Design, Synthesis, Antitumor Activity Evaluation, and Molecular Dynamics Simulation of Some 2-Aminopyrazine Derivatives.

OBJECTIVE: Cancer poses a great threat to human health, and effective drugs to treat it are always needed. Several compounds containing a 2-aminopyrazine framework have been identified as antitumor agents with SHP2 inhibition activities. This current work aimed to search for more potent novel compounds possessing a 2-aminopyrazine moiety with antitumor activities. METHODS: A series of 12 novel 2-aminopyrazine derivatives was synthesized, and their structures were confirmed by spectroscopic techniques. The inhibitory activities of all the synthesized compounds against MDA-MB-231 and H1975 cancer cell lines were evaluated by an MTT assay. The most potent compound 3e was analyzed by flow cytometry. Subsequently, computational studies were performed to investigate the possible antitumor mechanisms of compound 3e. RESULTS: The results indicated that compound 3e exhibited potent antitumor activities with IC50 values of 11.84±0.83µM against H1975 cells and 5.66±2.39µM against MDA-MB-231 cells, which were more potent than the SHP2 inhibitor GS493 (IC50 = 19.08±1.01 µM against H1975 cells and IC50 = 25.02±1.47 µM against MDA-MB-231 cells). Further analysis by flow cytometry demonstrated that compound 3e induced cell apoptosis in H1975 cells. The results of the molecular docking and MD simulations, including RMSD, RMSF, PCA, DCCM and binding energy and decomposition analyses, revealed that compound 3e probably selectively inhibited SHP2. CONCLUSION: A new compound having a 2-aminopyrazine substructure with potent inhibitory activities against the H1975 and MDA-MB-231 cancer cells was obtained, meriting further investigation as an antitumor drug.

Experience with the management of 2599 cases of congenital muscular torticollis and a multicenter epidemiological investigation in 17 hospitals in China.

BACKGROUND: Congenital muscular torticollis (CMT) is a common musculoskeletal disease affecting infants and young children. If CMT is not treated correctly and timely, it can lead to limited head and neck movements, head and neck deviation, and abnormal posture. In order to improve patients' symptoms and alleviate the negative impact of the disease on their lives, we are committed to exploring the treatment of CMT. METHODS: The general clinical and ultrasonographic data of 2599 children with CMT who received standardized treatment at Shenzhen Children's Hospital from 2004 to 2020 were retrospectively reviewed. According to given treatment, children with CMT were divided into the physiotherapy group, physiotherapy combined with glucocorticoid treatment group, and surgical treatment group. We divided children with CMT into local mass, uniform thickening, and atrophy according to ultrasound features. General clinical information, treatment, and ultrasound examination data in each group were compared. Additionally, electronic medical records of 2344 patients admitted due to CMT in 17 tertiary children's hospitals of China's Futang Research Center of Pediatric Development (FRCPD) from 2015 to 2019 were retrospectively analyzed. Data on sex, age, year of admission and discharge, and treatment costs during hospitalization were extracted from the first medical record pages according to the ICD codes. The data were assessed for normality using the Kolmogorov-Smirnov test. Depending on the data distribution, they were analyzed using parametric tests, such as the t-test, or non-parametric tests. Qualitative data are expressed as percentages (%) and analyzed using the chi-square or Fisher's exact probability test, with α = 0.05 as the test level. P < 0.05 was considered to be indicative of a statistically significant difference. RESULTS: Three types of CMT were defined based on sternocleidomastoid muscle ultrasound examination characteristics: local mass, uniform thickening, and atrophy. Age at first diagnosis was 69.21 ± 108.41 days in local mass type group, 216.85 ± 324.09 days in uniform thickening group, and 417.88 ± 739.05 days in atrophy- type group; while age at first physiotherapy use was 94.06 ± 206.49 days, 255.00 ± 430.62 days, 540.92 ± 1059.29 respectively. The children included in local mass type group have shown a high success rate of conservative treatment, with a rate of 7.5% of children underwent surgery. Age at first diagnosis was 112.44 ± 224.12 days in the physiotherapy group, 115.87 ± 144.86 days in the physiotherapy combined with glucocorticoid treatment subgroup, whereas the age at first physiotherapy use was 137.38 ± 312.11 and 196.91 ± 344.26 days respectively. In the observation period (2015-2019) the mean age at surgery for CMT in 17 tertiary children's hospitals of the FRCPD was 50 months. Overall, 663 children with CMT were 1-2 years of age, accounting for the largest proportion (28.3%). Followed by 417 individuals (17.8%) were 7-14 years of age, indicating that there are still more children with CMT receiving surgical treatment later. CONCLUSIONS: Early diagnosis and treatment are essential to improve the conservative treatment success rate and achieve good prognosis in children with CMT. Our team's concept for treating CMT is as follows: after diagnosing the children, we will adopt the standardized protocol of treatment, with physiotherapy combined with the injection of glucocorticoid drugs and SCM release surgery, when needed. This program has a high conservative treatment success rate and may facilitate the achievement of better prognosis and reduced teratogenicity rate.

Clinical and Epidemiological Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Infections in a Tertiary Hospital in China.

Purpose: Infections caused by carbapenem-resistant Klebsiella pneumoniae (CR-KP) are an important public health problem. This study aimed to evaluate the clinical characteristics of patients with CR-KP. Methods: A retrospective cohort study was conducted of all patients with CR-KP infection. A total of 615 patients with CR-KP infection were identified and 135 patients who did not meet the eligibility criteria were excluded. Clinical characteristics, antimicrobial regimens, and patient outcomes were analyzed. Results: The overall mortality rate of CR-KP infections was 37.3% and the mortality rate in patients with bloodstream infections was 66.2%. Survival analysis revealed that there were statistically significant differences between patients with bloodstream infections and those with pulmonary and drainage fluid infections. Logistics regression analysis showed that hemopathy, age >60 years, solid tumors, diabetes, septic shock, acute kidney injury, and stroke were independent predictors of 30-day mortality rate. The chi-square test showed that treatment with a combination of carbapenems, tigecycline, and polymyxin B was superior to treatment with carbapenems with polymyxin B, without tigecycline. Conclusions: CR-KP infections, especially bloodstream infections, have a high mortality rate. The outcome is strongly dependent on patients' clinical conditions. Antimicrobial regimens combining carbapenems, tigecycline, and polymyxin B might be a better choice.

Effect of pulse duration on the above-threshold ionization of a hydrogen atom irradiated by a 400 nm intense laser.

The photoelectron emission spectra generated by the interaction between ultrashort intense laser pulses and atoms can reveal the ultrafast dynamics of electrons. By using the numerical solution of the time-dependent Schrödinger equation in momentum space, the photoelectron emission spectra of atoms irradiated by 400 nm intense lasers with different durations of the pulse has been investigated. In the photoelectron emission spectrum, in addition to the above-threshold ionization peaks due to ionization interference in multiple cycles and the sideband peaks mainly due to the interference of ionized electrons at different moments along the rising edge of the laser pulse envelope, additional peaks of photoelectron emission whose intensity appears to oscillate with the increasing duration of the laser pulse can also be observed. Based on strong-field approximation and the population's analysis of the bound state, it is found that these photoelectron peaks originate from the ionization of the excited state and the oscillations of these peaks are due to the superposition of their peak energy positions with the sideband energy positions. Furthermore, it is demonstrated that the energy positions of the maximum intensity of the photoelectron emission spectra move towards the higher energy end as the duration of the driving laser pulse extends. This phenomenon can be attributed to the fact that the main moment of ionization of atoms changes with the increasing duration of the driving laser pulse, thus allowing the real-time ionization of atoms to be probed using photoelectron emission spectra.

Acoustic source localization using L-shaped sensor clusters: A review.

Acoustic source localization (ASL) plays an important role in structural health monitoring (SHM). The L-shaped sensor cluster (LSSC) is very convenient for ASL, and hence SHM. Various techniques based on LSSC have been developed rapidly in the past decade. LSSC can be conveniently used for damage detection and localization, a necessary step for monitoring structures through non-destructive testing (NDT). After ten years of development, LSSC still has a wide development space. In this paper, the fundamental roles of LSSC in developing different techniques within last ten years and its future potentials are discussed. The LSSC-based time difference of arrival localization techniques and the wave front shape-based localization techniques are reviewed in detail in this paper. This paper aims to give readers a more comprehensive and clear understanding of these techniques. The discussion on the advantages and disadvantages of these techniques and various sources of the errors will give the readers the current limitations and future development prospects of ASL and damage detection techniques using LSSC.

Effect of axial stresses on longitudinal guided waves in a fluid-filled pipe.

This paper describes the study of the acoustic field of a fluid-filled pipe subjected to axial stress based on the acoustoelastic theory. The pipe with applied axial stresses can be approximated as a transversely isotropic pipe, and hence, its acoustic fields can be expressed using potential functions. The velocity changes of longitudinal wave modes with applied stresses are analyzed for the pipe filled with oil by an analytical method. It was found that the longitudinal mode velocity changes almost uniformly with the applied stresses. The high speed and low frequency plateaus of longitudinal wave modes are sensitive to stress. The relationship between stress and the velocity change of the guided wave is given. The results indicate that non-destructive testing techniques using longitudinal wave modes have strong potential to identify and monitor the stress levels in pipe structures.

Study on immune status alterations in patients with sepsis.

Sepsis, characterized by cytokine-mediated hyper-inflammation and a consistent decline in immune responsiveness, is associated with a high risk of death in the intensive care unit (ICU). Here, we for the first time investigated the changes in immune and inflammatory responses to understand the interactions between immune and inflammatory biomarkers and their association with patient outcomes. The cytokine and lymphocyte subset levels were analyzed in healthy donors (HD) and patients with sepsis upon admission to the ICU (D0), D3, D7, D14, and D28 using flow cytometry. The primary endpoint was mortality on day 90. The trends in lymphocyte subsets and cytokine levels in all patients (n = 47), HD (n = 27), and patient subgroups (surviving, n = 30; dead, n = 17) were analyzed using an independent sample t-test and principal component analysis. Age, steroids (steroids used > 48 h), secondary infection, acute heart failure, acute kidney injury, coagulopathy, hypohepatia, organ transplant and septic shock (when transferred to the ICU) were associated with mortality. Absolute lymphocyte counts and lymphocyte subsets levels were reduced in most patients with sepsis. The proportion of Tregs in the patients increased with disease progression and was associated with immunosuppression. In conclusion, sepsis downregulated adaptive immunity, and induced the transition of the patients to prolonged immune suppression. The study suggests that while cellular immunity recovered within 2 weeks of admission, humoral and innate immunity recovery takes longer. These findings may assist in developing appropriate therapeutic approaches to improve the immune responses in patients with sepsis.

Influence of multiphoton resonance excitation on the above-threshold ionization of a hydrogen atom.

The photo-electron emission of a hydrogen atom irradiated by an ultraviolet laser pulse is investigated by numerically solving the time-dependent Schrödinger equation in momentum space. A subpeak structure with high intensity is observed in the photo-electron emission spectrum, and the peak of the enhanced structure shifts to a higher energy as the laser intensity increases. Through the strong-field approximation and the analysis of the population of the bound state , it is found that this subpeak structure is generated from the interference between the ionized electrons from the ground state and the ionized electrons from the 2p state after the resonant transition from the ground state to the 2p state. Analyzing the change rule of the photo-electron emission spectrum can further deepen the understanding of the energy change of the dressed bound state for an atom irradiated by an intense laser pulse.

Factors influencing and long-term effects of manual myotomy phenomenon during physiotherapy for congenital muscular torticollis.

PURPOSE: To investigate the factors influencing and long-term effects of manual myotomy (MM) occurring during physiotherapy for congenital muscular torticollis (CMT). METHODS: We retrospectively collected the clinical data of children with CMT receiving physiotherapy between 2008 and 2018. The children were divided into manual myotomy (MM) and non-manual myotomy (NMM) groups according to whether MM occurred during treatment. We assessed physiotherapy outcomes in children with CMT using craniofacial asymmetry parameters and the Cheng-Tang rating score. By measuring the ear-eye distance, ear-nose distance, eye-mouth distance, ear-mouth distance, half-head circumference, and half-head top at two sides to evaluate craniofacial asymmetry. Based on the Cheng-Tang assessment criteria, we recorded the range of rotation, range of lateral flexion, the status of the contracted muscle, the hardness of the mass, the extent of head tilting during activities and sleeping, the status of daily activities, face size, type of head shape, cranial changes, and subjective head tilting to assess the effectiveness of treatment. Clinical data and outcome indicators (craniofacial asymmetry parameters and Cheng-Tang rating score) were compared. RESULTS: The MM group had a significantly higher total Cheng-Tang rating score than the NMM group (P < 0.05). Age at initial physiotherapy session was the risk factor for MM during physiotherapy. CONCLUSION: Children with CMT developing MM during physiotherapy generally have a good outcome, although we do not recommend MM as a goal of treatment. Physiotherapists should understand this phenomenon, assess relevant factors to predict risk, and carefully observe treatment to prevent possible complications.

Modelling and simulation of borehole seismoelectric response with an impermeable wall.

In this paper, we construct a borehole model with an impermeable/permeable wall and study the seismoelectric responses. First, we define the boundary conditions at the borehole wall, then the acoustic field and electric field are simulated by the real axis integral method. In order to have a comprehensive analysis of the body wave components, we use the secant integral method to simulate the body waves and give the excitation intensity spectrum in the frequency domain. The results show that the impermeability of the borehole wall significantly increases the amplitude of the acoustic field generated by Stoneley waves. This is because the closed pores at the boundary make Stoneley waves energy leak more slowly and hence attenuating less. The impermeable borehole wall weakens the electromagnetic interface response. Besides, both P wave and S wave and their accompanying electric field properties are affected by boundary connectivity. This investigation provides a theoretical basis for qualitatively judging borehole wall permeability by the seismoelectric signals.

Upper limb pediatric fractures in 22 tertiary children's hospitals, China: a multicenter epidemiological investigation and economic factor analysis of 32,832 hospitalized children.

BACKGROUND: Fractures are the most common type of unintentional injury in children, with traumatic upper limb fractures accounting for approximately 80% of all childhood fractures. Many epidemiological investigations of upper limb fractures in children have been conducted, but with the development of society, the patterns of childhood fractures may have changed. This study aimed to analyze the epidemiology and economic cost factors of upper limb fractures in Chinese children. METHODS: We retrospectively reviewed children with upper limb fractures or old upper limb fractures hospitalized between December 1, 2015, and December 31, 2019, in 22 tertiary children's hospitals, under China's Futang Research Center of Pediatric Development. We used the ICD10 codes on the front sheet of their medical records to identify cases and extracted data on age, sex, injury cause, fracture site, treatment, the year of admission and discharge, visiting time, and various costs during hospitalization from the medical record. RESULTS: A total of 32,439 children (21,478 boys and 10,961 girls) were identified, of whom 32,080 had fresh fractures and 359 had old fractures. The peak age was 3-6 years in both sexes. A total of 4788 were infants, 14,320 were preschoolers, 10,499 were in of primary school age, and 2832 were adolescent. Fractures were most frequent in autumn (August to October). Admissions peaked at 0 o'clock. Among the 32,080 children with fresh upper limb fractures, the most common fracture site was the distal humerus, with a total of 20,090 fracture events including 13,134 humeral supracondylar fractures and 4914 lateral humeral condyle fractures. The most common cause of injuries was falling over. The most common joint dislocation accompanying upper limb fractures occurred in the elbow, involving 254 cases. Surgery was performed in 31,274 children, and 806 did not receive surgery. Among those with clear operative records, 10,962 children were treated with open reduction and 18,066 with closed reduction. The number of cases was largest in the East China region (Anhui Province, Shandong Province, Jiangsu Province, Zhejiang Province, and Fujian Province), with 12,065 cases overall. Among the 359 children with old fractures, 118 were admitted with a diagnosis of "old humerus fracture," accounting for the highest proportion; 244 underwent surgical open reduction, 16.16% of whom had osteotomy. For the children with fresh fractures, the average total hospital cost was 10,994 yuan, and the highest average total hospital cost was 14,053 yuan, for humeral shaft fractures. For the children with old fractures, the average total hospital cost was 15,151 yuan, and the highest average total hospital cost was 20,698 yuan, for old ulna fractures. Cost of materials was the principle factor affecting total hospital cost, followed by surgery and anesthesia costs, both in children with fresh fractures and those with old fractures. Significant differences were observed in all hospital costs (P < 0.001) except treatment costs (P = 0.702), between children with fresh fractures and those with old fractures. Among the 32,439 children, full self-payment accounted for the highest proportion of all payment methods, involving 17,088 cases, with an average cost of 11,111 yuan. CONCLUSION: Information on the epidemiological characteristics of childhood fractures suggests that health and safety education and protective measures should be strengthened to prevent upper limb fractures in children. For both fresh and old fractures, the cost of materials was the principal factor affecting total hospital cost, followed by surgery and anesthesia costs. The overall average total hospital cost is higher in children with old fractures than in children with fresh fractures. Among all children, full self-payment, at 53% of children, accounted for the highest proportion of all payment methods. Hospital costs are a headache for those families who will pay on their own. It can lead to a delayed treatment and unhealed fractures or malunion in some children. Therefore, the child trauma care system and training on fractures need to be improved, to reduce the late presentation of fractures. These combined measures will improve children's quality of life, reduce the expenditure of families, and decrease the public health burden. To provide better medical services for children, authorities must improve the allocation of health resources, establish a comprehensive medical security system for children, and set up more child trauma centers.

High-throughput production of kilogram-scale nanofibers by Kármán vortex solution blow spinning.

The interaction between gas flow and liquid flow, governed by fluid dynamic principles, is of substantial importance in both fundamental science and practical applications. For instance, a precisely designed gas shearing on liquid solution may lead to efficacious production of advanced nanomaterials. Here, we devised a needleless Kármán vortex solution blow spinning system that uses a roll-to-roll nylon thread to deliver spinning solution, coupled with vertically blowing airflow to draw high-quality nanofibers with large throughput. A wide variety of nanofibers including polymers, carbon, ceramics, and composites with tunable diameters were fabricated at ultrahigh rates. The system can be further upgraded from single thread to multiple parallel threads and to the meshes, boosting the production of nanofibers to kilogram scale without compromising their quality.

Epidemiology and management of 10,486 pediatric fractures in Shenzhen: experience and lessons to be learnt.

PURPOSE: To explore and analyze the causes and related influencing factors of pediatric fractures, and provide theoretical basis for reducing the incidence and adverse effects of pediatric fractures. METHODS: This study retrospectively analyzed the epidemiological characteristics of fractures in pediatric aged ≤18 years old who were admitted to the our hospital between July 2015 and February 2020. RESULTS: A total of 10,486 pediatric patients were included in the study, of whom 6961 (66.38%) were boys, and 3525 (33.62%) were girls. For the fracture incidence, age group of the 3-6 years reached the peak. 5584 (60.76%) children were operated upon within 12 h after admission. The top three types of fractures were the distal humerus (3843 sites, 27.49%), distal ulna (1740 sites, 12.44%), and distal radius (1587 sites, 11.35%). The top three causes of injury were falls (7106 cases, 82.10%), car accidents (650 cases, 65.72%), and clipping (465 cases, 5.37%). Fractures predominantly occurred between July and November (4664 cases, 48.87%) and on Saturdays and Sundays (3172 cases, 33.24%). The highest number of hospital visits occurred between 20:00 and 00:00 (4339 cases, 45.46%). CONCLUSION: For pediatric fractures, we should take appropriate and effective preventive measures to reduce the incidence of children's fractures according to the distribution characteristics of age, gender, cause of injury, and fracture site.

Epidemiology of skeletal trauma and skull fractures in children younger than 1 year in Shenzhen: a retrospective study of 664 patients.

BACKGROUND: Unintentional injury is one of the top three causes of death for infants. However, the epidemiological studies of skeletal trauma and skull fractures in infants younger than 1 year were poorly understood in China. Therefore, our study aimed to examine accidental and emergency attendance in infants under 1 year. It also tried to determine the prevalence and severity of accident types in infants. METHODS: A retrospective analysis was performed on the demographic characteristics of infants younger than 1 year with skeletal trauma and skull fractures who visited the Shenzhen Children's Hospital from January 1, 2016 to December 31, 2019. Age, gender, fracture site and type, mechanism of injury, length of visit, length of hospital stay, hospitalization cost, and treatment methods were analyzed. RESULTS: A total number of 675 fractures in 664 infants were included, the median age was 187days (IQR,90-273days), including 394 males and 270 females. The top three fracture sites were the skull (430 sites, 63.70 %), long bones of the limbs (168 sites, 24.89 %), and clavicle (53 sites, 7.85 %). The top three causes of injury were locomotion injuries (256 cases, 38.55 %), falls or trips from low height (from beds, tables, chairs, etc.) (130 cases, 19.58 %), and birth injuries (97 cases, 14.61 %). The greatest amount of fractures occurred in children 1-28 days of life (d) reached a top of 101 cases, followed by 331-365 days, accounting for 15.21 and 10.24 %, respectively. The number of fractures reached a trough of 29 cases in the 29-60d group (4.37 %). And increased again to 65 cases in the 151-180d group (9.79 %). The proportion remained relatively constant at 9 % in the 181-210d group (9.19 %) and 211-240d group (9.64 %). The interval between injury and visiting our hospital was ≤ 72 h in 554 cases. CONCLUSIONS: Special attention should be given to the demographic characteristics of fractures in infants under 1 year of age, and appropriate outreach should be implemented. For example, health education should be provided to aid in the prevention especially for frequently occurring locomotion injuries, and prompt access to specialist medical care should be recommended for skull fractures, which are prone to delayed treatment. In addition, multidisciplinary collaboration should be implemented in trauma care, while also promoting the establishment of trauma centers in specialist children's hospitals with a stronger capacity to treat pediatric trauma, and a regional system for pediatric trauma treatment.

Experimental Research on Rapid Localization of Acoustic Source in a Cylindrical Shell Structure without Knowledge of the Velocity Profile.

Acoustic source localization in a large pressure vessel or a storage tank-type cylindrical structure is important in preventing structural failure. However, this can be challenging, especially for cylindrical pressure vessels and tanks that are made of anisotropic materials. The large area of the cylindrical structure often requires a substantial number of sensors to locate the acoustic source. This paper first applies conventional acoustic source localization techniques developed for the isotropic, flat plate-type structures to cylindrical structures. The experimental results show that the conventional acoustic source localization technique is not very accurate for source localization on cylindrical container surfaces. Then, the L-shaped sensor cluster technique is applied to the cylindrical surface of the pressure vessel, and the experimental results prove the applicability of using this technique. Finally, the arbitrary triangle-shaped sensor clusters are attached to the surface of the cylindrical structure to locate the acoustic source. The experimental results show that the two acoustic source localization techniques using sensor clusters can be used to monitor the location of acoustic sources on the surface of anisotropic cylindrical vessels, using a small number of sensors. The arbitrarily triangle-shaped sensors can be arbitrarily placed in a cluster on the surface of the cylindrical vessel. The results presented in this paper provide a theoretical and experimental basis for the surface acoustic source localization method for a cylindrical pressure vessel and lay a theoretical foundation for its application.

The Effectiveness and Safety of Botulinum Toxin Injections for the Treatment of Congenital Muscular Torticollis.

OBJECTIVE: Botulinum toxin have been used to treat congenital muscular torticollis for the last 25 years; however, few studies have been published with only limited cases and short-term follow-up. The aim of the present study is to systematically review the effectiveness and safety of botulinum toxin injections for congenital muscular torticollis by analyzing these relevant literatures. METHODS: The authors searched PubMed, Web of Science, EMBASE, Cochrane Library, China Biology Medicine, for all articles about botulinum toxin injections for the congenital muscular torticollis. The MINORS evaluation tool was adopted to evaluate the quality of these studies. Meta-analysis calculations are made by R software 3.6.2. RESULTS: This study search involved strict inclusion criteria and targeted data collection. Ten studies were included, with a total of 411 patients, comprising 1 non-randomized experimental study and 9 cases or case series. The results of our meta-analysis of single rate showed that the overall effective rate of botulinum toxin for congenital muscular torticollis was 84% (95% confidence interval [CI] 67%-96%). After botulinum toxin treatment, the conversion rate to surgery was 9% (95% CI 4%-22%), and the adverse reaction rate was 1% (95% CI 0%-3%). The most common adverse reactions among these included studies involve injection site erythema and transient dysphagia. CONCLUSION: Current evidence shows that botulinum toxin injections for the treatment of congenital muscular torticollis is safe and effective, with few serious adverse reactions. Further well-designed, larger randomized trials are warranted.

[Adsorption Characteristics and Mechanism of Cadmium in Water by Alkali and Magnetic Composite Modified Wheat Straw Biochar].

Wheat straw biochar (BC) was modified by KOH and magnetics to generate composited modified biochar (FKC). Based on characterization by scanning electron microscopy-energy dispersive spectrometry (SEM-EDS), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and magnetic (VSM) techniques, the adsorption characteristics and mechanisms of Cd2+ in water and the effects of temperature, pH value, and dosage on the adsorption characteristics of FKC were studied. The results showed that the modified biochar was loose and porous. The specific surface area of FKC increased by 19.11 times, the number of aromatic and oxygen-containing functional groups such as O-H, C=O, and C=C increased, and a new functional group Fe-O formed compared to the BC. FKC is magnetic, and its magnetization is 8.43 emu·g-1, which can be recycled and reused. The adsorption of Cd2+ by FKC fitted well with the pseudo-second-order kinetic model and the Langmuir model, indicating that chemical adsorption is the main adsorption mechanism. The theoretical maximum equilibrium adsorption capacity of FKC is 23.44 mg·g-1, which is 1.47 times that of BC. The thermodynamic parameters suggested the adsorption of Cd2+ by FKC was a spontaneous and endothermic process. The adsorption capacity increased with an increase of pH in the region 2-8, and a biochar dosage of 10 g·L-1 was used. After three cycles of adsorption-desorption-adsorption, the adsorption capacity of Cd2+ by FKC still reached 17.71 mg·g-1, indicating that FKC has good reusability. These results can provide a theoretical basis for the application of KOH and magnet-modified biochar from wheat straw to remove heavy metals from contaminated wastewater.

Impact of copper oxide nanoparticles on the germination, seedling growth, and physiological responses in Brassica pekinensis L.

Wide application of nanoparticles causes considerable environmental, health, and safety problems. However, their potential impact and mechanisms on plant growth are not completely clear. In the present study, the effects of different concentration of copper oxide nanoparticles (nCuO) on seed germination and seedling growth, as well as physiological parameters of Brassica pekinensis L., were investigated. The seeds were exposed to 10-, 100-, and 1000-mg L-1 nCuO suspensions and 0.8-mg L-1 Cu2+ released from 1000-mg L-1 nCuO for 7 day. The results showed that nCuO did not affect the germination rate, germination potential, and germination index of B. pekinensis but significantly affected the vitality index. The growth of roots and shoots of B. pekinensis was promoted at 10-mg L-1 nCuO, while they were inhibited under 1000-mg L-1 nCuO and Cu2+ ion treatments, and roots suffered more damage than shoots. Cu content in shoots and roots of B. pekinensis increased with increasing concentrations of nCuO, which is significantly higher in roots as compared with shoots. Roots and shoots accumulated more Cu under nCuO treatments compared with Cu2+ ion treatment. nCuO treatments led to significant lignification in roots of B. pekinensis. Furthermore, nCuO increased in the contents of soluble sugar and protein in shoots, while nCuO at 1000 mg L-1 significantly inhibited the content of soluble protein in roots. In addition, concentration-dependent augmentation of lipid peroxidation, hydrogen peroxide and superoxide generation, and antioxidant enzyme activity were noticed in shoots and roots of B. pekinensis seedlings under nCuO and Cu2+ ion treatments. Altogether, the results strongly suggested that the phytotoxicity of nCuO in B. pekinensis was caused by both the nanoparticles itself and the released Cu2+ ions.

Effects of nonlinear parameter of fluid-solid coupling on acoustic field in porous media.

The purpose of this Letter to the Editor is to demonstrate the effects of the nonlinear parameter of fluid-solid coupling on the acoustic field in porous media. The nonlinear acoustic field excited by a one-dimensional finite-amplitude shear wave propagating in the uniform and infinite saturated porous media is studied. Researchers use the complete strain energy formula with third-order terms of strain in saturated porous media. The formula for calculating the fluid-solid coupling nonlinear parameter γ from the dynamic compatibility condition is given. To illustrate the effect of the fluid-solid coupling nonlinear term on the nonlinear acoustic field excited by the longitudinal and transverse waves, this study compares nonlinear acoustic fields excited by a finite amplitude wave with and without nonlinear parameter γ. The results show that the nonlinear parameter γ has an influence on the nonlinear acoustic field excited by the one-dimensional shear wave, but it has no influence on the nonlinear acoustic field excited by the one-dimensional longitudinal wave.

Enhanced stability and nitrogen removal efficiency of Klebsiella sp. entrapped in chitosan beads applied in the domestic sewage system.

Although numerous denitrifying bacteria have been isolated and characterized, their capacity is seriously compromised by traditional inoculant addition and environmental stress in open bioreactors for wastewater treatment. In this study, a biocompatible material, chitosan, was used as a carrier to immobilize a simultaneously heterotrophic nitrifying-aerobic denitrifying bacterium Klebsiella sp., KSND, for continuous nitrogen removal from domestic wastewater in an open purification tank. The results showed that immobilization had no significant effect on cell viability and was beneficial for the reproduction and adhesion of cells. The entrapped KSND exhibited a slightly higher nitrogen removal efficiency of 90.09% than that of free KSND (87.69%). Subsequently, repeated batch cultivation experiments and analysis of the effects of organic contaminants and metal ions were performed using artificial wastewater and domestic wastewater. The findings revealed that the immobilized KSND beads presented desirable biophysical properties with good mechanical stability, cell viability, and enrichment, remarkable stability in organic contaminants and metal ions, and high efficiency nitrogen removal capacity. In conclusion, the developed immobilized denitrifying bacteria system has great potential for continuous wastewater treatment in open bioreactors.