Conventional Process Research Articles

Super compact and ultra-wideband bandpass filter with three band notches using triple-mode stepped impedance resonator and defected ground structure

A super-compact ultra-wideband (UWB) microstrip band-pass filter (BPF) with triple-notched bands and wide stopband is proposed in this paper. The super-compactness of the proposed filter is achieved by integrating the modified SCRLH-TL UWB-BPF and backbone-shaped defected ground structure (DGS). The equivalent LC circuit models of the DGS and the modified SCRLH-TL UWB-BPF with the DGS are analyzed to validate their numerical simulation results. To introduce the triple notched-bands to mitigate the interference the two triple-mode SIRs are designed and loaded on the modified UWB-BPF without increasing the circuit size. The proposed filter was fabricated by using a conventional PCB process with the substrate of FR4. The measured 3-dB passband ranges from 2.8 through 10.2 GHz with the fractional bandwidth (FBW) of about 114%. The triple-notched bands with attenuation of more than 15 dB are measured at 4.4, 5.3 and 8.2 GHz, respectively. The filter exhibits a high selectivity with steep skirt property and has a wide upper stopband with an out-of-band rejection of −10 dB at 11.8−20 GHz. Its total dimension, including the rectangular substrate with feed lines, occupies only 16mm × 8 mm.

Modelling Photocatalytic N2 Reduction: Where We Stand and Where We Are Going.

Artificial ammonia synthesis via the Haber-Bosch process is environmentally problematic due to the high energy consumption and corresponding CO2 emissions, produced during the reaction and before hand in hydrogen production upon methane steam reforming. Photocatalytic nitrogen fixation as a greener alternative to the conventional Haber-Bosch process enables us to perform nitrogen reduction reaction (NRR) under mild conditions, harnessing light as the energy source. Herein, we systematically review first-principles calculations used to determine the electronic/optical properties of photocatalysts, N2 adsorption and to expound possible NRR mechanisms. The most commonly studied photocatalysts for nitrogen fixation are usually modified with dopants, defects, co-catalysts and Z-scheme heterojunctions to prevent charge carrier recombination, improve charge separation efficiency and adjust a band gap to for utilizing a broader light spectrum. Most studies at the atomistic level of modeling are grounded upon DFT calculations, wholly foregoing excitation effects paramount in photocatalysis. Hence, there is a dire need to consider methods beyond DFT to study the excited state properties more accurately. Furthermore, a few studies have been examined, which include higher level kinetics and macroscale simulations. Ultimately, we show there is still ample room for improvement with regard to first principles calculations and their integration in multiscale models.

Wire-cut electrical discharge machining of duplex stainless steel: a study

ABSTRACT In this study, the duplex stainless steel is machined using a wire-cut electrical discharge machining process to overcome the issues of poor finishing, lower dimensional accuracy, and rapid wear of cutting tools in conventional machining processes. The higher rate of material removal and superior finish on the machine surface is dependent on kerf loss, which is expressed as the mean kerf width assessed at certain locations. Nevertheless, this approach is typically not effective in explicating the intricacies of true kerf loss due to the random selection of distinctive points. This work proposes an area-based measuring approach to quantify the kerf loss by taking into account any imperfections on the kerf wall. At the pulse on time of 20 μs and current of 3 A, the machining appears not stable. The pulse on time, current, and voltage of 12 µs, 1 A, and 80 V proved suitable for obtaining excellent dimensional precision.

Tissue Processing using Microwave Oven: A Boon for Histology Slide Preparation

Background: Tissue processing is an important step in histology laboratories. Routine tissue processing is time-consuming. Due to the same time factor, microwave tissue processing is now increasingly being used in many histology and pathology laboratories. Objective: To compare the time taken to process the tissues using the routine conventional and microwave methods. Methods: The study was conducted in the Histology laboratory. 100 slides (50 conventional method + 50 microwave method) were processed using both methods, sectioned, stained, and analyzed by an independent observer who was unaware of the processing method. Results: The study showed a significant decrease in processing time by the microwave method (p-value < .0001). Conclusion: The present study concluded that the time taken for dehydrating, clearing, and embedding the tissues in paraffin wax was found to be considerably lower than that taken for the conventional method of tissue processing. Chloroform was used here as a clearing agent, and it had desirable effects. KEYWORDS: Microwave tissue processing, Conventional tissue processing.

Use of Zero-Valent Iron Nanoparticles (nZVIs) from Environmentally Friendly Synthesis for the Removal of Dyes from Water—A Review

This review article addresses the increasing environmental concerns posed by synthetic dyes in water, exploring innovative approaches for their removal with a focus on zero-valent iron nanoparticles (nZVIs) synthesized through environmentally friendly methods. The article begins by highlighting the persistent nature of synthetic dyes and the limitations of conventional degradation processes. The role of nanoparticles in environmental applications is then discussed, covering diverse methods for metallic nanoparticle production aligned with green chemistry principles. Various methods, including the incorporation of secondary metals, surface coating, emulsification, fixed support, encapsulation, and electrostatic stabilization, are detailed in relation to the stabilization of nZVIs. A novel aspect is introduced in the use of plant extract or biomimetic approaches for chemical reduction during nZVI synthesis. The review investigates the specific challenges posed by dye pollution in wastewater from industrial sources, particularly in the context of garment coloring. Current approaches for dye removal in aqueous environments are discussed, with an emphasis on the effectiveness of green-synthesized nZVIs. The article concludes by offering insights into future perspectives and challenges in the field. The intricate landscape of environmentally friendly nZVI synthesis has been presented, showcasing its potential as a sustainable solution for addressing dye pollution in water.

Critical Review on Two-Stage Anaerobic Digestion with H2 and CH4 Production from Various Wastes

Anaerobic digestion (AD) is a promising method for resource recovery from various wastes. Compared to the conventional single-stage AD process, a two-stage AD process with separate H2 and CH4 production provides higher energy recovery efficiency and enhanced operation stability. The stage separation makes it possible to apply optimal conditions for different functional microorganisms in their respective stages. This review elaborates the mechanisms of the two-stage AD process and evaluates recent research trends on this topic. A comprehensive comparison between single- and two-stage AD processes is made from the perspective of biogas production, organics degradation, energy recovery, and operation stability. The main influence factors on the two-stage AD process are discussed, including substrates, inoculum, and operation parameters, such as pH, temperature, etc. Upgrading technologies for the two-stage AD process are assessed. The microbial communities in the two-stage AD process for treating different substrates and the influence factors on microbial systems are also summarized. Furthermore, future research opportunities for enhancing the application of this technology are highlighted.

Identification and assessment of Critical parameters affecting drinking water quality: A case study of water treatment plants of India

Water-borne diseases are common in India and are mostly brought on by shortages and poor quality of potable water. Watercourses receive many effluents, generally residential sewage, due to inadequate sanitation and wastewater treatment. Hence, drinking water treatment plants (DWTPs) face difficulties in meeting the drinking water standards. The current study evaluated the water quality before and after the conventional drinking water treatment process. The water quality was analyzed every month from three major DWTPs in Guwahati, Assam, India for one year. The study showed significant variation in river water turbidity and pathogen levels. During monsoon, river water turbidity reached up to 470 ± 20 NTU, and an increase in pathogen concentration was observed during the dry seasons at low flow conditions. Many times, drinking water turbidity and MPN values exceeded the BIS guideline value in drinking water. The total organic carbon (TOC), one major precursor of disinfection by-products observed in treated drinking water, was found to be in a higher range in water before and after treatment. After treatment, the TOC of (3.25 ± 0.5 mg/L) was found. For better understanding, the water quality was evaluated using the Modified Entropy-weight Water Quality Index (MEWQI) which showed very poor status in the raw water collected from the river Brahmaputra. While the plant's water quality after treatment varied in the category of fair to very good in certain months of the year, but never excellent quality was achieved in any of the selected plants. The results of the sensitivity analysis suggest that turbidity and MPN exhibit the greatest contribution to the WQI of raw water followed by TOC in drinking water. By providing accurate water quality data, this study benefits researchers, policymakers, and water scientists. It also facilitates the adoption of clean production methods to mitigate pollution and enhance water quality.

Simultaneous Emerging Contaminant Removal and H2O2 Generation Through Electron Transfer Carrier Effect of Bi─O─Ce Bond Bridge Without External Energy Consumption.

Conventional advanced oxidation processes (AOPs) require significant external energy consumption to eliminate emerging contaminants (ECs) with stable structures. Herein, a catalyst consisting of nanocube BiCeO particles (BCO-NCs) prepared by an impregnation-hydrothermal process is reported for the first time, which is used for removing ECs without light/electricity or any other external energy input in water and simultaneous in situ generation of H2O2. A series of characterizations and experiments reveal that dual reaction centers (DRC) which are similar to the valence band/conducting band structure are formed on the surface of BCO-NCs. Under natural conditions without any external energy consumption, the BCO-NCs self-purification system can remove more than 80% of ECs within 30min, and complete removal of ECs within 30min in the presence of abundant electron acceptors, the corresponding second-order kinetic constant is increased to 3.62 times. It is found that O2 can capture electrons from ECs through the Bi─O─Ce bond bridge during the reaction process, leading to the in situ production of H2O2. This work will be a key advance in reducing energy consumption for deep wastewater treatment and generating important chemical raw materials.

Process optimization and economic evaluation of continuous multi-column capture for monoclonal antibody – A case study

In recent years, due to significant improvements achieved in upstream processing of monoclonal antibody (mAb) manufacturing, the focus on productivity and cost-effectiveness has shifted towards downstream processing. Protein A affinity chromatography has been widely employed as the capture step for mAb purification and serves as a key driver of economic efficiency on downstream operations. To enhance the purification process and alleviate manufacturing constraints while reducing costs, continuous processing, such as multi-column capture (MCC), has gained attention. This study aimed to establish and optimize the protein A MCC process and to evaluate it with traditional single-column capture mode. Through a series of verification runs, it was determined that there was no significant difference in yield and quality attributes across different loops. Furthermore, annual cost of goods (COGs) was evaluated with the conventional single-column batch process. The results showed that MCC process reduced operation cost by 18 % and almost doubled productivity in the specific scenario.

A novel phosphorus diffusion process for front-side P–N junction fabrication in PERC solar cells

P–N junction technology underlies photovoltaic conversion in passive emitter and rear cell (PERC) solar cells. Although the front-side phosphorus diffusion method for creating P-type PERC cells is well researched, avenues for innovation persist. We introduce a P–N junction fabrication technique for PERC solar cells via precisely controlling the surface doping concentration and junction depth. Through pressure modulation and carefully selected annealing duration at a defined temperature, the technique yields a P–N junction with a surface doping concentration of 2.37 × 1020 cm−3 and a junction depth of 0.29 μm on the front surface of PERC cells. Compared to conventional diffusion processes, our approach results in an average increase of 1.3 mV in open-circuit voltage, 20 mA in short-circuit current, and an efficiency gain of 0.05 %. The maximum efficiency achieved is 23.68 %, representing an improvement of 0.16 %.

Enhancement of Perlite Concrete Properties containing Sustainable Materials by Incorporation of Hybrid Fibers

Utilizing waste resources in concrete manufacturing, while employing alternative components and minimizing the Ordinary Portland Cement (OPC) production, is a matter of great importance owing to several environmental and stability considerations. OPC is the fundamental component implemented in the conventional concrete production process. However, the OPC industry has raised environmental concerns since it produces mass amounts of carbon dioxide (CO2). A more sustainable substance, utilizing metakaolin as pozzolanic material and local ash as a filler can serve as an OPC substitute, thereby reducing the CO2 release into the environment. This work examines the impact of incorporating sustainable recycled copper fibers as well as alkali resistance glass fibers on the properties of perlite structural lightweight aggregate concrete containing local, sustainable materials. The research includes slump, density, and thermal conductivity tests along with tests conducted during the 7, 28, and 60 days of curing for compressive, flexural, and split tensile strength. The concrete was reinforced with 1% hybrid fibers by volume. The results reveal that adding fibers to lightweight concrete reduces the slump and increases density and thermal conductivity, while it also increases the compressive, flexural, and split tensile strengths.

A 36-nW Electrocardiogram Anomaly Detector Based on a 1.5-bit Non-Feedback Delta Quantizer for Always-on Cardiac Monitoring.

An always-on electrocardiogram (ECG) anomaly detector (EAD) with ultra-low power (ULP) consumption is proposed for continuous cardiac monitoring applications. The detector is featured with a 1.5-bit non-feedback delta quantizer (DQ) based feature extractor, followed by a multiplier-less convolutional neural network (CNN) engine, which eliminates the traditional high-resolution analog-to-digital converter (ADC) in conventional signal processing systems. The DQ uses a computing-in-capacitor (CIC) subtractor to quantize the sample-to-sample difference of ECG signal into 1.5-bit ternary codes, which is insensitive to low-frequency baseline wandering. The subsequent event-driven classifier is composed of a low-complexity coarse detector and a systolic-array-based CNN engine for ECG anomaly detection. The DQ and the digital CNN are fabricated in 65-nm and 180-nm CMOS technology, respectively, and the two chips are integrated on board through wire bonding. The measured detection accuracy is 90.6% ∼ 91.3% when tested on the MIT-BIH arrhythmia database, identifying three different ECG anomalies. Operating at 1 V and 1.4 V power supplies for the DQ and the digital CNN, respectively, the measured long-term average power consumption of the core circuits is 36 nW, which makes the detector among those state-of-the-art always-on cardiac anomaly detection devices with the lowest power consumption.

The Effect of Vacuum Brazing Time on the Microstructure and Mechanical Properties of Ti-6Al-4V to 316L Dissimilar Joint Using BNi-2 Filler Metal

Due to the distinct differences in physical and metallurgical properties, it is hard to join titanium alloys to stainless steels directly via conventional welding processes. In this research, the grade 5 titanium alloy was subjected to brazing with austenitic stainless steel through the vacuum furnace, and the process was conducted above the β transition temperature (BTT). In order to reduce brittle intermetallic formation, a nickel base filler metal (Ni-6.6Cr-4.5Si-3B) was employed under a vacuum condition, and the effect of time on the microstructure and mechanical properties of the joints was investigated. The brazing temperature led to the thickening of the interface to 400 µm, toward the titanium alloy, and the FeTi formed adjacent to the diffusion affected zone (DAZ). Moreover, the isothermal solidified zone (ISZ) widened during the whole process, which, led to higher dissolution of the titanium base metal in the ISZ. Because of the widening of the interfaces, there were no Ni-rich compounds or residual filler metal in this region. SEM result showed that TiB strengthening borides, which were distributed after 45 minutes, and this evolution caused an increase in the shear strength of the joint up to 67 MPa. Fractography analyses and XRD results of the fractured surfaces revealed that the Ti2Ni phase, which formed in the athermaly solidified zone (ASZ) during a two-step solidification reaction, caused the brittle fracture in all joints.

Production of ammonium nitrate for nitrogen recovery in a single bioreactor operating at pH 3

Ammonium nitrate (AN), i.e. NH4NO3, is extensively utilized in agricultural, mining, and civil construction sectors, with an annual production of approximately 16 million tons. Although the biological nitrification processes has been proven to be an important alternative to overcome the intensive energy consumption of the conventional chemical process for AN production, it necessitates ample chemical input for stable performance. This study marks the first demonstration of stable AN production from ammonium-rich wastewater employing a purely microbial-derived one-stage process, without the need for external chemical addition. This process functioned through an acidophilic ammonia-oxidizing bacteria (AOB), i.e., Candidatus (Ca.) Nitrosoglobus, which oxidized the ammonium in the feed to nitrite while simultaneously reducing the reactor pH to 3.2−3.4. Under these pH conditions, nitrite was chemically oxidized to nitrate with the provision of oxygen. Long-term bioreactor operation (>230 days) revealed consistent AN production from high ammonium wastewater at a nitrogen loading rate of 0.15 kg N/m3/d. Batch tests revealed that microbial ammonium oxidation was the rate-determining step in the overall AN production process. Further microbial enrichment and process optimization can enhance the microbial ammonium oxidation rate. In summary, the proposed acidic one-stage bioprocess presents a promising avenue for AN production from ammonium-rich wastewater.

Минимизация вероятности ошибки при взвешенном приеме сообщения с двухпозиционной импульсно-кодовой манипуляцией в условиях межсимвольной интерференции

In order to increase the noise immunity of data transmission systems, it is proposed to reduce the level of intersymbol interference by means of orthogonalizing the channel symbols. Orthogonalization is done through determining the orthogonality weight. Presented below is a calculation of the E-criterion for assessing the level of intersymbol interference for the proposed data transmission systems using the pulse-code modulation. For both systems, it was assumed that normalized Butterworth low-pass filters would be used as the shaping filter. It is shown that when signal-to-noise ratios exceed a certain critical value, weighted signal processing provides a lower bit error probability compared to the conventional processing technique. A general analytical expression for the orthogonality weight of channel symbols is given, which ensures a minimum bit error probability.

Influence of ZnO and Pr6O11 incorporation on the structural, thermal, optical, mechanical, and magnetic properties of calcium lithium borate glasses

A new glass of calcium lithium borate with the chemical formula (62.75-x)B2O3 + 20CaO + 0.25Pr6O11 + 17Li2O + xZnO, where x = 0, 2.5, 5, 10, 20 (mol%) have been prepared by conventional melt-quenching process. The amorphous character has been confirmed by the very short-range ordering structural matrices demonstrated through X-ray diffraction.The Raman spectra of the prepared glass revealed an enhancement of host lattice distortions. Differential scanning calorimetry (DSC) estimated the glass transition temperature (Tg), the onset temperature of crystallization (Tc), and the melting temperature (Tm). The glass transition decreased from 441 °C to 431 °C with increasing ZnO content up to 10 mol%. The criteria of glass samples up to 10 % ZnO have higher strength, rigidity and higher level of thermal stability. The physical quantities as density, molar volume, inter-atomic distance, polaron radius, packing density, and oxygen packing density were calculated. The glass density increases while the molar volume decreases with ZnO content. The optical properties of glasses were investigated using UV–Vis spectrophotometer. The addition of ZnO enhances the light absorption in UV–Vis. The results of the calculated direct and indirect optical band gaps decrease from 3.663 eV to 3.233 eV for and from 3.167 eV to 2.648 eV for direct and indirect transitions respectively with the increment of ZnO addition. Additionally, the dispersion energy and static refractive index clearly increase while the oscillator energy declines. The Makishima-Mackenzie’s (M−M) method was employed to ascertain mechanical parameters, including elastic moduli, and Poisson’s ratio. The study revealed an enhancement to the mechanical properties as the content of ZnO increased. Vibrating sample magnetometer (VSM) was used to investigate the magnetic properties of the prepared glass and all samples exhibited a ferromagnetic behavior. The incorporation of ZnO act as glass modifier controlling their physical, optical and mechanical properties making the investigated glasses suitable for various applications.

Dewetting-assisted inkjet printing and optimized solvent mixture of Cd-free InP quantum dots for high-resolution pixel-pattern

Direct-printed quantum dot (QD) patterns utilizing inkjet method are a next-generation alternative to achieve high-resolution quantum dot light-emitting diodes (QLED). However, research on high-resolution pixel patterns is still limited due to issues such as thickness uniformity. In this study, we explored the feasibility of direct printing QLEDs to attain high-resolution pixel-patterned displays. Here, we successfully fabricated arrays of green QLED devices with a resolution of 200 pixels per inch, employing a precise 1 pL fine printer nozzle and optimizing ink formulation to achieve superior surface roughness and uniformity at the desired thickness. The inkjet-printed QD layers demonstrated a surface roughness of 1.9 nm and a flatness ratio of 0.2, comparable to those achieved through conventional spin-coating processes. This investigation offers the potential for extending the methodology to the fabrication of cost-effective, high-resolution full-color QLED displays.

Solar photocatalytic degradation of ciprofloxacin using biochar supported zinc oxide- tungsten oxide photocatalyst.

Ciprofloxacin (CIP) is an antibiotic used to treat bacterial infections. It is not completely broken down during conventional wastewater treatment processes and can persist in the environment, leading to the development of antibiotic-resistant bacteria. This study focuses on the solar photocatalytic degradation CIP using biochar-supported photocatalysts. The photocatalysts developed by combining ZnO and WO3 in different ratios (1:2, 1:1, 2:1) were supported on hemp herd biochar. The photocatalyst made with a ratio of 2:1:1 of ZnO:WO3:biochar (Z2W1H) reported the highest CIP degradation efficiency of 87.3% and TOC removal efficiency of 43.1% at a catalyst dosage of 2g/L, initial CIP concentration of 3mg/L, and treatment time of 150min. Subsequently, the effects of operating parameters on CIP degradation were investigated using central composite design (CCD). About 85.4% degradation efficiency of CIP was obtained at optimum conditions (pH ∼8.4, initial CIP concentration ∼4.4mg/L, catalytic dosage ∼3.4g/L) within 90min. A quadradic model was developed to interpret the linear and interactive effect of operating parameters on the CIP degradation efficiency with 2.24-4.59% error. The adsorption-desorption study showed around 42.21% of adsorbed CIP was desorbed from Z2W1H. Scavenger studies demonstrated that the CIP breakdown was notably done by the superoxide radical (O2•-). The mechanism of CIP degradation was adsorption on biochar and subsequent degradation by photocatalyst. The prevalent degradation reactions such as C-N bond cleavage, decarboxylation, decarbonylation, defluorination, and ring opening lead to formation of various intermediates. The Z2W1H reusability test showed ~ 4.2% decrease in CIP removal efficiency after three cycles.

Nitrogen reduction reaction enhanced by single-atom transition metal catalysts on functionalized graphene: A first-principles study

Ammonia production seeks alternatives to the conventional Haber-Bosch process, with nitrogen reduction reaction (NRR) emerging promising. Addressing the challenge of efficient catalysts, the functionalized graphene-based single atom catalysts (SACs) stand out. While prior studies have favored heteroatom-doped catalysts, the coordination of metal centers with nitrogen atoms remains underexplored. This work investigates transition metal (TM) SACs on nitrogen-doped graphene (N3G) using density functional theory (DFT) for electro-catalytic NRR. Results highlight the stability of V@N3G, Mo@N3G, W@N3G, with binding energies of −7.77, −5.43, and −3.89 eV, respectively. Insights into work function, d-band center, N–N bond, and IR stretching's role in N2 activation are gained through this study. Bader charge analysis reveals electron redistribution between the support and adsorbed N2. Employing Computational Hydrogen Electrode (CHE) method, comparative free energy diagrams for TM@N3G (V, Mo, W) via., enzymatic, consecutive, alternating, and distal pathways outline potential rate determining step (PDS) with and without the Implicit solvation method. Remarkably, W@N3G catalyst exhibits the lowest PDS in the presence of solvation energy, surpassing other catalysts. The multi-adsorption of N2 on W@N3G enhances NRR process, stabilizing intermediates for efficient ammonia production. This computational study sheds light on metal center SACs on functionalized graphene support as a potential electro-catalyst for efficient and stable NRR.

Firm engagement: Scale development and verification

Stakeholder or actor (e.g., firms, employees, and customers) engagement is critical for value co-creation in the service ecosystem. As a provider of an engagement platform in a service ecosystem, the firm plays a critical role in employee and customer engagement. While customer and employee engagement have received much attention, firm engagement research remains unexplored, nonetheless, is critical for the business development and sustainability. There is no scale that has been developed to measure firm engagement. Development of this scale would provide a holistic picture of engagement from a multi-perspective. Following the conventional scale development process, this study developed and verified a scale to measure firm engagement. First, in-depth interviews with 23 managers of companies in different industries were conducted to establish initial items. Subsequently, item purification (N = 397) and validation (N = 398) were performed. The results show that firm engagement consists of eight dimensions from customer and employee perspectives. Specifically, customer engagement orientation includes empathy, employee participation, customer participation, and resource integration while employee engagement orientation includes management participation, corporate culture, interest alignment, and internal service quality. The scale contributes to the engagement literature and human resource management research and has practical implications for firms to improve employee performance and customer experience.