Background: Colorectal cancer incidence among young adults in the United States is on the rise, but whether this phenomenon is present in other parts of the world is not well documented. This study aims to explore the temporal change of incidence rates for colorectal cancer in various countries across the globe. Methods: We extracted colorectal cancer incidence and population data from 1988 to 2007 based on data from the International Agency for Research on Cancer and compared incidence between age groups. Twelve representative jurisdictions from five continents were selected. Young-onset colorectal cancer cases were defined as those ages <50 years. Joinpoint regression was used to measure the trends of colorectal cancer incidence and to estimate the annual percent change (APC). Results: The APC for those ages <50 years was noted to be increasing at a faster rate as compared with those ages !50 years in many regions, including Australia (þ1.10% vs. À0.35%), Brazil (þ9.20% vs. þ5.72%), Canada (þ2.60% vs. À0.91%), China-Hong Kong (þ1.82% vs. À0.10%), China-Shanghai (þ1.13% vs. À2.68%), Japan (þ2.63% vs. þ0.90%), the United Kingdom (þ3.33% vs. þ0.77%), and the United States (þ1.98% vs. À2.88%). These trends were largely driven by rectal cancer, except in Brazil and the United Kingdom. Conclusions: Increasing incidence of young-onset colorectal cancer was noted in many regions across the globe. Impact: Further studies focusing on young-onset colorectal cancer, particularly with regard to risk factors and establishing the optimal age of screening, are warranted.

This Focus Review surveys representative examples of pH-controllable supramolecular systems with interesting features and state-of-the-art applications such as 1) conformational changes within individual molecules; 2) folding/unfolding of polymers; 3) simultaneous binding of cations and anions; 4) logic function; 5) ON-OFF switchable colorimetric sensing; 6) translocation of macrocycle-in-rotaxane molecules; 7) large-scale movement within molecules; and 8) regulation of the substrate flow in nanocontainers. In particular, systems will be discussed that involve: pH-induced conformational changes of a resorcinarene cavitand and a bis(iron porphyrin) complex; pH control in assembly and disassembly of supramolecular systems stabilized with different major noncovalent interactions; pH-driven movements of interlocked molecules involving rotaxanes, molecular elevators, and molecular muscles; and, finally, multicomponent supramolecular systems immobilized on solid supports as pH-responsive nanovalves for the controlled release of specific substrates. Recent advances in the understanding of pH-controllable supramolecular systems have led to the construction of meaningful molecular machines for electronic and biological applications that are amenable to control by simple perturbation with acids and bases.

We describe the use of hydrophobic poly(aryl ether) dendrons to peripherally functionalize hydrophilic amine-containing superparamagnetic iron oxide microspheres (SPIO-NH2) in one step via imine formation. The reversible formation of imine bonds in the absence/presence of water renders dynamic control of the hydrophilicity and hydrophobicity of the microspheres (SPIO-Gn). The dynamic nature of the imine-containing dendronized microspheres (SPIO-Gn) can be "fixed" by locking the reversible 2,6-diiminopyridyl moieties with metal cations (Zn2+, Co2+, and Ni2+) to afford kinetically stable dendronized microspheres (SPIO-Gn-M). Isolation of these microspheres is facilitated by convenient magnetic separation by an externally applied magnetic field. Characterization of these novel organic-inorganic hybrid microspheres has been performed by various techniques using UV/visible absorption and Fourier transform infrared spectroscopies, transmission electron microscopy, thermogravimetric analysis, and a vibrating sample magnetometer. We have demonstrated the stability and reversible switching of hydrophilicity/hydrophobicity by contact-angle measurements. In particular, the hydrophilic SPIO-NH2 microspheres demonstrated a contact angle of 42 +/- 2 degrees when a drop of water was added to a SPIO-NH2-coated mica surface. On the other hand, the hydrophobic SPIO-Gn-M dendronized microspheres demonstrated a contact angle of 85 +/- 2 degrees , an observation that involves an increase of the contact angle of over 40 degrees . Furthermore, when a drop of water was placed on a dynamic SPIO-Gn-coated mica surface, the contact angle of the water droplet decreased in time. Comparatively, the rate of decrease of the contact angle is H2O > 1% Co(OAc)2/H2O > N,N'-dimethylformamide/H2O (1:1).

This Feature Article gives a summary on the conformational and supramolecular properties of a special type of click molecules, namely, main chain and cyclic oligo- and polytriazoles. The triazole ring is an interesting structural motif since it is a hydrogen bond donor and acceptor, a large molecular dipole and also a metal ligand. It can interact with a wide variety of functionalities, e.g. hydrogen bonding partners (e.g. amides or anions), molecular dipoles, and metal ions to generate many fascinating conformational features such as pseudo rod-like, U-turn, helical, double helical structures, beta-strands and beta-sheets. Oligo- and polytriazoles can also exhibit interesting supramolecular attributes such as host-guest complexation, self assembly, chemosensing and gelating properties. It is believed that many new and unique conformational and supramolecular properties can be created by incorporating the correct type of functional group partners into the oligo- and polytriazole backbone. This type of research can also advance our understanding on functional properties of such triazole-rich compounds.

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