Large optical depth frequency modulation spectroscopy.

Band-resolved frequency modulation spectroscopy is a common method to measure weak signals of radiative ensembles. When the optical depth of the medium is large, the signal drops exponentially and the technique becomes ineffective. In this situation, we show that a signal can be recovered when a larger modulation index is applied. Noticeably, this signal can be dominated by the natural linewidth of the resonance, regardless of the presence of inhomogeneous line broadening. We implement this technique on a cesium vapor, and then explore its main spectroscopic features. This work opens the road towards measurement of cooperative emission effects in bulk atomic ensemble.

Cooperative Emission of a Pulse Train in an Optically Thick Scattering Medium.

An optically thick cold atomic cloud emits a coherent flash of light in the forward direction when the phase of an incident probe field is abruptly changed. Because of cooperativity, the duration of this phenomena can be much shorter than the excited lifetime of a single atom. Repeating periodically the abrupt phase jump, we generate a train of pulses with short repetition time, high intensity contrast, and high efficiency. In this regime, the emission is fully governed by cooperativity even if the cloud is dilute.

Cooperative Emission of a Coherent Superflash of Light.

We investigate the transient coherent transmission of light through an optically thick cold strontium gas. We observe a coherent superflash just after an abrupt probe extinction, with peak intensity more than three times the incident one. We show that this coherent superflash is a direct signature of the cooperative forward emission of the atoms. By engineering fast transient phenomena on the incident field, we give a clear and simple picture of the physical mechanisms at play.

Chemical looping combustion of biomass-derived syngas using ceria-supported oxygen carriers.

Cu, Ni and Fe oxides supported on ceria were investigated for their performance as oxygen carriers during the chemical looping combustion of biomass-derived syngas. A complex gas mixture containing CO, H2, CO2, CH4 and other hydrocarbons was used to simulate the complex fuel gas environment derived from biomass gasification. Results show that the transfer of the stored oxygen into oxidants for the supported Cu and Ni oxides at 800°C for the combustion of syngas was effective (>85%). The unsupported Cu oxide showed high oxygen carrying capacity but particle sintering was observed at 800°C. A reaction temperature of 950°C was required for the supported Fe oxides to transfer the stored oxygen into oxidants effectively. Also, for the complex fuel gas environment, the supported Ni oxide was somewhat effective in reforming CH4 and other light hydrocarbons into CO, which may have benefits for the reduction of tar produced during biomass pyrolysis.

Carotid endarterectomy improves peripheral but not central arterial stiffness.

OBJECTIVE: Carotid endarterectomy (CEA) reduces the risk of cerebrovascular events due to the presence of atherosclerotic plaque in the internal carotid artery. Arterial stiffness is an indicator of cardiovascular risk and strongly associates with the development of atherosclerosis. This study aims to assess the short-term effect of CEA on arterial stiffness and haemodynamics. DESIGN: Prospective observational study. METHODS: Measurements of arterial stiffness and haemodynamics, including carotid-femoral pulse wave velocity (cfPWV), carotid-radial PWV (crPWV), augmentation pressure, augmentation index, subendocardial viability ratio, central pressures and pulse pressure amplification, were performed pre- and 6 weeks post-CEA on both surgical and non-surgical sides. RESULTS: Fifty-nine patients completed the study (n = 46 men, age 68.9 ± 10.1 years). crPWV was decreased after CEA on the surgical (P = 0.01) and non-surgical side (P = 0.0008), AIx75 tended to decrease only on the surgical side (P = 0.06). cfPWV did not change significantly on either side. CONCLUSION: We assessed, for the first time, the short-term effect of CEA on arterial stiffness and haemodynamics. CEA improved peripheral but not central arterial stiffness. This study provides evidence for significant changes in certain arterial stiffness and haemodynamic parameters. Longer-term follow-up will assess whether these changes are sustained and whether CEA is associated with further haemodynamic benefits.

A modified dynamic evolving neural-fuzzy approach to modeling customer satisfaction for affective design.

Affective design is an important aspect of product development to achieve a competitive edge in the marketplace. A neural-fuzzy network approach has been attempted recently to model customer satisfaction for affective design and it has been proved to be an effective one to deal with the fuzziness and non-linearity of the modeling as well as generate explicit customer satisfaction models. However, such an approach to modeling customer satisfaction has two limitations. First, it is not suitable for the modeling problems which involve a large number of inputs. Second, it cannot adapt to new data sets, given that its structure is fixed once it has been developed. In this paper, a modified dynamic evolving neural-fuzzy approach is proposed to address the above mentioned limitations. A case study on the affective design of mobile phones was conducted to illustrate the effectiveness of the proposed methodology. Validation tests were conducted and the test results indicated that: (1) the conventional Adaptive Neuro-Fuzzy Inference System (ANFIS) failed to run due to a large number of inputs; (2) the proposed dynamic neural-fuzzy model outperforms the subtractive clustering-based ANFIS model and fuzzy c-means clustering-based ANFIS model in terms of their modeling accuracy and computational effort.

Synthesis of Co3O4 nanowire arrays supported on Ni foam for removal of volatile organic compounds.

Crystalline Co3O4 nanowire arrays freely supported on Ni foam are successfully synthesized using a template-free method. The effects of reaction time, concentration of reactants, and temperature on the morphology of the nanowires are studied. The results indicate that uniform Co3O4 nanowires could be synthesized at 90 degrees C, and a transformation of the samples' morphology from nanoparticles to nanowires to microrods is observed by controlling the concentration of the reactants. The well-ordered nanowires synthesized under the selected reaction conditions are composed of spinel Co3O4 with diameters of 500-580 nm and lengths of 6-8 microm. These nanowires show good catalytic activity for the ozone catalytic oxidation of toluene.

Fly-ash products from biomass co-combustion for VOC control.

Experiments were conducted in a continuous flow reactor at room temperature to evaluate the elimination of low-concentration toluene in the gas phase to verify if fly-ash products from biomass combustion in an ozonation system could be used in the removal of volatile organic compounds. The fly-ash products from pure biomass combustion (Ash(100)) demonstrated the highest ozonation activities upon the removal of low-concentration toluene (1.5 ppmv), followed by the fly-ash products from co-combustion (Ash(30)) and the coal combustion (Ash(0)). Kinetic experiments showed that the activation energy of the toluene elimination process was substantially reduced with the use of ozone and the reaction intermediates, such as formic acids, aldehydes, etc. Results also showed that the intermediates were reduced with increasing humidity level. The combined use of fly-ash products and zeolite 13X enhanced the removal of toluene to above 90% and suppressed the release of residual ozone and intermediates by holding them in the adsorbed phase.

Catalytic ozonation of toluene using zeolite and MCM-41 materials.

The effects of passing ozone over different zeolite and MCM-41 materials to remove toluene were investigated. Different ozone-to-toluene ratios were used to evaluate the catalytic performance during ozonation. The micro- and meso-porous materials removed about 50% of the toluene via adsorption and another 20-40% was decomposed by ozonation, which was catalytically enhanced by the zeolite and MCM-41 materials. The catalytic reaction portion increased by using a higher ozone inlet concentration and it was further enhanced to around 50% with the use of more adsorbents or with longer residence times. Inside the porous structure of the material, ozone was either decomposed into active atomic oxygen for reactions or converted into oxygen for active site regeneration. The number of Lewis acid sites in the adsorbents for ozone decomposition and byproduct generation during the reactions limit the catalytic activities. Trace amounts of intermediates including aldehydes and organic acids were quantified in the ozonation process. A higher ozone inlet concentration helped to reduce intermediate species formation but it led to more residual ozone in the exhaust. The high adsorption capability of the zeolite and MCM-41 adsorbents could serve as reservoirs for suppressing the release of intermediate species to the exhaust.

Programs to facilitate tuberculosis drug discovery: the tuberculosis antimicrobial acquisition and coordinating facility.

There is a real need to discover new drugs that are active on drug-resistant tuberculosis (TB), and for drugs that will shorten the time of therapy. Large pharmaceutical companies have traditionally led the quest for discovering and developing new antiinfective agents but this is not the case when it comes to diseases like tuberculosis that primarily occur in resource restricted countries. Throughout the world many research groups are actively engaged in the scientific discovery of new TB drugs. Unfortunately, most research laboratories do not have the necessary safety facilities or resources for all facets of TB drug discovery. The Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF) was established in order to make comprehensive testing services available at no cost to research laboratories with an interest in discovering new TB drugs. The TAACF is a consortium of contracts managed and funded by the National Institute of Allergy and Infectious Diseases (National Institutes of Health, Bethesda, MD) as a resource to support preclinical drug discovery and development. The core of the TAACF is the Southern Research Institute, Birmingham, AL, which supports compound acquisition, storage, medicinal chemistry, and high throughput assays. Other collaborating groups provide biological data on antimycobacterial activity and cytotoxicity, preliminary in vivo toxicity, oral bioavailability and efficacy in animal models, specialty testing (such as activity against non-replicating persistent bacteria), and assistance in technology transfer for developing comprehensive promotional packages and facilitating partnerships with pharmaceutical companies for drug development. The TAACF program and recent progress that has been publicly disclosed by suppliers is reviewed. There are many aspects promising of the program that will not be discussed due to confidentially.

Potential use of a combined ozone and zeolite system for gaseous toluene elimination.

This study investigated the performance of a combined ozone and zeolite system in eliminating gaseous toluene which is a major contaminant in many industrial and indoor environments. The hypothesis that the removal of toluene by ozone can be substantially affected by confining the oxidation reaction in a zeolite structure was evaluated. The degradation of toluene seemed to be contributed by the active oxygen atom generated from the decomposition of ozone at the Lewis acid sites in the zeolite 13X. Air containing toluene levels at 1.5, 2 and 3 ppm was injected with ozone in the range of 0-6 ppm before being vented into a fixed amount of 3600 g zeolite 13X with 90 mm bed-length. The experimental results showed that the elimination rate of toluene was significantly enhanced when compared to using zeolite or ozone alone. In particular, over 90% of the 1.5 ppm toluene was removed when 6 ppm ozone was used at 40% relative humidity level. Deactivation of the zeolite 13X after a few hours of reactions under the current experimental conditions was probably due to the adsorbed water, carbon dioxide and the reaction by-products. The residue species left in the zeolite and the intermediate species in the exhaust gas stream were characterized by FT-IR, GC-MS and HP-LC methods, respectively. A distinctive peak of O atom attached to the Lewis acid site at 1380 cm(-1) was found in the FT-IR spectrum and trace amount of aldehydes was found to be the reaction by-products.

Removal of batteries from solid waste using trommel separation.

This paper describes the design and testing of a trommel for separation of batteries from solid waste. A trommel is a cylindrical separation device that rotates and performs size separation. It has also been used in areas such as municipal solid waste (MSW) processing, classifying construction and demolition debris, screening mass-burn incinerator ash and compost processing. A trommel has been designed based on size separation to separate household batteries from solid waste, which can then be used as feedstock for alternative applications of solid waste combustion, particularly where the metal content of the product is also a critical parameter, such as the Co-Co process for integrated cement and power production. This trommel has been tested with batches of university office and restaurant wastes against various factors. The recovery efficiency of batteries increases with decreasing inclination angle of the trommel and decreasing rotational speed. A physical characterization of the university solid waste has been performed with a 20-kg sample of the tested waste. It was found that there is a trend of decreasing recovery of batteries with increasing paper composition, and a trend of increasing recovery of batteries with increasing organic materials composition.

Intracoronary delivery of adenovirus encoding adenylyl cyclase VI increases left ventricular function and cAMP-generating capacity.

BACKGROUND: We tested the hypothesis that intracoronary injection of a recombinant adenovirus encoding adenylyl cyclase type VI (AC(VI)) would increase cardiac function in pigs. METHODS AND RESULTS: Left ventricular (LV) dP/dt and cardiac output in response to isoproterenol and NKH477 stimulation were assessed in normal pigs before and 12 days after intracoronary delivery of histamine followed by intracoronary delivery of an adenovirus encoding lacZ (control) or AC(VI) (1.4x10(12) vp). Animals that had received AC(VI) gene transfer showed increases in peak LV dP/dt (average increase of 1267+/-807 mm Hg/s; P=0.0002) and cardiac output (average increase of 39+/-20 mL. kg(-1). min(-1); P<0.0001); control animals showed no changes. Increased LV dP/dt was evident 6 days after gene transfer and persisted for at least 57 days. Basal heart rate, blood pressure, and LV dP/dt were unchanged, despite changes in cardiac responsiveness to catecholamine stimulation. Twenty-three hour ECG recordings showed no change in mean heart rate or ectopic beats and no arrhythmias. LV homogenates from animals receiving AC(VI) gene transfer showed increased AC(VI) protein content (P=0.0007) and stimulated cAMP production (P=0.0006), confirming transgene expression and function; basal LV AC activity was unchanged. Increased cAMP-generating capacity persisted for at least 18 weeks (P<0.0002). CONCLUSIONS: Intracoronary injection of a recombinant adenovirus encoding AC provides enduring increases in cardiac function.

Chronic treatment with phentermine combined with fenfluramine lowers plasma serotonin.

As expected on the basis of published research in both humans and animals, treatment with phentermine/fenfluramine lowers plasma 5-hydroxytryptamine [corrected], whereas treatment with phentermine had no significant effect. In light of these findings, future research should focus on mechanisms other than increased plasma 5-hydroxytryptamine [corrected] to explain how fenfluramine increases the risk of primary pulmonary hypertension and valvular heart disease.

Pharmacologic induction of weight loss to treat type 2 diabetes.

OBJECTIVE: Most individuals with type 2 diabetes are overweight, and weight loss for them is an important therapeutic objective. However, usual weight-loss strategies have generally not produced sustained weight loss. Pharmacologic agents to assist weight loss might be useful, but no long-term data on their effectiveness and safety in patients with type 2 diabetes are available. We therefore initiated a 2-year placebo-controlled trial of the weight-loss medications fenfluramine and phentermine in type 2 diabetic subjects. RESEARCH DESIGN AND METHODS: A total of 44 overweight (> 120% ideal body weight) subjects with type 2 diabetes were enrolled in a randomized, placebo-controlled, double-blind trial of fenfluramine and phentermine. All subjects received intensive nutrition counseling, an exercise prescription, and instruction in behavior modification. Subjects were randomly assigned to 20 mg fenfluramine three times a day and 37.5 mg phentermine daily (n = 23) or dual placebos (n = 21). Diabetes medications were adjusted as necessary to achieve glycemic goals. Changes in weight, glycemia, lipemia, and blood pressure were assessed every 2 months, as were adverse events. In September 1997, when fenfluramine was withdrawn from the U.S. market, fenfluramine was stopped in all subjects. Thus the length of drug treatment varied, but 16 subjects (8 in each group) reached 12 months of treatment. Only data obtained before the withdrawal of fenfluramine are included in this report. RESULTS: A study termination, diabetes medications had been reduced in 1 subject in the placebo group (5%) and 11 subjects in the drug treatment group (52%) (P = 0.005). Drug treatment resulted in significant reductions in body weight, BMI, and HbA1c at all time points through 6 months. Changes in weight at 6 months were -2.7 +/- 1.4 kg (mean +/- SEM) with placebo treatment and -9.6 +/- 1.5 kg with drug treatment (P = 0.003). Even though more subjects in the drug treatment group required reductions in diabetes medications, at 6 months, changes in HbA1c were -0.3 +/- 0.2% with placebo treatment and -1.6 +/- 0.3% with drug treatment (P = 0.002). Fasting plasma glucose and triglycerides were significantly reduced at some time points with drug treatment. No serious adverse events attributable to study medications were observed. CONCLUSIONS: Premature study termination decreased the power of our study at later time points. However, our data suggest that weight loss medications are an effective treatment for type 2 diabetes during active weight loss. Whether the benefit persists after weight loss has stopped remains to be determined.

Inhibitors of mammalian melanocyte tyrosinase: in vitro comparisons of alkyl esters of gentisic acid with other putative inhibitors.

To discover safe and effective topical skin-lightening agents, we have evaluated alkyl esters of the natural product gentisic acid (GA), which is related to our lead compound methyl gentisate (MG), and four putative tyrosinase inhibitors, utilizing mammalian melanocyte cell cultures and cell-free extracts. Desirable characteristics include the ability to inhibit melanogenesis in cells (IC50 < 100 microg/mL) without cytotoxicity, preferably due to tyrosinase inhibition. Of the six esters synthesized, the smaller esters (e.g. methyl and ethyl) were more effective enzyme inhibitors (IC50 approximately 11 and 20 microg/mL, respectively). For comparison, hydroquinone (HQ), a commercial skin "bleaching" agent, was a less effective enzyme inhibitor (IC50 approximately 72 microg/mL), and was highly cytotoxic to melanocytes in vitro at concentrations substantially lower than the IC50 for enzymatic inhibition. Kojic acid was a potent inhibitor of the mammalian enzyme (IC50 approximately 6 microg/mL), but did not reduce pigmentation in cells. Both arbutin and magnesium ascorbyl phosphate were ineffective in the cell-free and cell-based assays. MG at 100 microg/mL exhibited a minimal inhibitory effect on DHICA oxidase (TRP 1) and no effect on DOPAchrome tautomerase (TRP-2), suggesting that MG inhibits melanogenesis primarily via tyrosinase inhibition. MG and GA were non-mutagenic at the hprt locus in V79 Chinese hamster cells, whereas HQ was highly mutagenic and cytotoxic. The properties of MG in vitro, including (1) pigmentation inhibition in melanocytes, (2) tyrosinase inhibition and selectivity, (3) reduced cytotoxicity relative to HQ, and (4) lack of mutagenic potential in mammalian cells, establish MG as a superior candidate skin-lightening agent.

Screening of compounds for antimicrosporidial activity in vitro.

Relatively few effective compounds are available for treating microsporidiosis in humans. In this study, several compounds were assayed for activity against Encephalitozoon intestinalis (Cali, Kotler et Orenstein, 1993) and Vittaforma corneae Shadduck, Meccoli, Davis et Font, 1990 in vitro. Of the benzimidazoles tested, albendazole was most effective and the MIC50 values were 8.0 ng/ml and 55.0 ng/ml for E. intestinalis and V. corneae, respectively. Fumagillin and its analogue, TNP-470 were nearly equally effective against both E. intestinalis and V. corneae. The MIC50 values of fumagillin were 0.52 ng/ml and 0.81 ng/ml, and the MIC50 values of TNP-470 were 0.35 ng/ml and 0.38 ng/ml for E. intestinalis and V. corneae, respectively. In addition, 12 of 44 purines and pteridines with putative tubulin binding activity that were synthesized at Southern Research Institute (SRI), inhibited microsporidial replication by more than 50% at concentrations that were not toxic to the host cells. Several chitin synthesis/assembly inhibitors inhibited growth of the microsporidia in vitro but were toxic for the host cells making it difficult to interpret the results. One exception was lufenuron, which caused no significant toxicity to the host cells and expressed approximate MIC50 values of 2.95 micrograms/ml and 6.3 micrograms/ml against E. intestinalis and V. corneae, respectively. These results warrant further studies on albendazole, fumagillin, TNP-470, lufenuron, and the selected SRI purines and pteridines for developing therapeutic strategies for microsporidiosis.

Synthesis and antiviral evaluation of analogs of adenosine-N1-oxide and 1-(Benzyloxy)adenosine.

The activity of a series of compounds related to adenosine-N1-oxide (1) and 1-(benzyloxy)adenosine (42) against vaccinia virus has been determined both in vitro and in a vaccinia mouse tailpox model. Significant activities have been found both in vitro and in vivo for a number of the synthetic compounds.