Observation of Structures in the Processes e

We present measurements of the Born cross sections for the processes e^{+}e^{-}→ωχ_{c1} and ωχ_{c2} at center-of-mass energies sqrt[s] from 4.308 to 4.951 GeV. The measurements are performed with data samples corresponding to an integrated luminosity of 11.0 fb^{-1} collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring. Assuming the e^{+}e^{-}→ωχ_{c2} signals come from a single resonance, the mass and width are determined to be M=(4413.6±9.0±0.8) MeV/c^{2} and Γ=(110.5±15.0±2.9) MeV, respectively, which is consistent with the parameters of the well-established resonance ψ(4415). In addition, we also use one single resonance to describe the e^{+}e^{-}→ωχ_{c1} line shape and determine the mass and width to be M=(4544.2±18.7±1.7) MeV/c^{2} and Γ=(116.1±33.5±1.7) MeV, respectively. The structure of this line shape, observed for the first time, requires further understanding.

Determination of Spin-Parity Quantum Numbers of X(2370) as 0

Based on (10087±44)×10^{6} J/ψ events collected with the BESIII detector, a partial wave analysis of the decay J/ψ→γK_{S}^{0}K_{S}^{0}η^{'} is performed. The mass and width of the X(2370) are measured to be 2395±11(stat)_{-94}^{+26}(syst) MeV/c^{2} and 188_{-17}^{+18}(stat)_{-33}^{+124}(syst) MeV, respectively. The corresponding product branching fraction is B[J/ψ→γX(2370)]×B[X(2370)→f_{0}(980)η^{'}]×B[f_{0}(980)→K_{S}^{0}K_{S}^{0}]=(1.31±0.22(stat)_{-0.84}^{+2.85}(syst))×10^{-5}. The statistical significance of the X(2370) is greater than 11.7σ and the spin parity is determined to be 0^{-+} for the first time. The measured mass and spin parity of the X(2370) are consistent with the predictions of the lightest pseudoscalar glueball.

Observation of Significant Flavor-SU(3) Breaking in the Kaon Wave Function at 12

We present cross sections for the reaction e^{+}e^{-}→K_{S}^{0}K_{L}^{0} at center-of-mass energies ranging from 3.51 to 4.95 GeV using data samples collected in the BESIII experiment, corresponding to a total integrated luminosity of 26.5 fb^{-1}. The ratio of neutral-to-charged kaon form factors at large momentum transfers (12

Observation of D

We perform for the first time an amplitude analysis of the decay D^{+}→K_{S}^{0}π^{+}η and report the observation of the decay D^{+}→K_{S}^{0}a_{0}(980)^{+} using 2.93 fb^{-1} of e^{+}e^{-} collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. As the only W-annihilation-free decay among D to a_{0}(980) pseudoscalar, D^{+}→K_{S}^{0}a_{0}(980)^{+} is the ideal decay in extracting the contributions of the W-emission amplitudes involving a_{0}(980) and to study the final-state interactions. The absolute branching fraction of D^{+}→K_{S}^{0}π^{+}η is measured to be (1.27±0.04_{stat}±0.03_{syst})%. The branching fractions of intermediate processes D^{+}→K_{S}^{0}a_{0}(980)^{+} with a_{0}(980)^{+}→π^{+}η and D^{+}→π^{+}K[over ¯]_{0}^{*}(1430)^{0} with K[over ¯]_{0}^{*}(1430)^{0}→K_{S}^{0}η are measured to be (1.33±0.05_{stat}±0.04_{syst})% and (0.14±0.03_{stat}±0.01_{syst})%, respectively.

Study of the f_{0}(980) and f_{0}(500) Scalar Mesons through the Decay D_{s}

Using e^{+}e^{-} collision data corresponding to an integrated luminosity of 7.33 fb^{-1} recorded by the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, we present an analysis of the decay D_{s}^{+}→π^{+}π^{-}e^{+}ν_{e}, where the D_{s}^{+} is produced via the process e^{+}e^{-}→D_{s}^{*±}D_{s}^{∓}. We observe the f_{0}(980) in the π^{+}π^{-} system and the branching fraction of the decay D_{s}^{+}→f_{0}(980)e^{+}ν_{e} with f_{0}(980)→π^{+}π^{-} measured to be (1.72±0.13_{stat}±0.10_{syst})×10^{-3}, where the uncertainties are statistical and systematic, respectively. The dynamics of the D_{s}^{+}→f_{0}(980)e^{+}ν_{e} decay are studied with the simple pole parametrization of the hadronic form factor and the Flatté formula describing the f_{0}(980) in the differential decay rate, and the product of the form factor f_{+}^{f_{0}}(0) and the c→s Cabibbo-Kobayashi-Maskawa matrix element |V_{cs}| is determined for the first time to be f_{+}^{f_{0}}(0)|V_{cs}|=0.504±0.017_{stat}±0.035_{syst}. Furthermore, the decay D_{s}^{+}→f_{0}(500)e^{+}ν_{e} is searched for the first time but no signal is found. The upper limit on the branching fraction of D_{s}^{+}→f_{0}(500)e^{+}ν_{e}, f_{0}(500)→π^{+}π^{-} decay is set to be 3.3×10^{-4} at 90% confidence level.

Coupled-Channel Analysis of the χ_{c1}(3872) Line Shape with BESIII Data.

We perform a study of the χ_{c1}(3872) line shape using the data samples of e^{+}e^{-}→γχ_{c1}(3872), χ_{c1}(3872)→D^{0}D[over ¯]^{0}π^{0}, and π^{+}π^{-}J/ψ collected with the BESIII detector. The effects of the coupled channels and the off-shell D^{*0} are included in the parametrization of the line shape. The line shape mass parameter is obtained to be M_{X}=(3871.63±0.13_{-0.05}^{+0.06}) MeV. Two poles are found on the first and second Riemann sheets corresponding to the D^{*0}D[over ¯]^{0} branch cut. The pole location on the first sheet is much closer to the D^{*0}D[over ¯]^{0} threshold than the other, and is determined to be 7.04±0.15_{-0.08}^{+0.07} MeV above the D^{0}D[over ¯]^{0}π^{0} threshold with an imaginary part -0.19±0.08_{-0.19}^{+0.14} MeV.

Observation of the Anomalous Shape of X(1840) in J/ψ→γ3(π

Using a sample of (10087±44)×10^{6} J/ψ events, which is about 45 times larger than that was previously analyzed, a further investigation on the J/ψ→γ3(π^{+}π^{-}) decay is performed. A significant distortion at 1.84 GeV/c^{2} in the line shape of the 3(π^{+}π^{-}) invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, X(1840) and X(1880). The new state X(1880) is observed with a statistical significance larger than 10σ. The mass and width of X(1880) are determined to be 1882.1±1.7±0.7 MeV/c^{2} and 30.7±5.5±2.4 MeV, respectively, which indicates the existence of a pp[over ¯] bound state.

[Effects of early debridement and conservative eschar removal followed by wound coverage with acellular dermal matrix in the treatment of children with deep burns].

Objective: To explore the effects of early debridement and conservative eschar removal followed by wound coverage with acellular dermal matrix (ADM), i.e., early surgery, in the treatment of children with deep burns. Methods: This study was a retrospective cohort study. From January 2017 to December 2022, 278 deep burned hospitalized children aged 1-7 years who met the inclusion criteria were admitted to Central Hospital Affiliated to Shandong First Medical University. According to the differences in treatment processes, 134 children who underwent early surgery+routine dressing change were enrolled in eschar removal+dressing change group (77 males and 57 females, aged 1 (1, 2) years), and 144 children who underwent only routine dressing change were enrolled in dressing change alone group (90 males and 54 females, aged 1 (1, 2) years). Fifty-one children without full-thickness burns in eschar removal+dressing change group were enrolled in eschar removal+dressing change group 1 (26 males and 25 females, aged 1 (1, 2) years), and 57 cases of the 83 children with full-thickness burns who did not undergo autologous skin grafting at the same time of early surgery (namely early skin grafting) in eschar removal+dressing change group were included in eschar removal+dressing change group 2 (37 males and 20 females, aged 1 (1, 2) years). Seventy-six children without full-thickness burns in dressing change alone group were included in dressing change alone group 1 (51 males and 25 females, aged 1 (1, 3) years), and 68 children with full-thickness burns in dressing change alone group were included in dressing change alone group 2 (39 males and 29 females, aged 1 (1, 2) years). For deep partial-thickness burn wounds and small full-thickness burn wounds in eschar removal+dressing change group, the eschar removal was performed on the basis of retaining a thin layer of denatured dermis so as to preserve the healthy tissue of the wound base, and ADM was applied to all wounds externally after eschar removal. For larger full-thickness burn wounds in this group, especially those located in the functional part of joints, eschar removal to the plane layer of viable tissue and early autologous skin grafting was needed. When the superficial wounds of children healed or tended to heal, the residual wounds were evaluated, and elective autologous skin grafting was performed if it was difficult to heal within 14 days. The healing time, intervention healing time, times of operation/dressing change, and times of intervention operation/dressing change in children with deep partial-thickness burn wounds of children in eschar removal+dressing change group, dressing change alone group, eschar removal+dressing change group 1, and dressing change alone group 1 were recorded. At the last follow-up (follow-up period was set to 7-12 months), the modified Vancouver scar scale (mVSS) scores of the most severe area of scar hyperplasia of healed deep partial-thickness burn wounds of 54 children in eschar removal+dressing change group and 48 children in dressing change alone group were recorded. The healing time and times of operation/dressing change of all burn wounds of children in eschar removal+dressing change group and dressing change alone group, and the healing time and times of operation/dressing change of full-thickness burn wounds of children in eschar removal+dressing change group 2 and dressing change alone group 2 were recorded. The incidences of wound infection, sepsis, fever, and fever after 5 days of burns in children of eschar removal+dressing change group and dressing change alone group during wound healing. Results: Compared with those in dressing change alone group, the healing time and intervention healing time were significantly shortened, and the times of operation/dressing change and times of intervention operation/dressing change were significantly reduced in children with deep partial-thickness burn wounds in eschar removal+dressing change group (with Z values of -11.00, -11.33, -12.64, and -11.65, respectively, P<0.05). Compared with those in dressing change alone group 1, the healing time and intervention healing time were significantly shortened, and the times of operation/dressing change and times of intervention operation/dressing change were significantly reduced in children with deep partial-thickness burn wounds in eschar removal+dressing change group 1 (with Z values of 6.57, 6.46, 8.04, and 6.57, respectively, P<0.05). At the last follow-up, the mVSS score of the most severe scar hyperplasia area of healed deep partial-thickness burn wounds of 54 children in eschar removal+dressing change group was 4.00 (3.00,5.00), which was significantly lower than 6.50 (5.00,7.00) of 48 children in dressing change alone group (Z =-4.67, P<0.05).Compared with those in dressing change alone group, the healing time was significantly shortened, and times of operation/dressing change was significantly reduced in all burn wounds in eschar removal+dressing change group (with Z values of -5.20 and -6.34, respectively, P<0.05). Compared with those in dressing change alone group 2, the healing time was significantly shortened, and times of operation/dressing change was significantly reduced in full-thickness burn wounds in eschar removal+dressing change group 2 (with Z values of -5.22 and -5.73, respectively, P<0.05). During wound healing, the probabilities of fever and fever after 5 days of burns in children of eschar removal+dressing change group were significantly lower than those in dressing change alone group (with χ2 values of 4.13 and 3.91, respectively, P<0.05); only 1 child in dressing change alone group developed sepsis, and there was no statistically significant difference in the wound infection rate of children in the two groups (P>0.05). Conclusions: For children with deep burns, early surgery, and early skin grafting or elective autologous skin grafting as needed, have better short-term and long-term effects than those without early surgery.

Determination of the Σ

Based on data samples collected with the BESIII detector at the BEPCII collider, the process e^{+}e^{-}→Σ^{+}Σ[over ¯]^{-} is studied at center-of-mass energies sqrt[s]=2.3960, 2.6454, and 2.9000 GeV. Using a fully differential angular description of the final state particles, both the relative magnitude and phase information of the Σ^{+} electromagnetic form factors in the timelike region are extracted. The relative phase between the electric and magnetic form factors is determined to be sinΔΦ=-0.67±0.29(stat)±0.18(syst) at sqrt[s]=2.3960 GeV, ΔΦ=55°±19°(stat)±14°(syst) at sqrt[s]=2.6454 GeV, and 78°±22°(stat)±9°(syst) at sqrt[s]=2.9000 GeV. For the first time, the phase of the hyperon electromagnetic form factors is explored in a wide range of four-momentum transfer. The evolution of the phase along with four-momentum transfer is an important input for understanding its asymptotic behavior and the dynamics of baryons.

Investigation of the ΔI=1/2 Rule and Test of CP Symmetry through the Measurement of Decay Asymmetry Parameters in Ξ

Using (10087±44)×10^{6} J/ψ events collected with the BESIII detector, numerous Ξ^{-} and Λ decay asymmetry parameters are simultaneously determined from the process J/ψ→Ξ^{-}Ξ[over ¯]^{+}→Λ(pπ^{-})π^{-}Λ[over ¯](n[over ¯]π^{0})π^{+} and its charge-conjugate channel. The precisions of α_{Λ0} for Λ→nπ^{0} and α[over ¯]_{Λ0} for Λ[over ¯]→n[over ¯]π^{0} compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of Λ→nπ^{0} to that of Λ→pπ^{-}, ⟨α_{Λ0}⟩/⟨α_{Λ-}⟩, is determined to be 0.873±0.012_{-0.010}^{+0.011}, where the first and the second uncertainties are statistical and systematic, respectively. The ratio is smaller than unity more than 5σ, which signifies the existence of the ΔI=3/2 transition in Λ for the first time. Besides, we test for CP symmetry in Ξ^{-}→Λπ^{-} and in Λ→nπ^{0} with the best precision to date.

Observation of D_{s}

By analyzing 7.33 fb^{-1} of e^{+}e^{-} annihilation data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we report the observation of the semileptonic decay D_{s}^{+}→η^{'}µ^{+}ν_{µ}, with a statistical significance larger than 10σ, and the measurements of the D_{s}^{+}→ηµ^{+}ν_{µ} and D_{s}^{+}→η^{'}µ^{+}ν_{µ} decay dynamics for the first time. The branching fractions of D_{s}^{+}→ηµ^{+}ν_{µ} and D_{s}^{+}→η^{'}µ^{+}ν_{µ} are determined to be (2.235±0.051_{stat}±0.052_{syst})% and (0.801±0.055_{stat}±0.028_{syst})%, respectively, with precision improved by factors of 6.0 and 6.6 compared to the previous best measurements. Combined with the results for the decays D_{s}^{+}→ηe^{+}ν_{e} and D_{s}^{+}→η^{'}e^{+}ν_{e}, the ratios of the decay widths are examined both inclusively and in several ℓ^{+}ν_{ℓ} four-momentum transfer ranges. No evidence for lepton flavor universality violation is found within the current statistics. The products of the hadronic form factors f_{+,0}^{η^{(')}}(0) and the c→s Cabibbo-Kobayashi-Maskawa matrix element |V_{cs}| are determined. The results based on the two-parameter series expansion are f_{+,0}^{η}(0)|V_{cs}|=0.452±0.010_{stat}±0.007_{syst} and f_{+,0}^{η^{'}}(0)|V_{cs}|=0.504±0.037_{stat}±0.012_{syst}, which help to constrain present models on f_{+,0}^{η^{(')}}(0). The forward-backward asymmetries are determined to be ⟨A_{FB}^{η}⟩=-0.059±0.031_{stat}±0.005_{syst} and ⟨A_{FB}^{η^{'}}⟩=-0.064±0.079_{stat}±0.006_{syst} for the first time, which are consistent with the theoretical calculation.

First Measurement of the Decay Asymmetry in the Pure W-Boson-Exchange Decay Λ_{c}

Based on 4.4 fb^{-1} of e^{+}e^{-} annihilation data collected at the center-of-mass energies between 4.60 and 4.70 GeV with the BESIII detector at the BEPCII collider, the pure W-boson-exchange decay Λ_{c}^{+}→Ξ^{0}K^{+} is studied with a full angular analysis. The corresponding decay asymmetry is measured for the first time to be α_{Ξ^{0}K^{+}}=0.01±0.16(stat)±0.03(syst). This result reflects the noninterference effect between the S- and P-wave amplitudes. The phase shift between S- and P-wave amplitudes has two solutions, which are δ_{p}-δ_{s}=-1.55±0.25(stat)±0.05(syst) rad or 1.59±0.25(stat)±0.05(syst) rad.

[Research on the framework of biosafety standards for pathogenic microbial laboratories].

Developing and implementing biosafety standards for pathogenic microbiology laboratories is essential to achieving scientific, efficient, and standardized management and operation. This article analyzes the current standardization construction in biosafety in pathogenic microbiology laboratories domestically and internationally. It proposes a framework for the biosafety standard system of pathogenic microbiology laboratories, which mainly includes four parts: basic standards, management standards, technical standards, and industry applications. It provides a reference for the standardization work of pathogenic microbiology laboratories and helps to standardize the biosafety industry in China.

Observation of a Vector Charmoniumlike State at 4.7 GeV/c

Using data samples with an integrated luminosity of 5.85 fb^{-1} collected at center-of-mass energies from 4.61 to 4.95 GeV with the BESIII detector operating at the BEPCII storage ring, we measure the cross section for the process e^{+}e^{-}→K^{+}K^{-}J/ψ. A new resonance with a mass of M=4708_{-15}^{+17}±21 MeV/c^{2} and a width of Γ=126_{-23}^{+27}±30 MeV is observed in the energy-dependent line shape of the e^{+}e^{-}→K^{+}K^{-}J/ψ cross section with a significance over 5σ. The K^{+}J/ψ system is also investigated to search for charged charmoniumlike states, but no significant Z_{cs}^{+} states are observed. Upper limits on the Born cross sections for e^{+}e^{-}→K^{-}Z_{cs}(3985)^{+}/K^{-}Z_{cs}(4000)^{+}+c.c. with Z_{cs}(3985)^{±}/Z_{cs}(4000)^{±}→K^{±}J/ψ are reported at 90% confidence levels. The ratio of branching fractions {[B(Z_{cs}(3985)^{+}→K^{+}J/ψ)]/B[Z_{cs}(3985)^{+}→(D[over ¯]^{0}D_{s}^{*+}+D[over ¯]^{*0}D_{s}^{+})]} is measured to be less than 0.03 at 90% confidence level.

Measurement of Energy-Dependent Pair-Production Cross Section and Electromagnetic Form Factors of a Charmed Baryon.

We study the process e^{+}e^{-}→Λ_{c}^{+}Λ[over ¯]_{c}^{-} at twelve center-of-mass energies from 4.6119 to 4.9509 GeV using data samples collected by the BESIII detector at the BEPCII collider. The Born cross sections and effective form factors (|G_{eff}|) are determined with unprecedented precision after combining the single and double-tag methods based on the decay process Λ_{c}^{+}→pK^{-}π^{+}. Flat cross sections around 4.63 GeV are obtained and no indication of the resonant structure Y(4630), as reported by Belle, is found. In addition, no oscillatory behavior is discerned in the |G_{eff}| energy dependence of Λ_{c}^{+}, in contrast to what is seen for the proton and neutron cases. Analyzing the cross section together with the polar-angle distribution of the Λ_{c}^{+} baryon at each energy point, the moduli of electric and magnetic form factors (|G_{E}| and |G_{M}|) are extracted and separated. For the first time, the energy dependence of the form factor ratio |G_{E}/G_{M}| is observed, which can be well described by an oscillatory function.

Test of CP Symmetry in Hyperon to Neutron Decays.

The quantum entangled J/ψ→Σ^{+}Σ[over ¯]^{-} pairs from (1.0087±0.0044)×10^{10} J/ψ events taken by the BESIII detector are used to study the nonleptonic two-body weak decays Σ^{+}→nπ^{+} and Σ[over ¯]^{-}→n[over ¯]π^{-}. The CP-odd weak decay parameters of the decays Σ^{+}→nπ^{+} (α_{+}) and Σ[over ¯]^{-}→n[over ¯]π^{-} (α[over ¯]_{-}) are determined to be 0.0481±0.0031_{stat}±0.0019_{syst} and -0.0565±0.0047_{stat}±0.0022_{syst}, respectively. The decay parameter α[over ¯]_{-} is measured for the first time, and the accuracy of α_{+} is improved by a factor of 4 compared to the previous results. The simultaneously determined decay parameters allow the first precision CP symmetry test for any hyperon decay with a neutron in the final state with the measurement of A_{CP}=(α_{+}+α[over ¯]_{-})/(α_{+}-α[over ¯]_{-})=-0.080±0.052_{stat}±0.028_{syst}. Assuming CP conservation, the average decay parameter is determined as ⟨α_{+}⟩=(α_{+}-α[over ¯]_{-})/2=-0.0506±0.0026_{stat}±0.0019_{syst}, while the ratios α_{+}/α_{0} and α[over ¯]_{-}/α[over ¯]_{0} are -0.0490±0.0032_{stat}±0.0021_{syst} and -0.0571±0.0053_{stat}±0.0032_{syst}, where α_{0} and α[over ¯]_{0} are the decay parameters of the decays Σ^{+}→pπ^{0} and Σ[over ¯]^{-}→p[over ¯]π^{0}, respectively.

[Application effects of nitrous oxide and oxygen mixed inhalation technology on analgesia and sedation during debridement and dressing change in children with moderate or severe burns].

Objective: To investigate the application effects of nitrous oxide and oxygen mixed inhalation technology on analgesia and sedation during debridement and dressing change in children with moderate or severe burns. Methods: A retrospective non-randomized contemporary controlled study was conducted. From December 2019 to November 2021, 140 burn children with moderate or severe burns, aged 1 to 3 years, who met the inclusion criteria were admitted to Central Hospital Affiliated to Shandong First Medical University. During debridement and dressing change 3 to 14 days after injury, 42 children, including 23 males and 19 females, who received nurse-centered pain management mode and analgesia and sedation with nitrous oxide and oxygen mixed inhalation technology were included in nitrous oxide group (the dressing change process using the above-mentioned technology for the first time was selected for the follow-up study). Another 42 children, including 24 males and 18 females, were included in non-nitrous oxide group from 98 children who did not apply analgesia or sedation treatment during dressing change with stratified random sampling (one dressing change process was randomly selected for the follow-up study). The face, legs, activity, cry, and consolability scale and Ramsay sedation scale were used to evaluate the pain intensity and degree of sedation, respectively, at 30 minutes before dressing change (hereinafter referred to as before dressing change), immediately after debridement, and at 30 minutes after finishing dressing change (hereinafter referred to as after dressing change). After dressing change, the self-made satisfaction scale was used to evaluate the satisfaction degree of dressing change surgeons and guardians of children for analgesic effects during dressing change. The duration of dressing change and the healing time of deep partial-thickness burn wounds were recorded. The heart rate and percutaneous arterial oxygen saturation (SpO2) before, during, and after dressing change and the occurrence of adverse events such as nausea and vomiting during dressing change were recorded. Data were statistically analyzed with Mann-Whitney U test, chi-square test, analysis of variance for repeated measurement, independent sample t test, and Bonferroni correction. Results: There were no significant differences in the score of pain intensity and score of sedation degree between children in two groups before and after dressing change (P>0.05). Immediately after debridement, the score of pain intensity of children in nitrous oxide group was 2.5±0.7, which was significantly lower than 7.6±1.0 in non-nitrous oxide group (t=-26.69, P<0.05); the score of sedation degree of children in nitrous oxide group was 1.83±0.38, which was significantly higher than 1.21±0.42 in non-nitrous oxide group (t=7.15, P<0.05). After dressing change, the satisfaction degree scores of dressing change surgeons and guardians of children for analgesic effects during dressing change of children in nitrous oxide group were significantly higher than those in non-nitrous oxide group (with t values of 10.53 and 2.24, respectively, P<0.05). The dressing change duration of children in nitrous oxide group was significantly shorter than that in non-nitrous oxide group (t=-5.33, P<0.05). The healing time of deep partial-thickness burn wounds in children between the two groups had no significant difference (P>0.05). The heart rate of children in nitrous oxide group was significantly lower than that in non-nitrous oxide group during dressing change (t=-12.40, P<0.05), while the SpO2 was significantly higher than that in non-nitrous oxide group (t=5.98, P<0.05). During dressing change, 2 children had nausea and 1 child had euphoria in nitrous oxide group, while heart rate of all children in non-nitrous oxide group continued to be higher than the normal range. Conclusions: In the process of debridement and dressing change in children with moderate or severe burns, the use of nurse-centered pain management mode and the standardized use of nitrous oxide and oxygen mixed inhalation technology can safely and effectively control pain and sedation.

[Effects of tensile force on the vascular lumen formation in three-dimensional printed tissue].

Objective: To explore the effects of tensile force on vascular lumen formation in three-dimensional printed tissue. Methods: The experimental research method was used. Human umbilical vein endothelial cells (HUVECs) were extracted from discarded umbilical cord tissue of 3 healthy women (aged 22 to 35 years) who gave birth in the Department of Gynaecology and Obstetrics of Suzhou Ruihua Orthopaedic Hospital from September 2020 to May 2021. Human skin fibroblasts (HSFs) were extracted from discarded normal skin tissue of 10 male patients (aged 20 to 45 years) who underwent wound repair in the Department of Hand Surgery of Suzhou Ruihua Orthopaedic Hospital from September 2020 to September 2022. After identification of the two kinds of cells, the 4th to 6th passage of cells were taken for the follow-up experiments. HUVECs and HSFs were used as seed cells, and polycaprolactone, gelatin, hyaluronic acid, and fibrin were used as scaffold materials, and the three-dimensional printed vascularized tissue was created by three-dimensional bioprinting technology. The printed tissue with polycaprolactone scaffold of 6 and 10 mm spacing, and without polycaprolactone scaffold were set as 6 mm spacing polycaprolactone group, 10 mm spacing polycaprolactone group, and non-polycaprolactone group, respectively. After 4 days of culture, the printed tissue in 10 mm spacing polycaprolactone group was selected to detect the cell survival by cell viability detection kit, and the cell survival rate was calculated. After 14 days of culture, the printed tissue in three groups were taken, and the shape change of tissue was observed by naked eyes; immunofluorescence staining was performed to observe the arrangement of filamentous actin, and lumen diameter, total length, and number of branches of vessel in the tissue. The tissue with micro-spring structure in the above-mentioned three groups was designed, printed, and cultured for 9 days, and the tensile force applied in the printed tissue was measured according to the force-displacement curve. The number of samples was all 3 in the above experiments. Data were statistically analyzed with one-way analysis of variance and Tukey test. Results: After 4 days of culture, the cell survival rate in printed tissue in 10 mm spacing polycaprolactone group was (91.3±2.2)%. After 14 days of culture, the shape change of printed tissue in non-polycaprolactone group was not obvious, while the shape changes of printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were obvious. After 14 days of culture, the arrangement of filamentous actin in the printed tissue in non-polycaprolactone group had no specific direction, while the arrangement of filamentous actin in the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group had a specific direction. After 14 days of culture, The vascular lumen diameters of the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were (6.0±1.3) and (10.8±1.3) µm, respectively, which were significantly larger than 0 µm in non-polycaprolactone group (P<0.05), and the vascular lumen diameter of printed tissue in 10 mm spacing polycaprolactone group was significantly larger than that in 6 mm spacing polycaprolactone group (P<0.05); the total length and number of branches of blood vessel in the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were significantly shorter or less than those in non-polycaprolactone group (P<0.05), and the total length and number of branches of blood vessel in the printed tissue in 10 mm spacing polycaprolactone group were significantly shorter or less than those in 6 mm spacing polycaprolactone group. After 9 days of culture, the tensile forces applied in the printed tissue in 6 mm spacing polycaprolactone group and 10 mm spacing polycaprolactone group were (2 340±59) and (4 284±538) µN, respectively, which were significantly higher than 0 µN in non-polycaprolactone group (P<0.05), and the tensile force applied in the printed tissue in 10 mm spacing polycaprolactone group was significantly higher than that in 6 mm spacing polycaprolactone group (P<0.05). Conclusions: The three-dimensional printed scaffold structure can exert different tensile force in the printed tissue, and the vascular lumen diameter of the printed tissue can be regulated by adjusting the tensile force.

[Clinical effects of free perforator propeller myocutaneous flap from buttock in repairing complex wounds in the buttock with deep dead cavity].

Objective: To investigate the feasibility and clinical effects of using free perforator propeller myocutaneous flap from buttock in repairing complex wounds in the buttock with deep dead cavity. Methods: A retrospective observational study was conducted. From June 2020 to June 2022, 9 patients with complex wounds in the buttock with deep dead cavity who met the inclusion criteria were admitted to Lanzhou University Second Hospital, including 6 males and 3 females, aged 26 to 62 years, with original wound area ranging from 4.0 cm×3.0 cm to 8.0 cm×7.0 cm and dead cavity depth of 7 to 11 cm. All the wounds were repaired with free perforator propeller myocutaneous flap from buttock, with flap area of 6.0 cm×2.5 cm to 13.0 cm×7.0 cm and muscle flap length of 6 to 11 cm. All the wounds in the donor area were closed and sutured directly. Postoperative myocutaneous flap survival, complications, as well as donor and recipient wound healing were observed, and the shape of donor and recipient areas were followed up. Results: Congestion occurred under the myocutaneous flap of one patient due to poor drainage on post surgery day 2, which was healed after 15 days of drainage and dressing change. The myocutaneous flaps of other patients survived successfully after surgery. The wounds in the donor and recipient areas were all well healed. During the follow-up of 3 to 10 months, the donor and recipient areas were full in shape, with little difference from the healthy side, and were able to bear pressure. Conclusions: The free perforator propeller myocutaneous flap from buttock can repair the deep dead cavity and surface wounds at the same time. The use of this myocutaneous flap in repairing complex wounds in the buttock with deep dead cavity results in minimal damage to the donor area, allows pressure-bearing of the donor and recipient areas after surgery, and ensures a full buttock shape.