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1.
Nature ; 630(8015): 59-63, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38750357

ABSTRACT

Ab initio calculations have an essential role in our fundamental understanding of quantum many-body systems across many subfields, from strongly correlated fermions1-3 to quantum chemistry4-6 and from atomic and molecular systems7-9 to nuclear physics10-14. One of the primary challenges is to perform accurate calculations for systems where the interactions may be complicated and difficult for the chosen computational method to handle. Here we address the problem by introducing an approach called wavefunction matching. Wavefunction matching transforms the interaction between particles so that the wavefunctions up to some finite range match that of an easily computable interaction. This allows for calculations of systems that would otherwise be impossible owing to problems such as Monte Carlo sign cancellations. We apply the method to lattice Monte Carlo simulations15,16 of light nuclei, medium-mass nuclei, neutron matter and nuclear matter. We use high-fidelity chiral effective field theory interactions17,18 and find good agreement with empirical data. These results are accompanied by insights on the nuclear interactions that may help to resolve long-standing challenges in accurately reproducing nuclear binding energies, charge radii and nuclear-matter saturation in ab initio calculations19,20.

2.
Arch Pharm Res ; 46(3): 192-205, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36840853

ABSTRACT

Induction of the brown adipocyte-like phenotype in white adipocytes (fat browning) is considered a promising therapeutic strategy to treat obesity. Naringin, a citrus flavonoid, has antioxidant, anti-inflammatory, and anticancer activities. We examined the application of naringin as an anti-obesity compound based on an investigation of its induction of fat browning in 3T3-L1 adipocytes. Naringin did not induce lipid accumulation in differentiated 3T3-L1 adipocytes. Additionally, naringin reduced the expression levels of proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (C/EBPα) involved in adipogenesis during lipid metabolism and increased the levels of PPARα and adiponectin involved in fatty acid oxidation. The expression levels of fat browning markers uncoupling protein 1 (UCP1; involved in thermogenesis) and PR domain containing 16 (PRDM16) increased. In addition, naringin treatment resulted in the activation of PPARγ coactivator 1-alpha (PGC-1α), a factor related to UCP1 transcription and mitochondrial biogenesis. Moreover, the expression of beige adipocyte-specific genes such as Cd137, Cited1, Tbx1, and Tmem26 was also induced. The small multi-lipid droplets characteristic of beige adipocytes indicated that naringin treatment increased the levels of all lipolysis markers (hormone-sensitive lipase [HSL], adipose triglyceride lipase [ATGL], perilipin [PLIN], and protein kinase A [PKA]). Adenosine monophosphate-activated protein kinase (AMPK) and UCP1 levels increased by treatment with naringin alone; this was possibly mediated by the stimulation of the AMPK signaling pathway. According to mechanistic studies, naringin activated the thermogenic protein UCP1 via the AMPK signaling pathway. In conclusion, naringin induces fat browning and is a promising therapeutic agent for metabolic disorders based on the regulation of lipid metabolism.


Subject(s)
AMP-Activated Protein Kinases , PPAR gamma , Animals , Mice , AMP-Activated Protein Kinases/metabolism , 3T3-L1 Cells , PPAR gamma/metabolism , Adipocytes, Brown/metabolism , Signal Transduction , Obesity/metabolism , Uncoupling Protein 1/genetics , Uncoupling Protein 1/metabolism
3.
Front Psychol ; 13: 819396, 2022.
Article in English | MEDLINE | ID: mdl-35321039

ABSTRACT

Customer injustice has received considerable attention in the field of organizational behavior because it generates a variety of negative outcomes. Among possible negative consequences, customer-directed sabotage is the most common reaction, which impacts individuals' well-being and the prosperity of organizations. To minimize such negative consequences, researchers have sought to identify boundary conditions that could potentially attenuate the occurrence of customer-directed sabotage. In this study, we explore potential attenuation effects of emotional stability and attentiveness on the customer injustice-sabotage linkage. The results showed emotional stability and attentiveness moderate the relationship between customer injustice and customer-directed sabotage. Specifically, the representatives with higher (vs. lower) emotional stability or higher (vs. lower) attentiveness are less likely to engage in customer-directed sabotage when they experience customer injustice. Moreover, there is a three-way interaction among daily customer injustice, emotional stability, and attentiveness that predicts daily customer-directed sabotage. Theoretical and practical contributions, limitations, and directions for future development are also discussed.

4.
J Nanosci Nanotechnol ; 21(9): 4881-4885, 2021 Sep 01.
Article in English | MEDLINE | ID: mdl-33691883

ABSTRACT

We report the characteristics of AlN epilayers grown directly on cylindrical-patterned sapphire substrates (CPSS) by hydride vapor-phase epitaxy (HVPE). To evaluate the effect of CPSS, we analyzed the threading dislocation densities (TDDs) of AlN films grown simultaneously on CPSS and flat sapphire substrate (FSS) by transmission electron microscopy (TEM). The corresponding TDD is measured to be 5.69 x 108 cm-2 for the AlN sample grown on the CPSS that is almost an order of magnitude lower than the value of 3.43 × 109 cm-2 on the FSS. The CPSS contributes to reduce the TDs originated from the AlN/sapphire interface via bending the TDs by lateral growth during the coalescence process. In addition, the reduction of direct interface area between AlN and sapphire by CPSS reduce the generation of TDs.

5.
Int J Toxicol ; 40(1): 40-51, 2021.
Article in English | MEDLINE | ID: mdl-33148080

ABSTRACT

Clinical use of the chemotherapeutic agent vincristine (VCR) is limited by chemotherapy-induced peripheral neuropathy (CiPN). A new formulation of VCR encapsulated by nanoparticles has been proposed and developed to alleviate CiPN. We hypothesized in nonclinical animals that the nanoparticle drug would be less neurotoxic due to different absorption and distribution properties to the peripheral nerve from the unencapsulated free drug. Here, we assessed whether VCR encapsulation in nanoparticles alleviates CiPN using behavioral gait analysis (CatWalk), histopathologic and molecular biological (RT-qPCR) approaches. Adult male C57BL/6 mice were assigned to 3 groups (empty nanoparticle, nano-VCR, solution-based VCR, each n = 8). After 15 days of dosing, animals were euthanized for tissue collection. It was shown that intraperitoneal administration of nano-VCR (0.15 mg/kg, every other day) and the empty nanoparticle resulted in no changes in gait parameters; whereas, injection of solution-based VCR resulted in decreased run speed and increased step cycle and stance (P < 0.05). There were no differences in incidence and severity of degeneration in the sciatic nerves between the nano-VCR-dosed and solution-based VCR-dosed animals. Likewise, decreased levels of a nervous tissue-enriched microRNA-183 in circulating blood did not show a significant difference between the nano- and solution-based VCR groups (P > 0.05). Empty nanoparticle administration did not cause any behavioral, microRNA, or structural changes. In conclusion, this study suggests that the nano-VCR formulation may alleviate behavioral changes in CiPN, but it does not improve the structural changes of CiPN in peripheral nerve. Nanoparticle properties may need to be optimized to improve biological observations.


Subject(s)
Antineoplastic Agents, Phytogenic/toxicity , Behavior, Animal/drug effects , Gait/drug effects , Nanoparticles/toxicity , Peripheral Nervous System Diseases/chemically induced , Vincristine/toxicity , Animals , Disease Models, Animal , Male , Mice , Mice, Inbred C57BL
6.
Sci Rep ; 9(1): 242, 2019 01 18.
Article in English | MEDLINE | ID: mdl-30659228

ABSTRACT

We report herein on the design, synthesis and biological activity of Ru-based self-assembled supramolecular bowls as a potent anticancer therapeutic in human hepatocellular cancer. The potent complex induces production of reactive oxygen species (ROS) by higher fatty acid ß-oxidation and down-regulation of glucose transporter-mediated pyruvate dehydrogenase kinase 1 via reduced hypoxia-inducible factor 1α. Also, overexpressed acetyl-CoA activates the tricarboxylic acid cycle and the electron transport system and induces hypergeneration of ROS. Finally, ROS overexpressed through this pathway leads to apoptosis. Furthermore, we demonstrate that the naphthalene derived molecular bowl activates classical apoptosis via crosstalk between the extrinsic and intrinsic signal pathway. Our work into the mechanism of Ru-based self-assembled supramolecular bowls can provide valuable insight into the potential for use as a promising anticancer agent.


Subject(s)
Antineoplastic Agents/therapeutic use , Apoptosis/drug effects , Carcinoma, Hepatocellular/drug therapy , Coordination Complexes/therapeutic use , Liver Neoplasms/drug therapy , Reactive Oxygen Species/toxicity , Rubidium/therapeutic use , Antineoplastic Agents/chemical synthesis , Cell Line, Tumor , Cell Survival/drug effects , Coordination Complexes/chemical synthesis , Humans , Models, Theoretical , Reactive Oxygen Species/metabolism
7.
Technol Health Care ; 26(S1): 291-306, 2018.
Article in English | MEDLINE | ID: mdl-29710757

ABSTRACT

This study was conducted according to the method presented in the Republic of Korea Pharmacopoeia 11th Revision, aseptic test method to evaluate the suitability of sterilization for a sterile needle (4 Pin Multi-needle). In this study, four tests were conducted: sterility test, cytotoxicity test, acute toxicity test, skin sensitization test. First, in the aseptic test, the microorganism was not proliferated in the aseptic test of the medium. As a result of the performance test of the medium, it was confirmed that the microorganism developed within 3 days and the fungus was evident within 5 days. Based on this, it was confirmed that the medium was suitable, and as a result of the aseptic test, the development of microorganisms was not observed during the total culture period. Based on these results, tests were conducted which were confirmed to be suitable for aseptic testing because the development of bacteria on the provided samples was not recognized. For cytotoxicity tests ISO10993-5; 2009 (Biological Evaluation of Medical Devices, Part 5: Test for in vitro Cytotoxicity). As a result, the MEM eluate of the test substance caused very slight cytotoxicity to the fibroblasts of the mouse and was judged to be Grade 1 (Slightly cytotoxic) according to the judgment standard of ISO 10993-5. On the other hand, solvent control, negative control and positive control showed the expected results on the test. Acute Toxicity Test Results: It was judged that there was no systemic toxicity change when ICR mice were treated with 50 mL/kg B.W. of the eluate of sterile injectable needle for 72 hours. Skin sensitization test result: The Hartley guinea pig was evaluated as a substance which is evaluated as a substance which does not induce any skin reaction when skin sensitization is applied to the dissected material of the sterile injectable needle and is weak in skin sensitivity. Based on the above tests, we will study the stability and efficacy of more reliable medical devices based on the verification and performance of medical devices.


Subject(s)
Mesotherapy/methods , Needles/microbiology , Sterilization/methods , Animals , Dermatitis, Allergic Contact/microbiology , Fibroblasts/microbiology , Guinea Pigs , Mice , Reproducibility of Results , Republic of Korea , Skin Tests , Sterilization/standards , Toxicity Tests
8.
J Control Release ; 229: 106-119, 2016 05 10.
Article in English | MEDLINE | ID: mdl-27001894

ABSTRACT

The present studies were aimed at formulating AZD2811-loaded polylactic acid-polyethylene glycol (PLA-PEG) nanoparticles with adjustable release rates without altering the chemical structures of the polymer or active pharmaceutical ingredient (API). This was accomplished through the use of a hydrophobic ion pairing approach. A series of AZD2811-containing nanoparticles with a variety of hydrophobic counterions including oleic acid, 1-hydroxy-2-naphthoic acid, cholic acid, deoxycholic acid, dioctylsulfosuccinic acid, and pamoic acid is described. The hydrophobicity of AZD2811 was increased through formation of ion pairs with these hydrophobic counterions, producing nanoparticles with exceptionally high drug loading-up to five fold higher encapsulation efficiency and drug loading compared to nanoparticles made without hydrophobic ion pairs. Furthermore, the rate at which the drug was released from the nanoparticles could be controlled by employing counterions with various hydrophobicities and structures, resulting in release half-lives ranging from about 2 to 120h using the same polymer, nanoparticle size, and nanoemulsion process. Process recipe variables affecting drug load and release rate were identified, including pH and molarity of quench buffer. Ion pair formation between AZD2811 and pamoic acid as a model counterion was investigated using solubility enhancement as well as nuclear magnetic resonance spectroscopy to demonstrate solution-state interactions. Further evidence for an ion pairing mechanism of controlled release was provided through the measurement of API and counterion release profiles using high-performance liquid chromatography, which had stoichiometric relationships. Finally, Raman spectra of an AZD2811-pamoate salt compared well with those of the formulated nanoparticles, while single components (AZD2811, pamoic acid) alone did not. A library of AZD2811 batches was created for analytical and preclinical characterization. Dramatically improved preclinical efficacy and tolerability data were generated for the pamoic acid lead formulation, which has been selected for evaluation in a Phase 1 clinical trial (ClinicalTrials.gov Identifier NCT 02579226). This work clearly demonstrates the importance of assessing a wide range of drug release rates during formulation screening as a critical step for new drug product development, and how utilizing hydrophobic ion pairing enabled this promising nanoparticle formulation to proceed into clinical development.


Subject(s)
Acetanilides/administration & dosage , Antineoplastic Agents , Drug Delivery Systems , Nanoparticles , Organophosphates , Prodrugs , Quinazolines/administration & dosage , Acetanilides/chemistry , Acetanilides/pharmacokinetics , Acetanilides/therapeutic use , Animals , Antineoplastic Agents/administration & dosage , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/therapeutic use , Bone Marrow/drug effects , Bone Marrow/pathology , Cell Line, Tumor , Cholic Acid/chemistry , Deoxycholic Acid/chemistry , Dioctyl Sulfosuccinic Acid/chemistry , Humans , Hydrophobic and Hydrophilic Interactions , Male , Mice, Nude , Nanoparticles/administration & dosage , Nanoparticles/chemistry , Nanoparticles/therapeutic use , Naphthols/chemistry , Neoplasms/drug therapy , Neoplasms/pathology , Organophosphates/administration & dosage , Organophosphates/chemistry , Organophosphates/pharmacokinetics , Organophosphates/therapeutic use , Polyethylene Glycols/chemistry , Prodrugs/administration & dosage , Prodrugs/chemistry , Prodrugs/pharmacokinetics , Prodrugs/therapeutic use , Quinazolines/chemistry , Quinazolines/pharmacokinetics , Quinazolines/therapeutic use , Rats, Nude , Rats, Wistar , Tumor Burden/drug effects
9.
Sci Transl Med ; 8(325): 325ra17, 2016 Feb 10.
Article in English | MEDLINE | ID: mdl-26865565

ABSTRACT

Efforts to apply nanotechnology in cancer have focused almost exclusively on the delivery of cytotoxic drugs to improve therapeutic index. There has been little consideration of molecularly targeted agents, in particular kinase inhibitors, which can also present considerable therapeutic index limitations. We describe the development of Accurin polymeric nanoparticles that encapsulate the clinical candidate AZD2811, an Aurora B kinase inhibitor, using an ion pairing approach. Accurins increase biodistribution to tumor sites and provide extended release of encapsulated drug payloads. AZD2811 nanoparticles containing pharmaceutically acceptable organic acids as ion pairing agents displayed continuous drug release for more than 1 week in vitro and a corresponding extended pharmacodynamic reduction of tumor phosphorylated histone H3 levels in vivo for up to 96 hours after a single administration. A specific AZD2811 nanoparticle formulation profile showed accumulation and retention in tumors with minimal impact on bone marrow pathology, and resulted in lower toxicity and increased efficacy in multiple tumor models at half the dose intensity of AZD1152, a water-soluble prodrug of AZD2811. These studies demonstrate that AZD2811 can be formulated in nanoparticles using ion pairing agents to give improved efficacy and tolerability in preclinical models with less frequent dosing. Accurins specifically, and nanotechnology in general, can increase the therapeutic index of molecularly targeted agents, including kinase inhibitors targeting cell cycle and oncogenic signal transduction pathways, which have to date proved toxic in humans.


Subject(s)
Aurora Kinases/antagonists & inhibitors , Nanoparticles/chemistry , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Animals , Aurora Kinases/metabolism , Bone Marrow/drug effects , Bone Marrow/pathology , Cell Line, Tumor , Drug Liberation , Female , Humans , Male , Mass Spectrometry , Mice , Mice, SCID , Organophosphates/chemistry , Organophosphates/pharmacokinetics , Organophosphates/pharmacology , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacokinetics , Quinazolines/chemistry , Quinazolines/pharmacokinetics , Quinazolines/pharmacology , Rats, Nude , Treatment Outcome , Xenograft Model Antitumor Assays
10.
Angew Chem Int Ed Engl ; 55(6): 2007-11, 2016 Feb 05.
Article in English | MEDLINE | ID: mdl-26709952

ABSTRACT

A molecular Solomon link was synthesized in high yield through the template-free, coordination-driven self-assembly of a carbazole-functionalized donor and a tetracene-based dinuclear ruthenium(II) acceptor. The doubly interlocked topology was realized by a strategically chosen ligand which was capable of participating in multiple CH⋅⋅⋅π and π-π interactions, as evidenced from single-crystal X-ray analysis and computational studies. This method is the first example of a two-component self-assembly of a molecular Solomon link using a directional bonding approach. The donor alone was not responsible for the construction of the Solomon link, and was confirmed by its noncatenane self-assemblies obtained with other similar ruthenium(II) acceptors.

11.
J Appl Psychol ; 101(1): 108-21, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26052713

ABSTRACT

The multifoci perspective of justice proposes that individuals tend to target their (in)justice reactions toward the perceived source of the mistreatment. Empirical support for target-specific reactions, however, has been mixed. To explore theoretically relevant reasons for these discrepant results and address unanswered questions in the multifoci justice literature, the present research examines how different justice sources might interactively predict target-specific reactions, and whether these effects occur as a function of moral identity. Results from a sample of North American frontline service employees (N = 314, Study 1) showed that among employees with lower levels of moral identity, low supervisor justice exacerbated the association between low customer justice and customer-directed sabotage, whereas this exacerbation effect was not observed among employees with higher levels of moral identity. This 3-way interaction effect was replicated in a sample of South Korean employees (N = 265, Study 2).


Subject(s)
Employment/psychology , Morals , Organizational Culture , Social Justice , Adult , Female , Humans , Male , Personnel Management
12.
Int J Nanomedicine ; 10 Spec Iss: 143-53, 2015.
Article in English | MEDLINE | ID: mdl-26347134

ABSTRACT

Nano-sized multinuclear ruthenium complexes have rapidly emerged as promising therapeutic candidates with unique anticancer activities. Here, we describe the coordination-driven self-assembly and anticancer activities of a set of three organometallic tetranuclear Ru(II) molecular bowls. [2+2] Coordination-driven self-assembly of 3, 6-bis(pyridin-3- ylethynyl) phenanthrene (bpep) (1) and one of the three dinuclear arene ruthenium clips, [(η6-p-iPrC6H4Me)2Ru2-(OO\OO)][OTf]2 (OO\OO =2, 5-dioxido-1, 4-benzoquinonato, OTf = triflate) (2), 5, 8-dioxido-1, 4-naphthoquinonato (3), or 6, 11-dioxido-5, 12-naphthacenediona (4), resulted in three molecular bowls 5-7 of general formula [{(η6-p-iPrC6H4Me)2Ru2-(OO\OO)}2(bpep)2][OTf]4. All molecular bowls were obtained as triflate salts in very good yields (>90%) and were fully characterized using multinuclear nuclear magnetic resonance (NMR), electrospray ionization-mass spectrometry (ESI-MS), and elemental analysis. The structure of the representative molecular bowl 5 was confirmed by single-crystal X-ray diffraction analysis. The anticancer activities of molecular bowls 5-7 were determined by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide, autophagy, and Western blot analysis. Bowl 6 showed the strongest cytotoxicity in AGS human gastric carcinoma cells and was more cytotoxic than doxorubicin. In addition, autophagic activity and the ratio of apoptotic cell death increased in AGS cells by treatment with bowl 6. Bowl 6 also induced autophagosome formation via upregulation of p62 and promotion of the conversion of LC3-I to LC3-II. Moreover, bowl 6 promoted apoptotic cell death through downregulation of Akt/mTOR activation, followed by increased caspase-3 activity. These results suggest that bowl 6 induces gastric cancer cell death via modulation of autophagy and apoptosis. Bowl 6 is a potent anticancer agent and a potential treatment for human gastric cancer that merits further study.


Subject(s)
Antineoplastic Agents , Nanostructures/chemistry , Phenanthrenes , Ruthenium , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Cell Line, Tumor , Humans , Phenanthrenes/chemistry , Phenanthrenes/pharmacology , Ruthenium/chemistry , Ruthenium/pharmacology
13.
Chem Commun (Camb) ; 51(21): 4492-5, 2015 Mar 14.
Article in English | MEDLINE | ID: mdl-25682749

ABSTRACT

A hollow iridium-cornered prismatic cage was self-assembled without the assistance of any template. The cage was found to be capable of encapsulating heteroguest's triplet in its perfect sized cavity, producing the first demonstration of quintuple structure by an octahedral metal cornered prismatic cage.


Subject(s)
Coordination Complexes/chemistry , Iridium/chemistry , Crystallography, X-Ray , Magnetic Resonance Spectroscopy , Molecular Conformation , Nanostructures/chemistry , Particle Size
14.
Dalton Trans ; 43(16): 6032-40, 2014 Apr 28.
Article in English | MEDLINE | ID: mdl-24390643

ABSTRACT

A new dipyridyl ligand is encoded with 120° angularity between its coordination vectors by using a central pyridine carboxamide scaffold to orient two 4-(pyridin-4-ylethynyl)phenyl moieties. The N,N'-bis(4-(pyridin-4-ylethynyl)phenyl)pyridine-2,6-dicarboxamide ligand undergoes self-assembly with a diruthenium arene complex to furnish a [2 + 2] metallacycle with a wedge-like structure. The metallacycle binds to the enhanced green fluorescent protein (EGFP) variant of GFP, resulting in steady-state spectral changes in UV-Vis absorption and emission experiments. These studies indicate that the metallacycle induces conformation changes to the EGFP, disrupting the tripeptide chromophore. Furthermore, gel electrophoresis, circular dichroism and atomic force microscopy studies indicate that binding ultimately leads to aggregation of the protein. Computational investigations indicate a favorable interaction, predominantly between the metallacycle and the Arg168 residue of the EGFP. An interaction with Arg168 and related residues was previously observed for an emission-attenuating antibody, supporting that these interactions induce changes to the photophysical properties of EGFP by disrupting the tripeptidechromophore in a similar manner. Additionally, we have also described the quenching study of the reporter GFP protein in vivo by a new metal complex using reflected fluorescence microscopy. We anticipate that such metal complexes which can passively diffuse into the cells in vivo can serve as potential tools in molecular and drug targeting based biological studies.


Subject(s)
Coordination Complexes/chemistry , Green Fluorescent Proteins/chemistry , Ruthenium/chemistry , Biosensing Techniques , Circular Dichroism , Escherichia coli/genetics , Escherichia coli/metabolism , Green Fluorescent Proteins/metabolism , Microscopy, Atomic Force , Models, Molecular , Protein Binding
15.
J Nanosci Nanotechnol ; 13(6): 4325-9, 2013 Jun.
Article in English | MEDLINE | ID: mdl-23862495

ABSTRACT

The periodic beveled micro-rods (BMRs) were constructed on the emission surface of GaN-based vertical light-emitting diodes (VLEDs) in order to improve the light-extraction efficiency. It was experimentally demonstrated that the light output power of the VLEDs with a periodic BMR (BMR-VLED) were enhanced about 15.6%, compared with that of the VLEDs with randomly textured surface (RT-VLED) at an injection current of 350 mA. This finding indicates that the photons emitted from the active layer were well out-coupled at an n-GaN surface having a periodic BMR structure, resulting in an increase in the probability of escaping from the VLED structure.

16.
J Nanosci Nanotechnol ; 13(5): 3645-9, 2013 May.
Article in English | MEDLINE | ID: mdl-23858920

ABSTRACT

In this study, we have fabricated 375-nm-wavelength InGaN/AlInGaN nanopillar light emitting diodes (LED) structures on c-plane sapphire. A uniform and highly vertical nanopillar structure was fabricated using self-organized Ni/SiO2 nano-size mask by dry etching method. To minimize the dry etching damage, the samples were subjected to high temperature annealing with subsequent chemical passivation in KOH solution. Prior to annealing and passivation the UV nanopillar LEDs showed the photoluminescence (PL) efficiency about 2.5 times higher than conventional UV LED structures which is attributed to better light extraction efficiency and possibly some improvement of internal quantum efficiency due to partially relieved strain. Annealing alone further increased the PL efficiency by about 4.5 times compared to the conventional UV LEDs, while KOH passivation led to the overall PL efficiency improvement by more than 7 times. Combined results of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) suggest that annealing decreases the number of lattice defects and relieves the strain in the surface region of the nanopillars whereas KOH treatment removes the surface oxide from nanopillar surface.


Subject(s)
Lighting/instrumentation , Luminescent Measurements/instrumentation , Nanostructures/chemistry , Nanostructures/ultrastructure , Semiconductors , Desiccation/methods , Equipment Design , Equipment Failure Analysis , Particle Size , Ultraviolet Rays
17.
Opt Express ; 21(6): 7125-30, 2013 Mar 25.
Article in English | MEDLINE | ID: mdl-23546094

ABSTRACT

We have demonstrated the enhancement of a GaN-based light emitting diode (LED) by means of a selective etching technique. A conventional LED structure was periodically etched, to form periodic microholes. It showed an improvement of the light extraction efficiency (LEE) of approximately 15%, compared to that of a conventional LED. Furthermore, nano-sized rods inside the microholes were randomly formed by using a powder mask, resulting in an LEE of 43%. From the result of confocal scanning electroluminescence measurement, the light emission arises mainly from the vicinity of the nanorods in the periodic microholes. Therefore, we found that nanorods randomly distributed in periodic microholes in a LED structure play a significant role in the reduction of total internal reflection, by acting as photon wave-guides and scattering centers. This method would be valuable for the fabrication of high efficiency GaN-based LED, in terms of technical simplification and cost.


Subject(s)
Gallium/chemistry , Lighting/instrumentation , Nanotechnology/instrumentation , Nanotubes/chemistry , Semiconductors , Surface Plasmon Resonance/instrumentation , Energy Transfer , Equipment Design , Equipment Failure Analysis
18.
Opt Express ; 21(5): 6353-9, 2013 Mar 11.
Article in English | MEDLINE | ID: mdl-23482205

ABSTRACT

We demonstrated improved luminous efficacy for GaN-based vertical light emitting diodes (VLEDs) employing a low index layer composed of silicon dioxide (SiO(2)) on the top surface. Three-dimensional ðnite-difference time-domain simulations for the fabricated VLED chip show that the penetration ratio of the emitted/reflected light into the VLED chip decreased by approximately 20% compared to a normal VLED chip. This result is in good agreement with an empirical study stating that white VLEDs having a SiO(2) layer exhibit an 8.1% higher luminous efficacy than white VLEDs with no layer at an injection current of 350 mA. Photons penetrating into the VLED chip, which become extinct in the VLED chip, are reflected from the SiO(2) layer due to the index contrast between the SiO(2) layer and epoxy resin containing phosphor, with no degradation of the light-extraction efficiency of the VLED chip. As such, this structure can contribute to the enhancement of the luminous efficacy of VLEDs.

19.
Sci Transl Med ; 4(128): 128ra39, 2012 Apr 04.
Article in English | MEDLINE | ID: mdl-22491949

ABSTRACT

We describe the development and clinical translation of a targeted polymeric nanoparticle (TNP) containing the chemotherapeutic docetaxel (DTXL) for the treatment of patients with solid tumors. DTXL-TNP is targeted to prostate-specific membrane antigen, a clinically validated tumor antigen expressed on prostate cancer cells and on the neovasculature of most nonprostate solid tumors. DTXL-TNP was developed from a combinatorial library of more than 100 TNP formulations varying with respect to particle size, targeting ligand density, surface hydrophilicity, drug loading, and drug release properties. Pharmacokinetic and tissue distribution studies in rats showed that the NPs had a blood circulation half-life of about 20 hours and minimal liver accumulation. In tumor-bearing mice, DTXL-TNP exhibited markedly enhanced tumor accumulation at 12 hours and prolonged tumor growth suppression compared to a solvent-based DTXL formulation (sb-DTXL). In tumor-bearing mice, rats, and nonhuman primates, DTXL-TNP displayed pharmacokinetic characteristics consistent with prolonged circulation of NPs in the vascular compartment and controlled release of DTXL, with total DTXL plasma concentrations remaining at least 100-fold higher than sb-DTXL for more than 24 hours. Finally, initial clinical data in patients with advanced solid tumors indicated that DTXL-TNP displays a pharmacological profile differentiated from sb-DTXL, including pharmacokinetics characteristics consistent with preclinical data and cases of tumor shrinkage at doses below the sb-DTXL dose typically used in the clinic.


Subject(s)
Antigens, Surface/metabolism , Glutamate Carboxypeptidase II/metabolism , Nanoparticles/chemistry , Taxoids/pharmacology , Taxoids/pharmacokinetics , Animals , Cell Line, Tumor , Docetaxel , Humans , Male , Mice , Nanoparticles/administration & dosage , Polymers/chemistry , Rats , Taxoids/administration & dosage , Taxoids/chemistry , Xenograft Model Antitumor Assays
20.
Dalton Trans ; 41(10): 3046-52, 2012 Mar 14.
Article in English | MEDLINE | ID: mdl-22278716

ABSTRACT

A suite of eight cationic, tetra-metallic molecular rectangles (1-8) was generated via coordination-driven self-assembly using four dicarboxylate-bridged arene-Ru precursors (A1-A4) with one of two dipyridyl ligands (D1, D2). The high-yielding (84-92%) rectangles were characterized by (1)H NMR and HR-ESI-MS to support their structural assignments. The molecular structure of 5 was determined by single crystal X-ray analysis, which indicated that two D2 ligands bridge two A1 acceptors to form a rectangular construct. The photophysical properties of these metalla-rectangles and their molecular precursors were also investigated, as well as an MTT assay to evaluate the in vitro cytotoxicities relative to two chemotherapeutic agents, cisplatin and doxorubicin. MTT assays were conducted using SK-hep-1 (liver cancer) and HCT-15 (colon cancer) human cancer cell lines. Compounds 3, 4, 7 and 8 showed significant activity, with IC(50) values comparable to those of cisplatin and doxorubicin.


Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Organometallic Compounds/chemistry , Organometallic Compounds/pharmacology , Ruthenium/chemistry , Antineoplastic Agents/chemical synthesis , Cell Line, Tumor , Electrons , Humans , Inhibitory Concentration 50 , Models, Molecular , Molecular Conformation , Organometallic Compounds/chemical synthesis , Spectrometry, Fluorescence , Spectrophotometry, Ultraviolet
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