Microporous anisotropic phase inversion membranes from bisphenol A polycarbonate: Effect of additives to the polymer solution

Phase inversion is a very flexible technique to obtain membranes with a large sort of morphologies. Membrane properties can vary greatly depending on the kind of polymer system used. Bisphenol A polycarbonate (PC) could be used as a phase inversion membrane base polymer, and presents very good properties. Nevertheless, very little information on membrane preparation using PC and the phase inversion process can be found in the literature. In this work flat‐sheet microporous membranes were obtained by the phase inversion process using the immersion precipitation technique. A new polymer system was studied, consisting of polycarbonate, N‐methyl‐2‐pyrrolidone as solvent, water as the nonsolvent, and an additive. The influence of some parameters on membrane morphology, such as polymer solution composition, exposition time before immersion into the precipitation bath, and the kind of additive was investigated. Precipitation was followed using light transmission experiments and membrane morphology was observed through Scanning Electron Microscopy (SEM). The viscosity and cloud points of all polymer solutions were also determined. The results were related to the studied synthesis parameters, using the basic principles of membrane formation by the phase inversion technique, looking forward to establishing criteria to control the morphology of flat‐sheet membranes using polycarbonate as the base polymer. The results showed that both additives were able to increase pore interconnectivity and even suppress macrovoid formation. The decrease in the miscibility region of the polymer system and increase in mass transfer resistance are found to be the determining factors during polymer solution precipitation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3085–3096, 2002     

Two new aluminophosphates, IST-1 and IST-2: First examples of a dual templating role of water and methylamine in generating microporous structures

This study is aimed at exploring the ability of very small sized N-bearing molecules to generate and stabilize microporous aluminophosphates. Two new AlPO₄-n materials, called IST-1 and IST-2, have been obtained in aqueous media using, as main template, methylamine (MA), directly added, or generated in situ from methylformamide (MF) degradation. While IST-1 topology proved to be novel, IST-2 appears structurally related to AlPO₄-53(A). The obtained materials were characterized by powder XRD, TG/DSC, SEM and solid-state NMR. Tetraalkylammonium (TEA) cations were used as potential co-templates but only MA and water were found incorporated in the pore volumes of both structures, which argues for their true templating role. In IST-1, ¹³C solid-state NMR studies showed that half of MA species, presumably protonated, is H-bonded to framework oxygens while the other half surprisingly bonds directly to framework Al atoms. ¹³C NMR showed that only protonated MA occurs in IST-2 channels. TEA⁺ cations definitely do not play any specific template role. They indirectly favor the crystallization of IST-1 or IST-2 devoid from other crystalline or amorphous side phases, by interacting with part of the Al and P in solution and forming soluble [AlPO₄(OH)]–[TEA,HMA] complexes, substantially modifying the compositions of gels precursors to each phase during nucleation and/or growth steps. While both IST-1 and IST-2 crystallize from gels of similar initial compositions, it was demonstrated that the new MA/T ratio (T = Al or P) obtained after in situ complexation was the key parameter that specifically governs the crystallization of each phase.     

A Closed-Loop Automatic Data-Mining Approach for Preventive Network Monitoring

As telecommunication networks grow in size and complexity, monitoring systems need to scale up accordingly. Alarm data generated in a large network are often highly correlated. These correlations can be explored to simplify the process of network fault management, by reducing the number of alarms presented to the network-monitoring operator. This makes it easier to react to network failures. But in some scenarios, it is highly desired to prevent the occurrence of these failures by predicting the occurrence of alarms before hand. This work investigates the usage of data mining methods to generate knowledge from historical alarm data, and using such knowledge to train a machine learning system, in order to predict the occurrence of the most relevant alarms in the network. The learning system was designed to be retrained periodically in order to keep an updated knowledge base.     

Mass spectrometric immunoassay and MRM as targeted MS-based quantitative approaches in biomarker development: Potential applications to cardiovascular disease and diabetes

Type 2 diabetes mellitus (T2DM) is an important risk factor for cardiovascular disease (CVD)—the leading cause of death in the United States. Yet not all subjects with T2DM are at equal risk for CVD complications; the challenge lies in identifying those at greatest risk. Therapies directed toward treating conventional risk factors have failed to significantly reduce this residual risk in T2DM patients. Thus newer targets and markers are needed for the development and testing of novel therapies. Herein we review two complementary MS-based approaches—mass spectrometric immunoassay (MSIA) and MS/MS as MRM—for the analysis of plasma proteins and PTMs of relevance to T2DM and CVD. Together, these complementary approaches allow for high-throughput monitoring of many PTMs and the absolute quantification of proteins near the low picomolar range. In this review article, we discuss the clinical relevance of the high density lipoprotein (HDL) proteome and Apolipoprotein A-I PTMs to T2DM and CVD as well as provide illustrative MSIA and MRM data on HDL proteins from T2DM patients to provide examples of how these MS approaches can be applied to gain new insight regarding cardiovascular risk factors. Also discussed are the reproducibility, interpretation, and limitations of each technique with an emphasis on their capacities to facilitate the translation of new biomarkers into clinical practice.     

Prosthetic valve endocarditis: superiority of surgical valve replacement versus medical therapy only

The objective of our study was to assess the long-term outcome of patients with prosthetic valve endocarditis. We used a multicenter, prospective, observational study design. Six university teaching hospitals with high volume cardiothoracic surgery participated. Seventy-four patients with prosthetic valve endocarditis as defined by explicit, objective criteria were selected for participation. All patients were followed up prospectively for 1 year. Thirty-one percent and 69% had development of endocarditis within 60 days of valve insertion ("early") and after 60 days ("late"), respectively. The most common causes were Staphylococcus epidermidis (40%), Staphylococcus aureus (20%), streptococcal species (18%), and aerobic gram-negative bacilli (11%). Physical signs of endocarditis (new or changing murmur, stigmata, emboli) were seen in 58%. At 6 months and 12 months, mortality was 46% and 47%, respectively. Surgical replacement of the infected valve led to significantly lower mortality (23%) as compared with medical therapy alone (56%), as assessed by both univariate and multivariate analyses (p < 0.05). Improved outcome was seen for the surgical group even when controlling for severity of illness at time of diagnosis. From these findings we conclude that accurate assessment of outcome in prosthetic valve endocarditis requires long-term follow-up of at least 6 months following diagnosis. Surgical therapy warrants greater scrutiny; evaluation in controlled clinical trials is appropriate.     

Use of 3D printing for biofuel production: efficient catalyst for sustainable biodiesel production from wastes

This work deals with the sustainable biodiesel production from low-cost renewable feedstock (waste and non-edible oils) using a heterogeneous catalyst constituted by potassium loaded on an amorphous aluminum silicate naturally occurring as volcanic material (pumice). The main challenge to biodiesel production from low-quality oils (used oils and greases) is the high percentage of free fatty acids (FFAs) and water in the feedstock that causes undesirable side reactions. The catalytic materials studied were tested in the transesterification reaction when using low-quality oils containing a high proportion of free fatty acids (FFAs) and water. Results indicated that the amount of acid and basic sites on the catalytic surface increases upon increasing potassium loading in the catalyst, displaying better performance for biodiesel production. Indeed, the modification of the aluminum silicate substrate upon potassium incorporation results in a catalytic material containing both acidic and basic sites, which are responsible for both triglycerides transesterification and FFA esterification reactions. The studied catalyst not only showed good performance in the biodiesel production reaction but also good tolerance to FFA and water contained in the feedstock for biodiesel production. The catalytic material was microstructured by 3D printing in order to design a catalytic stirring system with high mechanical strength, efficient and reusable. The use of 3D printing in biofuel production is a novelty that brings good solutions for catalyst production.     

Laparoscopic versus open appendectomy

BACKGROUND: Clinical manifestations and course of sickle-cell anemia are variable. Knowledge about the factors, possibly geographic, that influence prognosis are still scanty. POPULATION AND METHODS: Data of hospitalization and management of children with sickle-cell disease were studied during two years (1992-1993) in the Pediatric Unit of Libreville Hospital. They concerned 205 admissions of 171 children and 131 outpatients. RESULTS: The main causes of hospitalization were: acute anemia (36 cases before the age of 5 years); painful crisis whose frequency increased with age (23% before 5 years, 35% between 5 and 10, 42% after 10 years); infections, essentially pulmonary occurring early, and bone infections at any age. Eight children died (because a complication of their disease). Among the 131 outpatients, half were detected because pyrexia, anemia and/or more often "hand-foot syndrome". More than 60% had hepatomegaly, one third still had splenomegaly after five years of age and more than one third was icteric. More than half children older than ten years had growth disorders. Mean hemoglobin level was 7 g/dL. 21 of the 83 tested children for HBsAg were positive and only one out of 79 was positive for HIV. CONCLUSIONS: Clinical manifestations and course of sickle-cell anemia in our patients are similar to those reported in Congolese children. Genetic and environmental factors may be responsible for differences with children from other, in particular French, cohorts.     

Scientific productivity paradox: The case of China's S&T system

Summary In 1985 China began the reform of its Science & Technology (S&T) sector inherited from the planned economy. To disclose the impact of the drawn-out reform on the efficiency of the whole sector, we measure the scientific productivity of China's S&T institutes. The analysis is based on R&D input and output data at the country aggregate and provincial level. We utilize Polynomial Distributed Lag model to uncover the structure of the lag between R&D input and output. The findings reveal that the growth rate of scientific productivity of China's S&T institutes has been negative since the 1990s.