Thermal stability of processed PVC/bamboo blends: effect of compounding procedures

Polyvinyl chloride (PVC) was mixed with bamboo (Bambusa vulgaris) particle and additives by using PVC composite manufacturing system including initial dry blending with hot-cool mixing, followed by granulation via counter-rotating extrusion, and then consolidation by compression moulding to produce compression moulded board (CMB). The effects of different bamboo particle size (75 µm and 1 mm), bamboo particle loading (25 and 50% loading ratio), and differing processing lubricants content level (compositions 1 and 2) on the thermal stability of the composites were determined. Results show no significant trends in glass transition temperature (T_g) between dry blends, granules, and CMB, and between B. vulgaris particle loading at the respective processing steps. For samples with higher lubricant contents, the PVC T_g was observed to decrease up to 5?°C, possibly due to the reduced melt viscosity. The thermal decomposition temperature at 5% mass loss (T_?5%) appeared to decrease from dry blend to CMB due to sample degradation on further processing at higher temperatures. The use of 50% B. vulgaris particle loading also reduced the T_?5% values, assignable to bamboo particle degradation caused by the high processing temperatures. For oxidative induction time (OIT) testing, only granules and CMB from pure PVC composites system showed measurable oxidative times compared with OIT profiles of PVC/B. vulgaris composites system, suggestive of comparatively stabilized thermoplastic composites. This revealed that processing with bamboo particles does not contribute to degradation of PVC composites.     

Accounting for randomness in measurement and sampling in studying cancer cell population dynamics

Knowing the expected temporal evolution of the proportion of different cell types in sample tissues gives an indication about the progression of the disease and its possible response to drugs. Such systems have been modelled using Markov processes. We here consider an experimentally realistic scenario in which transition probabilities are estimated from noisy cell population size measurements. Using aggregated data of FACS measurements, we develop MMSE and ML estimators and formulate two problems to find the minimum number of required samples and measurements to guarantee the accuracy of predicted population sizes. Our numerical results show that the convergence mechanism of transition probabilities and steady states differ widely from the real values if one uses the standard deterministic approach for noisy measurements. This provides support for our argument that for the analysis of FACS data one should consider the observed state as a random variable. The second problem we address is about the consequences of estimating the probability of a cell being in a particular state from measurements of small population of cells. We show how the uncertainty arising from small sample sizes can be captured by a distribution for the state probability.Inspec keywords: cancer, tumours, cellular biophysics, biomedical measurement, Gaussian distribution, maximum likelihood estimation, mean square error methods, hidden Markov models, fluorescence, random processes, convergence of numerical methodsOther keywords: cancer cell population dynamics, malignant tumours, tissue samples, normal tissue cells, disease, drugs, Markov process, cell population size measurement, hidden Markov model, noisy measurement, state transition probability, fluorescence‐activated cell sorting measurement, minimum mean square error estimator, maximum likelihood estimator, transition probability matrix, noise distributions, Gaussian distributions, MMSE, convergence mechanism, standard deterministic approach, stochastic phenomena, random variable     

Structural and Electrical Properties of Ta ax La(1−a)x O y Thin Films

Effect of annealing temperature on the characteristics of sol–gel-driven Ta _ax La_(1?a)x O _y thin film spin-coated on Si substrate as a high-k gate dielectric was studied. Ta _ax La_(1?a)x O _y thin films with different amounts of a were prepared (as-prepared samples). X-ray diffraction measurements of the as-prepared samples indicated that Ta_0.3x La_0.7x O_y film had an amorphous structure. Therefore, Ta_0.3x La_0.7x O _y film was chosen to continue the present studies. The morphology of Ta_0.3x La_0.7x O _y films was studied using scanning electron microscopy and atomic force microscopy techniques. The obtained results showed that the size of grain boundaries on Ta_0.3x La_0.7x O _y film surfaces was increased with increasing annealing temperature. Electrical and optical characterizations of the as-prepared and annealed films were investigated as a function of annealing temperature using capacitance–voltage (C–V) and current density–voltage (J–V) measurements and the Tauc method. The obtained results demonstrated that Ta_0.3x La_0.7x O _y films had high dielectric constant (≈27), wide band gap (≈4.5 eV), and low leakage current density (≈10^?6 A/cm² at 1 V).     

Investigation into the fouling mechanism in a RO hollow fine-fibre module

As a service to readers who understand German, French or Spanish better than English, the abstract for the research article in this issue follow in these languages.     

Fouling of microfiltration membranes by biopolymers

Suppression of fouling due to biopolymers of relevance to the brewing industry has been investigated. The effects of three model biopolymers: casein (protein), catechin (polyphenol), and dextran (polysaccharide) on fouling of asymmetric 0.65 μm polyethersulfone membranes during direct-flow filtration have been studied. While dextran is successful in disrupting interactions between casein and catechin, the associated reduction in aggregate size does not always result in reduced fouling. Solution conditions such as pH and ionic strength modulate the tendency of the aggregates to adsorb onto the membrane surface. Thus, optimizing solution conditions to suppress adsorption of aggregates is essential for increasing the membrane filtration capacity.     

Determination of Lead,Cadmium, Copper,and Zinc Content in Commercial Iranian Vinegars Using Stripping Chronopotentiometry

The rapid stripping chronopotentiometry (SCP) method was used to determine copper, lead, cadmium, and zinc in different kinds of vinegars (date, white grape, red grape, and apple) produced in Iran. The results of SCP were compared with graphite furnace atomic absorption spectrometry (GFAAS) as a reference method. There were no significant differences (p > 0.5) between the two methods. The range of concentration (ng/ml) of the analytes for heavy metals in different kinds of vinegars was as follows: copper (12.79–1,129), lead (3.32–253), cadmium (non-detectable concentration to 78), and zinc (26.12–3,725). The results demonstrated that it is possible to accurately determine the copper, lead, cadmium, and zinc content by direct analysis of vinegar samples using SCP method. The metal concentrations in all samples were lower than the maximum allowable limits legislated by the Institute of Standards and Industrial Research of Iran.     

Spectrum sensing and power/rate control in CDMA cognitive radio networks

In this paper, a two‐phase algorithm for the spectrum sensing and power/rate control of a secondary user (S‐user) or cognitive radio is proposed. In the first phase, the primary base station (P‐BS), which is conscious of both the number and the data rate of primary active users (P‐user), broadcasts theitusage capacity percentage (UCP) of its cell. Since knowing only the UCP is not enough to guarantee that the total load (of P‐users and S‐users) is less than a maximum permissible load, the S‐user must measure the total interference received from both the P‐users and other S‐users. In this direction, using both the UCP and measurement of the interference received from the P‐users and the S‐users by the S‐user or secondary base station (S‐BS), we mathematically derive an equation for issuing data transmission permission, which if it is held then the second phase of the algorithm: the transmit power/rate control starts. In this phase, the S‐user and the S‐BS look for feasible values for the transmit power level and transmission rate. If there are feasible values, it starts its transmission at these feasible transmit power and rate. Since both the location of the S‐user and the channel condition vary in time, the whole algorithm is iterated periodically with a period faster than the coherence time of the channel. Furthermore, we consider the down link of the above system with cooperation among neighboring S‐users to overcome fading channels and we investigate the amount of improvement in the reliability of the issuing data transmission permission. As well, we consider the uplink of the system with multiple antennas in the S‐BS to investigate the improvement in the same parameter over spatially correlated and independent fading channels. Theoretical analysis is validated using computer simulations. Both theoretical analysis and computer simulations show that the proposed cooperative spectrum sensing algorithm performs properly at SNR = ?5dB in flat Nakagami‐m fading channels with m = 1 even in correlated fading channels. We also address the improvement of the reliability of the issuing data transmission permission in the uplink in case of using multiple antennas only in the S‐BS. Copyright © 2011 John Wiley & Sons, Ltd.     

Drilling cost optimization in a hydrocarbon field by combination of comparative and mathematical methods

In drilling operation,a large saving in time and money would be achieved by reducing the drilling time,since some of the costs are time-dependent.Drilling time could be minimized by raising the penetration rate.In the comparative optimization method,by using the records of the first drilled wells and comparing the criteria like penetration rate,cost per foot and specific energy,the drilling parameters of the next wells being drilled can be optimized in each depth interval.In the mathematical optimization technique,some numerical equations to model the penetration rate,bit wear rate and hydraulics would be used to minimize the drilling cost and time as much as possible and improve the results of the primary comparative optimization.In this research,as a case study the Iranian Khangiran gas field has been evaluated to optimize the drilling costs.A combination of the mentioned optimization techniques resulted in an optimal well which reduced the drilling time and cost considerably in comparison with the wells already drilled.     

Bisphenol A (BPA) Leading to Obesity and Cardiovascular Complications: A Compilation of Current In Vivo Study

BPA is one of the most common endocrine disruptors that is widely being manufactured daily nationwide. Although scientific evidence supports claims of negative effects of BPA on humans, there is also evidence suggesting that a low level of BPA is safe. However, numerous in vivo trials contraindicate with this claim and there is a high possibility of BPA exposure could lead to obesity. It has been speculated that this does not stop with the exposed subjects only, but may also cause transgenerational effects. Direct disruption of endocrine regulation, neuroimmune and signaling pathways, as well as gut microbiata, has been identified to be interrupted by BPA exposure, leading to overweight or obesity. In these instances, cardiovascular complications are one of the primary notable clinical signs. In regard to this claim, this review paper discusses the role of BPA on obesity in the perspective of endocrine disruptions and possible cardiovascular complications that may arise due to BPA. Thus, the aim of this review is to outline the changes in gut microbiota and neuroimmune or signaling mechanisms involved in obesity in relation to BPA. To identify potentially relevant articles, a depth search was done on the databases Nature, PubMed, Wiley Online Library, and Medline & Ovid from the past 5 years. According to Boolean operator guideline, selected keywords such as (1) BPA OR environmental chemical AND fat OR LDL OR obese AND transgenerational effects or phenocopy (2) Endocrine disruptors OR chemical AND lipodystrophy AND phenocopy (3) Lipid profile OR weight changes AND cardiovascular effect (4) BPA AND neuroimmune OR gene signaling, were used as search terms. Upon screening, 11 articles were finalized to be further reviewed and data extraction tables containing information on (1) the type of animal model (2) duration and dosage of BPA exposure (3) changes in the lipid profile or weight (4) genes, signaling mechanism, or any neuroimmune signal involved, and (5) transgenerational effects were created. In toto, the study indicates there are high chances of BPA exposure affecting lipid profile and gene associated with lipolysis, leading to obesity. Therefore, this scoping review recapitulates the possible effects of BPA that may lead to obesity with the evidence of current in vivo trials. The biomarkers, safety concerns, recommended dosage, and the impact of COVID-19 on BPA are also briefly described.