Low-Viscosity Route to High-Molecular-Weight Water-Soluble Polymers: Exploiting the Salt Sensitivity of Poly(N-acryloylmorpholine).

We report a new one-pot low-viscosity synthetic route to high molecular weight non-ionic water-soluble polymers based on polymerization-induced self-assembly (PISA). The RAFT aqueous dispersion polymerization of N-acryloylmorpholine (NAM) is conducted at 30 °C using a suitable redox initiator and a poly(2-hydroxyethyl acrylamide) (PHEAC) precursor in the presence of 0.60 M ammonium sulfate. This relatively low level of added electrolyte is sufficient to salt out the PNAM block, while steric stabilization is conferred by the relatively short salt-tolerant PHEAC block. A mean degree of polymerization (DP) of up to 6000 was targeted for the PNAM block, and high NAM conversions (>96%) were obtained in all cases. On dilution with deionized water, the as-synthesized sterically stabilized particles undergo dissociation to afford molecularly dissolved chains, as judged by dynamic light scattering and 1H NMR spectroscopy studies. DMF GPC analysis confirmed a high chain extension efficiency for the PHEAC precursor, but relatively broad molecular weight distributions were observed for the PHEAC-PNAM diblock copolymer chains (Mw/Mn > 1.9). This has been observed for many other PISA formulations when targeting high core-forming block DPs and is tentatively attributed to chain transfer to polymer, which is well known for polyacrylamide-based polymers. In fact, relatively high dispersities are actually desirable if such copolymers are to be used as viscosity modifiers because solution viscosity correlates closely with Mw. Static light scattering studies were also conducted, with a Zimm plot indicating an absolute Mw of approximately 2.5 × 106 g mol-1 when targeting a PNAM DP of 6000. Finally, it is emphasized that targeting such high DPs leads to a sulfur content for this latter formulation of just 23 ppm, which minimizes the cost, color, and malodor associated with the organosulfur RAFT agent.

Engineering Biocatalytic Solar Fuel Production: The PHOTOFUEL Consortium.

The EU Horizon2020 consortium PHOTOFUEL joined academic and industrial partners from biology, chemistry, engineering, engine design, and lifecycle assessment, making tremendous progress towards engine-ready fuels from CO2 via engineered photosynthetic microbes. Technical, environmental, economic, and societal opportunities and challenges were explored to frame future technology realization at scale.

Single-step dynamic dewatering of microalgae from dilute suspensions using flocculant assisted filtration.

BACKGROUND: Dewatering constitutes a major challenge to the production of microalgae, accounting for 20-30% of the product cost. This presents a setback for the applicability of microalgae in the development of several sustainable products. This study presents an investigation into the dynamic dewatering of microalgae in a combined flocculation-filtration process. The effect of process conditions on the performance of 12 flocculants and their mixtures was assessed. RESULTS: The mechanism of flocculation via the electrostatic path was dominated by charge neutralization and subsequently followed bridging in a 'sweep flocculation' process. Cationic polyacrylamide (CPAM) based flocculants recorded the highest biomass retention with PAM1 and PAM2 attaining 99 and 98% retention with flocculant dosages of 10 and 15 mg/L respectively. Polyvinylamine (PVAM) was also found to improve system stability across the pH range 4-10. Alum was observed to be only effective in charge neutralization, bringing the system close to its isoelectric point (IEP). Chemometric analysis using the multi-criteria decision methods, PROMETHEE and GAIA, was applied to provide a sequential performance ranking based on the net outranking flow (ф) from 207 observations. A graphical exploration of the flocculant performance pattern, grouping the observations into clusters in relation to the decision axis ([Formula: see text]), which indicated the weighted resultant of most favorable performance for all criteria was explored. CONCLUSION: CPAM based flocculants and their mixtures demonstrated superior performance due to their viscoelastic behaviour under turbulence. The use of PVAM or alum in mixtures with CPAM reduced the required doses of both flocculants, which will provide beneficial financial impact for largescale microalgae dewatering in a flocculant assisted dynamic filtration process. Chemometric analysis based on the physico-chemical properties of the system provides a time saving assessment of performance across several criteria. The study findings provide an important foundation for flocculant assisted dynamic filtration processes.

Driving and restraining forces for the implementation of the Agrophotovoltaics system technology - A system dynamics analysis.

The innovative Agrophotovoltaics (APV) system technology combines agricultural biomass and solar power production on the same site and aims at reducing the conflict between food and power production. Unrelated to this benefit, this technology may impact the landscape negatively and could thus be subject to public opposition and/or restraining frameworks. The presented study offers a System Dynamics (SD) approach, through Causal Loop Diagrams (CLDs) models, based on the results of citizen workshops, literature research, and expert discussions on the technology. A comprehensive analysis of the driving and restraining forces for the implementation of APV-technology and expected or potential impacts reveals influential factors. Hence, this SD approach identifies bottlenecks and conflicting objectives in the technology implementation that need to be further addressed. A key finding is that successful APV-projects would require stakeholder involvement to achieve greater local acceptance. When it comes to production on agricultural land, APV-systems may drive the land use efficiency to up to 186 percent when the PV-panels serve for protection against heat stress. On the other hand, altered precipitation patterns and impacts on agricultural cultivation and, especially, the landscape caused by the technical system, may restrain the application of APV. Finally, system design factors and operator modes are amongst the criteria that may influence the local acceptance in society, farmers' motivation for APV and economic factors for the market launch of APV.

Acceptability of genetically engineered algae biofuels in Europe: opinions of experts and stakeholders.

BACKGROUND: The development of alternative pathways for sustainable fuel production is a crucial task for politics, industry and research, since the current use of fossil fuels contributes to resource depletion and climate change. Microalgae are a promising option, but the technology readiness level (TRL) is low and cannot compete economically with fossil fuels. Novel genetic engineering technologies are being investigated to improve productivity and reduce the cost of harvesting products extracted from or excreted by microalgae for fuel production. However, high resource efficiency and low costs alone are no guarantee that algae fuels will find their way into the market. Technologies must be accepted by the public to become valuable for society. Despite strong efforts in algae research and development, as well as political commitments at different scales to promote algae biofuels for transport sectors, little is known about public acceptance of this alternative transport fuel. Despite the advantages of algae technology, genetically engineered (GE) microalgae can be controversial in Europe due to risk perception. Therefore, the aim of this study was to investigate, for the first time, the knowledge and views of European experts and stakeholders on the conditions and requirements for acceptability of GE microalgae for next generation biofuel production. RESULTS: The results of the survey-based study indicate that the majority of the respondents believe that GE algae biofuels could provide strong benefits compared to other fuels. The majority would choose to be final consumers of engineered algae biofuels, if there is clear evidence of their benefits and open communication of potential risks. They believe that closed production systems with high security standards and rigorous risk assessment should be applied to avoid unintended impacts on humans and nature. Some respondents, however, are not convinced about the need to alter natural occurring algae strains to increase productivity, arguing that there is a huge unexplored variety, and that the consequences of using genome editing are still unknown. CONCLUSIONS: This evaluation of the opinions held by European experts and stakeholders regarding GE algae biofuels provides valuable and differentiated insights, both for future research and for the development of feasible socio-technical algae systems for next generation biofuel production. The identified conditions and requirements for achieving public acceptability can support the (re-)design of this innovative technology and adaptation of the framework conditions towards the implementation of algae biofuels in Europe.

Factors Affecting Microalgae Production for Biofuels and the Potentials of Chemometric Methods in Assessing and Optimizing Productivity.

Microalgae are swift replicating photosynthetic microorganisms with several applications for food, chemicals, medicine and fuel. Microalgae have been identified to be suitable for biofuels production, due to their high lipid contents. Microalgae-based biofuels have the potential to meet the increasing energy demands and reduce greenhouse gas (GHG) emissions. However, the present state of technology does not economically support sustainable large-scale production. The biofuel production process comprises the upstream and downstream processing phases, with several uncertainties involved. This review examines the various production and processing stages, and considers the use of chemometric methods in identifying and understanding relationships from measured study parameters via statistical methods, across microalgae production stages. This approach enables collection of relevant information for system performance assessment. The principal benefit of such analysis is the identification of the key contributing factors, useful for decision makers to improve system design, operation and process economics. Chemometrics proffers options for time saving in data analysis, as well as efficient process optimization, which could be relevant for the continuous growth of the microalgae industry.

Influence of bacterial N-acyl-homoserine lactones on growth parameters, pigments, antioxidative capacities and the xenobiotic phase II detoxification enzymes in barley and yam bean.

Bacteria are able to communicate with each other and sense their environment in a population density dependent mechanism known as quorum sensing (QS). N-acyl-homoserine lactones (AHLs) are the QS signaling compounds of Gram-negative bacteria which are frequent colonizers of rhizospheres. While cross-kingdom signaling and AHL-dependent gene expression in plants has been confirmed, the responses of enzyme activities in the eukaryotic host upon AHLs are unknown. Since AHL are thought to be used as so-called plant boosters or strengthening agents, which might change their resistance toward radiation and/or xenobiotic stress, we have examined the plants' pigment status and their antioxidative and detoxifying capacities upon AHL treatment. Because the yield of a crop plant should not be negatively influenced, we have also checked for growth and root parameters. We investigated the influence of three different AHLs, namely N-hexanoyl- (C6-HSL), N-octanoyl- (C8-HSL), and N-decanoyl- homoserine lactone (C10-HSL) on two agricultural crop plants. The AHL-effects on Hordeum vulgare (L.) as an example of a monocotyledonous crop and on the tropical leguminous crop plant Pachyrhizus erosus (L.) were compared. While plant growth and pigment contents in both plants showed only small responses to the applied AHLs, AHL treatment triggered tissue- and compound-specific changes in the activity of important detoxification enzymes. The activity of dehydroascorbate reductase in barley shoots after C10-HSL treatment for instance increased up to 384% of control plant levels, whereas superoxide dismutase activity in barley roots was decreased down to 23% of control levels upon C6-HSL treatment. Other detoxification enzymes reacted similarly within this range, with interesting clusters of positive or negative answers toward AHL treatment. In general the changes on the enzyme level were more severe in barley than in yam bean which might be due to the different abilities of the plants to degrade AHLs to metabolites such as the hydroxy- or keto-form of the original compound.

Characterization of Skin Aging-Associated Secreted Proteins (SAASP) Produced by Dermal Fibroblasts Isolated from Intrinsically Aged Human Skin.

Most molecular hallmarks of cellular senescence have been identified in studies of cells aged in vitro by driving them into replicative or stress-induced senescence. Comparatively, less is known about the characteristic features of cells that have aged in vivo. Here we provide a systematic molecular analysis of normal human dermal fibroblasts (NHDFs) that were isolated from intrinsically aged human skin of young versus middle aged versus old donors. Intrinsically aged NHDFs in culture exhibited more frequently nuclear foci positive for p53 binding protein 1 and promyelocytic leukemia protein reminiscent of 'DNA segments with chromatin alterations reinforcing senescence (DNA-SCARS)'. Formation of such foci was neither accompanied by increased DNA double strand breaks, nor decreased cell viability, nor telomere shortening. However, it was associated with the development of a secretory phenotype, indicating incipient cell senescence. By quantitative analysis of the entire secretome present in conditioned cell culture supernatant, combined with a multiplex cytokine determination, we identified 998 proteins secreted by intrinsically aged NHDFs in culture. Seventy of these proteins exhibited an age-dependent secretion pattern and were accordingly denoted 'skin aging-associated secreted proteins (SAASP)'. Systematic comparison of SAASP with the classical senescence-associated secretory phenotype (SASP) revealed that matrix degradation as well as proinflammatory processes are common aspects of both conditions. However, secretion of 27 proteins involved in the biological processes of 'metabolism' and 'adherens junction interactions' was unique for NHDFs isolated from intrinsically aged skin. In conclusion, fibroblasts isolated from intrinsically aged skin exhibit some, but not all, molecular hallmarks of cellular senescence. Most importantly, they secrete a unique pattern of proteins that is distinct from the canonical SASP and might reflect specific processes of skin aging.

Inadequate mito-biogenesis in primary dermal fibroblasts from old humans is associated with impairment of PGC1A-independent stimulation.

Extrinsic skin ageing converges on the dermis, a post-mitotic tissue compartment consisting of extracellular matrix and long-lived fibroblasts prone to damage accumulation and maladaptation. Aged human fibroblasts exhibit mitochondrial and nuclear dysfunctions, which may be a cause or consequence of ageing. We report on a systematic study of human dermal fibroblasts retrieved from female donors aged 20-67 years and analysed ex vivo at low population doubling precluding replicative senescence. According to gene set enrichment analysis of genome wide array data, the most prominent age-associated change of the transcriptome was decreased expression of mitochondrial genes. Consistent with that, mitochondrial content and cell proliferation declined with donor age. This was associated with upregulation of AMP-dependent protein kinase (AMPK), increased mRNA levels of PPARγ-coactivator 1α (PGC1A) and decreased levels of NAD(+)-dependent deacetylase sirtuin 1. In the old cells the PGC1A-mediated mito-biogenetic response to direct AMPK-stimulation by AICAR was undiminished, while the PGC1A-independent mito-biogenetic response to starvation was attenuated and accompanied by increased ROS-production. In summary, these observations suggest an age-associated decline in PGC1A-independent mito-biogenesis, which is insufficiently compensated by upregulation of the AMPK/PGC1A-axis leading under baseline conditions to decreased mitochondrial content and reductive overload of residual respiratory capacity.

Materials flow modeling of nutrient recycling in biodiesel production from microalgae.

Biodiesel production based on microalgae as feedstock is associated with a high demand of nutrients, respectively nitrogen and phosphorus. The production of 1l biodiesel requires between 0.23 and 1.55 kg nitrogen and 29-145 g of phosphorus depending of the cultivation conditions for microalgae. The supply of nutrients can be expected to severely limit the extent to which the production of biofuels from microalgae can be sustainably expanded. The nutrient demand can be reduced if the nutrients in the residual algae biomass after oil extraction are reused for algae cultivation. This modeling work illustrates that for the investigated process chains and scenarios the nutrient recycling rates are in the range from 30% to 90% for nitrogen and from 48% to 93% for phosphorus. The highest recycling values can be achieved by hydrothermal gasification of the oil-free residues.

Preventing neural tube defects in Europe: a missed opportunity.

Each year, more than 4500 pregnancies in the European Union are affected by neural tube defects (NTD). Unambiguous evidence of the effectiveness of periconceptional folic acid in preventing the majority of neural tube defects has been available since 1991. We report on trends in the total prevalence of neural tube defects up to 2002, in the context of a survey in 18 European countries of periconceptional folic acid supplementation (PFAS) policies and their implementation. EUROCAT is a network of population-based registries in Europe collaborating in the epidemiological surveillance of congenital anomalies. Representatives from 18 participating countries provided information about policy, health education campaigns and surveys of PFAS uptake. The yearly total prevalence of neural tube defects including livebirths, stillbirths and terminations of pregnancy was calculated from 1980 to 2002 for 34 registries, with UK and Ireland estimated separately from the rest of Europe. A meta-analysis of changes in NTD total prevalence between 1989-1991 and 2000-2002 according to PFAS policy was undertaken for 24 registries. By 2005, 13 countries had a government recommendation that women planning a pregnancy should take 0.4mg folic acid supplement daily, accompanied in 7 countries by government-led health education initiatives. In the UK and Ireland, countries with PFAS policy, there was a 30% decline in NTD total prevalence (95% CI 16-42%) but it was difficult to distinguish this from the pre-existing strong decline. In other European countries with PFAS policy, there was virtually no decline in NTD total prevalence whether a policy was in place by 1999 (2%, 95% CI 28% reduction to 32% increase) or not (8%, 95% CI 26% reduction to 16% increase). The potential for preventing NTDs by periconceptional folic acid supplementation is still far from being fulfilled in Europe. Only a public health policy including folic acid fortification of staple foods is likely to result in large-scale prevention of NTDs.

Pregnancy course and outcome after intracytoplasmic sperm injection: a controlled, prospective cohort study.

OBJECTIVE: To determine pregnancy course and major malformation rate after intracytoplasmic sperm injection (ICSI). DESIGN: Prospective, controlled, multicenter, nationwide German cohort study. SETTING: Tertiary infertility centers in Germany. PATIENT(S): Three thousand three hundred seventy-two children and fetuses and 8,016 children and fetuses after the 16th week of gestation in pregnancies after ICSI and natural conception, respectively. INTERVENTION(S): Standardized prospective follow-up. MAIN OUTCOME MEASURE(S): Major malformation rate. RESULT(S): The major malformation rate was 8.7% (295/3,372) for the ICSI cohort and 6.1% (488/8,016) for the population-based control cohort (relative risk, 1.44 [1.25-1.65]). After adjustment for risk factors, the risk declined (adjusted odds ratio, 1.24 [95% CI, 1.02-1.50]). Regarding singletons, there was a significant difference for birth weight and gestational age, with a higher number of preterm and low birth weight children in pregnancies achieved after ICSI. CONCLUSION(S): Children who are born after intracytoplasmic sperm injection have an increased risk of a major congenital malformation compared with those born after spontaneous conception. This risk is mainly due to paternal and maternal risk factors, which are more prevalent in couples who use ICSI for reproduction. An infertility-linked risk is highly probable for the observed findings. A technique-related risk, however, cannot be ruled out.