Predicting degradation rate of genipin cross-linked gelatin scaffolds with machine learning

Genipin can improve weak mechanical properties and control high degradation rate of gelatin, as a cross-linker of gelatin which is widely used in tissue engineering. In this study, genipin cross-linked gelatin biodegradable porous scaffolds with different weight percentages of gelatin and genipin were prepared for tissue regeneration and measurement of their various properties including morphological characteristics, mechanical properties, swelling, degree of crosslinking and degradation rate. Results indicated that the sample containing the highest amount of gelatin and genipin had the highest degree of crosslinking and increasing the percentage of genipin from 0.125% to 0.5% enhances ultimate tensile strength (UTS) up to 113% and 92%, for samples with 2.5% and 10% gelatin, respectively. For these samples, increasing the percentage of genipin, reduce their degradation rate significantly with an average value of 124%. Furthermore, experimental data are used to develop a machine learning model, which compares artificial neural networks (ANN) and kernel ridge regression (KRR) to predict degradation rate of genipin-cross-linked gelatin scaffolds as a property of interest. The predicted degradation rate demonstrates that the ANN, with mean squared error (MSE) of 2.68%, outperforms the KRR with MSE = 4.78% in terms of accuracy. These results suggest that machine learning models offer an excellent prediction accuracy to estimate the degradation rate which will significantly help reducing experimental costs needed to carry out scaffold design.

Microfluidic centrifugation assisted precipitation based DNA quantification

Nucleic acid amplification methods are increasingly being used to detect trace quantities of DNA in samples for various diagnostic applications. However, quantifying the amount of DNA from such methods often requires time consuming purification, washing or labeling steps. Here, we report a novel microfluidic centrifugation assisted precipitation (μCAP) method for single-step DNA quantification. The method is based on formation of a visible precipitate, which can be quantified, when an intercalating dye (GelRed) is added to the DNA sample and centrifuged for a few seconds. We describe the mechanism leading to the precipitation phenomenon. We utilize centrifugal microfluidics to precisely control the formation of the visible and quantifiable mass. Using a standard CMOS sensor for imaging, we report a detection limit of 45 ng μl-1. Furthermore, using an integrated lab-on-DVD platform we recently developed, the detection limit is lowered to 10 ng μl-1, which is comparable to those of current commercially available instruments for DNA quantification. As a proof of principle, we demonstrate the quantification of LAMP products for a HIV-1B type genome containing plasmid on the lab-on-DVD platform. The simple DNA quantification system could facilitate advanced point of care molecular diagnostics.

Development of strong and bioactive calcium phosphate cement as a light-cure organic-inorganic hybrid

In this research, light cured calcium phosphate cements (LCCPCs) were developed by mixing a powder phase (P) consisting of tetracalcium phosphate and dicalcium phosphate and a photo-curable resin phase (L), mixture of hydroxyethylmethacrylate (HEMA)/poly acrylic-maleic acid at various P/L ratios of 2.0, 2.4 and 2.8 g/mL. Mechanical strength, phase composition, chemical groups and microstructure of the cured cements were evaluated at pre-set times, i.e. before and after soaking in simulated body fluid (SBF). The proliferation of Rat-derived osteoblastic cells onto the LCCPCs as well as cytotoxicity of cement extracts were determined by cell counting and 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazolium bromide assay after different culture times. It was estimated from Fourier transforming infrared spectra of cured cements that the setting process is ruled by polymerization of HEMA monomers as well as formation of calcium poly-carboxylate salts. Microstructure of the cured cements consisted of calcium phosphate particles surrounded by polymerized resin phase. Formation of nano-sized needlelike calcium phosphate phase on surfaces of cements with P/L ratios of 2.4 and 2.8 g/mL was confirmed by scanning electron microscope images and X-ray diffractometry (XRD) of the cured specimen soaked in SBF for 21 days. Also, XRD patterns revealed that the formed calcium phosphate layer was apatite phase in a poor crystalline form. Biodegradation of the cements was confirmed by weight loss, change in molecular weight of polymer and morphology of the samples after different soaking periods. The maximum compressive strength of LCCPCs governed by resin polymerization and calcium polycarboxylate salts formation was about 80 MPa for cement with P/L ratio of 2.8 g/mL, after incubation for 24 h. The strength of all cements decreased by decreasing P/L ratio as well as increasing soaking time. The preliminary cell studies revealed that LCCPCs could support proliferation of osteoblasts cultured on their surfaces and no cytotoxic effect was observed for the extracts of them.

High-yield Synthesis of Multiwalled Carbon Nanotube by Mechanothermal Method

This study reports on the mechanothermal synthesis of multiwalled carbon nanotube (MWCNTs) from elemental graphite powder. Initially, high ultra-active graphite powder can be obtained by mechanical milling under argon atmosphere. Finally, the mechanical activation product is heat-treated at 1350 degrees C for 2-4 h under argon gas flow. After heat-treatment, active graphite powders were successfully changed into MWCNTs with high purity. The XRD analyses showed that in the duration 150 h of milling, all the raw materials were changed to the desired materials. From the broadening of the diffraction lines in the XRD patterns, it was concluded that the graphite crystallites were nanosized, and raising the milling duration resulted in the fineness of the particles and the increase of the strain. The structure and morphology of MWCNTs were investigated using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The yield of MWCNTs was estimated through SEM and TEM observations of the as-prepared samples was to be about 90%. Indeed, mechanothermal method is of interest for fundamental understanding and improvement of commercial synthesis of carbon nanotubes (CNTs). As a matter of fact, the method of mechanothermal guarantees the production of MWCNTs suitable for different applications.

Optical nitrite sensor based on chemical modification of a polymer film

A new, low-cost nitrite sensor was developed by immobilizing a direct indicator dye in an optical sensing film for food and environmental monitoring. This sensor was fabricated by binding gallocyanine to a cellulose acetate film that had previously been subjected to an exhaustive base hydrolysis. The membrane has good durability (>6 months) and a short response time (<7 s). Nitrite can be determined for the range 0.008-1.50 microg/ml with 3delta detection limits of 1 ng/ml. The method is easy to perform and uses acetylcellulose as a carrier. The reagents used for activating the cellulose support are inexpensive, non-toxic and widely available.

[Malnutrition at an internal medicine service: impact of patients coming from homes for the elderly]

OBJECTIVES

To compare nutritional state of patients referred from nursing homes (NH) and patients coming from their own home.

PATIENTS AND METHODS

Several variables were recorded from patients being admitted to an internal medicine ward for a month. Sixty-six patients were included (36 women and 30 men). The mean age of studied patients was 75.7 +/- 14.4 years.

RESULTS

Patients referred from NH had a tricipital skin fold (11.7 +/- 7.5 mm) thinner than patients coming from their home (14.4 +/- 6.5 mm, p = 0.08). Plasma albumin levels were lower in patients with advanced cancer (3 +/- 0.6 g/dl) than in remainder patients (3.2 +/- 0.6 g/dl, p > 0.05). Patients being fed by nasogastric tube had lower plasma levels (2.6 +/- 0.5) than any other patients (3.3 +/- 0.6, p = 0.03). In patients coming from their own home, febrile diseases were associated with a thinner tricipital skin fold and lower plasmatic albumin.

CONCLUSIONS

Patients referred from NH and patients being fed by nasogastric tube presented a deficient protein-energy nutritional state. Febrile diseases were associated with a deficient nutritional state in patients coming from their own home.

Flow injection spectrophotometric determination of ultra trace amounts of oxalic acid

A new simple, sensitive and rapid catalytic-spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between dichromate and Brilliant cresyl blue in acidic media by means of a flow injection analysis method. The color change of Brilliant cresyl blue due to its oxidation was monitored spectrophotometrically at 625 nm. The calibration graph was linear in the range of 0.020-4.70 microg/mL oxalic acid with a limit of detection 0.005 microg/mL of oxalic acid. The relative standard deviation for ten replicate measurements of 0.020 microg/mL and 0.900 microg/mL was 2.2% and 1.7%, respectively. No serious interference was identified. Oxalic acid was determined in wastewater and in spinach by the proposed method with satisfactory results.