Limitations Of Devices Research Articles

Performance of a Hydrogel Coated Nitinol with Oligonucleotide-Modified Nanoparticles Within Turbulent Conditions of Blood-Contacting Devices.

Hydrogels offer a wide range of applications in the antithrombotic modification of biomedical devices. The functionalization of these hydrogels with potentially drug-laden nanoparticles in the context of deviceassociated turbulence is critically under-studied. Thus, the purpose of this study was to use a hydrogel-coating nitinol surface as a model to understand the functions of hydrogels and the capture of nanoparticles under clinically relevant flow conditions. Nitinol was coated by an oligonucleotide (ON) functionalized hydrogel. Nanoparticles were functionalized with complementary oligonucleotides (CONs). The capture of CONfunctionalized nanoparticles by the ON-functionalized hydrogel surfaces was studied under both static and dynamic attachment conditions. Fluorescent-labelling of nanoparticles was utilized to assess capture efficacy and resistance to removal by device-relevant flow conditions. The specificity of the ON-CON bond was verified, exhibiting a dose-dependent attachment response. The hydrogel coating was resistant to stripping by flow, retaining >95% after exposure to one hour of turbulent flow. Attachment of nanoparticles to the hydrogel was higher in the static condition than under laminar flow (p < 0.01), but comparable to that of attachment under turbulent flow. Modified nitinol samples underwent one hour of flow treatment under both laminar and turbulent regimes and demonstrated decreased nanoparticle loss following static conjugation rather than turbulent conjugation (36.1% vs 53.8%, p < 0.05). There was no significant difference in nanoparticle functionalization by upstream injection between laminar and turbulent flow. The results demonstrate promising potential of hydrogelfunctionalized nitinol for capturing nanoparticles using nucleic acid hybridization. The hydrogel structure and ONCON bond integrity both demonstrated a resistance to mechanical damage and loss of biomolecular functionalization by exposure to turbulence. Further investigation is warranted to highlight drug delivery and antithrombogenic modification applications of nanoparticle-functionalized hydrogels.

An Assessment of Vape Shop Products in California before and after Implementation of FDA and State Regulations.

Vape shops specialize in sales of e-cigarettes and related products. This study examines whether vape shops adapted their products and services in response to changes in federal and state policies that affect the tobacco retail environment between 2014-2022. In this multicohort study, four waves of study data were used to examine the trends in products sold in vape shops in Southern California. Items sold were assessed through systematic store product observations and included categories of e-cigarettes, device modification equipment, and other products (e.g., Cannabidiol (CBD), paraphernalia). Descriptive statistics are reported. The availability of disposable devices increased from 18% at Wave 1 to 98% of shops at Wave 4. Pod mods were first observed in 79% of the shops beginning at Wave 3. Device modification drills later become obsolete, from 60% at Wave 1 to 0 by Wave 4; self-service sampling displays declined from 83% of shops to 9%. Vape shops did not carry CBD products until Wave 3 (2017/2018), when 19.0% of shops carried CBD products and 72.9% at Wave 4. Future research should examine how e-cigarette retailers and manufacturers respond to changing state and federal regulations to better understand the implications of regulatory efforts.

Deferoxamine-Based Materials and Sensors for Fe(III) Detection

Deferoxamine (DFO) is a siderophore widely studied for its ability to bind iron(III) strongly. Thanks to its versatility, it is suitable for several clinical and analytical applications, from the recognized iron(III) chelation therapy to the most recent applications in sensing. The presence of three hydroxamic functional groups enables Deferoxamine to form stable complexes with iron(III) and other divalent and trivalent metal ions. Moreover, the terminal amino group in the DFO molecule, not involved in metal ion complexation, allows modification or functionalization of solid phases, nanoobjects, biopolymers, electrodes and optical devices. This review summarizes and discusses deferoxamine-based applications for the chelation and recognition of Fe(III).

Oriented Magnetic Fields and Blood Pressure

Hypertension is a combination of genetic, environmental, and social factors, defined by blood pressure levels in which the benefits of treatment outweigh the risks. The global prevalence of hypertension is approximately 1.3 billion adults. The blood pressure control rates in developing countries in 2019 were 23% in women and 18% in men. Treatments range from lifestyle modification, medication treatment, and use of medical devices. The prevalence of resistant arterial hypertension is estimated between 12% to 15% among patients with hypertension. [...]

Polymerization of l-Tyrosine, l-Phenylalanine, and 2-Phenylethylamine as a Versatile Method of Surface Modification for Implantable Medical Devices.

Surface properties are crucial for medical device and implant research and applications. We present novel polycatecholamine coatings obtained by oxidative polymerization of l-tyrosine, l-phenylalanine, and 2-phenylethylamine based on mussel glue-inspired chemistry. We optimized the reaction parameters and examined the properties of coatings compared to the ones obtained from polydopamine. We produced polycatecholamine coatings on various materials used to manufacture implantable medical devices, such as polyurethane, but also hard-to-coat polydimethylsiloxane, polytetrafluoroethylene, and stainless steel. The coating process results in significant hydrophilization of the material's surface, reducing the water contact angle by about 50 to 80% for polytetrafluoroethylene and polyurethane, respectively. We showed that the thickness, roughness, and stability of the polycatecholamine coatings depend on the chemical structure of the oxidized phenylamine. In vitro experiments showed prominent hemocompatibility of our coatings and significant improvement of the adhesion and proliferation of human umbilical vein endothelial cells. The full confluence on the surface of coated polytetrafluoroethylene was achieved after 5 days of cell culture for all tested polycatecholamines, and it was maintained after 14 days. Hence, the use of polycatecholamine coatings can be a simple and versatile method of surface modification of medical devices intended for contact with blood or used in tissue engineering.

Microbial Biosensors for Rapid Determination of Biochemical Oxygen Demand: Approaches, Tendencies and Development Prospects.

One of the main indices of the quality of water is the biochemical oxygen demand (BOD). A little over 40 years have passed since the practical application of the first microbial sensor for the determination of BOD, presented by the Japanese professor Isao Karube. This time span has brought new knowledge to and practical developments in the use of a wide range of microbial cells based on BOD biosensors. At present, this field of biotechnology is becoming an independent discipline. The traditional BOD analysis (BOD5) has not changed over many years; it takes no less than 5 days to carry out. Microbial biosensors can be used as an alternative technique for assessing the BOD attract attention because they can reduce hundredfold the time required to measure it. The review examines the experience of the creation and practical application of BOD biosensors accumulated by the international community. Special attention is paid to the use of multiple cell immobilization methods, signal registration techniques, mediators and cell consortia contained in the bioreceptor. We consider the use of nanomaterials in the modification of analytical devices developed for BOD evaluation and discuss the prospects of developing new practically important biosensor models.

GNSS receiver for Q-Sat and its analysis of precise orbit determination

The Earth's gravity field and upper atmosphere are very important scientific information and their mechanical models can be obtained by inversion of the satellite precision orbit. It would be ideal to develop a constellation of satellites distributed with different orbits to measure atmospheric drag and gravity. Based on this idea, Tsinghua University developed a microsatellite Q-Sat for measuring the gravity field and the density of the upper atmosphere. Low-cost, high-precision measurements can greatly improve the cost effectiveness of scientific missions. In this paper, a spatial modification method for GNSS receivers based on commercial off-the-shelf was proposed. The base module of the receiver is a ground-based general-purpose device, and this modification method allows for the space-batch modification of industrial-grade devices. The modified receiver was successfully applied to the Q-Sat and a large amount of continuous on-orbit data were obtained. Data analysis results show that the receiver can simultaneously receive GPS-L1\\L2 and BD1\\BD2 multifrequency navigation satellite signals in the highly dynamic spatial environment. To reduce the precision orbit determination error, the GNSS observations were corrected by antenna center modelling, and the long-term orbit determination accuracy is stabilized at the centimeter level. The commercial off-the-shelf based GNSS receiver modification method and precision orbit determination strategy can provide a reference for low-cost and high-precision microsatellites.

Toward an intravaginal device to detect risk of preterm labor: a user-centered design approach in Sub-Saharan Africa

BackgroundPrematurity and its complications are the leading cause of death and disability in children under five in Africa and North America, affecting as many as one in ten pregnancies. Screening tests to predict preterm birth (PTB) are insensitive, costly, and often unavailable in low resource settings. In parallel with early-stage U.S.-based testing of a novel self-placed intravaginal device to predict PTB risk, we elicited key stakeholder input from two sub-Saharan African countries to ensure local contextual factors inform future development of the device and its acceptability.MethodsA qualitative study was conducted in Kiambu County, Kenya and KwaZulu-Natal Province, South Africa. We conducted 26 focus group discussions with pregnant women (n = 132) and males from the community (n = 54); in-depth interviews with women who had a history of PTB (n = 10), healthcare providers (n = 16), and health system experts (n = 10). Interviews were transcribed and thematic analysis was performed using an iterative coding technique. In addition, we facilitated user-centered design sessions to generate prototype preferences.ResultsWomen with a personal history of PTB were almost unanimous in support of the proposed device, whereas those with no experience of PTB expressed the greatest degree of reservation. Healthcare providers anticipated that women with a history of PTB would accept the device. However, various potential challenges were identified, including potential discomfort with device insertion, hygiene, and sexual activity, as well as need for provider training, and attention to country-specific regulatory processes. Both community participants and providers expressed a preference for a provider inserted device. Design recommendations included preference for a small, soft, pliable device, with a shape that could facilitate easy removal.ConclusionsUse of an intravaginal device to detect risk of PTB was generally acceptable, however stakeholders expressed a notable preference for insertion by providers. This reflects the significance of end-user consultation in device design and use. Recommended device modifications as well as educational messaging and provider technical assistance may facilitate utilization.

Final safety and efficacy results from a 106 real-world patients registry with an ascites-mobilizing pump.

Background and aimsPatients with cirrhotic refractory ascites ineligible for transjugular intrahepatic shunt (TIPSS) have limited treatment options apart from repeated large volume paracentesis. The alfapump® is an implantable device mobilizing ascites from the peritoneal cavity to the bladder, from where it can be excreted. The aim of this observational cohort study was to prospectively investigate safety and efficacy of the device in a real‐world cohort with cirrhotic refractory ascites and contraindications for TIPSS.MethodsA total of 106 patients received an implant at 12 European centres and were followed up for up to 24 months. Complications, device deficiencies, frequency of paracentesis, clinical status and survival were recorded prospectively.ResultsApproximately half of the patients died on‐study, about a quarter was withdrawn because of serious adverse events leading to explant, a sixth were withdrawn because of liver transplant or recovery, and nine completed follow‐up. The most frequent causes of on‐study death and complication‐related explant were progression of liver disease and infection. The device reduced the requirement for large‐volume paracentesis significantly, with more than half of patients not having required any post‐implant. Survival benefits were not observed. Device‐related reinterventions were predominantly caused by device deficiencies. A post‐hoc comparison of the first 50 versus the last 50 patients enrolled revealed a decreased reintervention rate in the latter, mainly related to peritoneal catheter modifications.ConclusionsThe device reduced paracentesis frequency in a real‐world setting. Technical complications were successfully decreased by optimization of management and device modification (NCT01532427).

A High Efficiency and Precision Smoothing Polishing Method for NiP Coating of Metal Mirror.

The NiP coating has excellent wear and corrosion resistance, and electroless nickel-phosphorus coating is one of the best measures for surface modification of metal optical devices. The NiP layer could be processed by single-point diamond turning (SPDT). However, the periodic marks on the surface of the NiP coating processed by SPDT will lead to diffraction and stray light, which will reduce the reflectivity and image quality of the mirror. This paper studied smoothing polishing based on chemical mechanical polishing to remove turning periodic marks efficiently. Firstly, we studied the chemical corrosion and mechanical removal mechanism of smoothing polishing of the NiP coating through theoretical analysis. Then, the influencing factors of processing the quality of smoothing polishing are analyzed, and the optimal machining parameters and polishing slurry formula are formulated. Finally, through the developed process, the surface roughness of Root Mean Square (RMS) 0.223 nm is realized on the NiP coating, and an ultra-smooth surface that can meet the service accuracy of a hard X-ray mirror is obtained. Our research simplifies the high-precision machining process of the NiP coating and improves the machining efficiency. Therefore, it can be used as a new high-precision manufacturing NiP coating method.

A universal anti-thrombotic and antibacterial coating: A chemical approach directed by Fenton reaction and silane coupling

Blood-contacting devices, including vascular stents, catheters and extracorporeal membrane oxygenation (ECMO), often lead to complications such as thrombosis, inflammation and infections, resulting in implantation failure and adverse events in clinical applications. In this study, a facile and universal antifouling coating with superhydrophobic properties was proposed to improve the contacting interface for combating thrombosis and bacterial infections. The fabrication of the coating was based on Fenton reaction and silane coupling. Oxidative groups were introduced after Fenton activation and topological structure was constructed on the surface by silane coupling agents, and fluoride was used for modification. The obtained superhydrophobic coatings appeared as compact and uniform nanofibers that possessed good resistance to protein adsorption and platelet adhesion, while the thrombus formation was inhibited. In addition, the adhesion of Staphylococcus aureus and Escherichia coli was effectively prevented, which potentially delayed the formation of biofilm and reduced the risk of infections. The coating was applicable to a variety of substrates (polymer, non-metallic inorganic and metallic) and the superhydrophobic properties were preserved after immersion in PBS for 28 days, indicating that it was a promising antithrombotic and antibacterial candidate for modification of medical devices.

Nontarget Approach to Identify Complexing Agents in Atmospheric Aerosol and Rainwater Samples

Atmospheric particles and droplets contain numerous organic substances, some of which form complexes with metal ions, significantly affecting bulk physicochemical properties and chemical reactivity. However, the detection and identification of complexing agents and their corresponding metal complexes remains an analytical challenge. In this study, we developed an LC/HRMS nontarget screening (NTS) approach which allows the selective detection of complexing agents in aerosol particle extracts and rainwater. To achieve this, a T-junction is installed between the LC outlet and the ion source, and a FeCl3 solution is added for postcolumn complexation. The resulting mass spectra are screened for the three characteristic iron(III)-complexes [M - H + FeCl3]-, [M - 2H + FeCl2]-, and [M - 3H + FeCl]- with mass differences (Δm/z) between the complexing agent and the iron complex of 160.8416, 124.8648, and 89.8959, respectively. Up to 29 di- or tricarboxylic acids were identified as complexing agents in aerosol particle samples from two different sites (Melpitz, Germany, and Wangdu, China) at concentrations as low as 50 nM. Thirteen complexing agents were detected even in measurements without postcolumn iron addition from complexation with background Fe3+ traces from the analytical system. At least for the highest concentrated complexing agents, the proposed screening approach can thus be exploited in a NTS approach without any device modification. Besides carboxylic acids, 4-nitrophenol and 4-nitrocatechol were identified as further complexing agents, demonstrating the applicability of the approach to other matrices and to a range of different complexing agents.

Swing arm profilometer as a tool for measuring the shape of large optical surfaces

Swing arm profilometers (SAP) are one of the few options for accurately measuring the shape of large optical surfaces. The data obtained by accurate measurements are essential for the refinement of the manufacturing process and certification of finished products. In this paper, the principle of these devices is described using the example of SAP measuring device supplied to the Joint Laboratory of Optics in Olomouc (JLO) by Zeeko Ltd. Device modifications and new procedures that have simplified the adjustment of the SAP and had a positive impact on the accuracy of the measurements are also presented. Some of these principles and modifications can be applied to other SAP devices, as well. The results of several sample measurements on the SAP device are compared with measurements on Zygo Verifire digital interferometer and Zeiss Contura G2 HTG portal coordinate measuring machine.

Modification of Microfluidic Paper-Based Devices with an Oxidant Layer for Distance Readout of Reducing Substances.

We developed a novel strategy for modification of paper cellulose with water-insoluble oxidants for distance readout of reducing substances on microfluidic paper-based analytical devices (μPADs). Water-insoluble oxidants were formed and modified onto paper cellulose through the redox reaction that occurred between paper cellulose and potassium permanganate deposited on the paper channel, developing a yellowish-brown color on the channel. As aqueous solutions containing reducing substances flowed along the channel, reducing substances were consumed owing to the redox reaction that occurred between oxidants and reducing substances until the reducing substances were depleted, forming a discolored zone on the yellowish-brown channel. The redox reaction between insoluble oxidants and reducing substances on the paper cellulose could be used for distance-based detection of a wide variety of reducing substances, which is similar to the classical potassium permanganate titration that employs the redox reaction that occurred between potassium permanganate and reducing substances. We believe that this method will broaden the analytical applications of distance-based detection on μPADs. This method was applied to ascorbic acid assay and captopril assay in real samples with analytical results comparing well with the labeled values, demonstrating its great potential in real sample analysis.

Organic/polymeric antibiofilm coatings for surface modification of medical devices

Infections arising from implanted medical devices cause considerable challenges for medicinal specialists and patients. These infections usually arise from the accumulation of biofilm on the device, which is difficult to eliminate and typically needs antibiotic treatment and removal of the device. In this regard, efforts have been made to design the devices or functional polymer coatings that have anti-fouling or antimicrobial properties to limit the formation of biofilm and following infection by preventing or killing bacteria near the device surface or by restricting the initial binding of proteins and bacteria. Herein, the extent of device-related infections, the biofilm formation mechanism, the role of biofilm construction in human pathogenesis, and the key strategies for the progress of antibiofilm coatings are discussed. The most promising antibiofilm coating approaches, comprising the surface topography modifications as well as the PEG, hydrogel, polyzwitterion, Benign bacterial biofilm, enzyme, cationic polymer, PTFE, and smart coatings, etc., were also summarized to avoid the biofilm formation and bacteria proliferation via controlling the antibiofilm mechanisms.

Evaluation of the Crystal Structure and Mechanical Properties of Cu Doped TiN Films

In this study, TiN films doped with different copper contents (TiCuN) were prepared by using direct current magnetron sputtering method. The effects of Cu doping on composition, structure, and mechanical properties of TiN films were studied by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), a Vickers microhardnessmeter, and density functional theory (DFT). The results of experimental and DFT study showed that Cu mainly replaced Ti atoms in TiN to form replacement solid solution doping. When Cu replaced Ti in TiN, a weak Cu-N (bond population varied from 0.06 to 0.11) covalent bond formed; meanwhile, the bonding strength of Ti-N (bond population varied from 0.29 to 0.4) bond adjacent to Cu increased. When Cu content was low, a small number of weak Cu-N bonds were formed, with strengthened Ti-N bond near Cu atom, resulting in an increased hardness of Cu doped TiN films. According to the theory of weak bonds, when the Cu content was increased further, the number of weak Cu-N bonds increased and TiCuN hardness decreased. With an increase in Cu content, it was found the toughness of TiCuN also increased. The results of this study will provide a theoretical and experimental guidance for improving the toughness and deformation resistance of TiN, which has a potential application in the surface modification of medical devices.

Functionalized Silicone Elastomer via Alkaline Solution to Coat Phosphorylcholine-Based Copolymer Containing Organosilane to Improve Hemocompatibility for Medical Devices

Surface modification of hemocompatible copolymers on silicone elastomers (SEs) is crucial for the long-term use of medical devices. Both physical adsorption and chemical conjugation are important for modification of SE. Oxygen plasma treatment is widely used to produce silanol groups on SE for silane coupling. However, the plasma reaction is difficult to apply to the surface modification of three-dimensional complex devices. This study demonstrated an appropriate and efficient method with alkaline solution for producing silanol groups on SE for modifying phosphorylcholine-based copolymer with organosilane (cross-MPC copolymer). A 2.5 wt% aqueous solution of potassium hydroxide (KOH) was effective in producing silanol groups and for coating the cross-MPC copolymer. Additionally, we successfully modified the cross-MPC copolymer on the inner surface of SE tubes after pretreatment with the 2.5 wt% KOH aqueous solution, and the copolymer film was coated homogeneously. The cross-MPC copolymer film on SE was stable for one month under fluidic condition with a shear stress of 3.2 Pa. The hollow fiber membrane with the polymer coating inhibited blood coagulation after one week implantation with extracorporeal circulation device using a goat. Therefore, pretreatment of SE using an alkaline solution is an appropriate method for producing silanol groups for coating the cross-MPC copolymer by silane-coupling reaction.

Commentary: Electronic Nicotine Delivery Systems: Seeing Through the Clouds.

Commentary: Electronic Nicotine Delivery Systems: Seeing Through the Clouds.

Application of Transfer Function in Predicting the Temperature Field of Space Equipment Under Periodic External Heat Flow

The temperature state of outer space devices is influenced by the heat flow outside the space. Although traditional numerical simulation analysis methods are highly accurate, they are time-consuming and not conducive for researchers to quickly assess the effects of external heat flow variations and are difficult to apply to program optimization codes that require large-scale iterative calculations or to codes for on-board temperature control chips. This paper presents an analytical algorithm for heat transfer problems: The transfer function method is applied to the thermal control analysis of outer space equipment with a small computational effort and a simple and straightforward computational procedure. Although this analytical approach only considers a limited set of influencing parameters and the precision of the calculation cannot be compared with numerical methods, it can be applied to the early prediction of internal temperature changes caused by heat flow changes outside the modification of outer space devices, embedded in the optimization code of a design solution, or integrated into the code of an on-board temperature control chip with minimum computational effort. In general, the transfer function method is not suitable for solving the radiation term, whereas this paper excludes the radiation term from the time delay calculation based on the small time scale of the radiation term and solves the time delay of the internal temperature relative to the external surface temperature directly, whereas the amplitude decay of the internal temperature change relative to the external surface temperature fluctuation is solved by the steady-state method based on the long period of the external heat flow change. The practicality of the transfer function method in the design of thermal control of external space devices is evidenced by comparing the computational results with those of commercial software and experimental results.

Phytic Acid-Promoted rapid fabrication of natural polypeptide coatings for multifunctional applications

Surface modification or reconstruction of biomaterials, medical devices or other materials hold great promise for improved functionality and applications. However, it is essential to develop coating layers possessing a wide range of functionalities, such as antibacterial, anticorrosive and biocompatible properties. In this work, a simplified method was investigated for the supramolecular assembly of natural bio compounds, phytic acid (PA) and antimicrobial peptide of ε-polylysine (Ply), via one-pot co-deposition. The PA and Ply formed a coating layer on the substrate surface through the inherent surface affinity of PA and ionic bond formation between the electro-positive Ply and electro-negative PA. The co-deposition of PA-Ply is a surface-independent. The physio-chemical features of PA-Ply on titanium (Ti) were characterized to reveal the polymer decoration, surface composition, and microtopography. It was noticed that the PA-Ply coating on Ti (Ti-PA-Ply) could kill greater than 99.9% of both Gram-positive and Gram-negative bacterial pathogens upon their adhesion as compared to that of the pristine Ti surface. Furthermore, the in vivo rat subcutaneous infection model demonstrated effective anti-infection and bactericidal properties of the Ti-PA-Ply surface. In addition, the PA-Ply coating exhibited anti-corrosive property for medical-grade magnesium (Mg) in an electrochemical corrosion model, and promoted the proliferation of endothelial cells. The versatile PA-Ply coating also imparted an improved anti-fogging performance. Thus, the present one-step co-depostition of PA-Ply provided a simple, envirementelly-benign and sustainable approach to the design and fabrication of multi-functional surfaces.