High-Level Production of l-Methionine by Dynamic Deregulation of Metabolism with Engineered Nonauxotroph Escherichia coli

l-Methionine is the only sulfur-containing amino acid among the essential amino acids, and it is mainly produced by the chemical method in industry so far. The fermentation production of l-methionine by genetically engineered strains is an attractive alternative. Due to the complex metabolic mechanism and multilevel regulation of the synthesis pathway in the organism, the fermentation production of l-methionine by genetically engineered strains was still not satisfied. In this study, the biosynthesis pathway of l-methionine was regulated based on the previous studies. As the competitive pathway and an essential amino acid for cell growth, the biosynthesis pathway of l-lysine was first repaired by complementation of the lysA gene in situ on the genome and then replaced the in situ promoter with the dynamically regulated promoter P_fliA to construct a nonauxotroph strain. In addition, the central metabolic pathway and l-cysteine catabolism pathway were further modified to promote the cell growth and enhance the l-methionine production. Finally, the l-methionine fermentation yield in a 5 L bioreactor reached 17.74 g/L without adding exogenous amino acids. These strategies can effectively balance the contradiction between cell growth and l-methionine production and alleviate the complexity of fermentation operation and the cost with auxotroph strains, which provide a reference for the industrial production of l-methionine by microbial fermentation.

Bone age recognition based on mask R-CNN using xception regression model

Background and Objective: Bone age detection plays an important role in medical care, sports, judicial expertise and other fields. Traditional bone age identification and detection is according to manual interpretation of X-ray images of hand bone by doctors. This method is subjective and requires experience, and has certain errors. Computer-aided detection can effectually enhance the validity of medical diagnosis, especially with the fast development of machine learning and neural network, the method of bone age recognition using machine learning has gradually become the focus of research, which has the advantages of simple data pretreatment, good robustness and high recognition accuracy. Methods: In this paper, the hand bone segmentation network based on Mask R-CNN was proposed to segment the hand bone area, and the segmented hand bone region was directly input into the regression network for bone age evaluation. The regression network is using an enhancd network Xception of InceptionV3. After the output of Xception, the convolutional block attention module is connected to refine the feature mapping from channel and space to obtain more effective features. Results: According to the experimental results, the hand bone segmentation network model based on Mask R-CNN can segment the hand bone region and eliminate the interference of redundant background information. The average Dice coefficient on the verification set is 0.976. The mean absolute error of predicting bone age on our data set was only 4.97 months, which exceeded the accuracy of most other bone age assessment methods. Conclusion: Experiments show that the accuracy of bone age assessment can be enhancd by using the Mask R-CNN-based hand bone segmentation network and the Xception bone age regression network to form a model, which can be well applied to actual clinical bone age assessment.

Mining and Characterization of Thermophilic Glucose Isomerase Based on Virtual Probe Technology

Fructose, which is produced by the isomerization of glucose isomerase, is a crucial precursor for the biosynthesis of rare sugars. In this study, thermophilic glucose isomerases (GI) from Caldicellulosiruptor acetigenus (CAGI), Thermoanaerobacter thermocopriae (TTGI), and Thermotoga petrophila (TPGI) were screened from GenBank database by a virtual probe and were successfully expressed in Escherichia coli BL21(DE3). The results of characterization demonstrated that the optimal pH for CAGI and TTGI were 8.0 and were maintained at 80% in a slightly acidic environment. The relative residual activities of CAGI and TTGI were found to be 40.6% and 52.6%, respectively, following an incubation period of 24 h at 90 ℃. Furthermore, CAGI and TTGI exhibited superior catalytic performance that their reaction equilibrium both reached only after an hour at 85 ℃ with 200 g/L glucose, and the highest conversion rates were 54.2% and 54.1%, respectively. This study identifies competitive enzyme candidates for fructose production in the industry with appreciable cost reduction.

Voluntary Deep Inspiration Breath-Hold (VDIBH) Whole-Breast Irradiation Assisted by Optical Surface Monitoring System (OSMS) in Patients With Left-Sided Breast Cancer: A Prospective Phase II Study

Objectives: To investigate the dosimetric advantages of the voluntary deep inspiration breath-hold technique assisted by optical surface monitoring system for whole breast irradiation in left breast cancer after breast-conserving surgery and verify the reproducibility and acceptability of this technique. Methods: Twenty patients with left breast cancer receiving whole breast irradiation after breast-conserving surgery were enrolled in this prospective phase II study. Computed tomography simulation was performed during both free breathing and voluntary deep inspiration breath-hold for all patients. Whole breast irradiation plans were designed, and the volumes and doses of the heart, left anterior descending coronary artery, and lung were compared between free breathing and voluntary deep inspiration breath-hold. Cone beam computed tomography was performed for the first 3 treatments, then weekly during voluntary deep inspiration breath-hold treatment to evaluate the accuracy of the optical surface monitoring system technique. The acceptance of this technique was evaluated with in-house questionnaires completed by patients and radiotherapists. Results: The median age was 45 (27-63) years. All patients received hypofractionated whole breast irradiation using intensity-modulated radiation therapy up to a total dose of 43.5 Gy/2.9 Gy/15f. Seventeen of the 20 patients received concomitant tumor bed boost to a total dose of 49.5 Gy/3.3 Gy/15f. Voluntary deep inspiration breath-hold showed a significant decrease in the heart mean dose (262 ± 163 cGy vs 515 ± 216 cGy, P < .001) and left anterior descending coronary artery (1191 ± 827 cGy vs 1794 ± 833 cGy, P < .001). The median delivery time of radiotherapy was 4 (1.5-11) min. The median deep breathing cycles were 4 (2-9) times. The average score for acceptance of voluntary deep inspiration breath-hold by patients and radiotherapists was 8.7 ± 0.9 (out of 12) and 10.6 ± 3.2 (out of 15), respectively, indicating good acceptance by both. Conclusions: The voluntary deep inspiration breath-hold technique for whole breast irradiation after breast-conserving surgery in patients with left breast cancer significantly reduces the cardiopulmonary dose. Optical surface monitoring system-assisted voluntary deep inspiration breath-hold is reproducible and feasible and showed good acceptance by both patients and radiotherapists.

Study of the Semileptonic Decay Λ_{c}^{+}→Λe^{+}ν_{e}

The study of the Cabibbo-favored semileptonic decay Λ_{c}^{+}→Λe^{+}ν_{e} is reported using a 4.5  fb^{-1} data sample of e^{+}e^{-} annihilations collected at center-of-mass energies ranging from 4.600 GeV to 4.699 GeV with the BESIII detector at the BEPCII collider. The branching fraction of the decay is measured to be B(Λ_{c}^{+}→Λe^{+}ν_{e})=(3.56±0.11_{stat}±0.07_{syst})%, which is the most precise measurement to date. Furthermore, we perform an investigation of the internal dynamics in Λ_{c}^{+}→Λe^{+}ν_{e}. We provide the first direct comparisons of the differential decay rate and form factors with those predicted from lattice quantum chromodynamics (LQCD) calculations. Combining the measured branching fraction with a q^{2}-integrated rate predicted by LQCD, we determine |V_{cs}|=0.936±0.017_{B}±0.024_{LQCD}±0.007_{τ_{Λ_{c}}}.

[Application status of CFD technology in occupational hazard control]

In the process of occupational hazard management, computational fluid dynamics technology can be used to reflect the distribution pattern of occupational hazards in the production process, so as to quickly and accurately guide the formulation of occupational disease prevention and control programs. This paper summarizes and analyzes the current research results on the prevention and control of occupational hazards in workplaces through computational fluid dynamics technology, and describes the application of these research results in the process of occupational disease prevention and control. On this basis, this paper presents the problems and application limitations of existing research and points out the future key research directions, which are of great reference value for guiding further systematic and in-depth research on simulation, experimentation and management of occupational hazards that can cause occupational diseases.

Measurement of the Absolute Branching Fraction and Decay Asymmetry of Λ→nγ

The radiative hyperon decay Λ→nγ is studied using (10087±44)×10^{6}  J/ψ events collected with the BESIII detector operating at BEPCII. The absolute branching fraction of the decay Λ→nγ is determined to be (0.832±0.038_{stat}±0.054_{syst})×10^{-3}, which is a factor of 2.1 lower and 5.6 standard deviations different than the previous measurement. By analyzing the joint angular distribution of the decay products, the first determination of the decay asymmetry α_{γ} is reported with a value of -0.16±0.10_{stat}±0.05_{syst}.

Observation of an Isoscalar Resonance with Exotic J^{PC}=1^{-+} Quantum Numbers in J/ψ→γηη^{'}

Using a sample of (10.09±0.04)×10^{9}  J/ψ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay J/ψ→γηη^{'} is performed. The first observation of an isoscalar state with exotic quantum numbers J^{PC}=1^{-+}, denoted as η_{1}(1855), is reported in the process J/ψ→γη_{1}(1855) with η_{1}(1855)→ηη^{'}. Its mass and width are measured to be (1855±9_{-1}^{+6})  MeV/c^{2} and (188±18_{-8}^{+3})  MeV, respectively, where the first uncertainties are statistical and the second are systematic, and its statistical significance is estimated to be larger than 19σ.

Multivariate modular metabolic engineering for enhanced gibberellic acid biosynthesis in Fusarium fujikuroi

Gibberellic acid (GA3) is one of natural phytohormones, widely used in agriculture and downstream fields. Qualified for the nature productivity, Fusarium fujikuroi was currently employed for the industrial biotransformation from agriculture residues into GA3. Herein, Multivariate modular metabolic engineering (MMME) was assigned to reconstitute the metabolic balance in F. fujikuroi for enhancing GA3 production. Three modules including precursor pool, cluster-specific channel and P450-mediated oxidation in GA3 biosynthetic pathway were defined and optimized separately. The enhancement of both precursor pool and cluster-specific channel pushed metabolic flux transfer into the GA3-specific pathway. Moreover, both introduction of Vitreoscilla hemoglobin and reinforcement of NADPH-dependent cytochrome P450 reductase facilitated oxidation cofactor transfer and subsequently boosted mycelium growth and GA3 biosynthesis. Integration of three modules in the engineered strain accumulated 2.89 g/L GA3 in shake flask via submerged fermentation, presenting a promising modular metabolic engineering model for efficient microbial transformation in agro-industrial application.

Observation of an a_{0}-like State with Mass of 1.817 GeV in the Study of D_{s}^{+}→K_{S}^{0}K^{+}π^{0} Decays

Using e^{+}e^{-} annihilation data corresponding to an integrated luminosity of 6.32  fb^{-1} collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform the first amplitude analysis of the decay D_{s}^{+}→K_{S}^{0}K^{+}π^{0} and determine the relative branching fractions and phases for intermediate processes. We observe an a_{0}-like state with mass of 1.817 GeV in its decay to K_{S}^{0}K^{+} for the first time. In addition, we measure the ratio {B[D_{s}^{+}→K[over ¯]^{*}(892)^{0}K^{+}]/B[D_{s}^{+}→K[over ¯]^{0}K^{*}(892)^{+}]} to be 2.35_{-0.23stat}^{+0.42}±0.10_{syst}. Finally, we provide a precision measurement of the absolute branching fraction B(D_{s}^{+}→K_{S}^{0}K^{+}π^{0})=(1.46±0.06_{stat}±0.05_{syst})%.

Precise Measurements of Decay Parameters and CP Asymmetry with Entangled Λ-Λ[over ¯] Pairs

Based on 10 billion J/ψ events collected at the BESIII experiment, a search for CP violation in Λ decay is performed in the difference between CP-odd decay parameters α_{-} for Λ→pπ^{-} and α_{+} for Λ[over ¯]→p[over ¯]π^{+} by using the process e^{+}e^{-}→J/ψ→ΛΛ[over ¯]. With a five-dimensional fit to the full angular distributions of the daughter baryon, the most precise values for the decay parameters are determined to be α_{-}=0.7519±0.0036±0.0024 and α_{+}=-0.7559±0.0036±0.0030, respectively. The Λ and Λ[over ¯] averaged value of the decay parameter is extracted to be α_{avg}=0.7542±0.0010±0.0024 with unprecedented accuracy. The CP asymmetry A_{CP}=(α_{-}+α_{+})/(α_{-}-α_{+}) is determined to be -0.0025±0.0046±0.0012, which is one of the most precise measurements in the baryon sector. The reported results for the decay parameter will play an important role in the studies of the polarizations and CP violations for the strange, charmed and beauty baryons.

First Observation of the Direct Production of the χ_{c1} in e^{+}e^{-} Annihilation

We study the direct production of the J^{PC}=1^{++} charmonium state χ_{c1}(1P) in electron-positron annihilation by carrying out an energy scan around the mass of the χ_{c1}(1P). The data were collected with the BESIII detector at the BEPCII collider. An interference pattern between the signal process e^{+}e^{-}→χ_{c1}(1P)→γJ/ψ→γμ^{+}μ^{-} and the background processes e^{+}e^{-}→γ_{ISR}J/ψ→γ_{ISR}μ^{+}μ^{-} and e^{+}e^{-}→γ_{ISR}μ^{+}μ^{-} is observed by combining all the data samples. The χ_{c1}(1P) signal is observed with a significance of 5.1σ. This is the first observation of a C-even state directly produced in e^{+}e^{-} annihilation. The electronic width of the χ_{c1}(1P) resonance is determined to be Γ_{ee}=(0.12_{-0.08}^{+0.13})  eV, which is of the same order of magnitude as theoretical calculations.

Evidence for a Neutral Near-Threshold Structure in the K_{S}^{0} Recoil-Mass Spectra in e^{+}e^{-}→K_{S}^{0}D_{s}^{+}D^{*-} and e^{+}e^{-}→K_{S}^{0}D_{s}^{*+}D^{-}

We study the processes e^{+}e^{-}→K_{S}^{0}D_{s}^{+}D^{*-} and e^{+}e^{-}→K_{S}^{0}D_{s}^{*+}D^{-}, as well as their charge conjugated processes, at five center-of-mass energies between 4.628 and 4.699 GeV, using data samples corresponding to an integrated luminosity of 3.8  fb^{-1} collected by the BESIII detector at the BEPCII storage ring. Based on a partial reconstruction technique, we find evidence of a structure near the thresholds for D_{s}^{+}D^{*-} and D_{s}^{*+}D^{-} production in the K_{S}^{0} recoil-mass spectrum, which we refer to as the Z_{cs}(3985)^{0}. Fitting with a Breit-Wigner line shape, we find the mass of the structure to be (3992.2±1.7±1.6)  MeV/c^{2} and the width to be (7.7_{-3.8}^{+4.1}±4.3)  MeV, where the first uncertainties are statistical and the second are systematic. The significance of the Z_{cs}(3985)^{0} signal is found to be 4.6σ including both the statistical and systematic uncertainty. We report the Born cross section multiplied by the branching fraction at different energy points. The mass of the Z_{cs}(3985)^{0} is close to that of the Z_{cs}(3985)^{+}. Assuming SU(3) symmetry, the cross section of the neutral channel is consistent with that of the charged one. Hence, we conclude that the Z_{cs}(3985)^{0} is the isospin partner of the Z_{cs}(3985)^{+}.

Observation of Resonance Structures in e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) and Mass Measurement of ψ_{2}(3823)

Using a data sample corresponding to an integrated luminosity of 11.3  fb^{-1} collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we measure the product of the e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) cross section and the branching fraction B[ψ_{2}(3823)→γχ_{c1}]. For the first time, resonance structure is observed in the cross section line shape of e^{+}e^{-}→π^{+}π^{-}ψ_{2}(3823) with significances exceeding 5σ. A fit to data with two coherent Breit-Wigner resonances modeling the sqrt[s]-dependent cross section yields M(R_{1})=4406.9±17.2±4.5  MeV/c^{2}, Γ(R_{1})=128.1±37.2±2.3  MeV, and M(R_{2})=4647.9±8.6±0.8  MeV/c^{2}, Γ(R_{2})=33.1±18.6±4.1  MeV. Though weakly disfavored by the data, a single resonance with M(R)=4417.5±26.2±3.5  MeV/c^{2}, Γ(R)=245±48±13  MeV is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the ψ_{2}(3823) state is measured as (3823.12±0.43±0.13)  MeV/c^{2}, which is the most precise measurement to date.

Rational development of mycobacteria cell factory for advancing the steroid biomanufacturing

Steroidal resource occupies a vital proportion in the pharmaceutical industry attributing to their important therapeutic effects on fertility, anti-inflammatory and antiviral activities. Currently, microbial transformation from phytosterol has become the dominant strategy of steroidal drug intermediate synthesis that bypasses the traditional chemical route. Mycobacterium sp. serve as the main industrial microbial strains that are capable of introducing selective functional modifications of steroidal intermediate, which has become an indispensable platform for steroid biomanufacturing. By reviewing the progress in past two decades, the present paper concentrates mainly on the microbial rational modification aspects that include metabolic pathway editing, key enzymes engineering, material transport pathway reinforcement, toxic metabolic intermediates removal and byproduct reconciliation. In addition, progress on omics analysis and direct genetic manipulation are summarized and classified that may help reform the industrial hosts with more efficiency. The paper provides an insightful present for steroid biomanufacturing especially on the current trends and prospects of mycobacteria.

Observation of a State X(2600) in the π^{+}π^{-}η' System in the Process J/ψ→γπ^{+}π^{-}η'

Based on (10087±44)×10^{6}  J/ψ events collected with the BESIII detector, the process J/ψ→γπ^{+}π^{-}η^{'} is studied using two largest decay channels of the η^{'} meson, η^{'}→γπ^{+}π^{-} and η^{'}→ηπ^{+}π^{-}, η→γγ. A new resonance, which we denote as the X(2600), is observed with a statistical significance larger than 20σ in the π^{+}π^{-}η^{'} invariant mass spectrum, and it has a connection to a structure around 1.5  GeV/c^{2} in the π^{+}π^{-} invariant mass spectrum. A simultaneous fit on the π^{+}π^{-}η^{'} and π^{+}π^{-} invariant mass spectra with the two η^{'} decay modes indicates that the mass and width of the X(2600) state are 2618.3±2.0_{-1.4}^{+16.3}  MeV/c^{2} and 195±5_{-17}^{+26}  MeV, where the first uncertainties are statistical, and the second systematic.

Observation of J/ψ Electromagnetic Dalitz Decays to X(1835), X(2120), and X(2370)

Using a sample of about 10^{10}  J/ψ events collected at a center-of-mass energy sqrt[s]=3.097  GeV with the BESIII detector, the electromagnetic Dalitz decays J/ψ→e^{+}e^{-}π^{+}π^{-}η^{'}, with η^{'}→γπ^{+}π^{-} and η^{'}→π^{+}π^{-}η, have been studied. The decay J/ψ→e^{+}e^{-}X(1835) is observed with a significance of 15σ, and also an e^{+}e^{-} invariant-mass dependent transition form factor of J/ψ→e^{+}e^{-}X(1835) is presented for the first time. The intermediate states X(2120) and X(2370) are also observed in the π^{+}π^{-}η^{'} invariant-mass spectrum with significances of 5.3σ and 7.3σ. The corresponding product branching fractions for J/ψ→e^{+}e^{-}X, X→π^{+}π^{-}η^{'} [X=X(1835), X(2120), and X(2370)] are reported.

[Clinical and genetic characteristics of congenital isolated adrenocorticotropic hormone deficiency]

Objective: To investigate the clinical and genetic characteristics of congenital isolated adrenocorticotropic hormone (ACTH) deficiency. Methods: The clinical and laboratory characteristics of 5 cases with congenital isolated ACTH deficiency diagnosed in the Department of Endocrinology of the Children's Hospital, Capital Institute of Pediatrics from January 2019 to March 2021 were retrospectively analyzed. The general conditions, clinical manifestations, laboratory examinations, genetic charcteistics, treatment and follow-up (up to October 2021) were analyzed. Results: Of the 5 cases, 1 was female and 4 were males, aged from 13 months to 6 years at the time of consultation. The symptoms of hypoglycemia and convulsion were presented in infancy, and 4 cases had infantile cholestasis. Glucose level of 5 cases ranged from 0.79-2.20 mmol/L, ACTH ranged from <1.00-4.17 ng/L, and cortisol ranged from 0.2-3.8 μg/L. Whole exon sequencing revealed that 3 cases carried homozygous TBX19 variations, and 2 cases had compound heterozygous TBX19 variations, including 3 variants that had been reported before and 3 novel variants were found. After the diagnosis was confirmed, all the cases were treated with hydrocortisone. Hypoglycemia was all corrected during the follow-up, and 4 cases no longer had convulsions. Conclusion: Congenital isolated ACTH deficiency should be considered in neonates and infants with cholestasis and hypoglycemia, and the diagnosis can be confirmed by genetic testing.

Rerouting Fluxes of the Central Carbon Metabolism and Relieving Mechanism-Based Inactivation of l-Aspartate-α-decarboxylase for Fermentative Production of β-Alanine in Escherichia coli

β-Alanine, with the amino group at the β-position, is an important platform chemical that has been widely applied in pharmaceuticals and feed and food additives. However, the current modest titer and productivity, increased fermentation cost, and complicated operation are the challenges for producing β-alanine by microbial fermentation. In this study, a high-yield β-alanine-producing strain was constructed by combining metabolic engineering, protein engineering, and fed-batch bioprocess optimization strategies. First, an aspartate-α-decarboxylase from Bacillus subtilis was introduced in Escherichia coli W3110 to construct an initial β-alanine-producing strain. Production of β-alanine was obviously increased to 4.36 g/L via improving the metabolic flux and reducing carbon loss by rerouting fluxes of the central carbon metabolism. To further increase β-alanine production, mechanism-based inactivation of aspartate-α-decarboxylase was relieved by rational design to maintain the productivity at a high level in β-alanine fed-batch fermentation. Finally, fed-batch bioprocess optimization strategies were used to improve β-alanine production to 85.18 g/L with 0.24 g/g glucose yield and 1.05 g/L/h productivity in fed-batch fermentation. These strategies can be effectively used in the construction of engineered strains for β-alanine and production of its derivatives, and the final engineered strain was a valuable microbial cell factory that can be used for the industrial production of β-alanine.

[Analysis on psychoactive substances use in men who have sex with men in Tianjin]

Objective: To understand the use of psychoactive substances and its related factors in men who have sex with men (MSM) in Tianjin. Methods: A cross-sectional survey was conducted in MSM recruited in Tianjin by snowball sampling from September 2017 to December 2020, the information about their social demographic information, use of psychoactive substances and behavioral characteristics were collected, meanwhile the blood samples were taken from them for HIV/syphilis detections. Multivariate logistic regression was used to explore related factors about psychoactive substances use. Results: A total of 9 218 MSM were included in the study, in whom 43.5% (4 013/9 218) had ever used psychoactive substances, including 92.6% (3 718/4 013)who used Rush and 17.2% (692/4 013) who used multi substances. Multivariate analysis showed that, the OR of psychoactive substances use in MSM who were in Han ethnic group was 0.68 (95%CI:0.51-0.91) compared with those who were in minor ethnic group; the OR of psychoactive substances use in MSM who were married or cohabited, divorced or widowed were 0.65 (95%CI: 0.57-0.71), 0.80 (95%CI: 0.65-0.97) respectively compared with those who were unmarried; the OR of psychoactive substances use in MSM who had the first homosexual sex at age of ≥30 years was 0.57 (95%CI: 0.44-0.74) compared with those who had the first homosexual sex at age of <30 years; the OR of psychoactive substances use in local MSM in Tianjin was 1.12 (95%CI: 1.03-1.23) compared with those who were not local residents in Tianjin; the OR of psychoactive substances use in MSM with education level of college or above was 1.29 (95%CI: 1.12-1.49) compared with those with education level of junior middle school or below; the OR of psychoactive substances use in MSM who had anal sex in the past six months was 1.93 (95%CI: 1.34-2.77) compared with those who had no anal sex; the OR of psychoactive substances use in MSM who had >2 homosexual partners in the last week was 1.62 (95%CI: 1.41-1.87) compared with those who had ≤2 homosexual partners; the OR of psychoactive substances use in MSM who had homosexual commercial sex in the past six months was 1.99 (95%CI: 1.62-2.45) compared with those who had no homosexual commercial sex; the OR of psychoactive substances use in MSM who had sexually transmitted diseases in the last year was 2.39 (95%CI: 1.82-3.12) compared with those who had no sexually transmitted diseases and the OR of psychoactive substances use in MSM who received peer education services in the last year was 1.63 (95%CI: 1.50-1.78) compared with those who received no peer education services. Conclusion: The prevalence of psychoactive substances use is high in MSM in Tianjin, and there are many influencing factors. It is necessary to conduct targeted interventions according to the influencing factors.

Module engineering coupled with omics strategies for enhancing D-pantothenate production in Escherichia coli

Biosynthesis of D-pantothenate has been widely studied as D-pantothenate is one kind of important vitamins used in food and pharmaceuticals. However, the engineered strain for D-pantothenate production was focused solely on the main biosynthetic pathway, while other important factors such as one carbon unit were ignored. Here the systematic modular engineering on different factors coupled with omics analysis were studied in Escherichia coli for efficient D-pantothenate production. Through reinforcing the precursor pool, refactoring the one carbon unit generation pathway, optimization of reducing power and energy supply, the D-pantothenate titer reached 34.12 g/L with the yield at 0.28 g/g glucose under fed-batch fermentation in 5-L bioreactor. With a further comparative transcriptome and metabolomics studies, the addition of citrate was implemented and 45.35 g/L D-pantothenate was accumulated with a yield of 0.31 g/g glucose. The systematic modular engineering coupled with omics studies provide useful strategies for the industrial production of D-pantothenate.

Two-Photon Excited Fluorescent 3,3'-Diamino-5,5'-Diboryl-2,2'-Bithienyls Featuring a Quadrupolar Structure

The quest for fluorophores exhibiting large two-photon absorption cross sections and high fluorescence efficiency is an important topic. Two 2,2'-bithienyl derivatives are disclosed which contain two N,N-disubstituted amino and two dimesitylboryl groups at 3,3'- and 5,5'-positions, respectively. Despite the great steric effect of amino groups, the bithienyl skeleton still adopts a coplanar geometry. Herein, they are characterized by a quadrupolar structure and display good fluorescence efficiency and large two-photon absorption cross sections up to 473 GM.