Evaluating capacity at three government referral hospital emergency units in the kingdom of Eswatini using the WHO Hospital Emergency Unit Assessment Tool.

BACKGROUND: The Kingdom of Eswatini, a lower-middle income nation of 1.45 million in southern Africa, has recently identified emergency care as a key strategy to respond to the national disease burden. We aimed to evaluate the current capacity of hospital emergency care areas using the WHO Hospital Emergency Unit Assessment Tool (HEAT) at government referral hospitals in Eswatini. METHODS: We conducted a cross-sectional study of three government referral hospital emergency care areas using HEAT in May 2018. This standardised tool assists healthcare facilities to assess the emergency care delivery capacity in facilities and support in identifying gaps and targeting interventions to strengthen care delivery within emergency care areas. Senior-level emergency care area employees, including senior medical officers and nurse matrons, were interviewed using the HEAT. RESULTS: All sites provided some level of emergency care 24 h a day, 7 days a week, though most had multiple entry points for emergency care. Only one facility had a dedicated area for receiving emergencies and a dedicated resuscitation area; two had triage areas. Facilities had limited capacity to perform signal functions (life-saving procedures that require both skills and resources). Commonly reported barriers included training deficits and lack of access to supplies, medications, and equipment. Sites also lacked formal clinical management and process protocols (such as triage and clinical protocols). CONCLUSIONS: The HEAT highlighted strengths and weaknesses of emergency care delivery within hospitals in Eswatini and identified specific causes of these system and service gaps. In order to improve emergency care outcomes, multiple interventions are needed, including training opportunities, improvement in supply chains, and implementation of clinical and process protocols for emergency care areas. We hope that these findings will allow hospital administrators and planners to develop effective change management plans.

Exposure to solar ultraviolet radiation limits diet-induced weight gain, increases liver triglycerides and prevents the early signs of cardiovascular disease in mice.

BACKGROUND AND AIMS: Sunlight exposure is associated with a number of health benefits including protecting us from autoimmunity, cardiovascular disease, obesity and diabetes. Animal studies have confirmed that ultraviolet (UV)-B radiation, independently of vitamin D, can limit diet-induced obesity, metabolic syndrome and atherosclerosis. The aim of this study is to investigate whether exposure to the UV radiation contained in sunlight impacts on these disease parameters. METHODS AND RESULTS: We have trialled an intervention with solar UV in obese and atherosclerosis-prone mice. We have discovered that solar-simulated UV can significantly limit diet-induced obesity and reduce atheroma development in mice fed a diet high in sugar and fat. The optimal regime for this benefit was exposure once a week to solar UV equivalent to approximately 30 min of summer sun. Exposure to this optimal dose of solar UV also led to a significant increase in liver triglycerides which may protect the liver from damage. CONCLUSION: Our results show that the UV contained in sunlight has the potential to prevent and treat chronic disease at sites distant from irradiated skin. A major health challenge going forward will be to harness the power of the sun safely, without risking an increase in skin cancers.

Adeno-associated viral serotypes differentially transduce inhibitory neurons within the rat amygdala.

Recombinant adeno-associated viruses (AAV) are frequently used to make localized genetic manipulations within the rodent brain. It is accepted that the different viral serotypes possess differing affinities for particular cell types, but it is not clear how these properties affect their ability to transduce specific neuronal cell sub-types. Here, we examined ten AAV serotypes for their ability to transduce neurons within the rat basal and lateral nuclei of the amygdala (BLA) and the central nucleus of the amygdala (CeA). AAV2 based viral genomes designed to express either green fluorescent protein (GFP) from a glutamate decarboxylase (GAD65) promoter or the far-red fluorescent protein (E2-Crimson) from a phosphate-activated glutaminase (PAG) promoter were created and pseudotyped as AAV2/1, AAV2/4, AAV2/5, AAV2/6, AAV2/7, AAV 2/8, AAV2/9, AAV2/rh10, AAV2/DJ and AAV2/DJ8. These viruses were infused into the BLA and CeA at equal titers and twenty-one days later tissue within the amygdala was examined for viral transduction efficiency. These serotypes transduced neurons with similar efficiency, except for AAV4 and AAV5, which exhibited significantly less efficient neuronal transduction. Notably, AAV4 and AAV5 possess the most divergent capsid protein sequences compared to the other commonly available serotypes. We found that the Gad65-GFP virus did not exclusively express GFP within inhibitory neurons, as assessed by fluorescent in situ hybridization (FISH), but when this virus was used to transduce CeA neurons, the majority of the neurons that expressed GFP were in fact inhibitory neurons and this was likely due to the fact that this nucleus contains a very high percentage of inhibitory neurons.

Assessment of an action against environmental noise: Acoustic durability of a pavement surface with crumb rubber.

Environmental noise is a worldwide problem that has an adverse effect in the quality of life of urban population. Some work has shown that there is a correlation between environmental noise and health issues as sleep disturbance or annoyance. This study presents the time evolution of a test track fabricated with an asphalt mixture with 20% of crumb rubber by weight of bitumen, added by the wet process. A complete surface characterization has been performed by determining tire/pavement sound levels, road texture profiles, in-situ dynamic stiffness and sound absorption of compacted and extracted sample cores. Two measurement campaigns were performed: just after mixture laying and after 3 years in service. This study confirms that the use of crumb rubber as a modifier of bituminous binders (CRMB) can improve the pavement characteristics: gap-graded mixtures with crumb rubber can be used in the action plans as urban rehabilitation measure to fight noise pollution. However, this noise reduction seems to decrease with age at a rate of approximately 0.15 dB(A) per year.

Surface plasmon resonance-based immunoassay for human C-reactive protein.

A rapid and highly-sensitive surface plasmon resonance (SPR)-based immunoassay (IA) has been developed and validated for detecting human C-reactive protein (CRP), a specific biomarker for inflammatory and metabolic disorders, and infections. The 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC)-activated protein A/G (Pr A/G) was diluted in 1% (v/v) 3-aminopropyltriethoxysilane (APTES), dispensed on a KOH-treated gold (Au)-coated SPR chip, and incubated for 30 min. The Pr A/G functionalized Au SPR chip was then bound to anti-human CRP capture antibody (Ab), blocked with bovine serum albumin, and subsequently used for the detection of CRP. The highly-simplified oriented Ab immobilization strategy enabled the leach-proof binding of capture Ab in 5-fold shorter time than conventional procedures. The developed IA detected 1.2-80 ng mL(-1) of CRP with a limit of detection (LOD) and a limit of quantification (LOQ) of 1.2 ng mL(-1) and 4.6 ng mL(-1), respectively. It detected CRP spiked in diluted human whole blood, serum and plasma as well as the CRP levels in the ethylenediaminetetraacetic acid (EDTA) plasma samples of patients with the same precision as the clinically-accredited analyzer-based IA and conventional CRP sandwich ELISA. The Ab-bound SPR chips stored at 4 °C retained their functional activity for 10 weeks, resulting in significant reduction in the overall analysis time.

Determination of furfurals in Manuka honey using piston-cylinder liquid-liquid extraction and gas chromatography.

A rapid analytical approach for the direct measurement of furfurals such as 2-furfural and 5-methyl-2-furfural at parts-per-billion level in Manuka honey is described. The approach employs a piston-cylinder based liquid-liquid extraction device using chloroform extraction solvent. This device substantially reduces extraction time by a factor of 120 times compared to solid phase micro-extraction and reduces solvent consumption by a factor of 25 times compared to liquid-liquid extraction with mechanical agitation. A recently commercialised capillary column offering a high degree of inertness permits separation and detection of the analytes at ultra-trace level without derivatisation. A three-port planar microfluidic device with a mid-point pressure is also incorporated to back-flush heavier compounds in the matrix to improve column longevity and overall system cleanliness. With this approach, analysis is conducted in less than 7min. Repeatability of retention times for all compounds is less than 0.1% (n=20). The compounds cited can be analysed over a range from 1ng/g to 10µg/g in honey with a 5ng/g limit of quantification (LOQ) and correlation coefficients of at least 0.999. Relative precision is less than 2.8% RSD (n=20) at 50ng/g level with analyte extraction efficiency of greater than 99% (n=3) over a range from 5ng/g to 10µg/g in the matrix described. The analytical system requires only minimal maintenance and is suitable for remote site deployment. Under the analytical conditions established and with a practical LOQ of 5ng/g, 100 samples can be analysed before septum/liner/o-ring replacements are needed. As a preventive measure, the pre-column can be replaced once every six months to maintain chromatographic fidelity.

Surface plasmon resonance-based immunoassay for human fetuin A.

This article describes a highly-sensitive surface plasmon resonance (SPR)-based immunoassay (IA) for human fetuin A (HFA), a specific biomarker for atherosclerosis and hepatocellular carcinoma. The assay is based on a novel immobilization procedure that simply involves the dilution of an anti-HFA capture antibody (Ab) in 1% (v/v) 3-aminopropyltriethoxysilane (APTES), followed by its dispensing on a KOH-treated gold (Au)-coated SPR chip and incubation for 30 min. The developed SPR IA detected 0.3-20 ng mL(-1) of HFA with a limit of detection and sensitivity of 0.7 ng mL(-1) and 1 ng mL(-1), respectively. The highly-simplified Ab immobilization procedure is also 5-fold more rapid than conventional procedures. It leads to the leach-proof binding of the capture Ab, which means that the developed SPR IA is highly cost-effective, as the Ab-bound SPR chip could be reused for many repeated HFA IAs after regeneration with 10 mM glycine-HCl, pH 2.0. The Ab-bound SPR chip, stored at 4 °C, lost only 18% of its original activity after 4 months. For the detection of HFA spiked in diluted human whole blood and plasma, the results obtained by the developed SPR IA agreed well with the commercial HFA sandwich ELISA.

Determination of trace ethylene glycol in industrial solvents and lubricants using phenyl boronic acid derivatization and multidimensional gas chromatography.

A practical gas chromatographic approach is introduced for the characterization of trace ethylene glycol in industrial solvents and lubricants. The analytical approach employs single step derivatization technique that effectively converts ethylene glycol to the cyclic boronate ester (2-phenyl-1,3,2-dioxaborolane), using phenyl boronic acid as a derivatizing reagent. The separation of the derivatized product was achieved by using multidimensional gas chromatography. Heavy lubricant matrices like engine crankcase oil were back-flushed to improve sample throughput and system cleanliness. Detection and quantitation of 2-phenyl-1,3,2-dioxaborolane was conducted with mass spectrometry in selected ion monitoring mode. Complete analysis is conducted in less than 10 min. Reproducibility of retention time was found to be less than 0.05% (n=20). Quantitative performance is highly satisfactory, viz. 0.49±0.02 mg kg(-1) (n=12) and 25.5±0.48 mg kg(-1) (n=12) for 0.5 mg kg(-1) and 25 mg kg(-1) spiked concentrations respectively. Over a range from 100 µg kg(-1) to 100 mg kg(-1), the response for 2-phenyl-1,3,2-dioxaborolane is linear with correlation coefficient of 0.998, a practical detection limit of 50 µg kg(-1), and average spiked recoveries for the analyte in the matrices tested range from 93 to 99%. Propylene glycol can also be analyzed using the same approach and water does not inhibit the formation of the derivatives, most probably owing to the use of 2,2-dimethoxypropane as a solvent for the derivatizing agent.

Characterization of phenol and alkyl phenols in organic matrixes with monoethylene glycol extraction and multidimensional gas chromatography/mass spectrometry.

The use of monoethylene glycol as an extraction medium for removing phenol and alkyl phenols in organic matrixes such as hydrocarbons is introduced and combined with a practical analytical multidimensional gas chromatography approach. The analytical approach has been successfully developed for the characterization of phenol, cresols, xylenols, and alkyl phenols like 4-ethylphenol and 2,3,5-trimethylphenol. The technique employs a single-step extraction of the analytes with monoethylene glycol and sonication, followed by multidimensional gas chromatography with mass spectrometry in selected ion monitoring mode for the detection and quantitation. Extraction efficiency of phenol approached 100% while cresols, xylenols, and 4-ethylphenol were 97% or higher and 2,3,5-trimethylphenol was better than 91% under the analytical conditions used. With the technique described, a complete analysis can be conducted in less than 16 min. Reproducibility of area counts at two levels, namely, 5 ppm(w) and 50 ppm(w) over a period of 2 days were found to be less than 4% (n = 20). The analytes of interest was found to be linear over a range from 100 ppb(w) to 250 ppm(w) with correlation coefficient of at least 0.999 and detection limit of 50 ppb(w) . Spike recoveries from 500 ppb(w) to 250 ppm(w) for all analytes range from 96 to 102%.

Tandem sulfur chemiluminescence and flame ionization detection with planar microfluidic devices for the characterization of sulfur compounds in hydrocarbon matrices.

The detection of sulfur compounds in different hydrocarbon matrices, from light hydrocarbon feedstocks to medium synthetic crude oil feeds provides meaningful information for optimization of refining processes as well as demonstration of compliance with petroleum product specifications. With the incorporation of planar microfluidic devices in a novel chromatographic configuration, sulfur compounds from hydrogen sulfide to alkyl dibenzothiophenes and heavier distributions of sulfur compounds over a wide range of matrices spanning across a boiling point range of more than 650°C can be characterized, using one single analytical configuration in less than 25min. In tandem with a sulfur chemiluminescence detector for sulfur analysis is a flame ionization detector. The flame ionization detector can be used to establish the boiling point range of the sulfur compounds in various hydrocarbon fractions for elemental specific simulated distillation analysis as well as profiling the hydrocarbon matrices for process optimization. Repeatability of less than 3% RSD (n=20) over a range of 0.5-1000 parts per million (v/v) was obtained with a limit of detection of 50 parts per billion and a linear range of 0.5-1000 parts per million with a correlation co-efficient of 0.998.

Multidimensional gas chromatography using microfluidic switching and low thermal mass gas chromatography for the characterization of targeted volatile organic compounds.

Volatile organic compounds such as light hydrocarbons, dienes, and aromatic compounds are often encountered in the manufacturing and processing environments of chemical and petrochemical segments. These compounds need to be closely monitored for process optimization, plant maintenance and industrial hygiene purposes. A high throughput analytical approach has been successfully developed and implemented for the accurate measurement of fourteen commonly encountered analytes. The approach incorporates a recently introduced 5-port planar microfluidic device configured for use as a Deans switch for multidimensional gas chromatography. The use of multidimensional gas chromatography allows the elimination of potential chromatographic contaminants with a substantial enhancement of stationary phase selectivity via the use of columns with different separation mechanisms, and the back-flushing of heavier undesired hydrocarbons. A low thermal mass gas chromatographic module was employed in the second dimension of the two-dimensional gas chromatography system and was used to provide independent temperature control, and rapid heating and cooling to meet the high throughput requirements. By successfully combining these concepts, complete analysis of fourteen targeted components can be conducted in less than 120s. Repeatability of retention times for all compounds was found to be less than 0.05% (n=20). Repeatability of area counts at two levels, namely 10ppmv and 1000ppmv over a period of two days was found to be less than 3% (n=20). Apart from methane, which has a detection limit of 0.4ppmv, the rest of the compounds were found to have detection limits of less than 0.2ppmv. Compounds of interest were found to be linear over a range of 500ppbv-3000ppmv with correlation coefficients greater than 0.999.

Temperature-programmable resistively heated micromachined gas chromatography and differential mobility spectrometry detection for the determination of non-sulfur odorants in natural gas.

A portable, fast gas chromatographic method for the direct measurement of the parts per billion level of sulfur-free odorants in commercially available natural gas is introduced. The approach incorporates a resistively heated, temperature-programmable silicon micromachined gas chromatograph that employs a standard capillary column for the fast separation of methyl and ethyl acrylate from the natural gas matrix. The separation approach is coupled to a micromachined differential mobility detector to enhance analyte detectability, and the overall selectivity obtained against the matrix is described. A complete analysis can be conducted in less than 70 s. Furthermore, these two compounds can be measured accurately in the presence of other common volatile sulfur-based odorants such as alkyl mercaptans and alkyl sulfides. Repeatability of less than 3% RSD (n = 20) over a range from 0.5 to 5 ppm was obtained with a limit of detection for the target compounds at 50 ppb (v/v) and a linear range from 0.5 to 50 ppm with a correlation coefficient of at least 0.997.

Multidimensional gas chromatography for the characterization of permanent gases and light hydrocarbons in catalytic cracking process.

An integrated gas chromatographic system has been successfully developed and implemented for the measurement of oxygen, nitrogen, carbon monoxide, carbon dioxide and light hydrocarbons in one single analysis. These analytes are frequently encountered in critical industrial petrochemical and chemical processes like catalytic cracking of naphtha or diesel fuel to lighter components used in gasoline. The system employs a practical, effective configuration consisting of two three-port planar microfluidic devices in series with each other, having built-in fluidic gates, and a mid-point pressure source. The use of planar microfluidic devices offers intangible advantages like in-oven switching with no mechanical moving parts, an inert sample flow path, and a leak-free operation even with multiple thermal cycles. In this way, necessary features such as selectivity enhancement, column isolation, column back-flushing, and improved system cleanliness were realized. Porous layer open tubular capillary columns were employed for the separation of hydrocarbons followed by flame ionization detection. After separation has occurred, carbon monoxide and carbon dioxide were converted to methane with the use of a nickel-based methanizer for detection with flame ionization. Flow modulated thermal conductivity detection was employed to measure oxygen and nitrogen. Separation of all the target analytes was achieved in one single analysis of less than 12 min. Reproducibility of retention times for all compounds were found to be less than 0.1% (n=20). Reproducibility of area counts at two levels, namely 100 ppm(v) and 1000 ppm(v) over a period of two days were found to be less than 5.5% (n=20). Oxygen and nitrogen were found to be linear over a range from 20 ppm(v) to 10,000 ppm(v) with correlation coefficients of at least 0.998 and detection limits of less than 10 ppm(v). Hydrocarbons of interest were found to be linear over a range from 200 ppb(v) to 1000 ppm(v) with correlation coefficients of greater than 0.999 and detection limits of less than 100 ppb(v).

Temperature-programmable low thermal mass silicon micromachined gas chromatography and differential mobility detection for the fast analysis of trace level of ethylene oxide in medical work place atmospheres.

A portable, fast gas chromatographic method for the direct measurement of part-per-billion level of ethylene oxide in medical work place atmospheres is introduced. Ethylene oxide is a chemical of significance in life science for its critical role as a highly effective sterilizing agent for heat sensitive surgical instruments. However, ethylene oxide is highly flammable, a suspected human carcinogen, is mutagenic, and henceforth, requires close monitoring. The approach incorporates a temperature-programmable silicon micromachined gas chromatograph for the fast separation of ethylene oxide from airborne organic interferences. The separation approach is hyphenated to a micromachined differential mobility detector, improving targeted analyte detection, and enhancing the overall selectivity obtained. A complete analysis can be conducted in less than 60s. Further, ethylene oxide in the matrix mentioned can be measured directly with low possibility of false positives and without the need for any sample pre-treatment, such as pre-concentration or derivatization. A relative precision of less than 5% RSD (n=20) over a range from 5 parts per billion (v/v) to 500 parts per billion (v/v) was obtained.

Multi-dimensional gas chromatography with a planar microfluidic device for the characterization of volatile oxygenated organic compounds.

Oxygenated compounds like methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetaldehyde, crotonaldehyde, ethylene oxide, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and 2-chloromethyl-1,3-dioxolane are commonly encountered in industrial manufacturing processes. Despite the availability of a variety of column stationary phases for chromatographic separation, it is difficult to separate these solutes from their respective matrices using single dimension gas chromatography. Implemented with a planar microfluidic device, conventional two-dimensional gas chromatography and the employment of chromatographic columns using dissimilar separation mechanisms like that of a selective wall-coated open tubular column and an ionic sorbent column have been successfully applied to resolve twelve industrially significant volatile oxygenated compounds in both gas and aqueous matrices. A Large Volume Gas Injection System (LVGIS) was also employed for sample introduction to enhance system automation and precision. By successfully integrating these concepts, in addition to having the capability to separate all twelve components in one single analysis, features associated with multi-dimensional gas chromatography like dual retention time capability, and the ability to quarantine undesired chromatographic contaminants or matrix components in the first dimension column to enhance overall system cleanliness were realized. With this technique, a complete separation for all the compounds mentioned can be carried out in less than 15 min. The compounds cited can be analyzed over a range of 250 ppm (v/v) to 100 ppm (v/v) with a relative standard deviation of less than 5% (n=20) with high degree of reliability.

Ultra-trace level analysis of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate by gas chromatography with multi-mode inlet, and flame ionization detection.

Steam condensate water treatment is a vital and integral part of the overall cooling water treatment process. Steam condensate often contains varying levels of carbon dioxide and oxygen which acts as an oxidizer. Carbon dioxide forms corrosive carbonic acid when dissolved in condensed steam. To neutralize the harmful effect of the carbonic acid, volatile amine compounds such as morpholine, cyclohexylamine, and diethylaminoethanol are often employed as part of a strategy to control corrosion in the water treatment process. Due to the high stability of these compounds in a water matrix, the indirect addition of such chemicals into the process via steam condensate often results in their presence throughout the process and even into the final product. It is therefore important to understand the impact of these chemicals and their fate within a chemical plant. The ability to analyze such compounds by gas chromatography has historically been difficult due to the lack of chromatographic system inertness at the trace level concentrations especially in an aqueous matrix. Here a highly sensitive, practical, and reliable gas chromatographic approach is described for the determination of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate at the part-per-billion (ppb) levels. The approach does not require any sample enrichment or derivatization. The technique employs a multi-mode inlet operating in pulsed splitless mode with programmed inlet temperature for sample introduction, an inert base-deactivated capillary column for solute separation and flame ionization detection. Chromatographic performance was further enhanced by the incorporation of 2-propanol as a co-solvent. Detection limits for morpholine, cyclohexylamine, diethylaminoethanol were established to be 100 ppb (v/v), with relative standard deviations (RSD) of less than 6% at the 95% confidence level (n=20) and a percent recovery of 96% or higher for the solutes of interest over a range of 0.1-100 ppm (v/v). A complete analysis can be conducted in less than 10 min.

Analysis of part-per-billion level of arsine and phosphine in light hydrocarbons by capillary flow technology and dielectric barrier discharge detector.

A practical gas chromatographic procedure has been developed and implemented for the measurement of arsine and phosphine in hydrocarbons such as propylene at the part-per-billion level. The successful measurement of arsine and phosphine at the level mentioned was attained by incorporating a large volume injection technique to increase the mass of solutes delivered for sensitivity improvement, capillary flow technology to keep the matrix from entering the detector by either back-flushing through the inlet vent, or by heart-cutting if required, and dielectric barrier discharge detector operating in argon mode for sensitivity enhancement, as well as offering improved selectivity towards the solutes cited. Using the technique described a complete analysis can be conducted in less than 4 min. A relative standard precision of less than 1.7% was achieved with repeated injections at the concentration level of 25 and 125 ppb (v/v) each of arsine and phosphine in nitrogen with a practical detection limit at the 5 ppb (v/v) level. Correlation coefficients of greater than 0.9999 were obtained for arsine and phosphine over a range from 10 to 2500 ppb (v/v). The analytical methodology was proven to be reliable in continuous operation during the first 6 months of deployment.

Practical method for the measurement of Alkyl mercaptans in natural gas by multi-dimensional gas chromatography, capillary flow technology, and flame ionization detection.

Volatile sulfur compounds such as alkylmercaptans are undesired impurities in natural gas streams. As a result, natural gas treatment and purification services are essential in many industries that utilize natural gas either as a fuel or in a chemical process. While there are many analytical methods that can be employed for the measurement of mercaptans, a simple, practical, and easy-to-implement method is required for remote field deployment. An analytical method, based on multi-dimensional gas chromatography (MDGC), capillary flow technology and flame ionization has been successfully developed for the application described. Results based on the technique showed alkylmercaptans can be accurately measured with a minimum detection limit of 200 ppb (v/v) or better, a linear range of up to 100 ppm (v/v), and a relative standard deviation (n=10) of 1.2% or less were obtained by manual injection with a total sample-to-sample analysis time of less than 15 min.

Assessment of asphalt concrete acoustic performance in urban streets.

Geo-referenced close proximity rolling noise and sound absorption measurements are used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of streets with low speed limits is presented for a reference speed of 50 km/h. Different pavements and pavement conditions, common in urban streets, are analyzed: dense and semidense asphalt concrete, with Spanish denomination D-8 and S-12, respectively, and on the other hand, dense pavement at the end of its service life (D-8(*)). From the acoustics point of view, the most favorable surface, by more than 4 dB(A) compared with the S-12 mix, is the smoothest surface, i.e., the D-8 mix, even though it presents a minor absorption coefficient in normal incidence. Noise levels from dense surfaces (D-8) increase significantly over time, principally due to the appearance of surface defects such as cracks and ruts. Longitudinal variability of the close proximity tire/pavement noise emission and surface homogeneity are also analyzed.

Capillary flow technology with multi-dimensional gas chromatography for trace analysis of oxygenated compounds in complex hydrocarbon matrices.

By employing multi-dimension gas chromatography with capillary flow technology in combination with highly selective capillary columns and a pressurized liquid injection system, light oxygenated compounds such as methanol, ethanol, n-propanol, 2-propanol, and n-butanol in the presence of either light hydrocarbon, heavy hydrocarbon, or aromatic matrices can be measured accurately with minimal possibility of a false positive. Using this technique, a detection limit of at least 0.20 ppm (w/w) with a linear correlation coefficient greater than 0.9993 over a range from 0.5 ppm to 600 ppm (w/w) and a relative standard deviation of greater than 2.7% are achieved for the solutes tested. The technique can also be effective for the measurement of other classes of oxygenated compounds such as ethers, aldehydes, and ketones. Another added benefit for the implementation of capillary flow technology is the capability to conduct column back-flushing, where heavier, undesired solutes in a sample can be back-flushed from the chromatographic system to improve system cleanliness and sample throughput.