In this study MD simulation methodology was used to simulate hLTA4H enzyme complexed with its two diverse substrates along with mutated key residues. The aim of this study was to investigate the structural and conformational changes in the bi-functional active site of the enzyme reflecting on the catalytic activity. This was considered very important and necessary to script the reasons for the observed loss of activity due to particular mutations as the solved X-ray structures failed to show the structural changes. Eight systems including two WT, enzyme-LTA4 and enzyme-RAR complexes along with three independent mutations (E271Q, R563A, and K565A) in each complex were simulated in this study. The observed hydrogen bond interaction network and distance between the catalytically important atoms have correlated well with the experimental results. The E271 residue which is considered very important for both functions of the enzyme and E271Q systems have revealed from our study that this residue acts as a hook to hold the catalytic metal ion at its location and also plays a role of N-terminal recognition point for the aminopeptidase function. Both the E271Q systems have lost the expected binding mode of the substrates for the successful catalysis. The other mutant R563A and K565A systems have also revealed the structural changes and binding mode differences explaining the loss of activity in mutant systems. In L-LTA4 systems, the substrate binding mode in R563A system has changed completely that the long alkyl chain of LTA4 was completely buried into the hydrophobic pocket. This difference in binding mode of LTA4 was completely because of the loss of hydrogen bond interaction with R563 residue. In terms of L-RAR systems, the same mutation R563A has affected the binding mode of RAR and N-terminal recognition through E271 residue in peptide binding. Because of this missing N-terminal recognition the catalytic distance between the metal ion and the carbonyl group of the N-terminal peptide bond was high in this system. The K565A systems in both the substrate complexes have shown different structural changes. In L-LTA4 system the binding mode of the substrate was very much similar to the WT explaining the less importance of K565 in LTA4 binding whereas in L-RAR system the binding mode has lost both the N-terminal and C-terminal recognitions leading to the loss of activity. These results obtained from this study can be effectively used in designing future hLTA4H inhibitors as anti-inflammatory and anti-cancer therapeutics. Table S1 The structural changes which were not seen in experimental studies observed through the MD simulation studies.  Molecular and Microscopic Analysis of Bacteria and Viruses in Exhaled Breath Collected Using a Simple Impaction and Condensing Method Exhaled breath condensate (EBC) is increasingly being used as a non-invasive method for disease diagnosis and environmental exposure assessment. By using hydrophobic surface, ice, and droplet scavenging, a simple impaction and condensing based collection method is reported here. Human subjects were recruited to exhale toward the device for 1, 2, 3, and 4 min. The exhaled breath quickly formed into tiny droplets on the hydrophobic surface, which were subsequently scavenged into a 10 µL rolling deionized water droplet. The collected EBC was further analyzed using culturing, DNA stain, Scanning Electron Microscope (SEM), polymerase chain reaction (PCR) and colorimetry (VITEK 2) for bacteria and viruses. Experimental data revealed that bacteria and viruses in EBC can be rapidly collected using the method developed here, with an observed efficiency of 100 µL EBC within 1 min. Culturing, DNA stain, SEM, and qPCR methods all detected high bacterial concentrations up to 7000 CFU/m(3) in exhaled breath, including both viable and dead cells of various types. Sphingomonas paucimobilis and Kocuria variants were found dominant in EBC samples using VITEK 2 system. SEM images revealed that most bacteria in exhaled breath are detected in the size range of 0.5–1.0 µm, which is able to enable them to remain airborne for a longer time, thus presenting a risk for airborne transmission of potential diseases. Using qPCR, influenza A H3N2 viruses were also detected in one EBC sample. Different from other devices restricted solely to condensation, the developed method can be easily achieved both by impaction and condensation in a laboratory and could impact current practice of EBC collection. Nonetheless, the reported work is a proof-of-concept demonstration, and its performance in non-invasive disease diagnosis such as bacterimia and virus infections needs to be further validated including effects of its influencing matrix. Bioaerosols are present virtually anywhere in the environment, and their exposure is shown to cause numerous adverse health effects [1] [2] . In addition, there is also a possible release of biowarfare agents in a man-made bio-terror event. A number of studies demonstrated that the respiratory tract can be colonized with disease organisms [3] [4] [5] . Through talking, coughing, sneezing or singing, the potential virulent organisms can be exhaled and spread into the ambient environment [6] , which accordingly causes air contamination. For example, SARS in 2003 and H1N1 in 2009 outbreaks were shown to be attributed to the airborne route of disease transmission [7] [8] [9] [10] .