Low Activity Research Articles

Upper and Lower Limb Muscle Activation during Green Care: An Electromyographic Analysis

Green care activities are associated with lower intensity and a lower risk of injury than agricultural activities aimed at producing agricultural and livestock products; however, the risk of health problems cannot be completely ruled out. To implement green care interventions to improve physical health, it is essential to identify the green care activity levels and biomechanical characteristics of the movements that are appropriate for each subject’s physical functions and goals. Thus, this study was conducted to determine the muscle activation of the upper and lower limbs during 19 green care farming activities. We used electromyography signals, which are biomedical signals that measure the action potentials generated in the muscles and nervous system when the muscles contract, to evaluate the muscle activation. Twenty adults (aged 29.9 ± 9.6 years) participated in this study. Participants performed 19 green care farming activities, including horticultural activity, animal-mediated, and off-farming activities. The participants performed each activity three times. The electromyography data were assessed using surface electromyography during activities to measure muscle activation. As a result, 16 upper and lower limb muscles were activated during the green care farming activities, which showed significantly different muscle activation by care farming activity. As a result of the comparison of muscle activity according to each muscle, many of the muscles of the upper and lower limbs were most activated during organizing a garden plot, transplanting plants, and collecting natural objects. In conclusion, the electromyography data obtained during this study suggest that green care farming interventions may be effective for training specific muscles of the upper and lower limbs.

Satellite orbit determination and time synchronization using GPS single-frequency observables in low and high solar activities

We assess the orbit accuracy and time synchronization error using the L1 and C1 observables during the different solar activities. In general, GPS single-frequency (SF) observable can be used for commercial applications in satellite industry. The accuracy of satellite orbit determination using the SF observations is dominated by solar activities. The solar activities are indexed by the F10.7 value. The different solar activities lead to the ionosphere perturbation, triggering off the occurrence probability of ionospheric irregularities. The ionospheric irregularity affects the amplitude and phase of GPS signal. The affected amplitude and phase are indexed by the S4 value. We determine the GRACE satellite orbit using the SF GPS observations and compare the resulting orbit to that derived by dual-frequency observations for the effectiveness. The SF phase data are very sensitive to the variation in electron density and indirectly affects both the orbit accuracy and the time synchronization error. This is most likely caused by the phase ambiguity disturbed by the ionosphere. However, the C1 is relatively free from such a disturbance due to the strong signal-to-noise ratio (SNR) and the phase shift keying technique. The C1 performs the consistent solution over the low and high solar activities. However, this is not the case for the L1. The L1-derived orbit solution during the high solar activities is worse than that during the low solar activities. On the other hand, the time synchronization errors derived by the L1 and C1 are also different. The L1-derived time synchronization error has a relatively large perturbation as compared to the C1-derived one, which shows a consistent solution for a long-term period. This work suggests that the C1 observable is able to produce a consistent the orbit solution and time synchronization for the commercial applications of the satellite industry.Graphical

Occupational burnout and their determinants among schoolteachers in Nepal: a cross-sectional study

BackgroundBurnout syndrome attributable to cumulative stressors is highly prevalent among teachers. Despite this, knowledge of burnout syndrome among schoolteachers in lower-middle-income countries are limited, therefore we aimed to investigate self-reported occupational burnout syndrome and associated factors among schoolteachers in Nepal.MethodsA survey was conducted among randomly selected 37 community schools in Kathmandu, Nepal in 2022, with a total sample of 218 schoolteachers (70% male). Occupational burnout was assessed using the Nepali version of the validated Maslach Burnout Inventory (MBI-ES). MBI-ES consists of 22 items assessing occupational burnout, which were classified into emotional exhaustion (EE, 9 items, score range: 0–45), depersonalization (DP, 5 items, 0–23), and personal accomplishment (PA, 8 items; 3–48). The greater score in EE and DP and the lower score in PA indicate a higher level of burnout. Various socio-demographic, lifestyle, and work-related factors were examined as determinants of occupational burnout using ANOVA and multivariable linear regression models.ResultsThe mean scores of EE, DP, and PA were 14.99 (Standard Deviation, SD = 9.79), 4.18 (SD = 4.57), and 42.11 (SD = 6.82) respectively. Poor/moderate work ability contributed to poorer ratings of all three dimensions. Teaching special needs students contributed to EE and DP, whereas low physical activity and alcohol intake were associated with PA only. Younger age, being married, language of teaching, having a disability, sub-optimal physical fitness, poor sleep quality, and ever smoking contributed to EE only.ConclusionOccupational burnout among schoolteachers was relatively high. Marital status, lifestyle behavioral, and work-related factors were associated especially with EE and workability was a strong determinant of all three dimensions.Clinical trial registration numberNCT05626543.

Assessment of antimicrobial activity of Meliponula ferrugica in pathogenic wound samples

Background: Honey is a naturally occurring sweet material that bees make from nectar from flowers, secretions from plant parts, or excretions from plants that suck insects from plant parts. Honey’s antibacterial and antifungal qualities are widely known, and it has been used to heal burns, surgical wounds, and decubitus ulcers. Honey instantly sterilizes wounds affected by Staphylococcus aureus. The honey’s ability to fight bacteria can be ascertained by the nectar’s origin. Many antibiotic resistances among the bacteria that cause infections in humans have directly evolved as a result of the use of antibiotics in clinical practice. Methods: This study found that Bergey’s manual of determinative bacteriology can be used to identify Pseudomonas aeruginosa and Staphylococcus aureus. According to the study’s findings, honey has a capacity to neutralise Pseudomonas aeruginosa and Staphylococcus aureus that have been isolated from infected wounds. Honey’s antibacterial characteristics account for a significant portion of its antibacterial activity. Results: Staphylococcus aureus and Pseudomonas aeruginosa were both susceptible to the antibacterial activity of the honey sample. Pseudomonas aeruginosa exhibited lower activity compared to Staphylococcus aureus. Conclusions: The results of this investigation show that Bergey’s handbook of determinative bacteriology can be used to identify Staphylococcus aureus and Pseudomonas aeruginosa. According to the study’s findings, honey has the ability to neutralise Pseudomonas aeruginosa and Staphylococcus aureus that have been isolated from infected wounds.

2D equivalent linear ground response analysis for randomized site profiles

AbstractLocal soil conditions play a crucial role in shaping ground surface responses and impacting the intensity of ground shaking. In this study, the influence of different site profiles on computed ground motion was investigated using a 2D equivalent linear analysis approach. Four distinct site profiles: sand, clay, sand-clay-sand-clay, and clay-sand-clay-sand profiles were considered. The results were presented using multiple metrics, including surface acceleration, displacement, modulus decreasing ratio, and coherence analysis. Notably, the clay profile significantly influenced ground motion, while the sand profile exhibited relatively lower seismic activity. This suggests that softer sites significantly influence ground motion, leading to potentially high levels of shaking.

The Photodynamic Antibacterial Activity Properties of a Series of Indium(III) Porphyrins and their Gold and Silver Nanoparticle Conjugates

AbstractIn(III) tetraarylporphyrin complexes with 4‐thiomethylphenyl (1‐InPor), thien‐3‐yl (2‐InPor), thien‐2‐yl (3‐InPor) and 5‐bromothien‐2‐yl (4‐InPor) meso‐aryl rings have been synthesized and characterized. The complexes have been conjugated to gold and silver nanoparticles (AuNPs and AgNPs). The photodynamic antimicrobial chemotherapy (PACT) activities of 1–4‐InPor and their AuNP and AgNP conjugates have been investigated against both planktonic bacteria and biofilms of Gram‐(+) S. aureus and Gram‐(−) E. coli. 2.5 μg.mL−1 solutions of 1–4‐InPor exhibited favorable PACT activities against planktonic S. aureus with high Log10 reduction values in the 4.28–7.69 range upon 75 min photoirradiation with a Thorlabs M625L3 LED (240 mW.cm−2) mounted onto the illumination chamber of a Modulight 7710 medical laser system to provide a dose at the well‐plate of 86 mJ.cm−2.min−1. In contrast, low values in the 1.4–1.9 range were obtained against E. coli with 10 μg.mL−1 solutions. 1–4‐InPor exhibited relatively low PACT activity against the biofilm cells of S. aureus and E. coli. Conjugation of 1–4‐InPor to AgNPs and AuNPs significantly enhanced the PACT activities. This is demonstrated by the complete eradication of planktonic S. aureus at shorter irradiation times with high Log10 values>7.69 and moderate Log10 values>2 against planktonic E. coli for the meso‐thienylporphyrin conjugates.

Efficacy and Safety of Upadacitinib or Elsubrutinib Alone or in Combination for Systemic Lupus Erythematosus: A Phase 2 Randomized Controlled Trial.

The 48-week, phase 2 SLEek study (NCT03978520) evaluated the efficacy and safety of upadacitinib (Janus kinase inhibitor) and elsubrutinib (Bruton's tyrosine kinase inhibitor) alone or in combination (ABBV-599) in adults with moderately to severely active systemic lupus erythematosus (SLE). Patients were randomized 1:1:1:1:1 to once-daily (QD) ABBV-599 high dose (HD; elsubrutinib 60mg + upadacitinib 30mg), ABBV-599 low dose (LD; elsubrutinib 60mg + upadacitinib 15mg), elsubrutinib 60mg, upadacitinib 30mg, or placebo. The primary endpoint was the proportion of patients achieving both SLE Responder Index-4 (SRI-4) and glucocorticoid dose ≤10mg QD at week 24. Additional assessments through week 48 included British Isles Lupus Assessment Group-based Composite Lupus Assessment (BICLA) and Lupus Low Disease Activity State (LLDAS) responses, number of flares, time to first flare, and adverse events. The study enrolled 341 patients. The ABBV-599LD and elsubrutinib arms were discontinued after a planned interim analysis showed lack of efficacy (no safety concerns). More patients achieved the primary endpoint with upadacitinib (54.8%; P=0.028) and ABBV-599HD (48.5%; P=0.081) versus placebo (37.3%). SRI-4, BICLA, and LLDAS response rates were higher for both upadacitinib and ABBV-599HD versus placebo at weeks 24 and 48. Flares were reduced and time to first flare through week 48 was substantially delayed with both upadacitinib and ABBV-599HD versus placebo. No new safety signals were observed beyond those previously reported for upadacitinib or elsubrutinib. Upadacitinib 30mg alone or in combination with elsubrutinib (ABBV-599HD) demonstrated significant improvements in SLE disease activity, reduced flares and were well tolerated through 48 weeks.

Comprehensive analysis of the equatorial ionization anomaly based on global ionospheric maps with a high spatiotemporal resolution

The Equatorial Ionization Anomaly (EIA), a manifestation of Ionospheric plasma irregularities, is closely linked to the equatorial fountain, influenced by solar activity and Earth’s geomagnetic field. While previous studies on EIA have predominantly focused on specific regional analyses using TEC data from GPS stations, revealing correlations between peaks, discrepancies with models, and temporal variations, there exists a gap in comprehensive global statistics, consideration of different solar activity years, and exploration of EIA characteristics across various local time scales. To address these, this study employs high spatiotemporal data from the Global Ionospheric Map (GIM) to comprehensively analyze EIA across different periods of the day during high solar activity in 2014 and low solar activity in 2020. The study delves into the subtle variations of EIA under different solar activity levels and seasonal conditions, focusing on changes in occurrence rate, intensity, and geomagnetic latitude positions concerning longitude, month, and local time. Our study reveals several findings: (1) EIA exhibited more frequent and intense trends during high solar activity years, with higher occurrence rates and intensity observed during the equinoxes; (2) EIA exhibits significant variations across different longitudes and local times, showing systematic patterns in its occurrence rates over time; (3) The crest-to-trough TEC Ratio (CTR) effectively characterizes nighttime EIA intensity, while the crest-to-trough TEC Difference (CTD) is suitable for representing daytime EIA intensity; (4) The temporal changes in EIA positions may be related to electric fields and wind patterns, while differences in longitudes are attributed to variations in the geomagnetic field.

Seismicity and state of stress in NE Arabia

Eastern Arabia exhibits low seismic activity although damaging earthquakes are historically known. Despite the proximity to convergent plate boundaries in the Arabia–Eurasia collision zone, the state of stress in northern Oman with its persistent topography of the Oman Mountains (OM) remains enigmatic. We have revised the earthquake catalogue of northern Oman and confirm the detection and location accuracy of the permanent network by comparison with a temporarily densified network across the OM. For the first time, we infer focal mechanisms (FM) for earthquakes in Oman from P-wave polarities. Seismic activity is high in the Northern OM but diminishes rapidly south of 24.5° N. In the Central and Eastern OM, low-magnitude earthquakes occur along topography bounding faults with mostly transtensional FM. Offshore, seismicity follows NE-trending lines in extension of the Semail Gap and the Masirah Fault Zones, up to the Makran trench. Except for an isolated patch of repeated small-magnitude earthquakes, the western Makran trench is seismically quiet. Inversion of FM confirms a NE–SW direction of maximum horizontal stress that aligns with Arabia–Eurasia convergence. In the Central and Eastern OM, maximum horizontal and vertical stresses are balanced. The topography of the OM appears, therefore, not to be generally sustained by compressional forces.

N-Pyrazolyl- and N-Triazolylamines and -Ureas as Antileishmanial and Antitrypanosomal Drugs.

Three types of modifications of antileishmanial pyrazole lead compounds 7 and 8 were conducted to expand understanding of the relationships between structural features and antileishmanial/antitrypanosomal activity: (1) the pyrazole core was retained or replaced by a 1,2,4-triazole ring; (2) various aryl moieties including 2-fluorophenyl, pyridin-3-yl and pyrazin-2-yl rings were attached at 3-position of the core azole; (3) either arylmethylamino or ureido substituents were introduced at 5-position of the azole core. The synthesis followed established routes starting with esters 9 or 15 and anhydride 21. The synthesized 3-arylpyrazoles and 3-aryl-1,2,4-triazoles had only very low antileishmanial activity. The 2-fluorophenyl-substituted pyrazole 18c revealed the highest antileishmanial activity of this series of compounds, but its IC50 value (20 μM) still indicates low activity. However, low micromolar antitrypanosomal activity was detected for the pyridin-3-yl-substituted pyrazoles 12b (IC50=4.7 μM) and 14a (IC50=2.1 μM). Their IC50 values are comparable with the IC50 values of the reference compounds benznidazole and nifurtimox. Whereas only low unspecific cytotoxicity at the primary peritoneal mouse macrophages (PMM) was detected, considerable cytotoxicity at MRC-5 human fibroblast cells was found for both pyrazoles 12b an 14a. The activity of pyrazole 12b against T. cruzi is 4-fold higher than its unspecific MRC-5 cytotoxicity.

Interaction between Enzymatic Detergent and Textile Metals/Metal Oxide Nanoparticles

aims: This research examines the interactions between metal (Ag) and metal oxide (TiO2 and ZnO) nanoparticles and amylase, cellulase, protease, and lipase as detergent enzymes and their impacts on enzyme activity. background: Nanoparticles are used in industrial products, such as textiles, to induce novel properties, such as antibacterial, antistatic, UV blocking, self-cleaning properties, wrinkle resistance, and water and oil repellent. On the other hand, using enzymes (protease, lipase, amylase, and cellulase) is widespread in detergent industries for washing conditions. objective: The interactions between metal (Ag) and metal oxide (TiO2 and ZnO) nanoparticles and detergent enzymes method: Using a central composite design, a total of 320 experiments under different conditions were conducted to determine the extent of change in enzyme activity. result: Results indicate that lipase had the lowest activity under interaction with silver nanoparticles, while cellulase and protease were most affected by interactions with AgNPs and a-TiO2. The surface response of the examined parameters showed the most effect from the interaction time and temperature and the enzyme/nanoparticle ratio and temperature parameters. conclusion: Further investigations into the effects of nanomaterials and enzymes on the physiology and chemistry of surfaces are suggested. This research results demonstrate that in nanoparticle and enzyme interface, physical, chemical, and biological difference is made in both. The outcome can be used to improve nanoparticle and detergent enzyme interactions in washing surroundings, aiming to retain nanoparticles and enzyme traits. other: -

Formation processes of iron-based layered hydroxide in acid mine drainage and its implications for in-situ arsenate immobilization: Insights and mechanisms

The immobilization of arsenate in transformed minerals depends on their states in acid mine drainage (AMD). In this study, an iron-based layer hydroxide mineral was derived from the transformation of ferrihydrite under co-existing Mg2+ ions in AMD. The immobilization behavior of arsenate on the mineralized LDHm and pre-prepared LDHad was distinguished. 99 % immobilization efficiency was achieved from the mineralized LDHm, maintaining stability without subsequent releases, across initial arsenate concentrations ranging from 10 to 60 mg/L. LDHm outperformed the pre-prepared LDHad, which was synthesized from AMD for arsenate adsorption. Electron energy loss spectroscopy line profiles revealed predominant incorporation of arsenate in the LDHm structure, supported by higher bulk As signals within LDHm. Density functional theory calculations indicated primary arsenate incorporation into LDHm, forming stable bonds with lower energy activation barriers. Importantly, LDHm exhibited a superior electron rearrangement configuration, resulting in enhanced electron state activity and affinity for arsenate. In contrast, arsenate adsorption predominantly occurred on the pre-prepared LDHad, with notable As signals detected particularly at the edges. Adsorption energy evaluation indicated arsenate preference for bonding to Fe3+ sites on LDHad. These findings provide important insights into the role of stable LDH-like minerals for long-term arsenate immobilization in the natural AMD attenuation processes.

Physical activity information-seeking behaviour and barriers in a sample of university undergraduate emerging adults: a cross-sectional survey

BackgroundAccess to physical activity information provides opportunities for enduring and relevant messaging regarding physical activity. This may be a potential vehicle to optimise physical activity participation among emerging adults. This study aimed to characterise the physical activity information-seeking behaviour in a sample of university undergraduate emerging adults.MethodsFive hundred and seventy-five undergraduate students (age = 21.7 ± 1.9 years) participated in the study. Respondents’ physical activity information-seeking behaviour was obtained using an adapted instrument, while physical activity and barriers were assessed using the International Physical Activity Questionnaire and the Exercise Benefits and Barrier Scale.ResultsThree hundred and fifty-one respondents (61%) of respondents sought physical activity information. The majority of these individuals (73.8%) sought physical activity information using social media. After identifying and controlling for confounders including engaging in physical activity programmes and faculty of study, having low physical activity levels was associated with a < 1 likelihood of seeking physical activity information compared to having high physical activity levels (odds ratio = 0.5, 95% confidence interval 0.27–0.87; p = 0.015). However, there was no association between barriers to physical activity and physical activity information-seeking behaviour (odds ratio = 1.17, 95% confidence interval 0.81–1.69; p = 0.40).ConclusionUndergraduate emerging adults seek physical activity information using social media to enhance their physical appearance and health.

The association between physical activity and neck circumference with cardiovascular disease risk in older wheelchair users.

To examine the association between physical activity, neck circumference, and cardiovascular disease risk in older wheelchair users. A cross-sectional study. Sixty-one Korean wheelchair users aged 50 years and older. Physical activity was assessed using a self-administered questionnaire. Neck circumference was measured with a tape ruler. Cardiovascular disease risk was evaluated by calculating the Framingham risk score (FRS) for estimating 10-year cardiovascular disease risk, which was classified as low-moderate (19% or less) or high risk (20% or more). The FRS for 10-year cardiovascular disease risk was inversely related to physical activity (beta [SE] = -0.213 (0.103), p = 0.043) and positively related to neck circumference (beta [SE] = 1.331 ± 0.419, p = 0.003). Binary logistic regression showed that those with low physical activity (odds ratio [95% confidence interval] = 4.256 (1.188~15.243), p = 0.026) or a large neck circumference (odds ratio [95% confidence interval] = 3.645 (1.172~11.338), p = 0.025) had a higher risk for high cardiovascular disease risk compared with those with high physical activity or normal neck circumference. The current study findings suggest that an intervention targeting physical inactivity and upper-body obesity should be implemented to reduce cardiovascular disease risk in older wheelchair users.

Glycoprotein-Specific Polyclonal Antibodies Targeting Machupo Virus Protect Guinea Pigs against Lethal Infection.

Convalescent plasma has been shown to be effective at protecting humans against severe diseases caused by New World (NW) arenaviruses, including Junin virus (JUNV) and Machupo virus (MACV). This plasma contains antibodies against the full complement of structural proteins including the nucleocapsid and envelope glycoproteins (GPcs) consisting of GP1 and GP2. To gain insights into the protective and cross-protective properties of anti-GPc-specific polyclonal antibodies, we evaluated the ability of a DNA vaccine-produced anti-GPc rabbit antisera targeting MACV strain Carvallo to provide heterologous protection against another MACV strain termed Chicava in the Hartley guinea pig model. The neutralizing activity of the rabbit antisera against the heterologous MACV strains Chicava and Mallale was found to be 54-fold and 23-fold lower, respectively, compared to the titer against the homologous MACV strain Carvallo in the PRNT50 assay. Despite lower neutralizing activity against the strain Chicava, the rabbit antisera protected 100% of the guinea pigs from this strain when administered up to four days post-infection, whereas all the control animals succumbed to the disease. Using vesicular stomatitis virus (VSV) particles pseudotyped with MACV GPc, we identified a single amino acid difference at position 122 between the strains Chicava and Carvallo GPc that significantly influenced the neutralization activity of the rabbit antisera. These findings indicate that polyclonal antibodies targeting the MACV glycoproteins can protect against lethal infection in a post-challenge setting. These data will help guide future antibody-based therapeutics development against NW arenaviruses.

Temperature dependent conductivity, dielectric relaxation, electrical modulus and impedance spectroscopy of Ni substituted Na[formula omitted]Zr[formula omitted]Ni[formula omitted]Si[formula omitted]PO[formula omitted]

We investigate the structural, dielectric relaxation, electric modulus and impedance behavior of Ni-doped NASICON ceramic Na3+2xZr2−xNixSi2PO12 (x=0.05–0.2) prepared using the solid-state reaction method. The increase in dielectric constant with temperature and decrease with frequency is explained on the basis of space charge polarization using the two-layer model of Maxwell–Wagner relaxation. The dielectric loss peak at lower temperatures follows the Arrhenius-type behavior with frequency having activation energy of 0.27 ± 0.01 eV of dipolar relaxation, suggests similar type of defects are responsible for all the doped samples. The real (ϵ′) and imaginary (ϵ′′) permittivity variation with frequency shows the broad relaxation behavior indicates the non-Debye type of relaxation in the measured temperature range. The permittivity values decrease with the amount of doping due to the increased number of charge carriers upon Ni doping at the Zr site. The impedance variation with frequency at various temperatures shows two types of relaxation for all the samples correspond to grain and grain boundary contribution in total impedance. The grain contributions are observed at higher frequencies, while grain-boundary contributions occur at the lower side of frequencies. The imaginary part of the electric modulus also shows two types of relaxation peaks for all the samples indicating similar activation energy at low temperatures and variable activation energy at higher temperatures. The fitting of the imaginary modulus using KWW function shows the non-Debye type of relaxation. We find that all modulus curves merge with each other at low temperatures showing a similar type of relaxation, while curves at high temperatures show the dispersed behavior above the peak frequency. The a.c. conductivity data are fitted using the double power law confirming the grain and grain boundary contributions in total conductivity. The double power law exponent variation with temperature shows the small polaron hopping conduction over the measured temperature range for all the doped samples.

Microwave driven steam reforming of biomass model tar based on metal organic frameworks (ZIF-67) derived Co/C catalyst

Tar catalytic removal is a key issue in biomass gasification, which is suffering from catalyst coking and sintering. Microwave technology is attractive due to the high activity on polar molecules and ability to lower activation energy. In this study, the Co/C derived from metal-organic frameworks (ZIF-67) was developed as a bifunctional microwave catalyst that can strengthen the interaction between microwave and tar catalytic reforming, and enhance the anti-coking and sintering ability. The effects of the temperature, heating method, tar concentration, and catalyst support on model tar conversion rate were investigated. The operating conditions at 700 °C and tar concentration lower than 20 g/m3 can reach a promising conversion rate over 90.15 % under microwave irradiation. On the one hand, microwave heating groups performed better in conversion rate and coking compared to conventional heating, due to the active species generated from the microwave plasma. On the other hand, Co/C showed better performance in catalytic activity and sintering stability, due to the highly dispersion of cobalt nanoparticles and the confinement effect of carbon nanotubes on the catalyst surface. These findings proposed a novel approach for efficient biomass tar removal under microwave irradiation, and offered a potential tool to further reveal the mechanism in microwave driven tar steam reforming system.

Tuning the Metal-Support Interaction by Modulating CeO2 Oxygen Vacancies to Enhance the Toluene Oxidation Activity of Pt/CeO2 Catalysts.

In this research, a range of Pt/CeO2 catalysts featuring varying Pt-O-Ce bond contents were developed by modulating the oxygen vacancies of the CeO2 support for toluene abatement. The Pt/CeO2-HA catalyst generated a maximum quantity of Pt-O-Ce bonds (possessed the strongest metal-support interaction), as evidenced by the visible Raman results, which demonstrated outstanding toluene catalytic performance. Additionally, the UV Raman results revealed that the strong metal-support interaction stimulated a substantial increase in oxygen vacancies, which could facilitate the activation of gaseous oxygen to generate abundant reactive oxygen species accumulated on the Pt/CeO2-HA catalyst surface, a conclusion supported by the H2-TPR, XPS, and toluene-TPSR results. Furthermore, the results from quasi-in situ XPS, in situ DRIFTS, and DFT indicated that the Pt/CeO2-HA catalyst with a strong metal-support interaction led to improved mobility of reactive oxygen species and lower oxygen activation energies, which could transfer a large number of activated reactive oxygen species to the reaction interface to participate in the toluene oxidation, resulting in the relatively superior catalytic performance. The approach of tuning the metal-support interaction of catalysts offers a promising avenue to develop highly active catalysts for toluene degradation.

CRISPR-Cas9 screens reveal common essential miRNAs in human cancer cell lines

BackgroundGenome-wide functional screening using the CRISPR-Cas9 system is a powerful tool to uncover tumor-specific and common genetic dependencies across cancer cell lines. Current CRISPR-Cas9 knockout libraries, however, primarily target protein-coding genes. This limits functional genomics-based investigations of miRNA function.MethodsWe designed a novel CRISPR-Cas9 knockout library (lentiG-miR) of 8107 distinct sgRNAs targeting a total of 1769 human miRNAs and benchmarked its single guide RNA (sgRNA) composition, predicted on- and off-target activity, and screening performance against previous libraries. Using a total of 45 human cancer cell lines, representing 16 different tumor entities, we performed negative selection screens to identify miRNA fitness genes. Fitness miRNAs in each cell line were scored using a combination of supervised and unsupervised essentiality classifiers. Common essential miRNAs across distinct cancer cell lines were determined using the 90th percentile method. For subsequent validation, we performed knockout experiments for selected common essential miRNAs in distinct cancer cell lines and gene expression profiling.ResultsWe found significantly lower off-target activity for protein-coding genes and a higher miRNA gene coverage for lentiG-miR as compared to previously described miRNA-targeting libraries, while preserving high on-target activity. A minor fraction of miRNAs displayed robust depletion of targeting sgRNAs, and we observed a high level of consistency between redundant sgRNAs targeting the same miRNA gene. Across 45 human cancer cell lines, only 217 (12%) of all targeted human miRNAs scored as a fitness gene in at least one model, and fitness effects for most miRNAs were confined to small subsets of cell lines. In contrast, we identified 49 common essential miRNAs with a homogenous fitness profile across the vast majority of all cell lines. Transcriptional profiling verified highly consistent gene expression changes in response to knockout of individual common essential miRNAs across a diverse set of cancer cell lines.ConclusionsOur study presents a miRNA-targeting CRISPR-Cas9 knockout library with high gene coverage and optimized on- and off-target activities. Taking advantage of the lentiG-miR library, we define a catalogue of miRNA fitness genes in human cancer cell lines, providing the foundation for further investigation of miRNAs in human cancer.

Metabolic engineering of Saccharomyces cerevisiae for high-level production of (+)-ambrein from glucose.

(+)-Ambrein is the primary component of ambergris, a rare product found in sperm whales (Physeter microcephalus). Microbial production using sustainable resources is a promising way to replace animal extraction and chemical synthesis. We constructed an engineered yeast strain to produce (+)-ambrein de novo. Squalene is a substrate for the biosynthesis of (+)-ambrein. Firstly, strain LQ2, with a squalene yield of 384.4mg/L was obtained by optimizing the mevalonate pathway. Then we engineered a method for the de novo production of (+)-ambrein using glucose as a carbon source by overexpressing codon-optimized tetraprenyl-β-curcumene cyclase (BmeTC) and its double mutant enzyme (BmeTCY167A/D373C), evaluating different promoters, knocking out GAL80, and fusing the protein with BmeTC and squalene synthase (AtSQS2). Nevertheless, the synthesis of (+)-ambrein is still limited, causing low catalytic activity in BmeTC. We carried out a protein surface amino acid modification of BmeTC. The dominant mutant BmeTCK6A/Q9E/N454A for the first step was obtained to improve its catalytic activity. The yield of (+)-ambrein increased from 35.2 to 59.0mg/L in the shake flask and finally reached 457.4mg/L in the 2 L fermenter, the highest titer currently available for yeast. Efficiently engineered strains and inexpensive fermentation conditions for the industrial production of (+)-ambrein. The metabolic engineering tools provide directions for optimizing the biosynthesis of other high-value triterpenes.