OBJECTIVE Uterine overdistention is thought to induce preterm labor in women with twin and multiple pregnancies, but the pathophysiology remains unclear. We investigated for the first time the pathogenesis of preterm birth associated with rapid uterine distention in a pregnant nonhuman primate model. STUDY DESIGN A nonhuman primate model of uterine overdistention was created using preterm chronically catheterized pregnant pigtail macaques (Macaca nemestrina) by inflation of intraamniotic balloons (N = 6), which were compared to saline controls (N = 5). Cesarean delivery was performed due to preterm labor or at experimental end. Microarray, quantitative reverse transcriptase polymerase chain reaction, Luminex (Austin, TX), and enzyme-linked immunosorbent assay were used to measure messenger RNA (mRNA) and/or protein levels from monkey (amniotic fluid, myometrium, maternal plasma) and human (amniocytes, amnion, myometrium) tissues. Statistical analysis employed analysis of covariance and Wilcoxon rank sum. Biomechanical forces were calculated using the law of Laplace. RESULTS Preterm labor occurred in 3 of 6 animals after balloon inflation and correlated with greater balloon volume and uterine wall stress. Significant elevations of inflammatory cytokines and prostaglandins occurred following uterine overdistention in an “inflammatory pulse” that correlated with preterm labor (interleukin [IL]-1β, tumor necrosis factor [TNF]-α, IL-6, IL-8, CCL2, prostaglandin E2, prostaglandin F2α, all P < .05). A similar inflammatory response was observed in amniocytes in vitro following mechanical stretch (IL1β, IL6, and IL8 mRNA multiple time points, P < .05), in amnion of women with polyhydramnios (IL6 and TNF mRNA, P < .05) and in amnion (TNF-α) and myometrium of women with twins in early labor (IL6, IL8, CCL2, all P < .05). Genes differentially expressed in the nonhuman primate after balloon inflation and in women with polyhydramnios and twins are involved in tissue remodeling and muscle growth. CONCLUSION Uterine overdistention by inflation of an intraamniotic balloon is associated with an inflammatory pulse that precedes and correlates with preterm labor. Our results indicate that inflammation is an early event after a mechanical stress on the uterus and leads to preterm labor when the stress is sufficiently great. Further, we find evidence of uterine tissue remodeling and muscle growth as a common, perhaps compensatory, response to uterine distension.

Semiconductor nanocrystals, or quantum dots (QDs), are candidates for biological sensing, photovoltaics, and catalysis due to their unique photophysical properties. The most studied QDs are composed of heavy metals like cadmium and lead. However, this engenders concerns over heavy metal toxicity. To address this issue, numerous studies have explored the development of nontoxic (or more accurately less toxic) quantum dots. In this Review, we select three major classes of nontoxic quantum dots composed of carbon, silicon and Group I-III-VI elements and discuss the myriad of synthetic strategies and surface modification methods to synthesize quantum dots composed of these material systems.

A one-step method to produce ≈12 nm hydrodynamic diameter water-soluble CdSe/ZnS quantum dots (QDs), as well as CdS/ZnS, ZnSe/ZnMnS/ZnS, AgInS2 /ZnS, and CuInS2 /ZnS QDs, by ligand exchange with a near-monolayer of organosilane caps is reported. The method cross-links the surface-bound silane ligands such that the samples are stable on the order of months under ambient conditions. Furthermore, the samples may retain a high quantum yield (60%) over this time. Several methods to functionalize aqueous QD dispersions with proteins and fluorescent dyes have been developed with reaction yields as high as 97%.

It is a paradigm that the exciton splitting characteristics of type II quantum dots (QDs) result in low quantum yield materials. However, reported herein is the synthesis of ZnSe/CdS/ZnS type II QDs with quantum yields as high as 61%. Most interesting is the fact that the enhancement in brightness is due to an increase in the radiative rate, rather than the suppression of surface trap-related non-radiative processes which was found to be minimal. These QDs have been water-solubilized using two different methods and retain a substantial fraction of their brightness. The watersoluble type II QDs were conjugated to a dye to examine their potential as fluorescence resonance energy transfer (FRET) donors. A significant FRET efficiency of 0.61 ± 0.1% was measured using time-correlated single photon counting, which demonstrates the potential for these materials to be used in FRET-based chemical and biological sensing applications.

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Small Cu(0)-nanoparticles (NPs) are fabricated utilizing CuSO 4 •5H 2 O, surfactant (SDS) and ascorbic acid in aqueous medium. Its outstanding catalytic activity under low catalyst loading is developed toward reductive cleavage of isoxazoline, carbonyl azide and domino cyclization to furnish valuable 2-hydroxy-4-keto esters, primary amides and a new class of heterocycle, 4-hydroxy-2-pyrroline-5-one.Scheme 1 Fabrication of Cu(0)-NPs and their catalytic activity. † Electronic supplementary information (ESI) available: procedures, characterization data, spectra.

The synthesis of metal arsenide semiconductor nanocrystals is challenging compared to other conventional materials (e.g., II–VI family CdSe) due to a high degree of covalency in crystal lattice and a lack of a variety of effective pnictide precursors. We reported here the use of [(Me3Si)2N]2AsCl (“arsenic silylamide”) to synthesize a variety of binary and tertiary quantum confined species such as InAs (III–V), Cd3As2 (II–V), and Cu3AsS4 (enargite, I3–V–VI4) nanocrystals. The physical properties of this reagent resolve many issues, especially concerning safety, with other precursors such as pyrophoric (TMS)3As and highly toxic AsH3 gas. Furthermore, usage of this reagent has allowed for the realization of enargite quantum rods for the first time. The role of arsenic silylamide in the reaction mechanism to form InAs has been elucidated with a combination of NMR spectroscopy as well as quantum chemical modeling. Cd3As2 and Cu3AsS4 nanostructures form via a diffusion mechanism.

Silver dimetal chalcogenides (Ag–V–VI2) are ternary semiconductors that have potential alternative energy applications due to their optimal band gaps and large extinction coefficients. The synthesis of these materials is challenging due to the lack of effective pnictide precursors. We report the use of tris­[N,N-bis­(trimethylsilyl)­amido]antimony (Sb­[N­(SiMe3)2]3) and tris­[N,N-bis­(trimethylsilyl)­amido]bismuth (Bi­[(N­(SiMe3)2]3) to synthesize nanocrystalline AgSbSe2 and AgBiSe2 quantum dots. The use of these reagents results in the creation of high quality nanomaterials with good crystallinity and narrow size distributions. Furthermore, electrical measurements on monolithic pellets of processed AgSbSe2 and AgBiSe2 nanomaterials demonstrate linear current–voltage behavior at room temperature, which indicates potential for use in electrical applications.