Management of Surgically Accessible Lymph Nodes Beyond Normal Resection Planes.

This article discusses the management of isolated metastatic lymph nodes for colon and rectal cancer. There are traditionally significant differences in how certain regions of lymph nodes for colon and rectal cancer are managed in the East and West. This has led to the development of the lateral lymph node dissection for rectal cancer and extended lymphadenectomy techniques for colon cancer. This article will evaluate the literature on these techniques and what the surgical and oncological outcomes are at this time. In addition, colon and rectal cancers can occasionally have isolated distant lymph node metastases. These would traditionally be treated as systemic disease with chemotherapy. There is consideration though that these could be treated as similar to isolated liver or lung metastases which have been shown to be able to be treated surgically with good oncological results. The literature for these isolated distant lymph node metastases will be reviewed and treatment options available will be discussed.

A study of dopant incorporation in Te-doped GaAsSb nanowires using a combination of XPS/UPS, and C-AFM/SKPM.

We report the first study on doping assessment in Te-doped GaAsSb nanowires (NWs) with variation in Gallium Telluride (GaTe) cell temperature, using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), conductive-atomic force microscopy (C-AFM), and scanning Kelvin probe microscopy (SKPM). The NWs were grown using Ga-assisted molecular beam epitaxy with a GaTe captive source as the dopant cell. Te-incorporation in the NWs was associated with a positive shift in the binding energy of the 3d shells of the core constituent elements in doped NWs in the XPS spectra, a lowering of the work function in doped NWs relative to undoped ones from UPS spectra, a significantly higher photoresponse in C-AFM and an increase in surface potential of doped NWs observed in SKPM relative to undoped ones. The carrier concentration of Te-doped GaAsSb NWs determined from UPS spectra are found to be consistent with the values obtained from simulated I-V characteristics. Thus, these surface analytical tools, XPS/UPS and C-AFM/SKPM, that do not require any sample preparation are found to be powerful characterization techniques to analyze the dopant incorporation and carrier density in homogeneously doped NWs.

Safety of Transrectal or Transvaginal Drainage of Pelvic Abscesses / Segurança da drenagem transretal ou transvaginal de abscessos pélvicos

Abstract Objective The literature on the safety and long-term sequelae of transrectal and transvaginal drainage of pelvic abscesses is limited. We evaluated the outcomes and safety of pelvic abscess drainage by interventional radiology at our institution. Methods After obtaining institutional review board approval, we retrospectively evaluated the outcomes of transrectal and transvaginal pelvic abscesses drainage using computed tomography, endorectal ultrasound, and or fluoroscopy. Results The study included 26 patients, with an age range of 24 to 88 years old, out of whom 53.8% were men. A total of 46.1% of the participants were African Americans and 26.9% were Caucasians. The average body mass index was 28.4 (range: 15.6 to 41.9). The most common etiology was penetrating abdominal injury (27%), followed by appendectomy (23%), diverticular disease (11.5%), anastomotic leak (11.5%), and disorders of gynecological causes (11.5%). The mean abscess diameter was 6.3 cm (range: 3.3 to 10.0 cm). Transrectal drainage was performed in all except one patient who had a transvaginal drainage. Transrectal ultrasound was used for drainage in 92.3% cases, and fluoroscopy was used as an additional imaging modality in 75% of the cases. An 8- or 10-Fr pigtail catheter was used in>80% of the patients. Drains were removed between 2 and 7 days in 92.3% of the cases. The average follow-up was 30.4 months (range: 1 to 107 months), and no long-term complications were reported. Only one patient required subsequent operative intervention for an anastomotic leak. Conclusions Pelvic abscess drainage by transrectal route using radiological guidance is a safe and effective procedure.

Resumo Objetivo A literatura sobre a segurança e as sequelas no longo prazo da drenagem transretal e transvaginal do abscesso pélvico é limitada. Avaliamos os resultados e a segurança da drenagem do abscesso pélvico por radiologia intervencionista em nossa instituição. Métodos Após obter a aprovação do conselho de revisão institucional, avaliamos retrospectivamente os resultados da drenagem de abscessos pélvicos transretais e transvaginais por meio de tomografia computadorizada, ultrassom endorretal, e/ou fluoroscopia. Resultados Participaram do estudo 26 pacientes, com faixa etária de 24 a 88 anos, dos quais 53,8% eram homens. Um total de 46,1% eram afro-descendentes, e 26,9% eram brancos. O índice de massa corporal médio foi de 28,4 (gama: 15,6 a 41,9). A etiologia mais comum foi lesão abdominal penetrante (27%), seguida de apendicectomia (23%), doença diverticular (11,5%), fístula anastomótica (11,5%) e distúrbios de causas ginecológicas (11,5%). O diâmetro médio do abscesso foi de 6,3 cm(gama: 3,3 a 10,0 cm). A drenagem transretal foi realizada em todos os pacientes, com exceção de uma, que foi submetida a uma drenagem transvaginal. A ultrassonografia transretal foi utilizada para drenagem em 92,3% dos casos, e a fluoroscopia como modalidade adicional de imagem, em 75% dos casos. Um catéter duplo J de 8 ou 10 Fr foi usado em>80% dos pacientes. Os drenos foram retirados entre 2 e 7 dias em 92,3% dos casos. O acompanhamentomédio foi de 30,4meses (gama: 1 a 107 meses), e nenhuma complicação de longo prazo foi relatada. Apenas um paciente necessitou de intervenção cirúrgica subsequente para um vazamento anastomótico. Conclusão A drenagem do abscesso pélvico por via transretal com orientação radiológica é um procedimento seguro e eficaz.

Study of patterned GaAsSbN nanowires using sigmoidal model.

This study presents the first report on patterned nanowires (NWs) of dilute nitride GaAsSbN on p-Si (111) substrates by self-catalyzed plasma-assisted molecular beam epitaxy. Patterned NW array with GaAsSbN of Sb composition of 3% as a stem provided the best yield of vertical NWs. Large bandgap tuning of ~ 75 meV, as ascertained from 4 K photoluminescence (PL), over a pitch length variation of 200-1200 nm has been demonstrated. Pitch-dependent axial and radial growth rates show a logistic sigmoidal growth trend different from those commonly observed in other patterned non-nitride III-V NWs. The sigmoidal fitting provides further insight into the PL spectral shift arising from differences in Sb and N incorporation from pitch induced variation in secondary fluxes. Results indicate that sigmoidal fitting can be a potent tool for designing patterned NW arrays of optimal pitch length for dilute nitrides and other highly mismatched alloys and heterostructures.

Corrigendum: Space charge limited conduction mechanism in GaAsSb nanowires and the effect of in-situ annealing in ultra-high vacuum (2020 Nanotechnology 31 025205).

In this work, the first observation of the space charge limited conduction mechanism (SCLC) in GaAsSb nanowires (NWs) grown by Ga-assisted molecular beam epitaxial technique, and the effect of ultrahigh vacuum in-situ annealing have been investigated. The low onset voltage of the SCLC in the NW configuration has been advantageously exploited to extract trap density and trap distribution in the bandgap of this material system, using simple temperature dependent current-voltage measurements in both the ensemble and single nanowires. In-situ annealing in an ultra-high vacuum revealed significant reduction in the trap density from 1016 cm-3 in as-grown NWs to a low level of 7 * 1014 cm-3 and confining wider trap distribution to a single trap depth at 0.12 eV. A comparison of current conduction mechanism in the respective single nanowires using conductive atomic force microscopy (C-AFM) further confirms the SCLC mechanism identified in GaAsSb ensemble device to be intrinsic. Higher current observed in current mapping by C-AFM, increased 4K photoluminescence (PL) intensity along with reduced full-width half maxima and more symmetric PL spectra, reduced asymmetrical broadening and increased TO/LO mode in room temperature Raman spectra for in-situ annealed NWs again attest to effective annihilation of traps leading to the improved optical quality of NWs compared to as-grown NWs. Hence, the I-V-T analysis of the SCLC mechanism has been demonstrated to be a simple approach to obtain information on growth induced traps in the NWs.

Space charge limited conduction mechanism in GaAsSb nanowires and the effect of in situ annealing in ultra-high vacuum.

In this work, the first observation of the space charge limited conduction mechanism (SCLC) in GaAsSb nanowires (NWs) grown by Ga-assisted molecular beam epitaxial technique, and the effect of ultra-high vacuum in situ annealing have been investigated. The low onset voltage of the SCLC in the NW configuration has been advantageously exploited to extract trap density and trap distribution in the bandgap of this material system, using simple temperature dependent current-voltage measurements in both the ensemble and single nanowires. In situ annealing in ultra-high vacuum revealed significant reduction in the trap density from 1016 cm-3 in as-grown NWs to a low level of 7 × 1014 cm-3 and confining wider trap distribution to a single trap depth at 0.12 eV. A comparison of current conduction mechanism in the respective single nanowires using conductive atomic force microscopy (C-AFM) further confirms the SCLC mechanism identified in GaAsSb ensemble device to be intrinsic. Higher current observed in current mapping by C-AFM, increased 4 K photoluminescence (PL) intensity along with reduced full-width half maxima and more symmetric PL spectra, and reduced asymmetrical broadening with increased TO/LO mode in room temperature Raman spectra for in situ annealed NWs again attest to effective annihilation of traps leading to the improved optical quality of NWs compared to as-grown NWs. Hence, the I-V-T analysis of the SCLC mechanism has been demonstrated as a simple approach to obtain information on growth induced traps in the NWs.

Molecular beam epitaxial growth of GaAsSb/GaAsSbN/GaAlAs core-multishell nanowires for near-infrared applications.

We report on the bandgap engineering of the GaAsSb/GaAsSbN heterostructured nanowires (NWs) in the core-shell architecture using the unique properties of dilute nitride material system for near-infrared photodetection. A high density of vertical GaAsSb/GaAsSb(N)/GaAlAs core-multishell configured NWs with well faceted, smooth surface morphology has been grown on Si (111) substrates using Ga-assisted molecular beam epitaxy. A low Sb content GaAsSb core has been shown to enable the coherently strained growth of dilute nitride shell with higher Sb content in GaAsSbN shell NWs. A systematic study of N and V/III beam equivalent pressure ratios is carried out to achieve the large band-gap reduction, while successfully incorporating higher Sb content in the dilute nitride shells (GaAs1-x Sb x N; x = 0.27). The incorporation of N acts to relieve strain and provide a smooth surface morphology as well as redshift the 4K photoluminescence (PL) peak energy by ∼160 meV in comparison to a non-nitride shell. The selected area diffraction pattern confirms zinc-blende structure in all the NWs and did not show any noticeable planar defects in dilute nitride NWs. We successfully, thus demonstrate GaAsSb/GaAsSbN/GaAlAs core-shell NWs by engineering the lattice strain of nitride shell with the non-nitride ternary core, for extending the 4K photoemission up to 1.43 µm.

Clostridium difficile Enteritis after Total Abdominal Colectomy for Ulcerative Colitis.

INTRODUCTION: Isolated Clostridium difficile small bowel enteritis is a rare condition with significant morbidity and mortality. PRESENTATION OF CASE: An 83-year-old female with refractory ulcerative colitis underwent a total proctocolectomy and end ileostomy. Her postoperative course was complicated with return to the operating room for repair of an incarcerated port site hernia. Subsequently, she developed septic shock and multiorgan failure requiring intubation and mechanical ventilation, renal replacement therapy, and high dose vasopressors. Diagnostic workup revealed diffuse small bowel wall thickening on computed tomography scan as well as positive nucleic acid amplification test for C. difficile toxin B gene. Despite treatment with antibiotics and maximum attempts at resuscitation, the patient expired. Discussion. C. difficile infection most commonly affects the colon but rarely can involve the small bowel. The pathogenesis of C. difficile enteritis is unclear but is believed to mirror that of colitis. Surgical patients are susceptible for C. difficile infection, as they tend to be relatively immunosuppressed in the postoperative period. Radiologic findings of enteritis may mimic those of colitis and this includes small bowel dilation and thickening. Treatment for this condition has not been well established but it is approached similar to colitis. CONCLUSION: Despite an increase in the number of case reports of C. difficile enteritis, it continues to be a rare but potentially fatal infection. Clinicians should maintain a high index of suspicion especially in patients with inflammatory bowel disease who undergo colon resections.

Epidemiology and Pathophysiology of Diverticular Disease.

Colonic diverticular disease is a common health care issue which has historically been attributed to western countries and older age population. Recent studies have shown a rise in incidence among developing countries that have adopted western diets as well as rise in prevalence among younger patients. In this article, the authors discuss the incidence, epidemiology, and pathophysiology of colonic diverticular disease.

Anorectal melanoma.

Anorectal melanoma is a disease that can be difficult to diagnose because of its unclear presentation. After diagnosis, the main treatment available is surgical resection. Sentinel lymph node mapping has an unclear role in its management. Adjuvant therapy has long been recommended; however, there are no strong data to support its use. Prognostic factors to help gauge survival are also not clear; nevertheless, there is a strong association between stage of disease and histologic perineal invasion. Anorectal melanoma is a very rare disease with a dismal prognosis.