A highly selective turn-on fluorescence probe with large Stokes shift for detection of palladium and its applications in environment water and living cells

Nowadays, palladium has been widely used in many fields, which facilitates all aspects of our life. However, it may cause water and soil pollution and bring irreversible damage to the environment and organisms. Developing a fluorescence probe for rapid, highly sensitive and selective detection of palladium is still a poser. In this work, we designed and synthesized a novel fluorescence probe (RHS) for specific detection of palladium. Based on Pd⁰-mediated Tsuji-Trost reaction, the fluorescence probe was constructed by a rhodol derivative as thefluorophore and an allyl carbonate moiety as the specific palladium reactive site. The probe displayed excellent properties for detecting palladium, such as high selectivity and sensitivity, rapid response (20 min) and large Stokes shift (155 nm). The detection limit was determined to be as low as 0.140 μM with a linear range from 20 to 80 μM. After addition of palladium in RHS solution, the color of the solution turned from yellow to blue, indicating palladium could be monitored by the naked eyes. Moreover, probe RHS was successfully applied to palladium detection in environmental water samples. Importantly, with low cytotoxicity and good biocompatibility, the probe could monitor palladium in living cells.

[The effectiveness of psychological intervention on nursing staff' compassion fatigue: a meta-analysis]

Objective: To systematically evaluate the impact of psychological intervention on nursing staff' compassion fatigue. Methods: From March to May 2020, PubMed, Cochrane Library, EMbase, Web of Science, CNKI, VIP, Wanfang and other databases were electronically searched to collect randomized controlled trials (RCTs) on the influence of psychological intervention on nursing staff' compassion fatigue with the main search terms including compassion fatigue, nurs*, psychological intervention, mental intervention, RCT and so on from inception to March 31, 2020. Screened literature, extracted data and assessed the risk of bias of included studies. The Stata 16.0 software was used to calculate the pooled effectiveness of psychological intervention on nursing staff' compassion fatigue. Results: All 13 RCTs were enrolled, including 940 nursing staff. Meta-analysis results demonstrated that the psychological intervention group was superior to the control group in the improvement of the compassion fatigue score (SMD=-0.96, 95%CI: -1.17-0.74, P=0.001) , compassion satisfaction score (SMD=0.61, 95%CI: 0.45-0.77, P=0.002) , burnout score (SMD=-0.46, 95%CI: -0.62-0.29, P=0.006) , secondary trauma score (SMD=-0.40, 95%CI: -0.68-0.12, P=0.020) , and the difference was statistically significant. Subgroup analysis found that the psychological intervention group was more effective than the control group in improving compassion satisfaction score, reducing burnout score and secondary trauma score, and the differences were statistically significant (P<0.05) in different intervention time (<8 weeks and ≥8 weeks) and intervention methods. Conclusion: The psychological intervention can improve the level of compassion satisfaction, and reduce the compassion fatigue among nursing staff, and have a certain preventive effect on compassion fatigue.

Establishment of prediction models for COVID-19 patients in different age groups based on Random Forest algorithm

BACKGROUND

Coronavirus disease 2019 (COVID-19) has rapidly become a global pandemic. Age is an independent factor in death from the disease, and predictive models to stratify patients according to their mortality risk are needed.

AIM

To compare the laboratory parameters of the younger (≤70) and the elderly (>70) groups, and develop death prediction models for the two groups according to age stratification.

DESIGN

A retrospective, single-center observational study.

METHODS

This study included 437 hospitalized patients with laboratory-confirmed COVID-19 from Tongji Hospital in Wuhan, China, 2020. Epidemiological information, laboratory data and outcomes were extracted from electronic medical records and compared between elderly patients and younger patients. First, recursive feature elimination (RFE) was used to select the optimal subset. Then, two random forest (RF) algorithms models were built to predict the prognoses of COVID-19 patients and identify the optimal diagnostic predictors for patients' clinical prognoses.

RESULTS

Comparisons of the laboratory data of the two age groups revealed many different laboratory indicators. RFE was used to select the optimal subset for analysis, from which 11 variables were screened out for the two groups. The RF algorithm were built to predict the prognoses of COVID-19 patients based on the best subset, and the area under ROC curve (AUC) of the two groups is 0.874 (95% CI: 0.833-0.915) and 0.842 (95% CI: 0.765-0.920).

CONCLUSION

Two prediction models for COVID-19 were developed in the patients with COVID-19 based on random forest algorithm, which provides a simple tool for the early prediction of COVID-19 mortality.

Efficient poly(3-hydroxybutyrate-co-lactate) production from corn stover hydrolysate by metabolically engineered Escherichia coli

Poly(3-hydroxybutyrate-co-lactate)[P(3HB-co-LA)], is a biodegradable and biocompatible bioplastic, and the monomeric composition of the copolymer plays an important role in affecting its mechanical properties. Corn stover hydrolysate (CSH), the waste by-product in agriculture, has been considered as an important carbon source for value-added biochemical production. Therefore, the effect of CSH on P(3HB-co-LA) biosynthesis was investigated in this study. Taking CSH as the carbon source, the lactate (LA) fraction in the copolymer reached 7.1 mol% by the engineered stain. The results of shake flask fermentation demonstrated that reducing the activity of electron transport system resulted in a higher LA fraction. Furthermore, we replaced the promoter of the key gene pct_th with ldhA gene promoter, so that the expression of pct_th gene could be dynamically modulated as well as the lactic acid content changed. This study suggests that CSH is a promising carbon source for the production of biodegradable P(3HB-co-LA).

A near-infrared fluorescence turn-on probe based on Michael addition-intramolecular cyclization for specific detection of cysteine and its applications in environmental water and milk samples and living cells

Owing to its important biological functions in many physiological and pathological processes, it is necessary to develop efficient and appropriate detection methods for monitoring the levels of Cys in biological systems. Based on this, a novel rhodol-isophorone derivative (RHI) was designed and synthesized as a reaction-based fluorescence probe for specific detection of Cys with high sensitivity and large Stokes shift (155 nm). This probe was composed of an acrylate moiety (recognition group) and a rhodol-isophorone derivative (fluorophore). Probe RHI could react with Cys rapidly (15 min) with a 100-fold fluorescence enhancement. The limit of detection value was calculated to be 0.168 μM. When Cys was added, the color of the probe RHI solution turned from yellow to blue, indicating that Cys could be monitored by the naked eye. In addition, probe RHI was successfully utilized for detecting Cys in environmental water and milk samples. More importantly, the probe could be applied to imaging Cys in living cells with low cytotoxicity and good biocompatibility.

Λ_{c}^{+} Production and Baryon-to-Meson Ratios in pp and p-Pb Collisions at sqrt[s_{NN}]=5.02 TeV at the LHC

The prompt production of the charm baryon Λ_{c}^{+} and the Λ_{c}^{+}/D^{0} production ratios were measured at midrapidity with the ALICE detector in pp and p-Pb collisions at sqrt[s_{NN}]=5.02  TeV. These new measurements show a clear decrease of the Λ_{c}^{+}/D^{0} ratio with increasing transverse momentum (p_{T}) in both collision systems in the range 2<p_{T}<12  GeV/c, exhibiting similarities with the light-flavor baryon-to-meson ratios p/π and Λ/K_{S}^{0}. At low p_{T}, predictions that include additional color-reconnection mechanisms beyond the leading-color approximation, assume the existence of additional higher-mass charm-baryon states, or include hadronization via coalescence can describe the data, while predictions driven by charm-quark fragmentation processes measured in e^{+}e^{-} and e^{-}p collisions significantly underestimate the data. The results presented in this Letter provide significant evidence that the established assumption of universality (colliding-system independence) of parton-to-hadron fragmentation is not sufficient to describe charm-baryon production in hadronic collisions at LHC energies.

[Clinical features and treatment efficacy of infantile renal tumors: a multicenter retrospective study]

Objective: To further understand the clinical features, treatment efficacy and risk factors for poor prognosis in infantile-onset renal tumors. Methods: Clinical data of 45 cases of infantile-onset renal tumors from June 2011 to November 2019 in Peking University First Hospital, Beijing Children's Hospital, Beijing Tongren Hospital and Beijing Shijitan Hospital were analyzed retrospectively. The clinical features were summarized and the prognoses were evaluated. Multi-disciplinary diagnosis and treatment was used, including surgery, chemotherapy and radiotherapy. Kaplan-Meier analysis was used to calculate the overall survival rate and the event-free survival rate, while the chi-square test was used to analyze the risk factors for poor prognosis. Results: Among 45 patients, 24 were males and 21 females. The age of onset was 7 (ranged 3-11) months, and the length of tumor at initial diagnosis was 9.7 (ranged 4.9-25.0)cm. The International Society of Pediatric Oncology (SIOP) staging: 5 cases (11%) were in stage Ⅰ, 22 cases in stage Ⅱ (49%), 8 cases in stage Ⅲ (18%), 6 cases in stage Ⅳ (13%), and 4 cases in stage Ⅴ (9%). Risk groups included 5 cases (11%) in the low-risk group, 22 cases (49%) in the intermediate-risk group, and 18 cases (40%) in the high-risk group. Forty-four cases (98%) did not receive preoperative biopsy, 26 cases (58%) received preoperative chemotherapy, 39 cases (87%) received postoperative chemotherapy, and 2 cases (4%) received three-dimensional conformal radiotherapy. The 5-year overall survival rate was (83±7)%, and the 5-year event-free survival rate was (76±8)%. Hematuria as the first symptom (3/8 vs. 83% (30/36), χ²=7.005, P=0.024), tumor long diameter≤8 cm (5/11 vs. 85% (28/33), χ²=5.606, P=0.027) and high-risk pathological group (7/18 vs.100% (26/26), χ²=21.928, P<0.01) were risk factors for poor prognosis of children with renal tumors in this group. Conclusion: The prognosis of children with infantile-onset renal tumors is fairly well, nevertheless the prognosis is poor in patients with hematuria as the first symptom and in high-risk pathological group.

Screening of engineered Pichia pastoris mutant with enhanced production of a functional rFIP-glu protein and investigating its potential bioactivities

An engineered Pichia pastoris GS115 with a FIP-glu gene was mutated using ultraviolet (UV) radiation, and a high-throughput screening method was established for screening of high-yield strains. Meanwhile, a preliminary study was conducted to determine the bioactivity of the rFIP-glu. Based on OD₆₀₀ value and the mortality of engineered P. pastoris GS115, the best UV irradiation time was determined. Bradford method and SDS-PAGE method were employed to analyze the concentration and yield of rFIP-glu. Melanoma B16 cells were employed to evaluate the biological activities of rFIP-glu in vitro. Results showed that the protein yield of the best mutant #4-336 screened from 3680 mutant strains increased from 242 to 469 μg ml^-1 . In vitro assays of biological activity indicated that rFIP-glu had significant toxicity and possessed the ability to affect melanin content and enhance tyrosinase activity in B16 cells. In conclusion, an effective high-throughput screening approach was established for screening mutant strains. The screened mutant possesses a good ability to enhance the production of rFIP-glu, and recombinant proteins display a better biological activity on melanoma B16 cells. The engineered P. pastoris mutant seems promising as a potential source for industrial production of rFIP-glu and should be a candidate industrial strain for further study.

Overexpressing CCW12 in Saccharomyces cerevisiae enables highly efficient ethanol production from lignocellulose hydrolysates

A Saccharomyces cerevisiae strain CCW12^OE was constructed by overexpressing CCW12 in a previously reported strain WXY70 harboring six xylose utilization genes. CCW12^OE produced an optimal ethanol yield of 98.8% theoretical value within 48 h in a simulated corn stover hydrolysate. CCW12^OEwas comprehensively evaluated for ethanol production in Miscanthus, maize and corncob hydrolysates, among which a 96.1% theoretical value was achieved within 12 h in corncob hydrolysates. Under normal growth conditions, CCW12^OE did not display altered cell morphology; however, in the presence of acetate, CCW12^OE maintained relatively intact cell structure and increased cell wall thickness by nearly 50%, while WXY70 had abnormal cell morphology and reduced cell wall thickness by nearly 50%. Besides, CCW12^OE had higher fermentation capacity than that of WXY70 in undetoxified and detoxified hydrolysates with both aerobic and anaerobic conditions, demonstrating that CCW12 overexpression alone exhibits improved stress resistance and better fermentation performance.

Valorization of lignin components into gallate by integrated biological hydroxylation, O-demethylation, and aryl side-chain oxidation

Converting lignin components into a single product is a promising way to upgrade lignin. Here, an efficient biocatalyst was developed to selectively produce gallate from lignin components by integrating three main reactions: hydroxylation, O-demethylation, and aryl side-chain oxidation. A rationally designed hydroxylase system was first introduced into a gallate biodegradation pathway–blocked Rhodococcus opacus mutant so that gallate accumulated from protocatechuate and compounds in its upper pathways. Native and heterologous O-demethylation systems were then used, leading to multiple lignin-derived methoxy aromatics being converted to gallate. Furthermore, an aryl side-chain oxidase was engaged to broaden the substrate spectrum. Consequently, the developed biocatalyst showed that gallate yields as high as 0.407 and 0.630 g of gallate per gram of lignin when alkaline-pretreated lignin and base-depolymerized ammonia fiber explosion lignin were applied as substrates, respectively. These results suggested that this rationally developed biocatalyst enabled the lignin valorization process to be simple and efficient.

Multiharmonic Correlations of Different Flow Amplitudes in Pb-Pb Collisions at sqrt[s_{NN}]=2.76 TeV

The event-by-event correlations between three flow amplitudes are measured for the first time in Pb-Pb collisions, using higher-order symmetric cumulants. We find that different three-harmonic correlations develop during the collective evolution of the medium when compared to correlations that exist in the initial state. These new results cannot be interpreted in terms of previous lower-order flow measurements since contributions from two-harmonic correlations are explicitly removed in the new observables. A comparison to Monte Carlo simulations provides new and independent constraints for the initial conditions and system properties of nuclear matter created in heavy-ion collisions.

Efficient Preparation of Sophorolipids and Functionalization with Amino Acids to Furnish Potent Preservatives

The development of new preservatives is an ongoing investigation in the food industry, especially those which are safe and environmentally friendly. In this study, biosurfactant sophorolipids (SLs) functionalized with amino acids were developed as efficient preservative agents. SLs were first isolated from fermentation broth by Candida bombicola ATCC 22214, hydrolyzed, and purified by extraction. The typical recovery is around 70%, while the extracted material consists of over 90% deacetylated acidic SLs (SL-COOH). Four types of SL derivatives were then synthesized via dicyclohexylcarbodiimide amidation reactions from prepared SL-COOH. Among the derivatives produced, the arginine SL conjugates (SL-d-Arg) displayed the highest activity against Gram-positive bacteria and fungi and even inhibited the cell growth of Gram-negative bacteria and mildew. Furthermore, the arginine conjugates performed the broadest antimicrobial activity among the derivatives evaluated. The sterilization dosage of the arginine conjugates against the food-spoilage pathogen Bacillus spp. was 63-125 mg/L, in contrast to 250 mg/L for the enterotoxin producer Staphylococcus aureus and 500 mg/L for fungi. More importantly, SL-d-Arg displayed excellent biocompatibility, with a therapeutic index of over 7.94. SL-d-Arg has excellent potential as an alternative to traditional chemical preservatives.

Manganese promoted wheat straw decomposition by regulating microbial communities and enzyme activities

AIMS

This study investigated the dose-effect of manganese (Mn) addition on wheat straw (WS) decomposition, and explored the potential mechanisms of Mn involved in the acceleration of WS decomposition in regards to the soil microbial communities and enzyme activities.

METHODS AND RESULTS

A 180-day incubation experiment was performed to examine the decomposition of WS under four Mn levels, that is, 0, 0.25, 1 and 2 mg g^-1 . The effects of microbial communities and enzyme activities were evaluated using control (0 mg g^-1 ) and Mn (0.25 mg g^-1 ) treatments. Our results revealed that Mn (0.25 mg g^-1 ) addition significantly increased WS decomposition, and enhanced the release of carbon and nitrogen. Optimal Mn addition (0.25 mg g^-1 ) also caused significant increases in the activity of neutral xylanase (NEX), laccase (Lac), manganese peroxidase (MnP) and lignin peroxidase (LiP) within the incubation period. Mn (0.25 mg g^-1 ) addition also enriched some operational taxonomic units (OTUs) that, in turn, had the potential ability to decompose crop straw, such as secreting lignocellulolytic enzymes.

CONCLUSIONS

Mn (0.25 mg g^-1 ) could promote WS decomposition through enrichment of the microbial species involved in biomass decomposition, which enhanced the lignocellulose-degrading enzyme activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides evidence for Mn to promote WS biodegradation after Mn application, opening new windows to improve the utilization efficiency of crop residues.

P–757 The risk of aspirin and prednisone using in women with antithyroid antibodies undergoing assisted reproductive technology

Study question

Is it safe using aspirin (A) and prednisone (P) before pregnancy among women with antithyroid antibodies (ATAbs) undergoing assisted reproductive technology?

Summary answer

Combination therapy of aspirin and prednisone didn’t improve likelihood of clinical pregnancy, but increased miscarriage rate.

What is known already

Compared with women with negative-ATAb, women with positive-ATAb had a lower live birth rate and a higher miscarriage rate. Insufficient evidence existed to determine whether aspirin and prednisone therapy improved the success of pregnancy following assisted reproductive technology (ART) in ATAb-positive euthyroid women. Aspirin and prednisone were used frequently in clinical practice, but the use of these medicines before pregnancy during ART process is still controversial, and the risks of these medicines were not well understood.

Study design, size, duration

A prospective study involving 268 women with unexplained reason for infertility who tested positive for antithyroperoxidase antibody (TPOAb) and/or thyroglobulin antibody (TgAb) were being treated for infertility at the Second Affiliated Hospital of Zhejiang University School of Medicine, Ningbo Women and Children’s Hospital and People’s Hospital of Jinhua from October 2017 to July 2020. Their TSH level ranged from 0.35–4.0mIU/ml and they all underwent fresh embryo transfer.

Participants/materials, setting, methods

Overall, a total of 268 ATAb-positive women were divided 2 groups: group A: no treatment; B: A+P. Both medicines were used in the lowest effective dose. Between the two groups, we measured oocytes retrieved, fertilization rate, high-quality embryo rate, blastulation rate, cleavage rate,implantation rate, likelihood of clinical pregnancy and miscarriage rate. Kruskal-Wallis test was used in nonnormally distributed variables, and the χ2 test or Fisher exact test was used to compare categorical variables.

Main results and the role of chance

A total of 268 infertile women with unexplained reason who tested positive for TPOAb and/or TgAb were recruited in our study. According to assignment, they were divided into two groups. All women in different groups had the similar age, BMI, number of miscarriage and duration of infertility. Levels of FSH, AMH, TSH, FT4, FT3, fibrinogen and d-dimer were similar in all groups. The use of A+P reduced cleavage rate (F = 23.982, P &lt; 0.001) and implantation rate (F = 4.388, P = 0.036). The fertilization rate (P = 0.407), high-quality embryo rate (P = 0.208) and blastulation rate (P = 0.157) were not influenced by the use of medication. In this study, likelihood of clinical pregnancy (P = 0.066) did not change significantly after therapy, and miscarriage rate (P = 0.042) increased after medical treatment.

Limitations, reasons for caution

Firstly, Aspirin is just one representation of anticoagulation therapy, so additional consideration of low molecular heparin should also be considered. Secondly, further randomized controlled trials of aspirin and prednisone alone are needed.

Wider implications of the findings: In this study, use of A+P showed no positive effect, and reduced cleavage rate and implantation rate, while increased miscarriage rate. So, the use of medication for interfile women should be cautious.

Trial registration number

n/a

[A multicenter, randomized, double-masked, placebo-controlled trial of compound wild chrysanthemum eye masks for mild and moderate dry eye]

Objective: To investigate the clinical efficacy and safety of compound wild chrysanthemum eye masks for mild and moderate dry eye. Methods: In this double-masked, multicenter, placebo-controlled, randomized trial, middle-aged and elderly patients with mild and moderate dry eye were enrolled from six hospitals (Xiamen Eye Center of Xiamen University, China-Japan Friendship Hospital, Peking Union Medical College Hospital, Wangjing Hospital of China Academy of Chinese Medical Sciences, Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine and Hebei Eye Hospital). The patients were assigned to the compound wild chrysanthemum eye mask group and the eye mask simulator group based on the random number table. Subjective symptoms of dry eye, visual acuity, break-up time (BUT), Schirmer Ⅰ test, and corneal fluorescent staining were evaluated in all patients before treatment and at 1 and 2 weeks after treatment. All adverse reactions during the treatment and follow-up were recorded. Results: A total of 120 patients were enrolled. Among them, 112 subjects were included for statistical analyses after the exclusion of 8 subjects who were lost for follow-up or had an adverse event, with an age of (54.26±7.44) years. All the indicators were equally comparable between the two groups. Before treatment and at 1 and 2 weeks after treatment, the median (lower quartile, upper quartile) of total score of questionnaires in the eye mask group was 14.50 (10.00, 19.00), 9.00 (5.00, 14.00) and 7.00 (4.00, 10.00), respectively, and that in the control group was 14.00 (9.00, 22.50), 12.00 (6.00, 20.00) and 10.00 (3.50, 17.00), respectively. The score decreased significantly in both groups after 1 week (t=9.1604, S=398.00; P<0.01) and 2 weeks (S=681.00, 575.50; P<0.05) of treatment. The total score of questionnaires in the eye mask group was significantly lower than that in the control group (Z=3.27, 2.81; P<0.05) after treatment. After 1 week of treatment, the average BUT of the eye mask group was (5.71±2.31) s, which was significantly longer than that before treatment (5.06±2.00) s (S =208.50, P<0.05). But there was no significant difference in the control group (S=150.00, P>0.05). After 2 weeks of treatment, there was statistically significant difference in BUT between the two groups (S=407.00, t=3.07; P<0.01). After 1 week of the treatment, the amount of tear secretion in the eye mask group [(6.88±4.78) mm] was significantly larger than that before treatment (S=196.50, P<0.05), while the control group [(6.80±5.85) mm] showed no significant difference (S=55.00, P<0.05). After 2 weeks of the treatment, the amount increased significantly to (7.43±4.86) mm and (7.29±4.56) mm, respectively, in both groups (t=-3.29, -2.26; P<0.05). The difference in the average BUT, Schirmer Ⅰ test result and corneal fluorescent staining between both groups was not statistically significant at each time point. Five mild adverse events occurred, including 2 adverse events (2 times, 3.51%) in the eye mask group and 3 adverse events (4 times, 5.36%) in the control group. Conclusions: Compound wild chrysanthemum eye masks can effectively improve the symptoms and physical signs of mild and moderate dry eye and can be used as an auxiliary treatment. (Chin J Ophthalmol, 2021, 57: 601-607).

Soft-Dielectron Excess in Proton-Proton Collisions at sqrt[s]=13 TeV

A measurement of dielectron production in proton-proton (pp) collisions at sqrt[s]=13  TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron (ee) invariant mass m_{ee} and pair transverse momentum p_{T,ee} that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of m_{ee}, p_{T,ee}, and event multiplicity dN_{ch}/dη. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured η/π^{0} ratio in pp and proton-nucleus collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at 0.15<m_{ee}<0.6  GeV/c^{2} and for p_{T,ee}<0.4  GeV/c indicates an enhancement of soft dielectrons, reminiscent of the "anomalous" soft-photon and soft-dilepton excess in hadron-hadron collisions reported by several experiments under different experimental conditions. The enhancement factor over the hadronic cocktail amounts to 1.61±0.13(stat)±0.17(syst,data)±0.34(syst,cocktail) in the ALICE acceptance. Acceptance-corrected excess spectra in m_{ee} and p_{T,ee} are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.

Increased mixing intensity is not necessary for more efficient cellulose hydrolysis at high solid loading

To enhance the cellulose hydrolysis at high solid loadings, an increased mixing intensity is generally required for the high solid loading hydrolysis, while it leads to higher energy consumption. In this study, the impact of mixing intensity on cellulose conversion during hydrolysis at different solid loadings were systematically studied. It was found that the increased mixing intensity is not necessary for more efficient cellulose hydrolysis. For cellulose hydrolysis at higher solid loadings, a lower mixing intensity is needed for a higher cellulose conversion. Although the increased mixing intensity promoted enzyme adsorption, it strengthened product inhibition and caused severer enzyme deactivation. Besides, mixing at the initial stage of cellulose hydrolysis was more crucial, while continuous mixing throughout the hydrolysis was not required for more efficient cellulose hydrolysis. Based on the mechanism study, a combined mixing strategy was developed to achieve efficient cellulose hydrolysis with about two-third reduction in energy consumption.

Combined adaptive evolution and transcriptomic profiles reveal aromatic aldehydes tolerance mechanisms in Yarrowia lipolytica

Yarrowia lipolytica is an efficient oleaginous yeast, whereas its activity is typically reduced by inhibitors present in lignocellulosic hydrolysate. Understanding the response mechanism of Y. lipolytica to hydrolysate inhibitors and developing inhibitor tolerant strains are vital to lignocellulose valorization by this promising species. In this study, through adaptive laboratory evolution on three representative aromatic aldehyde inhibitors, evolved strains were obtained. Fermentation phenotype suggested that aromatic aldehydes conversion was one main reason for high tolerance of adapted strains. Transcriptome profiling analysis and reverse metabolic engineering confirmed that overexpressing the aldehyde ketone reductase gene YALI0_B07117g and aldehyde dehydrogenase gene YALI0_B01298g effectively converted aromatic aldehyde to corresponding alcohols and acids. The potential degradation pathways for aromatic aldehyde inhibitors in Y. lipolytica XYL+ were then discussed. This study provided insights to the aromatic aldehyde degradation in Y. lipolytica and a reliable basis for the development of aromatic aldehyde tolerant strains.

Elliptic Flow of Electrons from Beauty-Hadron Decays in Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV

The elliptic flow of electrons from beauty hadron decays at midrapidity (|y|<0.8) is measured in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV with the ALICE detector at the LHC. The azimuthal distribution of the particles produced in the collisions can be parametrized with a Fourier expansion, in which the second harmonic coefficient represents the elliptic flow, v_{2}. The v_{2} coefficient of electrons from beauty hadron decays is measured for the first time in the transverse momentum (p_{T}) range 1.3-6  GeV/c in the centrality class 30%-50%. The measurement of electrons from beauty-hadron decays exploits their larger mean proper decay length cτ≈500  μm compared to that of charm hadrons and most of the other background sources. The v_{2} of electrons from beauty hadron decays at midrapidity is found to be positive with a significance of 3.75  σ. The results provide insights into the degree of thermalization of beauty quarks in the medium. A model assuming full thermalization of beauty quarks is strongly disfavored by the measurement at high p_{T}, but is in agreement with the results at low p_{T}. Transport models including substantial interactions of beauty quarks with an expanding strongly interacting medium describe the measurement within uncertainties.

Engineered Polyploid Yeast Strains Enable Efficient Xylose Utilization and Ethanol Production in Corn Hydrolysates

The reported haploid Saccharomyces cerevisiae strain F106 can utilize xylose for ethanol production. After a series of XR and/or XDH mutations were introduced into F106, the XR-K270R mutant was found to outperform others. The corresponding haploid, diploid, and triploid strains were then constructed and their fermentation performance was compared. Strains F106-KR and the diploid produced an ethanol yield of 0.45 and 0.48 g/g total sugars, respectively, in simulated corn hydrolysates within 36 h. Using non-detoxicated corncob hydrolysate as the substrate, the ethanol yield with the triploid was approximately sevenfold than that of the diploid at 40°C. After a comprehensive evaluation of growth on corn stover hydrolysates pretreated with diluted acid or alkali and different substrate concentrations, ethanol yields of the triploid strain were consistently higher than those of the diploid using acid-pretreatment. These results demonstrate that the yeast chromosomal copy number is positively correlated with increased ethanol production under our experimental conditions.