Large scale quantum simulations: C_60 impacts on a semiconducting surface

We present tight binding molecular dynamics simulations of C_60 collisions on the reconstructed diamond(111) surface, carried out with an O(N) method and with cells containing 1140 atoms. The results of our simulations are in very good agreement with experiments performed under the same impact conditions. Furthermore our calculations provide a detailed characterization of the microscopic processes occuring during the collision, and allow the identification of three impact regimes, as a function of the fullerene incident energy. Finally, the study of the reactivity between the cluster and the surface gives insight into the deposition mechanisms of C_60 on semiconducting substrates

Dynamical Jahn-Teller Effect and Berry Phase in Positively Charged Fullerene I. Basic Considerations

We study the Jahn-Teller effect of positive fullerene ions $^2$C$_{60}^{+}$ and $^1$C$_{60}^{2+}$. The aim is to discover if this case, in analogy with the negative ion, possesses a Berry phase or not, and what are the consequences on dynamical Jahn-Teller quantization. Working in the linear and spherical approximation, we find no Berry phase in $^1$C$_{60}^{2+}$, and presence/absence of Berry phase for coupling of one $L=2$ hole to an $L=4$/$L=2$ vibration. We study in particular the special equal-coupling case ($g_2=g_4$), which is reduced to the motion of a particle on a 5-dimensional sphere. In the icosahedral molecule, the final outcome assesses the presence/absence of a Berry phase of $\pi$ for the $h_u$ hole coupled to $G_g$/$H_h$ vibrations. Some qualitative consequences on ground-state symmetry, low-lying excitations, and electron emission from C$_{60}$ are spelled out.Comment: 31 pages (RevTeX), 3 Postscript figures (uuencoded

Discrimination of roast and ground coffee aroma

Background: Four analytical approaches were used to evaluate the aroma profile at key stages in roast and ground coffee brew preparation (concentration within the roast and ground coffee and respective coffee brew; concentration in the headspace of the roast and ground coffee and respective brew). Each method was evaluated by the analysis of 15 diverse key aroma compounds that were predefined by odour port analysis. Results: Different methods offered complimentary results for the discrimination of products; the concentration in the coffee brew was found to be the least discriminatory and concentration in the headspace above the roast and ground coffee was shown to be most discriminatory. Conclusions: All approaches should be taken into consideration when classifying roast and ground coffee especially for alignment to sensory perception and consumer insight data as all offer markedly different discrimination abilities due to the variation in volatility, hydrophobicity, air-water partition coefficient and other physicochemical parameters of the key aroma compounds present

Real-time mass spectrometry monitoring of oak wood toasting: elucidating aroma development relevant to oak-aged wine quality

We introduce a real-time method to monitor the evolution of oak aromas during the oak toasting process. French and American oak wood boards were toasted in an oven at three different temperatures, while the process-gas was continuously transferred to the inlet of a proton-transfer-reaction time-of-flight mass spectrometer for online monitoring. Oak wood aroma compounds important for their sensory contribution to oak-aged wine were tentatively identified based on soft ionization and molecular mass. The time-intensity profiles revealed toasting process dynamics illustrating in real-time how different compounds evolve from the oak wood during toasting. Sufficient sensitivity was achieved to observe spikes in volatile concentrations related to cracking phenomena on the oak wood surface. The polysaccharide-derived compounds exhibited similar profiles; whilst for lignin-derived compounds eugenol formation differed from that of vanillin and guaiacol at lower toasting temperatures. Significant generation of oak lactone from precursors was evident at 225 (o)C. Statistical processing of the real-time aroma data showed similarities and differences between individual oak boards and oak wood sourced from the different origins. This study enriches our understanding of the oak toasting process and demonstrates a new analytical approach for research on wood volatiles

Participation by conflict-affected and forcibly displaced communities in humanitarian healthcare responses: A systematic review.

BACKGROUND: Community participation in health responses in humanitarian crises is increasingly promoted by humanitarian actors to support adoption of measures that are relevant and effective to local needs. Our aim was to understand the role of community participation in humanitarian health responses for conflict-affected populations (including forcibly displaced populations) in low- and middle-income countries and the barriers and facilitators to community participation in healthcare responses. METHODS: Using a systematic review methodology, following the PRISMA protocol, we searched four bibliographic databases for publications reporting peer-reviewed primary research. Studies were selected if they reported how conflict-affected populations were involved in healthcare responses in low- and middle-income settings, and associated changes in healthcare responses or health outcomes. We applied descriptive thematic synthesis and assessed study quality using study design-specific appraisal tools. RESULTS: Of 18,247 records identified through the database searching, 18 studies met our inclusion criteria. Various types of community participation were observed, with participation mostly involved in implementing interventions rather than framing problems or designing solutions. Most studies on community participation focused on changes in health services (access, utilisation, quality), community acceptability and awareness, and ownership and sustainability. Key barriers and facilitators to community participation included political will at national and local level, ongoing armed conflict, financial and economic factors, socio-cultural dynamics of communities, design of humanitarian responses, health system factors, and health knowledge and beliefs. Included studies were of mixed quality and the overall strength of evidence was weak. More generally there was limited critical engagement with concepts of participation. CONCLUSION: This review highlights the need for more research on more meaningful community participation in healthcare responses in conflict-affected communities, particularly in framing problems and creating solutions. More robust research is also required linking community participation with longer-term individual and health system outcomes, and that critically engages in constructs of community participation

Large Scale Association Analysis Identifies Three Susceptibility Loci for Coronary Artery Disease

Genome wide association studies (GWAS) and their replications that have associated DNA variants with myocardial infarction (MI) and/or coronary artery disease (CAD) are predominantly based on populations of European or Eastern Asian descent. Replication of the most significantly associated polymorphisms in multiple populations with distinctive genetic backgrounds and lifestyles is crucial to the understanding of the pathophysiology of a multifactorial disease like CAD. We have used our Lebanese cohort to perform a replication study of nine previously identified CAD/MI susceptibility loci (LTA, CDKN2A-CDKN2B, CELSR2-PSRC1-SORT1, CXCL12, MTHFD1L, WDR12, PCSK9, SH2B3, and SLC22A3), and 88 genes in related phenotypes. The study was conducted on 2,002 patients with detailed demographic, clinical characteristics, and cardiac catheterization results. One marker, rs6922269, in MTHFD1L was significantly protective against MI (OR = 0.68, p = 0.0035), while the variant rs4977574 in CDKN2A-CDKN2B was significantly associated with MI (OR = 1.33, p = 0.0086). Associations were detected after adjustment for family history of CAD, gender, hypertension, hyperlipidemia, diabetes, and smoking. The parallel study of 88 previously published genes in related phenotypes encompassed 20,225 markers, three quarters of which with imputed genotypes The study was based on our genome-wide genotype data set, with imputation across the whole genome to HapMap II release 22 using HapMap CEU population as a reference. Analysis was conducted on both the genotyped and imputed variants in the 88 regions covering selected genes. This approach replicated HNRNPA3P1-CXCL12 association with CAD and identified new significant associations of CDKAL1, ST6GAL1, and PTPRD with CAD. Our study provides evidence for the importance of the multifactorial aspect of CAD/MI and describes genes predisposing to their etiology

Insight into the time-resolved extraction of aroma compounds during espresso coffee preparation: Online monitoring by PTR-ToF-MS.

Using proton-transfer-reaction time-of-flight mass-spectrometry (PTR-ToF-MS), we investigated the extraction dynamic of 95 ion traces in real time (time resolution: 1 second) during espresso coffee preparation. Fifty-two of these ions were tentatively identified. This was achieved by on-line sampling of the volatile organic compounds (VOCs) in close vicinity to the coffee flow, at the exit of the extraction hose of the espresso machine (single serve capsules). Ten replicates of six different single serve coffee types were extracted to a final volume of between 30 - 110 mL, according to the recommended cup size of the respective coffee capsule (Ristretto, Espresso and Lungo), and analyzed. The results revealed considerable differences in the extraction kinetics between compounds, which led to a fast evolution of the volatile profiles in the extract flow and consequently to an evolution of the final aroma balance in the cup. Besides exploring the time-resolved extraction dynamics of VOCs, the dynamic data also allowed the coffees types (capsules) to be distinguished from one another. Both Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) showed full separation between the coffees types. The methodology developed provides a fast and simple means of studying the extraction dynamics of VOCs and differentiating between different coffee types