Enhancing the stiffness of vertical graphene sheets through ion beam irradiation and fluorination

Many applications of graphene can benefit from the enhanced mechanical robustness of graphene-based components. We report how the stiffness of vertical graphene (VG) sheets is affected by the introduction of defects and fluorination, both separately and combined. The defects were created using a high-energy ion beam while fluorination was performed in a XeF₂ etching system. After ion bombardment alone, the average effective reduced modulus (E _r), equal to ∼4.9 MPa for the as-grown VG sheets, approximately doubled to ∼10.0 MPa, while fluorination alone almost quadrupled it to ∼18.4 MPa. The maximum average E _r of ∼32.4 MPa was achieved by repeatedly applying fluorination and ion bombardment. This increase can be explained by the formation of covalent bonds between the VG sheets due to ion bombardment, as well as the conversion from sp² to sp³ and increased corrugation due to fluorination.

Atomic-scale characterization of oxide thin films gated by ionic liquid

Ionic liquids (ILs) have received considerable interest for use in electrostatic gating in complex oxide systems. Understanding the ionic liquid/oxide interface, and any bias-induced electrochemical degradation, is critical for the interpretation of transport phenomena. The integrity of the interface between ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate and La1/3Sr2/3FeO3 under various biasing conditions was examined by analytical transmission electron microscopy, and we report film degradation in the form of an irreversible chemical reaction regardless of the applied bias. This results in an intermixing region of 4-6 nm at the IL/oxide interface. Electron energy loss spectroscopy shows La and Fe migration into the ionic liquid, resulting in secondary phase formation under negative bias. Our approach can be extended to other ionic liquid/oxide systems in order to better understand the electrochemical stability window of these device structures.

In situ electrochemical lithiation/delithiation observation of individual amorphous Si nanorods

In situ electrochemical lithiation and delithiation processes inside a nanobattery consisting of an individual amorphous Si nanorod and ionic liquid were explored. Direct formation of the crystalline Li(22)Si(5) phase due to the intercalation of Li ions was observed. In addition, the role of the electrolyte-nanorod interface was examined. It was observed that the lithiation of Si nanorods is dominated by surface diffusion. Upon the delithiation process, partial decomposition of Li(22)Si(5) particles was observed which can explain the irreversible capacity loss that is generally seen in Si anodes. This study shows that the radial straining due to lithiation does not cause cracking in nanorods as small in diameter as 26 nm, whereas cracks were observed during the lithiation of 55 nm Si nanorods.

Supplementary feeding in programmes in developing countries: lessons of the eighties

This extensive report reviews the important lessons learned during the 1980s on supplementary food distribution for the vulnerable groups in developing countries. These lessons may be useful in making such programmes a more cost-effective option in narrowing the food/nutrient gap in intake among the programme beneficiaries. This report follows a similar report published at the end of the 1970s by the author and George Beaton for UNICEF. The primary focus in the study has been the food distribution among young children, particularly schoolchildren, and also in pregnant and lactating women. The data have been gathered through a comprehensive search of the literature, official reports and documents from several United Nations agencies, aid agencies, national and international institutions. As well as original research papers on theoretical and applied issues, reports on design and evaluation of specific programmes in over 20 countries are studied. Consideration of programme design examines objectives, nutrient/food gap, poverty reduction, malnutrition, mother and child feeding practices, foods, ration sizes, leakages, targeting, coverage, integration of feeding and health care. Potential and measured benefits are considered in the light of the reports published at the end of the 1970s and consequent analysis of work up until the end of the 1980s. Programme costs are documented. In a discussion on context and input, the functional significance of mild and moderate malnutrition is considered, together with diet and physical activity. The author offers some thoughts on future directions and high-lights the need for further research.

Supplementary feeding in programmes in developing countries: lessons of the eighties

This extensive report reviews the important lessons learned during the 1980s on supplementary food distribution for the vulnerable groups in developing countries. These lessons may be useful in making such programs a more cost-effective option in narrowing the food/nutrient gap in intake among the program beneficiaries. This report follows a similar report published at the end of the 1970s by the author and George Beaton for UNICEF. The primary focus in the study has been the food distribution among young children, particularly school children, and also in pregnant and lactating women. The data have been gathered through a comprehensive search of the literature, official reports and documents from several United Nations agencies, aid agencies, national and international institutions. As well as original research papers on theoretical and applied issues, reports on design and evaluation of specific programs in over 20 countries are studied. Consideration of programme design examines objectives, nutrient/food gap, poverty reduction, malnutrition, mother and child feeding practices, foods, ration sizes, leakages, targeting, coverage, integration of feeding and health care. Potential and measured benefits are considered in the light of the reports published at the end of the 1970s and consequent analysis of work up until the end of the 1980s. Programme costs are documented. In a discussion on context and input, the functional significance of mild and moderate malnutrition is considered, together with diet and physical activity. The author offers some thoughts on future directions and highlights the need for further research.

Childhood lymphoma in southern Iran

A study of 81 childhood lymphomas diagnosed in the Department of Pathology of Pahlavi University Medical Center, Shiraz, Iran, encompassing all histologically diagnosed childhood lymphomas from the Fars Province, Southern Iran over a 14-year period (1963--1976) revealed a 3:1 male predominance and a 1:4 frequency compared to adult lymphomas. Peripheral lymphadenopathy at the initial physical examination was almost twice as common as deep node involvement. Comparison of cumulative and age-standardized (to world population) incidence rates with those of selected Tumor Registries in various continents revealed a higher rate in our region of both non-Hodgkin's and Hodgkin's lymphoma relative to some of the Western countries. Our incidence rates were in general intermediate between Western populations on one hand and some South America, African and Asian populations on the other. Hodgkin's disease accounted for 64% (males) and 88% (females) of lymphomas and mixed cellularity was the commonest histologic subtype. Histologically almost all non-Hodgkin's lymphomas were diffuse at the time of diagnosis.

Colorectal polyps and carcinoma in Southern Iran

A study was made of the prevalence of colorectal polyps (excluding juvenile polyps, familial polyposis coli and villous adenomas) and the minimum frequency of colorectal carcinoma in Southern Iran. A total of 801 large intestines from necropsies performed on individuals 20 years or older was examined with or without magnifying lens for presence of polyps. Our prevalence rate was then compared with those reported on postmortem material from the USA, Australia, South Africa (Bantus), Colombia, and Hawaii (Japanese immigrants). Our surgical pathology files were reviewed for colorectal polyps over a 22-year period (1952-1973). Colorectal carcinomas diagnosed in the Department of Pathology were reviewed over 11 years (1963-1973) and the minimum frequency rates compared with corresponding age- and sex-specific incidence rates from Connecticut, USA. The data indicate 1) a very low prevalence rate for colorectal polyps as well as carcinoma in our region and 2) a rather striking predominance of right-sided colonic carcinoma.