Mixing of high-consistency fiber-foam suspensions

Foam-forming has been gaining attention recently to manufacture sustainable packaging and cushioning products in various sectors, including food, automobile and construction [1]. Conventionally, foam suspension is made in a mixing tank at a lower fibre consistency, ≤ 2% resulting in large volumes of water consumption. Besides, the excess moisture from the final foam-formed product needs to be removed by drying. Replacing the current foaming methods with High-consistency foam (HCF) can reduce water consumption, drying energy and equipment footprint. However, increasing the fibre consistency makes the rheology of fibre-foam suspension complex [2], posing challenges in mixing. The present work focuses on mixing this complex suspension to generate a homogeneous HCF by selecting proper impeller geometry, mixing time and surfactant dosage. The lab-scale testing facility consisted of a 0.43 m tall and 0.16 m wide transparent acrylic tank equipped with a top-mount impeller assembly. Three impeller geometries, namely bend-disc, Bakker turbine and high solidity pitched blade turbine, and four impeller combinations were used. Chemi-thermomechanical pulp (CTMP) with a mean fibre length of 2.0 mm, a width of 39 μm and Canadian standard freeness (CSF) of 600 ml was used as the fibre material. The consistency varied from 5% to 15%. An 80/20 mol% mixture of sodium dodecyl sulphate (SDS) and Tween 20 (T 20) was used as the surfactant. The surfactant dosage was varied from 0.5 g/l to 2.0 g/l based on fibre consistency. The quality of the HCF was assessed in terms of air content, foaming time and X-ray microtomography. Preliminary results indicated that the used impeller combination should be selected on the base of fibre consistency. No improvement in the air content was noticed beyond 1.2 g/l surfactant dosage. However, increasing the surfactant dosage reduced foaming time at higher consistencies. Currently, experiments are carried out to understand the role of fibre length and the addition of binders such as guar gum in the mixing. In summary, this work provides an understanding of the mixing geometry and foam chemistry that enables the manufacturing of sustainable packaging products at a much lower water consumption

Pipe rheology of wet coating foams

ObjectivesIn paper and board making, additives have traditionally been added to the pulp suspension before forming. More recently, spray coating of the additives has been developed, which gives such advantages as increased mechanical retention and better wet strength without impairing the sheet uniformity. Spray coating, however, creates mist, has difficulties in dealing with highly viscous fluids and suffers from clogging of the spray nozzles. Foam coating, which is widely used in the textile industry [1], gives the advantages of spray coating without its disadvantages. This technology is currently being developed also for the pulp and paper industry. To engineer processes utilizing foam coating, the complex flow behavior [2,3] of the coating foams must be quantified.Materials and methodsPolyvinyl alcohol (which is a widely used strength additive) and an experimental additive were used as surfactants. Their concentration was widely varied to study the effect of the viscosity and surface tension of the base solution on the foam properties. The air content of foams, generated with a commercial foam generator, was varied between 0.7 and 0.9. The rheological properties of foams were measured with three horizontal pipes (D = 8, 12 and 19 mm). Here, the volumetric flow rate, slip velocity, pressure gradient and bubble size distribution were measured. In the viscosity analysis, the real shear rate at the pipe wall was calculated by applying the Weissenberg-Rabinowitsch correction. Notice that we used a pipe rheometer [4,5,6] instead of a rotational rheometer to minimize the disturbance due to the dying of foam and to measure the foam slip behaviour [3] in process-like conditions. Main conclusionsGenerally, the foam viscosity/slip velocity is a function of air density, air content, solution density, solution viscosity, solution surface tension, bubble size, and shear rate/wall shear stress. These quantities were written in a dimensionless form by using dimensional analysis. Then, by using regression analysis, accurate formulas for the foam viscosity and the slip flow were found that were similar to the theoretically derived formulas presented in Ref. [3].<br/

Nanomaterials for the diagnosis and treatment of head and neck cancers: A review

Head and neck cancer (HNC) is a category of cancers that typically arise from the nose-, mouth-, and throat-lining squamous cells. The later stage of HNC diagnosis significantly affects the patient’s survival rate. This makes it mandatory to diagnose this cancer with a suitable biomarker and imaging techniques at the earlier stages of growth. There are limitations to traditional technologies for early detection of HNC. Furthermore, the use of nanocarriers for delivering chemo-, radio-, and phototherapeutic drugs represents a promising approach for improving the outcome of HNC treatments. Several studies with nanostructures focus on the development of a targeted and sustained release of anticancer molecules with reduced side effects. Besides, nanovehicles could allow co-delivering of anticancer drugs for synergistic activity to counteract chemo-or radioresistance. Additionally, a new generation of smart nanomaterials with stimuli-responsive properties have been developed to distinguish between unique tumor conditions and healthy tissue. In this light, the present article reviews the mechanisms used by different nanostructures (metallic and metal oxide nanoparticles, polymeric nanoparticles, quantum dots, liposomes, nanomicelles, etc.) to improve cancer diagnosis and treatment, provides an up-to-date picture of the state of the art in this field, and highlights the major challenges for future improvements

Cooperativity‐Driven Reactivity of a Dinuclear Copper Dimethylglyoxime Complex

In this report, we present the dinuclear copper(II) dimethylglyoxime (H$_2$dmg) complex [Cu$_2$(H$_2$dmg)(Hdmg)(dmg)]$^+$ (1), which, in contrast to its mononuclear analogue [Cu(Hdmg)$_2$] (2), is subject to a cooperativity-driven hydrolysis. The combined Lewis acidity of both copper centers increases the electrophilicity of the carbon atom in the bridging μ$_2$-O−N=C-group of H$_2$dmg and thus, facilitates the nucleophilic attack of H2O. This hydrolysis yields butane-2,3-dione monoxime (3) and NH$_2$OH that, depending on the solvent, is then either oxidized or reduced. In ethanol, NH$_2$OH is reduced to NH$_4$$^+$, yielding acetaldehyde as the oxidation product. In contrast, in CH$_3$CN, NH$_2$OH is oxidized by Cu$^{II}$ to form N$_2$O and [Cu(CH$_3$CN)4]$^+$. Herein are presented the combined synthetic, theoretical, spectroscopic and spectrometric methods that indicate and establish the reaction pathway of this solvent-dependent reaction

Variable dose interplay effects across radiosurgical apparatus in treating multiple brain metastases

PURPOSE: Normal brain tissue doses have been shown to be strongly apparatus dependent for multi-target stereotactic radiosurgery. In this study, we investigated whether inter-target dose interplay effects across contemporary radiosurgical treatment platforms are responsible for such an observation. METHODS: For the study, subsets ([Formula: see text] and 12) of a total of 12 targets were planned at six institutions. Treatment platforms included the (1) Gamma Knife Perfexion (PFX), (2) CyberKnife, (3) Novalis linear accelerator equipped with a 3.0-mm multi-leaf collimator (MLC), and the (4) Varian Truebeam flattening-filter-free (FFF) linear accelerator also equipped with a 2.5 mm MLC. Identical dose–volume constraints for the targets and critical structures were applied for each apparatus. All treatment plans were developed at individual centers, and the results were centrally analyzed. RESULTS: We found that dose–volume constraints were satisfied by each apparatus with some differences noted in certain structures such as the lens. The peripheral normal brain tissue doses were lowest for the PFX and highest for TrueBeam FFF and CyberKnife treatment plans. Comparing the volumes of normal brain receiving 12 Gy, TrueBeam FFF, Novalis, and CyberKnife were 180–290 % higher than PFX. The mean volume of normal brain-per target receiving 4-Gy increased by approximately 3.0 cc per target for TrueBeam, 2.7 cc per target for CyberKnife, 2.0 cc per target for Novalis, and 0.82 cc per target for PFX. The beam-on time was shortest with the TrueBeam FFF (e.g., 6–9 min at a machine output rate of 1,200 MU/min) and longest for the PFX (e.g., 50–150 mins at a machine output rate of 350 cGy/min). CONCLUSION: The volumes of normal brain receiving 4 and 12 Gy were higher, and increased more swiftly per target, for Linac-based SRS platforms than for PFX. Treatment times were shortest with TrueBeam FFF

Application of “Polyana Kvasova” Mineral Water in the Complex Therapy of Patients with Gastro-esophageal Reflux Disease and Osteochondrosis of the Spine

Aim: To investigate the effectiveness of complex therapy using “Polyana Kvasova” mineral water in patients with GERD and osteochondrosis (OH) of the cervical and thoracic spine. Materials and Methods: The examined patients included 56 Helicobacter pylori (HP)-positive patients with GERD and OH of the cervical and thoracic spine. The examined patients were divided into 2 groups depending on the scheme of complex treatment. All HP-positive patients with GERD and OH underwent standard triple anti-helicobacter therapy and itopride hydrochloride. Group I patients (n=26) received only the above-mentioned regimen. Patients of the II group (n=30) were additionally prescribed 100-150 ml of “Polyana Kvasova” carbonated bicarbonate-sodium mineral water (MW) as a natural antacid, warm, still 4 times a day (1.5 hours before meals and after 45 minutes after – both in the morning and evening) within 1 month. Results: The complex therapy carried out had a positive effect on the endoscopic picture of GERD in patients with cervical and thoracic OH. The decrease in the severity of RE was accompanied by an increase in the number of GERD patients in whom the erosive form of reflux esophagitis was not detected during repeated fibroesophagogastroduodenoscopy (FEGDS) (mainly in the II group of examined patients – 10.0% of patients, p<0.05). The additional prescription of “Polyana Kvasova” MW to the complex treatment increased the frequency of eradication of HP infection by 9.2% – p<0.05 at the background of more pronounced normalization of clinical and endoscopic signs of GERD. Conclusions: 1. GERD is often manifested by atypical extraesophageal symptoms (up to 25.0-27.3% of cases) in patients with OH of the cervical and thoracic spine. 2. The use of standard triple AHT in combination with itopride hydrochloride is an effective method of correcting esophageal and extraesophageal clinical manifestations of GERD in patients with cervical and thoracic spine OH. 3. The additional prescription of “Polyana Kvasova” MW as part of the complex therapy of patients with GERD and OH of the cervical and thoracic regions is a safe, effective method for reducing clinical symptoms, the severity of esophageal lesions with repeated FEGD, and also contributes to increasing the frequency of HP infection eradication in the data patients