dEarly-bactericidal-activity (EBA) studies measure the change in mycobacterial load in sputum over time to evaluate antituberculosis drugs. We investigated whether a delay in sputum processing influences the quantitative results of sputum mycobacterial culture. We identified pretreatment smear-positive sputum samples collected overnight and processed at a single laboratory. Sputum volume, time from sputum collection to processing, CFU counts/ml of sputum, and time to culture positivity (TTP) data were retrieved. We obtained 817 TTP and 794 CFU results from a total of 844 sputum samples. Contamination did not occur more frequently with prolonged storage (TTP, 2.0%; CFU, 2.4%). Sample volumes were <5 ml in 5%, 5 to 10 ml in 46%, and >10 ml in 49%. Delays to processing were 0, 1, 2, and 3 days in 696 (43.2%), 722 (44.8%), 128 (7.9%), and 65 (4.0%) samples, respectively. TTP and CFU did not significantly differ between days of delay to processing (P ‫؍‬ 0.098 and P ‫؍‬ 0.908, respectively), but there was a nonsignificant trend toward a prolonged TTP over time (P ‫؍‬ 0.052, Jonckheere-Terpstra trend test). Sputa of <5 ml in volume showed a significantly prolonged TTP compared to sputum of >5 ml (113 h versus 99 h; P < 0.01) but no significant decrease in CFU. Sputum can be stored under refrigerated conditions for deferred processing for at least 3 days. This means that central laboratories can be used for quantitative mycobacterial study endpoints when delays to processing are not expected to exceed a few days. Care should be taken to collect sputum of sufficient volume. Sputum culture for Mycobacterium tuberculosis remains a cornerstone of clinical mycobacteriology. The detection of viable M. tuberculosis in sputum establishes the diagnosis of pulmonary tuberculosis (TB), and sustained sputum culture conversion is a marker of clinical improvement and cure. Storage of sputum for deferred culture may be considered where decentralized health care centers rely on a central laboratory service, but this may result in loss of viability and false-negative cultures (1-4) or overgrowth of contaminants, particularly if sensitive liquid media are used (5-7). Beyond its clinical purpose, sputum culture can quantify the viable M. tuberculosis sputum load expressed as CFU per ml of sputum counted on agar plates or as times to culture positivity (TTP) of a volume of decontaminated sputum inoculated in liquid mycobacterial culture (8). High sputum mycobacterial loads at diagnosis have been associated with treatment failure and recurrence (9, 10). Early-bactericidal-activity (EBA) studies are considered a key step in the clinical evaluation of individual antituberculosis agents and new combination regimens and describe the change in log CFU and TTP on consecutive sputum samples collected over up to 14 treatment days (2, 11).EBA studies commonly include small groups of sputum smear-positive, treatment-naïve patients who are given investigational treatments under controlled conditions in hospital. The change of the bacterial sputum loa...

The various failure mechanisms in bidirectional glass/epoxy laminates loaded in tension are identified using acoustic emission (AE) analysis. AE data recorded during the tensile testing of a single layer specimen are used to identify matrix cracking and fiber failure, while delamination signals are characterized using a two-layer specimen with a pre-induced defect. Parametric studies using AE count rate and cumulative counts allowed damage discrimination at different levels of loading and Fuzzy C-means clustering associated with principal component analysis were used to discriminate between failure mechanisms. The two above methods led to AE waveform selection: On selected waveforms, Fast Fourier Transform (FFT) enabled calculating the frequency content of each damage mechanism. Continuous wavelet transform allowed identifying frequency range and time history for failure modes, whilst noise content associated with the different failure modes was calculated and removed by discrete wavelet transform. Short Time FFT finally highlighted the possible failure mechanism associated with each signal.

In order to better understand the end of life scenario potential of poly(lactic acid) (PLA) packaging to reduce waste through composting when properly disposed, this study aimed to determine the rate at which 473 mL (16 oz) PLA bottles with and without associated high density polyethylene (HDPE) caps and polypropylene (PP) labels decomposed in an industrial compost pile. Temperature, moisture content, and pH levels of the compost pile were recorded throughout the study to determine their effects on the rate of decomposition and to ensure optimal conditions were met. Analyses performed at weeks 2, 4, and 8 showed that from week 2, a 94 % reduction of mass and weight average molecular weight occurred, along with a complete loss of structural integrity. PLA bottles without caps and labels were considered to be decomposed completely by week 4, while the bottles with the HDPE caps and PP labels showed plastic residues until week 8. The caps and labels acted as a barrier that slowed the rate of biodegradation. This study showed that PLA bottles can be composted in industrial composting facilities in 30–45 days, and it is recommended to remove all caps and labels. The results further indicated that if a proper infrastructure is put in place to allow large scale composting of PLA, this packaging polymer could have a significant impact on reducing municipal solid waste.

No abstract

A field investigation was conducted with four intelligent compaction/continuous compaction control rollers to characterize the spatial reporting of vibratory roller-measured soil properties and to investigate global positioning system (GPS)-based position reporting error. The key reporting characteristics examined include the spatial resolution of roller measurement values (MVs) and the volume/area reflected in each MV. Each vibration-based roller MV investigated is a reflection of soil properties over spatial dimensions that vary across manufacturers. The reporting resolution of roller MVs also varied across manufacturers. Three sources of GPS-determined position error were observed, namely, (1) accuracy of GPS, (2) unaccounted for physical offset of roller-mounted GPS receiver from the drum center, and (3) the spatial averaging of vibration data during roller MV calculation coupled with possible computational latency. The physical offset error was found to be as great as 1.0–2.0 m, while the error due to spatial averaging of vibration data coupled with latency ranged from 0.4 to 0.8 m. Both of these errors are significant but can be estimated and corrected by using a validation procedure described in the paper. Left uncorrected, these errors have a significant adverse effect on the analysis and interpretation of roller MV data when used in quality control/quality assurance specifications.