The filling of channels in porous media with particles of a material can be interpreted in a first approximation as a packing of spheres in cylindrical recipients. Numerous studies on micro- and nanoscopic scales show that they are, as a rule, not ideal cylinders. In this paper, the channels, which have an irregular shape and a circular cross-section, as well as the packing algorithms are investigated. Five patterns of channel shapes are detected to represent any irregular porous structures. A novel heuristic packing algorithm for monosized spheres and different irregularities is proposed. It begins with an initial configuration based on an fcc unit cell and the subsequent densification of the obtained structure by shaking and gravity procedures. A verification of the algorithm was carried out for nine sinusoidal axisymmetric channels with different D_min/D_max ratio by MATLAB^® simulations, reaching a packing fraction of at least 0.67 (for sphere diameters of 5%D_min or less), superior to a random close packing density. The maximum packing fraction was 73.01% for a channel with a ratio of D_min/D_max = 0.1 and a sphere size of 5%D_min. For sphere diameters of 50%D_min or larger, it was possible to increase the packing factor after applying shaking and gravity movements.

The incidence of cardiovascular diseases is rising, so more people are requiring cardiac services. The private service is very expensive; hence the public health sector capacity is exceeded to accomplish this demand. A proposal to solve this problem is the implementation of a wireless network based on Bluetooth (BT) for recording, monitoring and analysis of electrocardiographic signals (ECG). Three surface electrodes are placed on the chest, following standardized points of triangle of Einthoven. The signals measured are amplified and filtered by components in a circuit and then they are carried to Arduino UNO card. The ECG signal is sent by BT from Arduino UNO to a mobile device carried by the user, so he can send it to a workstation where the ECG is processed or analyzed by an expert. This proposal would help the health sector to improve the quality of their service in the care of patients with heart diseases; also costs of health care would significantly decrease.

Some factors that have increased cardiovascular incidents are sedentary lifestyle, poor eating habits, smoking, stress; hence the importance of continuously monitor cardiac activity in people. This research proposes the implementation of a wireless system to monitor the heart allowing visualization of the electrocardiogram (ECG) on a mobile device via Bluetooth (BT) technology and Arduino UNO board. With this system, patients can monitor and control their cardiac health, resolving the problem of overcrowding in hospitals especially public sector. As a result, the ECG system operates properly in terms of wireless communication and signal processing, showing reliability parameters that provide its use, such as a suitable instrumentation amplifier which CMRR is above of 89 dB. Also CMRR of the overall system accomplishes the minimum of 60 dB, established by the Association for the Advancement of Medical Instrumentation (AAMI) for ambulatory systems; besides the ECG system own a good Signal to Noise Ratio (SNR) above 12 dB when the circuit is powered by batteries.

The incidence of cardiovascular diseases is rising, so more people are requiring cardiac services. The private service is very expensive; hence the public health sector is exceeded by their capacity to accomplish this demand. The proposal to solve this problem is the implementation of a wireless network based on Bluetooth (BT) for recording, monitoring and analysis of electrocardiographic signals (ECG). Three surface electrodes are placed on the chest following standardized points of triangle of Einthoven. The signals measured by electrodes are carried to Arduino UNO card, which works as an instrumentation amplifier. Then ECG signal is sent by BT from Arduino Uno to a mobile device carried by the user, so he can send it to a workstation where the ECG is processed or analyzed by an expert. This proposal would help the health sector to improve the quality of their service in the care of patients with heart diseases; also costs of care would significantly decrease.

The authors have found two errors in the paper published in Materials