA thermal degradation was significantly delayed in the presence of the platelets. While magnetic permeability of the polymers was not affected by GNP incorporation, their electrical properties were significantly enhanced. Dielectric constants of PLA and PBAT increased with increasing GNPs, obtaining comparable values for the same GNP content. On the other hand, dielectric loss of PLA nanocomposites with 9–15 wt% GNPs was markedly higher than that of PBAT nanocomposites. Sihvola's unified mixing rule of complex permittivity was used to model the behaviour of dielectric constants and losses of GNP-based nanocomposites for the first time. As the GNP concentration increased from 6 to 9 wt% (3.5 to 5.3 vol%), an abrupt increase was detected in both AC and DC conductivities of PLA and PBAT, indicating the formation of conductive pathways of GNPs within the matrices. At 15 wt% GNPs, AC conductivities of 7.4 and 3 S/m were obtained for PLA and PBAT nanocomposites respectively despite the higher conductivity of pure PBAT compared to that of pure PLA. This difference was attributed to the better dispersion of GNPs in PBAT, also observed in SEM images. Relatively poor dispersion of GNPs in PLA appeared to facilitate their physical contacts, leading to higher conductivity. EMI shielding effectiveness (SET) of the nanocomposites as well as contributions of reflection and absorption mechanisms to their radiation attenuation were extensively investigated. Enhancement of the electrical properties of PLA and PBAT with GNP embedding resulted in higher SET. For samples with a thickness of 1 mm, SET of PLA and PBAT increased with increasing GNP concentration. PLA and PBAT nanocomposites showed comparable values of SET with reflection being the primary shielding mechanism. However, they exhibited considerably different potentials for radiation absorption due to their different dielectric loss values. Evaluation of shielding performance of the nanocomposites with other thicknesses (1.5 and 2.8 mm) demonstrated that their performance was a function of thickness and radiation frequency in addition to the GNP concentration. It was observed that a greater thickness might not necessarily lead to higher SET and therefore, in designing a nanocomposite for EMI shielding application, material's electromagnetic properties and thickness should be chosen based on the radiation frequency. Another significant part of the present project is its contribution to the knowledge on rheology of GNP-based nanocomposites. Variations of the viscoelastic properties of PLA/GNP and PBAT/GNP nanocomposites, obtained from frequency sweeps, were investigated under simultaneous effects of GNP loading and temperature for the first time. Although it is well-known that temperature can affect microstructure of the materials and consequently alter their viscoelastic properties, the rheological measurements of GNP-based nanocomposites in previous studies have been performed at one single temperature so far. GNP embedding resulted in significant increments in the viscoelastic properties of PLA and PBAT. Solid-like flow behaviour was observed for highly-filled samples while pure polymers and nanocomposites with low GNP loadings showed liquid-like behaviour. However, changing the measurement temperature revealed that rheological percolation threshold of GNPs in these nanocomposites is temperature sensitive. Winter-Chambon gelation criterion was used to determine the percolation threshold in the two systems at different temperatures. The percolation threshold in PLA was found to drop from 8.5 wt% at 180 °C to 5.2 wt% at 220 °C. Similarly, PBAT/GNP nanocomposites exhibited a decreasing trend in percolation threshold from 11.5 wt% at 160 °C to 7 wt% at 220 °C. Furthermore, in contrast to the ideal melts, viscoelastic properties of some of the PLA/GNP and PBAT/GNP nanocomposites increased with increasing temperature. In contrast to the dynamic rheological properties, shear viscosity of all PBAT/GNP nanocomposites decreased with increasing temperature. Temperature dependency of the nanocomposites' shear viscosity was described by Arrhenius equation. The flow activation energy (Ea) was found to decrease with increasing GNPs at low shear rates. Consequently, temperature sensitivity of nanocomposites' viscosity decreased with increasing GNPs. Many previous studies reported an increasing trend in Ea with increasing filler loading. Detailed analysis of these works showed that Ea calculations in these studies were carried out at high shear rates while Ea in the present study was determined in the non-shear-thinning region where the original structure of the nanocomposites is not significantly disturbed

Retrograde intrarenal surgery versus shock wave lithotripsy for renal stones smaller than 2 cm: A randomized clinical trial

Purpose: To compare outcomes of retrograde intrarenal surgery (RIRS) with extracorporeal shock wave lithotripsy (SWL) for stones � 2 cm. Materials and Methods: Patients who were diagnosed with kidney stones of � 2 cm underwent RIRS or SWL in a parallel group randomized clinical trial with balanced randomization 1:1 from 2011 to 2014. The primary outcome of interest was stone free rate after a single session intervention. Patients were evaluated by ultrasonography and KUB at 1 and 3 months after the intervention for the presence of residual stone by a radiologist who was blinded to the study. Results: The stone free rate one month after a single session intervention in the RIRS group was higher than the SWL group (90% versus 75%, P = .03). The success rates after two sessions of RIRS versus SWL were 96.7% versus 88.3% respectively. (P = .08) Patients in the RIRS group had significantly lower postoperative visual analogue pain score compared to the SWL group (5.2 ± 2.8 versus 3.1 ± 2.7, P < .001). Steinstrasse formation and renal hematoma were observed in 4 and one patient in the SWL group versus no patient in the RIRS group. Postoperative hospital stay was significantly shorter in the SWL group (6.7 ± 1.3 versus18.9 ± 4.3 hours, P < .001). Conclusion: The RIRS procedure is a safe treatment option for renal stones of �2cm with less pain and higher success rate at first session compared to SWL