Subdural Empyema from Streptococcus suis Infection, South Korea.

In Jeju Island, South Korea, a patient who consumed raw pig products had subdural empyema, which led to meningitis, sepsis, and status epilepticus. We identified Streptococcus suis from blood and the subdural empyema. This case illustrates the importance of considering dietary habits in similar clinical assessments to prevent misdiagnosis.

Three-dimensional visualization of secondary neurulation in chick embryos using microCT.

BACKGROUND: Defects in secondary neurulation play an important role in neural tube defects. Researchers have investigated the processes of secondary neurulation and caudal body formation mainly by microscopic observations and molecular experiments. Although conventional histology is a powerful tool for observing the details of morphology, it has limitations in the presentation of gross three-dimensional (3D) configurations of small embryos. The goal of this study was to visualize secondary neurulation and related structures in chick embryos in Hamburger and Hamilton (HH) stages 10-22 using microCT. RESULTS: The gross morphology of the chick embryo of various developmental stages was well visualized using microCT. Also, the detailed structures of the caudal cell mass (CCM) were presented starting from HH stage 12 to stage 16. The spatiotemporal relationship of CCM with the floor plate of the neural tube and notochord was shown. The dynamic changes of the chordoneural hinge, the cavitation of the secondary neural tube, and the primitive streak were described throughout the early stages of secondary neurulation. CONCLUSIONS: By utilizing the advantages of the microCT technique, our study shed light on the secondary neurulation in early-stage chick embryos and this can be the 3D reference for related structures.

Associations between the working experiences at frontline of COVID-19 pandemic and mental health of Korean public health doctors.

BACKGROUND: Demographic, work environmental, and psychosocial features are associated with mental health of healthcare professionals at pandemic frontline. The current study aimed to find predictors of mental health for public health doctors from working experiences at frontline of COVID-19 pandemic. METHODS: With first-come and first-served manner, 350 public health doctors with experiences of work at COVID-19 frontline participated online survey on August 2020. Mental health was defined using the total scores of the Patient Health Questionnaire-9, the Generalized Anxiety Disorder-7, the Perceived Stress Scale, and the Stanford Presenteeism Scale-6. Multivariate logistic regression models of mental health with lowest Akaike Information Criterion were determined among all combinations of working environments, perceived threats and satisfaction at frontline, and demographics that were significant (P < 0.05) in the univariate logistic regression. RESULTS: Perceived distress, lowered self-efficacy at work, anxiety, and depressive mood were reported by 45.7, 34.6, 11.4, and 15.1% of respondents, respectively. Predictors of poor mental health found in the multivariate logistic regression analyses were environmental (insufficient personal protective equipment, workplace of screening center, prolonged workhours) and psychosocial (fear of infection and death, social stigma and rejection) aspects of working experiences at frontline. Satisfaction of monetary compensation and proactive coping (acceptance and willingness to volunteer at frontline) were predictive of better mental health. CONCLUSIONS: Sufficient supply of personal protective equipment and training on infection prevention at frontline, proper workhours and satisfactory monetary compensation, and psychological supports are required for better mental health of public health doctors at frontline of COVID-19 pandemic.

High Prevalence of Human Immunodeficiency Virus Infection among Inmates in Korean Correctional Facilities.

BACKGROUND: Epidemiological data are crucial in designing policies for the control of human immunodeficiency virus (HIV) infections. There is a lack of data on the epidemiology of HIV in Korean correctional facilities such as jails and prisons. METHODS: Clinical characteristics of the study population were collected through a medical record review. RESULTS: The number of people with HIV infection were 83 and the HIV infection prevalence in correctional facilities of Korea was 0.15%. Among them, 10 (12.0%) were diagnosed with the infection when they were incarcerated. The number of drug users was 38 (45.8%). Syphilis-HIV coinfection was observed in 21 (25.3%) patients. Individuals from the group comprising the drug users were more likely to belong to the lesbian, gay, bisexual, transgender, queer (LGBTQ) community, and had a higher incidence of psychological disorders (31.6% vs. 11.1%, P = 0.029; 50.0% vs. 28.9%, P = 0.049, respectively). CONCLUSION: Inmates of correctional facilities showed a five times higher prevalence of HIV infection in Korea, nearly half of whom were drug users.

Delayed Unilateral Facet Interlocking After a Stable Superior Articular Process Fracture of the Cervical Spine: A Case Report.

A 42-year-old man presented with neck pain after a fall from a tree. Spine computed tomography (CT) illustrated the right C5 superior articular process fracture without displacement. Magnetic resonance imaging (MRI) confirmed the fracture and injury of the posterior ligament complex. Initially he was managed conservatively with a neck brace as there were no signs of instability or vertebral body misalignment. However, three days after discharge, right shoulder weakness and numbness of the right upper arm became prominent. X-rays and CT showed anterior slippage of the C4 vertebral body and locked C4/5 facet ??a fractured bony fragment of the C5 superior articular process was pushed forward by the locked inferior articular process of C4 and invaded the neural foramen. Anterior cervical discectomy and fusion (ACDF) was performed using allograft and plate/screws fixation. Although initial imaging showed no evidence of subluxation, surgeons should be aware of occult instability and the possibility of delayed dislocation associated with the unilateral cervical facet fracture.

Clinical impact and potential utility of non-enhanced computed tomography performed immediately after transarterial chemoembolization for hepatocellular carcinoma.

Background: Intratumoral lipiodol deposition following transarterial chemoembolization (TACE) is associated with the prognosis of hepatocellular carcinoma (HCC) patients. However, there is insufficient evidence regarding the actual clinical significance of the imaging tests conducted to evaluate the lipiodol uptake after TACE. This study evaluates the clinical impact and potential utility of performing immediate post-TACE non-enhanced computed tomography (NECT) on the treatment of HCC. Methods: This retrospective study at a tertiary referral center included patients undergoing their first session of conventional TACE for initial treatment of HCC from November 2021 to December 2022 with available immediate post-TACE NECT. Patients were categorized based on lipiodol uptake into Cohorts A (incomplete uptake with additional treatment before the first follow-up 1 month after TACE), B incomplete uptake without additional treatment before first follow-up), and C (complete uptake). Survival curves for the time to progression (TTP) were estimated using the Kaplan-Meier method and were compared by using the log-rank test. Results: Out of 189 patients, 58 (29.6%) showed incomplete lipiodol uptake; 2 in Cohort A and 56 in Cohort B. Cohort C included 131 patients (69.3%). Cohort B had the highest rate of residual viable tumor (48.2%) 1 month after TACE, compared to the other cohorts (0% in Cohort A and 32.1% in Cohort C). The median TTP of Cohort B was 7.9 months [95% confidence interval (CI): 4.6-15.7 months], significantly shorter than the 15.4 months (95% CI: 10.9-20.9 months) for Cohort C (P=0.03). During follow-up, no progression occurred in Cohort A. Conclusions: Assessment of lipiodol uptake by performing immediate post-TACE NECT can stratify HCC patients and facilitate early prediction of therapeutic response. Identifying suboptimal lipiodol uptake immediately after TACE can aid future treatment adjustments and potentially improving oncologic outcomes.

Mechanical Properties of Cement Mortar Containing Ground Waste Newspaper as Cementitious Material.

In recent years, several studies have reported the recycling of by-products generated by the paper industry and their application to the construction industry. A majority of the existing studies used waste paper sludge ash, and considerable energy is consumed in such incineration processes. This may further contribute to air pollution. In this study, we used waste newspaper (WNP), which underwent a simple crushing process without a separate high-temperature treatment process, and we integrated it in cement mortar. We prepared mortars containing 0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% ground WNP as a cement substitute. Subsequently, the fluidity, compressive strength, tensile strength, carbonation depth, drying shrinkage, and microstructure of the mortars were compared and analyzed. The 28-day compressive strength of the mortar samples with WNP was approximately 3.2-16.1% higher than that of the control sample. The 28-day accelerated carbonation depth of the samples with WNP was approximately 1.03-1.61 mm. Furthermore, their carbonation resistance was approximately 5.2-39.4% higher than that of the control sample. Compressive strength, tensile strength, and carbonation resistance were improved by appropriately using ground WNP as a cement substitute in cement mortar. In this study, the appropriate amount of WNP according to the mechanical properties of cement mortar was found to be 0.4-0.8%, and considering the durability characteristics, the value 0.6 was the most ideal.

Manufacture and Vibration-Damping Effect of Composites for Archery Carbon Fiber-Reinforced Polymer Limb with Glass Fiber-Reinforced Polymer Stabilizer.

Typically, archers prepare two sets of bows for competitions in case of bow breakage, but if the limbs of the bow break during a match, archers can become psychologically disadvantaged, leading to potentially fatal consequences. Archers are very sensitive to the durability and vibration of their bows. While the vibration-damping properties of Bakelite® stabilizer are excellent, its low density and somewhat lower strength and durability are disadvantages. As a solution, we used carbon fiber-reinforced plastic (CFRP) and glass fiber-reinforced plastic (GFRP) for the archery limb with stabilizer, commonly used for the limbs of the bow, to manufacture the limb. The stabilizer was reverse-engineered from the Bakelite® product and manufactured using glass fiber-reinforced plastic in the same shape as the existing product. Analyzing the vibration-damping effect and researching ways to reduce the vibration that occurs during shooting through 3D modeling and simulation, it was possible to evaluate the characteristics and the effect of reducing the limb's vibration by manufacturing archery bows and limbs using carbon fiber- and glass fiber-reinforced composites. The objective of this study was to manufacture archery bows using CFRP and GFRP, and to assess their characteristics as well as their effectiveness at reducing limb vibration. Through testing, the limb and stabilizer that were produced were determined to not fall behind the abilities of the bows currently used by athletes, and they also exhibited a noticeable reduction in vibrations.

A child who presented with cerebral infarction: Clipping combined with bypass surgery of a thrombosed giant aneurysm.

Background: Cerebral aneurysms are not common among children and most of them are presented with subarachnoid hemorrhage or mass effect. Here, we describe a rare case of a pediatric giant aneurysm presented with cerebral infarction. Case Description: A 38-month-old boy visited the emergency room due to left hemiparesis and left central type facial palsy. Initial magnetic resonance imaging showed acute cerebral infarction on the right basal ganglia and coronal radiata. Furthermore, a thrombosed aneurysm with a diameter of 30.57 mm at the frontal branch of the right middle cerebral artery was observed. A right pterional craniotomy with Sylvian dissection was performed. Superior and inferior divisions of the frontal branch originating from the aneurysm were identified. The superior division was cutoff from an aneurysm and clipping saving the inferior division was done. Subsequently, end-to-end anastomosis was done between a parietal branch of the superficial temporal artery and a superior division from the aneurysm. No acute complication from the operation was observed. Motor power of the left upper extremity recovered after rehabilitation, while fine motor impairment remained 6 months after the surgery. Conclusion: This case illustrates successful treatment of a pediatric giant aneurysm with extremely rare presentation of cerebral infarction, under a meticulous surgical plan and ad hoc modification.

Various Substitute Aggregate Materials for Sustainable Concrete.

Concrete is one of the most widely used structural construction materials and has significantly influenced industrial development [...].

A Flexible Piezoelectric Device for Frequency Sensing from PVDF/SWCNT Composite Fibers.

Polymer piezoelectric devices have been widely studied as sensors, energy harvesters, and generators with flexible and simple processes. Flexible piezoelectric devices are sensitive to external stimuli and are attracting attention because of their potential and usefulness as acoustic sensors. In this regard, the frequency sensing of sound must be studied to use flexible piezoelectric devices as sensors. In this study, a flexible piezoelectric device composed of a polymer and an electrode was successfully fabricated. Polyvinylidene fluoride, the active layer of the piezoelectric device, was prepared by electrospinning, and electrodes were formed by dip-coating in a prepared single-walled carbon nanotube dispersion. The output voltage of the external sound was matched with the input frequency through a fast Fourier transform, and frequency matching was successfully performed, even with mechanical stimulation. In a high-frequency test, the piezoelectric effect and frequency domain peak started to decrease sharply at 300 Hz, and the limit of the piezoelectric effect and sensing was observed from 800 Hz. The results of this study suggest a method for developing flexible piezoelectric-fiber frequency sensors based on piezoelectric devices for acoustic sensor systems.

Engineering Characteristics of Cement Composites Containing a Chitosan-Based Polymer and Steel Slag Aggregates.

Recently, sustainable development has attracted significant global attention. Toward this, several studies have been performed on the development of alternative aggregates for mortar or concrete to prevent environmental damage and rapid depletion of natural aggregates. In this study, we investigated the applicability of a chitosan-based polymer (CBP), a biomimetic polymer, to cement mortar using steel slag as a fine aggregate. The CBP was synthesized via an amide coupling reaction among chitosan, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 3-(3,4-dihydroxyphenyl)propionic acid. Upon addition to cement mortar using natural sand or a blast furnace slag aggregate, the CBP contributed toward increasing the compressive strength and tensile strength. However, in mortar mixes using a ferronickel slag aggregate, the tensile strength decreased by ~5.7-25.4% upon CBP addition. Moreover, the CBP reduced the total charge passed through the mixes. In particular, in the mortar mix using the steel slag aggregate, the CBP showed improved chloride-ion penetration resistance. The results showed that the as-prepared CBP was a suitable improving agent and exhibited promising compatibility with cement composites containing steel slag aggregates.

Effect of Cementitious Materials on the Engineering Properties of Lightweight Aggregate Mortars Containing Recycled Water.

With the trend toward taller and larger structures, the demand for high-strength and lightweight cement concrete has increased in the construction industry. Equipment for transporting ready-mixed concrete is frequently used to bring concrete to construction sites, and washing this equipment generates a large amount of recycled water, which is an industrial by-product. In this study, we recycled this water as the pre-wetting water for lightweight aggregate and as mixing water, and we substituted blast furnace slag powder (BS) and fly ash (FA) as cementitious materials (Cm). In addition, we evaluated the fluidity, compressive strength, tensile strength, drying shrinkage, and accelerated carbonation depth of lightweight ternary cementitious mortars (TCMs) containing artificial lightweight aggregate and recycled water. The 28-day compressive strengths of the lightweight TCM specimens with BS and FA were ~47.2-51.7 MPa, except for the specimen with 20% each of BS and FA (40.2 MPa), which was higher than that of the control specimen with 100% OPC (45.9 MPa). Meanwhile, the 28-day tensile strengths of the lightweight TCM specimens containing BS and FA were ~2.81-3.20 MPa, which are ~13.7-29.5% higher than those of the control specimen. In this study, the TCM specimen with 5% each of BS and FA performed the best in terms of the combination of compressive strength, tensile strength, and carbonation resistance.

Effects of Capsule Type on the Characteristics of Cement Mortars Containing Powder Compacted Capsules.

Several studies have been reported on self-healing concrete using bacteria, admixtures, and microcapsules. Among these self-healing techniques, encapsulating cement-based materials is advantageous in that large amounts of self-healing material can be contained in a capsule and released at the cracked site for a targeted reaction. This study produced a powder compacted capsule (PCC) using the droplet and blended manufacturing methods to encapsulate cementitious materials. This study refers to the PCCs as droplet-PCC (D-PCC) and blended-PCC (B-PCC) according to the manufacturing method used. The fluidity, compressive strength, carbonation, drying shrinkage, and water permeability of cement mortar with PCCs were evaluated. The test results show that the flow of the mortar sample using D-PCC was slightly higher than that of the mortar using B-PCC. The compressive strength of the mortar sample with B-PCC was generally higher than that of the mortar sample with D-PCC. The compressive strength of the B-PCC2 sample (with 0.2% of B-PCC) was the highest at all curing ages. This may be because the B-PCC fracture load was higher than that of the D-PCC. In addition, more hydrates were observed in the B-PCC sample than in the D-PCC sample. A crack healing effect was observed in the samples with PCC, regardless of the PCC type. The effect was the greatest in the B-PCC6 sample (with 0.6% of B-PCC). The results of this study provide a reference for the PCC type and mix ratio that would yield the best mechanical properties and crack healing effect.

Effect of Bio-Inspired Polymer Types on Engineering Characteristics of Cement Composites.

Cement concrete is the most commonly used building and construction material worldwide because of its many advantages. Over time, however, it develops cracks due to shrinkage and tension, which may lead to premature failure of the entire structure. Recently, the incorporation of polymers has been explored to improve the overall strength and durability of cement concrete. In this study, two types of chitosan-based bio-inspired polymers (a-BIP and b-BIP) were synthesized and mixed with cement mortar in different proportions (5-20%). The fluidity of the resulting mixtures and the properties of the hardened samples, such as the compressive and tensile strengths, drying shrinkage, and carbonation resistance, were evaluated. The characteristics of the polymers were tuned by varying the pH during their syntheses, and their structures were characterized using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectroscopy. After 28 days of aging, all samples containing BIPs (35.9-41.4 MPa) had noticeably higher compressive strength than the control sample (33.2 MPa). The tensile strength showed a similar improvement (up to 19.1%). Overall, the mechanical properties and durability of the samples were separately dependent on the type and amount of BIP.

Characteristics of Mortars with Blast Furnace Slag Powder and Mixed Fine Aggregates Containing Ferronickel-Slag Aggregate.

Recently, interest in environmentally friendly development has increased worldwide, especially in the construction industry. In this study, blast furnace slag powder (BFSP) and mixed steel fine aggregates were applied to cement mortars to reduce the environmental damage caused by the extraction of natural aggregate and to increase the recycling rate of steel by-products in the construction industry. We investigated the fluidity, compressive strength, tensile strength, accelerated carbonation depth, and chloride ion penetration resistance of mortars with steel slag aggregate and their dependence on the presence or absence of BFSP. Because the recycling rate of ferronickel slag is low and causes environmental problems, we considered mortar samples with mixed fine aggregates containing blast furnace slag fine aggregate (BSA) and ferronickel slag fine aggregate (FSA). The results showed that the 7-day compressive strength of a sample containing both 25% BSA and 25% FSA was nearly 14.8% higher than that of the control sample. This trend is likely due to the high density and angular shape of steel slag particles. The 56-day compressive strength of the sample with BFSP and 50% FSA was approximately 64.9 MPa, which was higher than that of other samples with BFSP. In addition, the chloride ion penetrability test result indicates that the use of BFSP has a greater effect than the use of steel slag aggregate on the chloride ion penetration resistance of mortar. Thus, the substitute rate of steel slag as aggregate can be substantially enhanced if BFSP and steel slag aggregate are used in an appropriate combination.

Effect of Amorphous Metallic Fibers on Strength and Drying Shrinkage of Mortars with Steel Slag Aggregate.

Recently, with increasingly stringent environmental regulations and the depletion of natural aggregate resources, high-quality aggregates have become scarce. Therefore, significant efforts have been devoted by the construction industry to improve the quality of concrete and achieve sustainable development by utilizing industrial by-products and developing alternative aggregates. In this study, we use amorphous metallic fibers (AMFs) to enhance the performance of mortar with steel slag aggregate. Testing revealed that the 28-day compressive strength of the sample with steel slag aggregate and AMFs was in the range of 48.7-50.8 MPa, which was equivalent to or higher than that of the control sample (48.7 MPa). The AMFs had a remarkable effect on improving the tensile strength of the mortar regardless of the use of natural aggregates. With AMFs, the drying shrinkage reduction rate of the sample with 100% steel slag aggregate was relatively higher than that of the sample with 50% natural fine aggregate. Furthermore, the difference in the drying shrinkage with respect to the amount of AMFs was insignificant. The findings can contribute to sustainable development in the construction industry.

Strength, Carbonation Resistance, and Chloride-Ion Penetrability of Cement Mortars Containing Catechol-Functionalized Chitosan Polymer.

There have been numerous recent studies on improving the mechanical properties and durability of cement composites by mixing them with functional polymers. However, research into applying modified biopolymer such as catechol-functionalized chitosan to cement mortar or concrete is rare to the best of our knowledge. In this study, catechol-functionalized chitosan (Cat-Chit), a well-known bioinspired polymer that imitates the basic structures and functions of living organisms and biological materials in nature, was synthesized and combined with cement mortar in various proportions. The compressive strength, tensile strength, drying shrinkage, accelerated carbonation depth, and chloride-ion penetrability of these mixes were then evaluated. In the ultraviolet-visible spectra, a maximum absorption peak appeared at 280 nm, corresponding to catechol conjugation. The sample containing 7.5% Cat-Chit polymer in water (CPW) exhibited the highest compressive strength, and its 28-day compressive strength was ~20.2% higher than that of a control sample with no added polymer. The tensile strength of the samples containing 5% or more CPW was ~2.3-11.5% higher than that of the control sample. Additionally, all the Cat-Chit polymer mixtures exhibited lower carbonation depths than compared to the control sample. The total charge passing through the samples decreased as the amount of CPW increased. Thus, incorporating this polymer effectively improved the mechanical properties, carbonation resistance, and chloride-ion penetration resistance of cement mortar.

Strength and Durability Characteristics of Cement Composites with Recycled Water and Blast Furnace Slag Aggregate.

Recently, interest in sustainable development has been increased. In this regard, efforts have been made to prevent environmental pollution, and research on the recycling of construction industry byproducts has been actively conducted in the construction industry. In South Korea, about 20 million tons of waste wash water from the ready-mixed concrete production process are generated, and some of them are recycled using recycling facilities in a ready-mixed concrete plant, but a significant portion of them is discharged or landfilled without permission, causing environmental problems. To increase the recycling rate of steel slag and reduce environmental pollution in the construction industry, we simultaneously applied blast furnace slag fine aggregate (BSFA) and recycled water (RW) to cement mortar. In this study, to examine the feasibility of RW and BSFA, we evaluated the fluidity, compressive strength, tensile strength, drying shrinkage, carbonation depth, and chloride penetration resistance of cement mortar using RW and BSFA. From the test results, the 28-day compressive strengths of all samples using RW and BSFA were higher than that of the control sample. In the case of samples using RW, as the BSFA replacement ratio was increased, the carbonation depth of the samples decreased. Therefore, when RW and BSFA are used properly, the mechanical properties of cement mortar, carbonation resistance, and chloride ion penetration resistance are expected to be effectively improved.

Simulated and Experimental Investigation of the Mechanical Properties and Solubility of 3D-Printed Capsules for Self-Healing Cement Composites.

In the concrete industry, various R&D efforts have been devoted to self-healing technology, which can maintain the long-term performance of concrete structures, which is important in terms of sustainable development. Cracks in cement composites occur and propagate because of various internal and external factors, reducing the composite's stability. Interest in "self-healing" materials that can repair cracks has led researchers to embed self-healing capsules in cement composites. Overcoming the limitations of polymer capsules produced by chemical manufacturing methods, three-dimensional (3D) printing can produce capsules quickly and accurately and offers advantages such as high material strength, low cost, and the ability to fabricate capsules with complex geometries. We performed structural analysis simulations, experimentally evaluated the mechanical properties and solubility of poly(lactic acid) (PLA) capsules, and examined the effect of the capsule wall thickness and printing direction on cement composites embedded with these capsules. Thicker capsules withstood larger bursting loads, and the capsule rupture characteristics varied with the printing angle. Thus, the capsule design parameters must be optimized for different environments. Although the embedded capsules slightly reduced the compressive strength of the cement composites, the benefit of the encapsulated self-healing agent is expected to overcome this disadvantage.