Parameters affecting the synthesis of geranyl butyrate by esterase 30,000 from Mucor miehei

The factors affecting the synthesis of geranyl butyrate by esterase 30,000 of Mucor miehei were studied in a solvent-free system. The effects of substrate molar ratio, temperature, agitation speed, and initial addition of water were investigated. The equimolar ratio was most interesting for ester production in batch. There were no diffusion limitations, and the reaction could be realized at low agitation. The catalytic activity of the enzyme was irreversibly deactivated at 60°C, and the initial addition of water decreased the rate of conversion after 75 h of reaction. The enzyme activity increased with increased linear chainlength of the acid and was also affected by the alcohol structure. Esterase 30,000 gave the highest conversion of butyric acid with hexanol and terpenic alcohols (citronellol, nerol) and the lowest with the secondary alcohol (2-hexanol). Finally, five other industrial enzymatic preparations were investigated for their ability to synthesize geranyl butyrate and to hydrolyze olive oil. We observed, for the lipase from Rhizopus javanicua, that there is no relationship between hydrolytic and synthetic activities; this example shows that the hydrolytic lipase activity data cannot predict the capability of lipases in esterification reactions.     

Pollution in the water supply wells of Khartoum, Sudan

 The supply of water to Khartoum, Sudan, is from wells tapping aquifers in the Nubian Sandstone Formation. The boreholes are located in residential areas where sewage disposal is by means of a siphon septic tank system draining into the water table in the upper alluvial deposits. The aquifers are leaky to unconfined in nature and as the lower groundwater moves from the Nile towards the residential areas, it is susceptible to pollution from the septic tanks. Evidence that such pollution is occurring was found in three production wells where the presence of E. coli bacteria was identified. Received: 9 July 1998 · Accepted: 20 May 1999     

Cellulose membranes grafted with vinyl monomers in homogeneous system

The homogeneous grafting of a hydrophilic monomer onto cellulose derivatives was carried out in an aqueous system at 30, 50, 70, and 90°C during reaction periods of 30–180 min. The graft polymer was isolated by ethanol from the reaction mixture, dried, and weighed. The grafted polymer was characterized by the IR method, as well as the microscopic sample morphology detected by scanning electron microscopy. The water absorption capacities and grafting values of the grafted cellulose derivatives were also determined. The maximum grafting yield was obtained at 30°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2629–2638, 2002     

Characterization of hydrogen charging of 2205 duplex stainless steel and its correlation with hydrogen‐induced cracking

The effect of various experimental conditions (i.e., hydrogen charging current density, charging time, solution concentration, and temperature) on the embrittlement and cracking susceptibility of 2205 duplex stainless steel was studied by electrochemical hydrogen charging and slow strain rate tests. The results showed that the choice of the experimental conditions had obvious effect on the hydrogen concentration in the specimens. A relationship between the embrittlement and hydrogen charging conditions was established by the investigation of the fracture morphology. Under the free‐charging condition, the fracture surfaces were characteristic of dimples, while on the condition of the dynamic hydrogen charging, the hydrogen‐induced fracture showed the appearance of cleavage. Further examination of fracture cracks confirmed that the ferrite phase acts as a preferential path for crack propagation.     

FENTON AND FENTON-LIKE AOPs FOR ALUM SLUDGE CONDITIONING: EFFECTIVENESS COMPARISON WITH DIFFERENT Fe2+ AND Fe3+ SALTS

Currently, organic polymers are adopted in alum sludge (aluminum-coagulated drinking water treatment sludge) conditioning. However, there are important concerns regarding the use of these polymers because of the unknown and long-term effects of the potential release of excess polymer to the surrounding environment when the sludge is landfilled. Therefore, as an initial action, this study aimed at investigating alternative chemical conditioning methods and focused mainly on exploiting Fenton (Fe²⁺/H₂O₂) and Fenton-like (Fe³⁺/H₂O₂) reagents as the conditioner. Experiments have been conducted to test the effectiveness of Fenton's reagent (containing the ferrous salts of chloride, sulfate, or oxalate), Fenton-like reagent (containing ferric salts of chloride and sulfate), and the coagulation method using FeCl₃ for alum sludge conditioning at constant hydrogen peroxide and iron salt concentrations of 125 and 20 mg/g DS (dry solids), respectively. The effectiveness on dewaterability of the alum sludge demonstrated that the maximum reduction (%) of SRF (specific resistance to filtration) and CST (capillary suction time) of 74% and 47%, respectively, can be obtained when Fenton's reagent was adopted for sludge conditioning. Such reduction of 64% for SRF and 38% for CST can be achieved when Fenton-like reagents were applied.     

Field programmable analog arrays for implementation of generalized nth‐order operational transconductance amplifier‐C elliptic filters

This study presents a new architecture for a field programmable analog array (FPAA) for use in low‐frequency applications, and a generalized circuit realization method for the implementation of nth‐order elliptic filters. The proposed designs of both the FPAA and elliptic filters are based on the operational transconductance amplifier (OTA) used in implementing OTA‐C filters for biopotential signal processing. The proposed FPAA architecture has a flexible, expandable structure with direct connections between configurable analog blocks (CABs) that eliminates the use of switches. The generalized elliptic filter circuit realization provides a simplified, direct synthetic method for an OTA‐C symmetric balanced structure for even/odd‐nth‐order low‐pass filters (LPFs) and notch filters with minimum number of components, using grounded capacitors. The filters are mapped on the FPAA, and both architectures are validated with simulations in LTspice using 90‐nm complementary metal‐oxide semiconductor (CMOS) technology. Both proposed FPAA and filters generalized synthetic method achieve simple, flexible, low‐power designs for implementation of biopotential signal processing systems.     

A computational intelligence approach for a better diagnosis of diabetic patients

Knowledge discovery refers to identifying hidden and valid patterns in data and it can be used to build knowledge inference systems. Decision tree is one such successful technique for supervised learning and extracting knowledge or rules. This paper aims at developing a decision tree model to predict the occurrence of diabetes disease. Traditional decision tree algorithms have a problem with crisp boundaries. Much better decision rules can be identified from these clinical data sets with the use of the fuzzy decision boundaries. The key step in the construction of a decision tree is the identification of split points and in this work best split points are identified using the Gini index. Authors propose a method to minimize the calculation of Gini indices by identifying false split points and used the Gaussian fuzzy function because the clinical data sets are not crisp. As the efficiency of the decision tree depends on many factors such as number of nodes and the length of the tree, pruning of decision tree plays a key role. The modified Gini index-Gaussian fuzzy decision tree algorithm is proposed and is tested with Pima Indian Diabetes (PID) clinical data set for accuracy. This algorithm outperforms other decision tree algorithms.     

A Deep-CNN Crowd Counting Model for Enforcing Social Distancing during COVID19 Pandemic: Application to Saudi Arabia’s Public Places

With the emergence of the COVID19 virus in late 2019 and the declaration that the virus is a worldwide pandemic, health organizations and governments have begun to implement severe health precautions to reduce the spread of the virus and preserve human lives. The enforcement of social distancing at work environments and public areas is one of these obligatory precautions. Crowd management is one of the effective measures for social distancing. By reducing the social contacts of individuals, the spread of the disease will be immensely reduced. In this paper, a model for crowd counting in public places of high and low densities is proposed. The model works under various scene conditions and with no prior knowledge. A Deep CNN model (DCNN) is built based on convolutional neural network (CNN) structure with small kernel size and two fronts. To increase the efficiency of the model, a convolutional neural network (CNN) as the front-end and a multi-column layer with Dilated Convolution as the back-end were chosen. Also, the proposed method accepts images of arbitrary sizes/scales as inputs from different cameras. To evaluate the proposed model, a dataset was created from images of Saudi people with traditional and non-traditional Saudi outfits. The model was also trained and tested on some existing datasets. Compared to current counting methods, the results show that the proposed model has significantly improved efficiency and reduced the error rate. We achieve the lowest MAE by 67%, 32% .and 15.63% and lowest MSE by around 47%, 15% and 8.1% than M-CNN, Cascaded-MTL, and CSRNet respectively.     

A long acting ophthalmic gel formulations of atenolol

The main aim of pharmacotherapeutics, is the attainment of an effective drug concentration at the intended site of action for a sufficient period of time to elicit the response. In this study a trial was made to formulate atenolol, which is a beta-adrenergic blocker in a topical ophthalmic gel. Two polymers were used in this study, carboxymethylcellulose and sodium alginate in different concentrations. Atenolol was used in concentrations 0.5, 1, and 1.5% w/v. The in vitro release study was carried out. The results showed that the release rate of atenolol from gel preparations decreased as an inverse function of polymer concentration, while the release rate of the drug increased as the initial concentration increased. The data of drug release from the two polymers in different concentrations was plotted against the square root of time, and the diffusion coefficients (D), were calculated from the slope of the equation.

Intra-ocular pressure (IOP) measurements of the rabbit's eye treated with 1% w/v atenolol solution, and 1% w/v atenolol in two gel formulations with different concentrations of the polymer were determined. The two gel formulations showed that these polymers extended the duration of pressure reducing effect to 8 hr, when compared with atenolol solution. Area above the curve (AAC), maximum response, maximum time of response (t_max), and the duration of action were calculated.

The overall results of this study indicated that the gel formulations of atenolol could be used for the development of a long-acting ophthalmic formulation.