[Analysis of the long-term outcomes of different secondary surgeries for recurrent stress urinary incontinence after Burch colposuspension]

Objective: To analyze the long-term outcomes of different secondary surgeries in women with recurrent stress urinary incontinence (SUI) after Burch colposuspension. Methods: Between February 2004 to February 2010, five women with recurrent SUI after Burch colposuspension in Peking Union Medical College Hospital were retrospectively followed up, and the long-term outcomes of secondary surgeries were analyzed. Subjective cures of Burch colposuspension and secondary surgeries were assessed by patients' self-reported incontinence symptoms and patient global impression of improvement questionnaire; objective cure, improvement or failure were determined by 1-hour pad test. Results: Three women underwent tension-free vaginal tape-retropubic (TVT) as the secondary surgery, one underwent tension-free vaginal tape-obturator (TVT-O), and one underwent single-incision tension-free vaginal tape-Secur (TVT-Secur). The follow-up period of five women was (14.6±2.4) years (range: 10.8 to 16.9 years). Three women undergoing TVT secondary surgery were subjectively cured; while the other two women undergoing TVT-O or TVT-Secur were not subjectively cured, but the woman undergoing TVT-O was objectively improved. Conclusions: It is feasible for women with recurrent SUI after Burch colposuspension to receive the secondary surgery. Our limited data suggests that TVT could be considered.

[China guideline for the screening, early detection and early treatment of gastric cancer (2022, Beijing)]

Gastric cancer (GC) is a major digestive tract malignancy in China, which seriously threatens the health of Chinese population. A large number of researches have demons-trated that screening, early detection and early treatment are effective in reducing the incidence and mortality of GC. The development of the guideline for GC screening, early detection and early treatment in line with epidemic characteristics of GC in China will greatly promote the homogeneity and standardization, and improve the effect of GC screening. This guideline was commissioned by the Bureau of Disease Control and Prevention of the National Health Commission. The National Cancer Center of China initiated and convened a working group comprising multidisciplinary experts. Following the World Health Organization Handbook for Guideline Development, this guideline combined the most up-to-date evidence of GC screening, China's national conditions, and practical experience in cancer screening. This guideline provided evidence-based recommendations with respect to the screening population, technology and procedure management, aiming to improve the effect of GC screening and provide scientific evidence for the GC prevention and control in China.

[China guideline for the screening, early detection and early treatment of esophageal cancer (2022, Beijing)]

Esophageal cancer (EC) is a major digestive tract malignancy in China, which seriously threatens the health of Chinese population. A large number of researches have demonstrated that screening and early detection are effective in reducing the incidence and mortality of EC. The development of the guideline for EC screening and early detection in line with epidemic characteristics of EC in China will greatly promote the homogeneity and standardization, and improve the effect of EC screening. This guideline was commissioned by the Bureau of Disease Control and Prevention of the National Health Commission. The National Cancer Center of China initiated and convened a working group comprising multidisciplinary experts. Following the World Health Organization Handbook for Guideline Development, this guideline combined the most up-to-date evidence of EC screening, China's national conditions, and practical experience in cancer screening. This guideline provided evidence-based recommendations with respect to the screening population, technology and procedure management, aiming to improve the effect of EC screening and provide scientific evidence for the EC prevention and control in China.

[Effect of the pessary treatment on anxiety disorder in patients with symptomatic pelvic organ prolapse]

Objective: To evaluate the effect of the pessary treatment on general anxiety disorder in patients with symptomatic pelvic organ prolapse (POP). Methods: Between December 2018 and January 2020, 213 patients who received the pessary treatment for symptomatic POP in the Peking Union Medical College Hospital (PUMCH) were enrolled in this prospective observational study. Accepting the pessary successfully means that the patient keeping the pessary for 2 weeks were satisfied with it and willing to use it afterwards, or means that the patient having changed a new pessary and keeping it for 2 weeks were satisfied with it and willing to use it afterwards. The questionnaire General Anxiety Disorder-7 (GAD-7) was used to assess the anxiety state of POP patients, including 163 patients who accepted the pessary treatment successfully and 50 patients who failed, before and after the pessary treatment. A score of 10 or more was considered as the moderate or severe anxiety and defined as the anxiety disorder. Patients who accepted the pessary treatment successfully were followed up for 3 months. Results: Before the treatment, the prevalence of anxiety disorders was 20.9% (34 out of 163) for those patients accepting the pessary and that was 20.0% (10 out of 50) for those patients who failed in keeping the pessary, the difference of which were not statistically significant (P=0.896). The difference of demographic data and clinical characteristics between the anxiety disorder group and the non-anxiety disorder group were not statistically significant (P>0.05). After 3 months of the pessary treatment for those patients using the pessary treatment, the prevalence of anxiety disorders dropped to 3.7% (6/163) from 20.9% (P<0.001). The GAD-7 score of patients with anxiety disorders decreased from a median of 16.0 (12.5, 21.0) before the treatment to 1.0 (0, 4.0) after the treatment, and the difference was statistically significant (P<0.001). Conclusion: Around 20% POP patients receiving pessary treatment had the moderate or severe general anxiety disorder. After 3 months of using the pessary treatment, the prevalence of anxiety disorders in POP patients had dropped significantly.

[COVID-19 epidemic and its characteristics in Heilongjiang province]

Objective: To describe the COVID-19 epidemic and its characteristics in Heilongjiang province, and provide evidence for the further prevention and control of COVID-19 in the province. Methods: The information of COVID-19 cases and clusters were collected from national notifiable disease report system and management information system for reporting public health emergencies of China CDC. The Software's of Excel 2010 and SPSS 23.0 were applied for data cleaning and statistical analysis on the population, time and area distributions of COVID-19 cases. Results: On January 22, 2020, the first confirmed case of COVID-19 was reported in Heilongjiang. By March 11, 2020, a total of 482 cases domestic case of COVID-19, The incidence rate was 1.28/100 000, the mortality rate was 2.70% (13/482) in 13 municipalities in Heilongjiang. There were 81 clusters of COVID-19, The number of confirmed cases accounted for 79.25% (382/482) of the total confirmed cases and 12 cases of deaths. The family clusters accounted for 86.42% (70/81). Compared with the sporadic cases, the mortality rate, proportion of elderly cases aged 60 or above and severe or critical cases of clinical classification were all higher in the clusters especially the family clusters, but the differences were not significant (P>0.05). There were 34 clusters involving more than 5 confirmed cases accounted for 41.98% (34/81) of the total clusters, the involved cases accounted for 68.31% (261/382) of the total cases of clusters. There were significant differences in age distribution of the cases among the case clusters with different case numbers. In the clusters involving 6-9 cases, the proportion of cases aged 65 years or above was more (26.53%, 39/147). Conclusions: The incidence rate of COVID-19 was relatively high and the early epidemic was serious in Heilongjiang, The number of cases was large in clusters especially family clusters.

[Distribution and Removal of Polycyclic Aromatic Hydrocarbons and Their Derivatives in SBR/MBBR Process]

While polycyclic aromatic hydrocarbons (PAHs) are an important persistent toxic organic contaminant, the toxicities of substituted polycyclic aromatic hydrocarbons (SPAHs) are much higher than PAHs. Water and sludge samples were collected from the Qingdao Chengyang Sewage Treatment Plant (STP). The distribution and removal of 16 PAHs and nitro-PAHs (NPAHs), methyl-PAHs (MPAHs), and oxy-PAHs (OPAHs) in the SBR/MBBR process were analyzed. The results showed that 16 PAHs and 13 SPAHs were detected. In the influent water, the total concentrations of PAHs and SPAHs were 3835.14 ng·L^-1 and 6889.46 ng·L^-1, respectively, which were much higher than those of STPs in other regions. In the effluent, the total concentrations of PAHs and SPAHs were 1148.18 ng·L^-1 and 1724.57 ng·L^-1, respectively, and the removal rates were up to 70.06% and 74.97%, respectively. The SBR/MBBR process presented a more effective removal capacity for PAHs and SPAHs. The removal of PAHs was mainly by the biodegradation of low-ring polycyclic aromatic hydrocarbons (LMW-PAHs)in the aqueous phase; while the removal of PAHsin the particle phase mainly relied on the adsorption and precipitation of LMW-PAHs in the primary sedimentation tank and the biosorption of high-ring polycyclic aromatic hydrocarbons (HMW-PAHs) in the bio-unit. For SPAHs, the removal efficiency of MPAHs (up to 89.15%) was the best under the functions ofparticle adsorption and biodegradation. The removal rate of OPAHs was 63.36%, which was mainly removed by the adsorption of primary particles in the aqueous phase and the biosorption from the biological treatment unit in the particlephase, and the removal rate of NPAHs was 48.85% and largely occurred in the biological treatment unit. The removal mechanism of SPAHs in SBR/MBBR process was not the same. Therefore, STPs should take adequate control measures according to the distribution characteristics of PAHs and SPAHs in different treatment units. Additionally, the concentrations of PAHs and SPAHs in sludge were higher than those in the effluent. Thus, the management of PAHs and SPAHs in sludge should be improved.

Nonfunctional pancreatic endocrine tumor in the peripancreatic region in a Chinese patient with multiple endocrine neoplasia type 1

Nonfunctional pancreatic neuroendocrine tumors (NF-pNETs) in patients with multiple endocrine neoplasia type 1 (MEN1), which results from a mutation in the MEN1 gene, are commonly small, multiple tumors located in the pancreatic head and inside the pancreatic parenchyma. We herein describe a 35-year-old woman with bone pain and a 7-year history of a prolactinoma. She was clinically diagnosed with MEN1 based on the presence of the prolactinoma and parathyroid hyperplasia. Abdominal computed tomography revealed a 5-cm mass close to the splenic hilum. This soft tissue tumor, which was located outside the pancreatic parenchyma and the tissue origin of which could not be identified preoperatively, was found to be connected to the pancreatic tail. After resection, histological examination revealed a well-differentiated neuroendocrine tumor of pancreatic origin. Genetic testing revealed a heterozygous transition mutation of guanine to adenine at the coding nucleotide 133 in exon 2 (c.133G>A), resulting in an amino acid substitution of glutamic acid with lysine (E45K) in the MEN1 gene. This patient with MEN1 presented with a clinical condition involving a single non-metastatic NF-pNET located outside the pancreatic parenchyma with a missense mutation in the MEN1 gene, which could easily have been misdiagnosed as an accessory spleen.

Characteristics of two novel cold- and salt-tolerant ammonia-oxidizing bacteria from Liaohe Estuarine Wetland

To achieve a better contaminant removal efficiency in a low-temperature and high-salt environment, two novel strains of cold- and salt-tolerant ammonia-oxidizing bacteria (AOB), i.e., Ochrobactrum sp. (HXN-1) and Aquamicrobium sp. (HXN-2), were isolated from the surface sediment of Liaohe Estuarine Wetland (LEW), China. The optimization of initial ammonia nitrogen concentration, pH, carbon-nitrogen ratio, and petroleum hydrocarbons (PHCs) to improve the ammonia-oxidation capacity of the two bacterial strains was studied. Both bacterial strains showed a high ammonia nitrogen removal rate of over 80% under a high salinity of 10‰. Even at a temperature as low as 15°C, HXN-1 and HXN-2 could achieve an ammonia nitrogen removal rate of 53% and 62%, respectively. The cold- and salt-tolerant AOB in this study demonstrated a high potential for ammonia nitrogen removal from LEW.

A novel Al matrix composite reinforced by nano-AlNp network

In pursuit of lightweighting of automobiles and low emission of transportation, the efforts to develop high-strength, heat-resistant and fatigue-resistant Al alloys and/or composites have been ongoing. Here we report a novel Al matrix composite with ultrahigh strength reinforced by a three dimensional network of nano-AlN particles for the first time. The in-situ synthesized AlN particles are connected by twinning bonding chains and built up a three dimensional network strengthening Al matrix enormously like the skeleton to human body. The composite containing 16.4wt.% AlN particles shows excellent properties: the ultimate tensile strengths can be up to 518MPa at room temperature and 190MPa at 350 °C. This peculiar performance results from the novel spatial distribution of nano-scale AlN particles. Our findings in this work would help to develop a potential candidate for high-performance heat resistance light-metal based materials.

Enhanced biodegradation of pyrene and indeno(1,2,3-cd)pyrene using bacteria immobilized in cinder beads in estuarine wetlands

Two strains (Pseudomonas taiwanensis PYR1 and Acinetobacter baumannii INP1) were isolated from PAH-contaminated Liaohe estuarine wetland using enrichment. The cells of PYR1 and INP1 were immobilized in cinder beads for pyrene and indeno(1,2,3-cd)pyrene biodegradation in wetland. Biodegradation of pyrene and indeno(1,2,3-cd)pyrene in soils from wetland was carried out in pots using free cells as well as those immobilized in cinder beads to ascertain the role of bioaugmentation. Supported by the cinder beads, the immobilized cells degraded 70.7% and 80.9% of pyrene and indeno(1,2,3-cd)pyrene respectively after 30 days. While the free cells degraded only 58.2% and 55.3%. Additionally, microbial analysis with high-throughput sequencing revealed the changes of microbial communities in soil without and with cinder beads immobilized with strains. The result indicated that Gammaproteobacteria were dominant PAH-degrading groups during bioaugmentation. This effective approach can be used to treat other PAH-contaminated wetlands by immobilizing different species of bacteria in cinder beads.

Outcomes and patterns of secondary relapse in platinum-sensitive ovarian cancer: implications for tertiary cytoreductive surgery

AIM

To evaluate the outcomes and patterns of patients with secondary relapsed ovarian cancer.

METHODS

A retrospective study was conducted. The cases comprised 83 patients who underwent tertiary cytoreductive surgery (TCS) followed by chemotherapy, whereas the controls consisted of 76 patients who received chemotherapy alone.

RESULTS

The median survival was 20 months in 159 patients. Patients with microscopic residual disease after TCS had a median survival of 32.9 months compared with 14.6 months in those with macroscopic residual disease [hazard ratio (HR), 2.82; P = 0.001) and 15.0 months in patients with chemotherapy alone (HR, 2.23; P = 0.001). When stratified by a progression-free interval (PFI) after secondary cytoreduction (SCR), TCS showed no benefit in patients with a PFI ≤12 months or a PFI >12 months compared with those with chemotherapy alone. TCS improved survival in patients with recurrent disease in the pelvis compared with those with recurrent disease in the middle or upper abdomen, with a median survival of 34.9 months and 14.6 months, respectively (HR, 2.94; P = 0.010). However, TCS was not a survival determinant by multivariate analysis. A multivariate analysis identified a PFI after SCR (≤12 mos vs. >12 mos; HR, 2.34; 95% CI, 1.29-4.24; P = 0.005), mesenteric lymph node metastasis at SCR (yes vs. no; HR, 4.18; 95% CI, 1.93-9.03; P < 0.001) and treatment arms at secondary relapse (chemotherapy alone vs. TCS; HR, 1.56; 95% CI, 1.03-2.38; P = 0.037) as independent predictors of survival.

CONCLUSIONS

Limited survival benefit from tertiary cytoreductive surgery was observed in patients with platinum-sensitive secondary relapsed ovarian cancer.

Emergency caudate lobectomy for ruptured hepatocellular carcinoma with multiple primary cancers

We report a case of metachronous multiple primary malignancies involving both rectum and liver with colonic metastasis from hepatocellular carcinoma (HCC) through hematogenous pathway. A 72-year-old woman was admitted to the emergency department with right upper abdominal pain for 4 h. Considering her surgical history of Mile’s procedure plus liver resection for rectal cancer with liver metastasis three years ago and the finding of urgent computed tomography scan on admission, the preoperative diagnosis was spontaneous rupture of rectal liver metastasis located in caudate lobe and colonic metastasis from rectal cancer. The patient underwent an emergency isolated caudate lobectomy at a hemorrhagic shock status. Pathology reported a primary HCC in the caudate lobe and colonic metastasis of HCC with tumor embolus in the surrounding vessels of the intestine. No regional lymph node involvement was found. It is hypothesized that HCC may disseminate hematogenously to the ascending colon, thus making it a rare case.

Prognostic factors and treatment comparison in early-stage small cell carcinoma of the uterine cervix

Small cell carcinoma of the uterine cervix (SCCUC) is rare and its biologic behavior is aggressive. To analyze prognostic factors and determine optimal therapy in patients with International Federation of Gynecology and Obstetrics (FIGO) stage IB1-IIA SCCUC, we retrospectively reviewed 96 patients (14 patients treated in our center and 82 patients identified by a search on PubMed) treated with radical surgery (SU), surgery plus adjuvant chemotherapy (SU+Chemo), or surgery plus adjuvant chemotherapy and radiotherapy (SU+Chemo+RT) between 1990 and 2010. Of the 96 patients, 11 patients were treated with SU, 33 with SU+Chemo, and 52 with SU+Chemo+RT. The 5-year survival rate for the 96 patients was 45%. A total of 6% (2/32) of patients had local recurrence, 75% (24/32) had distant metastases, and 19% (6/32) had both. The 5-year survival rate in stage IB1 and IB2-IIA disease was 58 and 34%, respectively (P=0.049). For patients with and without lymph node metastases (LNM), survival was 33 and 60%, respectively (P=0.045). Patients with inner 1/3 stromal invasion had a better survival than those with deep stromal invasion (DSI) (100 vs. 34%, P=0.003). Survival was not significantly different in patients treated with the above three modalities, albeit treatment selection was related to LNM (P=0.000) and DSI (P=0.027). Thus, FIGO stage, LNM and DSI are significant predictors of survival. Adjuvant therapy after SU has not improved survival compared with surgery alone. Thus, newer multimodality therapy should be evaluated.

Predictors of survival in patients with recurrent ovarian cancer undergoing secondary cytoreductive surgery based on the pooled analysis of an international collaborative cohort

BACKGROUND

This study aims to identify prognostic factors and to develop a risk model predicting survival in patients undergoing secondary cytoreductive surgery (SCR) for recurrent epithelial ovarian cancer.

METHODS

Individual data of 1100 patients with recurrent ovarian cancer of a progression-free interval at least 6 months who underwent SCR were pooled analysed. A simplified scoring system for each independent prognostic factor was developed according to its coefficient. Internal validation was performed to assess the discrimination of the model.

RESULTS

Complete SCR was strongly associated with the improvement of survival, with a median survival of 57.7 months, when compared with 27.0 months in those with residual disease of 0.1-1 cm and 15.6 months in those with residual disease of >1 cm, respectively (P<0.0001). Progression-free interval (≤23.1 months vs >23.1 months, hazard ratio (HR): 1.72; score: 2), ascites at recurrence (present vs absent, HR: 1.27; score: 1), extent of recurrence (multiple vs localised disease, HR: 1.38; score: 1) as well as residual disease after SCR (R1 vs R0, HR: 1.90, score: 2; R2 vs R0, HR: 3.0, score: 4) entered into the risk model.

CONCLUSION

This prognostic model may provide evidence to predict survival benefit from secondary cytoreduction in patients with recurrent ovarian cancer.

Performance of a sulfidogenic bioreactor and bacterial community shifts under different alkalinity levels

The performance of a sulfidogenic bioreactor and the response of bacterial populations to influent alkalinity changes were investigated. The bioreactor reached 40% of sulfate removal efficiency (SRE) with 0 mg l(-1) of alkalinity, and single-stranded conformation polymorphism profiles showed that some members of Bacteroides, Dysgonomonas, Sporobacter, Quinella, and Citrobacter became dominant populations. 16S rRNA gene library analysis indicated that the Actinobacteria group increased from 0% in seed to 23% in sludge. An increase in alkalinity to 1300 mg l(-1) led to a rapid increase of SRE to 65% and changes in the bacterial community. Sequences representing Dysgonomonas, Raoultella, Kluyvera, and Phascolarctobacterium were now found. When alkalinity was deceased to 0 mg l(-1), SRE dropped and the bands representing Raoultella, Kluyvera, and Phascolarctobacterium disappeared, while bands representing Clostridium appeared. A second cycle of low/high alkalinity did not result in obvious changes to the bacterial community. These results indicate that the sulfidogenic bioreactor favored higher influent alkalinity and that the different functional microbial populations responded well to the alkalinity changes.

[Studies on nitrobacteria and nitrification in Liaohe estuary wetland sediments]

Nitrobacteria, nitrification and its impact factors were discussed based on the method of on-site incubation and laboratory simulation in Liaohe estuary wetland sediments in June and August 2009, respectively. The results showed that the number of ammonia-oxidizing bacteria (AOB) ranged from 0.54 x 10(4) to 5.69 x 10(4) cells x g(-1) with an average of (2.21 +/- 2.32) x 10(4) cells x g(-1) in June and ranged from 1.90 x 10(4) to 7.90 x 10(4) cells x g(-1) with an average of (3.61 +/- 2.87) x 10(4) cells x g(-1) in August. The potential nitrification rates ranged from 9.72 to 16.45 mmol x (m2 x h)(-1) with an average of (12.54 +/- 3.14) mmol x (m2 x h)(-1) in June and ranged from 14.66 to 24.62 mmol x (m2 x h)(-1) with an average of (18.71 +/- 4.21) mmol x (m2 x h)(-1) in August. The net nitrification rates were 0.41 mmol x (m2 x h)(-1) in June and ranged from 0.20 to 0.53 mmol x (m2 x h)(-1) with an average of (0.35 +/- 0.16) mmol x (m2 x h)(-1) in August. The potential nitrification rates were apparently higher than the net nitrification rates. The AOB abundance and nitrification rates were all higher in August than in June. Ammonia concentration in the overlying water, pH, organic matter, total nitrogen content, total phosphorus content, ammonia nitrogen content and the number of AOB in sediments were the main environmental impact factors on nitrification by SPSS 13.0 statistical analysis (p < 0.05), and it also showed ammonia concentration in the overlying water, total phosphorus content and ammonia nitrogen content in sediments were key impact factors on nitrification by partial correlation analysis. The flux of transformed ammonium into nitrate by nitrification process was 1.14 x 10(5) kg per day, suggesting that nitrification was important on nitrogen cycle in Liaohe estuary wetland sediments.

The role of secondary cytoreductive surgery for recurrent mucinous epithelial ovarian cancer (mEOC)

BACKGROUND

Mucinous epithelial ovarian cancer (mEOC) may exhibit a distinct biological behavior in epithelial ovarian cancer (EOC). The role of secondary cytoreductive surgery was evaluated in patients with recurrent mEOC, and the prognosis was assessed.

METHODS

Twenty-one patients with stages IIc to IV mEOC who experienced disease recurrence and received secondary cytoreductive surgery at Fudan University Cancer Hospital between Jan. 1997 and Dec. 2005 were retrospectively reviewed. Survival curves were generated using the Kaplan-Meier method and the significant comparison of survival rate was estimated by the log-rank test.

RESULTS

The median progression-free interval (PFI) was 14 months (range, 5-46 months) after the first cytoreduction. Seven patients (33%) who received secondary cytoreductive surgery were optimally cytoreduced with residual disease less than or equal 1cm, and the other 14 patients (67%) underwent suboptimal surgical cytoreduction. The overall median survival time was 27 months (range, 8-64 months). The median survival time after recurrence was 10 months (range, 3-32 months). There was no significant statistical difference in median survival between patients with optimal and suboptimal secondary surgical cytoreduction, with an estimated survival of 10 months and 9.8 months, respectively (P>0.05).

CONCLUSION

Optimal primary cytoreductive surgery for advanced mEOC was very important. Once it recurs, the prognosis is very poor. Patients with recurrent mEOC should be carefully assessed before performing secondary cytoreductive surgery, as this may have limited impact on the overall survival rates.

On the Lorentz local electric field in soft-matter systems

In electric-field-responsive soft-matter systems, the suspended particles respond to the Lorentz local field (LLF), yielding abundant important phenomena. Even though the particles can easily rotate, the LLF was conventionally adopted as a quantity that is independent of rotations in the literature. In contrast, here we design an experiment to measure the LLF between two metallic spheres, one of which is rotating, and report a rotation-driven reduction. Excellent agreement between our experiment and theory reveals the role of the relaxation of dipole moments. Its relevance to biophysics, colloidal physics, and nonlinear physics is also discussed.

[Elasticity plastic filler for purification of polluted streams in situ entering lake]

The biofilm process using a new-type elasticity plastic filler was adopted in a typical polluted stream entering the Tai Lake (the Linzhuanggang). The experiments at pilot scale ran for about 0.5 years. Results show the average removal percentage of permanganate index by biofilm attached to the elasticity plastic filler is about 5.4%, the biggest removal percentage is 9.9%, the average removal percentage of NH(4+) -N is approximately 5.35%-39.91%, the biggest removal percentage of TP is 28.6%. And the bacteriological experimental results show there is the same change laws between the removal percentage of permanganate index and the numbers of heterotrophic bacteria; the numbers of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are matching with removal of NH(4+) -N.

Origin of the reduced attracting force between a rotating dielectric particle and a stationary one

Recently Tao and Lan [Phys. Rev. E. 72, 041508 (2005)] experimentally reported that the rotation of a dielectric particle can reduce significantly the attracting interparticle force between the rotating dielectric particle and a stationary one in argon gas. We develop the Gu-Yu-Hui theory of relaxation [J. Chem. Phys. 116, 24 (2002)] to account for the Tao-Lan observations. Excellent agreement between the theoretical results and the Tao-Lan experimental data shows that the reduction in the attracting interparticle force is due to the effect of charge relaxation. We also show that the relaxation time of touching rotating particles can be accurately determined with the aid of the developed theory, for which, however, the well-known Maxwell-Wagner relaxation time is no longer valid.

Response of Ferrogels Subjected to an AC Magnetic Field

When a ferrogel, which is chemically cross-linked polymer networks swollen with a ferrofluid, consisting of magnetic particles having nonlinear characteristics is subjected to an alternating current (ac) magnetic field, the magnetic response will generally consist of ac fields at frequencies of the higher-order harmonics. By using a perturbation approach, we investigate nonlinear ac responses of ferrogels, under an ac magnetic field either coupled with a dc magnetic field or not. It is shown that it is possible to detect the volume fraction and shape of particles in ferrogels by measuring such ac responses. Our results are very well understood in spectral representation and are favorably compared with the experimental observations of suspensions being beyond ferrogels.

Dynamic effects on nonlinear alternating current responses in electrorheological fluids

By using a perturbation approach, we investigate dynamic effects on nonlinear alternating current (ac) responses in electrorheological (ER) fluids under an ac or direct current electric field. We show that the dynamic effect due to a shear flow, which exerts a torque on ER particles and thus leads to the rotation of the particles about their centers, plays a significant role in the responses. Our results can be well interpreted in the dielectric dispersion spectral representation, and they offer a convenient method to determine the relaxation time and rotation velocity of ER particles by measuring the nonlinear ac responses.

Biodegradation of an endocrine-disrupting chemical, di-2-ethylhexyl phthalate, by Bacillus subtilis No. 66

A bacterial strain capable of rapidly degrading di-2-ethylhexyl phthalate (DEHP) was isolated from soil and identified as Bacillus subtilis. The organism also utilized di-butyl phthalate, di-ethyl phthalate, di-pentyl phthalate, di-propyl phthalate, and phthalic acid as sole carbon sources; and their biodegradation ratio was over 99%, when the incubation was performed for 5 days at 30 degrees C. The microorganism degraded di-2-ethylhexyl phthalate and di-butyl phthalate through the intermediate formation of mono-2-ethylhexyl phthalate and mono-butyl phthalate, which were then metabolized to phthalic acid and further by a protocatechuate pathway, as evidenced by oxygen uptake studies and GC-MS analysis. The decontamination of soil polluted with di-2-ethylhexyl phthalate by B. subtilis was investigated. Experimental results showed that the strain could degrade about 80% of 5 mM DEHP simply by adding 8% culture medium to soil, indicating that the degradation can occur even when other organisms are present.