Effect of tube size on performance of a fixed-film tubular bioreactor for conversion of hydrogen sulfide to elemental sulfur

A fixed-film continuous-flow photobioreactor was used for the removal of hydrogen sulfide from synthetic industrial wastewater and conversion of it to elemental sulfur using sixteen 150 mm length Tygon tubes as the active part of the reactor. Three different tube sizes (internal diameters (ID) 6.4, 3.2, and 1.6mm) were used to investigate the effect of tube size on reactor performance. The reactor with 1.6mm tube attained a higher sulfide loading (1451 mg/Lh) than previously reported in the literature. High bacterial concentration, light to volume ratio and intimate contact between attached bacteria and influent sulfide resulted in excellent performance of the 1.6mm tube reactor.     

Future perspectives on sustainable tribology

This paper highlights the future perspectives of sustainable tribology by examining the economic, environmental and social impact of three tribological case studies. One case study examines the sustainability and durability of micro-CHP systems looking the tribological phenomena generated within a scroll expander system. The scroll is the main part of a specific micro-CHP system and experiences wear and cavitation damage. The tribological optimization of the scroll expander improves the sustainability of the micro-CHP unit while it has a serious economic and environmental impact to the consumers and to the society in general. Another case study is focused on friction and wear performance of lifeboat launch slipways. The causes of high friction and wear during the RNLI's lifeboat launches along an inclined slipway are investigated with a view to reducing the environmental impact due to slipway panel wear and lubricant release into the marine environment. The project encompasses the sustainable design of slipway panels using design modifications based on tribological investigations to double their lifespan, while environmental and economic impact was significantly reduced by the use of biodegradable greases and water as lubricants. The final case study involves an investigation of recycled plastic materials to replace polyurethane used on skateboard wheels, scooters and similar applications. Polyurethane (PU) is difficult to recycle. With the dwindling resources and environmental problems facing the world today, recycling for both waste reduction and resource preservation has become an increasingly important aspect of sustainability. The tribological results showed that recycled polycarbonate plastic can effectively act as a substitute to polyurethane wheels. Moreover, sustainability considerations showing the environmental benefits of the use of recycled plastics over PU include reducing the CO₂ footprint by 50% and the energy consumed by 60%, among other benefits. These case studies emphasise the importance of sustainable tribology in our epoch showing that increased sustainability performance can be achieved through tribology to a significant extent in many cases, providing stability to our world and more viable long term growth to our societies.     

Clinical and prognostic aspects of adrenocortical neoplasms in childhood

BACKGROUND: A retrospective study of 54 children was undertaken to define the clinical presentation and secretory patterns of adrenal tumors and to evaluate the outcome of surgical resection and medical therapy. PROCEDURES: Different factors were studied in univariate and multivariate analysis by using the Cox proportional hazard model. RESULTS: Median age at diagnosis was 4 years. Boys and girls were affected equally. The disease was revealed by virilization (61%) or by a palpable mass (39%) with a 0.1-5.5 year delay from initial symptoms. At initial examination, we found that 76% of children were virilized. Ninety-four percent of the tested tumors secreted androgens, which were associated with glucocorticoids in 36%. Adrenal tumors in children were smaller than in adults. Half of them measured less than 10 cm. There were recurrences in 40% of children. The survival rate at 5 years was 49%, 70% if resection was microscopically complete and 7% if not (P < 0.001). CONCLUSIONS: In children, rare adrenal tumors have different diagnostic and prognostic characteristics than in adults; however, recurrences remain frequent. The efficacy of chemotherapy, mainly o,p'-DDD (Mitotane), remains to be evaluated in comparative trials.     

Instrumentation for space

The primary drivers for space instruments are the environment and survivability, support assets, delivery cost, and lack of accessibility. Survivability deals primarily with environments, such as launch and depressurization, extremes of temperature, high vacuum, radiation, and hypervelocity impacts. The cost to deployment is directly coupled to launch services, which are inherently expensive. These costs are nonlinear functions of the mass and volume of satellite payloads. The “user interfaces” for space-borne instruments are high-cost assets because they include mission operations centers, satellite hacking station(s), and ground networks. All of these issues demand high reliability     

Conservative surgical therapy for penile and urethral carcinoma

OBJECTIVES: Invasive penile and urethral tumors are traditionally treated with aggressive excision that requires involved organ and adjacent organ sacrifice. An alternative approach seeks to completely excise the tumor with adequate margins while preserving form and function of the organ. We present 6 patients who underwent such organ-sparing surgery. METHODS: Six selected cases (4 penile and 2 urethral) are presented with operative photographs and pertinent data. RESULTS: Three distal tumors of the penis were treated with excision limited to the glans with histopathologic findings of verrucous carcinoma, melanoma, and angiosarcoma. One patient with squamous cell carcinoma of the distal shaft refused partial penectomy and underwent a local wedge resection. A patient with locally advanced bulbourethral transitional cell carcinoma (TCC) refused cystourethrectomy and underwent an anterior urethrectomy and perineal urethrostomy. A 48-year-old woman with an adenocarcinoma contained in a very distal urethral diverticulum underwent simple diverticulectomy and excision of distal urethra. Postoperative voiding and sexual function were well preserved. Follow-up was 12 to 48 months. The patient with angiosarcoma died of lung metastases at 48 months with no local disease, and the patient with bulbourethral TCC developed pelvic disease at 12 months with no local recurrence and died of metastases at 25 months. CONCLUSIONS: Organ-sparing surgery is appropriate in selected patients on the basis of stage and location, high risk of distant failure, and patient disposition. Close follow-up is necessary. Comanagement with reconstructive and oncologic specialists optimizes results and outcomes.     

Production of human normal adult and fetal hemoglobins in Escherichia coli

A hemoglobin expression system in Escherichia coli is described. In order to produce authentic human hemoglobin, we need to co-express both methionine aminopeptidase and globin genes under the control of a strong promoter. We have constructed three plasmids, pHE2, pHE4 and pHE7, for the expression of human normal adult hemoglobin and a plasmid, pHE9, for the expression of human fetal hemoglobin, in high yields. The globin genes can be derived from either synthetic genes or human globin cDNAs. The extra amino-terminal methionine residues of the expressed globins can be removed by the co-expressed methionine aminopeptidase. The heme is inserted correctly into the expressed alpha- globin from our expression plasmids. A fraction (approximately 25%) of the heme is not inserted correctly into the expressed beta- or gamma- globin. However, the incorrectly inserted hemes can be converted into the correct conformation by carrying out a simple oxidation-reduction process on the purified hemoglobin molecule. We have investigated the functional properties of the expressed hemoglobins by measuring their oxygen-binding properties and their structural features by obtaining their 1H-NMR spectra. Our results show that authentic human normal adult and fetal hemoglobins can be produced from our expression plasmids in E. coli and in high yields. Our expression system allows us to design and to produce any recombinant hemoglobins needed for our research on the structure-function relationship in hemoglobin.      

Compensation for decreased expression of B7 molecules on Leishmania infantum-infected canine macrophages results in restoration of parasite-specific T-cell proliferation and gamma interferon production

Infection of humans and dogs by Leishmania infantum may result in visceral leishmaniasis, which is characterized by impaired T-cell-mediated immune responses to parasite antigens. Dogs are natural hosts of Leishmania parasites and play an important role in the transmission of the parasites to humans. In an effort to characterize the immune response in dogs infected with this intracellular pathogen, we examined how infection with L. infantum affects canine macrophages and the consequences for T-cell activation in vitro. We showed that the proliferation of T-cell lines to cognate antigen decreases to background levels when infected autologous monocyte-derived macrophages are used as antigen-presenting cells (APC). The observed reduction of antigen-specific T-cell proliferation was shown to be dependent on the parasite load and to require cell-to-cell interaction of T cells with the infected APC. In addition, we observed a decreased expression of costimulatory B7 molecules on infected monocyte-derived macrophages. The expression of other surface molecules involved in T-cell activation, such as major histocompatibility complex class I and class II, on these cells did not change upon infection, whereas the expression of intracellular adhesion molecule 1 was marginally increased. Compensation for the decreased expression of B7 molecules by the addition of B7-transfected cells resulted in the restoration of cell proliferation and gamma interferon (IFN-gamma) production by a Leishmania-specific T-cell line. These results showed that for the activation of parasite-specific canine T cells producing IFN-gamma, which are most likely involved in protective immunity, sufficient expression of B7 molecules on infected macrophages is required. Provision of costimulatory molecules may be an approach for immunotherapy of leishmaniaisis as well as for vaccine development.     

Brain proton magnetic resonance spectroscopy (1H-MRS) in Alzheimer's disease: changes after treatment with xanomeline, an M1 selective cholinergic agonist

OBJECTIVE: Higher than normal cellular levels of the phospholipid catabolic intermediate glycerophosphocholine have been found in postmortem brain tissue of persons with Alzheimer's disease. Proton magnetic resonance spectroscopy (1H-MRS) can detect a choline resonance that is largely due to glycerophosphocholine. The authors tested the hypothesis that treatment with xanomeline, an M1 selective muscarinic cholinergic agonist, would be associated with a decrease in the 1H-MRS choline resonance. METHOD: Patients with mild to moderate Alzheimer's disease received placebo or xanomeline for 6 months. 1H-MRS spectra were collected at baseline and after treatment discontinuation for 12 patients, two taking placebo and 10 taking xanomeline at a dose of 25 mg t.i.d. (N = 4), 50 mg t.i.d. (N = 3), or 75 mg t.i.d. (N = 3). RESULTS: For the combined group of patients taking xanomeline, there was a significant decrease in the choline/creatine ratio from baseline to endpoint. CONCLUSIONS: Treatment of Alzheimer's disease with a cholinergic agonist is associated with a decrease in the MRS choline resonance. Xanomeline may reduce breakdown of cholinergic neuron membranes by reducing the cellular requirement for free choline for acetylcholine synthesis.