Transfer Length Research Articles

Selective chemical doping of carbon nanotube conductors to reduce contact resistance with copper in ultrasonic welds

Electrochemical devices such as batteries, fuel cells, and capacitors employing a carbon nanotube (CNT) electrode can be improved by lowering the contact resistance between CNTs and metallic contacts. The current work investigates two simultaneous strategies to enhance the contact by using chemical doping of CNTs with potassium tetrabromoaurate (KAuBr4) and ultrasonic welding to a metal foil. The specific contact resistivity was measured using the transfer length method (TLM) to evaluate CNT test structures having ultrasonically welded Cu contacts with and without KAuBr4 doping. Purified CNT-Cu samples had a specific contact resistivity of 5.4 mΩ cm2, whereas the KAuBr4 doped CNT-Cu samples were 2.2 mΩ cm2. Confirmation of selective doping to the weld region was made using measured differences in the emissivity of purified and KAuBr4 doped CNTs, which were 0.84 and 0.56, respectively. The lower contact resistance from KAuBr4 doped CNT-Cu ultrasonic welds also reduced the extent of Joule heating beyond the contact region when applying increasing current to failure in a 2-terminal test structure. The benefit of selectively doped CNT-Cu welds was demonstrated across rectangular ribbon and electrode form factors up to an area of 6 cm × 8 cm (typical of electrochemical pouch-cell current collectors). Each form factor showed a 1.5× reduction in peak temperature when selective doping of the CNTs was performed prior to ultrasonic welding of the Cu contact. Thus, the combination of selective doping and ultrasonic welding demonstrates a viable method to fabricate low electrical resistance between CNT electrodes and metallic contacts for electrochemical devices.

Effect of fabrication process on contact resistance and channel in graphene field effect transistors

Contact resistance, as one of the main parameters that limits the performance of graphene-based transistors, is highly dependent on the metal-graphene contact fabrication processes. These processes are investigated and the corresponding resistances are measured based on the transfer length method (TLM). In fabrication processes, when annealing is done on chemical vapor deposition (CVD)-grown graphene samples that are transferred onto SiO2/Si substrates, the adhesion of graphene to the substrate is improved, and poly methyl methacrylate (PMMA) residues are also reduced. When the metal deposition layer is first applied to the graphene, and then, the photolithography process is performed to define the electrodes and graphene sheet, the graphene-metal contact resistance is better than that in other methods due to the removal of photoresist residues. In fact, by changing the sequence of the fabrication process steps, the direct contact between photoresist and graphene surface can be prevented. Thus, the contact resistance is reduced and conductivity increases, and in this way, the performance of graphene transistor improves. The results show that the fabrication process has a noticeable effect on the transistor properties such as contact resistance, channel sheet resistance, and conductivity.‌ Here, by using the annealing process and changing the order of photolithography processes, a contact resistance of 470 Ω μm is obtained for Ni-graphene contact, which is relatively favorable.

Stewardship Prompts to Improve Antibiotic Selection for Urinary Tract Infection

Urinary tract infection (UTI) is the second most common infection leading to hospitalization and is often associated with gram-negative multidrug-resistant organisms (MDROs). Clinicians overuse extended-spectrum antibiotics although most patients are at low risk for MDRO infection. Safe strategies to limit overuse of empiric antibiotics are needed. To evaluate whether computerized provider order entry (CPOE) prompts providing patient- and pathogen-specific MDRO risk estimates could reduce use of empiric extended-spectrum antibiotics for treatment of UTI. Cluster-randomized trial in 59 US community hospitals comparing the effect of a CPOE stewardship bundle (education, feedback, and real-time and risk-based CPOE prompts; 29 hospitals) vs routine stewardship (n = 30 hospitals) on antibiotic selection during the first 3 hospital days (empiric period) in noncritically ill adults (≥18 years) hospitalized with UTI with an 18-month baseline (April 1, 2017-September 30, 2018) and 15-month intervention period (April 1, 2019-June 30, 2020). CPOE prompts recommending empiric standard-spectrum antibiotics in patients ordered to receive extended-spectrum antibiotics who have low estimated absolute risk (<10%) of MDRO UTI, coupled with feedback and education. The primary outcome was empiric (first 3 days of hospitalization) extended-spectrum antibiotic days of therapy. Secondary outcomes included empiric vancomycin and antipseudomonal days of therapy. Safety outcomes included days to intensive care unit (ICU) transfer and hospital length of stay. Outcomes were assessed using generalized linear mixed-effect models to assess differences between the baseline and intervention periods. Among 127 403 adult patients (71 991 baseline and 55 412 intervention period) admitted with UTI in 59 hospitals, the mean (SD) age was 69.4 (17.9) years, 30.5% were male, and the median Elixhauser Comorbidity Index count was 4 (IQR, 2-5). Compared with routine stewardship, the group using CPOE prompts had a 17.4% (95% CI, 11.2%-23.2%) reduction in empiric extended-spectrum days of therapy (rate ratio, 0.83 [95% CI, 0.77-0.89]; P < .001). The safety outcomes of mean days to ICU transfer (6.6 vs 7.0 days) and hospital length of stay (6.3 vs 6.5 days) did not differ significantly between the routine and intervention groups, respectively. Compared with routine stewardship, CPOE prompts providing real-time recommendations for standard-spectrum antibiotics for patients with low MDRO risk coupled with feedback and education significantly reduced empiric extended-spectrum antibiotic use among noncritically ill adults admitted with UTI without changing hospital length of stay or days to ICU transfers. ClinicalTrials.gov Identifier: NCT03697096.

Stewardship Prompts to Improve Antibiotic Selection for Pneumonia

Pneumonia is the most common infection requiring hospitalization and is a major reason for overuse of extended-spectrum antibiotics. Despite low risk of multidrug-resistant organism (MDRO) infection, clinical uncertainty often drives initial antibiotic selection. Strategies to limit empiric antibiotic overuse for patients with pneumonia are needed. To evaluate whether computerized provider order entry (CPOE) prompts providing patient- and pathogen-specific MDRO infection risk estimates could reduce empiric extended-spectrum antibiotics for non-critically ill patients admitted with pneumonia. Cluster-randomized trial in 59 US community hospitals comparing the effect of a CPOE stewardship bundle (education, feedback, and real-time MDRO risk-based CPOE prompts; n = 29 hospitals) vs routine stewardship (n = 30 hospitals) on antibiotic selection during the first 3 hospital days (empiric period) in non-critically ill adults (≥18 years) hospitalized with pneumonia. There was an 18-month baseline period from April 1, 2017, to September 30, 2018, and a 15-month intervention period from April 1, 2019, to June 30, 2020. CPOE prompts recommending standard-spectrum antibiotics in patients ordered to receive extended-spectrum antibiotics during the empiric period who have low estimated absolute risk (<10%) of MDRO pneumonia, coupled with feedback and education. The primary outcome was empiric (first 3 days of hospitalization) extended-spectrum antibiotic days of therapy. Secondary outcomes included empiric vancomycin and antipseudomonal days of therapy and safety outcomes included days to intensive care unit (ICU) transfer and hospital length of stay. Outcomes compared differences between baseline and intervention periods across strategies. Among 59 hospitals with 96 451 (51 671 in the baseline period and 44 780 in the intervention period) adult patients admitted with pneumonia, the mean (SD) age of patients was 68.1 (17.0) years, 48.1% were men, and the median (IQR) Elixhauser comorbidity count was 4 (2-6). Compared with routine stewardship, the group using CPOE prompts had a 28.4% reduction in empiric extended-spectrum days of therapy (rate ratio, 0.72 [95% CI, 0.66-0.78]; P < .001). Safety outcomes of mean days to ICU transfer (6.5 vs 7.1 days) and hospital length of stay (6.8 vs 7.1 days) did not differ significantly between the routine and CPOE intervention groups. Empiric extended-spectrum antibiotic use was significantly lower among adults admitted with pneumonia to non-ICU settings in hospitals using education, feedback, and CPOE prompts recommending standard-spectrum antibiotics for patients at low risk of MDRO infection, compared with routine stewardship practices. Hospital length of stay and days to ICU transfer were unchanged. ClinicalTrials.gov Identifier: NCT03697070.

Analysis of metal and zinc oxide semiconductor interface resistance using transmission line method

The transmission line method (TLM) is modified to analyze the contact resistance between the metal and zinc oxide semiconductor considering interface resistance. TCAD is used to simulate an ideal defect-less state and compare it with experimental result. It is found that the current transfer length can be overestimated in conventional TLM measurement. The importance of interface resistance is shown through interface trap and Schottky contact effect analysis: Resistance comparison between different metal used device, and the activation energy shift measurement after O2 pre-annealing. Based on these, the conventional resistance equation for TLM is corrected by separating channel resistance and non-ideal contact resistance. The mobility and temperature coefficient of resistance (TCR) of ZnO channel are extracted using the suggested method. This shows the importance of metal/semiconductor interface resistance in devices using semiconductor channel.

Modelling reaction transfer velocities in disconnected compact heterogeneous multilayer reactive material systems

The tuning of the self-propagating reaction is studied theoretically by introducing a non-reactive material between two reactive material elements. For the study, the Ni/Al bilayer system was chosen. The Ni/Al elements were placed on a silicon wafer covered with a 1-µm-thick silicon dioxide. The spaces between the multilayer reactive material elements were filled with different non-reactive materials covering a wide range of thermal properties. On top of this heterogeneous layer, a 1-µm-thick sealing layer was placed consisting of the filler material. The carried out two-dimensional simulations demonstrated that embedding material allows to scale the ignition transfer time and the heat propagation velocity. For example, for a transfer length of 1 µm, the ignition time can be tuned from nano- to microseconds. Consequently, in contrast to previous results embedding materials allow scaling the properties of the self-propagating reaction in heterogeneous reactive material systems.Graphical abstract

Innovating in-situ characterization: a comprehensive measurement system for measuring the ZT and the contact resistance of vertical thermolegs exploiting the vertical transfer length method

In order to optimize their system design and manufacturing processes, it is crucial to undertake a thorough electrical and thermal characterization of micro thermoelectric generators (µTEGs). To address this need, a highly advanced and fully integrated in-situ measurement system has been developed. The main objectives of this system are to (1) enable the measurement of ZT and thereby of all thermoelectric (TE) properties of thermolegs made from powder-based TE materials and (2) at the same time accurately measure the contact resistance between the TE material and the electrical contacts. The µTEG fabrication concept used in this study is based on copper-cladded printed circuit board (PCB) material as a substrate, using the Cu layers for easy contact formation. In a first step, an innovative measurement concept, based on a distinctive vertical rendition of the well-established transfer length method, has been realized, allowing for the in-situ measurement of contact resistance between the TE material and the copper conductors on the PCB substrate. This enables a comprehensive assessment of the impact exerted by the applied force and temperature during e.g. a hot-pressing step for compacting the powder-based thermolegs during the manufacturing process. In a second step, a comprehensive measurement platform, referred to as the ZT-Card, has been devised to facilitate the evaluation of all relevant TE material properties—Seebeck voltage, electrical conductivity and thermal conductivity (all measured in vertical cross-plane orientation)—inherent to a highly miniaturized thermoleg. Additionally, the ZT-Card also allows for the assessment of contact resistance between the copper contacts and the TE material. Successful testing of this measurement system inspires confidence in the capabilities of the platform and will aid in future µTEG development.

Bending performance of wet joints in negative moment zone of prefabricated small-box girder bridges: Experimental and numerical study

The prefabricated small-box girder (PSBG) structure adopts the construction method of simple supporting beam transforming to continuous beam, which results in negative bending moment on the box girder supports and large tensile stress on the top of the longitudinal wet joints. Due to the relatively low tensile strength of concrete, the top plate of the bridge in the negative bending moment zone is susceptible to cracking under the load of vehicles, as well as due to the shrinkage and creep of concrete. This poses a risk to the safety, applicability, and durability of the bridge structure and may lead to a reduction in these aspects. Ultra-high performance concrete (UHPC) has excellent tensile performance and stronger crack control capability, which can effectively improve the anti-cracking and durability of the wet joints of the PSBG. In the present study, the research focused on the negative bending moment zone of a three-span continuous small–box girder bridges. This zone was selected as the research object and served as the basis for designing a stepped wet joint girder, where UHPC is partially cast on the top plate. By conducting three-point bending tests, we compared the bending mechanical properties of the joint girders when poured with normal concrete (NC) and UHPC in the joint top area. Further, the key factors affecting the anti-cracking performance and bearing capacity, including the length and thickness of the UHPC layer and the width of the wet joint, were analyzed by finite element simulation. The results show that the contribution of the top plate UHPC to tensile stress cannot be ignored. Compared with the NC joint girder, the UHPC joint girder has better toughness and plasticity, and the cracking load and bearing capacity increased by 28.6% and 9.7%, respectively. According to the simulation results, as the increase of the length and thickness of the UHPC layer and the width of wet joint, the anti-cracking and bearing capacities of the PSBG with the wet joint were enhanced. The thickness and length of the UHPC layer had a significant effect on improving the anti-cracking performance of the wet joint, and the joint width only needed to meet the transfer length of rebar bond stress.

Numerical study of transient supercooling performance and thermal stress analysis of segmented annular thermoelectric cooler

A multiphysics-coupled numerical simulation of a segmental annular thermoelectric cooler (SATEC) was performed using a three-dimensional finite element method. A coupling model of the temperature, stress, and electric fields was established based on the three-dimensional transient states. Moreover, the effects of different pulse width (τ), pulse current amplitude (Pa), pulse current shape parameter (m), heat transfer coefficient (h), angle (θ), and length (H) of the thermoelectric leg on the SATEC transient properties and von Mises stress were studied. The results show that τ and Pa are the key influencing factors of SATEC. The larger the h, the more optimized the heat transfer effect of the SATEC hot end. However, when h increased to a certain value, the changes in the transient performance were insignificant. The optimal pulse can be achieved when the input pulse current Iop = 6.47 A and pulse width τ = 20 s. When the length of the thermoelectric leg H4 was 3 mm and the thermoelectric leg angle θ2 was 7°, the performance of SATEC was optimal, with Tc,min being 249.57 K, Tc,max being 279.50 K, thold being 5.5 s, and the maximum von Mises stress being 37.48 MPa. The results show that different supercooling indices and von Mises stresses could be obtained for different pulse current shapes. Geometric optimization of SATEC can improve the cooling performance and reduce the von Mises stress, thereby providing a theoretical reference for practical engineering applications and thermoelectric cooling research.

Quantification of the sheet resistance between two-dimensional semiconductors and semi-metals by a contact-end-resistance method

Semi-metal presents an extremely promising method for establishing an ohmic contact with near-quantum-limit contact resistance (Rc) in two-dimensional material (2DM) transistors. However, the physical mechanisms occurring at the interface between 2DMs and semi-metals, which contribute to Rc reduction, are not yet well understood. Leveraging on the contact-end-resistance model applied to the transfer length method structure, we conduct a quantitative and comprehensive characterization of the molybdenum disulfide (MoS2) contact interface with various contact metals. The sheet resistance beneath the semi-metal contact (Rsk) is found to be two orders of magnitude smaller than the sheet resistance of the channel (Rsh), validating the electron doping effect of semi-metals on MoS2 contact areas. Among semi-metals studied, including bismuth (Bi), antimony (Sb), and their alloy, Bi results in the highest electron doping density and the lowest Rsk of 764 Ω/◻, leading to an improvement in Rc down to 526 Ω μm. This work provides a perspective toward the physical mechanisms beneath the semi-metal induced Rc reduction, setting a strong foundation for devising strategies to lower the Rc in 2D-based devices.

Tailoring optical and photocatalytic properties of sulfur-doped boron nitride quantum dots via ligand functionalization

Boron nitride quantum dots (BNQDs) have emerged as promising photocatalysts due to their excellent physicochemical properties. This study investigates strategies to enhance the photocatalytic performance of BNQDs through sulfur-doping (S-BNQDs) and edge-functionalization with ligands (urea, thiourea, p-phenyl-enediamine (PPD)). To analyze the geometry, electronic structure, optical absorption, charge transfer, and photocatalytic parameters of pristine and functionalized S-BNQDs, we performed density functional theory calculations. The results showed that S-doping and ligand functionalization tune the bandgap, band energies, and introduce mid-gap states to facilitate light absorption, charge separation, and optimized energetics for photocatalytic redox reactions. Notably, the PPD ligand induced the most substantial bandgap narrowing and absorption edge red-shift by over 1 electron volt (eV) compared to pristine S-BNQD, significantly expanding light harvesting. Additionally, urea and PPD functionalization increased the charge transfer length by up to 2.5 times, effectively reducing recombination. On the other hand, thiourea functionalization yielded the most favorable electron injection energetics. The energy conversion efficiency followed the order: PPD (15.0%) > thiourea (12.0%) > urea (11.0%) > pristine (10.0%). Moreover, urea functionalization maximized the first-order hyperpolarizability, enhancing light absorption. These findings provide valuable insights into tailoring S-BNQDs through strategic doping and functionalization to develop highly efficient, customized photocatalysts for sustainable applications.

Radiopharmaceuticals for Cancer Diagnosis and Therapy: New Targets, New Therapies-Alpha-Emitters, Novel Targets.

Radiopharmaceutical therapy has emerged as a promising approach for the treatment of various cancers. The exploration of novel targets such as tumor-specific antigens, overexpressed receptors, and intracellular biomolecules using antibodies, peptides, or small molecules has expanded the scope of radiopharmaceutical therapy, enabling precise and effective cancer treatment for an increasing number of tumor types. Alpha emitters, characterized by their high linear energy transfer and short path length, offer unique advantages in targeted therapy due to their potent cytotoxicity against cancer cells while sparing healthy tissues. This article reviews recent advancements in identifying novel targets for radiopharmaceutical therapy and applications in utilizing α-emitters for targeted treatment.

Effects of exposure to elevated temperatures on the transfer length of pretensioned concrete elements

Pretensioned concrete elements are widely used in bridges and precast buildings, which may be exposed to fire. The residual performance of a pretensioned element that has survived a fire event is dependent on the effects of elevated temperatures on steel, concrete, and the bond between these materials. This paper investigates changes in the transfer length of pretensioned beams due to exposure to elevated temperatures. Ten large-scale pretensioned concrete beams with different cross-sectional dimensions and strand layouts were fabricated. The transfer length of these elements was measured using demountable mechanical strain gages. The specimens were subjected to elevated temperature cycles with maximum temperatures of 500 and 700 degrees for two hours. After natural cool down, changes in the transfer length of specimens were determined. The results showed that heat exposure leads to an increase in the transfer length by up to 35% and 42% for maximum temperatures of 500 and 700 degrees Celsius, respectively. Strand arrangement, compressive strength of concrete, cross-sectional dimensions, and clear cover were found to affect the sensitivity of elements to heat exposure. A simplified equation was proposed for estimating the transfer length of pretensioned concrete beams that survive elevated temperatures, which may be used for structural assessment applications.

How to Accurately Determine the Ohmic Contact Properties on n-Type 4H-SiC

The electrical properties of ohmic contacts are classically investigated by using the transfer length method (TLM). In the literature, the TLM patterns are fabricated onto different substrate configurations, especially directly onto the 4H-SiC wafers. But, due to the high doping level of commercial substrates, the current is not confined close to the contact and, in this case, the specific contact resistance (SCR) value is overestimated. In this article, we propose, by the means of simulations, to investigate the influence of the layer under the contact towards the estimation of the SCR. The simulation results highlight that, for an accurate determination of the SCR values, an isolation layer between the contact and the silicon carbide substrate is mandatory. Thus, we have determined the characteristics (doping level and thickness) of a suitable isolation layer compatible with SCR values ranging from 10−3 to 10−6 Ω·cm2.

Effect of Dry Etching to Improve Ohmic Contacts on Bulk, Lightly-Doped β-Ga2O3

Ti/Au is a typical Ohmic metal contact stack to n-type β-Ga2O3 but there have been few systematic studies of the use of pre-exposure of the surface to plasmas prior to metal deposition in order to lower the contact resistance. The effects of Cl2/Ar Inductively Coupled Plasma exposure of Ga2O3 surfaces prior to deposition of Ti/Au (20/80 nm) contacts were examined through circular transfer length method (CTLM) measurements to determine both the contact resistance and specific contact resistivity. ICP source power, which controls ion density in the plasma is found to be more important than ion energy (∼165–490 eV in these experiments). The plasma exposure improved specific contact resistivity by more than a factor of 2 in all cases for lightly n-type (1017 cm−3) Ga2O3 and a minimum value of 2 × 10−4 Ω.cm2 was obtained after heating at 550 °C.

Electrical properties of disordered films of van der Waals semiconductor WS2 on paper.

One of the primary objectives in contemporary electronics is to develop sensors that are not only scalable and cost-effective but also environmentally sustainable. To achieve this goal, numerous experiments have focused on incorporating nanomaterial-based films, which utilize nanoparticles or van der Waals materials, on paper substrates. In this article, we present a novel fabrication technique for producing dry-abraded van der Waals films on paper, demonstrating outstanding electrical characteristics. We assess the quality and uniformity of these films by conducting a spatial resistivity characterization on a 5 × 5 cm2 dry-abraded WS2 film with an average thickness of 25 μm. Employing transfer length measurements with varying channel length-to-width ratios, we extract critical parameters, including sheet resistance and contact resistance. Notably, our findings reveal a resistivity approximately one order of magnitude lower than previous reports. The film's inherent disorder manifests as an asymmetric distribution of resistance values for specific geometries. We explore how this behavior can be effectively modeled through a random resistance network (RRN), which can reproduce the experimentally observed resistance distribution. Finally, we investigate the response of these devices under applied uniaxial strain and apply the RRN model to gain a deeper understanding of this process.

Morphological and Electrical Characterization of AlGaN/GaN Heterostructures Modified By Atomic Layer Etching

Modern microelectronic components for high-power and high-frequency applications based on III-V compound semiconductors offer high break down voltage (GaN: 5 MV/cm and AlN: 15 MV/cm) at low specific on-resistance. However, it requires reliability and reproducibility of the production processes. Going to higher frequencies (5 GHz and beyond) and more integration in consumer electronics, smaller structure sizes are needed. This is going along with increasing demands on the manufacturing processes like dry etching. The main goal is to reach smaller and high controllable etching rates, going down to single atomic layers, low damage, and minimized surface roughness. Atomic layer etching (ALE) represents a key technology in order to achieve such requirements.An ALE process consists of two independent steps forming a repeatable cycle with a specific etching amount per cycle (EPC). First a surface modification is done by a chemical precursor i.e., adsorbing or oxidizing the surface. The second step is the removal of the modified layer, either physically by low energy non-reactive ion bombardment (Plasma Enhanced ALE [PEALE]) or chemically by a reactive species (Thermal ALE). The two steps are separated by an inert gas purge. This purging grants the removal of the chemistry after the first step, preventing further chemical reaction and transporting the chemical products out of the chamber after the second step.In this study, a PEALE conducted on different tools is used, for gate and contact recess study in a AlGaN/GaN heterostructure to form high electron mobility transistors (HEMT) with reduced ohmic contact resistance and threshold voltages. The results show a reduction of ohmic contact resistance at reduced forming temperatures and a linear dependence of the threshold voltage on gate recess depth. In order to determine the etching rate and roughness, atomic force microscopy (AFM) measurements were performed.The PEALE module is either integrated into a cluster tool consisting of atomic layer deposition (ALD) and chemical vapor deposition (CVD) or done in a combined ALD/ALE chamber. This opens the possibility of etching and depositing in-situ, reducing contamination and degradation of the substrate material.By this means, metal insulator semiconductor (MIS)-HEMTS with a recessed gate are studied. The monitoring of the individual processes is achieved by test structures like transfer length method structures (TLM) and metal oxide semiconductor (MOS), which showed the improved electric performance of these devices and may indicate unwanted interface issues, respectively. Additional, pre- and post-treatments could improve the interfaces further. The results will be presented and discussed in terms of ALE process development and optimization.This work was financially supported within the ALEStar project by the government of the Free-state of Saxony and the European Regional Development Fund under grant no. SAB 100402929.

Investigation on interfacial shear performance of concrete strengthened with bonded steel plate

This study investigated the interfacial shear performance of concrete strengthened with bonded steel plate through tests, fracture energy based theoretical analysis and numerical simulation. Firstly, the interfacial shear bearing capacity of concrete strengthened with bonded steel plate having various lengths was experimentally investigated, and the failure mode and bearing capacity were discussed. Secondly, based on fracture theory, fictitious crack hypothesis, concrete failure criteria and bilinear linear softening shear slip model, the interfacial shear capacity was theoretically derived, including the effective interfacial shear stress transfer length, fracture energy and peak interfacial shear bearing capacity. Moreover, the interfacial shear failure behavior was also numerically simulated, and the interfacial shear stress and normal stress during the whole loading and failure process were discussed. The results confirmed that the numerical simulation using the theoretically derived interfacial fracture energy and peak shear strength could give simulation results in good agreement with experimental results. Also, the calculated interfacial bearing capacity using the theoretical approach showed excellent agreement with the experimental results. Furthermore, the influence of bonding length was also theoretically derived using the numerical parametric simulation results, and a revised interfacial shear bearing capacity considering bonding length was further proposed, which was also in good agreement with both experimental and numerical simulation results.

Porous hollow CaO microsphere synthesized by the template-assisted approach for enhanced CO2 capture

The development of cheap, environmentally friendly adsorbents with high adsorption capacity and good cycle stability is of great significance for reducing excessive CO2 emissions. However, the CaO-based adsorbents with low prices and high theoretical adsorption capacity suffer from serious sintering problems and poor cyclic stability. Herein, we synthesized porous hollow CaO microspheres for enhanced CO2 capture by the template-assisted approach, in which the carbon sphere template with different carbon chain lengths were prepared by hydrothermal method. The interaction between carbon chain lengths, morphologies, and properties of CaO-based adsorbents was systematically investigated. The results show that the porous hollow CaO microsphere prepared with a sucrose carbon template possesses a higher initial CO2 adsorption capacity (15.3 mmol g−1) and better cyclic stability after 20 cycles by reducing the mass transfer length of CO2 and buffering the volume expansion. In addition, the kinetics study reveals that the porous hollow spherical morphology can significantly improve the CO2 adsorption kinetics, especially in the chemical control stage, which provides theoretical guidance for the further understanding of the carbonization process. The systematic study marks the significance of precise tailoring of porous hollow CaO microsphere to achieve the desired performance of CO2 adsorption.

Exploring the dual capabilities of BNQDs: a comprehensive study on enhancing photoelectric performance and photoluminescence via ligand functionalization.

Boron nitride quantum dots (BNQDs) are emerging as promising multifunctional nanomaterials for renewable energy and optoelectronics owing to their versatile properties. However, rational design principles to tailor their photoelectric and photoluminescent capabilities remain scarce. This study employs density functional theory (DFT) to provide fundamental insights into using urea, thiourea, and PPD ligands to modulate the bandgap, charge transfer dynamics, and recombination processes of BNQDs. Modeling explains that incorporating specific ligands enables visible light absorption, spatial charge separation, continuous photocatalytic cycling, and high quantum yields in BNQDs. The structure-property relationships established pave the way for targeted synthesis of high-performance BNQD photocatalysts and light emitters. This investigation utilized density functional theory (DFT) with the B3LYP functional and 6-31G(d,p) basis set to optimize the geometries of pristine and ligand-functionalized boron nitride quantum dots (BNQDs). The absorption spectra were generated using time-dependent DFT (TDDFT). A Ti38O76 cluster modeled the TiO2 substrate. The cpcm solvation model in Gaussian 09 defined the toluene solvent. Cohesive energies, charge transfer lengths, recombination rates, and conversion efficiencies were calculated to establish structure-property relationships. Multiwfn analyzed the charge densities. The modeling provides insights into tuning BNQD photocatalytic and photoluminescent properties using specific ligands.