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A novel process modeling tool to facilitate the study of how various process changes in the paper dryer section affect the mill-wide energy system has been developed. A model library with steady-state block models describing paper dryers, heat recovery equipment, and auxiliary systems on component level have been developed using the software Extend. Process models are then created from these block models using graphical programming. In this article, the characteristics of the developed tool are described and a case study where the tool is shown to be useful for analyzing the energy performance of a hybrid dryer section is presented. [ABSTRACT FROM AUTHOR]

A general, dynamic model describing the drying mechanisms of paper has been developed. The model includes shrinkage and predicts temperature, moisture, and pressure profiles. It has been evaluated against steady-state as well as dynamic measurements on a multicylinder paper dryer. The results revealed critical sections where low web strength and maximum gas pressure occur. Measurements of the outer cylinder temperature provide reliable information on the accuracy of the predicted moisture profile since they show the position where the paper surface is dry. [ABSTRACT FROM AUTHOR]

Drying of paper during 2000–2018 is reviewed. The review includes new drying processes, multi-cylinder dryers, tissue and impingement drying, TAD-drying, infrared drying and energy use for drying of paper. It includes general aspects of infrared dryers but not drying of coated papers. Paper quality aspects, paper shrinkage and paper isotherms are not included. Impingement drying has been the most successful new technology with several applications while others such as impulse drying has not been commercialized mainly due to problems with paper quality parameters. One promising development is the introduction of steel instead of cast iron cylinders with increased heat transfer reducing the number of cylinders. Future research should focus on modeling the internal transport phenomena and to couple these phenomena to paper shrinkage and quality parameters. The influence of the fabric for the drying process needs more attention, understanding the drying process for new components such as microfibrillar cellulose in the stock and reducing energy use and increasing the amount of renewable energies for drying of paper. [ABSTRACT FROM AUTHOR]

Controllable production of nanometre-sized structures is an important field of research, and synthesis of one-dimensional objects, such as nanowires, is a rapidly expanding area with numerous applications, for example, in electronics, photonics, biology and medicine. Nanoscale electronic devices created inside nanowires, such as p-n junctions, were reported ten years ago. More recently, hetero-structure devices with clear quantum-mechanical behaviour have been reported, for example the double-barrier resonant tunnelling diode and the single-electron transistor. The generally accepted theory of semiconductor nanowire growth is the vapour-liquid-solid (VLS) growth mechanism, based on growth from a liquid metal seed particle. In this letter we suggest the existence of a growth regime quite different from VLS. We show that this new growth regime is based on a solid-phase diffusion mechanism of a single component through a gold seed particle, as shown by in situ heating experiments of GaAs nanowires in a transmission electron microscope, and supported by highly resolved chemical analysis and finite element calculations of the mass transport and composition profiles.

Biomass is normally a poor thermal conductor with high moisture content. These characteristics not only reduce the calorific value of biomass, but also promote the formation of coke and non-condensable gas during subsequent thermal processing. However, the commercial application of biomass is limited to the high energy and time consumption during drying stage. In this research, a pilot-scale cyclone dryer was designed for efficient drying of biomass and the drying characteristics were explored. Its superiority was revealed via the comparison of two traditional drying methods as blast drying oven and fluidized bed. Results showed that cyclone drying has the highest moisture diffusion coefficient (9.0 × 10−10 m2/s to 1.3 × 10−9 m2/s) and the lowest drying activation energy (18.3 kJ/mol). Its drying time is nearly 10% less than that of fluidized bed drying. Even this value is only about 1/4 of blast drying oven. Experimental results show that most of the free water can be removed in a shorter time in the stage of drying speed reduction in cyclone, especially in the initial stage of drying at the same temperature in the low-temperature zone (60 to 80 ℃). It was found that the cyclone drying technology can dry biomass particles in a short time with low energy consumption. [ABSTRACT FROM AUTHOR]

This paper is concerned with a numerical approach for grain drying process in a packed moving grain dryer, where the grain drying process is regarded as steady process based on a newly proposed steady state equation for moisture content of grain. The present method is compared with antecedent results suggested by Zare (Zare D. Computer simulation of rough rice drying in a batch dryer. Energy Convers Manag 2006;47:3241–54) conducted experiments for moisture content and temperature of grain dried in a fixed bed dryer, and shows good agreement. The present model is then extended to the case of the cylindrical dryer with a packed falling bed. The effects of operating parameters of the dryer (i.e. temperature and flow rate of inlet hot air and moving velocity of packed bed) on moisture content of grain are considered. The present approach can be applied to predict the positional distribution of physical quantities such as temperatures of air and grains as well as the relative humidity of air and the moisture content of grains in an arbitrarily-shaped packed moving grain dryer. [ABSTRACT FROM AUTHOR]

Against the backdrop of a global paper resource shortage, there is a growing need to identify fast-growing tree species capable of producing long-lasting paper. Three plant species namely Broussonetia kazinoki, Broussonetia papyrifera and hybrid paper mulberry, belong to the Broussonetia genus, were collected from China to study their white bark suitability for pulp and papermaking. Their chemical composition revealed that the holocellulose content in Broussonetia kazinoki and Broussonetia papyrifera was more than 80%. The molecular weight distribution of several holocellulose/α-cellulose is observed by GPC, which allows us to better observe the changes of various components on the molecular weight. The yield, lignin, whiteness, and molecular weight of the pulps obtained by NaOH treatment were determined. Optical microscope was used to characterize the fiber length-width ratio and rigidity. Finally, the improvement of the fiber rigidity method based on the Kratky-Porod chain model makes it more theoretical and further reveals the influencing factors of fiber rigidity. This study demonstrates the high potentiality of these three species for papermaking applications. [ABSTRACT FROM AUTHOR]

This study investigates the impact of vapour-phase precursor flow rates—specifically those of trimethylaluminum (TMA) and deionized water (H2O)—on the deposition of aluminum oxide (Al2O3) thin films through atomic layer deposition (ALD). It explores how these flow rates influence film growth kinetics and surface reactions, which are critical components of the ALD process. The research combines experimental techniques with a zero-dimensional theoretical model, designed specifically to simulate the deposition dynamics. This model integrates factors such as surface reactions and gas partial pressures within the ALD chamber. Experimentally, Al2O3 films were deposited at varied TMA and H2O flow rates, with system conductance guiding these rates across different temperature settings. Film properties were rigorously assessed using optical reflectance methods and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The experimental findings revealed a pronounced correlation between precursor flow rates and film growth. Specifically, at 150 °C, film thickness reached saturation at a TMA flow rate of 60 sccm, while at 200 °C, thickness peaked and then declined with increasing TMA flow above this rate. Notably, higher temperatures generally resulted in thinner films due to increased desorption rates, whereas higher water flow rates consistently produced thicker films, emphasizing the critical role of water vapour in facilitating surface reactions. This integrative approach not only deepens the understanding of deposition mechanics, particularly highlighting how variations in precursor flow rates distinctly affect the process, but also significantly advances operational parameters for ALD. These insights are invaluable for enhancing the application of ALD technologies across diverse sectors, including microelectronics, photovoltaics, and biomedical coatings, effectively bridging the gap between theoretical predictions and empirical results. [ABSTRACT FROM AUTHOR]

It has recently been suggested that processes related to water uptake from the tree-stem surface, such as water vapor exchange and rainwater permeation, have implications for forest hydrology. However, few studies have investigated stem surface water uptake itself, and the water permeation pathway has not been elucidated in detail. Based on previous findings that trees with outer bark composed mainly of rhytidome have a high frequency of exfoliation and greater water uptake ability, we hypothesized that exfoliation of the outer bark is the main pathway for water uptake from the outer bark surface to the innermost periderm in these species. We tested this hypothesis in teak, a tropical deciduous hardwood with a high frequency of outer-bark exfoliation. We conducted laboratory experiments using dried bark pieces with different outer-bark shapes to evaluate the rate, amount, and pathway of liquid-phase water permeation of outer-bark surfaces. The rate and amount of water absorption differed markedly among samples. The permeation rate was correlated with the degree of outer-bark exfoliation, and water permeation was observed to begin at exfoliated surfaces. These results support our hypothesis. In addition, the increased water content of bark pieces immediately after the start of the experiment was strongly correlated with the surface roughness of the outer bark, implying that roughness may indicate the water-retention capacity of a given tree species. [ABSTRACT FROM AUTHOR]

Understanding the pore structure of paper and its permeability behavior is important for designing paper-based materials. In this study, the three-dimensional structure of paper was investigated using X-ray computed tomography, and the representative elementary volume (REV) was determined to be 400 × 400 × 450 pixels by the porosity criterion. The pore structural parameters of the REV were experimentally validated. Permeability simulations were carried out in the thickness direction (perpendicular to the paper plane, denoted as the Z direction), horizontal direction (any direction of the paper plane, denoted as the X–Y plane), double outlet, and triple outlet conditions. The simulated permeability in the thickness direction (1.69 µm2) was very close to the experimental value (1.88 µm2). The calculated permeability in the horizontal direction (8.38 µm2) was much greater than that in the thickness direction, revealing that the paper had a high pore connectivity and large pore size in the horizontal direction, giving it a high permeability. Compared with the single outlet case, in the case of the double and triple outlet boundary conditions, more fluid flowed out from the side outlets, and the internal pressure declined faster. This study provides an approach for the structural design and performance optimization of paper-based materials. [ABSTRACT FROM AUTHOR]

Surgery on the growing pediatric nose poses many questions regarding the indications and proper timing. Historically, surgeries on the pediatric nose led to facial growth alterations so many urged caution and waiting until skeletal maturity at the age of 18. However, animal studies showed some promise that facial growth may not be affected. Investigations into effects of pediatric sinus surgery and septal surgery on facial growth showed no issues. The external nose is somewhat different in that minor variations potentially can grow to a cosmetic deformity. However, numerous studies on facial growth show, to date, that it is not affected, and that surgery is safe. The caveat that one uses is the techniques of cartilage sparing and preservation, which have been studied and shown to be safe. There are ways to measure the effectiveness of surgery in relieving nasal airway obstruction both objectively and, more recently, subjectively. It is essential to treat pediatric nasal airway obstruction to avoid other facial growth problems, such as mouth breathing, snoring, malocclusion, and obstructive sleep apnea. [ABSTRACT FROM AUTHOR]

Purpose: To present a set of closed-form analytical equations to create a consistent eye model balance based on clinically measured input parameters in a single step. These models complement the existing iterative approaches in the literature., Methods: Two different approaches are presented, both considering the cornea and lens as equivalent thin lenses. The first, called the Gaussian model, starts by defining the refractive error as the difference between the axial power (or dioptric distance) and the whole eye power, which can be expanded by filling in the formulas for each power. The resulting equation can be solved for either the refractive error, axial length, corneal power, lens power or the distance between the cornea and the lens as a function of the other four parameters. The second approach uses vergence calculations to provide alternative expressions, assuming that the refractive error is located at the corneal plane. Both models are explored for a biometric range typically found in adult human eyes., Results: The Gaussian and vergence models each instantly balance the input data into a working eye model over the human physiological range and far beyond as demonstrated in various examples. The equations of the Gaussian model are more complicated, while the vergence model experiences more singularities, albeit in trivial or highly unlikely parameter combinations., Conclusions: The proposed equations form a flexible and robust platform to create eye models from clinical data. Possible applications lie in creating animal eye models or providing a generic reference for real biometric data and the relationships between the ocular dimensions., (© 2024 The Author(s). Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

Water vapor absorption into a multi-layer simulated corrugated board structure was investigated using magnetic resonance imaging (MRI). Humidity and other ambient conditions considerably affect the strength and durability of corrugated board, and through creep, collapse of the corrugated board structures at unexpectedly low load levels. Currently, water vapor permeation and absorption are investigated with methods that do not elucidate the behavior of individual sheet layers in corrugated board. With MRI, signal intensity changes caused by water absorption can be spatially located and identified, providing a promising tool for the assessment of internal changes in a board, and its interaction with humidity. In this work, simulated corrugated board assemblies, consisting of alternating straight layers of linerboard and fluting material, were constructed, subjected to one-sided high humidity environment and periodically MR imaged to obtain temporal information on water accumulation at high relative humidity. It was observed that, in general, the fluting layers would exhibit higher signal intensities sooner, and by extension, higher water accumulation, when compared to the linerboards. The presented study provides insight into the behavior of paperboards in a double-wall corrugated board structure while under constant high humidity. In the future, actual corrugated board samples could be investigated in periodically fluctuating relative humidity and under constant stress to obtain information on the mechanosorptive creep. [ABSTRACT FROM AUTHOR]

Tissue products such as facial tissue and paper towels have been playing a crucial role in promoting hygiene and maintaining good health, since they are commonly available and widely used nowadays. The production of low-density tissue paper typically involves a key creping process that contains pressing and adhering the wet web onto a high-speed Yankee cylinder, followed by releasing the creped sheet with a stationary creping blade to form periodic micro-folds within the tissue structure. This paper discusses and reviews the mechanisms of tissue creping technology, as well as the factors that impact the creping process and tissue properties. These factors primarily include the dryness of the tissue web, creping rate, properties of the pulp raw material, Yankee coating, crepe doctor blade, and tissue drying machines. It is indicated that the creping process, as a multifaceted and integrated treatment for tissue production, can be significantly enhanced through the concerted efforts of the aforementioned factors to achieve greater creping efficiency. However, further endeavors are necessary to address the constraints stemming from the pilot experimental equipment and data, as well as modeling simulation, to enable a more comprehensive examination of the creping process and its mechanism. This review offers a practical overview and comprehensive understanding of the creping technology and its underlying factors for tissue production. [ABSTRACT FROM AUTHOR]

Vertically free-standing nanowires, synthesized through vapor-based growth, can undergo changes in their growth directions known as kinking. These alterations can significantly influence the physical and chemical properties of nanowires, thereby expanding their potential applications. The occurrence of kinks is commonly associated with variations in vapor, temperature, seed, and/or their combinations. However, the interplay among different growth factors complicates the identification of the dominating factor and, consequently, limits precise control over nanowire morphology. Theoretical models, incorporating factors like supersaturation, wetting angle, nanowire size, and surface/interface energies tied to growth conditions, have been developed to describe and predict kinking during nanowire growth. While a few pivotal parameters, such as surface/interface energies and wetting angles, can be subtly adjusted through minor alterations in growth conditions, accurately predicting the occurrence of kinks remains a practical challenge. Conversely, in the present review, we attempted to elucidate connections between microscopic aspects, such as changes in composition and the formation of defects, and the nucleation and progression of kinks. This effort aims to construct a predictive framework that enhances our understanding of the tendencies in nanowire growth. [ABSTRACT FROM AUTHOR]

Maxillary growth after unilateral closure of surgically induced defects in the hard palate in 6- to 8-week old Beagle puppies was studied. The hard palate except for a 4 mm wide strip of bone in the midline and with its overlaying oral mucoperiosteum was removed. On one side the nasal mucoperiosteum was covered with an autogenous full-thickness skin graft (side SGS) and, on the other side the raw surface (side RS) was left for secondary epithelialization. The animals were killed at 47 to 52 weeks of age. Measurements on the dried skulls of the experimental dogs showed no difference in total maxillary length between the two sides of the maxilla. However, the posterior half of the maxilla was longer in 8 dogs on side SGS and the anterior half of the maxilla was in 7 dogs long on side RS. The palatine suture was displaced towards side RS on all dogs, and the height of the nose was in all dogs greater on side SGS. There was a small consistent tendency that the overall growth was more pronounced on the side with the full-thickness skin graft. It is concluded that reducing the amount of scar tissue by covering raw surfaces with an autogenous full-thickness skin graft is one way to reduce maxillary growth impairment after palatal surgery.

The use of adhesive tape as wound treatment in leprosy cases is described and found to be superior to the classical dressing as regards security and facility of application, and for the rapidity and quality of healing. Its use as a "preventive" treatment is stressed. The results of this study seem to justify the following conclusions: The adhesive tape is easy to handle, it heals the leprosy wounds in about half the time necessary for the classical dressing and it costs about 50 times less.

A total of 23 patients with partly resected mandible were repaired with autogenous bone grafts from the iliac crest and ribs. The reasons for reconstruction are presented in Table 1. The grafts healed without complications in 21 cases. With the exception of two of the cases with gunshot wounds, all patients recovered good mobility of the jaw and satisfactory mandibular contours. The patients had been folloed up for 6 months to 11 years. Radiographic examination at the last examination showed that resorption of the graft had been only slight or moderate. Through marrow-spongious bone grafts are regarded as best from an osteogenetic point of view, our cases showed that good results can be achieved also with solid block grafts. The authors discuss the use of plate osteosynthesis without IMF instead of other types of graft fixation and IMF. In six cases where the area of the graft was loaded with a prosthesis, resorption was not more extensive than in the other cases.

Homologous vessel grafts were tried as substitutes for flexor tendon grafts. Pieces of different lengths were excised from a flexor tendon and replaced by a homologous abdominal aorta graft which was turned inside out and then anastomised by drawing it over the tendon stumps in a cuff-like manner. The grafts became firm, homogeneous and completely tendon-like with very little adhesion but with a tendency to become extended and thus too long to be functional.