The HIV genotypic resistance test (GRT) is a standard of care for the clinical management of HIV/AIDS patients. In recent decades, population or Sanger sequencing has been the foundation for drug ...resistance monitoring in clinical settings. However, the advent of high-throughput or next-generation sequencing has caused a paradigm shift towards the detection and characterization of low-abundance covert mutations that would otherwise be missed by population sequencing. This is clinically significant, as these mutations can potentially compromise the efficacy of antiretroviral therapy, causing poor virologic suppression. Therefore, it is important to develop a more sensitive method so as to reliably detect clinically actionable drug-resistant mutations (DRMs). Here, we evaluated the diagnostic performance of a laboratory-developed, high-throughput, sequencing-based GRT using 103 archived clinical samples that were previously tested for drug resistance using population sequencing. As expected, high-throughput sequencing found all the DRMs that were detectable by population sequencing. Significantly, 78 additional DRMs were identified only by high-throughput sequencing, which is statistically significant based on McNemar’s test. Overall, our results complement previous studies, supporting the notion that the two methods are well correlated, and the high-throughput sequencing method appears to be an excellent alternative for drug resistance testing in a clinical setting.
Abstract
Mainstream partial nitritation/anammox (PN/A), coupled with excess biological phosphorus removal, in a 200,000 m3/d step-feed activated sludge process (Train 2) in the Changi Water ...Reclamation Plant (WRP), Singapore, has been studied and reported. This paper presents an overview of process performance and the microbial community during the period from 2011 to 2016. The site data showed that, along with the reduction of dissolved oxygen (DO) from 1.7 to 1.0 mg O2/L in the aeration zones, the concentrations of ammonium and nitrate of the final effluent increased, while nitrite decreased, resulting in an increase of 2.4 mg N/L of total inorganic nitrogen. Autotrophic nitrogen removal was higher than heterotrophic biological nitrogen removal under higher DO concentration conditions, but decreased under low DO operating condition. These macro-scale changes were caused by shifts of the nitrogen-converting microbial community. The ammonia oxidizing bacteria (AOB) population abundance was reduced by 30 times, while the nitrite oxidizing bacteria (NOB) population abundance and specific activity increased significantly with a shift of dominant genus from Nitrobacter to Nitrospira. The ratio of AOB and NOB specific activities were reduced from 12.8 to 1.6, and the ex situ nitrite accumulation ratio reduced from 76% to 29%. Changes in the microbial community and overall process performance illustrated that, compared to the excellent NOB suppression under high DO conditions, NOB were more active after the DO concentration reduction despite still being partly suppressed. This case study demonstrated, for the first time, the influence of DO reduction on the nitrogen conversion microbial community and PN/A process performance for a suspended growth system. Its relevance to biofilm and hybrid PN/A processes is also discussed.
Mainstream partial nitritation and Anammox (PN/A) has been observed and studied in the step-feed activated sludge process at the Changi water reclamation plant (WRP), which is the largest WRP ...(800,000 m3/d) in Singapore. This paper presents the study results for enhanced biological phosphorus removal (EBPR) co-existing with PN/A in the activated sludge process. Both the in-situ EBPR efficiency and ex-situ activities of phosphorus release and uptake were high. The phosphorus accumulating organisms were dominant, with little presence of glycogen accumulating organisms in the activated sludge. Chemical oxygen demand (COD) mass balance illustrated that the carbon usage for EBPR was the same as that for heterotrophic denitrification, owing to autotrophic PN/A conversions. This much lower carbon demand for nitrogen removal, compared to conventional biological nitrogen removal, made effective EBPR possible. This paper demonstrated for the first time the effective EBPR co-existence with PN/A in the mainstream in a large full-scale activated sludge process, and the feasibility to accommodate EBPR into the mainstream PN/A process. It also shows EBPR can work under warm climates.
A laboratory fed-batch reactor has been used to study under controlled conditions the performance of partial nitritation/anammox for the 200,000 m(3)/day step-feed activated sludge process at the ...Changi Water Reclamation Plant, Singapore. The similarity of the concentrations of NH(4), NO(2), NO(3), PO(4), suspended chemical oxygen demand (sCOD), pH, and alkalinity (ALK) between the on-site process and laboratory reactor illustrates that the laboratory fed-batch reactor can be used to simulate the site performance. The performance of the reactor fed by primary effluent illustrated the existence of anammox and heterotrophic denitrification and apparent excessive biological phosphorus removal as observed from the site. The performance of the reactor fed by final effluent proved the presence of anammox process on site. Both the laboratory reactor and on-site process showed that higher influent 5-day biochemical oxygen demand/total nitrogen (BOD(5)/TN) (COD/TN) ratio increases the nitrogen removal efficiency of the process.
Mainstream partial nitritation/anammox (PN/A), coupled with excess biological phosphorus removal, in a 200,000 m
/d step-feed activated sludge process (Train 2) in the Changi Water Reclamation Plant ...(WRP), Singapore, has been studied and reported. This paper presents an overview of process performance and the microbial community during the period from 2011 to 2016. The site data showed that, along with the reduction of dissolved oxygen (DO) from 1.7 to 1.0 mg O
/L in the aeration zones, the concentrations of ammonium and nitrate of the final effluent increased, while nitrite decreased, resulting in an increase of 2.4 mg N/L of total inorganic nitrogen. Autotrophic nitrogen removal was higher than heterotrophic biological nitrogen removal under higher DO concentration conditions, but decreased under low DO operating condition. These macro-scale changes were caused by shifts of the nitrogen-converting microbial community. The ammonia oxidizing bacteria (AOB) population abundance was reduced by 30 times, while the nitrite oxidizing bacteria (NOB) population abundance and specific activity increased significantly with a shift of dominant genus from Nitrobacter to Nitrospira. The ratio of AOB and NOB specific activities were reduced from 12.8 to 1.6, and the ex situ nitrite accumulation ratio reduced from 76% to 29%. Changes in the microbial community and overall process performance illustrated that, compared to the excellent NOB suppression under high DO conditions, NOB were more active after the DO concentration reduction despite still being partly suppressed. This case study demonstrated, for the first time, the influence of DO reduction on the nitrogen conversion microbial community and PN/A process performance for a suspended growth system. Its relevance to biofilm and hybrid PN/A processes is also discussed.
Mainstream partial nitritation and Anammox (PN/A) has been observed and studied in the step-feed activated sludge process at the Changi water reclamation plant (WRP), which is the largest WRP ...(800,000 m
/d) in Singapore. This paper presents the study results for enhanced biological phosphorus removal (EBPR) co-existing with PN/A in the activated sludge process. Both the in-situ EBPR efficiency and ex-situ activities of phosphorus release and uptake were high. The phosphorus accumulating organisms were dominant, with little presence of glycogen accumulating organisms in the activated sludge. Chemical oxygen demand (COD) mass balance illustrated that the carbon usage for EBPR was the same as that for heterotrophic denitrification, owing to autotrophic PN/A conversions. This much lower carbon demand for nitrogen removal, compared to conventional biological nitrogen removal, made effective EBPR possible. This paper demonstrated for the first time the effective EBPR co-existence with PN/A in the mainstream in a large full-scale activated sludge process, and the feasibility to accommodate EBPR into the mainstream PN/A process. It also shows EBPR can work under warm climates.
Abstract Thermochromic materials are substances that change color in response to temperature variations. Today, sustainability concerns are the main drivers of thermochromic research, with smart, ...energy‐efficient windows being one of the primary applications. While vanadium oxides and leuco dyes are traditionally the main thermochromic materials, hydrogels operating based on change of solvation have risen as some of the most promising materials due to their high optical transparency and good solar modulating abilities. In this work, a distinct mechanism for thermochromism arising from the crystalline solid to amorphous solid polymer transition, with a corresponding transition from an opaque state to a transparent state is disclosed. Both ultra‐high optical transparency ( T lum up to 99%) and ultra‐high solar modulation (Δ T solar up to 87%) are observed. The transition temperature is tunable from 11 to 61 °C by tuning the polymer structure. When incorporated into applications such as greenhouse materials and thermoelectric devices, significant performance enhancement is observed, due to the thermochromic material functioning as a thermal valve, speeding up solar heat absorbance while inhibiting the cooling process via its phase transition.
We aim to determine the utility of CT scan as a method to accurately confirm pediatric airway foreign bodies (AFBs), the current gold standard of which is chest X-ray as the primary imaging modality ...in the investigation screening of AFBs with progression to microlaryngobronchoscopy.
A retrospective cohort study of children diagnosed with suspected AFBs between July 2019 and June 2020 was conducted. The primary outcome of missed AFBs from radiologic investigations was recorded.
A total of 226 children with an average age of 1.94 years were included in this study. One hundred and two children were eventually admitted to the hospital for microlaryngobronchoscopy. A total of 89 cases were initially examined by chest X-ray with the diagnosis confirmed in 26 cases. The initial examination was chest CT scan in 105 cases, of which the diagnosis was confirmed in 46 cases. The initial examination was chest CT scan with airway reconstruction in 32 cases, and the diagnosis was confirmed in 17 cases. Patients with negative chest CT scan with airway reconstruction were observed to have resolution of symptoms with no further need for bronchoscopy.
Chest CT scan with airway reconstruction had the highest rate of confirmed diagnosis of pediatric AFBs on initial scanning, followed by chest CT scan, and finally chest X-ray with fluoroscopy; there was no missed diagnosis in chest CT scan with airway reconstruction. Chest CT scan with airway reconstruction can accurately and quickly detect AFBs and reduce unnecessary bronchoscopy.
To determine if obesity is associated with poorer patient-reported outcomes (PROs) in patients with axial spondyloarthritis (axSpA), we conducted a cross-sectional study using data of the PRESPOND ...registry from a tertiary referral center in Singapore between 2011 and 2015. Demographics, clinical, and PRO variables were collected. Patients were divided into three categories: normal (BMI < 23 kg/m
2
), overweight (23 kg/m
2
≤ BMI < 27.5 kg/m
2
) and obese (BMI ≥ 27.5 kg/m
2
), using Asian BMI classification. The dependent variables are Pain score, Bath Ankylosing Spondylitis Patient Global Score (BAS-G), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Health Assessment Questionnaire (HAQ), and Medical Outcomes Study Short Form 36 version 2 (SF-36). Multivariate regression analyses were performed with these dependent variables and obesity categories, adjusting for confounders. Among 194 patients with axSpA, 32% are overweight while 22% are obese. We found that obese patients had significant poorer pain (β: 11.87, 95%CI 2.13, 21.60) and BAS-G scores (β: 10.18, 95%CI 1.59, 18.76) when compared to normal BMI patients. However, obesity was not associated with BASDAI (β 0.50, 95%CI -0.22, 1.22), BASFI (β 0.08, 95%CI -0.66, 0.81), HAQ (β -0.07, 95%CI -0.21, 0.06), physical component summary (β -0.02, 95%CI -4.47, 4.44), and mental component summary (β -2.85, 95%CI -7.57, 1.88) of SF-36. Obesity was associated with pain score and BAS-G but not with BASDAI, BASFI, HAQ, and SF-36. Further study is needed to examine the causal relationship between obesity and poorer PROs.