Recyclable aqueous metal adsorbent: Synthesis and Cu(II) sorption characteristics of ternary nanocomposites of Fe3O4 nanoparticles@graphene-poly-N-phenylglycine nanofibers.

Metal pollutant adsorbents are an essential material platform for sustainable environmental remediation, but the adsorbents are typically disposable after sorption, which secondarily contaminates the environment. We report on recyclable Cu(II) adsorbent of deprotonated poly-N-phenylglycine nanofibers (d-PPG NFs)-grafted reduced graphene oxide (rGO) sheets intercalated with Fe3O4 nanoparticles (NPs), which are synthesized via wet chemical process. The adsorption performances of ternary Fe3O4 NPs@rGO-d-PPG NFs and binary Fe3O4 NPs@rGO composites are compared, and the ternary ones exhibit much higher Cu2+-adsorption capacity than binary ones under diverse pH conditions due to both high specific surface area and high cationic affinity of d-PPG NFs that follow the Freundlich adsorption model. Density-functional theory calculation results explain why/how the ternary composites show greater Cu2+ adsorption capability in higher pH environment. The ternary composites present stable, high Cu2+ adsorption capability, irrespective of Co2+ concentration in bimetallic Cu and Co aqueous solution. The Fe3O4 NPs in the ternary composites allow magnet-assisted collection after adsorption batches, whose collection yield is ∼95 % without adsorption capacity degradation in repeated adsorbent reuses over 10 times. This study provides a general, promising pathway to synthesize reusable sorptive materials for water purification/remediation.

An In Vitro Evaluation of the Loosening of Different Interchangeable Abutments in Internal-Connection-Type Implants.

PURPOSE: The aim of this study was to compare the loosening of interchangeable one-piece abutments connected to internal-connection-type implants after cyclic loading. MATERIALS AND METHODS: Four implant abutment groups (n = 7 in each group) with Straumann tissue-level implants were assessed: Straumann solid abutment (group S), Southern Implants solid abutment (group SI), Implant Direct straight abutment (group ID), and Blue Sky Bio regular platform abutment (group BSB). The implant was firmly held in a special jig to ensure fixation. Abutment screws were tightened to manufacturers' recommended torque with a digital torque gauge. The hemispherical loading members were fabricated for the load cell of a universal testing machine to evenly distribute the force on the specimens and to fulfill the ISO 14801:2007 standard. A cyclic loading of 25 N at 30 degrees to the implant's long axis was applied for a duty of a half million cycles. Tightening torques were measured prior to the loading. Removal torques were measured after cyclic loading. The data were analyzed with one-way analysis of variance (ANOVA), and the significance level was set at P < .05. RESULTS: The mean removal torques after cyclic loading were 34.0 ± 1.1 Ncm (group S), 25.0 ± 1.5 Ncm (group SI), 23.9 ± 2.1 Ncm (group ID), and 27.9 ± 1.3 Ncm (group BSB). Removal torques of each group were statistically different in the order of group S > group BSB > groups SI and ID (P < .05). The mean reduction rates were -2.9% ± 3.2% (group S), -21.9% ± 4.8% (group SI), -20.2% ± 7.2% (group ID), and -6.9% ± 4.3% (group BSB) after a half million cycles, respectively. Reduction rates of groups S and BSB were statistically lower than those of groups SI and ID (P < .01). The standard deviation of group S was lower than group BSB. CONCLUSION: The removal torque of the original Straumann abutment was significantly higher than those of the copy abutments. The reduction rate of the groups S and BSB abutments was lower than those of the other copy abutments.

Axial displacement of external and internal implant-abutment connection evaluated by linear mixed model analysis.

PURPOSE: To analyze the axial displacement of external and internal implant-abutment connection after cyclic loading. MATERIALS AND METHODS: Three groups of external abutments (Ext group), an internal tapered one-piece-type abutment (Int-1 group), and an internal tapered two-piece-type abutment (Int-2 group) were prepared. Cyclic loading was applied to implant-abutment assemblies at 150 N with a frequency of 3 Hz. The amount of axial displacement, the Periotest values (PTVs), and the removal torque values(RTVs) were measured. Both a repeated measures analysis of variance and pattern analysis based on the linear mixed model were used for statistical analysis. Scanning electron microscopy (SEM) was used to evaluate the surface of the implant-abutment connection. RESULTS: The mean axial displacements after 1,000,000 cycles were 0.6 µm in the Ext group, 3.7 µm in the Int-1 group, and 9.0 µm in the Int-2 group. Pattern analysis revealed a breakpoint at 171 cycles. The Ext group showed no declining pattern, and the Int-1 group showed no declining pattern after the breakpoint (171 cycles). However, the Int-2 group experienced continuous axial displacement. After cyclic loading, the PTV decreased in the Int-2 group, and the RTV decreased in all groups. SEM imaging revealed surface wear in all groups. CONCLUSION: Axial displacement and surface wear occurred in all groups. The PTVs remained stable, but the RTVs decreased after cyclic loading. Based on linear mixed model analysis, the Ext and Int-1 groups' axial displacements plateaued after little cyclic loading. The Int-2 group's rate of axial displacement slowed after 100,000 cycles.

Tailoring the electrical properties of graphene layers by molecular doping.

It is an essential issue in graphene-based nanoelectronic and optoelectronic devices to tune the electrical properties of graphene layers, while preserving its unique band structure. Here, we report the tuning of electronic properties of single-, bi-, and trilayer mechanically exfoliated graphenes by p-toluenesulfonic acid (PTSA) molecular doping. Raman spectroscopy and charge transport measurements revealed that PTSA molecule imposes n-doping to single-, bi-, and trilayer graphenes. The shift of G and 2D peak frequencies and intensity ratio of single-, bi-, and trilayer graphenes are analyzed as a function of reaction time. The Dirac point is also analyzed as a function of reaction time indicates the n-type doping effect for all single-, bi-, and trilayer graphenes. Our study demonstrates that chemical modification is a simple approach to tailor the electrical properties of single-, bi-, and trilayer graphenes, while maintaining the important electrical assets.

Effects of anodized oxidation or turned implants on bone healing after using conventional drilling or trabecular compaction technique: histomorphometric analysis and RFA.

OBJECTIVES: The aim of this study was to compare the bone healing characteristics adjacent to anodic oxidation and turned surfaces after implant installation using the trabecular compaction technique or the conventional drilling technique in the soft bone area. MATERIAL AND METHODS: A total of 72 implants (36 anodic oxidation surface and 36 turned surface implants) were inserted into the distal end of the femur head of 12 dogs by two different surgical techniques. There were four experimental groups: (1) DT group; drilling+turned, (2) DO group; drilling+oxidation, (3) CT group; compaction+turned, and (4) CO group; compaction+oxidation. The resonance frequency was measured and six specimens/treatment group were obtained at 0, 3 and 8 weeks, postoperatively. Undecalcified ground sections were prepared for histologic and histomorphometric examinations. RESULTS: At week 0, the trabecular compaction groups showed a higher bone to implant contact ratio (BIC) than the conventional drilling groups, regardless of surface types. The CT group showed a higher implant stability quotient (ISQ) than the DT group. At week 3, the oxidation groups showed a higher BIC than the turned groups regardless of the surgical technique used. The CO group showed higher ISQ than the CT group. At week 8, there was no statistically significant difference in BIC and ISQ between the groups. CONCLUSIONS: Surgical technique and implant surface state have an effect on the initial bone response to two-stage implants inserted into trabecular bone regions.

Massive Hydrothorax as a Complication of Percutaneous Nephrolithotomy: A case report / 대한마취과학회지

Percutaneous nephrolithotomy (PCNL) has largely replaced open surgical intervention for the management of renal pelvis calculi as it reduces patient morbidity and shortens hospital stay. However, major complications such as hydrothorax or pneumothorax can be encountered uncommonly. A 64-year-old, 48 kg, female patient underwent PCNL under general anesthesia. The preoperative chest X-ray showed normal findings. Elevated airway pressure was noted and then breathing sounds were not audible on the right lung field during the procedure. A chest X-ray and chest computerized tomographic scan, taken immediately after the operation, showed massive hydrothorax and total collapse in the right lung. After drainage of the pleural effusion via chest tube, the patient recovered completely. Anesthesiologists should be aware that hydrothorax can occur during the PCNL procedure and must be prepared to intervene quickly.

The Effects of the Preoperative Education about Analgesics and Patient-Controlled Analgesia (PCA) on the Consumption of Analgesics after Operation / 대한마취과학회지

BACKGROUND: The purpose of this study is to evaluate the patients' general perception about the analgesics and the effects of the preoperative education about analgesics and patient-controlled analgesia (PCA). METHODS: One hundred patients scheduled for elective gastrectomy were randomly allocated into two groups. In control group (n = 50), patients were given conventional preanesthetic visit with questionnaire survey on PCA one day before operation. In study group (n = 50), patients were sufficiently explained about postoperative analgesia and PCA by anesthesiologist and given precise explanation sheet about PCA. Total amounts of drug used in PCA as well as rescue analgesics, the pain scores, and side effects were compared. RESULTS: 62.2% of patients had much information from various sources that analgesics effects positively in the recovery phase, but actually 73.7% of patients considered that analgesics do not seem to have any influence on the recovery after operation. There was no difference between the amounts of total PCA used, rescue analgesics, and the pain scores. However, the educated patients complained less dizziness at postoperative days (POD) one. Also, the number of patients excluded from study due to the PCA discontinuation secondary to related side effects was less in educated patients (P = 0.025). CONCLUSIONS: Preoperative education about analgesics and PCA failed to demonstrate significant decrease in the amount of analgesics and of pain scores. However, it lowered the incidence of PCA discontinuation due to side effects.

The Effect of H1-Receptor Antagonist on Hemodynamic Change during Anesthesia / 대한마취과학회지

baseline for safe use of a drug. RESULTS: SVR and PVR failed to show statistically significant changes. Heart rates were increased only at 2 minute after administration of chlorpheniramine maleate. Blood pressures were increased but returned to basal level within 4 minutes. Cardiac output showed statistically significant increase until 8 minutes. However, the changes of hemodynamic values were maintained within 20% of basal levels. CONCLUSIONS: Chlorpheniramine maleate is observed to cause statistically significant hemodynamic change after intravenous administration during anesthesia. But the changes were within 20% of basal levels, and we can safely use chlorpheniramine maleate 8 mg IV in the view of hemodynamic changes.

Repeating Cardiac Arrest and One Hour of Cardiopulmonary Resuscitation due to Severe Hyperkalemia after Reperfusion during a Liver Transplantation: A case report / 대한마취과학회지

Liver transplantation still carries considerable risks even if the improvements in surgical and anesthetic techniques lead to a significant decrease in complications. Cardiac arrest during liver transplantation occurs most frequently immediately after the reperfusion due to the influx of hyperkalemic blood from donor liver into a recipient. Cardiac arrest caused by hyperkalemia shows a favorable response to cardiopulmonary resuscitation; however, prolonged cardiopulmonary resuscitation can damage the transplanted liver as well as brain and kidney resulting increased mortality and morbidity rates. The authors experienced repeating cardiac arrest and one hour cardiopulmonary resuscitation due to severe hyperkalemia (8.8 mmol/L) just after the reperfusion during cadaveric liver transplantation. Consciousness was returned 6 hours after operation and vital signs was stable. Transplanted liver well functioned although postoperative course was complicated with acute renal failure, pneumonia and pleural effusion. The patient recovered and discharged 97 days after operation.

Silent Brain Infarcts in First-ever Ischemic Stroke Patients: MRI Findings and Stroke Risk Factors

BACKGROUND AND OBJECTS: It is common to find cerebral infarction without a history of stroke on neuroimaging. This study was to determine the frequency, MRI characteristics of these lesions, and the risk factors related with silent brain infarcts in patients with first-ever ischemic stroke. METHOD: Sixty seven patients with acute ischemic stroke, who hospitalized in our hospital from April 1992 to May 1994, were reviewed. Brain MRI was performed in all patients. We evaluated frequency, site, size, and anatomic location of silent infarcts and compared the risk factors of the patients with silent infarcts with that of the ones without silent infarcts. RESULTS AND CONCLUSIONS: The prevalence of silent infarct was 58.2% ( (39/67). The predilection sites were in the right hemisphere and subcortical area (basal ganglia, thalamus), and their sizes were less than 1 cm mostly. The significant risk factor of silent infarcts was hypertension(P<0.01), and the other risk factors, such as age, sex, DM, and EKG abnormality, were not remarkable.

Magnetic Resonance Angiography: Its Role in Early Thrombolytic Theraphy: Preliminary study

In early thrombolytic therapy for acute focal ischemic stroke, the start of treatment within therapeutic time window is one of the most important thing. Recently, new imaging modalities such as SPECT, transcranial doppler, diffusion/ perfusion-weighted MRI, and MR anglography have been implicated to avoid time consumption and delayed therapy. Of these, MR angiography is nomnvasi and rapid technique to visualize large and medium-sized arteries. We explored the usefulness of MR angiography in early thrombolytic therapy. Arterial occlusion of three patients with severe ischemic stroke were demonstrated on MR anglography and wluch were treated with Urokmase (10, 000-20, 000 units/kg) by intravenous infusion within 2-4 hours after symptom onset. Recanalization and brain lesion was assessed by repeated MR angiography and MRI or CT 24 hours later. Clinical improvement was observed in two patients 5-24 hours after initiation of treatment. In one patient hemorrhagic infarction without clinical deterioration was detected by follow-up computed tomography. Recanalization was documented on repeated MR angiography of three patients. MR angiography can document occlusion of stroke-related vasculature without delay of thrombolytic therapy and repeated MR anglography can reveal whether recanalization has occurred.