Degradation of antibiotic norfloxacin in aqueous solution by visible-light-mediated C-TiO2 photocatalysis

A visible-light-mediated C-TiO(2) photocatalytic process (Vis/C-TiO(2)) was employed to degrade antibiotic norfloxacin. The influences of catalyst dosage, initial probe compound concentration and solution pH levels on the decay performance and reaction kinetics were investigated and optimized. Based on the experimental results, an equation was established to predict the observed rate constant under neutral pH. In addition, the decay rate was accelerated under weak alkali in the presence of moderate OH(-) anions. Hydroxyl radical was confirmed to play a major role in the Vis/TiO(2) process, where in the presence of OH quencher and electron acceptor, retardation and improvement were found respectively. Furthermore, an original schematic diagram describing the surface property of C-TiO(2) was built and further verified, in which, NH(4)(+) cations normally served as hole scavengers showed a negligible effect because the adsorbed OH(-) formed a barrier for NH(4)(+) ions to approach the holes, and the F(-) anions presented a significant suppression on norfloxacin decay due to the formation of hydrogen bond (OH⋯F) around the C-TiO(2) surface. Besides, the recycling and sedimentation tests justified that the Vis/C-TiO(2) process is a cost-effective and feasible way for wastewater treatment.

Neoadjuvant chemoradiotherapy and multivisceral resection for primary locally advanced adherent colon cancer: a single institution experience

BACKGROUND

Although there is an extensive body of literature on the role of neoadjuvant chemoradiotherapy (CRT) in the management of rectal cancer, its role in primary locally advanced adherent colon cancer (LAACC) is unclear.

OBJECTIVE

To analyzed the outcomes of neoadjuvant CRT and multivisceral resection in the management of LAACC patietns.

METHODS

We retrospectively reviewed our institutional Colorectal Carcinoma Database for 33 patients with potentially resectable, non-metastatic primary LAACC who received neoadjuvant CRT followed by multivisceral resection. CRT consisted of external beam radiation (45-50 Gy in 25 daily fractions) and concurrent 5-FU infusion (225 mg/m(2)/day).

RESULTS

There were 21 males and 12 females. Median age was 64 (31-83) and median follow-up was 36 months. All patients had microscopically clear resection margins (R0). Complete pathologic response was documented in 1 patient (3%) and 66% had ypT4b disease. Post-operative complications were observed in 36% of patients with no 30-day mortality. The 3-year overall survival and 3-year disease-free survival were 85.9% and 73.7% respectively. Two patients developed a local recurrence.

CONCLUSIONS

Neoadjuvant CRT and en-bloc multivisceral resection may result in high rates of R0 resection and excellent local control with acceptable morbidity and mortality in selected patients with LAACC.

One-step solvothermal synthesis of Fe3O4@C core-shell nanoparticles with tunable sizes

We report the synthesis of Fe3O4@C core-shell nanoparticles (FCNPs) by using a facile one-step solvothermal method. The FCNPs consisted of Fe3O4 particles as the cores and amorphous uniform carbon shells. The content of Fe3O4 is up to 81.6 wt%. These core-shell nanoparticles are aggregated by primary nanocrystals with a size of 10-12 nm. The FCNPs possess a hollow interior, high magnetization, excellent absorption properties and abundant surface hydroxyl groups. A possible growth mechanism of the FCNPs is proposed. The role of glucose in regulating the grain size and morphology of the particles is discussed. The absorption properties of the FCNPs towards Cr(VI) in aqueous solution is investigated. We demonstrate that the FCNPs can effectively remove more than 90 wt% of Cr(VI) from aqueous solution.

Photocatalytic oxidation of monuron in the suspension of WO3 under the irradiation of UV-visible light

A comprehensive study of the degradation of monuron, one of the phenylurea herbicides, was conducted by UV-Vis/WO(3) process. It was found that hydroxyl radicals played a major role in the decay of monuron while other radicals (e.g. superoxide) and hole might also contribute to the decomposition of monuron. The oxidation path likely plays a major role in the generation of hydroxyl radicals. The effects of initial pH level, initial concentration of monuron, and inorganic oxidants on the performance of UV-Vis/WO(3) process were also investigated and optimized. Comparison between monuron decay pathways by UV-Vis/WO(3) and UV/TiO(2) was conducted. The decay mechanisms, including N-terminus demethylation, dechlorination and direct hydroxylation on benzene ring, were observed to be involved in the oxidation of monuron in these two processes. Sixteen intermediates were identified during the photodegradation of monuron and degradation pathways were proposed accordingly.

Comparison of acute toxicity in patients treated with a 4-field box or IMRT to deliver elective pelvic nodal irradiation for localized high-risk prostate cancer

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Background: To deliver elective pelvic nodal irradiation (EPNI), a 4-field box (4FB) has been a common technique. More recently, there are increasing reports of using IMRT to deliver EPNI. Even though studies show a clear dosimetric benefit to bowel and bladder, there is a lack of good data demonstrating decreased toxicity with the use of IMRT in this setting.

Methods: From 2004-2010, 230 patients with localized high risk prostate cancer were enrolled into 3 sequential prospective phase I/II trials of delivering EPNI (45 Gy) along with a concomitant hypofractionated IMRT boost to the prostate (67.5 Gy total) in 25 fractions over 5 weeks time. All patients were to receive 3 years of adjuvant androgen deprivation. During the accrual period, the method used to deliver the EPNI portion of the treatment changed as new literature emerged about target volumes for EPNI. The 3 methods used to deliver EPNI in this large cohort were 1) 4FB, 2) IMRT with 2cm CTV margins around the pelvic vessels as suggested by Shih et al (IMRT-Shih), and 3) IMRT with nodal volumes as suggested by RTOG (IMRT-RTOG). Common Terminology Criteria for Adverse Events v3.0 was used to assess acute toxicity prospectively during treatment and then at 3 months.

Results: For EPNI, 94 patients were treated with a 4FB, 53 were treated with IMRT-Shih, and 83 were treated with IMRT-RTOG. There were no acute grade 3 GI toxicities. Patients in the 4FB group had higher rates of acute grade ≥ 2 proctitis compared to the IMRT-Shih and IMRT-RTOG groups (16.0% vs 2.0% vs 2.4%, p=0.0009). The 4FB group also had higher rates of grade ≥ 2 flatulence compared to the 2 other IMRT groups (17.0% vs 7.6% vs 0%, p<0.0001). With regards to acute GU toxicities, patients in the 4FB group had higher rates of grade ≥ 3 urinary frequency compared to the 2 other IMRT groups (5.3% vs 0% vs 0%, p=0.027).

Conclusions: In this non-randomized comparison, IMRT resulted in statistically significant decreases in acute proctitis, flatulence, and urinary frequency when compared to a 4FB technique to deliver EPNI in localized high risk prostate cancer. Analysis for possible confounding factors will be performed.

Degradation of 2,4,5-trichlorophenoxyacetic acid by a novel Electro-Fe(II)/Oxone process using iron sheet as the sacrificial anode

A novel electrochemically enhanced advanced oxidation process for the destruction of organic contaminants in aqueous solution is reported in this study. The process involves the use of an iron (Fe) sheet as sacrificial anode and a graphite bar as cathode. In the oxidation process, once an electric current is applied between the anode and the cathode, a predetermined amount of Oxone is added to the reactor. Ferrous ions generated from the sacrificed Fe anode mediate the generation of highly powerful radicals (SO(4)(•-)) through the decomposition of Oxone. The coupled process of Fe(II)/Oxone and electrochemical treatment (Electro-Fe(II)/Oxone) was evaluated in terms of 2,4,5-Trichlorophenoxyacetic acid degradation in aqueous solution. Various parameters were investigated to optimize the process, including applied current, electrolyte and Oxone concentration. In addition, low solution pH facilitates the system performance due to the dual effects of weak Fenton reagent generation and persulfate ions generation, whereas the system performance was inhibited at basic pH levels through non-radical self-dissociation of Oxone and the formation of ferric hydroxide precipitates. Furthermore, the active radicals involved in the Electro-Fe(II)/Oxone process were also identified. The Electro-Fe(II)/Oxone process demonstrates a very high 2,4,5-T degradation efficiency (over 90% decay within 10 min), which justifies the novel Electro-Fe(II)/Oxone a promising treatment process for herbicide removal in water.

Degradation of a xanthene dye by Fe(II)-mediated activation of Oxone process

A powerful oxidation process using sulfate radicals activated by transition metal mediated Oxone process has been evaluated in depth by monitoring the degradation of a xanthene dye Rhodamine B (RhB) in aqueous solution. Ferrous ion was chosen as the transition metal due to its potential catalytic effect and wide availability in dyeing industrial effluent. The effects of parameters including reactant dosing sequence, Fe(II)/Oxone molar ratio and concentration, solution pH, and inorganic salts on the process performance have been investigated. Total RhB removal was obtained within 90 min under an optimal Fe(II)/Oxone molar ratio of 1:1. The RhB degradation was found to be a two-stage kinetics, consisting of a rapid initial decay and followed by a retarded stage. Additionally, experimental results indicated that the presence of certain anions had either a positive or negative effect on the process. The inhibitory effect in the presence of SO(4)(2-) was elucidated by a proposed formula using Nernst equation. Furthermore, dye mineralization in terms of TOC removal indicates that stepwise addition of Fe(II) and Oxone can significantly improve the process performance by about 20%, and the retention time required can be greatly reduced comparing with the conventional one-off dosing method.

Mask Technology For X-Ray Nanolithography

In this report we describe a system of technologies we have developed for fabricating, patterning, and replicating x-ray masks with linewidths as fine as 50 nm (0.05 μm). This effort has evolved into a fairly routine service supporting a growing community of researchers at MIT interested in fabricating sub-micron and nanometer scale structures and devices. Strong, transparent, silicon-rich nitride (SiN) membranes bonded to optically-flat Pyrex rings and patterned with gold absorbers form the basic x-ray mask structure. We have recently completed the installation of a vertical thermal reactor (VTR) for the deposition of SiN coatings. Results indicate superb film uniformity, decreased defect counts, and increased strength over previously available nitrides. Patterning of the masks is performed at an off-site location by electron-beam lithography followed by development and gold electroplating at MIT. We describe a new fountain plating bath and mask chuck which allows us to obtain clean, uniform gold films of low stress. Once completed, the so-called “master” masks are replicated onto new x-ray mask substrates which are then processed into “daughter” masks. The resulting polarity-reversed patterns are required in order to achieve the desired pattern in positive resist when printed onto substrates. We will describe our in-house built x-ray aligner which features a high-power electron bombardment source and SiN vacuum isolation window to achieve exposures in a helium environment.

Comparison of clinical results of surgical treatment for unstable distal clavicle fractures by transacromial pins with and without tension band wire

BACKGROUND

An unstable distal clavicle fracture (Neer type II) is an indication that surgical intervention is required. Numerous treatment options have been introduced, but there is no gold standard.

METHODS

We report on our experience of 29 consecutive cases, between 2002 and 2008, of acute unstable distal clavicle fracture (Neer type II) and operative treatment using transacromial pins with tension band wire, and compare the use of this treatment with that of traditional transacromial Kirschner wire fixation. All patients were given postoperative radiological and clinical evaluations at 4, 8 and 12 weeks, and then the final clinical outcome, based on the University of California at Los Angeles shoulder rating, was recorded.

RESULTS

The fractures in both groups were clinically united at a mean follow-up of 8.62 weeks (range, 6-20 weeks). Six of the 14 patients (43%) with traditional transacromial Kirschner wire fixation suffered from pin migration and discomfort of skin erosion, 3 had residual displacement, and 1 had a recurrent fracture. In contrast, only 1 patient (7%) in the tension band wire group had residual displacement and pin migration causing skin tenting, and this was made comfortable by pin removal. The complication rate and the University of California at Los Angeles shoulder rating were significantly different between the 2 groups.

CONCLUSION

Transacromial pins with tension band wire provide superior fixation for a type 2 fracture of the distal clavicle, compared with traditional transacromial Kirschner wire fixation.

Degradation of linuron by UV, ozonation, and UV/O(3) processes--effect of anions and reaction mechanism

A comprehensive study of the degradation of linuron, one of the phenylurea herbicides, was conducted by using different treatment processes including UV, ozonation and UV/O(3). The effect of various anions on the performance of ozonation has been examined. N-terminus demethoxylation, photohydrolysis with or without dechlorination, and N-terminus demethylation have been found to be the major mechanisms in the linuron decay under the irradiation of UV at 254 nm while N-terminus demethoxylation, dechlorination and hydroxylation on benzene ring was observed to be involved in the ozonation process. Eight new intermediates were identified in UV process in this study compared with previous studies. Different decay pathways were proposed based on the identified intermediates in the three studied processes. UV/O(3) has demonstrated the best performance among these three processes in terms of LNR decay, mineralization, dechlorination and de-nitrogenation.