Protective Layer Research Articles

Targeting inerratic deposition behaviour via interface regulation toward dendrite-free zinc metal anodes

Aqueous zinc ion batteries are of interest due to their inherent safety, low cost and high energy density. Nevertheless, critical issues such as uncontrollable dendrite growth, hydrogen evolution reaction and corrosion have dramatically impeded the widespread utilization. To tackle above issues, the versatile artificial protective layer strategy consisting of Zn-friendly, porous and conductive carbon shells is presented for yolk-shell SiO2@void@C (SVC) nanospheres for guiding rapid and homogeneous Zn plating/stripping. On the one hand, the highly zincophilic SiO2 and pore structure interacted significantly with low nucleation overpotential and uniform Zn2+ flux, which favored homogeneous zinc deposition and ionic migration, thereby dramatically aiding in inhibition of Zn dendrites and interruption of interfacial side reactions. On the other hand, SVC nanospheres confer excellent electrical conductivity and mechanical properties, which play an important role in accelerating ion diffusion and boosting structural stability. Consequently, the SVC@Zn electrode exhibits high reversibility and electrochemical stability with a long cycling stability of 1800 h at 5 mA cm−2/1.25 mAh cm−2 and average CE of 99 %. The good properties associated with composition simplicity and abundant yield affords a feasible scheme for high-performance AZIBs.

Study on Thermal Cycling Reliability of Epoxy-Enhanced SAC305 Solder Joint.

In this work, epoxy was added into commercial Sn-3.0Ag-0.5Cu (SAC305) solder paste to enhance the thermal cycling reliability of the joint. The microstructure and fracture surface were observed using a scanning electron microscope/energy dispersive spectrometer (SEM/EDS), and a shear test was performed on the thermally cycled joint samples. The results indicated that during the thermal cycling test, the epoxy protective layer on the surface of the epoxy-enhanced SAC305 solder joint could significantly alleviate the thermal stress caused by coefficients of thermal expansion (CTE) mismatch, resulting in fewer structural defects. The interfacial compound of the original SAC305 solder joints gradually coarsened due to the accelerated atomic diffusion, but epoxy-enhanced SAC305 solder joints demonstrated a thinner interfacial layer and a smaller IMC grain size. Due to the reduced stress concentration and the additional mechanical support provided by the cured epoxy layer, epoxy-enhanced SAC305 solder joints displayed superior shear performance compared to the original joint during the thermal cycling test. After 1000 thermal cycles, Cu-Sn IMC regions were observed on the fracture surfaces of the original SAC305 solder joint, exhibiting brittle fracture characteristics. However, the fracture of the SAC305 solder joint with 8 wt.% epoxy remained within the solder bulk and exhibited a ductile fracture mode. This work indicates that epoxy-enhanced SAC305 solder pastes display high thermal cycling reliability and could meet the design needs of advanced packaging technology for high-performance electronic packaging materials.

Investigation of Oxide Layer Development of X6CrNiNb18-10 Stainless Steel Exposed to High-Temperature Water.

The oxide layer development of X6CrNiNb18-10 (AISI 347) during exposure to high-temperature water has been investigated. Stainless steels are known to form a dual oxide layer in corrosive environments. The secondary Fe-rich oxide layer has no significant protective effect. In contrast, the primary Cr-rich oxide layer is known to reach a stabilized state, protecting the base metal from further oxidation. This study's purpose was to determine the development of oxide layer dimensions over exposure time using SEM, TEM and EDX line scans. While a parabolic development of Cr in the protective primary layer and Fe in the secondary layer was observed, the dimensions of the Ni layer remained constant. Ni required the presence of a pronounced Fe-rich secondary layer before being able to reside on the outer secondary layer. With increasing immersion time, the Ni element fraction surpassed the Cr element fraction in the secondary layer. Oxide growth on the secondary layer could be observed. After 480 h, nearly the entire surface was covered by the outer oxide layer. In the metal matrix, no depletion of Cr or Ni could be observed over time; however, an increased presence of Cr and Ni in the primary layer was found at the expense of Fe content. The Nb-stabilized stainless steel was subject to the formation of Niobium pentoxide (Nb2O5), with the quantity and magnitude of element fraction increasing over exposure time.

Biological Barriers for Drug Delivery and Development of Innovative Therapeutic Approaches in HIV, Pancreatic Cancer, and Hemophilia A/B.

Biological barriers remain a major obstacle for the development of innovative therapeutics. Depending on a disease's pathophysiology, the involved tissues, cell populations, and cellular components, drugs often have to overcome several biological barriers to reach their target cells and become effective in a specific cellular compartment. Human biological barriers are incredibly diverse and include multiple layers of protection and obstruction. Importantly, biological barriers are not only found at the organ/tissue level, but also include cellular structures such as the outer plasma membrane, the endolysosomal machinery, and the nuclear envelope. Nowadays, clinicians have access to a broad arsenal of therapeutics ranging from chemically synthesized small molecules, biologicals including recombinant proteins (such as monoclonal antibodies and hormones), nucleic-acid-based therapeutics, and antibody-drug conjugates (ADCs), to modern viral-vector-mediated gene therapy. In the past decade, the therapeutic landscape has been changing rapidly, giving rise to a multitude of innovative therapy approaches. In 2018, the FDA approval of patisiran paved the way for small interfering RNAs (siRNAs) to become a novel class of nucleic-acid-based therapeutics, which-upon effective drug delivery to their target cells-allow to elegantly regulate the post-transcriptional gene expression. The recent approvals of valoctocogene roxaparvovec and etranacogene dezaparvovec for the treatment of hemophilia A and B, respectively, mark the breakthrough of viral-vector-based gene therapy as a new tool to cure disease. A multitude of highly innovative medicines and drug delivery methods including mRNA-based cancer vaccines and exosome-targeted therapy is on the verge of entering the market and changing the treatment landscape for a broad range of conditions. In this review, we provide insights into three different disease entities, which are clinically, scientifically, and socioeconomically impactful and have given rise to many technological advancements: acquired immunodeficiency syndrome (AIDS) as a predominant infectious disease, pancreatic carcinoma as one of the most lethal solid cancers, and hemophilia A/B as a hereditary genetic disorder. Our primary objective is to highlight the overarching principles of biological barriers that can be identified across different disease areas. Our second goal is to showcase which therapeutic approaches designed to cross disease-specific biological barriers have been promising in effectively treating disease. In this context, we will exemplify how the right selection of the drug category and delivery vehicle, mode of administration, and therapeutic target(s) can help overcome various biological barriers to prevent, treat, and cure disease.

What can naked mole-rats teach us about ameliorating hypoxia-related human diseases?

Ameliorating the deleterious impact of systemic or tissue-level hypoxia or ischemia is key to preventing or treating many human diseases and pathologies. Usefully, environmental hypoxia is also a common challenge in many natural habitats; animals that are native to such hypoxic niches often exhibit strategies that enable them to thrive with limited O2 availability. Studying how such species have evolved to tolerate systemic hypoxia offers a promising avenue of discovery for novel strategies to mitigate the deleterious effects of hypoxia in human diseases and pathologies. Of particular interest are naked mole-rats, which are among the most hypoxia-tolerant mammals. Naked mole-rats that tolerate severe hypoxia in a laboratory setting are also protected against clinically relevant mimics of heart attack and stroke. The mechanisms that support this tolerance are currently being elucidated but results to date suggest that metabolic rate suppression, reprogramming of metabolic pathways, and mechanisms that defend against deleterious perturbations of cellular signaling pathways all provide layers of protection. Herein, we synthesize and discuss what is known regarding adaptations to hypoxia in the naked mole-rat cardiopulmonary system and brain, as these systems comprise both the primary means of delivering O2 to tissues and the most hypoxia-sensitive organs in mammals.

Ostwald-Ripening Induced Interfacial Protection Layer Boosts 1,000,000-Cycled Hydronium-Ion Battery.

Collapsing and degradation of active materials caused by the electrode/electrolyte interface instability in aqueous batteries are one of the main obstacles that mitigate the capacity. Herein by reversing the notorious side reactions include the loss and dissolution of electrode materials: as we applied Ostwald ripening (OR) in the electrochemical cycling of a copper hexacyanoferrate electrode in a hydronium-ion batteries, the dissolved Cu and Fe ions undergo a crystallization process that creates a stable interface layer of cross-linked cubes on the electrode surface. The layer exposed the low-index crystal planes (100) and (110) through OR-induced electrode particle growth, supplemented by vacancy-ordered (100) superlattices that facilitated ion migration. Our design stabilized the electrode-electrolyte interface considerably, achieving a cycle life of one million cycles with capacity retention of 91.6%, and a capacity retention of 91.7% after 3000 cycles for a full battery.

Facilitating superior electrochemical efficacy and ultra rapid kinetic in Co/Ni-free layered oxides for sodium-ion batteries with phosphate-growing layer fast ion conductors

Co/Ni-free layered oxides have garnered significant interest due to their environmental friendliness and facile synthesis methodologies, while facing major challenges of inferior cycling stability and rate capability. Addressing these drawbacks necessitates the enhancement of the surface properties of Co/Ni-free layered oxides. This work introduces a Co/Ni-free layered oxide, Na0.67Mn0.65Fe0.3Al0.05O2 (NMFA), which has been subjected to phosphate-based surface engineering. This targeted surface modification aims to augment the specific surface area and establish a protective layer on NMFA. Such improvements are critical for expanding the effective electrochemical reaction zone, broadening sodium ion diffusion pathways, curtailing the P2-OP4 phase transition, and reducing the activation energy for interfacial charge transfer. This multifaceted surface treatment epitomizes the ingenious design and realization of advanced Co/Ni-free layered oxide cathode materials through straightforward processing techniques. Notably, the NMFA subjected to 3%-AlPO4 surface modification demonstrated an initial discharge capacity of 189.1 mAh/g at 0.1C, maintaining its capacity after 500 cycles at 10C. Additionally, DFT calculations corroborate that such surface growth can bolster electrical conductivity, restrain oxygen liberation and foster sodium ion migration. This elucidates that the phosphate growth layer serves as the oxygen reservoir. Accordingly, this investigation propounds a promising avenue to circumvent the challenges confronting Co/Ni-free layered oxides, thus paving the way for the development of high-performance cathode materials.

Corrosion potential and theoretical studies of fabricated Schiff base for carbidic austempered ductile iron in 1M H2SO4 solution

In this body of work, a chemical known as 2-cyano-N-(4-morpholino benzyl dine) acetohydrazide (CMBAH) is explored for its ability to suppress the carbidic austempered ductile iron (CADI) corrosion in 1M H2SO4. Density functional theory was used in experiments and theoretical investigations to investigate the inhibiting impact. The corrosion of CADI alloys in 1M H2SO4 produced a corrosion resistance superior to that of CADI heat treatment (H.T.). As-cast carbidic ductile iron (CDI) 4 alloy with 1.5%t Cr-Nb has a corrosion rate (C.R.) of 11.69 mm/year, which drops to 5.31 mm/year at HT-275 °C and 6.13 mm/year at HT-375 °C. When describing the adsorption of inhibitors, the Langmuir adsorption isotherm is the most effective method. The findings of the Gads show that the inhibition was induced mainly by the physisorption on the surface CADI alloys. In addition to this, it was found that the results of the experiments and the hypotheses were largely harmonious with one another. The formation of protective layers on the CADI surfaces is also visible in the images captured by the SEM. In 1M H2SO4, these Schiff base inhibitors effectively prevent corrosion caused by CADI. However, the combination of inhibitors leads to a fine microstructure with ausferrite and narrow ferrite needles, promoting corrosion resistance. The CADI needles rated an upper ausferritic microstructure with wide ferrite needles.

Gossypol derivate as a green anti-corrosion agent in the aqueous phase of crude oil.

Keeping recruitment of green and cost-effective solutions for environmental challenges in view, the current work was designed to solve the problems related to metal corrosion in the aqueous phases of crude oil in chemical industries. Green materials can play an important role in protecting metals from this corrosion. Hence, the green anti-corrosion material based upon gossypol derivate is suggested to solve the above problems. The electrochemical characteristics were appraised by cyclic voltammetry, electrochemical impedance spectroscopy, potentiodynamic polarization, and electrochemical noise methods. The thermodynamics were studied by gravimetric analyses. The surface morphology was scrutinized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Density functional theory and molecular dynamic simulations were exploited in theoretical analyses. The gossypol derivate is green, non-toxic, more efficient, non-volatile, and chemically stable anti-corrosion material for gas and oil industries. Carbon steel corrosion simulated in aqueous phases of crude oil (NaCl solutions (1.0M) saturated with H2S and CO2) was maximally prohibited by forming a protective layer of binaphthalene. Its protection degree is 96.71% (at 100.0mg/L/0.107mM). The gossypol ring is a suitable core for preparing the next modification materials to protect against corrosion. The rigid adsorption progressed mainly via hydroxyl functional moieties. Compared to the inhibition behavior of the neutral form of gossypol, the optimized protonated form causes a greater inhibition.

Ostwald‐Ripening Induced Interfacial Protection Layer Boosts 1,000,000‐Cycled Hydronium‐Ion Battery

Collapsing and degradation of active materials caused by the electrode/electrolyte interface instability in aqueous batteries are one of the main obstacles that mitigate the capacity. Herein by reversing the notorious side reactions include the loss and dissolution of electrode materials: as we applied Ostwald ripening (OR) in the electrochemical cycling of a copper hexacyanoferrate electrode in a hydronium‐ion batteries, the dissolved Cu and Fe ions undergo a crystallization process that creates a stable interface layer of cross‐linked cubes on the electrode surface. The layer exposed the low‐index crystal planes (100) and (110) through OR‐induced electrode particle growth, supplemented by vacancy‐ordered (100) superlattices that facilitated ion migration. Our design stabilized the electrode–electrolyte interface considerably, achieving a cycle life of one million cycles with capacity retention of 91.6%, and a capacity retention of 91.7% after 3000 cycles for a full battery.

Characterizing Referrals to Professional Health Monitoring Programs for Unprofessional Sexual Behavior.

Concerns about sexual misconduct by health care professionals have been highlighted by recent high-profile cases. Professional health monitoring programs (PHPs) offer an additional layer of protection when health care professionals with a history of unprofessional sexual behavior (USB) return to practice; however, little is known about the characteristics or outcomes of clinicians referred to a PHP because of USB. Data were extracted from over 35 years of PHP records involving USB-related referrals (N = 570). The majority of cases were deemed ineligible for PHP monitoring and handled by other entities (e.g., licensing board, legal system). Of the 232 monitored cases (46.84 ± 9.42 years; 95.7% male), most were physicians (n = 156, 67.2%), with 75.9 percent of monitored cases involving USB with at least one patient. Most (74.9%) PHP monitoring outcomes were classified as "successful" or "very successful." Only three individuals (1.3%) who completed their monitoring were rereferred to the PHP. Monitored professionals exhibited less severe USB and were less likely to experience legal or disciplinary consequences (57.3% versus 69.8%, Cramer's V = .174, p < .0001) compared with unmonitored professionals. Findings enhance transparency of the PHP process and highlight its utility in safely returning clinicians to practice. Results may inform policies to prevent USB by health care professionals.

Revealing the environmental-assisted degeneration mechanism of an Al-containing dual-phase high entropy alloy in supercritical water

A dual-phase high entropy alloy (DP-HEA) containing 7.82 wt% Al was synthesized to withstand corrosive supercritical water. The long-term corrosion and quasi-static tensile tests reveal superior resistance to such environmental-assisted degeneration. The outstanding corrosion resistance can be attributed to the high aluminum content in B2 phase, which forms a continuous Al2O3 layer for protection, while the FCC phase is selectively corroded. Under external stress, stress corrosion cracking (SCC) initiates from surface oxide and penetrates uncompact mixed Cr/Al-rich oxide in deteriorated FCC regions or corroded phase interface, though network-shaped B2 can inhibit SCC propagation, which supports the brittle film rupture model.

Assessing the durability of diverse leather tanning techniques for the manufacturing of leather goods through artificial aging processes

In the context of the growing demand for sustainable consumption, especially in the fashion industry, leather remains an intriguing material. Its durability and quality not only ensure the longevity of products but also support the rise of practices like second-hand use and upcycling. This study evaluates the longevity of tanning alternatives - triazine-based and a combination of synthetic and vegetable tannins - compared to the widely used chrome tanning. Artificial aging processes, incorporating heat, humidity, UV exposure, and microbial conditions, were applied to leathers tanned with the three methods. Physico-mechanical measurements, commonly specified in industrial standards, were conducted alongside chemical analyses to evaluate potential degradations associated with chrome tanning as the reference. The aging processes impacted leather performances, but finished leathers remained suitable for applications. Indeed, results on finished leathers indicated minimal degradation after aging, emphasizing the importance of the protective layer for longevity. Considerations include adapting finishing to surface structures and addressing potential stiffness in triazine-tanned leather, necessitating further exploration.

Synthesis of High-Performance Colorless Polyimides with Asymmetric Diamine: Application in Flexible Electronic Devices.

Colorless polyimides (CPIs) are widely used as high-performance materials in flexible electronic devices. From a molecular design standpoint, the industry continues to encounter challenges in developing CPIs with desired attributes, including exceptional optical transparency, excellent thermal stability, and enhanced mechanical strength. This study presents and validates a method for controlling 2-substituents, with a specific emphasis on examining how these substituents affect the thermal, mechanical, optical, and dielectric characteristics of CPIs. The presence of two CF3 groups on the same side of the diamine structure ensured the transmittance of the film. The charge transfer effect and the molecular distance are dynamically regulated by changing the 2-substituent (-OCH3/-CH3/H/F). The polyimide exhibited a well-maintained equilibrium between transparency and thermal stability, with a T500nm value ranging from 86.2 to 89.6% in the visible region, and a glass transition temperature (Tg) ranging from 358.6 to 376.0 °C. Additionally, the 6FDA-2-MTFMB compound, when combined with methyl, excels as a protective layer and base material, exhibiting excellent performance in various aspects. It has been verified as an appropriate option for flexible photodetectors and wearable piezoresistive sensors. In summary, this systematic investigation will provide a comprehensive and demonstrative methodology for developing CPIs that are capable of adapting to flexible electronic devices.

Wet oxidation behavior of Al-Y synergistic modified liquid phase sintered SiC

The wet oxidation behavior of LPS-SiC ceramics as well as the synergistic modification effect of Al2O3 and Y2O3 as sintering aids are investigated. The results show that SiO2 oxide scale is transformed to aluminosilicate with the addition of Al2O3, which can inhibit the crystallization of oxide layer and formation of cracks. The aluminosilicate oxide layers have low kl value close to zero, which can reduce the consumption of protective oxide layer under water-containing atmosphere. Y2O3 are mainly transformed to Y2Si2O7 to resist the diffusion of oxidative gas. However, with the increase of sintering aids content, the aluminosilicate layer with excessive viscosity limits the emission of gas generated by oxidation and causes many bubbles left in oxide scale which provided rapid channel for oxidative gas. Therefore, LPS-SiC with lower content of sintering aids has better oxidation resistance. This work can provide guidance for the component design of SiC-based ceramics and composites.

Repair of ordinary concrete using basalt fiber reinforced geopolymer: High temperature resistance and micro structure evolution of adhesive interface

Good bonding properties in the interfacial transition zone (ITZ) between the substrate and the repair material are critical to the success of the repair, and a good repair material can act as a protective layer to reduce the impact of fire on the structure. In this paper, Ordinary concrete (OP), geopolymer mortar (GP), and basalt fiber reinforced geopolymer mortar (GPb) were poured as the three repair materials on the roughened surface of the old substrate. The bonded specimens were exposed to temperatures of 23 °C, 200 °C, 400 °C, 600 °C and 800 °C for 1 h. The interfacial bond strength of the bonded specimens was tested by slant shear test, and the physical phase change of the repair material and the microstructure of the ITZ were analyzed by microscopic test. The results showed that the mechanical properties and high temperature resistance of ITZ were best when the old substrate interfaces were grinded and grooved and GPb was used as the repair material. Compared with S-OP, the bond strength of S-GPb was 26.92 %, 27.43 %, 46.50 %, 44.26 %, and 97.02 % higher at different temperatures. The increase in interfacial bond strength can be attributed to three mechanisms: (1) Mechanical interlocking with the old substrate with a rough surface. (2) The increase in temperature accelerates the volcanic ash reaction, and the formation of hydration products further fills the voids at the ITZ, maintaining the strength and compactness of the ITZ. (3) The addition of basalt fibers can form an anchoring effect at the interface, reducing the risk of interfacial spalling and cracking caused by material shrinkage in the ITZ.

Dendrite-free zinc metal anode for long-life zinc-ion batteries enabled by an artificial hydrophobic-zincophilic coating

Considering the desired energy density, safety and cost-effectiveness, rechargeable zinc-ion batteries (ZIBs) are regarded as one of the most promising energy storage units in next-generation energy systems. Nonetheless, the service life of the current ZIBs is significantly limited by rampant dendrite growth and severe parasitic reactions occurring on the anode side. To overcome these issues caused by poor interfacial ionic conduction and water erosion, we have developed a facile strategy to fabricate a uniform zinc borate layer at the zinc anode/electrolyte interface (ZnBO). Such protective layer integrates superhydrophobic-zincopholic properties, which can effectively eliminate the direct contact of water molecules on the anode, and homogenize the interfacial ionic transfer, thereby enhancing the cyclic stability of the zinc plating/stripping. As a result, the as-prepared ZnBO-coated anode exhibits extended lifespan of 1200 h at 1 mA cm−2 and demonstrates remarkable durability of 570 h at 20 mA cm−2 in Zn||Zn symmetric cells. Additionally, when coupled to an NH4V4O10 (NVO) cathode, it also delivers a superior cyclability (203.5 mAh/g after 2000 cycles at 5 A/g, 89.3 % capacity retention) in coin full cells and a feasible capacity of 2.5 mAh at 1 A/g after 200 cycles in pouch full cells. This work offers a unique perspective on integrating hydrophobicity and zincophilicity at the anode/electrolyte interface through an artificial layer, thereby enhancing the cycle lifespan of ZIBs.

Noninvasive Multitechnique Analysis of Baroque Amber Artworks From Gdansk: The Benefits of Using Raman Spectroscopy

ABSTRACTThe multidisciplinary, noninvasive analysis of baroque amber artworks is part of a research project that deals with the most valuable objects from the Museum of Gdansk (Poland). The two most interesting objects will be presented here: a Baroque Gdansk wardrobe‐shaped amber cabinet (made by Johann Georg Zernebach, Gdansk, 1724) and a crucifix (Gdansk, 17th century). Macro‐ (UV, IR, and X‐radiography) and micro‐ (XRF and Raman spectroscopy) analytical methods were applied to reveal traces of old conservation treatments and uncover the techniques of the 17th and 18th century amber masters. UV photography shows the differences between the amber plates that are not so easily detected under visible light, while XRF spectrometry detects elements atypical for amber objects, suggesting previous conservation treatments. Confocal Raman measurements, especially Raman depth profiling, were performed for the amber artworks and allowed to detect areas of previous conservation treatments. Single‐point scans were collected from the surface (0 μm) to a depth of −200 μm, with a step of 50 μm. The results allowed us to identify three different types of zones: where the amber was preserved without any protective layer, places where the amber was covered with a thin layer of a protective substance, and places where amber elements were compensated for loss using a binding agent and filler. The presented project allowed the development of a comprehensive methodology for the analysis of amber objects, especially to optimize the capabilities of confocal Raman microscopy. The combination of macro‐ and microanalytical techniques made it possible to obtain a broad overview of such complex artworks while optimizing the time and effort spent on the investigations.

“I feel like it's just really become second nature, almost like the screen’s not there”: a qualitative case study of the transition to telehealth for home visitation program to support fragile infants due to the COVID-19 pandemic

A subset of early childhood home visitation programs support fragile infants and prevent hospital readmission as infants transition out of the neonatal intensive care unit (NICU) into their home. However, the COVID-19 pandemic initiated an unexpected change in the delivery of home visitation care to adhere to social distancing guidelines, resulting in a rapid transition into telehealth services. In this study, individual semi-structured interviews were conducted with staff from a NICU-transition home visitation program in Arizona. The Modified Technology Acceptance Model (MTAM) was used to evaluate the experiences of in-person to telehealth home visitations during the COVID-19 pandemic. Rapid Qualitative Analysis Method was utilized to generate a thematic analysis. Three major themes were identified: staff-centric, family-centric, and the experience of collective adjustment to the stressors of the pandemic. Participants faced challenges transitioning to telehealth visits, including not being able to physically demonstrate development skills on the infant. However, the telehealth model allowed staff to serve a larger geographic area, as well as allowing them to build a larger caseload as they had more control over their schedule. Staff also noted that families appreciated telehealth home visits as an added layer of health protection for their fragile infants. Because the transition to telehealth was abruptly necessitated by the COVID-19 pandemic, the study participants did not have the option to not use telehealth; thus, in the future, the MTAM framework could benefit from adaptions that address the rapid adoption of technology due to large disruptors such as COVID-19.

Eco-friendly modified chitosan as corrosion inhibitor for carbon steel in acidic medium: Experimental and in-depth theoretical approaches

The industrial and medical sectors have a great interest in chitosan due to its unique properties, such as abundance, renewability, non-toxicity, antibacterial activity, biodegradability, and polyfunctionality. In this work, two modified chitosan Schiff bases (ChSB-1 and ChSB-2) were made using condensation methods, and their potential as corrosion inhibitor for carbon steel in 1 M HCl was investigated using chemical and electrochemical techniques. The ChSB-1 and ChSB-2 inhibitors exhibited remarkable inhibitory performance, as evidenced by the mass loss data, which showed 89.3 % and 91.5 % efficacy at 1 mM concentration, respectively. Because of the electron-donor substituent of methoxy (–OCH3), ChSB-2's active sites have more delocalized electrons than ChSB-1's. The PDP results showed that both ChSB-1 and ChSB-2 inhibitors have anti-corrosion characteristics because heteroatoms caused a protective layer to develop that functioned as mixed-typed inhibitors. The calculated adsorption-free energy ∆Gadso for ChSB-1 and ChSB-2, respectively, was found −36.1 and − 37.1 kJ mol−1. The ChSB-1 and ChSB-2 inhibitors adsorb on carbon steel in acidic conditions through physisorption and chemisorption interactions, and their adsorption is in line with the Langmuir adsorption model. Inhibited and uninhibited metallic surfaces were subjected to surface morphological assessments using contact angle (CA), the scanning electron microscopy and the energy dispersive X-ray (SEM/EDX) analysis. The DMol3 part of Materials Studio 7.0 software was used to perform the quantum chemical calculations based on DFT to visualize the structural features. Studies from quantum chemistry suggest the possibility of surface interaction between the unoccupied orbitals of the metal surface and the inhibitors ChSB-1, ChSB-2, ChSB-1H+, and ChSB-2H+. The results clearly show that the two inhibitors work well as environmentally friendly carbon steel corrosion inhibitors in acidic medium. This could be advantageous for industrial procedures such as pickling, cleaning, acidizing oil drilling in oil wells, and using citrus to de-sediment boilers.