Microenvironment responsive nanomaterials are attractive for therapeutic applications with regional specificity. Here we report pH responsive gold nanoparticles which are designed to aggregate in acidic condition similar to cancer environment and returned to its original disassembled states in a physiological pH. The pH responsive behavior of the particles is derived by change of electrostatic interaction among the particles where attraction and repulsion play a major role in low and high pH of the environment, respectively. Since different electrostatic interaction behavior of the particles in varied pH is induced not by irreversible chemical change but by simple protonation differences, the pH responsive process of assembly and disassembly is totally reversible. The low pH specific aggregation of gold nanoparticles resulted in red shift of plasmonic absorption peak and showed higher photothermal efficacy in acidic pH than in normal physiological pH. The low pH specific photothermal effect with long wave laser irradiation was directly applied to cancer specific photothermal therapy and resulted higher therapeutic effect for melanoma cancer cells than non-pH responsive gold nanoparticles.

BackgroundSelective lumbar nerve root block (SNRB) is generally accepted as an effective treatment method for back pain with sciatica. However, it requires devices producing radioactive materials such as C-arm fluoroscopy. This study evaluated the usefulness of the longitudinal view of transverse process and needles for medial branch block as landmarks under ultrasonography.MethodsWe performed selective nerve root block for 96 nerve roots in 61 patients under the guidance of ultrasound. A curved probe was used to identify the facet joints and transverse processes. Identifying the lumbar nerve roots under the skin surface and ultrasound landmarks, the cephalad and caudal medial branch blocks were undertaken under the transverse view of sonogram first. A needle for nerve root block was inserted between the two transverse processes under longitudinal view, while estimating the depth with the needle for medial branch block. We then injected 1.0 mL of contrast medium and checked the distribution of the nerve root with C-arm fluoroscopy to evaluate the accuracy. The visual analog scale (VAS) was used to access the clinical results.ResultsSeven SNRBs were performed for the L2 nerve root, 15 for L3, 49 for L4, and 25 for L5, respectively. Eighty-six SNRBs (89.5%) showed successful positioning of the needles. We failed in the following cases: 1 case for the L2 nerve root; 2 for L3; 3 for L4; and 4 for L5. The failed needles were positioned at wrong leveled segments in 4 cases and inappropriate place in 6 cases. VAS was improved from 7.6 ± 0.6 to 3.5 ± 1.3 after the procedure.ConclusionsFor SNRB in lumbar spine, the transverse processes under longitudinal view as the ultrasound landmark and the needles of medial branch block to the facet joint can be a promising guidance.

As an alternative to lead halide perovskites, various types of lead-free perovskites have been recently studied for optoelectronic materials. This paper reports the synthesis of highly phase-pure Cs 2 NaBiX 6 (X = Cl, Br) double perovskite (DP) nanocrystals (NCs). They show characteristic absorption features of sharp and discrete peaks mostly originating from the Bi 3+ s−p transition (6s 2 → 6s 1 p 1 ) in [BiX 6 ] 3− units within the crystal lattice of the elpasolite structure. Such unique optical properties are attributed to the non-bonding character of electropositive sodium and electronically isolated [BiX 6 ] 3− units in crystals. The shape of Cs 2 NaBiX 6 NCs could be quantitatively controlled by adjusting the reaction temperature. Reaction temperatures above 180 °C favor development of a cuboctahedral (CO) shape, whereas development of a cuboidal (CB) shape is favored below 170 °C. CB NCs can be subsequently converted to CO NCs by heating to 200 °C. The CO NCs promote the growth of heterostructure adducts on the (111) facets; these adducts could be posteliminated by etching. Mn-doped Cs 2 NaBiCl 6 NCs are synthesized; they show efficient energy transfer from the NC host to the dopants. The synthesis and shape control of Cs 2 NaBiX 6 NCs and Mn-doped Cs 2 NaBiCl 6 NCs could expand a new class of lead-free DP NCs applicable to optoelectronic applications.

In his last letter to Hardy, Ramanujan introduced mock theta functions. For each of his examples f (q), Ramanujan claimed that there is a collection {G j } of modular forms such that for each root of unity ζ, there is a j such that limMoreover, Ramanujan claimed that this collection must have size larger than 1. In his 2001 PhD thesis, Zwegers showed that the mock theta functions are the holomorphic parts of harmonic weak Maass forms. In this paper, we prove that there must exist such a collection by establishing a more general result for all holomorphic parts of harmonic Maass forms. This complements the result of Griffin, Ono, and Rolen that shows such a collection cannot have size 1. These results arise within the context of Zagier's theory of quantum modular forms. A linear injective map is given from the space of mock modular forms to quantum modular forms. Additionally, we provide expressions for "Ramanujan's radial limits" as L-values.

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