Portable Photometer Research Articles

STUDIES ON THE DETERMINATION OF THE TOTAL HARDNESS OF THE DRINKING WATER COMING FROM THE "FÂNTÂNILE RECI" SPRING IN MARAMUREŞ

The paper showcases research conducted in order to determine the total hardness of the drinking water coming from the "Fântânile Reci" spring, located at the edge of the DN18 road, at the end of the Mara town, in Maramures, Romania. A HI97735 advanced portable photometer was used for this experiment. The photometer can perform low, medium and high range measurements of the total hardness of the water samples. The counter comes equipped with a superior optical system which uses a reference detector and a narrowband interference filter used for extremely quick and repeatable measurements. The values obtained as the result of the experiment are: 204 mg/l CaCO 3 (Total Hardness MR), 15,2 °E, 12,2°dH and 21,7°f. The LED light sources are superior compared to the tungsten lamps. LED lights are more efficient, providing more light while using less energy, and they produce little heat, which could otherwise affect the electrical balance.

Aerosol characteristics over the Arctic seas of Eurasia: results of measurements in 2018 and average spatial distribution in the summer-autumn periods of 2007–2018

In August-September 2018, on the route of the expedition “Arctic-2018” (R/V “Akademik Tryoshnikov”) in the Arctic Ocean we carried out the following cycle of measurements of aerosol characteristics: aerosol optical depth (AOD) of the atmosphere in the wavelength range of 0.34–2.14 μm, number concentrations of particles with diameters of 0.4–10 μm, and mass concentration of absorbing substance (black carbon) in the near-ground layer. The optical and microphysical characteristics of aerosol were measured using portable sun photometer SPM, photoelectric particle counter AZ-10, and aethalometer MDA. Analysis of the measurements showed that aerosol and black carbon concentrations are maximal in the atmosphere of the Barents Sea and especially in its southern part, subject to outflows of fine aerosol from the north of Europe. The average aerosol characteristics near Kola Peninsula had been 7.2 cm–3 for aerosol concentration, 167 ng/m3 for black carbon concentration, and 0.16 for AOD (0.5 μm). To estimate the specific features of the spatial variations in aerosol over the Arctic seas of Russia, we generalized the measurements in nine (2007–2018) expeditions. All aerosol characteristics are found to decrease from west toward east in the average spatial distribution. The average concentrations of aerosol are 3.5 cm–3, black carbon concentrations are 41.2 ng/m3, and AOD (0.5 μm) values are 0.080 over the Barents Sea; and they decrease to 1.96 cm–3, 24.3 ng/m3, and 0.039 respectively over the East Siberian Sea. The decreasing tendency in the northeastern direction is noted in more detailed latitude-longitude distributions of aerosol characteristics in the atmosphere over the Barents and Kara Seas.

AMPERO-PHOTOMETRIC METHOD (APM) FOR THE DETERMINATION OF COLORED SOLUTION CONCENTRATION USING A LIGHT DEPENDENT RESISTOR (LDR)

A simple, portable photometer depending on the intensity of the light that passes through a colored solution was designed. Through it, the measured light intensity parameter is converted to an electrical current density, which flow in a circuit of light dependent resistor (LDR). The suggested device is characterized by that it does not depend on the absorptivity at a specific wavelength, but depends on the intensity of the light passing through the sample only. The merits of this method are low power, high sensitivity, and very low cost. The proposed method is in excellent harmony with the determination of the concentration of colored solutions by spectrophotometr.

Magnetic solid-phase extraction and a portable photocolourimeter using a multi-colour light emitting diode for on-site determination of nitrite

In this study, a new, simple, cheap, fast method for on-site determination of trace amount of nitrite in atmospheric liquids and surface water is suggested. The proposed method is based on a combination of magnetic solid phase extraction with a designed portable photometer based on light-emitting diodes. The colour reaction of nitrite was carried out with 4-nitroaniline in acidic medium and then coupled with naphth-1-ol in alkaline medium to form an azo product. The reaction and extraction conditions (e.g., acidity for diazotization and alkalinity for naphth-1-ol coupling, and other reagent concentrations, amount of sorbent, desorption solvent type and volume, etc.) were optimized. Under the optimal conditions, the calibration graph was linear in the range of 0.01–0.3 mg L−1 with the limit of detection (LOD) of 0.0013 mg L−1. The enhancement factor was about 110. Relative standard deviations (RSDs) for the extraction of 0.03 and 0.1 mg L−1 of nitrite were obtained 2.49% and 5.34% for five replicates, respectively. The proposed method was able to analyse nitrite ion in water samples with satisfactory recovery ranged from 87% to 103%.

Light exposure at night and sleep quality in bipolar disorder: The APPLE cohort study

BackgroundSleep disturbance in bipolar disorder (BD) is common and is associated with a risk for mood episode recurrence. Thus, it is important to identify factors that are related to sleep disturbance in BD. This cross-sectional study investigated the association between exposure to light at night (LAN) and sleep parameters in patients with BD. MethodsThe sleep parameters of 175 outpatients with BD were recorded using actigraphy at their homes for seven consecutive nights and were evaluated using the Insomnia Severity Index (ISI). The average LAN intensity in the bedroom during bedtime and rising time was measured using a portable photometer, and the participants were divided into two groups: “Light” (≥5 lx) and “Dark” (<5 lx). The association between LAN and sleep parameters was tested with multivariable analysis by adjusting for potential confounder such as age, gender, current smoker, mood state, day length, daytime light exposure, and sedative medications. ResultsAfter adjusting for potential confounder, the actigraphy sleep parameters showed significantly lower sleep efficiency (mean, 80.1%vs. 83.4%; p = 0.01), longer log-transformed sleep onset latency (2.9 vs. 2.6 min; p = 0.01), and greater wake after sleep onset (51.4 vs. 41.6 min; p = 0.02) in the Light group than in the Dark group. Whereas, there were no significant differences in the ISI scores between the groups. LimitationsThis was a cross-sectional study; therefore, the results do not necessarily imply that LAN causes sleep disturbance. ConclusionsReducing LAN exposure may contribute to improved sleep quality in patients with BD.

Serum Retinol and Anemia in Women of Reproductive Age from Saint-Marc, Haiti (P02-008-19)

ObjectivesThe objective was to assess serum retinol concentration in women of reproductive age from Haiti by HPLC and a portable photometer, as well as the presence of anemia and hemoglobin (Hb) concentration. MethodsCross-sectional comparative study design. Women of reproductive age from the program to improve food security in Haiti (AKOSAA) were eligible to participate. Weight and height were measured and Body Mass Index (BMI) was calculated. A sample of venous blood (5 mL) was collected to assess serum retinol (SR) using HPLC and a portable photometer. Hemoglobin concentration was determined using HemoCue and C-reactive protein (Spinreact E-17176, St Esteve de Bas), was used as a marker of inflammation. ResultsAge range among participants (n = 163) was 15–50 years old. Low weight was identified in15% (n = 24) of enrolled women according to BMI. Vitamin A deficiency (VAD) was identified in 55% (n = 90) of the study population according to serum retinol assessed by HPLC (reference method) versus 26.4% identified using the portable photometer (weighted Kappa = 0.10), which is considered extremely poor. Severe VAD was not found but mild and severe VAD was identified in 38.7% and 16% of women, respectively. When the difference and average of measurements of both methods were compared, bias was 0.20 (IC 95%: 0.14, 0.27). Lin’s concordance coefficient (ρc), an analysis of accuracy and precision that assesses how every pair of observations falls over the line of identity (45°), was extremely poor, because it was found below 0.90 (ρc = 0.19). On the other hand, 45% (n = 73) of participants had anemia (Hb < 12 g/dL). No inflammation was observed, since C-reactive protein was below 6 mg/L. ConclusionsIn Haiti VAD as well as anemia were found to be a public health problem. As long as the socioeconomical situation does not substantially improve in this región, supplementation policies and food fortification must be implemented to be able to fight hidden hunger. Funding SourcesInternational Atomic Energy Agency (IAEA) CRP contract No. 18,223. Sight and Life donated the iCheckFluoro® equipment and reagents.

Determinan Anemia Ibu Hamil Trimester II dan III di Indonesia (Analisis Data Riset Kesehatan Dasar)

&lt;p&gt;Anemia in pregnant women affects the occurrence of antepartum hemorrhage, postpartum hemorrhage, infection, obstacle to fetal growth and development, and prematurity. The aim of this study is to determine the determinants of anemia in second and third trimester pregnant women in Indonesia. The study is used secondary data of Basic Health Research year of 2013, a cross-sectional study design. The population of this study is pregnant women who were selected as respondents in the Basic Health Research year of 2013. The sample of this study consisted of 379 pregnant women, with a gestational age of 7-41 weeks. HB levels of pregnant women were examined using a portable Hemocue photometer. Independent variables is collected by interview. To determine the anemia determinant factors of pregnant women using Cox regression analysis. The results of this study show the prevalence of anemia in second and third trimester pregnant women in Indonesia is 41.2%. The factors that become anemia determinants in second and third trimester pregnant women in Indonesia are PR parity 1.42 (95% CI: 1.02-1.97), and ANC PR 1.65 (95% CI: 1.20-2,28). Pregnant women who carry out ANC according to standards can reduce the risk of anemia during pregnancy.&lt;/p&gt;

Light pollution at Bosscha Observatory, Indonesia

To know the level of light pollution due to human activities, we performed sky brightness measurements at Bosscha Observatory, Indonesia (107°36E; 6°49’S, 1300 m above the sea level) during years 2011-2012 by using a portable photometer at zenith direction. From 400 records of night, we obtained that average and maximum sky brightness were 17.75±0.86 mag/arcsec sq. and 19.14±0.79 mag/arcsec sq., respectively. Cities around the Observatory, that are Bandung and Lembang, clearly give a strong contribution to light pollution. The patches of Milky Way galaxy are disappearing from the sky. Higher maximum sky brightness occurred after midnight. Brightness values before midnight were 17.83±0.83 mag/arcsec sq. on average and 18.98±0.78 mag/arcsec sq. at maximum, with average temperature of 18.8±1.3 C. The average and maximum magnitudes after midnight were 17.67±0.88 mag/arcsec sq. and 19.41±1.24 mag/arcsec sq. with average temperature of 17.1±1.6 C. Sky brightness depends on Moon age and monthly seasonal variations, but it has no relation with Earth eccentricity.

User-Based Photometer Analysis of Effluent from Advanced Nitrogen-Removal Onsite Wastewater Treatment Systems

Advanced nitrogen-removal onsite wastewater treatment systems (OWTS) are used to reduce total nitrogen (N) levels in domestic wastewater. Maintaining system performance requires regular monitoring and in situ rapid tests can provide an inexpensive option for assessing treatment performance. We used a portable photometer to measure ammonium and nitrate concentrations in final effluent from 46 advanced N-removal OWTS, sampling each site at least three times in 2017. To assess photometer accuracy, we compared measurements made using the photometer with those determined by standard laboratory methods using linear regression analysis and a two-tailed t test to compare regression parameters to those for a perfect linear relationship (slope = 1, intercept = 0). Our results show that photometer-based analysis reliably estimates inorganic N (ammonium and nitrate) concentration in field and laboratory settings. Photometer-based analysis of the sum of inorganic N species also consistently approximated the total N concentration in the final effluent from the systems. A cost-benefit analysis indicated that the photometer is a more cost-effective option than having samples analyzed by commercial environmental testing laboratories after analysis of 8 to 33 samples. A portable photometer can be used to provide reliable, cost-effective measurements of ammonium and nitrate concentrations, and estimates of total N levels in advanced N-removal OWTS effluent. This method can be a viable tool for triaging system performance in the field, helping to identify systems that are not functioning properly and may need to be adjusted or repaired by an operation and maintenance service provider in order to meet treatment standards.

A Simplistic Portable LED-Based Photometer for In Situ Determination of Copper in Sugarcane Spirits

A low-cost and portable LED-based photometer was developed and applied for in situ determination of copper in sugarcane spirit. The determination was based on the chelation reaction between copper(II) and cuprizone (bis(cyclohexanone)oxalyldihydrazone). After optimizing the best experimental variables, a dynamic linear range to determine copper(II) was linear from 1.0 to 12.0 mg L−1 (r2 = 0.999) with the limits of detection and quantification of 0.20 and 0.70 mg L−1, respectively. The recovery of copper ranged from 96.5 to 104.4%. The paired t test was performed, and the results agreed at 95% level of confidence. The analytical method LED-based photometer demonstrated that it can be employed to determine copper in sugarcane spirit for quality purpose, e.g., small rural producers can evaluate the drink quality before bottling due to the easy handling, portability, fast response, and low-cost of the materials used.

Atmospheric total ozone column evaluation with a smartphone image sensor

ABSTRACTA new method for quantifying the total ozone column (TOC) using a smartphone image sensor has been developed and validated. The TOC has been evaluated for relatively cloud free days at high air masses for solar zenith angles between 49.7° and 76.7° at a sub-tropical site. The method is based on the evaluation of the direct solar irradiances at 305 and 312 nm using the red colour pixel values of the solar disc recorded at these wavelengths by a smartphone camera. Narrow bandpass filters of 2 nm full width at half maximum at each of the two wavelengths were used in turn placed over the camera sensor to directly image the solar disc. The calibration of the pixel values of the solar disc to provide the direct solar irradiances at each of these two wavelengths allowed evaluation of the TOC calibrated to a portable sun photometer. The root mean square error (RMSE) for the smartphone-derived ozone values calibrated to corresponding values from a portable sun photometer was 4.3 Dobson Units (DU). The validation measurements for the smartphone-derived ozone values provided an average residual of 3.5% (up to a maximum of 11%) compared to the corresponding portable sun photometer values, with an RMSE of 8.4 DU during days of intermittent inclement weather conditions. The evaluation of the TOC based on a widely available device such as a smartphone has the potential to increase current citizen science initiatives valued by the general public and school-aged learners by enhancing knowledge and awareness of ozone and the resulting influences on the solar ultraviolet environment.

In Situ Determination of Urea in Milk Employing a Portable and Low-Cost LED Photometer

A low-cost and portable LED photometer was developed and applied for the in situ determination of urea in milk. The determination was based on Berthelot’s reaction. After optimization, the best experimental variables, the detection limit and quantification limit were 1.8 × 10−4 and 8.0 × 10−4 mol L−1, respectively. The percentage recovery varied between 95.6 and 105%. The paired t test was performed for the cow and goat milk determination and the results agreed at a 95% level of confidence for the in situ determination. Supported by the results, the analytical method based on LED photometer demonstrated that it can be employed for urea determination in food production for quality purpose, and small rural producers can evaluate the quality of herd feeding due to the easy handling, portability, fast instrumental response, and low cost of the materials used.

Malaria Is More Prevalent Than Iron Deficiency among Anemic Pregnant Women at the First Antenatal Visit in Rural South Kivu.

Anemia is common during pregnancy and is associated with poor outcomes. Objectives were not only 1) to determine the prevalence of anemia and iron deficiency (ID) but also 2) to identify other factors associated with anemia in pregnant women from South Kivu province, in the eastern Democratic Republic of Congo. Between December 2013 and March 2014, 531 women attending the first antenatal visit in their second trimester of pregnancy were recruited. Sociodemographic, clinical, and biological data were collected. Hemoglobin (Hb) was determined by a portable photometer (Hemocue® Hb201+), and anemia was defined as altitude-adjusted Hb < 110 g/L. ID was defined as serum ferritin < 15 μg/L adjusted for inflammation status (C-reactive protein [CRP] > 5 mg/L and/or α-1-acid glycoprotein > 1 g/L) whereas hypoalbuminemia was defined as serum albumin < 35 g/L. A Giemsa-stained blood smear was used to diagnose malaria. The median age (interquartile range ) was 25.5 (21.1-31.3) years, with anemia in 17.6% and ID in 8%. Malaria was present in 7.5% and hypoalbuminemia among 44%. Soluble transferrin receptor concentration was higher in the presence of inflammation and/or malaria. In the final logistic regression model, factors independently associated with anemia were malaria (adjusted odds ratio [aOR]: 11.24 (4.98-25.37) P < 0.001), hypoalbuminemia [aOR: 2.14 (1.27-3.59); P = 0.004] and elevated CRP [aOR: 1.94 (1.10-3.45); P = 0.022]. ID was not highly prevalent and not associated with anemia in our population. Effective control of anemia during pregnancy in this region should consider fighting malaria and other infectious diseases in combination with measures to improve women's nutrition, both before and during pregnancy.

A novel methodology to determine volcanic aerosols optical properties in the UV and NIR and Ångström parameters using Sun photometry

AbstractRemote volcanic aerosol optical depth (AOD) observations of Mount Etna summit and distal bulk plume have been carried out between 14 and 20 July 2016 in the framework of the EPL‐RADIO project. Ultraviolet (UV) and near‐infrared (NIR) AODs were measured using a Microtops‐II Ozone Monitor (MIIOM) Sun photometer, using a Langley plot (LP) instrumental calibration routine. Ozone‐corrected UV AODs at 320 nm are derived for the first time with a Microtops, thus extending the exploitable spectral band range of portable photometers to shorter wavelengths. The new UV AODs have theoretical uncertainties &lt;±0.035 (±12%), dominated by LP calibration errors. Using UV and NIR AODs, the Ångström coefficients have been derived. The UV AODs and Ångström exponents have been compared, at background conditions, to colocated Cimel Sun photometer observations. A root‐mean‐square deviation of 0.03 (13%) for the UV AOD is found for this comparison, thus in agreement with estimated theoretical uncertainties. The MIIOM Ångström exponent estimations are found consistent with Cimel observations, even if with an average overestimation of 17.5%, mainly due to negative biases (−0.02/−21%) of NIR AODs. Results of quasi‐simultaneous characterization of proximal and distal plume (7 km from craters), for 20 July 2016, are shown. During the measurements, brownish ash puffs were visible. While proximal and distal plumes were observed within approximately 1 h, their Ångström exponent varied significantly (mean values: −0.30±0.22 and 1.16±0.33, for the proximal and distal plumes). These results indicate quick sedimentation of ash particles and show the potential of this new retrieval technique to characterize volcanic aerosols.

Vitamin A supplementation and childhood morbidity from diarrhea, fever, respiratory problems and anemia in sub-Saharan Africa

Vitamin A supplementation and childhood morbidity from diarrhea, fever, respiratory problems and anemia in sub-Saharan Africa Samson Gebremedhin School of Public and Environmental Health, Hawassa University, Hawassa, Ethiopia Background: Systematic reviews consistently indicated that vitamin A supplementation (VAS) (100,000&ndash;200,000 international unit [IU] semiannually) to children aged 6&ndash;59&nbsp;months substantially reduces all-cause child mortality. Yet, its effect on morbidity is inconsistent and its contribution to the reduction of anemia has not been sufficiently explored.Objective: The objective of this study was to assess the association between routine VAS (100,000 IU for children aged 6&ndash;11&nbsp;months and 200,000 IU for children aged 1&ndash;5&nbsp;years) and the occurrence of common childhood illnesses (fever, diarrhea, acute respiratory infection [ARI] and anemia) in preschool children in sub-Saharan Africa (SSA).Methods: The analysis was made based on the data of 28 demographic and health surveys (DHSs) conducted in SSA since 2010. The data of 152,406 children were included. The VAS status in the preceding 6&nbsp;months and the occurrence of the illnesses in the past 2&nbsp;weeks were determined based on the information given by the caregivers. The hemoglobin level was determined using a portable photometer. Data were analyzed using mixed-effects logistic regression model. The outputs were provided using adjusted odds ratio (AOR) with the respective 95% confidence intervals (CIs). The practical significance of the association was measured via Cohen&rsquo;s effect size (d).Results: The coverage of VAS was 56.3% (95% CI: 56.1&ndash;56.5). VAS was modestly associated with increased odds of fever (AOR=1.12 [95% CI: 1.09&ndash;1.15]), diarrhea (AOR=1.09 [95% CI: 1.05&ndash;1.13]) and ARI (AOR=1.18 [95%: 1.12&ndash;1.24]). Conversely, in the supplemented children, the odds of anemia were reduced by 10.1% (95% CI: 7.0&ndash;13.1). All the associations translated into trivial effect sizes (d&lt;0.2).Conclusion: VAS is associated with an inconsequential increase in the occurrence of common childhood ailments. Keywords: vitamin A supplementation, diarrhea, fever, acute respiratory infection, anemia, hemoglobin, demographic and health survey, sub-Saharan Africa

Sky brightness and twilight measurements at Jogyakarta city, Indonesia

The sky brightness measurements were performed using a portable photometer. A pocket-sized and low-cost photometer has 20 degree area measurement, and spectral ranges between 320-720 nm with output directly in magnitudes per arc second square (mass) unit. The sky brightness with 3 seconds temporal resolutions was recorded at Jogyakarta city (110° 25’ E; 70° 52’ S; elevation 100 m) within 136 days in years from 2014 to 2016. The darkest night could reach 22.61 mpass only in several seconds, with mean value 18.8±0.7 mpass and temperature variation 23.1±1.2 C. The difference of mean sky brightness between before and after midnight was about -0.76 mpass or 2.0 times brighter. Moreover, the sky brightness and temperature fluctuations were more stable in after midnight than in before midnight. It is suggested that city light pollution affects those variations, and subsequently duration of twilight. By comparing twilight brightness for several places, we also suggest a 17° solar dip or about 66 minutes before sunrise for new time of Fajr prayer.

“Prospera” Program impact on hemoglobin concentration in children less than five years old from San Luis Potosí State

ObjectiveTo assess the “PROSPERA” program impact over hemoglobin concentrations in a 14‐month follow‐up panel of children less than five years old.MethodsA follow up was realized in 400 and 325 children from 1 to 3 years old beneficiaries of PROSPERA program and controls respectively. For hemoglobin measurement a capillary blood sample was obtained from ring finger and determined through a HemoCue portable photometer. Cutoff criteria for anemia were the proposed by the WHO, adjusting by attitude using Cohen &amp; Hass algorithms. Hemoglobin cutoff value was as follows: 110g/l (based on WHO reference).Resultsat the beginning of the study, the anemia prevalence was significantly higher in the PROSPERA group when compared to the control, (41.5 vs 29.6%, p=0.001) this trend was the same during intermediate stage and disappeared at the end of the study. PROSPERA program impact over hemoglobin concentrations was slightly positive. Moreover it was observed that when the time of belonging to the program increased the hemoglobin concentrations also raised.ConclusionsPROSPERA program was capable of increase the hemoglobin concentrations and impact in the anemia prevalence in the beneficiary children. This led us to recommend the intake of iron‐rich foods, along with a more diverse diet promoted by meat –and other foods with heme‐iron‐ introduction (maybe through the supplements provided by the program).Support or Funding InformationSupported by FOMIX SLP. Project: FMSLP‐213‐C02‐208475

Simple Instrumental and Visual Tests for Nonlaboratory Environmental Control.

Proposed are simple and available techniques that can be used for rapid and reliable environmental control specifically of natural water by means of instrumental and visual tests in outdoor conditions. Developed are the chemical colorimetric modes for fast detection of socially dangerous trace impurities in water such as Co(II), Pd(II), and Rh(III) as well as NO2 −-ions and Fe(III) serving as model impurities. Application of portable digital devices and scanner allows estimating the color coordinates and increasing the accuracy and sensitivity of the tests. The combination of complex formation with preconcentration of colored complexes replaces the sensitive but time-consuming and capricious kinetic method that is usually used for this purpose at the more convenient and reliable colorimetric method. As the test tools, the following ones are worked out: polyurethane foam tablets with sorbed colored complexes, the two-layer paper sandwich packaged in slide adapter and saturated by reagents, and polyethylene terephthalate blister with dried reagents. Fast analysis of polyurethane foam tablets is realized using a pocket digital RGB-colorimeter or portable photometer. Express analysis of two-layer paper sandwich or polyethylene terephthalate blister is realized by visual and instrumental tests. The metrological characteristics of the developed visual and instrumental express analysis techniques are estimated.

Aerosol direct radiative forcing in desert and semi-desert regions of northwestern China

The optical properties of dust aerosols were measured using narrow-band data from a portable sun photometer at four desert and semi-desert stations in northwestern China from 2004 to 2007. Ground-based and satellite observations indicated absorbing dust aerosol loading over the region surrounded by eight large-scale deserts. Radiation forcing was identified by using the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model. The ranges of annual mean aerosol optical depth (AOD), Angström exponents, and single-scattering albedo (SSA) were from 0.25 to 0.35, from −0.73 to 1.18, and from 0.77 to 0.86, respectively. The ranges of annual mean aerosol direct radiative forcing values at the top of the atmosphere (TOA), mid-atmosphere, and on the surface were from 3.9 to 12.0, from 50.0 to 53.1, and from −39.1 to −48.1W/m2, respectively. The aerosols' optical properties and radiative characteristics showed strong seasonal variations in both the desert and semi-desert regions. Strong winds and relatively low humidity will lead dust aerosols in the atmosphere to an increase, which played greatly affected these optical properties during spring and winter in northwestern China. Based on long-term observations and retrieved data, aerosol direct radiative forcing was confirmed to heat the atmosphere (50–53W/m2) and cool the surface (−39 to −48W/m2) above the analyzed desert. Radiative forcing in the atmosphere in spring and winter was 18 to 21W/m2 higher than other two seasons. Based on the dust sources around the sites, the greater the AOD, the more negative the forcing. The annual averaged heating rates for aerosols close to the ground (1km) were approximately 0.80–0.85K/day.

Rapid Screening of Oxytetracycline Residue in Fish Muscle by Dispersive Liquid-Liquid Microextraction and Europium-Sensitized Luminescence

A screening protocol was developed for oxytetracycline (OTC) residue in catfish muscle based on dispersive liquid-liquid microextraction (DLLME) and europium-sensitized luminescence (ESL). The analyte was extracted in HCl-ethylenediaminetetraacetic acid (EDTA)-acetonitrile, cleaned up by DLLME in water-acetonitrile-hexane-CH2Cl2, and detected by ESL using a portable luminescence photometer. A threshold was established at T = x 2 − 3σ2, where x 2 and σ2 were mean and standard deviation of ESL signals of catfish muscle samples (n = 20) spiked at 2 μg g−1, the tolerance set by the US Food and Drug Administration (FDA). Among 48 samples randomly spiked with OTC at 0–4 μg g−1, 46 were screened correctly without false negative, and 2 negatives were classified as presumptive positives. This reliable method cut usage of chlorinated solvent to 0.75 mL, reduced cost, and improved sample throughput.