Enhanced remediation of Cr(VI)-contaminated soil by modified zero-valent iron with oxalic acid on biochar.

Hexavalent chromium (Cr(VI)) is carcinogenic and widely presented in soil. In this study, modified zero-valent iron (ZVI) with oxalic acid on biochar (OA-ZVI/BC) was prepared using wet ball milling method for the remediation of Cr(VI)-contaminated soil. Microscopic characterizations showed that ZVI were distributed on the biochar uniformly and confirmed the enhanced interface interaction between biochar and ZVI by wet ball milling. Electrochemical analysis indicated the strong electron transfer ability and enhanced corrosion behavior of OA-ZVI/BC. Moreover, inhibitory efficiencies of Cr(VI) removal with the addition of 1,10-phenanthroline suggested abundant Fe2+ generation in OA-ZVI/BC, which might facilitate the reduction of Cr(VI) to Cr(III). Theory calculation further demonstrated the ZVI modified by oxalic acid was more susceptible to solid-solid interfacial reactions with Cr(VI), and more electrons were transferred to Cr(VI). When applied to Cr(VI)-contaminated soil, OA-ZVI/BC could passivate 96.7 % total Cr(VI) and maintained for 90 days. The toxicity characteristic leaching procedure (TCLP) and simple based extraction test (SBET) were used to evaluate the leaching toxicity and bioaccessibility of Cr(VI), respectively. The TCLP-Cr(VI) decreased to 0.11 mg·L-1 after OA-ZVI/BC treatment, much lower than that of soils with ZVI/BC and OA-ZVI remediation (1.5 mg·L-1 and 4.1 mg·L-1). The bioaccessibility of Cr(VI) reduced by 93.5 % after 3-month remediation. Sequential extraction showed that Cr fractions in the soil after OA-ZVI/BC remediation was converted from acetic acid-extractable (HOAc-extractable) to more stable forms (e.g., residual and oxidizable forms). Benefiting from the synergies of oxalic acid, biochar and wet ball milling, OA-ZVI/BC exhibited an excellent performance on the remediation of Cr(VI)-contaminated soil, whose mechanisms involved adsorption, reduction (Fe0/Fe2+, Fe2+/Fe3+) and co-precipitation. This study herein develops a promising ZVI technology in the remediation of heavy metal-contaminated soil.

Aging behavior of biodegradable polylactic acid microplastics accelerated by UV/H2O2 processes.

The usage of biodegradable plastics is expanding annually due to worldwide plastic limits, resulting in a substantial number of microplastics (MPs) particles formed from biodegradable plastic products entering the aquatic environment. Until now, the environmental behaviors of these plastic product-derived MPs (PPDMPs) have remained unclear. In this work, commercially available polylactic acid (PLA) straws and PLA food bags were used to evaluate the dynamic aging process and environmental behavior of PLA PPDMPs under UV/H2O2 conditions. By combining scanning electron microscopy, two-dimensional (2D) Fourier transform infrared correlation spectroscopy (COS) and X-ray photoelectron spectroscopy, it was determined that the aging process of the PLA PPDMPs was slower than that of pure MPs. The 2D-COS analysis revealed that the response orders for the functional groups on the PLA MPs differed during the aging process. The results demonstrated that the oxygen-containing functional groups of the PLA PPDMPs were the first to react. Subsequently, the -C-H and -C-C- structural responses began, and the polymer backbone was ruptured by the aging process. However, the aging of the pure-PLA MPs started with a brief oxidation process and then breakage of the polymer backbones, followed by continuous oxidation. Moreover, compared to the PLA PPDMPs, the pure-PLA MPs exhibited a greater adsorption capacity, which was increased by 88% after aging, whereas those of the two PPDMPs only increased by 64% and 56%, respectively. This work provides new insights into the behaviors of biodegradable PLA MPs in aquatic environments, which is critical for assessing the environmental risks and management policies for degradable MPs.

Simple Co-Precipitation of Iron Minerals for the Removal of Phenylarsonic Acid: Insights into the Adsorption Performance and Mechanism.

In this study, three kinds of iron minerals, ferrihydrite, hematite, and goethite, were prepared by a simple coprecipitation method for the adsorption and removal of phenylarsonic acid (PAA). The adsorption of PAA was explored, and the influences of ambient temperature, pH, and co-existing anions on adsorption were evaluated. The experimental results show that rapid adsorption of PAA occurs within 180 min in the presence of iron minerals, and the adsorption process conforms to a pseudo-second-order kinetic model. The isothermal adsorption of PAA by ferrihydrite, goethite, and hematite agrees with the Redlich-Peterson model. The maximum adsorption capacities of PAA are 63.44 mg/g, 19.03 mg/g, and 26.27 mg/g for ferrihydrite, goethite, and hematite, respectively. Environmental factor experiments illustrated that an alkaline environment will significantly inhibit the adsorption of PAA by iron minerals. CO32-, SiO32-, and PO43- in the environment will also significantly reduce the adsorption performance of the three iron minerals. The adsorption mechanism was analyzed by FTIR and XPS, which indicated that ligand exchange between the surface hydroxyl group and the arsine group leads to the formation of an Fe-O-As bond, and electrostatic attraction between the iron minerals and PAA played an important role in the adsorption.

Ball milling enhanced Cr(VI) removal of zero-valent iron biochar composites: Functional groups response and dominant reduction species.

Zero-valent iron biochar composites (ZVI/BC) have been widely used to remove Cr(VI) from water. However, the application of ZVI/BC prepared by the carbothermal reduction was limited by the non-uniform dispersion of ZVI on the biochar surface. In this work, ball milling technique was introduced to modify ZVI/BC. Results showed that after ball milling, the maximum Langmuir adsorption capacity for Cr(VI) was 117.7 mg g-1 (298 K) which was 2.08 times higher than ZVI/BC. The initial adsorption rate of the Elovich model increased from 4.57 × 102 mg g-1 min-1 to 3.74 × 109 mg g-1 min-1 after ball milling. Dispersibility of ZVI on biochar surface and contact between ZVI and biochar were improved by the ball milling, thus accelerating the electron transfer. Besides, ball milling increased the content of oxygen-containing functional groups in biochar, contributing to the chemisorption of Cr(VI). The response sequence of oxygen-containing functional groups was analyzed by two-dimensional correlation spectroscopy, indicating that Cr(VI) preferentially complexed with phenolic -OH. Shielding experiments showed that Fe (0) was the dominant reducing species with a contribution of 73.4%, followed by surface-bound Fe(II) (21.3%) and dissolved Fe2+ (5.24%). Density functional theory calculations demonstrated that ball milled ZVI/BC improved the adsorption affinity and electron transfer flux towards Cr(VI) by introducing phenolic -OH and Fe (0). Combining all the textural characterization, the Cr(VI) removal mechanism of the ball milled ZVI/BC could be proposed as adsorption, reduction, and precipitation. Eventually, stable Cr-Fe oxides (FeOCr2O3 and Cr1·3Fe0·7O3) were formed. This work not only provides a simple method to modify ZVI/BC to remove Cr(VI) in water efficiently and rapidly, but also improves the mechanistic insight into the Cr(VI) removal by iron-carbon composites via the response sequence of functional group analysis and the quantitative analysis of reducing species.

Modulating the Electronic Coordination Configuration and d-Band Center in Homo-Diatomic Fe2N6 Catalysts for Enhanced Peroxymonosulfate Activation.

The electronic coordination configuration of metal active sites and the reaction mechanism were investigated by constructing homo-diatomic Fe sites for visible-light-assisted heterogeneous peroxymonosulfate (PMS) activation. A novel Fe2N6 catalyst was synthesized by selecting uniform pyridinic-N of graphitic carbon nitride (g-C3N4) as anchoring sites. The results demonstrated that homo-diatomic Fe sites modulated the d-band center and electron delocalization and thus enhanced the PMS activation kinetics (3.58 times vs single-atom Fe catalyst) with kobs of 0.111 min-1 owing to the synergistic effect between adjacent Fe atoms. New Fe-Fe coordination significantly decreased the contribution of the antibonding state in the Fe-O bond due to the coupling of the Fe-3d orbitals, which facilitated the O-O bond cleavage of the Fe2-HOO-SO3 complex with a reduced thermodynamic energy barrier of only -0.29 eV. This work provided comprehensive mechanistic insights into developing homo-diatomic catalysts governed by the coordination configuration and radical pathway for efficient heterogeneous PMS catalysis.

Mechanochemical synthesis of catalysts and reagents for water decontamination: Recent advances and perspective.

This paper aims to provide insights on mechanochemistry as a green and versatile tool to synthesize advanced materials for water remediation. In particular, mechanochemical methodologies for preparation of reagents and catalysts for the removal of organic pollutants are reviewed and discussed, focusing on those materials that, directly or indirectly, induce redox reactions in the contaminants (i.e., photo-, persulfate-, ozone-, and Fenton-catalysts, as well as redox reagents). Methods reported in the literature include surface reactivity enhancement for single-component materials, as well as multi-component material design to obtain synergistic effects in catalytic efficiency and/or reactivity. It was also amply demonstrated that mechanochemical surface activation or the incorporation of catalytic/reactive components boost the generation of reactive species in water by accelerating charge transfer, increasing superficial active sites, and developing pollutant absorption. Finally, indications for potential future developments in this field are debated.

Effective Breaking of the Fluorocarbon Chain by the Interface Bi2O2X···PFOA Complex Strategy via Coordinated Se on Construction of the Internal Photogenerated Carrier Pathway.

The destruction of perfluorooctanoic acid (PFOA) from outside was inhibited by the "barrel spiral" barrier, but the construction of the photocatalyst-PFOA complex provided a direct attack on photogenerated reactive species (RSs). Here, we investigated the bridging ability of bismuth oxychalcogenide (Bi2O2X) for constructing an effective photocarrier pathway to PFOA. The experimental results and DFT calculations showed that a more intense internal access of Bi2O2Se was built via the terminal carboxylate tail, and the weaker electrostatic interaction of Bi-Se bonds helped realize the smaller band gap and slower recombination of photocarriers, thereby inhibiting the invalid annihilation of holes with H2O and facilitating the transformation of electrons to O2-•. The pseudo-first-order rate coefficient (kobs) was 2 and 4 times higher than Bi2O2S and TiO2, respectively, showing the outstanding photocatalytic activity of Bi2O2Se. A broad pH (4-8) adaptability of Bi2O2Se was observed for defluorination, especially in alkali condition. This new understanding may inspire the development of Se-coordinated catalysts.

Efficient catalytic ozonation of bisphenol A by three-dimensional mesoporous CeOx-loaded SBA-16.

Herein, we demonstrated the construction of three-dimensional (3D) cerium oxide (CeOx)/SBA-16 nanocomposites for efficient removal of bisphenol A (BPA) via a catalytic ozonation, with a high BPA mineralization up to 60.9% in 90 min. On one hand, the CeOx/SBA-16 mesoporous structured materials presented large surface area and uniform pore distribution, which was conducive to the adsorption of transformation by-products (TBPs) and then, the mass transfer. On the other hand, CeOx/SBA-16 could enhance the ozone utilization efficiency and meanwhile facilitate the formation of OH, the main reactive oxygen species. Through the exploration of dissoluble organic matters and the identification of the reaction intermediates, two BPA degradation pathways were proposed. This approach reported here will benefit the design and construction of mesoporous structured materials for catalytic elimination of hazards to remediate the environment.

The Different Cardiovascular Outcomes Between Long-Term Efficacy of Hydrophilic and Lipophilic Statin Therapy in Both Asian Diabetic Sexes.

PURPOSE: To evaluate the long-term efficacy of hydrophilic and lipophilic statin therapy for cardiovascular outcomes in Asian diabetic patients. METHOD: Newly diagnosed cases of type 2 diabetes during the period from January 2000 to December 2011 were divided into 2 cohorts on the basis of their statin use, namely hydrophilic statin and lipophilic statin. We used Cox proportional hazard regression models to analyze the risks of cardiovascular outcomes. RESULT: In this study, 12 896 patients used statin, including 4259 patients using hydrophilic statin and 8637 patients using lipophilic statin. With 12-year follow-up, higher incidence rate of coronary artery disease and stroke was noted in the lipophilic statin use instead of hydrophilic statin use. CONCLUSION: According to our long-term cohort study, hydrophilic statin use may be a better choice than lipophilic statin to reduce cardiovascular events in Asian diabetic patients.

Mechanism of Synergistic Effect on Electron Transfer over Co-Ce/MCM-48 during Ozonation of Pharmaceuticals in Water.

The same amount of metal was deposited on the surface of three-dimensional mesoporous MCM-48 by a facile impregnation-calcination method for catalytic ozonation of pharmaceutical and personal-care products in the liquid phase. At 120 min reaction time, Co/MCM-48 and Ce/MCM-48 showed 46.6 and 63.8% mineralization for clofibric acid (CA) degradation, respectively. Less than 33% mineralization was achieved with Co/MCM-48 and Ce/MCM-48 during sulfamethazine (SMZ) ozonation. In the presence of monometallic oxides modified MCM-48 catalysts, total organic carbon (TOC) removal of diclofenac sodium (DCF) was around 80%. The composite Co-Ce/MCM-48 catalyst exhibited significantly higher activity in terms of TOC removal of CA (83.6%), SMZ (51.7%) and DCF (86.8%). Co-Ce/MCM-48 inhibited efficiently the accumulation of small molecular carboxyl acids during ozonation. A detailed research was conducted to detect the nature of material structure and mechanism of catalytic ozonation by using a series of characterizations. The main reaction pathway of CA was determined by the analysis of liquid chromatography-mass spectrometry, in line with the results of frontier electron density calculations that reactive oxygen species (ROSs) were easy to attack negative regions of pharmaceuticals. The Si-O-Si, Co···HO-Si-O-Si-OH···Ce, and O3···Co-HO-Si-O-Si-OH···Ce-OH···O3 basic units in catalysts were constructed to detect the orbit-energy-level difference. The results revealed that a synergistic effect existed at the interface between cobalt and cerium oxides over MCM-48, which facilitated the ROSs sequence in solution with ozone. Therefore, the multivalence redox coupling of Ce4+/Ce3+ and Co3+/Co2+ along with electron transfer played an important role in catalytic ozonation process.

Association between Dipeptidyl Peptidase-4 Inhibitors and Allergic Rhinitis in Asian Patients with Diabetes.

In this retrospective study, we attempted to evaluate the association between dipeptidyl peptidase-4 (DPP-4) inhibitors and allergic rhinitis in patients with diabetes. We analyzed the Longitudinal Health Insurance Database 2000 subdatabase. Our study population included patients with type 2 diabetes (ICD-9-CM 250) between 2009 and 2012, and the study groups were DPP-4 inhibitor users and nonusers. Propensity scores were estimated in a multivariable logistic regression model for the analysis of allergic rhinitis (ICD-9-CM 477.9). Each group consisted of 6204 patients. DPP-4 inhibitor users had a reduced risk of allergic rhinitis (aHR = 0.74, 95% confidence interval (CI) = 0.61-0.90) in all stratifications. Among women, DPP-4 inhibitor users had a lower risk of allergic rhinitis (aHR = 0.67, 95% CI = 0.50-0.90). Among patients aged older than 40 years, DPP-4 inhibitor users had a decreased risk of allergic rhinitis (those aged 40-59: aHR = 0.75, 95% CI = 0.56-0.99; those aged ≧60: aHR = 0.73, 95% CI = 0.54-0.97). Among patients with comorbidities, the risk of allergic rhinitis for DPP-4 inhibitor users was 0.73 (95% CI = 0.60-0.90). High-dose (cumulative defined daily dose ≧648mg) DPP-4 inhibitor users had a decreased risk of allergic rhinitis (aHR = 0.23, 95% CI = 0.15-0.35). Our study revealed that Asian patients with diabetes who used DPP-4 inhibitors had decreased risk of allergic rhinitis, especially for DPP-4 inhibitor treatment in patients who were women, were older than 40 years, had higher diabetes severity scores, were taking higher doses of DPP-4 inhibitors, and had diabetes with comorbidities.

Efficient photocatalytic debromination of 2,2',4,4'-tetrabromodiphenyl ether by Ag-loaded CdS particles under visible light.

Highly active and visible light-driven Ag-loaded CdS photocatalysts were prepared via a hydrothermal synthesis and photodeposition method. The removal and debromination of 2,2',4,4'-tetrabromodiphenyl ether was achieved efficiently using this Ag-loaded CdS under visible light, with a removal efficiency of 100% and a debromination ratio of 44.3% being achieved within 30 min. Both the reaction solvent and the water content were found to have a strong influence on the removal efficiency and the debromination ratio. In addition, the stepwise debromination preference was ortho ≫ para, thereby indicating that the main debromination pathway was electron reduction. The stability and efficiency of these Ag-loaded CdS photocatalysts for the removal of BDE47 were satisfactory, and so our results confirmed the development of a promising visible light-driven catalyst for the removal of polybrominated diphenyl ethers.

Association of Tramadol and Hypoglycemia in Diabetic Asians.

To evaluate the association between tramadol and hypoglycemia in diabetic Asians. The data adopted in this study were derived from a subset of the National Health Insurance (NHI) Research Database, which comprises data on one million randomly sampled beneficiaries enrolled in the NHI program. Patients diagnosed with diabetes (according to the International Classification of Diseases, Ninth Revision, Clinical Modification code 250) were identified from claims data between 1998 and 2011. Diabetic patients aged 20 years or older and prescribed tramadol constituted the tramadol group and other diabetic patients without tramadol use constituted the non-tramadol group. For each tramadol case, one non-tramadol control frequency matched according to age (every 5 years), sex and the year of tramadol use was identified. The tramadol group comprised 12,446 patients and non-tramadol group comprised 11,982 patients. During a mean follow-up of 2 years for the patients in the tramadol group and 2.79 years for those in the non-tramadol group, the overall incidences of hypoglycemia (per 1000 person-years) were 7.37 and 3.77, respectively. According to the multivariable analyses, after baseline characteristics were controlled, the tramadol group exhibited a significantly greater risk of hypoglycemia (hazard ratio (HR) = 1.34, 95% confidence interval (CI) = 1.05⁻1.71) compared with the non-tramadol group. Tramadol use increases hypoglycemia in diabetic Asians. Greater attention must be paid to diabetic Asians with tramadol use.

Pulsed Electrodeposition of Co3 O4 Nanocrystals on One-Dimensional ZnO Scaffolds for Enhanced Electrochemical Water Oxidation.

Pulsed electrodeposition has been introduced to deposit ultrathin flakes of Co3 O4 nanocrystals on ZnO nanorods. By fixing the seeding process, the scaffolding function of ZnO nanorods was studied by varying deposition times (30 s, 60 s, and 90 s) of Co3 O4 at a nucleation current of -1.0 mA cm-2 . The amount of deposited Co3 O4 has a strong influence on the oxygen evolution performance with ZnO scaffolds. To deliver a current density of 10.0 mA cm-2 in neutral solutions (0.5 M K2 SO4 ), the presence of ZnO scaffold electrodes negatively shifted the overpotential by ∼200 mV. In particular, the Co3 O4 /ZnO hybrid nanostructured electrode (60 s) exhibits the lowest onset potential of 1.5 V (vs. reversible hydrogen electrode, RHE). Electrochemical impedance spectra and double layer capacitance showed that the enhanced oxygen evolution activities originated from the improved charge transfer capability and the increased electrochemically active interface between Co3 O4 and ZnO.

Pulsed Electrodeposition of Co3 O4 Nanocrystals on One-Dimensional ZnO Scaffolds for Enhanced Electrochemical Water Oxidation.

Invited for this month's cover are the collaborative groups of Dr. Yun Hau Ng at University of New South Wales, Australia and Dr. Yiming Tang at South China Normal University, China. The front cover picture shows ultrathin Co3 O4 nanoflakes that are deposited on ZnO nanorods by pulsed electrodeposition. The performance of the nanostructured hybrid Co3 O4 /ZnO anode in electrochemical O2 evolution is better than that of neat Co3 O4 . Well-aligned one-dimensional ZnO nanorod arrays are integrated as a scaffold which functions as a "highway" to facilitate improved charge transfer, while the porosity of the anode material allows the penetration of the electrolyte, thus promoting efficient utilization of the catalytically active species. Read the full text of the article at 10.1002/cplu.201800218.

Preparation of fluorinated graphene to study its gas sensitivity.

In this paper, fluorinated graphene was prepared from graphite fluoride by an improved Hummers method. The fluorinated graphene was characterized using an X-ray diffractometer (XRD), transmission electron microscope (TEM), atomic force microscope (AFM) and X-ray photoelectron spectrometer (XPS). Moreover, a gas sensitivity test was carried out. The results show that the fluorinated graphene is composed of about 5 layers prepared by utilising the improved Hummers method. The content of fluorine in fluorinated graphene decreased, mainly due to the fracture of C-F bonds. Fluorinated graphene showed gas sensitivity to ethanol, ammonia, methane and formaldehyde gases. The sensitivity of fluorinated graphene to ammonia is the highest and is 3.5 times the sensitivity of graphene to ammonia. The doping of fluorine atoms was conducive to improving the gas sensitivity of fluorinated graphene.

Efficient photocatalytic degradation of tetrabromodiphenyl ethers and simultaneous hydrogen production by TiO2-Cu2O composite films in N2 atmosphere: Influencing factors, kinetics and mechanism.

TiO2-Cu2O photocatalyst composite film with a heterostructure was synthesized on a copper substrate for 2,2',4,4'-tetrabromodiphenyl ether (BDE47) reduction. First, Cu2O film was synthesized by the electrochemical deposition method, and then TiO2 was coated on the surface of the Cu2O film. The morphology, surface chemical composition and optical characteristics of TiO2-Cu2O film were characterized. The degradation efficiency of BDE47 and hydrogen production by TiO2-Cu2O films was higher than those by pure TiO2 or Cu2O films. The highest BDE47 degradation efficiency of 90% and hydrogen production of 12.7mmolLliq-1 after 150min were achieved by 67%TiO2-Cu2O films. The influencing factors were investigated in terms of film component, solvent condition, and initial pH. A kinetics study demonstrated that BDE47 degradation followed a pseudo-first-order model. Photocatalytic apparent reaction rate constant of BDE47 by TiO2-Cu2O films was 0.0070min-1, which was 3.3 times of that by directly photolysis process. During photocatalytic debrmination process, the photogenerated holes were reserved in the valance band of Cu2O to oxidize methanol. Meanwhile, the partial photogenerated electrons transferred to the conduction band of TiO2 and directly eliminated the ortho-Br of BDE47 and yielded BDE28 and BDE15. The other partial photogenerated electrons reduced protons (H+) to form atomic hydrogen (H°), which could substitute the para-Br of BDE47 and generated BDE17 and produce hydrogen.

Heterogeneous catalytic ozonation of clofibric acid using Ce/MCM-48: Preparation, reaction mechanism, comparison with Ce/MCM-41.

Three-dimensional mesoporous MCM-48 and Ce loaded MCM-48 (Ce/MCM-48) were synthesized by hydrothermal and impregnating methods, respectively. They were characterized by XRD, SEM, TEM, EDS, XPS, N2 adsorption-desorption techniques, and the results showed that Ce/MCM-48 still retained a highly ordered cubic structure. A series of experiments were conducted to study the catalytic activity of Ce/MCM-48 and Ce/MCM-41 for ozonation of clofibric acid in aqueous solution. Total Organic Carbon (TOC) removal efficiency in Ce/MCM-48/O3 can be improved to 64% at 120min reaction time, 54% by Ce/MCM-41/O3, only 24% by MCM-48/O3, 23% by single ozonation. Ce/MCM-48 did not show any adsorption capacity for CA. Effect of initial pH revealed that active sites were surface protonated hydroxyl groups. The restraint of phosphate and sodium hydrogen sulfite (NaHSO3) on the mineralization of CA illustrated more hydroxyl radicals were generated by Ce/MCM-48 catalysts than Ce/MCM-41. The degradation pathway of CA was investigated by the alterations of pH under different conditions. Recycle tests of catalysts demonstrated that compared with Ce/MCM-41, Ce/MCM-48 exhibited more excellent catalytic efficiency and stability because of its unique pore systems.

Minimally invasive endoscope-assisted trans-oral excision of huge parapharyngeal space tumors.

Parapharyngeal space tumors are rare head and neck neoplasms, and most are benign lesions. Complete excision of these tumors is difficult because of the complexity of the surrounding anatomic structures. The algorithm for excision of these tumors is typically based on the tumor's characteristics; excision is performed via approaches such as the trans-oral route, the trans-cervical route, and even a combination of the trans-parotid route and mandibulotomy. However, each of these approaches is associated with some complications. Endoscope-assisted minimally invasive surgery is being increasingly employed for surgeries in the head and neck regions. It has the advantage of leaving no facial scars, and ensures better patient comfort after the operation. Here, we report the use of endoscope-assisted trans-oral surgery for excision of parapharyngeal space tumors. The technique yields an excellent outcome and should be a feasible, safe, and economic method for these patients.