The designed construction of extended porous frameworks from soluble molecular building blocks represents one of the most challenging issues facing synthetic chemistry today. Recently, intense research activities directed toward the development of this field have included the assembly of inorganic metal clusters,1 coordination complexes,2 and organic molecules3 of great diversity into extended motifs that are held together either by strong metal-ligand bonding or by weaker bonding forces such as hydrogen-bonding and π-π interactions. Materials that have been produced in this way are referred to as modular since they are assembled from discrete molecules which can be modified to have well-defined function.4 The fact that the integrity of the building blocks is preserved during the synthesis and ultimately translated into the resulting assembled network offers numerous opportunities for designing frameworks with desirable topologies and architectures, thus paving the way for establishing connections between molecular and solid properties. At least three challenges have emerged in this area that must be reckoned with in order for the ideas of rational and designed synthesis of porous materials to become a reality with routine utility. First, it is difficult to control the orientation and stereochemistry of the building blocks in the solid state in order to achieve a given target molecular topology and architecture. Second, in most cases, the products of such assembly reactions are obtained as poorly crystalline or amorphous solids, thus prohibiting their full characterization by single-crystal X-ray diffraction techniques. Third, access to the pores within open structuressan aspect that is so critical to their utility as porous materialssis often prevented by either selfinterpenetration as observed for very open frameworks or strong host-guest interactions that lead to the destruction of the host framework when removal or exchange of guests is attempted. To define and investigate the parameters contributing to the assembly of materials from molecular building blocks, we have established a program aimed at constructing modular porous networks by linking inorganic metal sulfide clusters and organic molecules with transition metal ions. Our work has focused primarily on studying the issues outlined above, and this Account presents our progress toward finding viable and general solutions to these challenges. This is illustrated by some representative examples chosen from the chemistry developed in our research effort for the three building blocks shown in a-c. Their functionality, shape, size, and

Synthetic Strategies, Structure Patterns, and Emerging Properties in the Chemistry of Modular Porous Solids†

Vostok (Antarctica) ice core: Atmospheric chemistry changes over the last climatic cycle (160,000 years)

The Pearl River Origin area, Qujing District of Yunnan Province, has one of the highest female lung cancer mortality rates in China. Smoking was excluded as a cause of the lung cancer excess because almost all women were non-smokers. Crystalline silica embedded in the soot emissions from coal combustion was found to be associated with the lung cancer risk in a geographical correlation study. Lung cancer rates tend to be higher in places where the Late Permian C1 coal is produced. Therefore, we have hypothesized the two processes: C1 coal combustion --> nanoquartz in ambient air --> lung cancer excess in non-smoking women. We propose to conduct a retrospective cohort study to test the hypothesis above. We will search historical records and compile an inventory of the coal mines in operation during 1930–2009. To estimate the study subjects' retrospective exposure, we will reconstruct the historical exposure scenario by burning the coal samples, collected from operating or deserted coal mines by coal geologists, in a traditional firepit of an old house. Indoor air particulate samples will be collected for nanoquartz and polycyclic aromatic hydrocarbons (PAHs) analyses. Bulk quartz content will be quantified by X-ray diffraction analysis. Size distribution of quartz will be examined by electron microscopes and by centrifugation techniques. Lifetime cumulative exposure to nanoquartz will be estimated for each subject. Using the epidemiology data, we will examine whether the use of C1 coal and the cumulative exposure to nanoquartz are associated with an elevated risk of lung cancer. The high incidence rate of lung cancer in Xuan Wei, one of the counties in the current study area, was once attributed to high indoor air concentrations of PAHs. The research results have been cited for qualitative and quantitative cancer risk assessment of PAHs by the World Health Organization and other agencies. If nanoquartz is found to be the main underlying cause of the lung cancer epidemic in the study area, cancer potency estimates for PAHs by the international agencies based on the lung cancer data in this study setting should then be updated.

/pdf/nanoquartz-in-late-permian-c1-coal-and-the-high-incidence-of-3txaag6hsi.pdf

Nanoquartz in Late Permian C1 coal and the high incidence of female lung cancer in the Pearl River Origin area: a retrospective cohort study

Aseptic cultures of Paxillus involutus Fr. and clones of Betula pendula Roth. and B. pubescens Ehrh. were used in experiments, involving X-ray microanalysis and split-plate culture, to investigate the mechanism of ectomycorrhizal amelioration of zinc toxicity to Betula. Results imply that as the fungal mycelium colonizes fresh soil, zinc is adsorbed to the surface of hyphae, thereby lowering the concentration of zinc in the soil solution surrounding roots. In consequence, less zinc is taken up, and growth is better than in the non-mycorrhizal condition. The results also show that the metal may be adsorbed to electronegative sites in the hyphal cell walls and extra-hyphal, polysaccharide slime. The possible dual role of this slime in fungus/Betula compatibility and the amelioration mechanism is discussed.

Zinc tolerance in Betula spp. IV: The mechanism of ectomycorrhizal amelioration of zinc toxicity

A review of Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Resonance Raman Scattering (SERRS) from biomolecules adsorbed on a metal surface is given. Advantages and applications of these new vibration spectroscopic methods particularly in characterize in-situ the chemical identity, structure, orientation, chemical and electrochemical reactions of biological specimens adsorbed at charged surfaces are discussed. The technical aspects of the instrumentation and procedure as also the fundamentals of the SERS theory are exposed. Different applications show that SERS-and SERRS spectroscopy are powerful in-situ methods to study the interfacial behaviour of biomolecules. Moreover, the high enhancement factor of the Raman scattering intensity creates a new technique for obtaining high resolution vibrational spectra of biomolecules from rather diluted aqueous solutions down to 10−8 M.

Surface enhanced raman scattering of biomolecules

Almost everyone will have seen a micrograph which is scanned in synchronism with the primary produced by a scanning electron microscope. These electron beam. Secondary electrons are detected and dramatic photographs make microscopic animals used to form the display which results in the dramatic, appear as monsters in popular scientific books and high depth of field images with which we are familiar. programmes, showing that the scanning The

http://iopscience.iop.org/article/10.1088/0031-9120/17/3/304/pdf

Scanning Electron Microscopy.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Judith A Smith

Author Tools

Chat about Author

Papers

Scanning Electron Microscopy.