MR and CT angiography in the diagnosis of vasculitides.

Vasculitides represent the wide-ranging series of complex inflammatory diseases that involve inflammation of blood vessel walls. These conditions are characterized according to the caliber of the predominantly involved vessels. The work-up of vasculitides often includes imaging to narrow a differential diagnosis and guide management. Findings from CT and MR angiography in conjunction with a thorough history and physical exam are of utmost importance in making an accurate diagnosis. Further, imaging can be used for follow-up, in order to monitor disease progression and response to treatment. This wide-ranging literature review serves as the primary resource for clinicians looking to diagnose and monitor the progression of rare vascular inflammatory conditions. This article provides a comprehensive summary of the main findings on imaging related to each of these vasculitides. For each of the named vasculitis conditions, a thorough overview of the diagnostic modalities and their respective findings is described. Many specific hallmarks of pathology are included in this review article.

Evolving Trends in US Mortality from Opioid Overdose: Heroin and Beyond.

OBJECTIVE: Our objective was to explore evolving trends in US drug overdose mortality, overall and by age, sex, race, urbanization, and geography from 1999-2020. METHODS: This is a descriptive epidemiologic study. We used the US Centers for Disease Control and Prevention Wide-ranging Online Data for Epidemiologic Research and Multiple Cause of Death files from the National Center for Health Statistics. We used crude and age-adjusted cause of death and mortality rate ratios as measures of effects and 95% confidence limits to test for significance. RESULTS: From 1999-2020, drug overdoses caused 1,013,852 deaths and 4.3-fold increase in mortality rate ratios. Subgroup findings were sex (4.5 men, 4.0 women), race (4.6 White, 3.9 Black or African American, 4.0 Asian or Pacific Islanders, 5.1 Native Americans or Alaskan Natives), age (highest 5.6 in 25-34 years, lowest 1.1 in 75-84, and 0.77 in 85+), geography (highest 6.0 in Midwest, lowest 2.6 in West), and urbanization (highest 6.2 in non-metro, lowest 3.7 in metro). CONCLUSIONS: Drug overdoses in the United States from 1999-2020 increased 4.3-fold, with the highest increase in White and Native American or Alaskan Native populations, and Midwest and non-metro areas. The data create preventive and therapeutic challenges, including restrictions on pharmaceutical industries and enhanced efforts by health care providers in safer prescribing. Addiction care should be integrated into all clinical practices, regardless of specialty, and into undergraduate, graduate, and continuing medical education. Targeted interventions are needed to adequately assess patients and provide care. Analytic studies designed a priori are necessary to test hypotheses formulated from these data.

Interventions for waterpipe smoking cessation.

BACKGROUND: While cigarette smoking has declined globally, waterpipe smoking is rising, especially among youth. The impact of this rise is amplified by mounting evidence of its addictive and harmful nature. Waterpipe smoking is influenced by multiple factors, including appealing flavors, marketing, use in social settings, and misperceptions that waterpipe is less harmful or addictive than cigarettes. People who use waterpipes are interested in quitting, but are often unsuccessful at doing so on their own. Therefore, developing and testing waterpipe cessation interventions to help people quit was identified as a priority for global tobacco control efforts.  OBJECTIVES: To evaluate the effectiveness of tobacco cessation interventions for people who smoke waterpipes. SEARCH METHODS: We searched the Cochrane Tobacco Addiction Review Group Specialized Register from database inception to 29 July 2022, using variant terms and spellings ('waterpipe' or 'narghile' or 'arghile' or 'shisha' or 'goza' or 'narkeela' or 'hookah' or 'hubble bubble'). We searched for trials, published or unpublished, in any language. SELECTION CRITERIA: We sought randomized controlled trials (RCTs), quasi-RCTs, or cluster-RCTs of any smoking cessation interventions for people who use waterpipes, of any age or gender. In order to be included, studies had to measure waterpipe abstinence at a three-month follow-up or longer. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcome was abstinence from waterpipe use at least three months after baseline. We also collected data on adverse events. Individual study effects and pooled effects were summarized as risk ratios (RR) and 95% confidence intervals (95% CI), using Mantel-Haenszel random-effects models to combine studies, where appropriate. We assessed statistical heterogeneity with the I2 statistic. We summarized secondary outcomes narratively. We used the five GRADE considerations (risk of bias, inconsistency of effect, imprecision, indirectness, and publication bias) to assess the certainty of the body of evidence for our primary outcome in four categories high, moderate, low, or very low. MAIN RESULTS: This review included nine studies, involving 2841 participants. All studies were conducted in adults, and were carried out in Iran, Vietnam, Syria, Lebanon, Egypt, Pakistan, and the USA. Studies were conducted in several settings, including colleges/universities, community healthcare centers, tuberculosis hospitals, and cancer treatment centers, while two studies tested e-health interventions (online web-based educational intervention, text message intervention). Overall, we judged three studies to be at low risk of bias, and six studies at high risk of bias. We pooled data from five studies (1030 participants) that tested intensive face-to-face behavioral interventions compared with brief behavioral intervention (e.g. one behavioral counseling session), usual care (e.g. self-help materials), or no intervention. In our meta-analysis, we included people who used waterpipe exclusively, or with another form of tobacco. Overall, we found low-certainty evidence of a benefit of behavioral support for waterpipe abstinence (RR 3.19 95% CI 2.17 to 4.69; I2 = 41%; 5 studies, N = 1030). We downgraded the evidence because of imprecision and risk of bias. We pooled data from two studies (N = 662 participants) that tested varenicline combined with behavioral intervention compared with placebo combined with behavioral intervention. Although the point estimate favored varenicline, 95% CIs were imprecise, and incorporated the potential for no difference and lower quit rates in the varenicline groups, as well as a benefit as large as that found in cigarette smoking cessation (RR 1.24, 95% CI 0.69 to 2.24; I2 = 0%; 2 studies, N = 662; low-certainty evidence). We downgraded the evidence because of imprecision. We found no clear evidence of a difference in the number of participants experiencing adverse events (RR 0.98, 95% CI 0.67 to 1.44; I2 = 31%; 2 studies, N = 662). The studies did not report serious adverse events.   One study tested the efficacy of seven weeks of bupropion therapy combined with behavioral intervention. There was no clear evidence of benefit for waterpipe cessation when compared with behavioral support alone (RR 0.77, 95% CI 0.42 to 1.41; 1 study, N = 121; very low-certainty evidence), or with self-help (RR 1.94, 95% CI 0.94 to 4.00; 1 study, N = 86; very low-certainty evidence).  Two studies tested e-health interventions. One study reported higher waterpipe quit rates among participants randomized to either a tailored mobile phone or untailored mobile phone intervention compared with those randomized to no intervention (RR 1.48, 95% CI 1.07 to 2.05; 2 studies, N = 319; very low-certainty evidence). Another study reported higher waterpipe abstinence rates following an intensive online educational intervention compared with a brief online educational intervention (RR 1.86, 95% CI 1.08 to 3.21; 1 study, N = 70; very low-certainty evidence).  AUTHORS' CONCLUSIONS: We found low-certainty evidence that behavioral waterpipe cessation interventions can increase waterpipe quit rates among waterpipe smokers. We found insufficient evidence to assess whether varenicline or bupropion increased waterpipe abstinence; available evidence is compatible with effect sizes similar to those seen for cigarette smoking cessation.  Given e-health interventions' potential reach and effectiveness for waterpipe cessation, trials with large samples and long follow-up periods are needed. Future studies should use biochemical validation of abstinence to prevent the risk of detection bias. Finally, there has been limited attention given to high-risk groups for waterpipe smoking, such as youth, young adults, pregnant women, and dual or poly tobacco users. These groups would benefit from targeted studies.

Therapeutic potential of flavonoids in cancer: ROS-mediated mechanisms.

Cancer is a leading cause of morbidity and mortality around the globe. Reactive oxygen species (ROS) play contradicting roles in cancer incidence and progression. Antioxidants have attracted attention as emerging therapeutic agents. Among these are flavonoids, which are natural polyphenols with established anticancer and antioxidant capacities. Increasing evidence shows that flavonoids can inhibit carcinogenesis via suppressing ROS levels. Surprisingly, flavonoids can also trigger excessive oxidative stress, but this can also induce death of malignant cells. In this review, we explore the inherent characteristics that contribute to the antioxidant capacity of flavonoids, and we dissect the scenarios in which they play the contrasting role as pro-oxidants. Furthermore, we elaborate on the pathways that link flavonoid-mediated modulation of ROS to the prevention and treatment of cancer. Special attention is given to the ROS-mediated anticancer functions that (-)-epigallocatechin gallate (EGCG), hesperetin, naringenin, quercetin, luteolin, and apigenin evoke in various cancers. We also delve into the structure-function relations that make flavonoids potent antioxidants. This review provides a detailed perspective that can be utilized in future experiments or trials that aim at utilizing flavonoids or verifying their efficacy for developing new pharmacologic agents. We support the argument that flavonoids are attractive candidates for cancer therapy.

The Effect of Different Ester Chain Modifications of Two Guaianolides for Inhibition of Colorectal Cancer Cell Growth.

Several sesquiterpene lactones (STLs) have been tested as lead drugs in cancer clinical trials. Salograviolide-A (Sal-A) and salograviolide-B (Sal-B) are two STLs that have been isolated from Centaurea ainetensis, an indigenous medicinal plant of the Middle Eastern region. The parent compounds Sal-A and Sal-B were modified and successfully prepared into eight novel guaianolide-type STLs (compounds 1-8) bearing ester groups of different geometries. Sal-A, Sal-B, and compounds 1-8 were tested against a human colorectal cancer cell line model with differing p53 status; HCT116 with wild-type p53 and HCT116 p53-/- null for p53, and the normal-like human colon mucosa cells with wild-type p53, NCM460. IC50 values indicated that derivatization of Sal-A and Sal-B resulted in potentiation of HCT116 cell growth inhibition by 97% and 66%, respectively. The effects of the different molecules on cancer cell growth were independent of p53 status. Interestingly, the derivatization of Sal-A and Sal-B molecules enhanced their anti-growth properties versus 5-Fluorouracil (5-FU), which is the drug of choice in colorectal cancer. Structure-activity analysis revealed that the enhanced molecule potencies were mainly attributed to the position and number of the hydroxy groups, the lipophilicity, and the superiority of ester groups over hydroxy substituents in terms of their branching and chain lengths. The favorable cytotoxicity and selectivity of the potent molecules, to cancer cells versus their normal counterparts, pointed them out as promising leads for anti-cancer drug design.

7-O-methylpunctatin, a Novel Homoisoflavonoid, Inhibits Phenotypic Switch of Human Arteriolar Smooth Muscle Cells.

Remodeling of arterioles is a pivotal event in the manifestation of many inflammation-based cardio-vasculopathologies, such as hypertension. During these remodeling events, vascular smooth muscle cells (VSMCs) switch from a contractile to a synthetic phenotype. The latter is characterized by increased proliferation, migration, and invasion. Compounds with anti-inflammatory actions have been successful in attenuating this phenotypic switch. While the vast majority of studies investigating phenotypic modulation were undertaken in VSMCs isolated from large vessels, little is known about the effect of such compounds on phenotypic switch in VSMCs of microvessels (microVSMCs). We have recently characterized a novel homoisoflavonoid that we called 7-O-methylpunctatin (MP). In this study, we show that MP decreased FBS-induced cell proliferation, migration, invasion, and adhesion. MP also attenuated adhesion of THP-1 monocytes to microVSMCs, abolished FBS-induced expression of MMP-2, MMP-9, and NF-κB, as well as reduced activation of ERK1/2 and FAK. Furthermore, MP-treated VSMCs showed an increase in early (myocardin, SM-22α, SM-α) and mid-term (calponin and caldesmon) differentiation markers and a decrease in osteopontin, a protein highly expressed in synthetic VSMCs. MP also reduced transcription of cyclin D1, CDK4 but increased protein levels of p21 and p27. Taken together, these results corroborate an anti-inflammatory action of MP on human microVSMCs. Therefore, by inhibiting the synthetic phenotype of microVSMCs, MP may be a promising modulator for inflammation-induced arteriolar pathophysiology.

Metal-Organic Framework Photocatalyst Incorporating Bis(4'-(4-carboxyphenyl)-terpyridine)ruthenium(II) for Visible-Light-Driven Carbon Dioxide Reduction.

In this study, we report the successful incorporation of the photoactive bis(4'-(4-carboxyphenyl)-terpyridine)ruthenium(II) (Ru(cptpy)2) strut into a robust metal-organic framework (MOF), AUBM-4. The single crystal X-ray analysis revealed the formation of a new one-dimensional structure of Ru(cptpy)2 complexes linked together by Zr atoms that are eight coordinated with O atoms. The chemically stable MOF structure was employed as an efficient photocatalyst for carbon dioxide conversion to formate under visible light irradiation. To the best of our knowledge, the obtained conversion rate is among the highest reported in the literature for similar systems. Our strategy of using the Ru(cptpy)2 complex as a linker to construct the MOF catalyst appears to be very promising in artificial photosynthesis.

Physicochemical, melissopalynological and antioxidant properties of artisanal honeys from Lebanon.

Sixteen honeydew and 15 floral honeys from Lebanon were analyzed for pollen spectra and physicochemical parameters. A total of 37 families and 67 taxa were recorded with the honeybees producing honeydew honey exhibiting a more diverse foraging behavior than those making floral honeys. The honeydew and floral honeys exhibited differences in moisture content, pH, electrical conductivity, color, protein and Maillard reaction products. The honeydew honeys contained more total phenols, had higher antioxidant contents, and displayed higher antioxidant capacities than the floral samples in the Trolox equivalent antioxidant capacity, oxygen radical absorbance capacity, inhibition of superoxide dismutase activity and protection of red blood cells against hemolysis assays. The honey samples exhibited higher antioxidant capacities, in the aforementioned assays, than their corresponding methanol-extractable phenol fractions although the differences did not reach statistical significance in the floral samples. The relative antioxidant capacity indices which integrate measures of antioxidant capacity from the different assays of the honey samples and their corresponding extracts exhibited similar patterns (r = 0.9774, 0.9937) thereby indicating that the antioxidative behavior of the entire honeys is mirrored by their methanol-extractable phenolic fractions.

High photo-currents with a zwitterionic thiocyanate-free dye in aqueous-based dye sensitized solar cells.

We report a new water soluble and stable thiolate/disulfide redox couple (T(-)/DS) and its use with a new zwitterionic and thiocyanate-free dye (T169) in a 100% aqueous electrolyte system. A DSSC incorporating T169 and the T(-)/DS showed the highest photocurrents (Jsc = 13.30 mA cm(-2)) and IPCE% (84%) values reported to date. In addition, a 2000 h long-term stability measurement was performed, where Jsc and Voc of the above mentioned DSSC stayed somehow the same except for the fill factor (FF) which decreased from 0.62 to 0.48 and consequently lowered the total efficiency (from η = 4.5% on day 1 to η = 3.3% after 2000 h).

Time resolved study of three ruthenium(II) complexes at micellar surfaces: A new long excited state lifetime probe for determining critical micelle concentration of surfactant nano-aggregates.

Three different ruthenium complexes have been synthesized and their luminescence properties in different solvent environments are reported. Luminescence intensities and excited state lifetimes of Ru-I, Ru-II and Ru-III vary with solvent viscosity. The excited state lifetime of Ru-I linearly increases in the viscosity range 1.76-12,100cP. Ru-II shows two linear increases: one in the low and another in the high viscosity ranges, whereas Ru-III illustrates a linear enhancement only in the low viscosity range. Interestingly, luminescence intensities and excited state lifetimes of Ru-I, Ru-II and Ru-III are found to be sensitive to nano-aggregation. However, the surfactant head charge and that of the ruthenium center as well as the hydrophobic tail of the ancillary ligand of the complexes have a great role in deciding the nature of the interaction and on the excited state properties at micellar surfaces. It is proposed that the long lifetime of Ru-III in water could be due to the coiling of the carbon chain of the ancillary ligand around the ruthenium center. At micelle surface, this coiling of the carbon chain is lost due to the parallel alignment with surfactants and thus quenching of the excited state lifetime is seen. Furthermore, it is shown that the variation of the excited state lifetime with respect to the change in surfactant concentration is a result of the formation of micelles from the surfactant monomer, thus, a novel technique for the determination of the critical micelle concentration (cmc) based on the long excited state lifetime of Ru-III located at the micellar nano-aggregates is reported.

Anti-Inflammatory and Cytostatic Activities of a Parthenolide-Like Sesquiterpene Lactone from Cota palaestina subsp. syriaca.

A sesquiterpene lactone 1-ß,10-Epoxy-6-hydroxy-1,10H-inunolide (K100) was isolated through "bioassay-guided fractionation" from Cota palaestina subsp. syriaca, an Eastern Mediterranean endemic plant. K100 inhibited endotoxin- (ET-) induced proinflammatory markers: IL-6, MMP-9, and NO in normal mouse mammary SCp2 Cells. Molecular docking in silico suggested that K100, having highly analogous structure as parthenolide (PTL), an anticancer compound, could bind PTL target proteins at similar positions and with comparable binding affinities. Both compounds, K100 and PTL, inhibited the proliferation and prolonged the S-phase of the cell cycle of breast adenocarcinoma MDA-MB-231 cells grown in 2D cultures. Noncytotoxic concentrations of K100 and PTL decreased the proliferation rate of MDA-MB-231 and shifted their morphology from stellate to spherical colonies in 3D cultures. This was accompanied with a significant increase in the amount of small colonies and a decrease in the amount of large colonies. Moreover, K100 and PTL decreased cellular motility and invasiveness of MDA-MB-231 cells. In summary, these results suggest that K100 exhibits PTL-analogous anti-inflammatory, cytostatic, and antimetastatic effects.

Universal low-temperature MWCNT-COOH-based counter electrode and a new thiolate/disulfide electrolyte system for dye-sensitized solar cells.

A new thiolate/disulfide organic-based electrolyte system composed of the tetrabutylammonium salt of 2-methyl-5-trifluoromethyl-2H-[1,2,4]triazole-3-thiol (S(-)) and its oxidized form 3,3'-dithiobis(2-methyl-5-trifluoromethyl-2H-[1,2,4]triazole) (DS) has been formulated and used in dye-sensitized solar cells (DSSCs). The electrocatalytic activity of different counter electrodes (CEs) has been evaluated by means of measuring J-V curves, cyclic voltammetry, Tafel plots, and electrochemical impedance spectroscopy. A stable and low-temperature CE based on acid-functionalized multiwalled carbon nanotubes (MWCNT-COOH) was investigated with our S(-)/DS, I(-)/I3(-), T(-)/T2, and Co(II/III)-based electrolyte systems. The proposed CE showed superb electrocatalytic activity toward the regeneration of the different electrolytes. In addition, good stability of solar cell devices based on the reported electrolyte and CE was shown.

Differential growth inhibitory effects of highly oxygenated guaianolides isolated from the Middle Eastern indigenous plant Achillea falcata in HCT-116 colorectal cancer cells.

Medicinal plants play a crucial role in traditional medicine and in the maintenance of human health worldwide. Sesquiterpene lactones represent an interesting group of plant-derived compounds that are currently being tested as lead drugs in cancer clinical trials. Achillea falcata is a medicinal plant indigenous to the Middle Eastern region and belongs to the Asteraceae family, which is known to be rich in sesquiterpene lactones. We subjected Achillea falcata extracts to bioassay-guided fractionation against the growth of HCT-116 colorectal cancer cells and identified four secotanapartholides, namely 3-ß-methoxy-isosecotanapartholide (1), isosecotanapartholide (2), tanaphallin (3), and 8-hydroxy-3-methoxyisosecotanapartholide (4). Three highly oxygenated guaianolides were isolated for the first time from Achillea falcata, namely rupin A (5), chrysartemin B (6), and 1ß, 2ß-epoxy-3ß,4α,10α-trihydroxyguaian-6α,12-olide (7). These sesquiterpene lactones showed no or minor cytotoxicity while exhibiting promising anticancer effects against HCT-116 cells. Further structure-activity relationship studies related the bioactivity of the tested compounds to their skeleton, their lipophilicity, and to the type of functional groups neighboring the main alkylating center of the molecule.

Photophysical properties of new cyclometalated ruthenium complexes and their use in dye sensitized solar cells.

A new class of cyclometalated ruthenium complexes, Ru(C^N^N')(N^N'^N'')·Cl where N^N'^N'' = 4,4',4''-tricarboxy-2,2':6',2''-terpyridine and C^N^N' = substituted 6-phenyl-2,2'-bipyridine, for Dye Sensitized Solar Cells (DSSCs) is proposed. We have investigated the effect of different substituents (R = COOH, thiophen-2-yl, F and OCH(3)) on the ancillary C^N^N' ligand on the photophysical properties and performance of the six different cyclometalated ruthenium complexes in DSSCs. Using an ionic liquid based electrolyte, efficiencies up to η = 3.06% have been attained under 1 sun irradiation. Moreover, the T66 based DSSC exhibited a good stability under 1000 W m(2) light soaking at 60 °C for 24 days, retaining 92.8% of its initial efficiency.

Enhancement of photocurrent in dye sensitized solar cells incorporating a cyclometalated ruthenium complex with cuprous iodide as an electrolyte additive.

A new cyclometalated ruthenium complex, [Ru(6'-phenyl-4'-thiophen-2-yl-[2,2']bipyridinyl-4-carboxylic acid)(4,4',4''-tricarboxy- 2,2':6',2''-terpyridine)]Cl, for Dye Sensitized Solar Cells (DSSCs) is proposed. We have investigated the use of cuprous iodide (CuI) as an electrolyte additive, which in turn has shown photocurrent enhancements of more than 25% in our dye based cells. Using an ionic liquid based electrolyte, an efficiency of η = 5.7% has been accomplished under 1 sun irradiation. The origin of this photocurrent enhancement upon the CuI addition was studied by means of impedance spectroscopy and cyclic voltammetry under dark conditions. The reason behind such a photocurrent enhancement is attributed to an electrocatalytic effect of the CuI on the regeneration of the oxidized dye. Furthermore, the CuI addition did not affect the recombination processes between the injected electrons and the electrolyte nor the electron lifetime in the semiconductor TiO(2) film, which in turn resulted in no changes in the photovoltage.

Pulse-front propagation and interaction during the growth of CdS nanoparticles in a gel.

We studied the spatiotemporal dynamics of a new system consisting of sulfide ions (outer electrolyte) diffusing into an organic gel (gelatin) containing mercaptoethanol-capped cadmium ions (inner electrolyte). The product, cadmium sulfide, exhibits a faint yellow transparent propagating front starting at the gel-outer electrolyte interface. When subjected to UV light, this system reveals fluorescing CdS nuclei localized spatially in a narrow region, called pulse, that leads the front and propagates down the tube. We show that the pulse consists of CdS nanoclusters of an average size of about 4 nm, whereas the trailing front consists of 6-8 nm cubic-phase CdS crystallites. The width of the pulse remains constant in time, t, at about 2 mm and independent of the outer concentration S0. It was found that the speed of the pulse fluctuates as the concentration of the capping agent is varied, with fastest pulses attained at a concentration of 40 mM for two different outer concentrations of sulfide ions. The origin of the yellow fluorescence of the pulse originates from emission from surface states. This dynamical system was then theoretically studied using a competitive particle growth model. The resulting evolution equations were solved numerically, and the results were compared to the experimental findings. It was shown that the model agrees in many aspects with the experiment. The densities of small particles and large particles rho were shown to evolve like a pulse and a front, respectively. The front was shown to extend "diffusively" as t1/2, as found experimentally. The distance traveled by the pulse xpeak was shown to increase with outer concentration S0 and obeys a concentration power law xpeak approximately S(0)1/4. The width w of the pulse also obeys a time power law w approximately ta with a crossover between early times (a=1/3) and intermediate times (a=0). This system would enable us to study the early time dynamics of Liesegang systems.

Re-evaluation of recombination losses in dye-sensitized cells: the failure of dynamic relaxation methods to correctly predict diffusion length in nanoporous photoelectrodes.

Photocurrents generated by thick, strongly absorbing, dye-sensitized cells were reduced when the electrolyte iodine concentration was increased. Electron diffusion lengths measured using common transient techniques (L(n)) were at least two times higher than diffusion lengths measured at steady state (L(IPCE)). Charge collection efficiency calculated using L(n) seriously overpredicted photocurrent, while L(IPCE) correctly predicted photocurrent. This has implications for optimizing cell design.

Structure/function relationships in dyes for solar energy conversion: a two-atom change in dye structure and the mechanism for its effect on cell voltage.

Recombination between injected electrons and iodine limits the photovoltage in dye-sensitized solar cells (DSSCs). We have recently suggested that many new dye molecules, intended to improve DSSCs, can accelerate this reaction, negating the expected improvement (J. Am. Chem. Soc. 2008, 130, 2907). Here we study two dyes with only a two-atom change in the structure, yet which give different V(oc)s. Using a range of measurements we show conclusively that the change in V(oc) is due solely to the increase in the recombination rate. From the structure of the dyes, and literature values for iodine binding of similar compounds, we find that it is very likely that the change in V(oc) is due solely to the difference in iodine binding at the site of the two-atom change. Using the large amount of literature on iodine complexation, we suggest structures for dyes that might show improved V(oc).

Application of synchronous fluorescence scan spectroscopy for size dependent simultaneous analysis of CdTe nanocrystals and their mixtures.

In this paper, synchronous fluorescence scan (SFS) spectroscopy has been applied for the first time for the simultaneous determination of a mixture of CdTe fluorescent nanocrystals (NCs) of various sizes without a pre-separation step. It is observed that synchronous fluorescence maximum correlates well with the size of the nanocrystals, i.e.; the lambda(SFS)(max) is useful to determine size dependency of NCs. Synchronous fluorescence maximum along with the second derivative can identify individual NCs in a mixture in water. The method is found to be simple, sensitive, selective and fast for NCs determination in aqueous media.