A major problem challenging specialists in present-day materials sciences is the development of compact, cheap to fabricate heat sinks for electronic devices, primarily for computer processors, semiconductor lasers, high-power microchips, and electronics components. The materials currently used for heat sinks of such devices are aluminum and copper, with thermal conductivities of about 250 W/(m·K) and 400 W/(m·K), respectively. Significantly, the thermal expansion coefficient of metals differs markedly from those of the materials employed in semiconductor electronics (mostly silicon); one should add here the low electrical resistivity metals possess. By contrast, natural single-crystal diamond is known to feature the highest thermal conductivity of all the bulk materials studied thus far, as high as 2,200 W/(m·K). Needless to say, it cannot be applied in heat removal technology because of high cost. Recently, SiC- and AlN-based ceramics have started enjoying wide use as heat sink materials; the thermal conductivity of such composites, however, is inferior to that of metals by nearly a factor two. This prompts a challenging scientific problem to develop diamond-based composites with thermal characteristics superior to those of aluminum and copper, adjustable thermal expansion coefficient, low electrical conductivity and a moderate cost, below that of the natural single-crystal diamond. The present review addresses this problem and appraises the results reached by now in studying the possibility of developing composites in diamond-containing systems with a view of obtaining materials with a high thermal conductivity.

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The cover picture shows a microfl uidic channel and the magnetochromatic microspheres it generates. From a single-synthesis environment, structural-colored microspheres are synthesized by combining an optofl uidic approach with a magnetic property tuning method. The main image features the dynamic color tuning capability of the method; differently colored microspheres are generated in a single microfl uidic channel, and color can be changed in real-time during the synthesis process. The microspheres are produced with controlled and heterogeneous optical properties. They comprise 1D chain arrangements of magnetic nanoparticles, as shown by the microsphere in the foreground. The magnetic nanoparticles enable the microspheres to have the unique structural color. Orientation-dependent color diffraction of the magnetochromatic microspheres can be utilized to form structural color patterns using a patterned magnet. For more information, please read the Communication "Real-Time Optofl uidic Synthesis of Magnetochromatic Microspheres for Reversible Structural Color Patterning" by S. Kwon and coworkers, beginning on page 1163.The frontispiece features the multistrata nanoparticle-a single-core, fi ve-layered nanostructure. It combines tunable, dual-peak, UV-vis-NIR spectrum extinction characteristics; trimodal imaging contrast; a simple synthesis; and facile surface modifi cation capabilities into a single <60-nm-diameter, multifunctional nanosphere that seeks to relieve current methodological limitations by coupling diagnostics and therapeutics into one single theranostic tool. The image shows a model of the interior, multilayered, metallodielectric structure, including a schematic of the fabrication protocol. For more information, please read the Communication "The Multistrata