Studies on adsorption, reaction mechanisms and kinetics for photocatalytic degradation of CHD, a pharmaceutical waste.

The photocatalytic degradation of chlorhexidine digluconate (CHD), a disinfectant and topical antiseptic and adsorption of CHD catalyst surface in dark condition has been studied. Moreover, the value of kinetic parameters has been measured and the effect of adsorption on photocatalysis has been investigated here. Substantial removal was observed during the photocatalysis process, whereas 40% removal was possible through the adsorption route on TiO2 surface. The parametric variation has shown that alkaline pH, ambient temperature, low initial substrate concentration, high TiO2 loading were favourable, though at a certain concentration of TiO2 loading, photocatalytic degradation efficiency was found to be maximum. The adsorption study has shown good confirmation with Langmuir isotherm and during the reaction at initial stage, it followed pseudo-first-order reaction, after that Langmuir Hinshelwood model was found to be appropriate in describing the system. The present study also confirmed that there is a significant effect of adsorption on photocatalytic degradation. The possible mechanism for adsorption and photocatalysis has been shown here and process controlling step has been identified. The influences of pH and temperature have been explained with the help of surface charge distribution of reacting particles and thermodynamic point of view respectively.

Photocatalytic degradation of pharmaceutical wastes by alginate supported TiO2 nanoparticles in packed bed photo reactor (PBPR).

In recent years deposal of pharmaceutical wastes has become a major problem globally. Therefore, it is necessary to removes pharmaceutical waste from the municipal as well as industrial effluents before its discharge. The convectional wastewater and biological treatments are generally failed to separate different drugs from wastewater streams. Thus, heterogeneous photocatalysis process becomes lucrative method for reduction of detrimental effects of pharmaceutical compounds. The main disadvantage of the process is the reuse or recycle of photocatalysis is a tedious job. In this work, the degradation of aqueous solution of chlorhexidine digluconate (CHD), an antibiotic drug, by heterogeneous photocatalysis was study using supported TiO2 nanoparticle. The major concern of this study is to bring down the limitations of suspension mode heterogeneous photocatalysis by implementation of immobilized TiO2 with help of calcium alginate beads. The alginate supported catalyst beads was characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDAX) as well as the characteristic crystalline forms of TiO2 nanoparticle was confirmed by XRD. The degradation efficiency of TiO2 impregnated alginate beads (TIAB) was compared with the performance of free TiO2 suspension. Although, the degradation efficiency was reduced considerably using TIAB but the recycle and reuse of catalyst was increased quite appreciably. The kinetic parameters related to this work have also been measure. Moreover, to study the susceptibility of the present system photocatalysis of other three drugs ibuprofen (IBP), atenolol (ATL) and carbamazepine (CBZ) has been carried out using immobilized TiO2. The continuous mode operation in PBPR has ensured the applicability of alginate beads along with TiO2 in wastewater treatment. The variation of residence time has significant impact on the performance of PBPR.

Development of a mathematical model to predict different parameters during pharmaceutical wastewater treatment using TiO2 coated membrane.

The aim of present study is to develop a mathematical model to understand the photomineralization process for an antiseptic drug component, chlorhexidine digluconate using catalytic membrane. Overall process was executed in a photo reactor with immobilized TiO2 nanoparticles on the membrane surface, which gives the better recovery and reuse of the catalyst. To assess the overall process performance, a mathematical model has been developed for prediction of substrate concentration in the permeate stream and the theoretical build-up of the polarized layer in case of a membrane coated with TiO2 nanoparticles. In the developed mathematical model, the governing partial differential equation was solved with the help of initial boundary condition over the concentration boundary layer and Kozeny-Carmen equation. In this model the simultaneous change in the active surface area and the polarized layer thickness with the change in substrate concentration in the boundary layer was incorporated to enhance the accuracy of the model. The resulting non-linear partial differential equation, coupled with other non-linear ordinary differential equation is solved using Runga Kutta fourth order method. Average deviation between theoretical results and the experimental data generated in this study was found to remain within ±5% and precision level was maintained at 0.01%.

Effect of atomic interconnects on percolation in single-walled carbon nanotube thin film networks.

The formation of covalent bonds to single-walled carbon nanotube (SWNT) or graphene surfaces usually leads to a decrease in the electrical conductivity and mobility as a result of the structural rehybridization of the functionalized carbon atoms from sp(2) to sp(3). In the present study, we explore the effect of metal deposition on semiconducting (SC-) and metallic (MT-) SWNT thin films in the vicinity of the percolation threshold and we are able to clearly delineate the effects of weak physisorption, ionic chemisorption with charge transfer, and covalent hexahapto (η(6)) chemisorption on these percolating networks. The results support the idea that for those metals capable of forming bis-hexahapto-bonds, the generation of covalent (η(6)-SWNT)M(η(6)-SWNT) interconnects provides a conducting pathway in the SWNT films and establishes the transition metal bis-hexahapto organometallic bond as an electronically conjugating linkage between graphene surfaces.

Effect of covalent chemistry on the electronic structure and properties of carbon nanotubes and graphene.

In this Account, we discuss the chemistry of graphitic materials with particular reference to three reactions studied by our research group: (1) aryl radical addition, from diazonium precursors, (2) Diels-Alder pericyclic reactions, and (3) organometallic complexation with transition metals. We provide a unified treatment of these reactions in terms of the degenerate valence and conduction bands of graphene at the Dirac point and the relationship of their orbital coefficients to the HOMO and LUMO of benzene and to the Clar structures of graphene. In the case of the aryl radical addition and the Diels-Alder reactions, there is full rehybridization of the derivatized carbon atoms in graphene from sp(2) to sp(3), which removes these carbon atoms from conjugation and from the electronic band structure of graphene (referred to as destructive rehybridization). The radical addition process requires an electron transfer step followed by the formation of a σ-bond and the creation of a π-radical in the graphene lattice, and thus, there is the potential for unequal degrees of functionalization in the A and B sublattices and the possibility of ferromagnetism and superparamagnetism in the reaction products. With regard to metal functionalization, we distinguish four limiting cases: (a) weak physisorption, (b) ionic chemisorption, in which there is charge transfer to the graphitic structure and preservation of the conjugation and band structure, (c) covalent chemisorption, in which there is strong rehybridization of the graphitic band structure, and (d) covalent chemisorption with formation of an organometallic hexahapto-metal bond that largely preserves the graphitic band structure (constructive rehybridization). The constructive rehybridization that accompanies the formation of bis-hexahapto-metal bonds, such as those in (η(6)-SWNT)Cr(η(6)-SWNT), interconnects adjacent graphitic surfaces and significantly reduces the internanotube junction resistance in single-walled carbon nanotube (SWNT) networks. The conversion of sp(2) hybridized carbon atoms to sp(3) can introduce a band gap into graphene, influence the electronic scattering, and create dielectric regions in a graphene wafer. However, the organometallic hexahapto (η(6)) functionalization of the two-dimensional (2D) graphene π-surface with transition metals provides a new way to modify graphitic structures that does not saturate the functionalized carbon atoms and, by preserving their structural integrity, maintains the delocalization in these extended periodic π-electron systems and offers the possibility of three-dimensional (3D) interconnections between adjacent graphene sheets. These structures may find applications in interconnects, 3D-electronics, organometallic catalysis, atomic spintronics and in the fabrication of new electronic materials.

Chemistry at the Dirac point: Diels-Alder reactivity of graphene.

Most of the interesting physics of graphene results from the singular electronic band structure at the so-called Dirac point, where the conduction and valence bands cross in momentum space. Although graphene is very stable thermodynamically, the electronic structure at the Dirac point facilitates basal plane chemistry including pericyclic reactions such as the Diels-Alder reaction. We have discovered a series of facile Diels-Alder reactions in which graphene can function either as a diene when paired with tetracyanoethylene and maleic anhydride or as a dienophile when paired with 2,3-dimethoxybutadiene and 9-methylanthracene. In this Account, we seek to rationalize these findings using simple arguments based on considerations of orbital symmetry and the frontier molecular orbital theory. The graphene conduction and valence bands (HOMO and LUMO) cross at the Dirac point, which defines the work function (W = 4.6 eV). Thus, the HOMO and LUMO form a degenerate pair of orbitals at this point in momentum space with the same ionization potential (IP) and electron affinity (EA). Based on the importance of the energies of the HOMO (-IP) and LUMO (-EA) in frontier molecular orbital (FMO) theory, graphene should be a reactive partner in Diels-Alder reactions due to the very high-lying HOMO and low-lying LUMO (energies of -4.6 eV). Inspection of the orbital symmetries of the degenerate pair of half-occupied band orbitals at the Dirac point confirms that with the appropriate orbital occupancies, both diene and dienophile reaction partners should undergo concerted Diels-Alder reactions with graphene that are allowed based on the Woodward-Hoffmann principles of orbital symmetry.

A new distinguishing attack on reduced round ChaCha permutation.

This work concentrates on differential-linear distinguishing attacks on the prominent ARX-based permutation ChaCha. Here, we significantly improve the 7-round differential-linear distinguisher for ChaCha permutation by introducing a new path of linear approximation. We first introduce a new single-bit differential distinguisher for the 3.5th round of the permutation that assists us in inventing a new path for the differential-linear distinguisher. We show that one can distinguish a 7-round ChaCha permutation with time complexity of [Formula: see text]. This improves the recent work of Coutinho et al. (in: Advances in Cryptology-ASIACRYPT 2022-28nd International Conference on the Theory and Application of Cryptology and Information Security, Taipei, Taiwan, December 5-9, 2012, Springer, 2022), which achieved time complexity [Formula: see text]. We also propose a distinguisher for the 7.25-round of ChaCha permutation and this is the first distinguishing attack for more than 7-round of ChaCha permutation. We provide theoretical proofs and the corresponding experimental results for the linear approximations that we use for differential-linear distinguisher. We point out that the existing multibit distinguishing attacks on the cipher ChaCha are invalid. These attacks are worked only for the ChaCha permutation.

Reversible grafting of α-naphthylmethyl radicals to epitaxial graphene.

The Kolbe electrochemical oxidation strategy has been utilized to achieve an efficient quasireversible electrochemical grafting of the α-naphthylmethyl functional group to graphene. The method facilitates reversible bandgap engineering in graphene and preparation of electrochemically erasable organic dielectric films. The picture shows Raman D-band maps of both systems.

Weak-keys and key-recovery attack for [Formula: see text].

In this paper, we study NIST lightweight 3rd round candidate [Formula: see text]. The core component of [Formula: see text] is the keyed permutation [Formula: see text], which is based on a non-linear feedback shift register. By analysing this permutation carefully, we are able to find good cubes that are used to build distinguishers in the weak-key setting. In particular, we show that there are at least [Formula: see text] keys for which TinyJAMBU can be distinguished from a random source for up to 476 rounds. These distinguishers outperform the best-known distinguishers, which were proposed in 'Scientific Reports - Nature' by Teng et al. We are the first to study the exact degree of the feedback polynomial [Formula: see text] in the nonce variables. This helped us in concluding that [Formula: see text] with more than 445 rounds is secure against distinguishers using 32 sized cubes in the normal setting. Finally, we give new key-recovery attacks against [Formula: see text] using the concepts of monomial trail presented by Hu et al. at ASIACRYPT 2020. Our attacks are unlikely to jeopardise the security of the entire 640 rounds [Formula: see text], but we strongly anticipate that they will shed new lights on the cipher's security.

Diels-Alder chemistry of graphite and graphene: graphene as diene and dienophile.

The zero-band-gap electronic structure of graphene enables it to function as either the diene or the dienophile in the Diels-Alder reaction, and this versatile synthetic method offers a powerful strategy for the reversible modification of the electronic properties of graphene under very mild conditions.

A spirocyclohexyl nitroxide amino acid spin label for pulsed EPR spectroscopy distance measurements.

Site-directed spin labeling and EPR spectroscopy offer accurate, sensitive tools for the characterization of structure and function of macromolecules and their assemblies. A new rigid spin label, spirocyclohexyl nitroxide alpha-amino acid and its N-(9-fluorenylmethoxycarbonyl) derivative, have been synthesized, which exhibit slow enough spin-echo dephasing to permit accurate distance measurements by pulsed EPR spectroscopy at temperatures up to 125 K in 1:1 water/glycerol and at higher temperatures in matrices with higher glass transition temperatures. Distance measurements in the liquid nitrogen temperature range are less expensive than those that require liquid helium, which will greatly facilitate applications of pulsed EPR spectroscopy to the study of structure and conformation of peptides and proteins.

Hydrocele of the Canal of Nuck (Female Hydrocele): A Rare Differential for Inguino-Labial Swelling.

The inguinal canal is traversed by the spermatic cord in men and the round ligament of uterus in women. The round ligament is attached to the uterine cornu near the origin of fallopian tube at one end and to the ipsilateral labia majora at the other. The round ligament accompanies a pouch of parietal peritoneum in the inguinal canal, which is known as 'canal of nuck'. It is analogous to the processus vaginalis in males. Incomplete obliteration of the peritoneal pouch causes indirect inguinal hernia or hydrocele of the canal of nuck; a very rare condition in women. As these types of cases are rarely seen in surgical practice we present a case of such little-known developmental disorder in a three-year-old girl. She presented with irreducible, tender right inguino-labial swelling with tachycardia simulating incarcerated inguinal hernia, which necessitates emergency surgical exploration. On exploration it was found to be an encysted hydrocele of canal of nuck; so although rare, this entity should be considered in differential diagnosis in a female child presented with inguino-labial swelling.

Rhinosporidiosis of Parotid Duct Presenting as Consecutive Bilateral Facial Swelling: A Rare Case Report and Literature Review.

Rhinosporidiosis is a chronic granulomatous infection caused by Rhinosporidium seeberi. Sporadic cases of rhinosporidiosis has been reported from many countries but is endemic in Southern India (Madurai, Ramnad, Rajapalayam and Sivaganga), Nepal, Bangladesh and Sri Lanka. This disease commonly affects the mucous membrane of the nose or naso-pharynx and presents as a leafy, polypoidal mass. The reported extranasal sites include the oro-pharynx, eye, ear, larynx, trachea, bronchi, skin and genital mucosa. It may also become disseminated to present as a generalized form. In our case a 40-year-old female from rural West Bengal (Eastern India) presented with right sided facial swelling. Our provisional diagnosis was parotid duct cyst on the basis of careful history, scrupulous clinical examination and relevant investigations comprising CECT scan of face. Although Rhinosporidiosis was not taken into consideration in the clinical differential diagnosis, it was eventually diagnosed postoperatively by histopathological examination of surgical specimen. Two months later in follow-up, the same patient presented to us with left sided facial swelling. We managed the left facial swelling successfully with minimally invasive surgery and 100mg twice daily dapsone for 6 months. We present this case firstly because Rhinosporidiosis of parotid duct (stensen's duct) is a rare entity and secondly non-neoplastic cysts of the salivary glands are also uncommon and represent only 2-5% of all salivary gland lesions. Furthermore our case emphasizes that the clinicians should aware of this rare clinical entity specially in endemic areas, because minimally invasive techniques and medications might solve the problem while helping patients to avoid surgical excision.

Acute Urinary Retention due to Primary Pelvic Hydatid Cyst: A Rare Case Report and Literature Review.

Causes of urinary retention in old men include benign prostatic hyperplasia, prostatitis, prostate cancer, Scarring of the urethra or bladder neck as a result of injury or surgery, use of certain medicines particularly NSAIDs and opioid analgesics, constipation and neurogenic bladder. When the above common causes are not quite obvious by clinical examination and relevant investigations, then it is necessary to think of other rare diseases. It is with the above in our mind that a case of bladder outflow obstruction due to a large primary retrovesical hydatid cyst is herein reported in a 58-year-old man. Ultrasonography (USG) and Contrast Enhanced Computed Tomography (CECT) scan of the abdomen and pelvis of the patient revealed a large, multilocular, nonenhancing, cystic lesion in the rectovesical pouch having typical cartwheel appearance without any other intraabdominal organ involvement. These typical radiological characteristics led us to suspect the presence of a hydatid cyst. He underwent exploratory laparotomy where cystopericycstectomy was done. Pre-operative and post-operative albendazole prophylaxis was also given. In conclusion, hydatid cyst should always be considered in the differential diagnosis of pelvic cystic masses, specially in endemic regions.

Correlation between cyclin D1 expression and standard clinicopathological variables in invasive breast cancer in Eastern India.

INTRODUCTION: Breast cancer is the leading oncogenic threat in South-East Asian women showing an inexplicable biological aggressiveness. High expression of cyclin D1, a key molecule in breast cancer pathogenesis, has been shown by previous studies in the Western world to be associated with favorable tumoral characteristics. Apart from determining the correlation between cyclin D1 expression and standard clinicopathological variables in invasive breast cancer in Eastern India, questions that we aimed to answer through this study included: Is there a significant regional difference in expression patterns of this protein? And if yes, can it possibly account for the epidemiological differences in breast cancer occurrence and biological behavior? Finally, is testing for overexpression of this protein in regions with limited resources beneficial? MATERIALS AND METHODS: The present study was carried out on 110 previously untreated, female patients with primary breast carcinoma. Cyclin D1 expression was determined by immunohistochemistry using specific anti-cyclin D1 monoclonal antibodies. RESULTS: Overexpression of cyclin Dl was found in 78 of 110 cases (70.9%). High expression of cyclin D1 showed a significant negative correlation with tumor size (P = 0.023) and tumor grade (P = 0.045). Estrogen receptor and progesterone receptor positive cases showed a significantly positive correlation with cyclin D1 overexpression (P = 0.026 and 0.046, respectively). Interestingly, cyclin D1 positivity showed a strong correlation with the type of surgical procedure performed (P = 0.002). CONCLUSION: Cyclin D1 overexpression in breast cancer is associated with less aggressive tumoral characteristics. Furthermore, its potential epidemiological role and utility as a prognostic marker have been discussed.

An Unusual Transorbital Penetrating Injury by House-key (lock): A Case Report with a Small Review of Literature.

Penetrating injuries of the brain are quite uncommon, comprising approximately 0.4% of all head injuries. In our case, a four-year-old boy who fell forward on a house-key (lock) accidentally while playing with some other children sustained a left sided penetrating transorbital brain injury. After hospital admission, the patient had a Glasgow Coma Scale (GCS) score of 15/15, no visual loss but restriction of upward gaze (left eye) and profuse bleeding from the wound site. Firstly, the metallic key was removed in emergency operation theatre and haemostasis secured. Next day we did a combined surgical approach with neurosurgeons, Eye-surgeons and general surgeons after having CT scan report. We report this case because penetrating head injury is rare and transorbital penetrating head injury is even rarer and a predicament in emergency surgical practice with controversial management.

Hexahapto-lanthanide interconnects between the conjugated surfaces of single-walled carbon nanotubes.

We report the response of the electrical conductivity of semiconducting single-walled carbon nanotube (SWNT) thin films on exposure to metal vapors of the early lanthanides under high vacuum conditions. We attribute the strongly enhanced conductivities observed on deposition of samarium and europium to charge transfer from the metals to the SWNT backbone, thereby leading to the first examples of mixed covalent-ionic bis-hexahapto bonds [(η(6)-SWNT)M(η(6)-SWNT), where M = Sm, Eu].