Intensified food production, i.e. agricultural intensification and industrialized livestock operations may have adverse effects on human health and promote disease emergence via numerous mechanisms ...resulting in either direct impacts on humans or indirect impacts related to animal and environmental health. For example, while biodiversity is intentionally decreased in intensive food production systems, the consequential decrease in resilience in these systems may in turn bear increased health risks. However, quantifying these risks remains challenging, even if individual intensification measures are examined separately. Yet, this is an urgent task, especially in rapidly developing areas of the world with few regulations on intensification measures, such as in the Greater Mekong Subregion (GMS).
We systematically searched the databases PubMed and Scopus for recent studies conducted on the association between agricultural (irrigation, fertilization, pesticide application) and livestock (feed additives, animal crowding) intensification measures and human health risks in the GMS. The search terms used were iteratively modified to maximize the number of retrieved studies with relevant quantitative data.
We found that alarmingly little research has been done in this regard, considering the level of environmental contamination with pesticides, livestock infection with antibiotic resistant pathogens and disease vector proliferation in irrigated agroecosystems reported in the retrieved studies. In addition, each of the studies identified focused on specific aspects of intensified food production and there have been no efforts to consolidate the health risks from the simultaneous exposures to the range of hazardous chemicals utilized.
While some of the studies identified already reported environmental contamination bearing considerable health risks for local people, at the current state of research the actual consolidated risk from regional intensification measures cannot be estimated. Efforts in this area of research need to be rapidly and considerably scaled up, keeping pace with the current level of regional intensification and the speed of pesticide and drug distribution to facilitate the development of agriculture related policies for regional health promotion.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
New requirements for high-frequency applications in wireless communication and sensor technologies need III-V compound semiconductors such as indium phosphide (InP) to complement silicon (Si)-based ...technologies. This study establishes the basis for a new approach to heterogeneous integration of III-V on Si aimed at the transfer of single-crystalline InP coupons on Si via micro-transfer printing (μTP). The InP coupons will act as high-quality virtual substrates that allow selective homo-epitaxy. We present the chemical-mechanical polishing-based preparation and structural characterization of µm-thin (001) InP platelets, starting from high-quality 4-inch bulk crystals and micro-patterning into transferable coupons of several hundred µm2. The obtained InP platelets exhibit the desired thickness—below 10 ± 1 µm—and low surface roughness—<0.3 nm—on both sides, meeting the precondition for µTP and epitaxy. X-ray rocking curve measurements provide accurate spatial maps of the total strain, which indicate small strain variations in the µm-thin InP sample. Rocking curve mappings of the (0 0 4) reflection reveal half-widths below 16 arcsec in the majority of the sample area after thinning that is similar to commercially available InP bulk substrates. Pole figure measurements show no evidence of stress-induced micro-twinning or stacking faults. Overall, minor indications of crystal quality degradation in the product platelets, compared with the bulk samples, were detected.
Multienzyme docking in hybrid megasynthetases Richter, Carsten D; Broadhurst, R William; Weissman, Kira J ...
Nature chemical biology,
01/2008, Letnik:
4, Številka:
1
Journal Article
Recenzirano
Hybrid multienzyme systems composed of polyketide synthase (PKS) and nonribosomal polypeptide synthetase (NRPS) modules direct the biosynthesis of clinically valuable natural products in bacteria. ...The fidelity of this process depends on specific recognition between successive polypeptides in each assembly line-interactions that are mediated by terminal 'docking domains'. We have identified a new family of N-terminal docking domains, exemplified by TubCdd from the tubulysin system of Angiococcus disciformis An d48. TubCdd is homodimeric, which suggests that NRPS subunits in mixed systems self-associate to interact with partner PKS homodimers. The NMR structure of TubCdd reveals a new fold featuring an exposed beta-hairpin that serves as the binding site for the C-terminal docking domain of the partner polypeptide. The pattern of charged residues on the contact surface of the beta-hairpin is a key determinant of the interaction and seems to constitute a 'docking code' that can be used to alter binding affinity.
Ferroelectric materials are used in actuators or sensors because of their non-volatile macroscopic electric polarization. GeTe is the simplest known diatomic ferroelectric endowed with exceedingly ...complex physics related to its crystalline, amorphous, thermoelectric, and—fairly recently discovered—topological properties, making the material potentially interesting for spintronics applications. Typically, ferroelectric materials possess random oriented domains that need poling to achieve macroscopic polarization. By using X-ray absorption fine structure spectroscopy complemented with anomalous diffraction and piezo-response force microscopy, we investigated the bulk ferroelectric structure of GeTe crystals and thin films. Both feature multi-domain structures in the form of oblique domains for films and domain colonies inside crystals. Despite these multi-domain structures which are expected to randomize the polarization direction, our experimental results show that at room temperature there is a preferential ferroelectric order remarkably consistent with theoretical predictions from ideal GeTe crystals. This robust self-poled state has high piezoelectricity and additional poling reveals persistent memory effects.
Subjecting strontium titanate single crystals to an electric field in the order of 106 V m−1 is accompanied by a distortion of the cubic crystal structure, so that inversion symmetry vanishes and a ...polar phase is established. Since the polar nature of the migration-induced field-stabilized polar (MFP) phase is still unclear, the present work investigates and confirms the pyroelectric structure. We present measurements of thermally stimulated and pyroelectric currents that reveal a pyroelectric coefficient pMFP in the order of 30 C K−1m−2. Therefore, a dielectric to pyroelectric phase transition in an originally centrosymmetric crystal structure with an inherent dipole moment is found, which is induced by defect migration. From symmetry considerations, we derive space group for the MFP phase of SrTiO3. The entire electroformation cycle yields additional information about the directed movement and defect chemistry of oxygen vacancies.
More than a decade has passed since Forget and Lebel (2001) introduced the ecosystem approach to human health. Since this rst conceptual elaboration, a signicant literature has developed describing ...validity, utility, and general guidelines for a newly emerging research community.
Electric-field-driven phase transformation phenomena in multiferroic BiFeO3 are directly linked to the functionalities of electronic devices based on multiferroic materials. Understanding how the ...transformation evolves at the nanoscale under the influence of an electric field will provide fascinating insights into key parameters that utilize the transformation features. Here, we report both the electric-field-driven transient and permanent phase transformations in highly strained BiFeO3 thin films and their transformation dynamics at the nanoscale. We found that two distinct transient and permanent phase transformations were triggered below and above a coercive voltage of the polymorphic phase, indicating that ferroelectric polarization switching could promote permanent phase transformations. We also found that the transient transformations evolve via complex phase boundary motions between the coexisting phases, whereas permanent transformations occurred via nucleation of the other phases.
Diffraction Anomalous Fine Structure (DAFS) combines the long‐range, crystallographic sensitivity of X‐ray diffraction with the short‐range sensitivity of X‐ray Absorption Spectroscopy (XAS). In ...comparison to other spectroscopic methods, DAFS can additionally distinguish phases of different translational symmetry by choice of momentum transfer, or isolate spectra from chemically identical atoms on various Wyckoff sites of a crystal's structure using crystallographic weights. The Anisotropy of Anomalous Scattering (AAS) extends the concept of isotropically scattering atoms to a more general case, where the atom's scattering characteristics depend on the polarization as well as the wavevector of the incident and scattered X‐rays. These can be written as tensors that reflect the local site symmetries of the resonant atom. Forbidden Reflection Near‐Edge Diffraction (FRED) is an elegant way to measure AAS by using reflections that are extinguished in the special case of isotropically scattering atoms. They can only be observed due to the non‐isotropic contributions at photon energies in the vicinity of an absorption edge where electronic transitions occur. Combining the site selectivity of DAFS with the information accessible through AAS allows probing the short‐range order and local orbitals of selected atoms in a crystal structure of a chosen phase. The present condensed review gives a brief overview on the pioneer work, the theory and sensitivities as well as selected recent applications of these powerful and promising Resonant X‐ray Diffraction (RXD) methods. Additionally, some recent work of the authors is included exemplarily for the model structure rutile TiO2 presenting the progress in measurement and interpretation.
Diffraction Anomalous Fine Structure (DAFS) combines the long‐range, crystallographic sensitivity of X‐ray diffraction with the short‐range sensitivity of X‐ray Absorption Spectroscopy (XAS). The Anisotropy of Anomalous Scattering (AAS) extends the concept of isotropically scattering atoms to a more general case, where the atom's scattering characteristics depend on the polarization as well as the wavevector of the incident and scattered X‐rays. The present condensed review gives a brief overview on the pioneer work, the theory and sensitivities as well as selected recent applications of these powerful and promising Resonant X‐ray Diffraction (RXD) methods.
It is demonstrated that high‐resolution energy‐dispersive X‐ray fluorescence mapping devices based on a micro‐focused beam are not restricted to high‐speed analyses of element distributions or to the ...detection of different grains, twins and subgrains in crystalline materials but can also be used for the detection of dislocations in high‐quality single crystals. Si single crystals with low dislocation densities were selected as model materials to visualize the position of dislocations by the spatially resolved measurement of Bragg‐peak intensity fluctuations. These originate from the most distorted planes caused by the stress fields of dislocations. The results obtained by this approach are compared with laboratory‐based Lang X‐ray topographs. The presented methodology yields comparable results and it is of particular interest in the field of crystal growth, where fast chemical and microstructural characterization feedback loops are indispensable for short and efficient development times. The beam divergence was reduced via an aperture management system to facilitate the visualization of dislocations for virtually as‐grown, non‐polished and non‐planar samples with a very pronounced surface profile.
A laboratory X‐ray topography technique is presented. One of the advantages of this technique is that it can be used to visualize dislocations in non‐polished and non‐planar crystals with a very pronounced surface profile.
PDF
