BackgroundIn Vietnam, malaria remains a problem in some remote areas located along its international borders and in the central highlands, partly due to the bionomics of the local vector, mainly found in forested areas and less vulnerable to standard control measures. Long Lasting Insecticidal Hammocks (LLIH), a tailored and user-friendly tool for forest workers, may further contribute in reducing the malaria burden. Their effectiveness was tested in a large community-based intervention trial carried out in Ninh Thuan province in Central Vietnam.Methods and FindingsThirty villages (population 18,646) were assembled in 20 clusters (1,000 individuals per cluster) that were randomly allocated to either the intervention or control group (no LLIH) after stratification according to the pre-intervention P. falciparum antibody prevalence (<30%; ≥30%). LLIH were distributed to the intervention group in December 2004. For the following 2 years, the incidence of clinical malaria and the prevalence of infection were determined by passive case detection at community level and by bi-annual malariometric surveys. A 2-fold larger effect on malaria incidence in the intervention as compared to the control group was observed. Similarly, malaria prevalence decreased more substantially in the intervention (1.6-fold greater reduction) than in the control group. Both for incidence and prevalence, a stronger and earlier effect of the intervention was observed in the high endemicity stratum. The number of malaria cases and infections averted by the intervention overall was estimated at 10.5 per 1,000 persons and 5.6/100 individuals, respectively, for the last half of 2006. In the high endemicity stratum, the impact was much higher, i.e. 29/1000 malaria cases and 15.7 infections/100 individuals averted.ConclusionsLLIH reduced malaria incidence and prevalence in this remote and forested area of Central Vietnam. As the targets of the newly-launched Global Malaria Action Plan include the 75% reduction of the global malaria cases by 2015 and eventually the elimination/eradication of malaria in the long term, LLIH may represent an additional tool for reaching such objectives, particularly in high endemicity areas where standard control tools have a modest impact, such as in remote and forested areas of Southeast Asia and possibly South America.Trial RegistrationClinicalTrials.gov NCT00853281

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Structural evolution and stability pattern of pure neutral gold clusters Au n in the small size range of n = 20–30 are examined using density functional theory (DFT) calculations. The equilibrium geometries are either confirmed or determined, and some new ground state structures are identified. The most stable configurations of Au21–Au23 sizes are formed by adding extra gold atoms to the highly stable pyramidal structure of Au20, while flat-cage shapes are the best candidates for the global minima of both Au24 and Au25. For larger sizes of n = 26–30, pyramidal motifs tend to dominate the lower-lying population rather than tubular conformations as previously reported. The energy gaps, excitation energies, and exciton binding energies are also computed to test out the performance of the computational methods employed. Accordingly, a density functional with long-range exchange effects is highly recommended to quantitatively investigate both the ground and excited states of pure gold clusters.

Density functional theory methods were employed to clarify the adsorption/desorption behaviors of the thione‐containing mercaptopurine and thioguanine drugs on the gold surface using both small Au6 and Au8 clusters as model reactants. Structural features, thermodynamic parameters, bonding characteristics, and electronic properties of the resulting complexes were investigated using the Perdew–Burke–Ernzerhof (PBE) and LC‐BLYP functionals along with correlation‐consistent basis sets, namely cc‐pVDZ‐PP for gold and cc‐pVTZ for non‐metals. Computed results show that the drug molecules tend to anchor on the gold cluster at the S atom with binding energies around −34 to −40 kcal/mol (in vacuum) and − 28 to −32 kcal/mol (in aqueous solution). As compared to Au8, Au6 undergoes a shorter recovery time and a larger change of energy gap that could be converted to an electrical signal for selective detection of the drugs. Furthermore, interactions between the drugs and gold clusters are reversible processes and a drug release mechanism was also proposed. Accordingly, the drugs are able to separate from the gold surface due to either a slight change of pH in tumor cells or the presence of cysteine residues in protein matrices.