Displaying publications 21 - 40 of 106 in total

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  1. Estimation of aerosol optical depth at different wavelengths by multiple regression method
    Tan F, Lim HS, Abdullah K, Holben B
    Environ Sci Pollut Res Int, 2016 Feb;23(3):2735-48.
    PMID: 26438373 DOI: 10.1007/s11356-015-5506-3
    This study aims to investigate and establish a suitable model that can help to estimate aerosol optical depth (AOD) in order to monitor aerosol variations especially during non-retrieval time. The relationship between actual ground measurements (such as air pollution index, visibility, relative humidity, temperature, and pressure) and AOD obtained with a CIMEL sun photometer was determined through a series of statistical procedures to produce an AOD prediction model with reasonable accuracy. The AOD prediction model calibrated for each wavelength has a set of coefficients. The model was validated using a set of statistical tests. The validated model was then employed to calculate AOD at different wavelengths. The results show that the proposed model successfully predicted AOD at each studied wavelength ranging from 340 nm to 1020 nm. To illustrate the application of the model, the aerosol size determined using measure AOD data for Penang was compared with that determined using the model. This was done by examining the curvature in the ln [AOD]-ln [wavelength] plot. Consistency was obtained when it was concluded that Penang was dominated by fine mode aerosol in 2012 and 2013 using both measured and predicted AOD data. These results indicate that the proposed AOD prediction model using routine measurements as input is a promising tool for the regular monitoring of aerosol variation during non-retrieval time.
    Matched MeSH terms: Aerosols/chemistry
  2. Fulltext Detection of SARS-CoV-2 in bioaerosols and surface samples from healthcare facilities in Klang Valley, Malaysia
    Robat RM, Nazakat R, Rashid SA, Ismail R, Hasni NAK, Mohamad N, et al.
    Sci Rep, 2025 Feb 28;15(1):7192.
    PMID: 40021779 DOI: 10.1038/s41598-025-91566-z
    The Coronavirus disease 2019 (COVID-19) pandemic has caused significant global threats, as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is primarily transmitted through airborne droplets and bioaerosols. Healthcare workers are particularly at high risk, yet there is limited research on the presence of SARS-CoV-2 in bioaerosols within healthcare facilities in Malaysia. This study aimed to determine the presence and viability of SARS-CoV-2 and its variants of concern in the air and ventilation systems of designated COVID-19 facilities from December 2021 to February 2022. Samples were collected from two hospitals and one quarantine centre (QC), including medical wards, intensive care units, emergency departments, and QC halls. Air samples were obtained using air samplers, while surface samples were taken from return air grilles. SARS-CoV-2 ribonucleic acid (RNA) and its variants were detected using reverse transcription droplet digital polymerase chain reaction (RT-ddPCR) and PCR-based genotyping, respectively. Results showed that Hospital A had a higher rate (24.6%) of positive samples than Hospital B (8.8%). Surface samples had a higher positivity rate (50.0%) compared to air samples (8.3%). The detected variants included delta (34.7%), a mixture of delta and omicron (8.7%), non-variant of concern (non-VOC) (8.7%), and omicron (4.3%). This study emphasizes the need for strict airborne infection control measures for healthcare workers.
    Matched MeSH terms: Aerosols/analysis
  3. Fulltext Thermal Resistance Variations of Fly Ash Geopolymers: Foaming Responses
    Cheng-Yong H, Yun-Ming L, Abdullah MM, Hussin K
    Sci Rep, 2017 03 27;7:45355.
    PMID: 28345643 DOI: 10.1038/srep45355
    This paper presents a comparative study of the characteristic of unfoamed and foamed geopolymers after exposure to elevated temperatures (200-800 °C). Unfoamed geopolymers were produced with Class F fly ash and sodium hydroxide and liquid sodium silicate. Porous geopolymers were prepared by foaming with hydrogen peroxide. Unfoamed geopolymers possessed excellent strength of 44.2 MPa and degraded 34% to 15 MPa in foamed geopolymers. The strength of unfoamed geopolymers decreased to 5 MPa with increasing temperature up to 800 °C. Foamed geopolymers behaved differently whereby they deteriorated to 3 MPa at 400 °C and increased up to 11 MPa at 800 °C. Even so, the geopolymers could withstand high temperature without any disintegration and spalling up to 800 °C. The formation of crystalline phases at higher temperature was observed deteriorating the strength of unfoamed geopolymers but enhance the strength of foamed geopolymers. In comparison, foamed geopolymer had better thermal resistance than unfoamed geopolymers as pores provide rooms to counteract the internal damage.
    Matched MeSH terms: Aerosols
  4. Fulltext Gas sensors based on one dimensional nanostructured metal-oxides: a review
    Arafat MM, Dinan B, Akbar SA, Haseeb AS
    Sensors (Basel), 2012;12(6):7207-58.
    PMID: 22969344 DOI: 10.3390/s120607207
    Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO(2), TiO(2), In(2)O(3), WO(x), AgVO(3), CdO, MoO(3), CuO, TeO(2) and Fe(2)O(3). Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research.
    Matched MeSH terms: Aerosols
  5. Fulltext Evaluation of Melaleuca cajuputi (Family: Myrtaceae) Essential Oil in Aerosol Spray Cans against Dengue Vectors in Low Cost Housing Flats
    Abu Bakar A, Sulaiman S, Omar B, Mat Ali R
    J Arthropod Borne Dis, 2012;6(1):28-35.
    PMID: 23293776
    Melaleuca cajuputi essential oil in aerosol spray was evaluated against the dengue vectors Aedes aegypti and Ae. albopictus at low cost housing flats in Section 10, Setapak, Kuala Lumpur, Malaysia.
    Matched MeSH terms: Aerosols
  6. Heavy metals (Cr, Pb, Cd, Ni) in aerosols emitted from electronic cigarettes sold in Malaysia
    Ting CY, Ahmad Sabri NA, Tiong LL, Zailani H, Wong LP, Agha Mohammadi N, et al.
    J Environ Sci Health A Tox Hazard Subst Environ Eng, 2020;55(1):55-62.
    PMID: 31530230 DOI: 10.1080/10934529.2019.1665950
    While past studies have detected heavy metals in aerosols emitted from electronic cigarettes (ECIG), they have provided little information detailing the practical implications of the findings to the Malaysian population due to variations between products. The aims of this study were to analyse heavy metals of interest (HMOI) in the aerosols emitted from selected ECIG and to evaluate potential health risks by referring to the permissible daily exposure (PDE) from inhalational medications defined by the United States Pharmacopeia Chapter 232. All four HMOI were detected in aerosols emitted from the selected ECIG in Sarawak. Among the four, Cr was present at the highest median levels (6.86 ng/m3), followed by Ni (0.30 ng/m3), Pb (0.19 ng/m3) and Cd (0.01 ng/m3). Five out of 100 combinations (5%) of ECIG and ECIG liquids were found to emit Cr that exceed the recommended PDE. Future studies examining more heavy metal variants, using a larger sample size and different analytical techniques to compare various ECIGs are recommended.
    Matched MeSH terms: Aerosols/analysis; Aerosols/chemistry*
  7. Fulltext Particulate matter (PM2.5) as a potential SARS-CoV-2 carrier
    Nor NSM, Yip CW, Ibrahim N, Jaafar MH, Rashid ZZ, Mustafa N, et al.
    Sci Rep, 2021 01 28;11(1):2508.
    PMID: 33510270 DOI: 10.1038/s41598-021-81935-9
    The rapid spread of the SARS-CoV-2 in the COVID-19 pandemic had raised questions on the route of transmission of this disease. Initial understanding was that transmission originated from respiratory droplets from an infected host to a susceptible host. However, indirect contact transmission of viable virus by fomites and through aerosols has also been suggested. Herein, we report the involvement of fine indoor air particulates with a diameter of ≤ 2.5 µm (PM2.5) as the virus's transport agent. PM2.5 was collected over four weeks during 48-h measurement intervals in four separate hospital wards containing different infected clusters in a teaching hospital in Kuala Lumpur, Malaysia. Our results indicated the highest SARS-CoV-2 RNA on PM2.5 in the ward with number of occupants. We suggest a link between the virus-laden PM2.5 and the ward's design. Patients' symptoms and numbers influence the number of airborne SARS-CoV-2 RNA with PM2.5 in an enclosed environment.
    Matched MeSH terms: Aerosols/analysis; Aerosols/chemistry
  8. Fulltext Application of remote sensing instruments in air quality monitoring in Malaysia
    Mohd Muzammil Salahuddin, Zulfa Hanan Ashaari
    The Pertanika Journal of Scholarly Research Reviews, 2017;3(1):93-112.
    MyJurnal
    The use of remote sensing in detecting aerosol or air pollution is not widely applied in Malaysia. The large area of coverage provided by remote sensing satellite may well be the solution to the lack of spatial coverage by the local ground air quality monitoring stations. This article discusses the application of remote sensing instruments in air quality monitoring of Malaysia. The remote sensing data is validated using ground truths either from local ground air monitoring stations or the Aerosol Robotic Network (AERONET). The correlation between remote sensing is relatively good with R from 0.5 to 0.9 depending on the satellite used. The correlation is much improved using the mixed effects algorithm applied on MODIS Aerosol Optical Depth (AOD) data. Accuracy of predicted air quality data by remote sensing is generally tested using the Root Mean Squared Error (RMSE) against the ground truths data. Besides the Geographic Information System (GIS) tools are used in manipulating the data from both remote sensing and ground stations so as to produce meaningful results such as spatio-temporal pattern mapping of air pollution. Overall the results showed that the application of remote sensing instruments in air quality monitoring in Malaysia is very useful and can be improved further.
    Matched MeSH terms: Aerosols
  9. Fulltext Fine Particle Emissions From Tropical Peat Fires Decrease Rapidly With Time Since Ignition
    Roulston C, Paton-Walsh C, Smith TEL, Guérette ÉA, Evers S, Yule CM, et al.
    J Geophys Res Atmos, 2018 May 27;123(10):5607-5617.
    PMID: 30167349 DOI: 10.1029/2017JD027827
    Southeast Asia experiences frequent fires in fuel-rich tropical peatlands, leading to extreme episodes of regional haze with high concentrations of fine particulate matter (PM2.5) impacting human health. In a study published recently, the first field measurements of PM2.5 emission factors for tropical peat fires showed larger emissions than from other fuel types. Here we report even higher PM2.5 emission factors, measured at newly ignited peat fires in Malaysia, suggesting that current estimates of fine particulate emissions from peat fires may be underestimated by a factor of 3 or more. In addition, we use both field and laboratory measurements of burning peat to provide the first mechanistic explanation for the high variability in PM2.5 emission factors, demonstrating that buildup of a surface ash layer causes the emissions of PM2.5 to decrease as the peat fire progresses. This finding implies that peat fires are more hazardous (in terms of aerosol emissions) when first ignited than when still burning many days later. Varying emission factors for PM2.5 also have implications for our ability to correctly model the climate and air quality impacts downwind of the peat fires. For modelers able to implement a time-varying emission factor, we recommend an emission factor for PM2.5 from newly ignited tropical peat fires of 58 g of PM2.5 per kilogram of dry fuel consumed (g/kg), reducing exponentially at a rate of 9%/day. If the age of the fire is unknown or only a single value may be used, we recommend an average value of 24 g/kg.
    Matched MeSH terms: Aerosols
  10. Pm2.5 and associated ionic species in a sub-urban coastal area of Kuala Terengganu, Southern South China Sea (Malaysia)
    Norhayati Mohd Tahir, Meikee Koh, Suhaimi Suratman
    Sains Malaysiana, 2013;42:1065-1072.
    PM2.5 mass concentration and associated water-soluble ionic species in a sub-urban coastal area of Kuala Terengganu, Malaysia were investigated intermittently from year 2006 to 2009. A total of 78 weekly PM2.5 samples were analyzed. The mass concentration of PM2.5 exhibited annual, seasonal and diurnal variations. Temporal distributions of rainfall, sporadic haze episodes and local air flow (sea breeze circulation) were factors controlling PM2.5 mass variations in the study area. Although the PM2.5 concentrations were increased during haze episodes in 2006 (August and October) and2007 (October), their concentrations however, were still within the international guidelines. The average concentration of individual ions was in decreasing trend; SO42-> NH4+> K+> Na+> NO3-> Cl-> Ca2+. The concentrations of SO42- and NH4+ accounted for > 70% of the water-soluble aerosol mass. More than 80% of ionic species associated with PM2.5 are from non-marine sources. Major processes affecting the ionic composition of PM2.5 are biomass burning, crustal loading and sea spray. Air quality mitigation strategies should focus on anthropogenic activities emitting SO2, which promotes aerosol SO42- formation.
    Matched MeSH terms: Aerosols
  11. Fabrication and Characterization of SnO-Cu₂O Mixed Metal Oxide Thin Films for Photoelectrochemical Applications
    Ahmed S, Shahid MM, Bakar SA, Arshed N, Basirun WJ, Fouad H
    J Nanosci Nanotechnol, 2020 12 01;20(12):7705-7709.
    PMID: 32711646 DOI: 10.1166/jnn.2020.18570
    Herein, we report the synthesis of SnO, Cu₂O and SnO-Cu₂O mixed oxide thin films on fluorinedoped tin oxide (FTO) substrate by Aerosol-Assisted Chemical Vapour Deposition (AACVD) process using [Cu (dmae)₂(H₂O)] and [Sn (dmae) (OAc)]₂ as molecular precursors for SnO and Cu₂O, respectively at 400 °C. The X-ray diffraction (XRD) pattern can be ascribed to the tetragonal phase of SnO crystals with space group P4 and cubic phase of Cu₂O crystals with space group Pn- 3m/nmm, respectively. The surface morphology characteristics of SnO, Cu₂O and SnO-Cu₂Omixed oxide have been investigated using Field Emission Scanning Electron Microscope (FESEM) which revealed that the SnO was grown homogeneously in cubical shape while Cu₂O possess nano balls shaped morphologies. The UV band gap values of SnO-Cu₂O mixed oxide thin film was found to be 2.6 eV appropriate for photoelectrochemical (PEC) applications. The synthesized material was proposed for PEC applications and has shown enhanced catalytic performance in the presence of light.
    Matched MeSH terms: Aerosols
  12. Nanostructure-assisted charge transfer in α-Fe2O3/g-C3N4 heterojunctions for efficient and highly stable photoelectrochemical water splitting
    Arzaee NA, Mohamad Noh MF, Mohd Ita NSH, Mohamed NA, Mohd Nasir SNF, Nawas Mumthas IN, et al.
    Dalton Trans, 2020 Aug 28;49(32):11317-11328.
    PMID: 32760991 DOI: 10.1039/d0dt00683a
    The development of semiconductor heterojunctions is a promising and yet challenging strategy to boost the performance in photoelectrochemical (PEC) water splitting. This paper describes the fabrication of a heterojunction photoanode by coupling α-Fe2O3 and g-C3N4via aerosol-assisted chemical vapour deposition (AACVD) followed by spin coating and air annealing. Enhanced PEC performance and stability are observed for the α-Fe2O3/g-C3N4 heterojunction photoanode in comparison to pristine α-Fe2O3 and the reason is systematically discussed in this paper. Most importantly, the fabricated α-Fe2O3/g-C3N4 film shows impressive stability, retaining more than 90% of the initial current over 12 h operating time. The excellent stability of the heterojunction photoanode is achieved due to the unique nanoflake structure of α-Fe2O3 induced by AACVD. This nanostructure promotes good adhesion with the g-C3N4 particles, as the particles tend to be trapped within the α-Fe2O3 valleys and eventually create strong and large interfacial contacts. This leads to improved separation of charge carriers at the α-Fe2O3/g-C3N4 interface and suppression of charge recombination in the photoanode, which are confirmed by the transient decay time, charge transfer efficiency and electrochemical impedance analysis. Our findings demonstrate the importance of nanostructure engineering for developing heterojunction structures with efficient charge transfer dynamics.
    Matched MeSH terms: Aerosols
  13. Rapid fabrication of oxygen defective α-Fe2O3(110) for enhanced photoelectrochemical activities
    Mohamad Noh MF, Ullah H, Arzaee NA, Ab Halim A, Abdul Rahim MAF, Mohamed NA, et al.
    Dalton Trans, 2020 Sep 14;49(34):12037-12048.
    PMID: 32869793 DOI: 10.1039/d0dt00406e
    Defect engineering is increasingly recognized as a viable strategy for boosting the performance of photoelectrochemical (PEC) water splitting using metal oxide-based photoelectrodes. However, previously developed methods for generating point defects associated with oxygen vacancies are rather time-consuming. Herein, high density oxygen deficient α-Fe2O3 with the dominant (110) crystal plane is developed in a very short timescale of 10 minutes by employing aerosol-assisted chemical vapor deposition and pure nitrogen as a gas carrier. The oxygen-defective film exhibits almost 8 times higher photocurrent density compared to a hematite photoanode with a low concentration of oxygen vacancies which is prepared in purified air. The existence of oxygen vacancies improves light absorption ability, accelerates charge transport in the bulk of films, and promotes charge separation at the electrolyte/semiconductor interface. DFT simulations verify that oxygen-defective hematite has a narrow bandgap, electron-hole trapped centre, and strong adsorption energy of water molecules compared to pristine hematite. This strategy might bring PEC technology another step further towards large-scale fabrication for future commercialization.
    Matched MeSH terms: Aerosols
  14. Fulltext Exposure to microbial contaminants in Metalworking fluids (MWF) and the fractional exhaled nitric oxide (FeNO) levels among machining industry workers
    Nurul Maizura Hashim, Zailina Hashim, Rukman Awang Hamat, Hayati Kadir
    Malaysian Journal of Medicine and Health Sciences, 2019;15(204):147-152.
    MyJurnal
    Introduction: Water based Metalworking fluids (MWF) are commonly used in machining industries and are excellent media for microorganism growth. The study aimed at determining the relationship between the airway inflammation as indicated by fractional exhaled nitric oxide (FeNO) with the microbial contaminants of MWF in aerosol and bulk sample as well as the workers’ reported respiratory health symptoms. Methods: This cross sectional study was carried out on 138 machining workers. Their FeNO were measured using NIOX-MINO instrumentation. The microbial as- sessments of bacteria and fungus were carried out on the MWF bulk samples and the aerosol using a sampler DUO SAS SUPER 360TM. Results: Findings showed significant difference in the FeNO levels in workers from various job sections (p=0.01). Significant relationships found between high FeNO levels with their closeness to the machines (p=0.03), high number of machines in the workplaces (p=0.02), high environmental bacteria colonies (p=0.04), lon- ger employment years (p
    Matched MeSH terms: Aerosols
  15. Graphene-mediated microfluidic transport and nebulization via high frequency Rayleigh wave substrate excitation
    Ang KM, Yeo LY, Hung YM, Tan MK
    Lab Chip, 2016 09 21;16(18):3503-14.
    PMID: 27502324 DOI: 10.1039/c6lc00780e
    The deposition of a thin graphene film atop a chip scale piezoelectric substrate on which surface acoustic waves are excited is observed to enhance its performance for fluid transport and manipulation considerably, which can be exploited to achieve further efficiency gains in these devices. Such gains can then enable complete integration and miniaturization for true portability for a variety of microfluidic applications across drug delivery, biosensing and point-of-care diagnostics, among others, where field-use, point-of-collection or point-of-care functionality is desired. In addition to a first demonstration of vibration-induced molecular transport in graphene films, we show that the coupling of the surface acoustic wave gives rise to antisymmetric Lamb waves in the film which enhance molecular diffusion and hence the flow through the interstitial layers that make up the film. Above a critical input power, the strong substrate vibration displacement can also force the molecules out of the graphene film to form a thin fluid layer, which subsequently destabilizes and breaks up to form a mist of micron dimension aerosol droplets. We provide physical insight into this coupling through a simple numerical model, verified through experiments, and show several-fold improvement in the rate of fluid transport through the film, and up to 55% enhancement in the rate of fluid atomization from the film using this simple method.
    Matched MeSH terms: Aerosols
  16. Responses of Anopheles balabacensis balabacensis baisas to ultra-low-volume aerosols of sumithion in Sabah, Malaysia
    Hii JL
    J Commun Dis, 1980 Mar;12(1):14-22.
    PMID: 7451931
    Matched MeSH terms: Aerosols
  17. Indoor thermal fogging against vector mosquitoes with two Bacillus thuringiensis israelensis formulations, Vectobac ABG 6511 water-dispersible granules and Vectobac 12AS liquid
    Yap HH, Lee YW, Zairi J
    J Am Mosq Control Assoc, 2002 Mar;18(1):52-6.
    PMID: 11998931
    Bioefficacy of thermal fogging application of 2 Bacillus thuringiensis israelensis formulations, Vectobac ABG 6511 water-dispersible granules (3,000 international toxic unit [ITU]/mg) and Vectobac 12AS liquid (1,200 ITU/mg), was assessed for larvicidal activities against Aedes aegypti, Aedes albopictus, Anopheles dirus, and Culex quinquefasciatus. Portable Agrofog AF35 sprayers were used to apply the 2 formulations indoors in residential premises on Penang Island, Malaysia. Vectobac ABG 6511 showed good larvicidal effect against all 4 mosquito species at 3 of the higher doses tested (2.91 x 10(9), 1.45 x 10(9), and 0.71 x 10(9) ITU/ha), with more than 96% mortality at 48 h after spraying. As a comparative formulation, Vectobac 12AS also showed good larvicidal activity against all 4 mosquito species at 2 of the higher doses tested (2.87 x 10(9) and 1.46 x 10(9) ITU/ha), with more than 92.5% mortality at 48 h after spraying. Larvae of An. dirus were significantly more susceptible to both water-based Vectobac formulations when compared to the other 3 mosquito species. Both microbial formulations showed better efficacy at higher doses. However, even at the lowest dose tested, Vectobac ABG 6511 and Vectobac 12AS (both at 0.36 x 10(9) ITU/ha) showed larvicidal properties, with more than 66% mortality at 48 h after spraying. Overall, for this bacterial agent, the water-dispersible granule formulation has better prospects than the liquid formulation for the control of larvae of vector mosquitoes.
    Matched MeSH terms: Aerosols
  18. Plasma-sprayed coating of hydroxyapatite on metal implants--a review
    Talib RJ, Toff MR
    Med J Malaysia, 2004 May;59 Suppl B:153-4.
    PMID: 15468864
    Metal implants such as titanium, stainless steel and Co-Cr-Mo are used for load bearing purposes such as hip joint prostheses, fixing plates and dental root implants. For practical application, plasma-sprayed coatings of hydroxyapatite (HA) on metal implants are applied to promote early formation of strong bonds between metal implant and living bone. Plasma spray coating involves heating of HA material to a semi-molten or molten state and then propels its to a metal substrate. The plasma flame temperature is in the range of 6,000 degrees C to 16,000 degrees C but the surface temperature of the substrate rarely exceeds 150 degrees C. The HA materials are feed into the spray gun in the form of powders. Furthermore, this paper will discuss the processes of plasma-sprayed coating of HA on various types of metal implants.
    Matched MeSH terms: Aerosols
  19. Effect of storage temperature on the stability of spray dried bacteriophage powders
    Leung SSY, Parumasivam T, Nguyen A, Gengenbach T, Carter EA, Carrigy NB, et al.
    Eur J Pharm Biopharm, 2018 Jun;127:213-222.
    PMID: 29486303 DOI: 10.1016/j.ejpb.2018.02.033
    This study aimed to assess the robustness of using a spray drying approach and formulation design in producing inhalable phage powders. Two types of Pseudomonas phages, PEV2 (Podovirus) and PEV40 (Myovirus) in two formulations containing different amounts of trehalose (70% and 60%) and leucine (30% and 40%) were studied. Most of the surface of the produced powders was found to be covered in crystalline leucine. The powders were stored at 4 °C and 20 °C under vacuum. The phage stability and in vitro aerosol performance of the phage powders were examined on the day of production and after 1, 3 and 12 months of storage. A minor titer loss during production was observed for both phages (0.2-0.8 log10 pfu/ml). The storage stability of the produced phage powders was found to be phage and formulation dependent. No further reduction in titer occurred for PEV2 powders stored at 4 °C across the study. The formulation containing 30% leucine maintained the viability of PEV2 at 20 °C, while the formulation containing 40% leucine gradually lost titer over time with a storage reduction of ∼0.9 log10 pfu/ml measured after 12 months. In comparison, the PEV40 phage powders generally had a ∼ 0.5 log10 pfu/ml loss upon storage regardless of temperature. When aerosolized, the total in vitro lung doses of PEV2 were of the order of 107 pfu, except the formulation containing 40% leucine stored at 20 °C which had a lower lung dose. The PEV40 powders also had lung doses of 106-107 pfu. The results demonstrate that spray dried Myoviridae and Podoviridae phage in a simple formulation of leucine and trehalose can be successfully stored for one year at 4 °C and 20 °C with vacuum packaging.
    Matched MeSH terms: Aerosols/chemistry
  20. Fulltext Experimental Infection of Syrian Hamsters With Aerosolized Nipah Virus
    Escaffre O, Hill T, Ikegami T, Juelich TL, Smith JK, Zhang L, et al.
    J Infect Dis, 2018 10 05;218(10):1602-1610.
    PMID: 29912426 DOI: 10.1093/infdis/jiy357
    Background: Nipah virus (NiV) is a paramyxovirus (genus Henipavirus) that can cause severe respiratory illness and encephalitis in humans. Transmission occurs through consumption of NiV-contaminated foods, and contact with NiV-infected animals or human body fluids. However, it is unclear whether aerosols derived from aforesaid sources or others also contribute to transmission, and current knowledge on NiV-induced pathogenicity after small-particle aerosol exposure is still limited.

    Methods: Infectivity, pathogenicity, and real-time dissemination of aerosolized NiV in Syrian hamsters was evaluated using NiV-Malaysia (NiV-M) and/or its recombinant expressing firefly luciferase (rNiV-FlucNP).

    Results: Both viruses had an equivalent pathogenicity in hamsters, which developed respiratory and neurological symptoms of disease, similar to using intranasal route, with no direct correlations to the dose. We showed that virus replication was predominantly initiated in the lower respiratory tract and, although delayed, also intensely in the oronasal cavity and possibly the brain, with gradual increase of signal in these regions until at least day 5-6 postinfection.

    Conclusion: Hamsters infected with small-particle aerosolized NiV undergo similar clinical manifestations of the disease as previously described using liquid inoculum, and exhibit histopathological lesions consistent with NiV patient reports. NiV droplets could therefore play a role in transmission by close contact.

    Matched MeSH terms: Aerosols/administration & dosage*
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