Search

The increasing importance of Laser Sintering (LS) for the industry brings a rising number of available materials for this process. One example is the enhanced use of alternative polyamide types like polyamide 6 (PA 6). For polyamide 12 (PA 12), the powder ageing effect is well-known and of great importance from an economical point of view. However, relatively little is known about the powder ageing behavior of newer LS materials. Hence this paper focuses on the experimental powder ageing study of PA 6 in the LS process, both on powder and part level. The powder was reused in total seven times without refreshing and constant sinter parameters were used to produce the samples. Morphological, thermal and rheological measurements of the powder showed a rising number of agglomerates, an apparent increase in the powder crystallinity, and an increase in the viscosity by a factor of 7. These increases consequently affected the density and the mechanical properties of the parts, latter were determined by tensile tests. Between the first and the last iteration, a decrease of the Young’s Modulus of 60 % and the tensile strength of 70 % was observed. Besides the decline of mechanical properties, the geometrical dimensions of the last iteration were only 60 % of the first iteration, the mass was halved and the surface quality suffered from the orange peel effect. The results prove that similar powder ageing effects known for PA 12, and here especially the polyamide post condensation, also take place in LS printing of PA 6.

Islet transplantation is a promising therapy used to achieve glycometabolic control in a select subgroup of individuals with type I diabetes. However, features that characterize human islet isolation success prior to transplantation are not standardized and lack validation. We conducted a retrospective analysis of 806 isolation records from 14 pancreas‐processing laboratories, considering variables from relevant studies in the last 15 years. The outcome was defined as postpurification islet equivalent count, dichotomized into yields ≥315 000 or ≤220 000. Univariate analysis showed that donor cause of death and use of hormonal medications negatively influenced outcome. Conversely, pancreata from heavier donors and those containing elevated levels of surface fat positively influence outcome, as did heavier pancreata and donors with normal amylase levels. Multivariable logistic regression analysis identified the positive impact on outcome of surgically intact pancreata and donors with normal liver function, and confirmed that younger donors, increased body mass index, shorter cold ischemia times, no administration of fluid/electrolyte medications, absence of organ edema, use of University of Wisconsin preservation solution and a fatty pancreas improves outcome. In conclusion, this multicenter analysis highlights the importance of carefully reviewing all donor, pancreas and processing parameters prior to isolation and transplantation.

Islet transplantation is a promising therapy used to achieve glycometabolic control in a select subgroup of individuals with type I diabetes. However, features that characterize human islet isolation success prior to transplantation are not standardized and lack validation. We conducted a retrospective analysis of 806 isolation records from 14 pancreas-processing laboratories, considering variables from relevant studies in the last 15 years. The outcome was defined as postpurification islet equivalent count, dichotomized into yields ?315?000 or ?220?000. Univariate analysis showed that donor cause of death and use of hormonal medications negatively influenced outcome. Conversely, pancreata from heavier donors and those containing elevated levels of surface fat positively influence outcome, as did heavier pancreata and donors with normal amylase levels. Multivariable logistic regression analysis identified the positive impact on outcome of surgically intact pancreata and donors with normal liver function, and confirmed that younger donors, increased body mass index, shorter cold ischemia times, no administration of fluidelectrolyte medications, absence of organ edema, use of University of Wisconsin preservation solution and a fatty pancreas improves outcome. In conclusion, this multicenter analysis highlights the importance of carefully reviewing all donor, pancreas and processing parameters prior to isolation and transplantation.

I order to study the time-course of myeloperoxidase (MPO) and eosinophil cationic protein (ECP) as parameters for monitoring inflammation in cystic fibrosis (CF), we investigated ten patients during both a 14-day intravenous antibiotic treatment and a corresponding self control. Modified Shwachman-Kulczycki score improved significantly (p < 0.008), C-reactive protein (CRP) levels decreased significantly (p < 0.05) during antibiotic treatment, while in the control phase there were no significant differences. Lung function parameters did not change significantly during antibiotic treatment or control phase. Serum MPO concentration (p < 0.006) and peripheral blood neutrophil granulocyte counts (p < 0.04) decreased significantly during antibiotic treatment, but not during the control phase. Sentm ECP concentration showed a tendency to decrease during antibiotic treatment, but this failed to reach significance. In general, sputum concentrations of MPO and ECP Were 500- to 1000-fold higher than in serum. However, neither MPO nor ECP in sputum showed a significan variation over time during antibiotic treatment or control phase. From our data we conclude that: (1) measurements of MPO, neutrophils and CRP in peripheral blood do correlate with clinical parameters such as the modified Shwachman-Kulczycki score; (2) neutrophils and MPO seem to reflect inflammatory changes induced by antibiotic treatment; (3) eosinophils may play a role in CF by an enhanced ‘releasability’ and (4) Sputum measurements of mediators of inflammation cannot be recommended.

Previous work has shown that queen honeybees,Apis mellifera, produce waxy esters composed of 8–14 carbon acids and 6–14 carbon alcohols in their feces. We tested these esters for effects on nestmate recognition; 11 of the 12 esters tested significantly modified the recognition characteristics of worker honeybees. Pairwise tests showed that workers can discriminate between at least some pairs of queen esters and that workers can discriminate between a queen ester and hexadecane (another known nestmate recognition cue). These results suggest that a queen may use the esters to enable workers to recognize her or to scent-mark her colony.

I order to study the time-course of myeloperoxidase (MPO) and eosinophil cationic protein (ECP) as parameters for monitoring inflammation in cystic fibrosis (CF), we investigated ten patients during both a 14-day intravenous antibiotic treatment and a corresponding self control. Modified Shwachman-Kulczycki score improved significantly (p < 0.008), C-reactive protein (CRP) levels decreased significantly (p < 0.05) during antibiotic treatment, while in the control phase there were no significant differences. Lung function parameters did not change significantly during antibiotic treatment or control phase. Serum MPO concentration (p < 0.006) and peripheral blood neutrophil granulocyte counts (p < 0.04) decreased significantly during antibiotic treatment, but not during the control phase. Sentm ECP concentration showed a tendency to decrease during antibiotic treatment, but this failed to reach significance. In general, sputum concentrations of MPO and ECP Were 500- to 1000-fold higher than in serum. However, neither MPO nor ECP in sputum showed a significan variation over time during antibiotic treatment or control phase. From our data we conclude that: (1) measurements of MPO, neutrophils and CRP in peripheral blood do correlate with clinical parameters such as the modified Shwachman-Kulczycki score; (2) neutrophils and MPO seem to reflect inflammatory changes induced by antibiotic treatment; (3) eosinophils may play a role in CF by an enhanced ‘releasability’ and (4) Sputum measurements of mediators of inflammation cannot be recommended.