Chemiresistors Based on Hybrid Nanostructures Obtained from Graphene and Conducting Polymers with Potential Use in Breath Methane Detection Associated with Irritable Bowel Syndrome.

This paper describes the process of producing chemiresistors based on hybrid nanostructures obtained from graphene and conducting polymers. The technology of graphene presumed the following: dispersion and support stabilization based on the chemical vapor deposition technique; transfer of the graphene to the substrate by spin-coating of polymethyl methacrylate; and thermal treatment and electrochemical delamination. For the process at T = 950 °C, a better settlement of the grains was noticed, with the formation of layers predominantly characterized by peaks and not by depressions. The technology for obtaining hybrid nanostructures from graphene and conducting polymers was drop-casting, with solutions of Poly(3-hexylthiophene (P3HT) and Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-bithiophene] (F8T2). In the case of F8T2, compared to P3HT, a 10 times larger dimension of grain size and about 7 times larger distances between the peak clusters were noticed. To generate chemiresistors from graphene-polymer structures, an ink-jet printer was used, and the metallization was made with commercial copper ink for printed electronics, leading to a structure of a resistor with an active surface of about 1 cm2. Experimental calibration curves were plotted for both sensing structures, for a domain of CH4 of up to 1000 ppm concentration in air. A linearity of the curve for the low concentration of CH4 was noticed for the graphene structure with F8T2, presenting a sensitivity of about 6 times higher compared with the graphene structure with P3HT, which makes the sensing structure of graphene with F8T2 more feasible and reliable for the medical application of irritable bowel syndrome evaluation.

Identification and Evaluation of Non-Accidental Trauma in the Pediatric Population: A Clinical Review.

Non-accidental trauma (NAT) is a major cause of morbidity and mortality for children around the world and most significantly impacts children under one year of age. Prompt and comprehensive treatment of these children relies on a high index of suspicion from any medical provider that treats pediatric patients. This review discusses those most at risk for experiencing NAT, and common initial presentations, to assist providers in the identification of potential victims. In addition, this review provides guidance on the recommended workup for these patients so that the full extent of associated injuries may be identified and the appropriate healthcare team may be assembled.

The performance of artificial intelligence large language model-linked chatbots in surgical decision-making for gastroesophageal reflux disease.

BACKGROUND: Large language model (LLM)-linked chatbots may be an efficient source of clinical recommendations for healthcare providers and patients. This study evaluated the performance of LLM-linked chatbots in providing recommendations for the surgical management of gastroesophageal reflux disease (GERD). METHODS: Nine patient cases were created based on key questions addressed by the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) guidelines for the surgical treatment of GERD. ChatGPT-3.5, ChatGPT-4, Copilot, Google Bard, and Perplexity AI were queried on November 16th, 2023, for recommendations regarding the surgical management of GERD. Accurate chatbot performance was defined as the number of responses aligning with SAGES guideline recommendations. Outcomes were reported with counts and percentages. RESULTS: Surgeons were given accurate recommendations for the surgical management of GERD in an adult patient for 5/7 (71.4%) KQs by ChatGPT-4, 3/7 (42.9%) KQs by Copilot, 6/7 (85.7%) KQs by Google Bard, and 3/7 (42.9%) KQs by Perplexity according to the SAGES guidelines. Patients were given accurate recommendations for 3/5 (60.0%) KQs by ChatGPT-4, 2/5 (40.0%) KQs by Copilot, 4/5 (80.0%) KQs by Google Bard, and 1/5 (20.0%) KQs by Perplexity, respectively. In a pediatric patient, surgeons were given accurate recommendations for 2/3 (66.7%) KQs by ChatGPT-4, 3/3 (100.0%) KQs by Copilot, 3/3 (100.0%) KQs by Google Bard, and 2/3 (66.7%) KQs by Perplexity. Patients were given appropriate guidance for 2/2 (100.0%) KQs by ChatGPT-4, 2/2 (100.0%) KQs by Copilot, 1/2 (50.0%) KQs by Google Bard, and 1/2 (50.0%) KQs by Perplexity. CONCLUSIONS: Gastrointestinal surgeons, gastroenterologists, and patients should recognize both the promise and pitfalls of LLM's when utilized for advice on surgical management of GERD. Additional training of LLM's using evidence-based health information is needed.

Unveiling the Dynamic Self-Assembly of a Recombinant Dragline-Silk-Mimicking Protein.

Despite the considerable interest in the recombinant production of synthetic spider silk fibers that possess mechanical properties similar to those of native spider silks, such as the cost-effectiveness, tunability, and scalability realization, is still lacking. To address this long-standing challenge, we have constructed an artificial spider silk gene using Golden Gate assembly for the recombinant bacterial production of dragline-mimicking silk, incorporating all the essential components: the N-terminal domain, a 33-residue-long major-ampullate-spidroin-inspired segment repeated 16 times, and the C-terminal domain (N16C). This designed silk-like protein was successfully expressed in Escherichia coli, purified, and cast into films from formic acid. We produced uniformly 13C-15N-labeled N16C films and employed solid-state magic-angle spinning nuclear magnetic resonance (NMR) for characterization. Thus, we could demonstrate that our bioengineered silk-like protein self-assembles into a film where, when hydrated, the solvent-exposed layer of the rigid, ß-nanocrystalline polyalanine core undergoes a transition to an α-helical structure, gaining mobility to the extent that it fully dissolves in water and transforms into a highly dynamic random coil. This hydration-induced behavior induces chain dynamics in the glycine-rich amorphous soft segments on the microsecond time scale, contributing to the elasticity of the solid material. Our findings not only reveal the presence of structurally and dynamically distinct segments within the film's superstructure but also highlight the complexity of the self-organization responsible for the exceptional mechanical properties observed in proteins that mimic dragline silk.

Decision-Making in Pleural Drainage Following Lung Resection in Children: A Western Pediatric Surgery Research Consortium Survey.

INTRODUCTION: Studies of adults undergoing lung resection indicated that selective omission of pleural drains is safe and advantageous. Significant practice variation exists for pleural drainage practices for children undergoing lung resection. We surveyed pediatric surgeons in a 10-hospital research consortium to understand decision-making for placement of pleural drains following lung resection in children. METHODS: Faculty surgeons at the 10 member institutions of the Western Pediatric Surgery Research Consortium completed questionnaires using a REDCap survey platform. Descriptive statistics and bivariate analyses were used to characterize responses regarding indications and management of pleural drains following lung resection in pediatric patients. RESULTS: We received 96 responses from 109 surgeons (88 %). Most surgeons agreed that use of a pleural drain after lung resection contributes to post-operative pain, increases narcotic use, and prolongs hospitalization. Opinions varied around the immediate use of suction compared to water seal, and half routinely completed a water seal trial prior to drain removal. Surgeons who completed fellowship within the past 10 years left a pleural drain after wedge resection in 45 % of cases versus 78 % in those who completed fellowship more than 10 years ago (p = 0.001). The mean acceptable rate of unplanned post-operative pleural drain placement when pleural drainage was omitted at index operation was 6.3 % (±4.6 %). CONCLUSIONS: Most pediatric surgeons use pleural drainage following lung resection, with recent fellowship graduates more often omitting it. Future studies of pleural drain omission demonstrating low rates of unplanned postoperative pleural drain placement may motivate practice changes for children undergoing lung resection. LEVEL OF EVIDENCE: V.

Evaluating Outcomes of Nonaccidental Trauma in Military Children.

BACKGROUND: Nonaccidental trauma (NAT), or child abuse, is a leading cause of childhood injury and death in the US. Studies demonstrate that military-affiliated individuals are at greater risk of mental health complication and family violence, including child maltreatment. There is limited information about the outcomes of military children who experience NAT. This study compares the outcomes between military-dependent and civilian children diagnosed with NAT. STUDY DESIGN: A single-institution, retrospective review of children admitted with confirmed NAT at a Level I trauma center was performed. Data were collected from the institutional trauma registry and the Child Abuse Team's database. Military affiliation was identified using insurance status and parental or caregiver self-reported active-duty status. Demographic and clinical data including hospital length of stay (LOS), morbidity, specialty consult, and mortality were compared. RESULTS: Among 535 patients, 11.8% (n = 63) were military-affiliated. The median age of military-associated patients, 3 months (interquartile range [IQR] 1 to 7), was significantly younger than civilian patients, 7 months (IQR 3 to 18, p < 0.001). Military-affilif:ated patients had a longer LOS of 4 days (IQR 2 to 11) vs 2 days (IQR 1 to 7, p = 0.041), increased morbidity or complication (3 vs 2 counts, p = 0.002), and a higher mortality rate (10% vs 4%, p = 0.048). No significant difference was observed in the number of consults or injuries, trauma activation, or need for surgery. CONCLUSIONS: Military-affiliated children diagnosed with NAT experience more adverse outcomes than civilian patients. Increased LOS, morbidity or complication, and mortality suggest military-affiliated patients experience more life-threatening NAT at a younger age. Larger studies are required to further examine this population and better support at-risk families.

Outcomes of Extracorporeal Life Support Utilization for Pediatric Patients With COVID-19 Infections.

Outcomes of pediatric patients who received extracorporeal life support (ECLS) for COVID-19 remain poorly described. The aim of this multi-institutional retrospective observational study was to evaluate these outcomes and assess for prognostic factors associated with in-hospital mortality. Seventy-nine patients at 14 pediatric centers across the United States who received ECLS support for COVID-19 infections between January 2020 and July 2022 were included for analysis. Data were extracted from the electronic medical record. The median age was 14.5 years (interquartile range [IQR]: 2-17 years). Most patients were female (54.4%) and had at least one pre-existing comorbidity (84.8%), such as obesity (44.3%, median body mass index percentile: 97% [IQR: 67.5-99.0%]). Venovenous (VV) ECLS was initiated in 50.6% of patients. Median duration of ECLS was 12 days (IQR: 6.0-22.5 days) with a mean duration from admission to ECLS initiation of 5.2 ± 6.3 days. Survival to hospital discharge was 54.4%. Neurological deficits were reported in 16.3% of survivors. Nonsurvivors were of older age (13.3 ± 6.2 years vs. 9.3 ± 7.7 years, p = 0.012), more likely to receive renal replacement therapy (63.9% vs. 30.2%, p = 0.003), demonstrated longer durations from admission to ECLS initiation (7.0 ± 8.1 days vs. 3.7 ± 3.8 days, p = 0.030), and had higher rates of ECLS-related complications (91.7% vs. 69.8%, p = 0.016) than survivors. Pediatric patients with COVID-19 who received ECLS demonstrated substantial morbidity and further investigation is warranted to optimize management strategies.

Cervical Collar-Associated Pressure Injury in Pediatric Trauma Patients: A Western Pediatric Surgery Research Consortium Study.

BACKGROUND: Healthcare-associated pressure injuries (HAPI) are known to be associated with medical devices and are preventable. Cervical spine immobilization is commonly utilized in injured children prior to clinical clearance or for treatment of an unstable cervical spinal injury. The frequency of HAPI has been quantified in adults with cervical spine immobilization but has not been well-described in children. The aim of this study was to describe characteristics of children who developed HAPI associated with cervical immobilization. METHODS: We analyzed a retrospective cohort of children (0-18 years) who developed a stage two or greater cervical HAPI. This cohort was drawn from an overall sample of 49,218 registry patients treated over a five-year period (2017-2021) at ten pediatric trauma centers. Patient demographics, injury characteristics, and cervical immobilization were tabulated to describe the population. RESULTS: The cohort included 32 children with stage two or greater cervical HAPI. The median age was 5 years (IQR 2-13) and 78% (n = 25) were admitted to the intensive care unit. The median (IQR) time to diagnosis of HAPI was 11 (7-21) days post-injury. The majority of cervical HAPI (78%, 25/32) occurred in children requiring immobilization for cervical injuries, with only four children developing HAPI after wearing a prophylactic cervical collar in the absence of a cervical spine injury. CONCLUSION: Advanced-stage HAPI associated with cervical collar use in pediatric trauma patients is rare and usually occurs in patients with cervical spine injuries requiring immobilization for treatment. More expedient cervical spine clearance with MRI is unlikely to substantially reduce cervical HAPI in injured children. LEVEL OF EVIDENCE: Level III (Epidemiologic and Prognostic).

A Window of Opportunity: Understanding Pediatric Falls Using Area Deprivation Index.

INTRODUCTION: The purpose of our study is to assess neighborhood socioeconomic disadvantage (NSD) as a risk factor for window falls (WF) in children. METHODS: A single institution retrospective review was performed of patients ≤18 years old with fall injuries treated at a Level I trauma center between 2018 and 2021. Demographic, injury, and NSD characteristics which were collected from a trauma registry were analyzed and compared between WF versus non-window falls. Area Deprivation Index (ADI) was used to measure NSD levels based on patients' home address 9-digit zip code, with greater NSD being defined as ADI quintiles 4 and 5. Property type was used to compare falls that took place at single-family homes versus apartment buildings. RESULTS: Among 1545 pediatric fall injuries, 194 were WF, of which 60 % were male and 46 % were Hispanic. WF patients were younger than NWF patients (median age WF 3.2 vs. age 4.3, p<0.047). WF patients were more likely to have a depressed Glasgow Coma Scale (GCS score ≤12, WF 9 % vs. 3 %) and sustain greater head/neck injuries (median AIS 3vs. AIS 2, p<0.001) when compared to NWF. WF patients had longer hospital and ICU lengths of stay than NWF patients (p<0.001 and p<0.001, respectively). WF patients were more likely to live in areas of greater NSD than NWF patients (53 % vs. 35 %, p<0.001), and 73 % of all WF patients lived in apartments or condominiums. CONCLUSIONS: Window fall injuries were associated with lower GCS, greater severity of head/neck injuries, and longer hospital and ICU length of stay than non-window falls. ADI research can provide meaningful data for targeted injury prevention programs in areas where children are at higher risk of window falls. STUDY TYPE: Retrospective review. LEVEL OF EVIDENCE: III.

A Comparative Study of Laparoscopic versus Open Management of Index Small Bowel Obstruction in Children.

INTRODUCTION: There is limited literature on the optimal approach to treat adhesive small bowel obstruction (ASBO) in children. We sought to compare rates and outcomes of laparoscopic (LAP) and open (OPEN) surgery for pediatric ASBO. METHODS: A California statewide database was used to identify children (<18 years old) with an index ASBO from 2007 to 2020. The primary outcome was the type of operative management: LAP or OPEN. Secondary outcomes were hospital characteristics, patient demographics, and postoperative complications. We excluded patients treated non-operatively. RESULTS: Our study group had 545 patients. 381 (70%) underwent OPEN and 164 (30%) LAP during the index admission. Over the study period, there was increasing use of laparoscopic surgery, with higher use in older children (p < 0.001). LAP was associated with fewer overall complications (65.2% vs. 81.6%, p < 0.001), with a decreasing trend in complications over time (p < 0.001). The LAP group had significantly lower rates of bowel resection (4.9% vs. 17.1%, p < 0.001), length of stay (LOS) (17 vs. 23 days, p < 0.001), and TPN use (12.2% vs. 29.1%, p < 0.001). Mortality rates were equivalent. Although the LAP group had lower readmission rates (22.6% vs. 37.3%, p < 0.001), the length of time between discharge and readmission was similar (171 vs. 165 days, p = 0.190). DISCUSSION: The use of laparoscopic surgery for index ASBO increased over the study period. However, it was less commonly utilized in younger children. LAP had fewer overall complications as well as shorter LOS, decreased TPN use, and fewer readmissions. The benefits and risks of each approach must be weighed. LEVEL OF EVIDENCE: III.

Application of a Machine Learning Algorithm in Prediction of Abusive Head Trauma in Children.

PURPOSE: We explored the application of a machine learning algorithm for the timely detection of potential abusive head trauma (AHT) using the first free-text note of an encounter and demographic information. METHODS: First free-text physician notes and demographic information were collected for children under 5 years of age at a Level 1 Trauma Center. The control group, which included patients with head/neck injury, was compared to those with AHT diagnosed by the Child Protective Team. Differential scores accounted for words overrepresented in AHT patient vs. control notes. Sentiment scores were reflective of note positivity/negativity and subjectivity scores accounted for note subjectivity/objectivity. The composite scores reflected the patient's differential score modified by the subjectivity score. Composite, sentiment, and subjectivity scores combined with demographic information trained a Random Forest (RF) machine learning algorithm to predict AHT. RESULTS: Final composite scores with demographic information were highly associated with AHT in a test dataset. The control group included 587 patients and the test group included 193 patients. Combining composite scores with demographic information into the RF model improved AHT classification area under the curve (AUC) from 0.68 to 0.78, with an overall accuracy of 84%. Feature importance analysis of our RF model revealed that composite score, sentiment, age, and subjectivity were the most impactful predictors of AHT. The sentiment was not significantly different between control and AHT notes (p = 0.87), while subjectivity trended higher for AHT notes (p = 0.081). CONCLUSION: We conclude that a machine learning algorithm can recognize patterns within free-text notes and demographic information that aid in AHT detection in children. LEVEL OF EVIDENCE: III.

Factors Associated with Postoperative Opioid Use in Adolescents.

BACKGROUND: We aimed to identify factors associated with postoperative prescription opioid use in adolescents. METHODS: Adolescents aged 13-20 years undergoing surgery were prospectively recruited from a children's hospital. Adolescent-parent dyads completed a preoperative survey, measuring clinical and sociodemographic factors, and two postoperative surveys evaluating self-reported opioid use at 30- and 90-days. Poisson regression analysis identified factors associated with the number of pills used within 90-days, adjusting for age, gender, race/ethnicity, surgery type, and pain at discharge. RESULTS: We enrolled 119 adolescents who reported postoperative opioid use following posterior spinal fusion (PSF) (50 %), arthroscopy (23 %), pectus excavatum repair (11 %), tonsillectomy (8 %), and hip reconstruction (7 %). Overall, 81 % of adolescents reported unused opioids. The median pain score at discharge was 7 (IQR:5-8). Adolescents reported using a median of 7 (IQR:2-15) opioid pills, with 20 (IQR:7-30) pills left unused. Compared to all other surgeries, adolescents undergoing PSF reported the highest median pill use (10, IQR:5-29; p = 0.004). Adolescents undergoing tonsillectomy reported the lowest median pill use (1, IQR:0-7; p = 0.03). On regression analysis, older patient age was associated with a 12 % increase in pill use (95 % CI:3%-23 %). Undergoing PSF was associated with a 63 % increase in pill use (95 % CI:15%-31 %). Each additional pain scale point reported at discharge was associated with a 13 % increase in pill use (95 % CI:5%-22 %). CONCLUSIONS: Older age, surgery type, and patient-reported pain at discharge are associated with postoperative prescription opioid use in adolescents. Understanding patient and surgery-specific factors associated with opioid use may guide surgeons to minimize excess opioid prescribing. LEVEL OF EVIDENCE: II.

Thermoplastic Electromagnetic Shielding Materials from the Integral Recycling of Waste from Electronic Equipment.

The European Green Deal's goals are anticipated to be fulfilled in large part thanks to the New Circular Economy Action Plan. It is believed that recycling materials will have a significant positive impact on the environment, particularly in terms of reducing greenhouse gas emissions and the impacts this will have on preventing climate change. Due to the complexity of the issue and its significant practical ramifications, the activity of Waste Electrical and Electronic Equipment (WEEE) collection networks is a subject of interest for researchers and managers, in accordance with the principles that recent laws have addressed in a large number of industrialized countries. The goal of this paper is to characterize and obtain composite materials using an injection process with a matrix of LDPE, PP, and HDPE, with up to a 10% addition of nonmetallic powders from PCBs and electronic parts from an integrated process of WEEE recycling. The composites present relevant thermal, electrical, and mechanical properties. Such composite materials, due to their relevant dielectric properties, may be further tested for applications in electromagnetic shielding at frequencies above 1 kHz, or for electromagnetic interference/electromagnetic compatibility (EMI/EMC and ESD) applications at lower frequencies due to their superior dielectric loss factor values, associated with relevant behaviors around exploitation temperatures, mainly for the electric, electronic, or automotive industries.

Trends in Management of Index Adhesive Small Bowel Obstruction in Children.

INTRODUCTION: To examine practice patterns and surgical outcomes of nonoperative versus operative management (OPM) of children presenting with an index adhesive small bowel obstruction (ASBO). METHODS: A California statewide health discharge database was used to identify children (<18 y old) with an index ASBO from 2007 to 2020. The primary study outcome was evaluating initial management patterns (nonoperative versus OPM and early [≤3 d] versus late surgery [>3 d]) of ASBO. Secondary outcomes were hospital characteristics, patient demographics, and postoperative complications. RESULTS: Of the 2297 patients identified, 1948 (85%) underwent OPM for ASBO during the index admission. Of these, 14.7% underwent early surgery within 3 d. Teaching hospitals had higher operative intervention than nonteaching centers (87.1% versus 83.7%, P = 0.034). OPM was the highest in 0-5-year-olds compared to other ages (89% versus 82%, P < 0.001). In comparison to early surgery, late surgery was associated with longer length of stay (early 7[interquartile range 5-10], late 9[interquartile range 6-17], P < 0.001), increased infectious complications (16.4% versus 9.8%, P = 0.004), and greater use of total parenteral nutrition (28.0% versus 14.3%, P = 0.001); there was no difference in bowel resection (21% versus 18%, P = 0.102) or mortality (P = 0.423). CONCLUSIONS: Our pediatric study demonstrated a high rate of OPM for index ASBO, especially in newborns and toddlers. Although operative intervention, especially late surgery, was associated with increased length of stay, increased infectious complications, and increased total parenteral nutrition use, the rates of bowel resection and mortality did not differ by management strategy. These trends need to be further evaluated to optimize outcomes.

Machine learning to predict pediatric choledocholithiasis: A Western Pediatric Surgery Research Consortium retrospective study.

BACKGROUND: The purpose of this study was to accurately predict pediatric choledocholithiasis with clinical data using a computational machine learning algorithm. METHODS: A multicenter retrospective cohort study was performed on children <18 years of age who underwent cholecystectomy between 2016 to 2019 at 10 pediatric institutions. Demographic data, clinical findings, laboratory, and ultrasound results were evaluated by bivariate analyses. An Extra-Trees machine learning algorithm using k-fold cross-validation was used to determine predictive factors for choledocholithiasis. Model performance was assessed using the area under the receiver operating characteristic curve on a validation dataset. RESULTS: A cohort of 1,597 patients was included, with an average age of 13.9 ± 3.2 years. Choledocholithiasis was confirmed in 301 patients (18.8%). Obesity was the most common comorbidity in all patients. Choledocholithiasis was associated with the finding of a common bile duct stone on ultrasound, increased common bile duct diameter, and higher serum concentrations of aspartate aminotransferase, alanine transaminase, lipase, and direct and peak total bilirubin. Nine features (age, body mass index, common bile duct stone on ultrasound, common bile duct diameter, aspartate aminotransferase, alanine transaminase, lipase, direct bilirubin, and peak total bilirubin) were clinically important and included in the machine learning algorithm. Our 9-feature model deployed on new patients was found to be highly predictive for choledocholithiasis, with an area under the receiver operating characteristic score of 0.935. CONCLUSION: This multicenter study uses machine learning for pediatric choledocholithiasis. Nine clinical factors were highly predictive of choledocholithiasis, and a machine learning model trained using medical and laboratory data was able to identify children at the highest risk for choledocholithiasis.

Special Packaging Materials from Recycled PET and Metallic Nano-Powders.

The European methodology for plastics, as a feature of the EU's circular economy activity plan, ought to support the decrease in plastic waste. The improvement of recycled plastics' economics and quality is one important part of this action plan. Additionally, achieving the requirement that all plastic packaging sold in the EU by 2030 be recyclable or reusable is an important objective. This means that food packaging materials should be recycled in a closed loop at the end. One of the most significant engineering polymers is polyethylene terephthalate (PET), which is widely used. Due to its numerous crucial qualities, it has a wide variety of applications, from packaging to fibers. The thermoplastic polyolefin, primarily polyethylene and polypropylene (PP), is a popular choice utilized globally in a wide range of applications. In the first phase of the current experiment, the materials were obtained by hot pressing with the press machine. The reinforcer is made of Al nanopowder 800 nm and Fe nanopowder 790 nm and the quality of the recycled polymer was examined using Fourier transform infrared spectroscopy (FTIR), a scanning electron microscope (SEM), and differential scanning calorimetry (DSC). From DSC variation curves as a function of temperature, the values from the transformation processes (glass transition, crystallization, and melting) are obtained. SEM measurements revealed that the polymer composites with Al have smooth spherical particles while the ones with Fe have bigger rough spherical particles.

Flexible Electromagnetic Shielding Nano-Composites Based on Silicon and NiFe2O4 Powders.

In this paper, the obtaining and characterization of five experimental models of novel polymer composite materials with ferrite nano-powder are presented. The composites were obtained by mechanically mixing two components and pressing the obtained mixture on a hot plate press. The ferrite powders were obtained by an innovative economic co-precipitation route. The characterization of these composites consisted of physical and thermal properties: hydrostatic density, scanning electron microscopy (SEM), and TG DSC thermal analyses, along with functional electromagnetic tests in order to demonstrate the functionality of these materials as electromagnetic shields (magnetic permeability, dielectric characteristics, and shielding effectiveness). The purpose of this work was to obtain a flexible composite material, applicable to any type of architecture for the electrical and automotive industry, necessary for protection against electromagnetic interference. The results demonstrated the efficiency of such materials at lower frequencies, but also in the microwave domain, with higher thermal stability and lifetime.

Three-Dimensional Printable Flexible Piezoelectric Composites with Energy Harvesting Features.

The purpose of this work was to obtain an elastic composite material from polymer powders (polyurethane and polypropylene) with the addition of BaTiO3 until 35% with tailored dielectric and piezoelectric features. The filament extruded from the composite material was very elastic but had good features to be used for 3D printing applications. It was technically demonstrated that the 3D thermal deposition of composite filament with 35% BaTiO3 was a convenient process for achieving tailored architectures to be used as devices with functionality as piezoelectric sensors. Finally, the functionality of such 3D printable flexible piezoelectric devices with energy harvesting features was demonstrated, which can be used in various biomedical devices (as wearable electronics or intelligent prosthesis), generating enough energy to make such devices completely autonomous only by exploiting body movements at variable low frequencies.