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- ArticleSelman C, Sinclair A, Pedroni SM, Irvine EE, Michie AM, Withers DJ.Oncotarget. 2016 May 24;7(21):29937-43.The mechanistic target of rapamycin (mTOR) signalling pathway plays a highly conserved role in aging; mice lacking ribosomal protein S6 kinase 1 (S6K1-/-) have extended lifespan and healthspan relative to wild type (WT) controls. Exactly how reduced mTOR signalling induces such effects is unclear, although preservation of stem cell function may be important. We show, using gene expression analyses, that there was a reduction in expression of cell cycle genes in young (12 week) and aged (80 week) S6K1-/- BM-derived c-Kit+ cells when compared to age-matched WT mice, suggesting that these cells are more quiescent in S6K1-/- mice. In addition, we investigated hematopoietic stem cell (HSC) frequency and function in young and aged S6K1-/-and WT mice. Young, but not aged, S6K1-/-mice had more LSK (lineage-, c-Kit+, Sca-1+) cells (% of bone marrow (BM)), including the most primitive long-term repopulating HSCs (LT-HSC) relative to WT controls. Donor-derived engraftment of LT-HSCs in recipient mice was unaffected by genotype in young mice, but was enhanced in transplants using LT-HSCs derived from aged S6K1-/- mice. Our results are the first to provide evidence that age-associated HSC functional decline is ameliorated in a long-lived mTOR mutant mouse.
- ArticleFokam J, Takou D, Semengue ENJ, Molimbou E, Chenwi Ambe C, Durand Nka A, Ndjeyep SD, ... Show More Beloumou GA, Ka'e CA, Gouissi Anguechia DH, Mundo Nayang AR, Moko Fotso LG, Kengni Ngueko AM, Etame NK, Tueguem PP, Tommo Tchouaket CM, Fainguem N, Abega Abega C, Abba A, Tambe Ayuk Ngwese D, Djubgang Djoukwe R, Akenji B, Okomo Assoumou MC, Mandeng N, Esso L, Cappelli G, Shang J, Ndongmo C, Etoundi Mballa GA, Ndembi N, Colizzi V, Perno CF, Ndjolo A.Heliyon. 2024 May 15;10(9):e29937.Background: WHO recommends the use of COVID-19 antigen rapid diagnostic tests (Ag-RDT) with at least 80 % sensitivity and 97 % specificity. In the era of Omicron variants, we sought to ascertain the performance of the INDICAID™ Ag-RDT compared to real-time PCR (RT-PCR) as the gold standard.
Methods: A laboratory-based study was conducted among consenting individuals tested for COVID-19 at the virology laboratory of the Chantal BIYA International Reference Centre, Yaoundé-Cameron. The samples were processed by INDICAID™ Ag-RDT and DaAn Gene real-time PCR according to the manufacturer's instructions, and PCR-results were interpreted as per cycle thresholds (CT). The sensitivity, specificity, positive and negative predictive values (PPV and NVP) of INDICAID™ Ag-RDT were evaluated according to PCR CT-values.
Results: A total of 565 nasopharyngeal swabs were collected from participants (median age [IQR]: 40 [31-75]; M/F sex-ratio was 1.2 and 380 were vaccinated). Following PCR, overall COVID-19 positivity was 5.66 %. For CT < 37, INDICAID™ Ag-RDT sensitivity was 21.9 % (95%CI: [8.3-39.9]), specificity 100 % (95%CI: [99.3-100]); PPV 100 % (95%CI: [59.0-100]), NPV 95.5 % (95%CI: [93.4-97.1]) and kappa = 0.34 (95%CI: [0.19-0.35]). For CT < 25, sensitivity was 100 % (95%CI: [47.8-100.0]), specificity 99.6 % (95%CI: [98.7-99.9]); PPV 94.4 % (95%CI: [51.7-100]), NPV 100 % (95%CI: [99.3-100]) and kappa = 0.83 (95%CI: [0.6-1.0]). COVID-19 sequences generated were all Omicron BA.1 subvariants.
Conclusion: For patients infected with high viral loads (CT < 25), INDICAID™ Ag-RDT has high intrinsic (sensitivity and specificity) and extrinsic (predictive values) performances for COVID-19 diagnosis. Due to its simplicity and short turnaround time, INDICAID™ Ag-RDT is, therefore a reliable tool to prevent the spread of COVID-19 at community level in the current era of Omicron subvariants. - ArticleCivlan S, Harvey C, Herek D, Türkçüer İ, Sabirli R, Pellegrini M, Koseler A.Cureus. 2022 Oct;14(10):e29937.Hypertrophic pachymeningitis (HP) is a rare clinical entity of diverse etiology, characterized by a chronic inflammation that causes dura thickening. Reports of Idiopathic hypertrophic cranial pachymeningitis (IHCP) were related to infections, trauma, tumors, and rheumatologic conditions. It was first described by Charcot and Joffroy regarding spinal meninges in 1869. HP has three stages; progressive radicular symptoms begin first, then muscle weakness and atrophy start. Findings such as paraplegia, loss of bladder and bowel control, and respiratory distress caused by intercostal and diaphragmatic denervation are considered the third stage of the disease. Especially in the cranial form of the disease, nerve ischemia and various cranial neuropathic findings may occur. Factor V Leiden (G1691A), MTHFR C677T, MTHFR A1298C, and PAI-1 4G-5G gene mutation analysis were measured with an ABI Prism. In this case report, the authors present a case of hypertrophic mutations pachymeningitis with Factor V Leiden (G1691A), MTHFR C677T, MTHFR A1298C, PAI-1 4G-5G, Glycoprotein IIIa L33P gene. In conclusion, we report a case of HP with Factor V Leiden (G1691A), MTHFR C677T, MTHFR A1298C, PAI-1 4G-5G, and Glycoprotein IIIa L33P gene mutations. We emphasize that the identification of pachymeningitis can be easily bypassed with the application of limited laboratory techniques. As in this case report, we think that these mutations should be analyzed in patients diagnosed with pachymeningitis.
- ArticleCastanié A, Mercier JF, Félix S, Maurel A.Opt Express. 2014 Dec 01;22(24):29937-53.Electromagnetic or acoustic metamaterials can be described in terms of equivalent effective, in general anisotropic, media and several techniques exist to determine the effective permeability and permittivity (or effective mass density and bulk modulus in the context of acoustics). Among these techniques, retrieval methods use the measured reflection and transmission coefficients (or scattering coefficients) for waves incident on a metamaterial slab containing few unit cells. Until now, anisotropic effective slabs have been considered in the literature but they are limited to the case where one of the axes of anisotropy is aligned with the slab interface. We propose an extension to arbitrary orientations of the principal axes of anisotropy and oblique incidence. The retrieval method is illustrated in the electromagnetic case for layered media, and in the acoustic case for array of tilted elliptical particles.
- ArticleZhu Q, Sun X, Ji X, Zhu L, Xu J, Wang C, Zhang C, Xue F, Liu Y.Sci Rep. 2016 07 22;6:29937.The precise association between metabolic syndrome (MetS) and gallstone disease remains unclear in China. This study aimed to clarify the relationship between MetS and gallstone and evaluate whether counts of metabolic abnormalities had influence on gallstone disease. We fitted gender-specific generalized estimating equation (GEE) regression models with data from a large-scale longitudinal study over 6-year follow-up to elucidate the real association. This study included 18291 participants with 3 times repeated measures at least who were free from a prior history of gallstone disease and cholecystectomy. A total of 873 cases of gallstones occurred during 6-year follow-up. The incidence density of gallstone in the group of subjects with MetS was higher than the group without MetS (10.27 vs 5.79). The GEE analyses confirmed and clarified the association between MetS and gallstone disease in males (RR = 1.33, P = 0.0020), while this association was not significant in females (RR = 1.15, P = 0.4962). With numbers of metabolic syndrome components increasing, the risk of gallstone disease showed corresponding increasing in males. In conclusion, the associations of MetS and gallstone are different in males and in females. And the risk of gallstone disease increases with the number of components of MetS for males but not for females.
- ArticleAbdulla A, Zhang Y, Hsu FN, Xiaoli AM, Zhao X, Yang ES, Ji JY, Yang F.J Biol Chem. 2014 Oct 24;289(43):29937-47.Dysregulation of lipid homeostasis is a common feature of several major human diseases, including type 2 diabetes and cardiovascular disease. However, because of the complex nature of lipid metabolism, the regulatory mechanisms remain poorly defined at the molecular level. As the key transcriptional activators of lipogenic genes, such as fatty acid synthase (FAS), sterol regulatory element-binding proteins (SREBPs) play a pivotal role in stimulating lipid biosynthesis. Several studies have shown that SREBPs are regulated by the NAD(+)-dependent histone deacetylase SIRT1, which forms a complex with the lysine-specific histone demethylase LSD1. Here, we show that LSD1 plays a role in regulating SREBP1-mediated gene expression. Multiple lines of evidence suggest that LSD1 is required for SREBP1-dependent activation of the FAS promoter in mammalian cells. LSD1 knockdown decreases SREBP-1a at the transcription level. Although LSD1 affects nuclear SREBP-1 abundance indirectly through SIRT1, it is also required for SREBP1 binding to the FAS promoter. As a result, LSD1 knockdown decreases triglyceride levels in hepatocytes. Taken together, these results show that LSD1 plays a role in regulating lipogenic gene expression, suggesting LSD1 as a potential target for treating dysregulation of lipid metabolism.
- ArticleCassie H, Duncan EM, Gibb EA, Power A, Young L, Newlands R, Watson MC.BMJ Open. 2019 08 15;9(8):e029937.OBJECTIVES: Gathering relevant patient information during over-the-counter (OTC) consultations increases the likelihood of safe, effective and person-centred outcomes. The aim of this study was to explore the key determinants to information gathering during consultations for non-prescription medicine requests in community pharmacies in Scotland.
DESIGN: Semi-structured interviews using the Theoretical Domains Framework (TDF), with community pharmacy teams across Scotland. Interviews explored participants' knowledge of current guidance, skills required to elicit information and barriers and facilitators associated with this behaviour. Theory-based content analysis was undertaken using the TDF as an initial coding framework to identify key determinants and map them to salient domains. Salience was determined by prominence or variation in views. Comparative analysis was undertaken by professional role.
RESULTS: Thirty interviews were conducted with pharmacists (n=19) and medicine counter assistants (MCAs) (n=11). Eight salient domains were identified: environmental context and resources (privacy), beliefs about consequences (patient safety), skills (communication, decision-making), social influences (patient awareness of pharmacist role), knowledge (awareness and use of standard operating procedures), social professional role and identity (perception of own role), behavioural regulation (training) and intention (to gather information). Similar domains were salient for pharmacists and MCAs; however, different beliefs were associated with different roles. Overarching themes were identified: best practice, health literacy, decision-making and professionalism.
CONCLUSIONS: Multiple influences and complexities affect the effective management of OTC consultations. While similar factors impact on both pharmacists and MCAs at a patient, professional and environmental level, subtle differences exist in how these influence their management of OTC consultations. This study highlights the importance of tailoring interventions to reflect different roles, functions and responsibilities of community pharmacy personnel. - ArticleLee SH, Joo NS.Medicine (Baltimore). 2022 Aug 19;101(33):e29937.It is known that ultraviolet B exposure increases serum 25-hydroxyvitamin D(25(OH)D) concentrations. However, little is known about the influence of narrowband ultraviolet B exposure from a light-emitting diode (NBUVB-LED) on serum 25(OH)D levels. Thus, the purpose of this study was to investigate the effect of NBUVB-LED exposure on serum 25(OH)D concentrations. Two healthy adults were enrolled in this pilot study. Their skin was exposed to ultraviolet B light (60 mJ/cm2) 3 times a week for 4 weeks in the first intervention and every day for 4 weeks in the second intervention. Serum levels of 25(OH)D were measured every 2 weeks. Serum 25(OH)D levels were decreased in both subjects at the end of the first intervention (32.1 → 21.4 ng/mL, 33.9 → 21.4 ng/mL, respectively), whereas serum 25(OH)D levels were increased in the 2 weeks of the second intervention (29.5 and 28.0 ng/mL, respectively). At the end of the second intervention, the 25(OH)D concentrations were 19.0 and 20.4 ng/mL, respectively. NBUVB-LED exposure might increase serum 25(OH)D concentrations. Future studies should expand the number of participants and adjust for confounding factors.
- ArticleElgarten CW, Thompson JC, Angiolillo A, Chen Z, Conway S, Devidas M, Gupta S, Kairalla JA, McNeer JL, O'Brien MM, Rabin KR, Rau RE, Rheingold SR, Wang C, Wood C, Raetz EA, Loh ML, Alexander S, Miller TP.Pediatr Blood Cancer. 2022 11;69(11):e29937.Infections cause substantial morbidity for children with acute lymphoblastic leukemia (ALL). Therefore, accurate characterization of infectious adverse events (AEs) reported on clinical trials is imperative to defining, comparing, and managing safety and toxicity. Here, we describe key processes implemented to improve reporting of infectious AEs on two active phase III Children's Oncology Group (COG) ALL trials. Processes include: (a) identifying infections as a targeted toxicity, (b) incorporation of infection-specific case report form questions, and (c) physician review of AEs with real-time data cleaning. Preliminary assessment of these processes suggests improved reporting, as well as opportunities for further improvement.
- ArticleFukunaga R, Yokoyama S.J Biol Chem. 2005 Aug 19;280(33):29937-45.The editing domain of valyl-tRNA synthetase (ValRS) is known to deacylate, or edit, misformed Thr-tRNA(Val) (post-transfer editing). Here, we determined the 1.7-Angstroms resolution crystal structure of the Thermus thermophilus ValRS editing domain. A comparison of the structure with the previously reported tRNA complex structure revealed conformational changes of the editing domain upon accommodation of the terminal A76; the "GTG loop" moves to expand the pocket, and the side chain of Phe-264 on the GTG loop rotates to interact with the A76 adenine ring. If these conformational changes did not occur, then C75 and A76 of the tRNA would clash with Phe-264. To elucidate the mechanism of the threonine side-chain recognition, we determined the crystal structure of the editing domain bound with [N-(L-threonyl)-sulfamoyl]adenosine at 1.7-Angstroms resolution. The gamma-OH of the threonyl moiety is recognized by the Lys-270, Thr-272, and Asp-279 side chains, which may reject the cognate valyl moiety. Accordingly, ValRS mutants with an Ala substitution for Lys-270 or Asp-279 synthesized significant amounts of Thr-tRNA(Val). The misproduced Thr-tRNA(Val) was hydrolyzed efficiently by the wild-type ValRS, but this post-transfer editing activity was drastically impaired by the Ala substitutions for Lys-270 and Asp-279 and was also decreased by those for Arg-216, Phe-264, and Thr-272. These results indicate that the threonyl moiety and A76 of Thr-tRNA(Val) are recognized by the Lys-270, Thr-272, and Asp-279 side chains and by the Phe-264 side chain, respectively, of the ValRS editing domain.
- ArticleSung YJ, Kim MS, Kim H, Choi S, Kim YH, Jung MH, Choi RJ, Moon YT, Oh JT, Jeong HH, Yeom GY.Opt Express. 2019 Oct 14;27(21):29930-29937.AlGaN-based vertical type high power ultraviolet-C light emitting diodes (UV-C LEDs), which have a Ga-face n-contact structure, were fabricated on a LED epilayer transferred to a carrier wafer through a laser lift-off (LLO) process. A significant light extraction enhancement of the vertical chip by using a highly reflective ITO/Al p-type electrode is demonstrated, along with surface roughening. A GaN-free LED epi structure is employed to prevent light absorption in the UV-C wavelength region. The vertical chip with the ITO/Al reflector and n-AlGaN surface roughening exhibited a high light output power of 104.4mW with a peak wavelength of 277.6nm at an injection current of 350mA. Comparing the device characteristics of the vertical chip and the flip chip showed that the light output power of the vertical chip was 1.31 times higher than that of the flip chip at 350mA. In particular, with the high power vertical type UV-C LED, a maximum light output power of 630mW could be achieved at a current of 3.5A, and this is mainly attributed to efficient heat dissipation through a metal substrate and the resulting relatively lower junction temperature of the vertical chip.
- ArticleZalewski A, Cecchini EL, Deroo BJ.PLoS One. 2012;7(1):e29937.Within the ovary, Estrogen Receptor β (ERβ) is localized to the granulosa cells of growing follicles. 17β-estradiol (E2) acting via ERβ augments the actions of follicle stimulating hormone in granulosa cells, leading to granulosa cell differentiation and formation of a preovulatory follicle. Adult ERβ-null females are subfertile and possess ovaries with reduced numbers of growing follicles and corpora lutea. Because the majority of E2 production by granulosa cells occurs once puberty is reached, a role for ERβ in the ovary prior to puberty has not been well examined. We now provide evidence that lack of ERβ disrupts gene expression as early as post-natal day (PND) 13, and in particular, we identify a number of genes of the extracellular matrix (ECM) that are significantly higher in ERβ-null follicles than in wildtype (WT) follicles. Considerable changes occur to the ECM occur during normal folliculogenesis to allow for the dramatic growth, cellular differentiation, and reorganization of the follicle from the primary to preovulatory stage. Using quantitative PCR and immunofluorescence, we now show that several ECM genes are aberrantly overexpressed in ERβ-null follicles. We find that Collagen11a1, a protein highly expressed in cartilage, is significantly higher in ERβ-null follicles than WT follicles as early as PND 13, and this heightened expression continues through PND 23-29 into adulthood. Similarly, Nidogen 2, a highly conserved basement membrane glycoprotein, is elevated in ERβ-null follicles at PND 13 into adulthood, and is elevated specifically in the ERβ-null focimatrix, a basal lamina-like matrix located between granulosa cells. Focimatrix laminin and Collagen IV expression were also higher in ERβ-null ovaries than in WT ovaries at various ages. Our findings suggest two novel observations: a) that ERβ regulates granulosa cell gene expression ovary prior to puberty, and b) that ERβ regulates expression of ECM components in the mouse ovary.
- ArticleKim HT, Hwang W, Liu Y, Yu M.Opt Express. 2020 Sep 28;28(20):29937-29947.Refractive-index (RI)-based sensing is a major optical sensing modality that can be implemented in various spectral ranges. While it has been widely used for sensing of biochemical liquids, RI-based gas sensing, particularly small-molecule gases, is challenging due to the extremely small RI change induced by gas concentration variations. We propose a RI-based ultracompact fiber-optic differential gas sensor that employs metal-organic-framework (MOF)-based dual Fabry-Perot (FP) nanocavities. A MOF is used as the FP cavity material to enhance the sensitivity as well as the selectivity to particular gas molecules. The differential sensing scheme leverages the opposite change in the cavity-length-dependent reflection of the two FP cavities, which further enhances the sensitivity compared with single FP cavity based sensing. For proof-of-concept, a fiber-optic CO2 sensor with ZIF-8-based dual FP nanocavities was fabricated. The effective footprint of the sensor was as small as 157 µm2 and the sensor showed an enhanced sensitivity of 48.5 mV/CO2Vol%, a dynamic range of 0-100 CO2Vol%, and a resolution of 0.019 CO2Vol% with 1 Hz low-pass filtering. Although the current sensor was only demonstrated for CO2 sensing, the proposed sensor concept can be used for sensing of a variety of gases when different kinds of MOFs are utilized.
- ArticleDanilkovitch A, Miller M, Leonard EJ.J Biol Chem. 1999 Oct 15;274(42):29937-43.Macrophage-stimulating protein (MSP) and hepatocyte growth factor/scatter factor (HGF/SF) are plasminogen-related growth and motility factors that interact with cell-surface protein tyrosine kinase receptors. Each one is a heterodimeric protein comprising a disulfide-linked alpha chain and a serine protease-like beta chain. Despite structural similarities between MSP and HGF, the primary receptor binding site is located on the alpha chain of HGF/SF but on the beta chain of MSP. To obtain insight into the structural basis for MSP beta chain binding, beta chain structure was modeled from coordinates of an existing model of the HGF beta chain. The model revealed that the region corresponding to the S1 specificity pocket in trypsin is filled by the Asn(682)/Glu(648) interacting pair, leaving a shallow cavity for possible beta chain interaction with the receptor. Mutants in this region were created, and their binding characteristics were determined. A double mutation of Asn(682)/Glu(648) caused diminished binding of the beta chain to the MSP receptor, and a single mutation of neighboring Arg(683) completely abolished binding. Thus, this region of the molecule is critical for binding. We also found that at equimolar concentrations of free alpha and beta chains, alpha chain binding to receptor was detectable, at levels considerably lower than beta chain binding. The EC(50) values determined by quantitative enzyme-linked immunosorbent assay are 0.25 and 16.9 nM for beta and alpha chain, respectively. The data suggest that MSP has two independent binding sites with high and low affinities located in beta and alpha chain, respectively, and that the two sites together mediate receptor dimerization and subsequent activation.
- ArticleLiu Q, Levy EJ, Chirico WJ.J Biol Chem. 1996 Nov 22;271(47):29937-44.Hsp70 molecular chaperones are ATPases that bind to hydrophobic regions of proteins and guide their folding, assembly, and translocation across membranes. The ability of purified Hsp70s to uncoat clathrin-coated vesicles or to stimulate the post-translational translocation of precursor proteins into the endoplasmic reticulum, mitochondria, and the nucleus was previously shown not to be sensitive to the sulfhydryl-modifying reagent N-ethylmaleimide (NEM). During purification of factors required for protein folding in the cytosol, we found that the ATP-agarose binding activity of the yeast Hsp70 Ssa1p in postribosomal supernatants was inhibited by NEM. We also found that completely removing nucleotides from purified Ssa1p rendered its ATP-agarose binding activity, ATPase activity, and post-translational translocation-stimulating activity sensitive to NEM. We modified nucleotide-free Ssa1p with [14C]NEM and then digested it with proteases. Purification and sequencing of the radiolabeled proteolytic fragments revealed that each of Ssa1p's three cysteine residues (Cys-15, Cys-264, and Cys-303) was modified with [14C]NEM. ADP protected each of the cysteine residues from modification and protected Ssa1p from inactivation. The cysteine residues are the reactive centers of three NEM-reactive sites (NRS1-3). A comparison of Ssa1p's NRSs to sequences of other Hsp70s and actin revealed that Cys-15 of NRS1 is highly conserved and that sensitivity to NEM may be a property of many Hsp70s. Based on the three-dimensional structure of Hsc70, the predicted locations of Ssa1p's cysteine residues suggest that NEM may disrupt the conformation of Ssa1p or interfere with its ability to bind nucleotides. Together the results demonstrate that Ssa1p is an NEM-sensitive factor in cytosolic extracts from yeast that stimulates post-translational translocation of proteins into organelles.
- ArticleBMJ Open. 2019 Sep 03;9(8):e029937corr1.
- ArticleFerguson RP.J Community Hosp Intern Med Perspect. 2015;5(6):29937.
- ArticleKirikkaleli D, Oyebanji MO.Environ Sci Pollut Res Int. 2022 Apr;29(20):29927-29937.The consequences of global trade on carbon dioxide emissions have been mainly investigated in several empirical papers; however, the consumption-based carbon emissions adjusted for international trade have been lacking in the literature. This empirical research seeks to address this gap by using consumption-based carbon emissions adjusted for trade in the case of Bolivia. Research over the years shows that Bolivia has had a consistent negative trade deficit which suggests that there might be a rise in consumption-based emission in this area in the present and the future. It also indicates that considerable emissions are attributable to the consumption of commodities and services transferred to Bolivia, which is beyond its control. Many studies, however, have delved into the production-based carbon emission for Bolivia. However, the consumption-based carbon emission adjusted for international trade has been missing in the case of Bolivia. Meanwhile, failure to recognize these emissions related to international trade produces an incomplete picture of the emissions triggers and the effectiveness of action to lessen emissions in this area. Hence, this study attempts to fill the gap. The impact of exports and imports are analyzed separately for 1970 to 2018. The empirical analysis confirms a negative effect of exports and GDP on consumption-based carbon emissions. In comparison, imports and globalization demonstrate a favorable impact on consumption-based carbon emissions and show their statistical significance. This study suggests that the Bolivia government should be cautious on policies targeted at increasing growth as this could be harmful to the sustainability of the environment.
- ArticleChen Z, Xie Q, Ding J, Yang Z, Zhang W, Cheng H.ACS Appl Mater Interfaces. 2020 Jul 01;12(26):29937-29945.Direct printing of transparent conducting oxide (TCO) nanocrystal dispersions holds great promise in solution-processed optoelectronics due to its advantages of low material waste and direct patterning on substrates. An essential prerequisite for printable TCO colloidal solutions is the effective stabilization of TCO nanocrystals to prevent their strong aggregation. In situ stabilization uses long-chain ligands to provide interparticle steric repulsion between TCO nanocrystals during the growth of TCO nanocrystals. In sharp contrast, the postsynthesis dispersion of TCO nanocrystals is particularly challenging since the agglomeration already occurs, especially for TCO nanocrystals synthesized without protection by any organic species. Herein, we propose an instant postsynthesis strategy for aqueous colloidal dispersions of Sb-doped SnO2 (ATO) nanocrystals using small-molecule amines of propylamine, ethylenediamine, monoethanolamine, and triethylamine. The average size of ATO secondary particles in aqueous dispersions can be instantly reduced from around 400 to about 25 nm using these amines. The increased Sb dopant ratio also plays a synergistic role in the dispersion effect. The small-molecule amines are found to be preferably adsorbed onto the Sb sites exposed on ATO nanocrystal surface. A higher Sb dopant ratio would facilitate the adsorption of more amines and induce stronger surface charge repulsion that benefits the stable dispersion of ATO nanocrystals. TCO films fabricated with the ATO nanocrystal dispersions have a high transparency of 80.6% and low sheet resistance of 492 Ω/sq, showing promising application in electrochromic devices.
- ArticleKassu A, Farley C, Sharma A, Kim W, Guo J.Sensors (Basel). 2015 Nov 30;15(12):29924-37.A sensitive surface enhanced Raman scattering chemical sensor is demonstrated by using inexpensive gold-coated nanoporous anodic aluminum oxide substrates. To optimize the performance of the substrates for sensing by the Surface-enhanced Raman scattering (SERS) technique, the size of the nanopores is varied from 18 nm to 150 nm and the gold film thickness is varied from 30 nm to 120 nm. The sensitivity of gold-coated nanoporous surface enhanced Raman scattering sensor is characterized by detecting low concentrations of Rhodamine 6G laser dye molecules. The morphology of the SERS substrates is characterized by atomic force microscopy. Optical properties of the nanoporous SERS substrates including transmittance, reflectance, and absorbance are also investigated. Relative signal enhancement is plotted for a range of substrate parameters and a detection limit of 10(-6) M is established.