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The objective of this review is to describe the normal and variant anatomy of the inferior mesenteric artery (IMA), including a brief overview of the relevant embryology, as well as proposing a classification system of the IMA vasculature, and clinical significance. A systematic review of articles published in Google Scholar and PubMed database using search terms: inferior mesenteric artery anatomy, inferior mesenteric artery variation, inferior mesenteric artery development, mesenteric circulation anatomy and variation, inferior mesenteric artery angiography. This was followed by review of the reference list of relevant publications to reveal publications missed during the initial search. Several standard anatomy and surgery text books were also referred for normal anatomy. The anatomy of the inferior mesenteric system is highly variant, with only a small proportion of anatomical, angiographic or surgical studies providing support for what is traditionally taught to be normal anatomy. Whilst the origin of the inferior mesenteric artery is less variant, the branching into left colic, sigmoidal and superior rectal arteries is variable between individuals in terms of origin of branches, number of branches and the presence or absence of certain branches. Whilst there did not appear to be a common classification system, similarities included three main variants of branching with a colo-sigmoid trunk, recto-sigmoid trunk or common trifurcation. There is a disparity between what is described in anatomical texts as the ‘normal’ IMA, and what is seen in anatomical, radiological and surgical research studies. The variable anatomy of the inferior mesenteric artery and its branches is significant in radiological interpretation and colorectal surgery from both an oncological perspective when considering resection, as well as in colonic ischaemia. A classification system has been introduced with a step-wise approach to the assessment of the IMA anatomy to avoid misleading nomenclature and provide a framework for surgeons to assess the vasculature.

Situs inversus is described as exact mirroring of the normal anatomical arrangement of the major visceral organs. Polysplenia is a congenital anomaly associated with situs inversus and causes various splenic abnormalities. This case discusses a 62-year-old female who presented to the emergency department with hypotension and abdominal pain. Commuted tomography reveals situs inversus and a lobulated mass in the right upper quadrant consistent with a splenic rupture intraoperatively. This is the first reported case of a spontaneous splenic rupture in a patient with situs inversus. This case highlights the rarity of splenic injuries in situs inversus and the unique anatomical challenges that surgeons are faced with intraoperatively in a high-pressure environment.

The incidence of colonic diverticulitis is increasing. In Australia the majority of diverticulitis occurs in the left colon and patients typically undergo colonoscopy following an attack. At present debate exists regarding the utility of this costly procedure and a flexible sigmoidoscopy has been proposed as a cheaper, less invasive alternative. This paper seeks to examine whether significant pathology is being detected in the right and transverse colon to warrant colonoscopy, as opposed to a flexible sigmoidoscopy. A retrospective review of colonoscopies performed between August 2016 and August 2018, indicated by diverticulitis alone, performed in a single Australian metropolitan hospital. 189 patient colonoscopies were reviewed in combination with the pathology forms. Only 1 primary colonic malignancy was detected, found in the left colon. 110 traditional adenomas and 35 sessile serrated adenomas were detected. 41.8% of patients had a polyp detected with an average of 1.9 polyps per patient. 38.6% of polyps were resected from the left colon while 61.4% were removed from the right and transverse colon. In total 30 polyps > 10 mm or with high-risk histological features were resected, 18 (60%) from the left colon and 12 (40%) from the right and transverse. 20 patients (10.6%) met the criteria for high-risk adenomas and 50% of those had > 40% of their polyps in the right and transverse colon. There was no significant difference in age between patients with polyps and those without. Despite over half the patients having no polyps and only one left sided malignancy. This study demonstrates that the right and transverse colon is responsible for over 50% of the polyps removed and similar proportion of the advanced polyps. Where endoscopic surveillance after acute colonic diverticulitis is performed, this study supports the use of colonoscopy and cautions against flexible sigmoidoscopy alone.

The nature of the surface roughness of electrolessly etched p-type Si nanowires (NWs) is examined using high resolution transmission electron microscopy and shown to comprise individual silicon nanocrystallites throughout the waviness of the roughness features. As the frequency of roughness features are believed to be sources of surface and boundary scattering, the thermal conductivity below the Casimir limit is still not fully explained. The frequency shift and development of asymmetry in the optical phonon mode in silicon was monitored by Raman scattering measurements as a function of temperature (>1000 K). We assessed the influence of Si NW roughness features on phonon scattering mechanisms including quantum confinement of phonons from roughness nanocrystals, boundary scattering, and optical phonon decay to interacting 3- and 4-phonon processes that may contribute to the cause of significant thermal conductivity suppression in rough Si nanowires. High temperature studies and detailed examination of the substrate of roughness revealed high frequency optical phonon contributions to thermal conductivity suppression.

We report intense red luminescence from mesoporous n+-Si(100) nanowires (NWs) and nanocrystal-decorated p-Si NWs fabricated using electroless metal assisted chemical (MAC) etching. n+-Si NWs are composed of a labyrinthine network of silicon nanocrystals in a random mesoporous structure. p-type Si(100) NWs exhibit solid core structure, with a surface roughness that contains surface-bound nanocrystals. Both mesoporous n+-Si NWs and rough, solid p-Si NWs exhibit red luminescence at ∼1.7 and ∼1.8 eV, respectively. Time-resolved photoluminescence (PL) measurements indicated long (tens of μs) radiative recombination lifetimes. The red luminescence is visible with the naked eye and the red light is most intense from mesoporous n+-Si NWs, which exhibit a red-shift in the emission maximum to 1.76 eV at 100 K. The red PL from monolithic arrays of p-type NWs with nanocrystal-decorated rough surfaces is comparatively weak, but originates from the surface bound nanocrystals. Significant PL intensity increase is found during excitation for mesoporous NWs. X-ray photoelectron spectroscopy identifies a stoichiometric SiO2 on the rough p-Si NWs with a SiOx species at the NW surface. No distinct oxide is found on the mesoporous NWs. The analysis confirms that long life-time PL emission arises from quantum confinement from internal nanoscale crystallites, and oxidized surface-bound crystallites, on n+- and p-Si NWs respectively.

This review outlines the developments and recent progress in metal-assisted chemical etching of silicon, summarizing a variety of fundamental and innovative processes and etching methods that form a wide range of nanoscale silicon structures. The use of silicon as an anode for Li-ion batteries is also reviewed, where factors such as film thickness, doping, alloying, and their response to reversible lithiation processes are summarized and discussed with respect to battery cell performance. Recent advances in improving the performance of silicon-based anodes in Li-ion batteries are also discussed. The use of a variety of nanostructured silicon structures formed by many different methods as Li-ion battery anodes is outlined, focusing in particular on the influence of mass loading, core-shell structure, conductive additives, and other parameters. The influence of porosity, dopant type, and doping level on the electrochemical response and cell performance of the silicon anodes are detailed based on recent findings. Perspectives on the future of silicon and related materials, and their compositional and structural modifications for energy storage via several electrochemical mechanisms, are also provided.

Diverticular disease and its spectrum of complications are increasingly encountered in the Australian population. Accurate management of patients before and after an acute episode entails extension beyond the acute event to include dietary advice and colonoscopy.The objectives of this article are to evaluate the literature regarding dietary factors and diverticular disease, routine colonoscopy and antibiotic treatment in acute diverticulitis, to enable primary care physicians to manage patients and provide sound advice after hospital admission.Diverticulitis can often be managed in the community by general practitioners, but the necessity of antibiotics may not be definitive. When patients do require hospital admission, advice and management of patient lifestyle factors after admission, and investigations to rule out red flags are crucial. These elements of patient management are the subject of debate, as it appears that standard dietary advice does not alter a patient's clinical course, and colonoscopy is not always necessary and should be used judiciously.

The Li+ insertion and extraction characteristics at n-type and p-type Si(100) electrodes with different carrier density and doping type are investigated by cyclic voltammetry and constant current measurements. The insertion and extraction potentials are demonstrated to vary with cycling and the occurrence of an activation effect is shown in n-type electrodes where the charge capacity and voltammetric currents are found to be much higher than p-type electrodes. A rate-dependent redox process influenced by the surface region electronic density, which influences the magnitude of cyclic voltammetry current is found at Si(100) surface regions during Li insertion and extraction. At p-type Si(100) surface regions, a thin, uniform film forms at lower currents, while also showing a consistently high (>70%) Coulombic efficiency for Li extraction. The p-type Si(100) surface region does not undergo crack formation after deintercalation and the amorphization was demonstrated using transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) and Raman scattering demonstrate that highly doped n-type Si(100) retains Li as a silicide and converts to an amorphous phase as a two-step phase conversion process. The findings show the succinct dependence of Li insertion and extraction processes for uniformly doped Si(100) single crystals and how the doping type and its effect on the semiconductor-solution interface dominate Li insertion and extraction, composition, crystallinity changes and charge capacity.

Porous semiconductors structured top-down by electrochemical means, and from bottom-up growth of arrays and arrangements of nanoscale structures, are shown to be amenable to a range of useful thermal, optical, electrical and electrochemical properties. This paper summarises recent investigations of the electrochemical, electrical, optical, thermal and structural properties of porous semiconductors such as Si, In2O3, SnO2 and ITO, and dispersions, arrays and arrangements of nanoscale structures of each of these materials. We summarize the property-inspired application of such structurally engineered arrangements and morphologies of these materials for antireflection coatings, broadband absorbers, transparent contacts to LEDs that improve transmission, electrical contact and external quantum efficiency. Additionally the possibility of thermoelectric performance through structure-mediated variation in thermal resistance and phonon scattering without a p-n junction is shown through phonon engineering in roughened nanowires. Lastly, we show that bulk crystals and nanowires of p- and n-type doped Si are promising for use as anodes in Li-ion batteries.

Silicon nanowires were fabricated by a metal assisted chemical (MAC) etching process and routes toward ohmic contacting of substrates for Li-ion battery anode application were developed. Si nanowire layers are comprised of wires that are single crystal with rough outer surfaces. The nanowires are epitaxial with the underlying Si(100) substrate, maintain equivalent doping density and crystal orientation, and are coated with a stoichiometric SiO2. Electrical backside contacting using an In-Ga eutectic allows low-resistance ohmic contacts to low-doped nanowire electrodes for electrochemical testing.

We have shown that SiNWs formed on (100) Si substrates by metal-assisted chemical etching can exhibit different Raman scattering processes that are dependent on the orientation of examined NWs to the incident excitation light. The SiNWs retain the single crystal orientation and doping from the original bulk substrate and form as rough and mesoporous NWs with a SiOx shell surrounding the NW. The Raman scattering spectra of vertical and horizontally lying SiNWs showed quantum confined phonon scattering processes from narrow and roughened NWs, whose spectral resolution was increased by orienting NW horizontal to the beam to maximize probe cross-section. SiOx contributions were not evident and specific substrate Raman modes were suppressed for horizontal NWs. Beam induced heating to 425 K showed pronounced red-shifting and asymmetry of the TO, 2TO and 2TA phonon modes consistent with phonon quantum confinement effects not observable when the NW were parallel to incident excitation.

peer-reviewed By using Si(100) with different dopant type (n(++)-type (As) or p-type (B)), we show how metal-assisted chemically etched (MACE) nanowires (NWs) can form with rough outer surfaces around a solid NW core for p-type NWs, and a unique, defined mesoporous structure for highly doped n-type NWs. We used high resolution electron microscopy techniques to define the characteristic roughening and mesoporous structure within the NWs and how such structures can form due to a judicious choice of carrier concentration and dopant type. The n-type NWs have a mesoporosity that is defined by equidistant pores in all directions, and the inter-pore distance is correlated to the effective depletion region width at the reduction potential of the catalyst at the silicon surface in a HF electrolyte. Clumping in n-type MACE Si NWs is also shown to be characteristic of mesoporous NWs when etched as high density NW layers, due to low rigidity (high porosity). Electrical transport investigations show that the etched nanowires exhibit tunable conductance changes, where the largest resistance increase is found for highly mesoporous n-type Si NWs, in spite of their very high electronic carrier concentration. This understanding can be adapted to any low-dimensional semiconducting system capable of selective etching through electroless, and possibly electrochemical, means. The process points to a method of multiscale nanostructuring NWs, from surface roughening of NWs with controllable lengths to defined mesoporosity formation, and may be applicable to applications where high surface area, electrical connectivity, tunable surface structure, and internal porosity are required. (C) 2013 AIP Publishing LLC. PUBLISHED peer-reviewed

Recent advancements in the growth and formation of semiconducting nanostructures, particularly group 14 metalloid semiconductors such as silicon and germanium have shown how quantum effects can be engineered and controlled (1,2) to modify thermal and optical properties (3). In particular, the nanostructuring of silicon materials mediates phonon scattering and confinement, including reduction of thermal conductivity (4,5) and Si-based nanowire heterostructures have been employed as solar cell materials and nanoelectronic power sources. Crystal sizes below the Bohr radius also results in light emission, and effective bandgap modification can influence absorbed thermopower in nanoscale silicon, and for photovoltaics. We report intense red luminescence from mesoporous n+-Si(100) nanowires (NWs) and nanocrystal-decorated p-Si NWs fabricated using electroless metal assisted chemical (MAC) etching (6-9). n+-Si NWs are composed of a labyrinthine network of silicon nanocrystals in a random mesoporous structure. p-type Si(100) NWs exhibit solid core structure, with a surface roughness that contains surface-bound nanocrystals. Both mesoporous n+-Si NWs and rough, solid p-Si NWs exhibit red luminescence at ~1.7 and ~1.8 eV, respectively. Time-resolved photoluminescence (PL) measurements indicated long (tens of µs) radiative recombination lifetimes. The red luminescence is visible with the naked eye and the red light is most intense from mesoporous n+-Si NWs, which exhibit a red-shift in the emission maximum to 1.76 eV at 100 K. The red PL from monolithic arrays of p-type NWs with nanocrystal-decorated rough surfaces is comparatively weak, but originates from the surface bound nanocrystals. Significant PL intensity increase is found during excitation for mesoporous NWs. X-ray photoelectron spectroscopy identifies a stoichiometric SiO2 on the rough p-Si NWs with a SiOx species at the NW surface. No distinct oxide is found on the mesoporous NWs. The analysis confirms that long life-time PL emission arises from quantum confinement from internal nanoscale crystallites, and oxidized surface-bound crystallites, on n+- and p-Si NWs respectively. References (1) G. S. Armatas and M. G. Kanatzidis, Science, 313, 817 (2006). (2) B. Kiraly, S. Yang and T. J. Huang, Nanotechnology, 24, 245704 (2013) (3) L. T. Canham, Appl. Phys. Lett., 57, 1046 (1990). (4) A. I. Hochbaum, R. Chen, R. D. Delgado, W. Liang, E. C. Garnett, M. Najarian, A. Majumdar and P. Yang, Nature, 451, 163 (2008). (5) A. I. Boukai, Y. Bunimovich, J. Tahir-Kheli, J.-K. Yu, W. A. Goddard Iii and J. R. Heath, Nature, 451, 168 (2008). (6) C. O'Dwyer, W. McSweeney and G. Collins, ECS J. Solid State Sci. Technol., 5, R3059 (2016). (7) W. McSweeney, H. Geaney and C. O'Dwyer, Nano Res., 8, 1395 (2015). (8) W. McSweeney, C. Glynn, H. Geaney, G. Collins, J. D. Holmes and C. O'Dwyer, Semicon. Sci. Technol., 31, 014003 (2015). (9) E. G. Chadwick, V. Mogili, C. O’Dwyer, J. Moore, J. Fletcher, F. Laffir, G. Armstrong and D. A. Tanner, RSC Adv., 3, 19393 (2013).

Si nanowires (NWs) are shown to develop internal mesoporosity during metal assisted chemical etching from Si wafers. The onset of internal porosity in n+-Si(100) compared to p-Si(100) is examined through a systematic investigation of etching parameters (etching time, AgNO3 concentration, HF % and temperature). Electron microscopy and Raman scattering show that specific etching conditions reduce the size of the internal Si nanocrystallites in the internal mesoporous structure to 3–5 nm. Mesoporous NWs are found to have diameters as large as 500 nm, compared to ~100 nm for p-NWs that develop surface roughness. Etching of Si (100) wafers results in (100)-oriented NWs forming a three-fold symmetrical surface texture, without internal NW mesoporosity. The vertical etching rate is shown to depend on carrier concentration and degree of internal mesoporosity formation. Raman scattering of the transverse optical phonon and photoluminescence measurements confirm quantum size effects, phonon scattering and visible intense red light emission between 685 and 720 nm in internally mesoporous NWs associated with the etching conditions. Laser power heating of NWs confirms phonon confinement and scattering, which is demonstrated to be a function of the internal mesoporosity development. We also demonstrate the limitation of mesoporosity formation in n+-Si NWs and development of porosity within p-Si NWs by controlling the etching conditions. Lastly, the data confirm that phonon confinement and scattering often reported for Si NWs is due to surface-bound and internal nanostructure, rather than simply a diameter reduction in NW materials.

Current lithium-ion battery anode research involves significant investigations of semiconducting materials, particularly Si as its theoretical specific capacity is >4000 mAh/g1. Previous theoretical studies showed that porous Si with a large pore size and high porosity can maintain its structure after Li ion induced alloying and swelling. Metal-assisted chemical (MAC) etching is shown here to form internally mesoporous nanowires in the form of a layer, etched from highly doped Si2-4. Some porous materials are well known to exhibit pseudocapacitive behaviour in aqueous electrolytes5,6. Maintaining the structure without stress-induced cracked caused by volumetric changes in material is crucial in achieving a high capacity and long cycle retention. Almost all investigations of nanoscale Si involve their deposition onto a metallic current collector electrode within the battery cell. Here, we demonstrate that pseudocapacitive behaviour can be harnessed when Si nanowires are etched to maximum mesoporosity, forming an electrically dead layer on silicon current collector electrodes. This limits insertion or alloying processes to form Li-Si phases7and charge is stored within the electric double layer, even in Li-ion containing electrolytes. Measurements using cyclic and linear voltammetry supported by Raman scattering spectroscopy and electron microscopy confirm surface charge storage mechanisms; pseudocapacitance is not observed when the same nanowires are used on stainless steel current collectors. In such cases, the rate of lithiation is shown to be related to the degree of porosity and the net surface electronic density of the porous silicon in accumulation mode during charging. References C. K. Chan, H. Peng, G. Liu, K. McIlwrath, X. F. Zhang, R. A. Huggins and Y. Cui, Nat. Nanotechnol. 3, 31 (2008). W. McSweeney, O. Lotty, N. Mogili, C. Glynn, H. Geaney, D. Tanner, J. Holmes and C. O'Dwyer, J. Appl. Phys. 114,034309 (2013). A. I. Hochbaum, D. Gargas, Y. J. Hwang, P. Yang, Nano Lett. 9, 3550 (2009). W. McSweeney, O. Lotty, J. D. Holmes and C. O'Dwyer, ECS Trans., 35, 25 (2011). P. Simon and Y. Gogotsi, Nat. Mater. 7, 845 (2008). T. Brezesinski, J. Wang, S. H. Tolbert and B. Dunn, Nat. Mater. 9, 146 (2010). W. McSweeney, O. Lotty, C. Glynn, H. Geaney, J. D. Holmes and C. O'Dwyer, Electrochim. Acta, 135, 356 (2014).

Silicon nanostructures and methods to grow them and influence their structure and morphology has recently been demonstrated to offering a useful strategy to control thermal conductivity and light-matter interactions. The transport and scattering of phonons in Si has demonstrated effective thermoelectric performance largely due to effects caused by surface roughening and nanoscale irregularities in the crystal structure that contribute to diffuse boundary scattering mechanisms. When confinement effects are introduced in crystalline materials the electron and phonon transport can be significantly due to three discrete effects: increased boundary scattering, changes in phonon dispersion, and quantization of phonon transport. Using both room-temperature and in-situ thermal Raman scattering spectroscopy the transport of phonons within Si and its nanostructures can be probed quickly and with little sample preparation. Both ambient and high temperature characteristics of the Si are examined and phonon transport changes between the b-Si and the SiNWs can be linked to scattering effects due to the different morphologies possible using metal-assisted chemical etching to form NWs with tunable porosity and surface roughness. This work demonstrates that by increasing the number of available scattering sites in nanostructured Si within the structure (not just boundary scattering at rough surfaces), the role of four phonon processes on the phonon transport within Si can be optimised. This study is important for providing information on the phonon transport within Si and its nanostructures allowing morphologies that affect phonon transport to be exploited for engineering the thermoelectric properties of future Si devices. References J. Lim, K. Hippalgaonkar, S. C. Andrews, A. Majumdar, P. Yang, Nano Letters, 12, 2475 (2012). J. Tang, H.-T. Wang, D. H. Lee, M. Fardy, Z. Huo, T. P. Russell, P. Yang, Nano Letters, 10, 4279 (2010). A. I. Hochbaum, R. Chen, R.D. Delgado, W. Liang, E. C. Garnett, M. Najarian, A. Majumdar, P. Yang, Nature, 451, 163 (2008). A. I. Boukai, Y. Bunimovich, J. Tahir-Kheli, J. K. Yu, W. A. Goddard, J. R. Heath, Nature, 451, 168 (2008). K. Q. Peng, J. J. Hu, Y. J. Yan, Y. Wu, H. Fang, Y. Xu, S. T. Lee, J. Zhu, Advanced Functional Materials, 16, 387 (2005).

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