Coherent laser radiation has enabled many scientific and technological breakthroughs including Bose-Einstein condensates, ultrafast spectroscopy, superresolution optical microscopy, photothermal therapy, and long-distance telecommunications. However, it has remained a challenge to refrigerate liquid media (including physiological buffers) during laser illumination due to significant background solvent absorption and the rapid (∼ps) nonradiative vibrational relaxation of molecular electronic excited states. Here we demonstrate that single-beam laser trapping can be used to induce and quantify the local refrigeration of physiological media by >10°C following the emission of photoluminescence from upconverting yttrium lithium fluoride (YLF) nanocrystals. A simple, low-cost hydrothermal approach is used to synthesize polycrystalline particles with sizes ranging from <200 nm to >1 μm.

A novel Na3V2O2(PO4)2F@carbon/graphene three dimensional (3D)architecture (NVPF@C/G) is developed through a simple approach for the first time, which demonstrates superior sodiation properties for Na-ion batteries.

At rest, central venous pressure (CVP) falls when cardiac output (CO) rises. This can be attributed to flow-dependent redistribution of blood volume from central to peripheral blood vessels. In contrast, CVP rises during dynamic exercise despite a rise in CO. Therefore peripheral circulatory changes during exercise must counteract the factors that lower CVP when CO rises during rest. Our objectives were to determine the importance of blood flow, the muscle pump, and reflexes on changes in ventricular filling pressure during dynamic exercise. In seven dogs with a surgically produced atrioventricular (AV) block, normal relationships between CO and CVP were established by AV-linked pacing (normal heart rates) during rest and exercise. Cardiac output was altered during rest and treadmill exercise (4 miles/h at 0, 10, or 20% grade) by changing ventricular pacing rate to establish curves relating delta CVP to delta CO. These curves were displaced rightward (higher CO) and upward (higher CVP) by exercise because of the muscle pump. Changing CO by pacing during rest and exercise revealed a constant slope for delta CVP/delta CO of -2.7 mmHg.l-1.min-1. Blockade of reflex vasoconstriction and venoconstriction with hexamethonium at rest and during mild exercise (to isolate effects of the muscle pump) did not alter these slopes or the displacement of the curves by exercise, although CVP was 4.3 mmHg lower at a given CO after blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Sodium yttrium fluoride (β-NaYF ) nanowires (NWs) with a hexagonal crystal structure are synthesized using a low-cost hydrothermal process and are shown to undergo laser refrigeration based on an upconversion process leading to anti-Stokes (blueshifted) photoluminescence. Single-beam laser trapping combined with forward light scattering is used to investigate cryophotonic laser refrigeration of individual NWs through analysis of their local Brownian dynamics.

Sodium yttrium fluoride (NaYF 4) is an important upconverting material with many potential uses in chemistry, materials science, and biology, which can be synthesized hydrothermally in both cubic (α) and hexagonal (β) crystallographic polymorphs. Understanding the mechanisms underlying the phase conversion between the cubic and hexagonal polymorphs is of great interest to help inform future efforts to synthesize atomically-precise quantum materials with well-defined sizes and morphologies. In this work, we use a combination of analytical transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), powder X-ray diffraction (XRD), in situ liquid cell TEM, atom probe tomography (APT), and extended x-ray absorption fine structure (EXAFS) measurements to show that the hexagonal NaYF 4 nanowires form through a non-classical crystal growth mechanism involving the formation and subsequent oriented attachment of mesocrystals consisting of cubic (α) phase units. EXAFS spectroscopy also suggests that substitutional Yb 3+ point defects within NaYF 4 are distributed evenly throughout the crystal lattice without clustering, and also that they may exhbit selective substitution into one of the two possible trivalent yttrium sites in the unit cell for hydrothermally synthesized β-NaYF 4 .

The development of color centers in diamond as the basis for emerging quantum technologies has been limited by the need for ion implantation to create the appropriate defects. We present a versatile method to dope diamond without ion implantation by synthesis of a doped amorphous carbon precursor and transformation at high temperatures and high pressures. To explore this bottom-up method for color center generation, we rationally create silicon vacancy defects in nanodiamond and investigate them for optical pressure metrology. In addition, we show that this process can generate noble gas defects within diamond from the typically inactive argon pressure medium, which may explain the hysteresis effects observed in other high-pressure experiments and the presence of noble gases in some meteoritic nanodiamonds. Our results illustrate a general method to produce color centers in diamond and may enable the controlled generation of designer defects.

Cadmium sulfide (CdS) nanostructures have attracted a significant amount of attention for a variety of optoelectronic applications including photovoltaic cells, semiconductor lasers, and solid-state laser refrigeration due to their direct bandgap around 2.42 eV and high radiative quantum efficiency. Nanoribbons (NRs) of CdS have been claimed to laser cool following excitation at 514 and 532 nm wavelengths by the annihilation of optical phonons during anti-Stokes photoluminescence. To explore this claim, we demonstrate a novel optomechanical experimental technique for microthermometry of a CdSNR cantilever using Young’s modulus as the primary temperature-dependent observable. Measurements of the cantilever’s fundamental acoustic eigenfrequency at low laser powers showed a red-shift in the eigenfrequency with increasing power, suggesting net heating. At high laser powers, a decrease in the rate of red-shift of the eigenfrequency is explained using Euler–Bernoulli elastic beam theory, considering Hookean optical-trapping force. A predicted imaginary refractive index for CdSNR based on experimental temperature measurement agrees well with a heat transfer analysis that predicts the temperature distribution within the cantilever and the time required to reach steady state (<100 μs). This approach is useful for investigating solid-state laser refrigeration of a wide variety of material systems without the need for complex pump/probe spectroscopy.

The paper reports a dual-layer shell hollow nanostructure as drug carrier that provides instant on/off function for drug release and contrast enhancement for multi-modal imaging. The on-demand drug release is triggered by irradiation of an external magnetic field. The nanocarrier also demonstrates a high drug loading capacity and synergistic magnetic-thermal and chemo-therapy.