Bidirectional MMWoF-wireless convergence system based on a 1610†nm L-band quantum-dash laser.

We report bidirectional 25/28 GHz millimeter wave (MMW)-over-fiber (MMWoF) and MMWoF-wireless (MMWoF-WL) transmission systems employing a single self-injection locked InAs/InP quantum-dash dual-mode laser (QD-DML) as a MMW source. Besides, we demonstrate the entire system exploiting the challenging mid-L-band wavelength window (1610 nm) to substantiate this source's potential, which exhibits tunability from C- to L-bands, in next-generation optical networks covering these wavelengths' window operations. While exhibiting 28 GHz mode spacing between the two optical carriers of QD-DML, a downstream (DS) transmission of 4.0 Gbaud (8 Gbits/s) quadrature-phase-shift-keying (QPSK) signal is conducted over this carrier. In addition, a simultaneous 2.0 Gbaud (8 Gbits/s) 16-level quadrature amplitude modulation (16-QAM) upstream (US) transmission on a 25 GHz MMW beat-tone is also achieved by exploiting one of the DS optical tones. A rigorous transmission characterization of variable DS and US QPSK/16-QAM data rates over MMWoF (10 km SMF) and MMWoF-WL (10 km SMF and up to 4 m wireless) are performed, showing a strong influence of phase noise on the DS link and hence the receiver sensitivity.

Quantitative analysis of Fuller's earth using laser-induced breakdown spectroscopy and inductively coupled plasma/optical emission spectroscopy.

Fuller's earth, most commonly known as Multani Matti (clay) in Urdu, among its various utilizations is traditionally used in skin care cosmetics, particularly for removing blackheads and to treat oily skin. It is also used for improving skin complexion. In this paper, laser-induced breakdown spectroscopy (LIBS) was effectively employed for the quantitative investigation of various clay samples for their special uses. To get the LIBS spectra with an optimal signal-to-noise as well as for a more robust and accurate analytical investigation, different experimental parameters (laser energy, gate delay time, and the distance between target and focusing lens) were optimized before the experiments on actual samples. The analysis of emission spectra revealed the presence of many different elements, including Al, Ca, Fe, Mg, Mn, Na, K, Li, S, Si, and Zn. The electron number density and plasma temperatures were determined using the Stark broadened line profile and Boltzmann plot method, respectively. To determine the relative concentration of observed elements, we used an integrated intensity ratio method, integrated intensity of every line from all elements, and calibration free (CF)-LIBS. The prevailing condition of local thermodynamic equilibrium during the experimental executions was verified with multiple criteria. The spectral lines used in CF-LIBS were characterized for the influence from the self-absorption phenomenon, but the same was found insignificant. The findings of our LIBS system were found to agree excellently with the outcomes of the inductively coupled plasma/optical emission spectroscopy, thereby yielding a high statistical correlation factor and hence enlighten the significance of LIBS as a safe and reliable tool for elemental analysis of clay samples.

Development of novel MnO2 coated carbon felt cathode for microbial electroreduction of CO2 to biofuels.

Fabrication of superior and cost-effective cathodic materials is vital in manufacturing sustainable microbial electrolysis cells (MECs) for biofuels production. In the present study, a novel manganese dioxide (MnO2) coated felt cathode (Mn/CF) has been developed for MECs using electrodeposition method via potentiostat. MnO2 is considered to encourage exogenous electron exchange and, in this way, improves the reduction of carbon dioxide (CO2). MnO2, as a cathodic catalyst, enhances the rate of biofuel production, electron transfer, and significantly reduces the cost of MECs. A maximum stabilized current density of 3.70 ±â€¯0.5 mA/m2 was obtained in case of MnO2-coated Mn/CF based MEC, which was more than double the non-coated carbon felt (CF) cathode (1.70 ±â€¯0.5 mA/m2). The dual chamber Mn/CF-MEC achieved the highest production rate of acetic acid (37.9 mmol/L) that was significantly higher (43.0%) in comparison to the non-coated CF-MEC. The cyclic voltammograms further verified the substantial enhancement in the electron transfer between the MnO2 coated cathode and microbes. The obtained results demonstrate that MnO2 interacted electrochemically with microbial cells and enhanced the extracellular electron transfer, therefore validating its potential role in biofuel production. The MnO2 coated CF further offered higher electrode surface area and better electron transfer efficiency, suggesting its applicability in the large-scale MECs.

Optimized laser-induced breakdown spectroscopy for the determination of high toxic lead in edible colors.

An optimized laser-induced breakdown spectroscopy (LIBS) system was utilized as a robust tool for the detection of high toxic lead (Pb) in often used edible colors available in local markets. Edible colors are extensively used in different food stuffs and sweet dish items. To attain a highly sensitive LIBS system for the determination of trace amounts of toxic Pb in edible colors and to achieve the best detection limit, various parametric dependence studies were performed. The quantitative determinations were accomplished under the condition of local thermodynamic equilibrium in terms of optically thin plasma. Besides toxic Pb, other elements like Ca, Mg, Fe, and Na were also detected in edible colors. To estimate the concentration of toxic lead in edible colors, calibration curves were plotted by preparing standard samples of different lead concentrations in an edible colors matrix. Results of the LIBS technique were compared with the outcomes of the same samples studied using a standard analytical technique of inductively coupled plasma-optical emission spectroscopy to confirm the contemporary LIBS setup. The color samples were found above the safe permissible level due to the mass of toxic lead. Limit of detection of the LIBS setup was found at 0.86+/-0.03 ppm for toxic lead present in edible color samples.

Rapidly screening of α-glucosidase inhibitors from Dioscorea opposita Thunb. peel based on rGO@Fe3O4 nanocomposites microreactor.

Present study aimed to immobilise the α-glucosidase on suitable supports to construct enzymatic microreactors and their subsequent applicability in efficient inhibitor screening from the Chinese Yam (Dioscorea opposita Thunb.) peel. A type of lamellar and porous composites (rGO@Fe3O4) were synthesised with a facile one-step solvothermal method and employed as carriers to construct enzymatic microreactors for screening α-glucosidase ligand from the Chinese Yam peel in league with the high performance liquid chromatography and mass spectrometry (HPLC-MS). The immobilisation amount of α-glucosidase on rGO@Fe3O4 under the optimised conditions was about 40 µg α-glucosidase/mg carriers. Furthermore, the binding capacities of screened inhibitors, 2,4-dimethoxy-6,7-dihydroxyphenanthrene and batatasin I, were 35.6 and 68.2%, respectively. Hence, considering their high screening efficiency and excellent magnetic separation ability, these as-prepared nanocomposite consisting of rGO and Fe3O4 may be potential supports for the enzyme (such as α-glucosidase) immobilisation for rapid α-glucosidase inhibitors screening from the diverse nature resources.

Simultaneous quantum dash-well emission in a chirped dash-in-well superluminescent diode with spectral bandwidth >700 nm.

We report on the quantitative evidence of simultaneous amplified spontaneous emission from the AlGaInAs/InAs/InP-based quantum-well (Qwell) and quantum-dashes (Qdash) in a multistack dash-in-an-asymmetric-well superluminescent diode heterostructure. As a result, an emission bandwidth (full width at half-maximum) of >700 nm is achieved, covering entire O-E-S-C-L-U communication bands, and a maximum continuous wave output power of 1.3 mW, from this device structure. This demonstration paves a way to bridge entire telecommunication bands through proper optimization of device gain region, bringing significant advances and impact to a variety of cross-disciplinary field applications.

Ameliorative effects of L-carnitine and vitamin E (α-tocopherol) on haematological and serum biochemical parameters in White Leghorn cockerels given ochratoxin A contaminated feed.

1. L-carnitine is a quaternary ammonium compound biologically synthesised from the amino acids methionine and lysine while vitamin E (α-tocopherol) is an important antioxidant. The objective of the present study was to evaluate the ameliorative effects of L-carnitine and vitamin E upon haematological and serum biochemical parameters in ochratoxin A intoxicated birds. 2. Day-old White Leghorn cockerels were acclimatised for 2 d, divided in 12 groups with 20 birds in each group. From d 3 of age, they were given different combinations of ochratoxin A (1.0 and 2.0 mg/kg), L-carnitine (1 g/kg) and vitamin E (200 mg/kg) in feed. Haematological (erythrocyte count, leucocyte count, haemoglobin concentration and haematocrit percentage) and serum biochemical parameters (serum urea, creatinine, albumin, total proteins and alanine aminotransferase) were evaluated. 3. Results confirmed that L-carnitine and vitamin E given alone or combined with 1.0 mg/kg ochratoxin A ameliorated toxin induced alterations in haematological and serum biochemical parameters. This amelioration, however, did not occur when ochratoxin of 2.0 mg/kg was given. 4. L-carnitine and vitamin E in combination have the ability to ameliorate ochratoxin altered haematological and serum biochemical parameters. However, the optimum ratio of L-carnitine + vitamin E, to be used to assure such mitigation of ochratoxin A altered changes in haematological and serum biochemical parameters in cockerels, has yet to be determined. The combination used in this study was indeed sufficient to ameliorate the alterations induced by ochratoxin A up to 1.0 mg/kg feed.

Label free flexible electrochemical DNA biosensor for selective detection of Shigella flexneri in real food samples.

An effective tool for early-stage selective detection of the foodborne bacterial pathogen Shigella flexneri (S. flexneri) is essential for diagnosing infectious diseases and controlling outbreaks. Here, a label-free electrochemical DNA biosensor for monitoring S. flexneri is developed. To fabricate the biosensor, detection probe (capture probe) is immobilized on the surface of poly melamine (P-Mel) and poly glutamic acid (PGA), and disuccinimidyl suberate (DSS) functionalized flexible indium tin oxide (ITO) electrode. Anthraquinone-2-sulfonic acid monohydrate sodium salt (AQMS) is used as a signal indicator for the detection of S. flexneri. The proposed DNA biosensor exhibits a wide dynamic range with concentration of the targets ranging from 1 × 10-6 to 1 × 10-21 molL-1 with a limit of detection (LOD) of 7.4 × 10-22 molL-1 in the complementary linear target of S. flexneri, and a detection range of 8 × 1010-80 cells/ml with a LOD of 10 cells/ml in real S. flexneri sample. The proposed flexible biosensor provides high specificity for the detection of S. flexneri compared to other target signals such as discrete base mismatches and different bacterial species. The developed biosensor displayed excellent recoveries in detecting S. flexneri in spiked food samples. Therefore, the proposed biosensor can serve as a model methodology for the detection of other pathogens in a broad span of industries.

Nanostructured wearable electrochemical and biosensor towards healthcare management: a review.

In recent years, there has been a rapid increase in demand for wearable sensors, particularly these tracking the surroundings, fitness, and health of people. Thus, selective detection in human body fluid is a demand for a smart lifestyle by quick monitoring of electrolytes, drugs, toxins, metabolites and biomolecules, proteins, and the immune system. In this review, these parameters along with the main features of the latest and mostly cited research work on nanostructured wearable electrochemical and biosensors are surveyed. This study aims to help researchers and engineers choose the most suitable selective and sensitive sensor. Wearable sensors have broad and effective sensing platforms, such as contact lenses, Google Glass, skin-patch, mouth gourds, smartwatches, underwear, wristbands, and others. For increasing sensor reliability, additional advancements in electrochemical and biosensor precision, stability in uncontrolled environments, and reproducible sample conveyance are necessary. In addition, the optimistic future of wearable electrochemical sensors in fields, such as remote and customized healthcare and well-being is discussed. Overall, wearable electrochemical and biosensing technologies hold great promise for improving personal healthcare and monitoring performance with the potential to have a significant impact on daily lives. These technologies enable real-time body sensing and the communication of comprehensive physiological information.

Copper oxide nanoflowers/poly-l-glutamic acid modified advanced electrochemical sensor for selective detection of l-tryptophan in real samples.

The main objective of this research work is to develop a low-cost sensor to detect l-tryptophan (L-tryp) in real sample medium based on a modified glassy carbon electrode. For this, copper oxide nanoflowers (CuONFs) and poly-l-glutamic acid (PGA) were used to modify GCE. The prepared NFs and PGA coated electrode was characterized using field emission scanning electron microscope (FE-SEM) with energy dispersive X-ray (EDX) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Furthermore, the electrochemical activity was performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The modified electrode showed excellent electro-catalytic activity towards L-tryp detection in PBS solution at neutral pH 7.0. Based on the physiological pH condition, the proposed electrochemical sensor can detect L-tryp concentration with a linear range of 1.0 × 10-4-8.0 × 10-8 molL-1 with having a detection limit of 5.0 × 10-8 molL-1 and sensitivity of 0.6µA/µMcm2. The selectivity of L-tryp was tested with a mixture of salt and uric acid solution at the above conditions. Finally, this strategy demonstrated excellent recovery value in real sample analysis like milk and urine.

Zinc oxide nanorod/rutin modified electrode for the detection of Thiourea in real samples.

In this work, a novel electrochemical detection strategy was developed based on a metal-organic framework of zinc oxide nanorod nanoparticles and rutin for selective screening of Thiourea as toxic chemicals. The zinc oxide nanorod were synthesized by following direct chemical precipitation methods and characterized by X-ray diffraction and X-ray photoelectron spectroscopy analysis. The surface of modified electrodes was also characterized by field emission scanning electron microscopes, energy-dispersive X-ray spectroscopy, and attenuated total reflectance flourier transform infrared spectroscopy. Furthermore, the electrochemical activity of the developed sensor was tested by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. The modified electrode showed outstanding electro-catalytic activity towards the detection of Thiourea in phosphate buffer saline at a high pH level of 12.0. The proposed sensor showed a linear range of linearity in a concentration ranging from 5.0 × 10-6 - 900 × 10-6 molL-1 and a detection limit of 2.0 × 10-6 molL-1. Moreover, the selectivity of the developed electrochemical sensor was investigated for the detection of Thiourea in the presence of organic compounds and a group of anions. Furthermore, the proposed strategy demonstrated an excellent recovery value in the spiked farmland water and fruit juice sample.

Effect of different egg yolk-based extenders on the quality of ovine cauda epididymal spermatozoa during storage at 4°C.

Cauda epididymal spermatozoa were obtained from testicles collected from abattoir(s). The pooled sperm samples were divided into four aliquots. Each aliquot was washed separately with the buffer of respective extender and finally extended with the four extenders viz. egg yolk-citrate (EYC), egg yolk-citrate-fructose (EYCF), Tris-citric acid-egg yolk-fructose (TCEYF) and egg yolk-Mcillvaine glucose (EYMG) and preserved at 4°C. The per cent sperm motility for EYC, EYCF, TCEYF and EYMG at 0 h was 50.83%, 56.67%, 75.00% and 31.67%, respectively, and at 72 h was 24.17% (EYC), 30.83% (EYCF), 51.67% (TCEYF) and 7.50% (EYMG). The corresponding figures for live sperm count at 0 h was 83.17%, 86.33%, 90.42% and 81.75% and at 72 h was 64.75%, 73.92%, 76.00% and 57.67%. The corresponding figures for mean per cent intact acrosome at 0 h was 95.33%, 95.50%, 90.92% and 97.25% and at 72 h was 86.17%, 83.92%, 77.58% and 86.33%. The sperm motility was significantly (p < 0.05) higher for TCEYF at different h of preservation from 0 h through 72 h. The sperm motility, live sperm count and per cent intact acrosome declined significantly (p < 0.05) with the advancement of storage time in all the four extenders. Our study concluded that TCEYF was best out of the extenders studied for preservation of cauda epididymal spermatozoa after double centrifugation and extension at 4°C up to 72 h of preservation. However, EYCF also has better potential for the preservation of cauda epididymal spermatozoa as viability was in close proximity and acrosomal integrity was higher compared with TCEYF extender.

Deoxynivalenol as a contaminant of broiler feed: intestinal development, absorptive functionality, and metabolism of the mycotoxin.

Deoxynivalenol (DON) has been recently documented to deteriorate intestinal morphology in chickens at dietary doses that are regarded as safe for this species. The present trial was conducted to explore the significance of these morphological changes in relation to intestinal absorptive functionality and DON metabolism. Ross broilers at 7 d of age were fed either a basal diet (0.265 ± 0.048 mg of DON/kg; 0.013 ± 0.001 mg of zearalenone/kg), a low DON diet (1.68 mg of DON/kg; 0.145 ± 0.007 mg of zearalenone/kg), or a high DON diet (12.209 ± 1.149 mg of DON/kg; 1.094 ± 0.244 mg of zearalenone/kg). The DON diets (to variable degrees) progressively decreased the relative density (weight:length) of the small intestine with increasing exposure length, which could be correlated with a decrease in villus height in the small intestine. Short circuit current of the jejunal epithelium, reflecting transport function of the epithelium per unit area, was reduced (P = 0.001) in the birds fed the high DON diet. The increasing dietary level of DON linearly (P = 0.035) increased the length of the jejunum in wk 4 of exposure, resulting in conservation of macronutrient retention. Upon challenging the birds with a fixed amount of DON after wk 5 of exposure, higher (P ≤ 0.033) amounts of DON and the detoxification metabolite (de-epoxy-DON) were found at 5 h postchallenge in the guts of birds raised on the DON diets. The increasing level of previous exposure to DON linearly (P = 0.040) decreased the plasma level of DON in the birds at 1 h postchallenge. The amounts of zearalenone and its analogs in the gut and plasma also followed a trend similar to that for DON. These data suggest that intestines in chickens may adapt to a chronic DON challenge by morphological and functional modifications. The birds having previous exposure to Fusarium mycotoxins showed moderate detoxification coupled with reduced transfer of the mycotoxins to systemic circulation. Some metabolites of zearalenone found in this study were previously unknown for chickens.

Assessing estrogenic chemicals in anchovy and mussel samples from Karachi, Pakistan with the yeast estrogen screen bioassay.

Endocrine disrupting chemicals (EDCs) are introduced into the aquatic environment through industrial and municipal effluents along with urban and agricultural runoffs. Exposure of aquatic organisms to EDCs may lead to hormonal disruption and adverse health effects. The goals of our study were: to collect anchovy and mussel samples from the coastal region of Karachi, to use the yeast estrogen screen (YES) bioassay in estimating xeno-estrogen content in these samples, and to investigate if the bioassay could be used to quantify known amounts of 17ß-estradiol (E2) injected into cod and salmon fillets. Results of the studies showed that mussel estrogenic activity in Karachi decreased in the order of Buleji point 1 (8.91 ± 4.77, mean ± SD) > Paradise point 1 (1.72 ± 0.81) > Paradise point 2 (0.61 ± 0.84) ng E2 equivalents/g wet wt (p < 0.05). By comparison, anchovy estrogenic activity at Korangi/Phitti Creek was much higher than at Manora. Together, these results confirmed previous reports that both Buleji point 1 and Korangi/Phitti Creek were the most contaminated areas of Karachi. The YES bioassay was only a semi-quantitative method in determining the contents of xeno-estrogens in aquatic organisms; it consistently overestimated the amounts of E2 injected into cod and salmon fillets due to additive and/or non-additive interactions between E2 and endogenous estrogens. Nevertheless, the YES bioassay was able to identify the contaminated sites in the coastal region of Karachi.

Recent Biosensors for Detection of Antibiotics in Animal Derived Food.

Antibiotics are extensively employed as bacteriostatic agents for fighting against microbial infection in animals. However, inappropriate doses of antibiotic drugs may result in antibiotic residues in food of animal origin and may cause various side effects on human health. Moreover, the transferor of antibiotic-resistant bacteria to humans through the food chain may induce serious health hazards. Hence, it is vital to develop sensitive and selective methods for rapid screening and regular monitoring of antibiotic residues in animal-derived foods. The conventional different chromatographic and spectroscopic techniques are time-consuming, expensive and require skilled personnel. To overcome such limitations, biosensors have emerged as an innovative approach recently and integrated with nanotechnologies for sensitive, rapid and on-site monitoring of different antibiotic residues in animal origin foods. This mini-review aims to give an overview of the currently available biosensing techniques to detect antibiotic residue in foods.

Graphitic carbon nitride and APTES modified advanced electrochemical biosensor for detection of 17ß-estradiol in spiked food samples.

This work demonstrates a simple and inexpensive electrochemical biosensing pathway for selective and sensitive recognition of 17ß-estradiol (E2) in environmental and food samples. The biosensing system is based on graphitic carbon nitride (g-C3N4) and a conductive polymer 3-aminopropyltriethoxysilane (APTES). The proposed biosensor shows the ability to detect E2 in attomolar levels within a wide linear logarithm concentration range of 1 × 10-6 to 1 × 10-18 mol L-1 with a limit of detection (LOD) of 9.9 × 10-19 mol L-1. The selectivity of the developed biosensor was confirmed by conducting the DPV of similarly structured hormones and naturally occurring substances. The proposed biosensor is highly stable and applicable to detect E2 in the presence of spiked food and environmental samples with satisfactory recoveries ranging from 95.1 to 104.8%. So, the designed electrochemical biosensor might be an effective alternative tool for the detection of E2 and other endogenous substances to attain food safety.

Development of a hematite nanotube and tyramine-based drug carrier against drug-resistant bacteria Klebsiella pneumoniae.

In this study, hematite nanotube (HNT) and tyramine-based advanced nano-drug carriers were developed for inhibiting the growth of Klebsiella pneumoniae (K. pneumoniae). The HNT was synthesized by following the Teflon line autoclaved assisted hydrothermal process and tyramine was incorporated on the surface of the HNT to fabricate the formulated nano-drug. The nano-drug was prepared by conjugating meropenem (MP) on the surface of Tyramine-HNT and characterized using different techniques, such as scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR), etc. Furthermore, the drug-loading efficiency and loading capacity were measured using a UV-vis spectrometer. The pH, amount of Tyr, and HNT required for drug loading were optimized. A controlled and gradual manner of pH-sensitive release profiles was found after investigating the release profile of MP from the carrier drug. The antibacterial activity of MP@Tyramine-HNT and MP was compared through the agar disc diffusion method which indicates that antibacterial properties of antibiotics are enhanced after conjugating. Surprisingly, the MP@Tyramine-HNT exhibits a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of K. pneumoniae lower than MP itself. These results indicate the nanocarrier can reduce the amount of MP dosed to eradicate K. pneumoniae.

A DNA functionalized advanced electrochemical biosensor for identification of the foodborne pathogen Salmonella enterica serovar Typhi in real samples.

An efficient platform for the detection of Salmonella enterica serovar Typhi (S. Typhi) is essential for early-stage diagnosis of typhoid to prevent and contain outbreaks. Here, we fabricated an electrochemical DNA biosensor for selective identification of S. Typhi in real samples. The biosensor has been fabricated by immobilizing an amine labelled S. Typhi specific single-strand capture probe on the surface of gold nanoparticles (AuNP) and poly cysteine (P-Cys) modified screen-printed electrode. Differential pulse voltammetry (DPV) of anthraquinone-2-sulfonic acid monohydrate sodium salt (AQMS) as a signal indicator was monitored to detect S. Typhi by hybridization of target DNA with the probe DNA. The fabricated biosensor shows a detection range of 1 × 10-6 to 1 × 10-22 molL-1 with a LOD of 6.8 × 10-25 molL-1 in S. Typhi complementary linear target and 1.8 × 105 to 1.8 CFUml-1 with a LOD of 1 CFUml-1 in a real S. Typhi sample. The biosensor shows excellent discrimination ability to some bases mismatched and different bacterial cultures (same and distant genera). The most beneficial points of the proposed DNA biosensor are the lower limit of detection and the ability to reuse the biosensor more than 6 to 7 times. In addition, the practicability of the biosensor was investigated via detecting S. Typhi in blood, poultry feces, egg, and milk whereby excellent recoveries ranging from 96.54 to 103.47% were demonstrated indicating that this biosensor might be the most promising diagnostic tool for monitoring S. Typhi in clinical and food samples.

Effect of the number of stacking layers on the characteristics of quantum-dash lasers.

A theoretical model is evaluated to investigate the characteristics of InAs/InP quantum dash (Qdash) lasers as a function of the stack number. The model is based on multimode carrier-photon rate equations and accounts for both inhomogeneous and homogeneous broadenings of the optical gain. The numerical results show a non monotonic increase in the threshold current density and a red shift in the lasing wavelength on increasing the stack number, which agrees well with reported experimental results. This observation may partly be attributed to an increase of inhomogeneity in the active region.

Patients with congenital atrial septal defects: effect of age at repair and defect size on pulmonary artery pressures prior to repair.

BACKGROUND: Pulmonary arterial hypertension (PAH) is a major complication of atrial septal defect (ASD) and can be responsible for significant functional limitations and early mortality. Various factors have been shown to predispose ASD patients to the development of PAH. Our study aimed to determine the association between the size of the ASD, the age of the patient and the increase in pulmonary artery pressures. METHODS: Data from 74 ASD patients was retrospectively reviewed, including the patients' presenting symptoms, vital parameters, comorbidities, as well as their preoperative diagnostic workup. Echocardiography findings were used to determine the type and size of the ASD, and pulmonary artery pressures were evaluated using tricuspid regurgitation velocity as assessed by echocardiography or based on cardiac catheterization data. All patients underwent ASD repair either surgically or via percutaneous repair. Univariate and multivariate linear regression was performed to analyze the effect of age and defect size on pulmonary artery pressures. Model adequacy check was also done for the final model. Postoperative morbidity/mortality was additionally evaluated. RESULTS: The study sample comprised 44.6% males and 55.4% females. The most prominent presenting features were shortness of breath (70.3%), chest pain (43.2%), and palpitations (33.8%), and arterial hypertension was the commonest morbidity. Using multiple linear regression analysis, age and size of ASD were found to be independently associated with pulmonary artery pressure. We found that for every 1 mm increase in the size of the ASD, pulmonary artery systolic pressure (PASP) increased by 0.32 mmHg ( P ≤ 0.05). Similarly, with every increase of one year in age, pulmonary artery pressure increased by 0.24 mmHg (P ≤ 0.02). No significant postoperative complications were reported following both types of repair. CONCLUSIONS: Our study concludes that ASD patients are at greater risk of developing PAH with increasing age and increasing ASD size. This can potentially help to determine which ASD patients are at greater risk and require urgent repair of their defects. The study also shows that early repair is best to prevent complications.