Biodegradable hollow microfibres to produce bioactive scaffolds

Biodegradable hollow microfibres containing particles loaded with specific active agents can be potentially employed to produce a special kind of substrate for tissue engineering, able to function as a scaffold and at the same time to act as a drug‐releasing system. Biodegradable hollow microfibres based on poly(lactic acid) were produced by a dry–wet spinning procedure. Drug‐loaded microparticles were prepared by a simple oil‐in‐water emulsion and entrapped inside the fibres. The morphology of both fibres and particles was investigated by scanning electron microscopy. The mechanical and thermal properties of the fibres were investigated by tensile tests and differential scanning calorimetry. In vitro tests were performed to evaluate the release of the drug from the fibres loaded with the particles Copyright © 2004 Society of Chemical Industry     

THE EFFECT OF CATHODIC PROTECTION POTENTIAL ON CORROSION FATIGUE CRACK GROWTH RATE OF AN OFFSHORE STRUCTURAL STEEL

Abstract— Duplicate tests have been performed to determine the effect of cathodic protection potential on corrosion fatigue crack growth rate of a modern offshore structural steel, produced by thermo-mechanically controlled processes. The experiments were carried out using compact tension specimens exposed to artificial seawater at 10°C and subjected to constant amplitude loading at 0.35 Hz. Reproducible results showed that the merits of cathodic protection potentials are strongly dependent on stress intensity ratio R and stress intensity range Δ K . It appears that a specific value of cathodic potential may not give comprehensive protection against corrosion fatigue within the spectrum of variable amplitude loading experienced in service. Fractography showed the initiation of secondary cracks on the fracture surface to be associated with the dissolution of calcium sulphide inclusions, regardless of imposed cathodic potential.     

Supplementation with SCFAs Re-Establishes Microbiota Composition and Attenuates Hyperalgesia and Pain in a Mouse Model of NTG-Induced Migraine

Migraine is a common brain-disorder that affects 15% of the population. Converging evidence shows that migraine is associated with gastrointestinal disorders. However, the mechanisms underlying the interaction between the gut and brain in patients with migraine are not clear. In this study, we evaluated the role of the short-chain fatty acids (SCFAs) as sodium propionate (SP) and sodium butyrate (SB) on microbiota profile and intestinal permeability in a mouse model of migraine induced by nitroglycerine (NTG). The mice were orally administered SB and SP at the dose of 10, 30 and 100 mg/kg, 5 min after NTG intraperitoneal injections. Behavioral tests were used to evaluate migraine-like pain. Histological and molecular analyses were performed on the intestine. The composition of the intestinal microbiota was extracted from frozen fecal samples and sequenced with an Illumina MiSeq System. Our results demonstrated that the SP and SB treatments attenuated hyperalgesia and pain following NTG injection. Moreover, SP and SB reduced histological damage in the intestine and restored intestinal permeability and the intestinal microbiota profile. These results provide corroborating evidence that SB and SP exert a protective effect on central sensitization induced by NTG through a modulation of intestinal microbiota, suggesting the potential application of SCFAs as novel supportive therapies for intestinal disfunction associated with migraine.     

Optimizing the order picking of a scholar and office supplies warehouse

The warehouse operation planning in the scholar and office supplies industry encompasses the activities of receiving, storing, order picking, and shipping products. The order picking operation is a laborious and capital intensive procedure. Despite the extensive literature to solve practical problems of warehouse routing as a step of the order picking process, the application of general approaches to deal with the routing of the warehouse pickers is not straightforward given the specific conditions and configurations and the singular design and operational policies commonly found in practice. In this paper, we present an optimization approach to the stacker routing problem found in the order picking of a Brazilian scholar and office supplies company. The approach is based on a routing algorithm that solves different integer linear problems to define the optimal routes of the stacker inside the facility. The solutions of several numerical experiments show the potential and effectiveness of the approach, for instance, that only one fifth of the routes actually performed by the company are optimal and that the algorithm application to a real set of batches reduced by more than one fourth the total distance monthly traveled by the stacker.     

Faecal carriage of Verocytotoxin-producing Escherichia coli O157 and carcass contamination in cattle at slaughter in northern Italy.

A study on the prevalence of the faecal carriage of Verocytotoxin (VT)-producing Escherichia coli (VTEC) O157 and on the rate of carcass contamination was carried out on feedlot cattle and dairy cows at slaughter in northern Italy. Between April 1998 and January 1999, 12 sampling visits were performed on different days in seven different slaughterhouses. At each visit, 5-12 animals consecutively slaughtered were selected. From each animal, faeces were collected from the rectum immediately after slaughter and surface swabs were taken from the leg region and the diaphragmatic insertion of the carcass. All samples were examined for the presence of VTEC O157 using an immunomagnetic separation technique. A total of 100 animals coming from 60 different farms were examined. In total, VTEC O157 was isolated from the intestinal content of 17, and from the carcasses of 12 of the 100 animals examined. In particular, VTEC O157 was recovered from six (35.3%) out of the 17 carcasses from which the organism had previously been isolated from rectal content and from six (7.3%) of the 82 carcasses of the stool-negative cattle. In seven carcasses, VTEC O157 was isolated from the leg area, in two carcasses from the diaphragmatic area, and in three carcasses from both areas. Major differences in the prevalence of VTEC O157 were observed in the different groups of cattle sampled. In 7 of the 12 sampling visits, all the specimens examined were negative, while 16 of the 17 positive stool samples and 11 of the 12 positive carcass swabs were collected during three of the visits, performed in June in three different abattoirs. In these three visits, the ratios between the percentage of animals carrying VTEC O157 in the stools and the percentage of contaminated carcasses were 0.33, 0.57, and 1.66, respectively; thus, confirming that slaughter practices can largely influence the rate of carcass contamination. Phage typing and PFGE analysis of VTEC O157 isolated from samples collected at the same visit suggested that both auto- and cross-contamination occurred.     

Interdiffusion in the CuAu thin film system at 25°C to 250°C

Interdiffusion in the Cu-Au system has been studied in the temperature range 25–250°C using conductivity measurements and Auger in-depth composition profiles. Samples were prepared by three different methods: (1) Au was evaporated over evaporated Cu, (2) Au was electroplated over electroplated Cu and (3) Au was electroplated over wrought (bulk) Cu.The conductivity data for both the evaporated and the plated samples could be represented by $\text{ΔG}\text{G}\text{= 0.030{1?exp(?10}{}^5\text{t}\text{k}\text{)} ? (}\text{t}\text{k}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ where G is the conductance, t the time and k is an acceleration factor which is a function of temperature and thickness. Interdiffusion coefficients D? were obtained from the conductivity data by using the measured acceleration factors. These data can also be used to predict sheet conductance changes for reasonable thicknesses of Cu and Au films. Auger composition profiles were obtained by analysis beginning at the original Au-to-air interface and proceeding through the Au film into the Cu. Three distinct regions were found: (1) Cu oxide growth at the original Au surface, (2) a plateau region of a few atomic per cent Cu in the Au film and (3) a zone around the original Au-Cu interface where the Cu concentration rises to 100%. Interdiffusion coefficients were obtained from the Auger profiles based on the concentration gradient at the Au-Cu interface (region (3)).Interdiffusion coefficients obtained from $\text{ΔG}\text{G}$ and from the Auger profiles agreed within a factor of 10 for all three methods of specimen preparation. Over the range 50–250°C the interdiffusion coefficient could be represented by $\text{D}\text{= 2.9 × 10}{}^{\mathrm{?3}}\text{exp(?1.21}\text{eV}\text{kT}\text{) cm}{}^2\text{s}{}^{\mathrm{?1}}$, giving 1.3 × 10^-19 cm² s^-1 at 100°C and 6.2 × 10^-15 cm² s^-1 at 250°C. These values fall within the range of extrapolations of previously published data obtained at higher temperatures.Auger profiles from a Cu ribbon which had been Au plated and stored for 18 years at room temperature prior to analysis were used to obtain an upper limit of 2 × 10^-20 cm² s^-1 for the interdiffusion coefficient at 25°C. Subsequent measurements of D? on this sample at 150–250°C were in agreement with values obtained for the other two types of CuAu specimens. This agreement leads to the conclusion that the room temperature interdiffusion coefficient in the other two types of samples is also less than 2 × 10^-20 cm² s^-1.     

A discrete-time paradigm to evaluate skew performance in amultimedia ATM multiplexer

One of the most important quality-of-service parameters in a multimedia environment is skew, defined as the difference between the delays suffered by the monomedia flows belonging to the same multimedia stream. An analytical paradigm is proposed to evaluate the skew affecting a multimedia traffic stream in an asynchronous transfer mode multiplexer. For this purpose, the emission process of each multimedia source loading the multiplexer is defined as the superposition of heterogeneous correlated emission processes, each of which models one monomedia source as a switched batch Bernoulli process (SBBP). In order to model the intermedia relationships, the transition probabilities in the Markov chain underlying each SBBP are functions of the state of the other monomedia sources. The model is applied to a case study and the dependence of skew performance on some of the source characteristics, such as intermedia correlation, and some of the environment characteristics, such as buffer size, output capacity, and buffer utilization is analyzed and discussed     

Crime hotspot mapping using the crime related factors—a spatial data mining approach

The technique of Hotspot Mapping is widely used in analysing the spatial characteristics of crimes. The spatial distribution of crime is considered to be related with a variety of socio-economic and crime opportunity factors. But existing methods usually focus on the target crime density as input without utilizing these related factors. In this study, we introduce a new crime hotspot mapping tool—Hotspot Optimization Tool (HOT). HOT is an application of spatial data miming to the field of hotspot mapping. The key component of HOT is the Geospatial Discriminative Patterns (GDPatterns) concept, which can capture the differences between two classes in a spatial dataset. Experiments are done using a real world dataset from a northeastern city in the United States and the pros and cons of utilizing related factors in hotspot mapping are discussed. Comparison studies with the Hot Spot Analysis tool implemented by Esri ArcMap 10.1 validate that HOT is capable of accurately mapping crime hotspots.