Fluidization-melting characteristics of fly ash from municipal solid waste incineration

Fly ash (FA) from municipal solid waste incineration contains hazardous substances such as dioxins, furans, and heavy metals. Melting FA has proved to be an effective method for reducing volume and mass, while also rendering the waste harmless. However, during the melting process, the addition of a fluxing agent with calorific value is currently necessary to increase melting capacity and reduce energy consumption, which presents a challenge. To tackle this issue, a fluidization-melting technology for a fuel/FA mixture is proposed, wherein a fuel source is employed in the melting process, producing ash that can serve as a fluxing agent. To test this approach, rice husk (RH) was utilized as fuel in a small-scale fluidization-melting test. The objective of this study was to examine the operation parameters of the platform and the characteristics of the resulting product, and to evaluate the harm reduction effect of the slag and its potential for resource utilization. The operating temperature was set at 690 °C in the thermal modification unit and at 1450 °C in the melting furnace, resulting in stable operation and continuous liquid slag discharge. The leaching toxicity of heavy metals in the obtained slag was lower than the standard limit, achieving harmless disposal of FA. However, the resource utilization potential of the obtained slag is limited due to its failure to meet the criteria of vitrified substance and environmental quality requirements. These limitations could be addressed by promoting the combustion of carbon in the melting furnace and accelerating the cooling rate of the slag in the quenching unit.

Fixed-Field IMRT for Cervix Carcinoma Patients on an MR-LINAC Platform: Dosimetric Feasibility and Challenges

PURPOSE/OBJECTIVE(S)

To investigate the impact of MR-LINAC performance characteristics and inverse planning implementation on the feasibility of fixed-field IMRT for cervix carcinoma patients by benchmarking MR-LINAC plans against clinically used VMAT plans in a single institution study and multi-institutional treatment planning challenge.

MATERIALS/METHODS

For 10 cervix cancer patients who had previously received Linac-based VMAT, new treatment plans were optimized for MR-LINAC IMRT using 6X FFF fixed fields with maximum available field size of 27.4 x 24.1 cm2. Dose optimization was performed on the clinically used planning CT and structure set. Prescribed dose was 48.6 Gy in 27 fractions for all patients with 6 patients receiving an additional integrated boost for a total of 58.05 Gy to involved nodes. Constraints were based on our institutional protocol as per Table 1. IMRT delivery time was limited to 20 min. Original clinically used VMAT plans were generated on Eclipse (Varian Medical System) using 3 to 4 arcs. For the multi-institutional planning challenge, the data set from a single patient was anonymized and shared to participants. Participants used a single MR-based Linac planning platform to generate a plan based on our institutional constraints, with maximum treatment time limited to 20 min. For all analyses, a paired samples t-test was used to compare the significance defined at p < 0.05.

RESULTS

For MR-LINAC plans, the mean number of fields used was 23, mean number of segments 229, and the average estimated treatment delivery time was 17.3 minutes. MR-LINAC plans showed a significantly higher heterogeneity and dose to organs at risk compared to VMAT plans (Table 1). For the planning challenge, a total of 30 participants registered interest. Of this, seven plans were submitted to the challenge. On average, participants generated a plan that would be acceptable based on our institutional constraints (Table 1). However, the volumetric dose to bowel and pelvic bones were higher on MR-LINAC plans compared to the reference VMAT plan.

CONCLUSION

MR-LINAC fixed-field IMRT for cervix cancer patients is feasible but system constraints and optimization implementation result in greater dose heterogeneity and worse organ-at-risk sparing compared to Linac based VMAT. Further research is needed to determine if potential reduction of treatment margins, allowed by better MRI soft-tissue visualization, will result in MR-LINAC IMRT superior to Linac VMAT.

[Analysis on missed diagnosis or misdiagnosis of anomalous origin of left coronary artery from pulmonary artery by echocardiography from one single medical center]

Objectives: To analyze the reasons of missed diagnosis or misdiagnosis on anomalous origin of left coronary artery from pulmonary artery (ALCAPA) by echocardiography. Methods: This is a retrospective study. Patients with ALCAPA who underwent surgical treatment in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from August 2008 to December 2021 were included. According to the results of preoperative echocardiography and surgical diagnosis, the patients were divided into confirmed group or missed diagnosis/misdiagnosis group. The results of preoperative echocardiography were collected, and the specific echocardiographic signs were analyzed. According to the experience of the doctors, the echocardiographic signs were divided into four types, namely clear displayed, vague/doubtful displayed, no display and no notice, and the display rate of each sign was calculated (display rate=number of clearly displayed cases/total number of cases×100%). By referring the surgical data, we analyzed and recorded the pathological anatomy and pathophysiological characteristics of the patients, and the rate of missed diagnosis/misdiagnosis of echocardiography in patients with different characteristics was compared. Results: A total of 21 patients were enrolled, including 11 males, aged 1.8 (0.8, 12.3) years (range 1 month to 47 years). Except for one patient with anomalous origin of left anterior descending artery, the others were all originated from the main left coronary artery (LCA). There were 13 cases of ALCAPA in infant and children, and 8 cases of adult ALCAPA. There were 15 cases in the confirmed group (diagnostic accuracy was 71.4% (15/21)), and 6 cases in the missed diagnosis/misdiagnosis group (three cases were misdiagnosed as primary endocardial fibroelastosis, two cases were misdiagnosed as coronary-pulmonary artery fistula; and one case was missed diagnosis). The working years of the physicians in the confirmed group were longer than those in the missed diagnosis/misdiagnosed group ((12.8±5.6) years vs. (8.3±4.7) years, P=0.045). In infants with ALCAPA, the detection rate of LCA-pulmonary shunt (8/10 vs. 0, P=0.035) and coronary collateral circulation (7/10 vs. 0, P=0.042) in confirmed group was higher than that in missed diagnosis/misdiagnosed group. In adult ALCAPA patients, the detection rate of LCA-pulmonary artery shunt was higher in confirmed group than that in missed diagnosis/misdiagnosed group (4/5 vs. 0, P=0.021). The missed diagnosis/misdiagnosis rate of adult type was higher than that of infant type (3/8 vs. 3/13, P=0.410). The rate of missed diagnosis/misdiagnosis was higher in patients with abnormal origin of branches than that of abnormal origin of main trunk (1/1 vs. 5/21, P=0.028). The rate of missed diagnosis/misdiagnosis in patients with LCA running between the main and pulmonary arteries was higher than that distant from the main pulmonary artery septum (4/7 vs. 2/14, P=0.064). The rate of missed diagnosis/misdiagnosis in patients with severe pulmonary hypertension was higher than that in patients without severe pulmonary hypertension (2/3 vs. 4/18, P=0.184). The reasons with an echocardiography missed diagnosis/misdiagnosis rate of≥50% included that (1) the proximal segment of LCA ran between the main and pulmonary arteries; (2) abnormal opening of LCA at the right posterior part of the pulmonary artery; (3) abnormal origin of LCA branches; (4) complicated with severe pulmonary hypertension. Conclusions: Echocardiography physicians' knowledge of ALCAPA and diagnostic vigilance are critical to the accuracy of diagnosis. Attention should be paid to the pediatric cases with no obvious precipitating factors of left ventricular enlargement, regardless of whether the left ventricular function is normal or not, the origin of coronary artery should be routinely explored.

Experimental study and theoretical analysis on fluidized activation of coal gasification fly ash from an industrial CFB gasifier

The gasification fly ash (GFA), a bulk industrial solid waste from coal gasification process, urgently needs to be effectively disposed. In order to use the GFA as porous carbon materials, fluidized activation experiments of the GFA from an industrial circulating fluidized bed (CFB) gasifier were conducted in a bench-scale CFB test rig, as well as steam activation experiments of GFA in a vertical tube furnace and theoretical analysis on the activation process. Due to the ultrafine particle size, the GFA faces a fluidization problem and auxiliary particles are needed to stabilize its fluidization. In the fluidized activation, the pore structure of GFA particles becomes developed in a seconds-level time (about 1.5 s). The specific surface area (S_BET) of activated GFA increases with temperature, maximally increasing by 48.9 % and reaching 204 m²/g. Steam activation experiments show that the GFA has an activation potential of 362 m²/g (S_BET) and the pore structure evolution of GFA can be quantified by carbon conversion ratio. Based on this, the fluidized activation of GFA is found in the stage of pore development. By appropriately increasing the carbon conversion ratio (below 40 %), the fluidized activation effect of GFA is expected to be improved. Theoretical analysis indicates for the GFA the features of ultra-fine particle size and well-developed pore structure greatly enhance the diffusion rate of active component into the particles. Under the strong diffusion effect, increasing temperature is a critical means to realize the rapid and effective activation of GFA in a finite time.

[Effect analysis of treating intracranial wide-neck bifurcation aneurysms through Woven EndoBridge]

Objective: To explore the clinical effect of Woven EndoBridge (WEB) in the treatment of wide-neck bifurcation aneurysms. Methods: The clinical and imaging data of 11 patients with intracranial wide-neck bifurcation aneurysms treated by WEB alone at Department of Neurosurgery of the Northern Theater General Hospital from September 2017 to May 2018, were retrospectively analyzed. The patients were 7 males and 4 females, aged (54±11) years (ranged from 31 to 66 years). The aneurysms of 5 patients were located in the anterior communicating artery, 3 in the top of the basilar artery, and 3 in the bifurcation of the middle cerebral artery. The intraoperative and postoperative conditions of the patients were recorded, and the degree of aneurysm embolization was evaluated by WEB embolization aneurysm occlusion scale (WOS). Results: The intraoperative WEB release of all the 11 patients was good, with 3 cases of WOS grade A, 1 of grade B and 7 of grade C, with no intraoperative acute complications occurring. The imaging follow-up was not carried out in 1 patient due to economic reason, and the clinical follow-up was good until 3 years after the operation; 10 patients were followed up by imaging for 6 months to 3 years, and no postoperative complications occurred in the target treatment area. Among the 2 patients with WOS grade A and 1 patient with grade B during operation, according to the postoperative follow-up, all were WOS grade A; among the 7 patients with WOS grade C during operation, 4 were still of grade C and 3 were of grade D according to the follow-up. Among the 3 patients with WOS grade D, 1 patient received secondary embolization due to poor recurrence morphology, unstable hemodynamics and high possibility of rupture of aneurysm, stent assisted coil embolization was adopted, with good immediate effect; the other 2 cases had recurrent aneurysms, but the aneurysms had good morphology and stable hemodynamics, therefore, clinical follow-up was continued and no secondary surgery was performed. No complications occurred in all these 11 patients. Conclusions: The operation of treating unruptured intracranial wide-neck bifurcation aneurysms with WEB device alone is simple, and there is no need for anticoagulation and antiplatelet treatment before and after the operation, the clinical effect is being good. WEB device provides a new treatment option for intracranial wide-neck bifurcation aneurysms.

Application of post-combustion ultra-low NOx emissions technology on coal slime solid waste circulating fluidized bed boilers

In order to achieve thermal treatment of coal slime and depth control of NO_x, a 75 t/h circulating fluidized bed (CFB) boiler arranging post-combustion air is constructed. In the experiment, the combustion atmosphere and the ratio of primary air and secondary air are adjusted to decrease the NO_x emissions below 50 mg/m³ (dry basis at 6% O₂). Compared with conventional CFB combustion, the post-combustion technology decreases the NO_x emissions from 92.9 to 65.4 mg/m³ by adjusting the combustion atmosphere. Then, the primary air volume is adjusted to decrease the NO_x emissions further. On the one hand, decreasing primary air volume contributes to inhibiting the NO_x generation in the dense phase. On the other hand, it is proved that the combination of the cyclone and a post-combustion chamber plays a crucial role in the de-NO_x process of post-combustion technology. More char particles are brought to the cyclone as the primary air volume decreases. The NO_x reduction in the cyclone and the post-combustion chamber is promoted. Finally, the NO_x emissions are decreased to 42.6 mg/m³ when the ratio of primary air and secondary air is 50.0%. In addition, the SO₂ emissions and the combustion efficiency during the ultra-low NO_x condition are 23.2 mg/m³ and 98.3%, respectively.

[Comparison of single incision robot-assisted laparoscopic radical prostatectomy with and without extraperitoneal special channel device]

Objective: To compare the clinical effects of single-incision robot-assisted laparoscopic radical prostatectomy (RARP) with and without extraperitoneal special channel device. Methods: The clinical data of 70 patients who had undergone RARP in the Robotic Minimally Invasive Surgery Center of Sichuan Provincial People's Hospital from September 2020 to February 2021 were analyzed retrospectively, including 29 cases who were operated on without special channel device (group A) and 41 cases with special channel device (group B). All operations were performed by robot-assisted single-incision retrograde bladder neck exfoliation via extraperitoneal approach in patients by the same operator. The operation time, intraoperative blood loss, the bladder neck urethral anastomosis time, postoperative hospital stay, postoperative exhaust time, positive rate of incisal margin, indwelling time of urinary catheter, retention rate of postoperative erectile function, satisfaction rate of immediate postoperative urine control, positive rate of postoperative lymph node pathology, incision length, treatment cost and the rate of prostate specific antigen (PSA)lower than 0.2 μg/L at 6 weeks after operation were compared between the two groups. Results: All 70 cases were operated successfully. The difference of age[ (68.9±3.9) vs (69.4±5.4) years], preoperative PSA level[14.1(6.3, 19.8)vs13.7(5.8, 18.1)μg/L], prostate volume[44.8(30.7,172.6)vs 56.3(40.9,163.4)ml ] of the two groups was not statistically significant(all P>0.05). The difference of operation time [ (59.1±18.5) vs (59.6±18.0) min ], intraoperative blood loss [93(66,198)vs 95(68,203) ml ], bladder neck urethral anastomosis time [ (12.6±1.3) vs (13.7±2.8) min ], postoperative hospital stay [ (8.1±2.3) vs (9.1±1.3) d], postoperative exhaust time [ (1.4±0.6) vs (1.3±0.6) d], positive rate of incisal margin (20.7% vs 19.5%), indwelling time of the urinary catheter after operation [ (6.8±1.5) vs (7.1±2.0) d ], the retention rate of postoperative erectile function (31.0% vs 27.0%), the satisfaction rate of immediate postoperative urine control (79.3% vs 75.6%), the positive rate of postoperative lymph node pathology (17.2% vs 14.6%), the length of incision [ (5.1±0.5) vs (6.1±0.4) cm ], the rate of PSA lower than 0.2 μg/L at 6 weeks after operation (86.2% vs 83.0%) of the two groups was not statistically significant(all P>0.05). The operation cost of group A[(62 000±4 000) yuan]was lower than group B[(68 000±4 000) yuan] (P<0.05). Conclusion: Extraperitoneal non-special channel device single-incision RARP is safe and feasible.

[Streptococcal toxic shock syndrome caused by Streptococcus pyogenes: a retrospective study of 15 pediatric cases]

Objective: To improve the understanding of clinical characteristics of streptococcal toxic shock syndrome (STSS) caused by Streptococcus pyogenes (S. pyogenes) in children. Methods: A retrospective study was conducted to analyze the clinical data of STSS caused by S. pyogenes (culture-confirmed) in 7 tertiary hospitals during 2010-2017 in China. Clinical and laboratory data were collected by reviewing the medical records. Results: Fifteen cases of STSS, including 9 males, were confirmed and the ages of the patients ranged from 6 months to 15 years, with median age of 3 years. All cases had the positive blood culture for S. pyogenes and only 3 cases had short course of β-lactam treatment before blood culture. Medical evaluation was initiated within (5.1±4.6) days after symptom onset. All patients had fever, and 13 patients had multiple organ dysfunction and 10 patients had disseminated intravascular coagulationl (DIC). Twelve cases had severe pneumonia with or without skin and (or) soft tissue infections. Underlying conditions included giant hemangioma of the skin in 2 patients and varicella in 1 patient. All isolated strains in 14 cases were sensitive to penicillin G, ceftriaxone/cefotaxime, vancomycin, but 12 and 13 isolates were resistant to clindamycin and erythromycin, respectively. Eight patients died, and 5 of them died within 24 hours after admission. One patient was lost to follow-up after intended discharge against medical advice. Conclusion: STSS caused by S. pyogenes in children is a severe syndrome with rapid clinical progression and high mortality rate, and thus the pediatricians should be aware of STSS and immediately initiate aggressive treatment for the suspected cases.

[Association of CYP19A1 gene rs7176005 single nucleotide polymorphism with breast cancer risk and clinicopathologic features of tumor]

Objective: The aim of this study was to investigate the association of the CYP19A1 rs7176005 single nucleotide polymorphism (SNP) with breast cancer risk and with clinicopathologic features of tumors. Methods: This study was conducted by including 138 patients with breast cancer (cancer group), those who diagnosed as primary breast cancer after operation by pathology. There were 293 cases in the group of benign breast disease which was presented as a solid mass by the color ultrasound and pathologically diagnosed as "fibroadenoma or adenosis" (benign breast disease group), the cases were paired with breast cancer patients by age±5 in the same period, and there were 259 cases in the group of healthy control who received routine physical examination during the same period and were paired with breast cancer patients by age±5 without any detection of breast related diseases (healthy control group) at West China hospital between September 2012 and November 2016. The CYP19A1 rs7176005 SNP was detected by a direct sequencing method. Hardy-Weinberg test was used to analyze the genetic balance of the 3 groups. Chi square test was used to compare the distribution of rs7176005 genotypes between the 3 groups, and the differences of clinicopathological features in breast cancer patients carrying different genotypes. Results: The ages of the breast cancer cases, the benign breast disease group and the healthy control group were (44.69±8.09), (42.33±11.44) and (41.92±9.61) years old, respectively. Hardy-Weinberg equilibrium test identified that the composition ratios of alleles C and T in breast cancer group, benign breast disease group and healthy group were not statistically significant (χ(2) values were 0.83, 0.34 and 0.04, respectively, P values were 0.363, 0.561, and 0.852, respectively). All the three groups met the genetic balance, had consistency and could represent the population. Among the 138 cases of breast cancer, the CYP19A1 rs7176005 SNP was significantly associated with the diameter of the tumor (P=0.031). The majority of tumor size was <2 cm in patients who carrying TT and CT genotypes, and the proportion was 75% (12/16) and 58% (40/69), respectively. While those patients with TT genotype were mainly >2 cm and ≤5 cm, and the proportion was 51% (27/53). The distribution of TNM stage among patients with different genotypes was also statistically significant (χ(2)=11.19, P=0.025). The most common stage was Ⅱ in Patients who carrying CC and CT genotypes, and the proportion was 45.3% (24/53) and 52.2% (36/69), respectively. While those patients with TT genotype was mainly in stage Ⅰ and the proportion was 56.3% (9/16). Conclusion: Though the CYP19A1 rs7176005 SNP is not associated with breast cancer development, breast cancer patients with the C allele exhibit a high tumor growth rate and large diameters.

Assessment of dynamic material properties of intact rocks using seismic wave attenuation: an experimental study

The mechanical properties of any substance are essential facts to understand its behaviour and make the maximum use of the particular substance. Rocks are indeed an important substance, as they are of significant use in the energy industry, specifically for fossil fuels and geothermal energy. Attenuation of seismic waves is a non-destructive technique to investigate mechanical properties of reservoir rocks under different conditions. The attenuation characteristics of five different rock types, siltstone, shale, Australian sandstone, Indian sandstone and granite, were investigated in the laboratory using ultrasonic and acoustic emission instruments in a frequency range of 0.1-1 MHz. The pulse transmission technique and spectral ratios were used to calculate the attenuation coefficient (α) and quality factor (Q) values for the five selected rock types for both primary (P) and secondary (S) waves, relative to the reference steel sample. For all the rock types, the attenuation coefficient was linearly proportional to the frequency of both the P and S waves. Interestingly, the attenuation coefficient of granite is more than 22% higher than that of siltstone, sandstone and shale for both P and S waves. The P and S wave velocities were calculated based on their recorded travel time, and these velocities were then used to calculate the dynamic mechanical properties including elastic modulus (E), bulk modulus (K), shear modulus (µ) and Poisson's ratio (ν). The P and S wave velocities for the selected rock types varied in the ranges of 2.43-4.61 km s^-1 and 1.43-2.41 km h^-1, respectively. Furthermore, it was observed that the P wave velocity was always greater than the S wave velocity, and this confirmed the first arrival of P waves to the sensor. According to the experimental results, the dynamic E value is generally higher than the static E value obtained by unconfined compressive strength tests.

[Inhibitory effect of migration-inducing gene-7-shRNA recombinant retrovirus combined with endostatin on growth and metastasis of hepatoma xenograft]

Objective: To investigate the inhibitory effect of migration-inducing gene-7(Mig-7)interfered with retrovirus-mediated RNA(shRNA)combined with recombinant human endostatin(ES)on the growth and metastasis of subcutaneous xenograft of human hepatoma cells in nude mice. Methods: Two Mig-7-mRNA oligonucleotide sequences(Mig-7-shRNA-1 and Mig-7-shRNA-2)and one sequence as a negative control(Mig-7-shRNA-N)were designed. The specific Mig-7-shRNA recombinant retrovirus expression vector plasmid was constructed and used for the transfection of human hepatoma MHCC-97H cells with high expression of Mig-7. The subcutaneous xenograft tumor model of human hepatocellular carcinoma(HCC)in nude mice was established, and according to the condition of transfection and administration, the nude mice were divided into pSIREN-M1 group, pSIREN-MN group, ES group, and pSIREN-M1+ES group. The xenograft tumor volume, mass, and metastasis were compared between groups. Immunohistochemistry was used to observe the formation of vasculogenic mimicry(VM)in xenograft tumor and the difference in tumor microvascular density(MVD), and Western blot was used to measure the expression of Mig-7 and vascular endothelial growth factor(VEGF)in each group. A one-way analysis of variance was used for comparison between groups, and the Fisher's exact test was used for comparison of continuous data between groups. Results: Compared with the pSIREN-MN group, the pSIREN-M1 group had significantly lower xenograft tumor volume, mass, and metastasis rate, Mig-7 expression, and formation of VM(P < 0.05), as well as significantly higher VEGF expression and MVD(P < 0.05). Compared with the pSIREN-MN group, the ES group had significantly lower xenograft tumor volume, mass, and metastasis rate, VEGF expression, and MVD(P < 0.05), as well as significantly higher Mig-7 expression and formation of VM(P < 0.05). Compared with the pSIREN-M1 group and the ES group, the pSIREN-M1+ES group had significantly lower xenograft tumor volume, mass, and metastasis rate, Mig-7 expression, formation of VM, VEGF expression, and MVD(P < 0.05). Conclusion: Mig-7-shRNA recombinant retrovirus combined with ES has a better inhibitory effect on the growth and metastasis of HCC xenograft tumor than Mig-7-shRNA recombinant retrovirus or ES alone. The anti-tumor angiogenesis therapy alone, which targets vascular endothelial cells in vivo, has a limited effect, since it may promote the formation of VM.

[Echocardiographic features of sinus of Valsalva aneurysm extending into left ventricle]

OBJECTIVE

To observe image features of sinus of Valsalva aneurysm (SVA) extending into left ventricle by echocardiography.

METHODS

Echocardiographic features of 5 cases of SVA extending into left ventricle and underwent surgery at Union Hospital from July 1995 to September 2015 were reviewed retrospectively and image and surgical findings were compared. A total of 4 patients were diagnosed by conventional and 3D echocardiography before surgery, and 1 patient was diagnosed by conventional echocardiography.

RESULTS

The origin, extending position, rupture status, complications of the SVA and associated cardiovascular lesions determined by echocardiography were entirely consistent with surgical findings in all cases, with the exception of one failed diagnosis of hypoplasty of an adjacent aortic cusp. Besides the common features of SVA, echocardiographic features of SVA extending into left ventricle included a thin-walled saccular lesion arising from the aortic root in continuation with the aortic annulus, with significant morphological changes and movement. Moreover, following features were observed: very low origin of the saccular lesion arising between the sinus base and the aortic annulus; the aneurysm going back and forth between the aortic root and the left ventricular outflow tract in 4 cases with an intact interventricular septum, and between the left ventricle and the right ventricle through the septal defect in another case complicated by a huge ventricular septal defect; diastolic shunt into the left ventricle when ruptured; displacement of the adjacent aortic annulus due to compression of aneurismal origin and prolapse of both aortic valve and annulus observed in all cases, resulting in a severe aortic regurgitation; obstructions of the left ventricular outflow tract due to the space-occupying effect were also found in 2 cases.

CONCLUSION

The SVA extending into left ventricle has distinguished echocardiographic characteristics, which could be accurately diagnosed either by conventional or real-time 3D echocardiography.