Optimized multi-frequency nonlinear broadband piezoelectric energy harvester designs.

Many electrical devices can be powered and operated by harvesting the wasted energy of the surroundings. This research aims to overcome the challenges of output power with a sharp peak, small bandwidth, and the huge dimensions of the piezoelectric energy harvesters relative to the output power. The aforementioned challenges motivated us to investigate the effect of nonlinearity in the shape (tapered and straight cross-section area) as well as the fixation method (the number of fastened ends) to determine the optimal design with high output power and wide working frequency. This research proposes a novel piezoelectric energy harvester array, where each beam is made up of three fixed beams that are joined together by a center mass. The proposed design produces an output power of 35 mW between 25 and 40 Hz. The output power of the proposed design is 3.24 times more than the conventional designs. The recommended approach is simulated utilizing finite element analysis FEA. Analytical and experimental methods validate the proposed FEA, which exhibits excellent agreement.

Plasma Neutrophil Gelatinase-Associated Lipocalin (2-0) Index: A Precise and Sensitive Predictor of Acute Kidney Injury in Children Undergoing Cardiopulmonary Bypass.

OBJECTIVE: To detect the efficacy of neutrophil gelatinase-associated lipocalin (NGAL) in the early prediction of acute kidney injury (AKI) in children undergoing cardiopulmonary bypass (CPB). METHODS: A prospective observational study was conducted wherein 174 patients, aged 6 to 60 months, with congenital heart disease, undergoing CPB and who had a normal baseline renal function were enrolled. Plasma NGAL measurement was done preoperatively and serially at 2, 12, 24, 36, and 48 hours post-CPB initiation. Patients were classified into 2 groups according to the development of postoperative AKI. RESULTS: Plasma NGAL levels post-CPB were significantly higher in the AKI group compared to the non-AKI group with positive significant correlations between plasma NGAL level and severity of AKI. A rise in plasma NGAL of 500% from its preoperative basal level, when measured at 2 hours post-CPB initiation (NGAL 2-0 index), showed sensitivity and specificity of 83% and 64%, respectively (AUC = 0.667) and at 12 hours post-CPB initiation (NGAL 12-0 index) showed sensitivity and specificity of 66% and 64% respectively (AUC = 0.762). CONCLUSION: Plasma NGAL is a predictive biomarker for acute kidney injury after pediatric cardiac surgery. A 500% rise in plasma NGAL at 2 hours post-CPB initiation from its basal preoperative level (NGAL 2-0 index) is a precise, sensitive, and early predictor of AKI in children.

Synthesis and characterization of mussel-inspired nanocomposites based on dopamine-chitosan-iron oxide for wound healing: In vitro study.

There are many challenges faced the soft tissue adhesives in the medical application field. For example, there is a limited effective binding between the medical adhesive and different types of soft tissues. Chitosan (CS) and dopamine (DA) were used as structural units for synthesizing nanocomposites utilized as a wet tissue adhesive. To produce dopamine-chitosan-iron oxide nanocomposites (DA-CS-Fe3O4 NCs), DA was loaded onto chitosan-iron oxide nanocomposites. The nanocomposites have been prepared using ionic gelation method under vigorous homogenization and characterized by different techniques. Fourier-transform infrared spectroscopy (FTIR) have shown that DA-CS- Fe3O4 NCs could attach to the tissue through two possible functional groups, namely, the catechol and amine groups. The results of in vitro scratch wound-healing assay suggested that the prepared DA-CS- Fe3O4 NCs facilitate cell migration (the wound-closure percentage reached 96% at 72 h). All experimental results confirm that DA-CS- Fe3O4 NCs are strongly recommended for use as a soft medical tissue adhesive in wound healing and surgeries such as vascular surgery. In addition, the results of the whole blood clotting, antibacterial assessment, live and dead assay, cytotoxicity test, and wound-healing assay indicate that DA-CS-Fe3O4 NCs can be used as a multifunctional biomedical adhesive.

Alogliptin attenuates cyclophosphamide-induced nephrotoxicity: a novel therapeutic approach through modulating MAP3K/JNK/SMAD3 signaling cascade.

Cyclophosphamide (CP) is widely used as a chemotherapy against various types of cancers. However, CP is accompanied with multiple organ toxicity due to production of reactive oxygen species (ROS), induction of inflammation and consequently apoptosis. Alogliptin (Alo) is a dipeptidyl peptidase 4 (DPP-IV) inhibitor, which is booming as an antidiabetic agent. Interestingly, gliptins are currently studied for their counter-regulatory effects against oxidative stress and inflammation via multiple pathways, among which is the mitogen-activated protein kinase (MAPK)/c-Jun N-terminal kinase (JNK) pathway. This cascade can reduce inflammation via mitigating the activity of mothers against decapentaplegic homolog 3 (SMAD3) and c-Jun. However, Alo effect against CP-induced kidney injury has not been previously elucidated. This tempted us to investigate the possible beneficial effect of Alo against CP-induced kidney injury via modulating the MAP3K/JNK/SMAD3 signaling cascade. Thirty-two male Wistar rats were randomly allocated into four groups. CP-treated group received a single dose of CP (200 mg/kg; i.p.). Alo-treated group received Alo (20 mg/kg/day; p.o.) for 7 days with single CP injection on day 2. Marked decrease in renal injury was observed upon Alo treatment, as evidenced through declined serum kidney function markers, oxidative stress and apoptosis markers, MAP3K expression, phospho (p)-SMAD3, p-JNK, and p-c-Jun levels. These cellular effects were reflected in reduced transforming growth factor beta (TGF-ß) and tumor necrosis factor alpha (TNF-α) fibrotic and inflammatory mediators, coinciding with improved histopathological portrait. In conclusion, the current study provides novel application of Alo as a therapeutic modality against CP-induced nephrotoxicity.

Characterization of the mechanical and structural properties of PGA/TMC copolymer for cardiac tissue engineering.

Recently, scientific research has confirmed that a single polymer material cannot meet the ambitions of all surgical requirements. Thus, combinations of different types of polymeric materials are used in order to manufacture different suture materials. A copolymer of Polyglycolide (PGA) and trimethylene carbonate (TMC) is one of the simplest bioabsorbable monofilament sutures. The optical properties of PGA/TMC copolymer surgical suture were investigated by using multiple-beam interferometric of Fizeau type. The mechanical properties were measured by a suture-drawing apparatus attached to the multiple-beam interferometric system. The refractive indices, stress-strain curve, elastic shear modulus, Young's modulus and crosslink density were investigated for the PGA/TMC surgical suture at various draw ratios. The biological activities were conducted by Quantitative Structure Activity Relationships (QSAR) descriptors. Molecular Electrostatic Potential (MESP) maps were used to describe the reactivity and functional active sites for the given molecule. The behavior of stress-strain curve confirms the compatibility of the suture with the sternum which proves that this suture is a good candidate for cardiac operations. RESEARCH HIGHLIGHTS: Fizeau fringes is accurate in characterizing properties of PGA/TMC surgical suture. The biological activities were conducted by (QSAR) descriptors. The compatibility measurements lead to it is a good candidate for cardiac operations.