Feasibility of initiating robotic surgery during the early stages of gastrointestinal surgery education.

PURPOSE: Minimally invasive surgery for gastrointestinal cancers is rapidly advancing; therefore, surgical education must be changed. This study aimed to examine the feasibility of early initiation of robotic surgery education for surgical residents. METHODS: The ability of staff physicians and residents to handle robotic surgical instruments was assessed using the da Vinci® skills simulator (DVSS). The short-term outcomes of 32 patients with colon cancer who underwent robot-assisted colectomy (RAC) by staff physicians and residents, supervised by a dual console system, between August 2022 and March 2024 were compared. RESULTS: The performances of four basic exercises were assessed after implementation of the DVSS. Residents required less time to complete these exercises and achieved a higher overall score than staff physicians. There were no significant differences in the short-term outcomes, operative time, blood loss, incidence of postoperative complications, and length of the postoperative hospital stay of the two surgeon groups. CONCLUSION: Based on the evaluation involving the DVSS and RAC results, it appears feasible to begin robotic surgery training at an early stage of surgical education using a dual console system.

Site of distant metastasis affects the prognosis with recurrent/metastatic head and neck squamous cell carcinoma patients treated with Nivolumab.

BACKGROUND: Nivolumab is approved for the treatment of recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). However, the influence of the site of distant metastasis on the efficacy of immune checkpoint inhibitor in R/M HNSCC remains unclear. We investigated the prognosis of R/M HNSCC patients treated with nivolumab, focusing on the site of distant metastasis. METHODS: We reviewed the data of R/M HNSCC patients treated with nivolumab between April 2017 and June 2020 at Saitama Prefectural Cancer Center. The differences in the prognosis were evaluated according to the site of distant metastasis. RESULTS: Of the 41 patients enrolled, 26 (63.4%) had lung metastasis, 7 (17.1%) had bone metastasis, and 4 (9.8%) had liver metastasis. Ten patients (24.4%) had single-organ distant metastasis (lung metastasis in all cases). Univariate analysis identified lung metastasis alone (single-organ distant metastasis) was associated with a significantly better prognosis [HR0.37 (95% CI) 0.14-0.97 p = 0.04], while liver metastasis was associated with a significantly worse prognosis [HR3.86 (95% CI) 1.26-11.8 p = 0.02]. Multivariate analysis identified lung metastasis alone and liver metastasis as independent prognostic factors. While 7 patients (70%) with lung metastasis alone could be continued on nivolumab treatment or received subsequent chemotherapy, only 1 patient (25%) with liver metastasis received subsequent chemotherapy. CONCLUSION: The site of distant metastasis affects the prognosis of R/M HNSCC patients treated with nivolumab. Lung metastasis alone appears to be associated with a better prognosis, in that it allows easier transition to subsequent chemotherapy, while liver metastasis associates with a worse prognosis.

The morphometrical evaluation after uvulopalatopharyngoplasty.

OBJECTIVES: The aim of this study was to evaluate the efficacy of uvulopalatopharyngoplasty (UPPP) and the corresponding postoperative morphometrical changes. METHODS: Patients diagnosed with obstructive sleep apnea syndrome who complained of snoring and apnea were enrolled in this study. Pre- and postoperative tests, including CTs, pharyngeal volume (PV), cross-sectional area (CSA), and six-category morphometrical studies, were performed. RESULTS: Of 11 patients included, 10 showed improvement of symptoms. BMI correlated with the respiratory event index (REI). In terms of PV, there was a significantly wider postoperative area. The rate of change between preoperative REI and postoperative REI (ΔREI) correlated with the amount of change of PV between preoperative PV and postoperative PV (ΔPV). CSA increased postoperatively and correlated with REI. Uvula space (UV) and distance between the hyoid bone and the base of the tongue (HB) increased postoperatively, and posterior airway space (PAS) and epiglottic space (Epi) decreased postoperatively. UV and PAS were significant (p = 0.046, 0.014). UV was related to REI. CONCLUSION: Widening the PV, increasing CSA, and the posterior movement of the tongue base after UPPP surgery were found. The improvement of REI did not depend only on volume. These results suggest that it was important not only to widen the PV but also to improve the shape of the pharynx.

Delineation of prostatic calcification using quantitative susceptibility mapping: Spatial accuracy for magnetic resonance-only radiotherapy planning.

To investigate the spatial accuracy of delineating prostatic calcifications by quantitative susceptibility mapping (QSM) in comparison with computed tomography (CT), we conducted phantom and human studies. Five differently-sized spherical hydroxyapatites mimicking prostatic calcification (pseudo-calcification) were arranged in the order of their sizes at the center of a plastic container filled with gelatin. This calcification phantom underwent magnetic resonance (MR) imaging, including the multiple spoiled gradient-echo sequences (SPGR) for the QSM and CT as a reference. The volume of each pseudo-calcification and center-to-center distance between the pseudo-calcifications delineated by QSM and CT were measured. In the human study, eight patients with prostate cancer who underwent radiation therapy and had some prostatic calcifications were included. The patients underwent CT and SPGR and modified DIXON sequence for MR-only simulation. The hybrid QSM processing combined with the complex signals in the SPGR and water and fat fraction maps estimated from the modified DIXON sequence were used to reconstruct the pelvic susceptibility map in humans. The threshold of CT numbers was set at 130 HU, while the QSM images were manually segmented in the calcification phantom and human studies. In the phantom study, there was an excellent agreement in the pseudo-calcification volumes between QSM and CT (y = 1.02x - 7.38, R2  = 0.99). The signal profiles had similar trends in CT and QSM. The center-to-center distances between the pseudo-calcifications in the phantom were also identical in QSM and CT. The calcification volumes were almost identical between the QSM and CT in the human study (y = 0.95x - 9.32, R2  = 1.00). QSM can offer geometric and volumetric accuracies to delineate prostatic calcifications, similar to CT. The prostatic calcification delineated by QSM may facilitate image-guided radiotherapy in the MR-only simulation workflow.

Low fraction of methane in landfill gas emissions in an industrial waste landfill containing incineration ash and gypsum board waste under anaerobic conditions.

The behaviour of carbon dioxide (CO2) and methane (CH4) emissions at the surface and below the soil cover in an industrial waste landfill under anaerobic operating conditions was evaluated for six years. This landfill contained gypsum board waste and incineration ash - a practice currently allowed because of a change in Japanese regulations. The CO2 and CH4 fluxes decreased throughout the six years of the survey. Almost all of the survey points exhibited fractions of CH4 in landfill gas emissions of <0.5 (mean values: 0.0-0.1 [surface], 0.0-0.3 [subsurface]) under anaerobic conditions. In addition, a relatively high first-order reaction rate constant for the landfill gas emissions (0.3 year-1) was observed. The landfill leachate showed a relatively high sulphate ion (SO4 2-) concentration, although other environmental conditions, such as the pH, oxidation-reduction potential and ammonium concentration, were not at levels that could have inhibited CH4 production. These findings suggest that the low fractions could have been related to the lower amounts of CH4 generation caused by competition between methanogens and sulphate-reducing bacteria (SRB). Therefore, SRB could play a major role in the degradation of organic carbon in the landfill.

Detection of Bacterial DNA During the Process of Sake Production Using Sokujo-Moto.

There are two types of starter cultures used in Japanese rice wine (sake) fermentation, namely, sokujo-moto and yamahai-moto. Analyses of microbiota changes during sake production using yamahai-moto have already been reported. In this study, we analyzed microbiota changes during sake production using sokujo-moto. In addition, we sequenced bacterial DNA from the water used in sake production. The Lactobacillus DNA sequences, which are frequently detected during sake production using yamahai-moto, were not detected during sake production using sokujo-moto, indicating that the Lactobacillus DNA detected in sakes made from yamahai-moto is from the fermentation starter. Most bacterial DNA sequences detected in water were not found in the production samples of sake suggesting that these bacteria do not proliferate during sake production. Thus, most of the bacterial DNA sequences detected during the production may be from the bacterial contamination during the production process.

Photocurrent Generation of Reconstituted Photosystem II on a Self-Assembled Gold Film.

Photosystem II (PSII)-modified gold electrodes were prepared by the deposition of PSII reconstituted with platinum nanoparticles (PtNPs) on Au electrodes. PtNPs modified with 1-[15-(3,5,6-trimethyl-1,4-benzoquinone-2-yl)]pentadecyl disulfide ((TMQ(CH2)15S)2) were incorporated into the QB site of PSII isolated from thermophilic cyanobacterium Thermosynechococcus elongatus. The reconstitution was confirmed by QA-reoxidation measurements. PSII reconstituted with PtNPs was deposited and integrated on a Au(111) surface modified with 4,4'-biphenyldithiol. The cross section of the reconstituted PSII film on the Au electrode was investigated by SEM. Absorption spectra showed that the surface coverage of the electrode was about 18 pmol PSII cm-2. A photocurrent density of 15 nAcm-2 at E = +0.10 V (vs Ag/AgCl) was observed under 680 nm irradiation. The photoresponse showed good reversibility under alternating light and dark conditions. Clear photoresponses were not observed in the absence of PSII and molecular wire. These results supported the photocurrent originated from PSII and moved to a gold electrode by light irradiation, which also confirmed conjugation with orientation through the molecular wire.

Impact of routine recurrent laryngeal nerve monitoring in prone esophagectomy with mediastinal lymph node dissection.

BACKGROUND: The problem of recurrent laryngeal nerve (RLN) paralysis (RLNP) after radical esophagectomy remains unresolved. Several studies have confirmed that intraoperative nerve monitoring (IONM) of the RLN during thyroid surgery substantially decreases the incidence of RLN damage. This study tried to determine the feasibility and effectiveness of IONM of the RLN during thoracoscopic esophagectomy in the prone position for esophageal cancer. METHODS: All 108 patients who underwent prone esophagectomy at Tohoku University Hospital between July 2012 and March 2015 were included in this study. We divided patients into two groups: a control group (No-Monitoring group, surgery without IONM; n = 54) and a study group (Monitoring group, surgery with IONM; n = 54). In Monitoring group, neural stimulation was performed for both RLNs before and after dissection in the thoracic procedure, then for RLNs and vagus nerves (VNs) in the cervical procedure. The feasibility of IONM in Monitoring group and early surgical outcomes were retrospectively compared with those in No-Monitoring group. RESULTS: IONM could be performed for 47 cases (87.0%) in Monitoring group. Reasons for discontinuation were use of muscle relaxants (3 patients), change in thoracotomy procedure (2 patients), past rib bone fracture (1 patient), and allergic shock by transfusion (1 patient). Right RLNPs were identified postoperatively in 4 patients, and left RLNPs in 23 patients. IONM sensitivities were 92.7 and 88.0% for the right and left VNs, respectively. Incidences of postoperative RLNP, aspiration, and primary pneumonia did not differ significantly between groups. CONCLUSIONS: This study confirmed the feasibility and safety of IONM of the RLN for thoracoscopic esophagectomy in the prone position. No significant differences in postoperative outcomes were seen between esophagectomy with and without IONM.

Bacterial DNA Detected in Japanese Rice Wines and the Fermentation Starters.

As Japanese rice wine (sake) brewing is not done aseptically, bacterial contamination is conceivable during the process of sake production. There are two types of the fermentation starter, sokujo-moto and yamahai-moto (kimoto). We identified bacterial DNA found in various sakes, the sokujo-moto and the yamahai-moto making just after sake yeast addition. Each sake has a unique variety of bacterial DNA not observed in other sakes. Although most bacterial DNA sequences detected in the sokujo-moto were found in sakes of different sake breweries, most bacterial DNA sequences detected in the yamahai-moto at the early stage of the starter fermentation were not detected in any sakes. Our findings demonstrate that various bacteria grow and then die during the process of sake brewing, as indicated by the presence of trace levels of bacterial DNA.

Evaluation of a newly developed piezo actuator-driven pulsed water jet system for liver resection in a surviving swine animal model.

BACKGROUND: Preservation of the hepatic vessels while dividing the parenchyma is key to achieving safe liver resection in a timely manner. In this study, we assessed the feasibility of a newly developed, piezo actuator-driven pulsed water jet (ADPJ) for liver resection in a surviving swine model. METHODS: Ten domestic pigs underwent liver resection. Parenchymal transection and vessel skeletonization were performed using the ADPJ (group A, n = 5) or an ultrasonic aspirator (group U, n = 5). The water jet was applied at a frequency of 400 Hz and a driving voltage of 80 V. Physiological saline was supplied at a flow rate of 7 ml/min. After 7 days, the animals were killed and their short-term complications were examined and compared between the two groups. RESULTS: No significant complications, such as massive bleeding, occurred in either group during the surgical procedures. The transection time per transection area was significantly shorter in group A than in group U (1.5 ± 0.3 vs. 2.3 ± 0.5 min/cm(2), respectively, P = 0.03). Blood loss per transection area was not significantly different between groups A and U (9.3 ± 4.2 vs. 11.7 ± 2.3 ml/cm(2), P = 0.6). All pigs in group A survived for 7 days. No postoperative bleeding or bile leakage was observed in any animal at necropsy. CONCLUSION: The present results suggested that the ADPJ reduces transection time without increasing blood loss. ADPJ is a safe and feasible device for liver parenchymal transection.

Site-directed mutagenesis of amino acid residues of D1 protein interacting with phosphatidylglycerol affects the function of plastoquinone QB in photosystem II.

Recent X-ray crystallographic analysis of photosystem (PS) II at 1.9-Å resolution identified 20 lipid molecules in the complex, five of which are phosphatidylglycerol (PG). In this study, we mutagenized amino acid residues S232 and N234 of D1, which interact with two of the PG molecules (PG664 and PG694), by site-directed mutagenesis in Synechocystis sp. PCC 6803 to investigate the role of the interaction in PSII. The serine and asparagine residues at positions 232 and 234 from the N-terminus were mutagenized to alanine and aspartic acid, respectively, and a mutant carrying both amino acid substitutions was also produced. Although the obtained mutants, S232A, N234D, and S232AN234D, exhibited normal growth, they showed decreased photosynthetic activities and slower electron transport from QA to QB than the control strain. Thermoluminescence analysis suggested that this slower electron transfer in the mutants was caused by more negative redox potential of QB, but not in those of QA and S2. In addition, the levels of extrinsic proteins, PsbV and PsbU, were decreased in PSII monomer purified from the S232AN234D mutant, while that of Psb28 was increased. In the S232AN234D mutant, the content of PG in PSII was slightly decreased, whereas that of monogalactosyldiacylglycerol was increased compared with the control strain. These results suggest that the interactions of S232 and N234 with PG664 and PG694 are important to maintain the function of QB and to stabilize the binding of extrinsic proteins to PSII.

[A Case of Severe Hyponatremia Caused by Renal Salt Wasting Syndrome in Oropharyngeal Cancer].

Hyponatremia is one of the electrolyte abnormalities frequently encountered in cancer therapy. Cisplatin is a well-known drug which can raise various adverse events, including hyponatremia. A male with advanced oropharyngeal cancer is presented in the present report, who was treated with radiotherapy with concurrent administration of cisplatin and who underwent a total of three episodes of severe hyponatremia in the course of therapy. The first two attacks of hyponatremia following cisplatin administration were accompanied by dehydration and excessive urination, and the patient recovered in one week with rehydration and salt supplementation. Excessive loss of salt in urine confirmed that these events were caused by renal salt wasting syndrome after cisplatin administration. On the other hand, the third attack was due to the syndrome of inappropriate antidiuretic hormone secretion after surgery for a bone fracture. Estimation of the extracellular fluid volume and salt intake/output balance is always believed to be necessary for the diagnosis and proper management of severe hyponatremia after chemotherapy-based treatment with cisplatin.

The dissection profile and mechanism of tissue-selective dissection of the piezo actuator-driven pulsed water jet as a surgical instrument: laboratory investigation using Swine liver.

BACKGROUND/PURPOSE: The water jet technique dissects tissue while sparing cord-like structures such as blood vessels. The mechanism of such tissue-selective dissection has been unknown. The novel piezo actuator-driven pulsed water jet (ADPJ) system can achieve dissection with remarkably reduced water consumption compared to the conventional water jet; however, the system's characteristics and dissection capabilities on any organ have not been clarified. The purposes of this study were to characterize the physical properties of the novel ADPJ system, evaluate the dissection ability in swine organs, and reveal the mechanism of tissue-selective dissection. METHODS: The pulsed water jet system comprised a pump chamber driven by a piezo actuator, a stainless steel tube, and a nozzle. The peak pressure of the pulsed water jet was measured through a sensing hole using a pressure sensor. The pulsed water jet technique was applied on swine liver in order to dissect tissue on a moving table using one-way linear ejection at a constant speed. The dissection depth was measured with light microscopy and evaluated histologically. The physical properties of swine liver were evaluated by breaking strength tests using tabletop universal testing instruments. The liver parenchyma was also cut with three currently available surgical devices to compare the histological findings. RESULTS: The peak pressure of the pulsed water jet positively correlated with the input voltage (R(2) = 0.9982, p < 0.0001), and this was reflected in the dissection depth. The dissection depth negatively correlated with the breaking strength of the liver parenchyma (R(2) = 0.6694, p < 0.0001). The average breaking strengths of the liver parenchyma, hepatic veins, and Glisson's sheaths were 1.41 ± 0.45, 8.66 ± 1.70, and 29.6 ± 11.0 MPa, respectively. The breaking strength of the liver parenchyma was significantly lower than that of the hepatic veins and Glisson's sheaths. Histological staining confirmed that the liver parenchyma was selectively dissected, preserving the hepatic veins and Glisson's sheaths in contrast to what is commonly observed with electrocautery or ultrasonic instruments. CONCLUSIONS: The dissection depth of liver tissue is well controlled by input voltage and is influenced by the moving velocity and the physical properties of the organ. We showed that the device can be used to assure liver resection with tissue selectivity due to tissue-specific physical properties. Although this study uses an excised organ, further in vivo studies are necessary. The present work demonstrates that this device may function as an alternative tool for surgery due to its good controllability of the dissection depth and ability of tissue selectivity.

Development of a floating constructed wetland for landfill leachate treatment and its potential to remove recalcitrant organic matter.

The development of simple and economical treatment technologies for the removal of recalcitrant organic matter is required to achieve long-term and sustainable treatment of landfill leachates in tropical regions. In this study, we evaluated the fundamental properties required to develop the floating constructed wetland (FCW), which consists of a buoyant planting unit made of foamed glass and cattails. The results showed that foamed glass alone can be used as a planting substrate for cattails. Treatment of a synthetic landfill leachate by a lab-scale FCW demonstrated that the test system effectively and continuously removed recalcitrant organic matter, whereas the control system did not. This removal by FCW was shown to proceed through nearly equal contributions from adsorption and potential biological processes. Furthermore, the effect of introducing an FCW in an actual waste landfill site in Thailand was simulated using the parameters obtained from this study. The simulation indicated that the introduction of the FCW into the stabilisation pond was effective in reducing both leachate volume and recalcitrant organic matter. It is important to determine how much of the stabilisation pond should be covered with the FCW for cost-effectiveness. The FCW is expected to contribute to improving long-term, sustainable, and appropriate management of landfill leachate in tropical developing countries.

Dmrt1 mutation causes a male-to-female sex reversal after the sex determination by Dmy in the medaka.

DMRT1, which is found in many vertebrates, exhibits testis-specific expression during the sexual differentiation period, suggesting a conserved function of DMRT1 in the testicular development of vertebrate gonads. However, functional analyses have been reported only in mammals. The current study focused on the Dmrt1 function in the teleost medaka, Oryzias latipes, which has an XX-XY sex determination system. Although medaka sex is determined by the presence or absence of the Y chromosome-specific gene Dmy, we demonstrated that in one Dmrt1 mutant line, which was found by screening a gene-driven mutagenesis library, XY mutants developed into normal females and laid eggs. Histological analyses of this mutant revealed that the XY mutant gonads first developed into the normal testis type. However, the gonads transdifferentiated into the ovary type. The mutant phenotype could be rescued by transgenesis of the Dmrt1 genomic region. These results show that Dmrt1 is essential to maintain testis differentiation after Dmy-triggered male differentiation pathway.

Experimental application of pulsed laser-induced water jet for endoscopic submucosal dissection: mechanical investigation and preliminary experiment in swine.

BACKGROUND AND AIM: A current drawback of endoscopic submucosal dissection (ESD) for early-stage gastrointestinal tumors is the lack of instruments that can safely assist with this procedure. We have developed a pulsed jet device that can be incorporated into a gastrointestinal endoscope. Here, we investigated the mechanical profile of the pulsed jet device and demonstrated the usefulness of this instrument in esophageal ESD in swine. METHODS: The device comprises a 5-Fr catheter, a 14-mm long stainless steel tube for generating the pulsed water jet, a nozzle and an optical quartz fiber. The pulsed water jet was generated at pulse rates of 3 Hz by irradiating the physiological saline (4°C) within the stainless steel tube with an holmium-doped yttrium-aluminum-garnet (Ho:YAG) laser at 1.1 J/pulse. Mechanical characteristics were evaluated using a force meter. The device was used only for the part of submucosal dissection in the swine ESD model. Tissues removed using the pulsed jet device and a conventional electrocautery device, and the esophagus, were histologically examined to assess thermal damage. RESULTS: The peak impact force was observed at a stand-off distance of 40 mm (1.1 J/pulse). ESD using the pulsed jet device was successful, as the tissue specimens showed precise dissection of the submucosal layer. The extent of thermal injury was significantly lower in the dissected bed using the pulsed jet device. CONCLUSION: The results showed that the present endoscopic pulsed jet system is a useful alternative for a safe ESD with minimum tissue injury.

Influence of oxygen flow rate and compost addition on reduction of organic matter in aerated waste layer containing mainly incineration residue.

Landfilling municipal solid waste incineration (MSWI) residue alkalizes the waste layer, causing a subsequent decrease in microbial activity and a delay in the decomposition of organic matter. In this study, efficiencies of neutralization of the leachate and organic matter decomposition in the waste layer in a column filled with MSWI residue using aeration and compost addition were evaluated. Total organic carbon (TOC) reduction in the waste layer is large at high oxygen flow rate (OFR). To effectively accelerate TOC reduction in the waste layer to which compost was added, a high OFR exceeding that by natural ventilation was required. At day 65, the pH of the leachate when OFR was above 10(2) mol-O2/(day x m3) was lower than that when OFR was below 10(1) mol-O2/(day x m3). At the same OFR, the pH of waste sample was lower than that of waste sample with compost. Although leachate neutralization could be affected by compost addition, TOC reduction in the waste layer became rather small. It is possible that humic substances in compost prevent the decomposition of TOC in MSWI residue.

[Treatments for otorhinolaryngological patients with psychiatric disorders].

There are few systems in place for patients with psychiatric disorders who need treatments for physical complications. In Tokyo, "The Tokyo metropolitan psychiatric emergency system" was established in 1981, and Ome Municipal General Hospital participated in it. Under this system, fifteen patients with psychiatric disorders were treated for otorhinolaryngological diseases in our department from April 2005 to March 2011. We reviewed the fifteen patients. The coexisting psychiatric disorders were schizophrenia in twelve patients, and mental retardation, Korsakoff's syndrome, and Alzheimer's dementia in one patient each, respectively. All the patients had been receiving psychiatric treatment. The otorhinolaryngological diseases were head and neck cancer in nine patients, chronic sinusitis in three patients, and benign salivary gland tumor, cholesteatoma, and epistaxis in one patient each, respectively. Among the fifteen patients, thirteen could complete their treatment, but two dropped out due to exacerbation of their psychiatric symptoms. The therapeutic course is uncertain in otorhinolaryngological diseases occurring concomitantly with psychiatric disorders, especially in head and neck cancer, because it may be difficult to prioritize the problem when determining the treatment options and delivering the treatment. Thus, we should treat patients with psychiatric disorders carefully on a case-by-case basis depending on their psychiatric symptoms. It is also important to cooperate with psychiatrists and patients' families.

Analysis of different self-propulsion types of oil droplets based on electrostatic interaction effects.

This study aims to investigate electrical effects in self-propelled oil droplets and analyze the motion caused by electrical interactions between two droplets. We examine the motion of self-propelled oil droplets in terms of electrical effects; no similar analyses have been reported to date. When an oleic acid droplet is introduced into a surfactant solution, oleic acid is adsorbed at the droplet surface; as a result, the surface becomes negatively charged. However, the electrostatic interaction between oil droplets has not been studied so far. We focus on the chargeability of self-propelled oil droplets, and propose that their motion can be controlled by changing the charge state at the oil/water interface. This is realized by controlling the pH of the surfactant solution. We prepared several aqueous solutions with slightly different pH values, and introduced two oil droplets into each solution to investigate the relationship between the pH value and the correlated motion of the oil droplets. In an aqueous solution at pH 12.00, the two oil droplets showed two types of motion (follow-up and parallel motion), while in an aqueous solution at pH 12.10 they exhibited only one type of motion, i.e., repulsive motion. In order to analyze the three types of motion, we investigated electrical effects on the surface of the oil droplets. First, we measured the zeta potentials of aqueous solutions at pH 12.00 and 12.10, and analyzed the relationship between pH and charge. Furthermore, we calculated the amount of charge and the repulsive force generated on the surface of the oil droplets. For the pH 12.10 solution, the charge of one oil droplet and the repulsive force generated by the charge were found to be -30.79 pC and 282 nN, respectively. Taking into account the driving forces controlling the motion of oil droplets reported in previous studies, this repulsive force could be the driving force of the observed repulsive motion. Based on the experimental results, we inferred that the three types of self-propulsive motion were controlled by electrical effects at the oil/water interface. To further examine these motions, we analyzed the time dependences of the total distance traveled by a droplet and of the distance between oil droplets, as well as the droplet velocities and images of internal convection of oil droplets.

Current state of building demolition and potential for selective dismantling in Vietnam.

In Vietnam, an increase in construction activities together with the absence of recycling-oriented demolition techniques is giving rise to an alarming generation of construction and demolition waste. This study scrutinized the current state of building demolition approaches in Hanoi, Vietnam and evaluated the potential for the selective dismantling, or deconstruction, of reinforced-concrete (RC) houses. Site observations, direct measurement, and interviews were conducted to obtain information on technical, environmental, and economic characteristics of three residential housing sites, each representing a typical current demolition technique (manual, hybrid, and mechanical demolition). A selective dismantling site is proposed based on the collected survey data and published case studies. Our findings confirmed the unsustainability of RC-building demolition practices in Hanoi, which have an average reuse/recycling rate of roughly 3%. The application of selective dismantling will boost the recycling rate to a remarkable 90%, associated with a 55% decrease in greenhouse gas emissions. Even though selective dismantling is more time-consuming and therefore more costly, it results in double the resale value and an eight-fold decrease in disposal costs. The results of a sensitivity analysis indicate that increasing the current disposal fee will significantly improve the feasibility of selective dismantling, suggesting a need for stricter disposal charging mechanisms along with other interventions such as the development of recycling facilities to promote the introduction of this building removal alternative in Vietnam.