Synthesis of unsymmetric phosphorotrithioates by sequential coupling of 1,1-dichloro-N,N-diethylphosphanamine with thiols and sulfenyl chloride.

Herein, we present the first, one-step, direct synthesis of unsymmetric phosphorotrithioates through a process involving sequential coupling of 1,1-dichloro-N,N-diethylphosphanamine with thiols and sulfenyl chloride. This method showcases excellent functional group tolerance, substrate compatibility, and mild reaction conditions, offering a streamlined approach for the challenging phosphorotrithioate synthesis. Additionally, the applicability of this method can be extended to the synthesis of mixed phosphoroselenodithioates.

Synthesis of mixed phosphorotrithioates via thiol coupling with bis(diisopropylamino)chlorophosphine and sulphenyl chloride.

In this study, we report a novel and efficient one-pot synthesis of mixed phosphorotrithioates under mild conditions at ambient temperature, obviating the requirement for supplementary additives. The method's versatility stems from its utilization of diverse thiols as nucleophilic reactants, 1-chloro-N,N,N',N'-tetraisopropylphosphanediamine [bis(diisopropylamino)chlorophosphine] as the phosphorus precursor, and various sulphenyl chlorides as sources of electrophilic sulfur. Notably, our investigation extends beyond mixed phosphorotrithioates to encompass the synthesis of phosphoroselenodithioates, underscoring the broad applicability of this synthetic protocol.

Association of vitamin D deficiency and vitamin D receptor (VDR) gene single-nucleotide polymorphism (rs7975232) with risk of preeclampsia.

BACKGROUND: Preeclampsia has a multifactorial-yet-elusive etiology. Recent reports suggest a link between preeclampsia and vitamin D (VD) metabolic axis. Genetic variations like single-nucleotide polymorphisms (SNPs) of vitamin D receptor (VDR) gene can alter the metabolic role of VD, which have been shown by several genetic association studies. However, there is discordance among these studies. OBJECTIVE: The current study aimed to investigate the association of VDR gene polymorphism (ApaI) and VD deficiency with risk of developing preeclampsia. PATIENTS AND METHOD: In this case-control study, 40 preeclamptic and 40 normotensive pregnant women were compared for VD status and VDR gene polymorphism. Serum 25-hydroxyvitamin-D [25(OH) D] level was determined by enzyme-linked immunosorbent assay (ELISA) and VDR gene polymorphism Apa1 was analyzed by Allele specific polymerase chain reaction (AS-PCR) using sequence specific primers. RESULTS: Serum levels of 25(OH) D were very low but comparable in both preeclamptic and normotensive pregnant women. The difference between the two groups were not statistically significant (p = .423). VDR gene polymorphism ApaI (rs7975232) was found not to have significant association with the risk of developing preeclampsia. The frequencies of wild genotype (GG) in preeclamptic and normotensive women were 27.5% and 22.5% respectively. A total of 25% of preeclamptic women had mutant homozygous genotype (TT) and 17.5% of normotensive women had mutant homozygous genotype. The frequency of mutant heterozygous genotype (GT) in preeclamptic patients was 47.5% and in normotensive women was 60%. The variation of wild and mutant genotypes between the two groups was not statistically significant (p > .05). CONCLUSION: This study showed that VDR gene polymorphism (ApaI) and VD deficiency are not associated with the risk of preeclampsia.

Reference equations for evaluation of spirometry function tests in South Asia, and among South Asians living in other countries.

BACKGROUND: There are few data to support accurate interpretation of spirometry data in South Asia, a major global region with a high reported burden of chronic respiratory disease. METHOD: We measured lung function in 7453 healthy men and women aged ≥18 years, from Bangladesh, North India, South India, Pakistan and Sri Lanka, as part of the South Asia Biobank study. First, we assessed the accuracy of existing equations for predicting normal forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC ratio. Then, we used our data to derive (n=5589) and internally validate (n=1864) new prediction equations among South Asians, with further external validation among 339 healthy South Asians living in Singapore. RESULTS: The Global Lung Initiative (GLI) and National Health and Nutrition Examination Survey consistently overestimated expiratory volumes (best fit GLI-African American, mean±sd z-score: FEV1 -0.94±1.05, FVC -0.91±1.10; n=7453). Age, height and weight were strong predictors of lung function in our participants (p<0.001), and sex-specific reference equations using these three variables were highly accurate in both internal validation (z-scores: FEV1 0.03±0.99, FVC 0.04±0.97, FEV1/FVC -0.03±0.99) and external validation (z-scores: FEV1 0.31±0.99, FVC 0.24±0.97, FEV1/FVC 0.16±0.91). Further adjustment for study regions improves the model fit, with highest accuracy for estimation of region-specific lung function in South Asia. CONCLUSION: We present improved equations for predicting lung function in South Asians. These offer the opportunity to enhance diagnosis and management of acute and chronic lung diseases in this major global population.

Tf2O- and Cu(OTf)2-Assisted Acylamination Reaction of Unactivated Alcohols with Nitriles: A One-Pot P(IV) Activation, Stereoretention in Cycloalkanols and Deprotection Approach.

Described herein is a simple, novel, one-pot acylamination reaction of unactivated alcohols. This reaction employs the combination of PCl3 and triflic anhydride (Tf2O) or copper triflate Cu(OTf)2, which serves as a source of P(IV)-activated complex for nitriles to react under the Ritter-type mechanism. The synthetic utility of Tf2O-promoted reactions was demonstrated by its effectiveness to generate different acylaminated products. By employing Cu(OTf)2, this method represents a rare example of α-selective acylamination reaction. With chiral cycloalkanols, using the Cu(OTf)2-promoted procedure, acylaminated products are formed with complete retention of configuration. The synthetic utility of the copper-assisted reaction in acetonitrile was readily demonstrated as a mild deprotection strategy.

Knockout of the entire family of AITR genes in Arabidopsis leads to enhanced drought and salinity tolerance without fitness costs.

BACKGORUND: Environmental stresses including abiotic stresses and biotic stresses limit yield of plants. Stress-tolerant breeding is an efficient way to improve plant yield under stress conditions. Genome editing by CRISPR/Cas9 can be used in molecular breeding to improve agronomic traits in crops, but in most cases, with fitness costs. The plant hormone ABA regulates plant responses to abiotic stresses via signaling transduction. We previously identified AITRs as a family of novel transcription factors that play a role in regulating plant responses to ABA and abiotic stresses. We found that abiotic stress tolerance was increased in the single, double and triple aitr mutants. However, it is unclear if the increased abiotic stress tolerance in the mutants may have fitness costs. RESULTS: We report here the characterization of AITRs as suitable candidate genes for CRISPR/Cas9 editing to improve plant stress tolerance. By using CRISPR/Cas9 to target AITR3 and AITR4 simultaneously in the aitr256 triple and aitr1256 quadruple mutants respectively, we generated Cas9-free aitr23456 quintuple and aitr123456 sextuple mutants. We found that reduced sensitivities to ABA and enhanced tolerance to drought and salt were observed in these mutants. Most importantly, plant growth and development was not affected even in the aitr123456 sextuple mutants, in whom the entire AITR family genes have been knocked out, and the aitr123456 sextuple mutants also showed a wild type response to the pathogen infection. CONCLUSIONS: Our results suggest that knockout of the AITR family genes in Arabidopsis enhanced abiotic stress tolerance without fitness costs. Considering that knock-out a few AITRs will lead to enhanced abiotic stress tolerance, that AITRs are widely distributed in angiosperms with multiple encoding genes, AITRs may be targeted for molecular breeding to improve abiotic stress tolerance in plants including crops.

Involvement of ABA Responsive SVB Genes in the Regulation of Trichome Formation in Arabidopsis.

Trichome formation in Arabidopsis is regulated by several key regulators, and plants hormones such as gibberellin, salicylic acid, jasmonic acid and cytokinins have been shown to regulate trichome formation by affecting the transcription or activities of the key regulators. We report here the identification of two abscisic acid (ABA) responsive genes, SMALLER TRICHOMES WITH VARIABLE BRANCHES (SVB) and SVB2 as trichome formation regulator genes in Arabidopsis. The expression levels of SVB and SVB2 were increased in response to ABA treatment, their expression levels were reduced in the ABA biosynthesis mutant aba1-5, and they have similar expression pattern. In addition to the trichome defects reported previously for the svb single mutant, we found that even though the trichome numbers were largely unaffected in both the svb and svb2 single mutants generate by using CRISPR/Cas9 gene editing, the trichome numbers were greatly reduced in the svb svb2 double mutants. On the other hand, trichome numbers were increased in SVB or SVB2 overexpression plants. RT-PCR results show that the expression of the trichome formation key regulator gene ENHANCER OF GLABRA3 (EGL3) was affected in the svb svb2 double mutants. Our results suggest that SVB and SVB2 are ABA responsive genes, and SVB and SVB2 function redundantly to regulate trichome formation in Arabidopsis.

GCN5 modulates trichome initiation in Arabidopsis by manipulating histone acetylation of core trichome initiation regulator genes.

KEY MESSAGE: Histone acetyltransferase GCN5 affects trichome initiation via mediating the expression of some core trichome initiation regulator genes in Arabidopsis. GENERAL CONTROL NON-REPRESSED PROTEIN5 (GCN5), a histone acetyltransferase involved in the regulation of cell differentiation, organ development, secondary metabolism, and plant responses to abiotic stresses, has recently been shown to modulate trichome branching in Arabidopsis. Here, we provide evidence that GCN5 is also involved in the regulation of trichome initiation. We found that mutation of GCN5 led to increased leaf trichome density in Arabidopsis. Quantitative RT-PCR results showed that the expression of CPC, GL1, GL2, and GL3, four well-known core trichome initiation regulator genes, was decreased in the gcn5 mutants. ChIP assays indicated that these four trichome initiation regulator genes are direct targets of GCN5. Consistent with these results, GCN5-mediated H3K14/K9 acetylation levels on the TSS regions of these genes were decreased. On the other hand, leaf trichome density was reduced in plants overexpressing GCN5, and both the transcript levels and GCN5-binding enrichments of CPC, GL1, GL2, and GL3 genes were elevated. Taken together, these data suggests that GCN5 affects trichome initiation by modulating the transcription activities of trichome initiation regulator genes via H3K9/14 acetylation.

Genome Editing to Integrate Seed Size and Abiotic Stress Tolerance Traits in Arabidopsis Reveals a Role for DPA4 and SOD7 in the Regulation of Inflorescence Architecture.

Both seed size and abiotic stress tolerance are important agronomic traits in crops. In Arabidopsis, two closely related transcription repressors DPA4 (Development-Related PcG Target in the APEX4)/NGAL3 and SOD7 (Suppressor of da1-1)/NGAL2 (NGATHA-like protein) function redundantly to regulate seed size, which was increased in the dpa4 sod7 double mutants. Whereas ABA-induced transcription repressors (AITRs) are involved in the regulation of ABA signaling and abiotic stress tolerance, Arabidopsis aitr2 aitr5 aitr6 (aitr256) triple mutant showed enhanced tolerance to drought and salt. Here we performed CRISPR/Cas9 genome editing to disrupt DPA4 and SOD7 in aitr256 mutant, trying to integrate seed size and abiotic stress tolerance traits in Arabidopsis, and also to examine whether DPA4 and SOD7 may regulate other aspects of plant growth and development. Indeed, seed size was increased in the dpa4 sod7 aitr256 quintuple mutants, and enhanced tolerance to drought was observed in the mutants. In addition, we found that shoot branching was affected in the dpa4 sod7 aitr256 mutants. The mutant plants failed to produce secondary branches, and flowers/siliques were distributed irregularly on the main stems of the plants. Floral organ number and fertility were also affected in the dpa4 sod7 aitr256 mutant plants. To examine if these phenotypes were dependent on loss-of-function of AITRs, dpa4 sod7 double mutants were generated in Col wild type background, and we found that the dpa4 sod7 mutant plants showed a phenotype similar to the dpa4 sod7 aitr256 quintuple mutants. Taken together, our results indicate that the integration of seed size and abiotic stress tolerance traits by CRISPR/Cas9 editing was successful, and our results also revealed a role of DPA4 and SOD7 in the regulation of inflorescence architecture in Arabidopsis.

Report: Phytochemical screening and antimicrobial activities of red silk cotton tree (Bombax ceiba L.).

The present study was conducted to investigate the phytochemical screening and antimicrobial activities of stem bark of Bombax ceiba L. The methanol extract was subjected to qualitative phytochemical screening using standard procedures. The results indicated the presence of alkaloids, tannins, glycosides, reducing sugar, saponins, phlobatanins and terpenoids. The antimicrobial activity was measured by disc diffusion method. Data revealed that Pseudomonas aeruginosa was inhibited by both methanol and ethanol extracts at the concentration of 2mg disc-1 {21.8mm (68.12%) and 21.3mm (66.56%)}. Similarly, methanol extract reduced the growth of Bacillus subtilis by 17.1mm (74.34%) at the concentration of 1 mg disc-1. However, ethanol extract showed a good activity of 18mm (121.6%) and 20.6mm (112.5%) against Xanthomonas maltophilia at concentrations of 1 and 2 mg disc-1, respectively. Aqueous extract showed 16 mm (53.33% Z.I) against Escherichia coli at 2 mg disc-1. Klebsiella pneumoniae was found resistant to all of the three extracts, while the growth of Candida albicans was inhibited by methanol through 16.5 mm (58.92% Z.I) at 1 mg disc-1. The above study concluded the medicinal potential of B. ceiba.

Ponseti Technique For Management Of Congenital Idiopathic Club Foot.

BACKGROUND: Clubfoot or congenital talipes equinovarus, is a congenital deformity of the foot. It consists of cavus, adduction, varus and equinus. This is due to medial displacement of navicular and calcaneus around the talus. Talus is in equinus. Medial deviation of the head and neck of talus is due to force of calcaneus on talus. METHODS: This descriptive case series study was conducted at Orthopaedic unit, Ayub Teaching Hospital, Abbottabad from 1st August 2015 to 31st January 2016 to determine the frequency of idiopathic clubfoot correction, by using the Ponseti method. A total of 177, unilateral and bilateral clubfeet, from both genders were studied. Patients between age of 2 weeks to 2 years were included in the study. Basic pirani score six (06) who were previously untreated were included in the study. Syndromic patients, previously treated and patients with associated neuro-mascular disorders were excluded from the study. Patients who were corrected with serial castings, were put in foot abduction brace. Those who needed some sort of surgery underwent surgery. All the data was collected in the proforma and analysed by SPSS version 16.00. RESULTS: A total of 177 clubfeet were included in the study. Mean age of the patients was 10.28±7.45 ranging from 2 weeks 2 years. There were 93 (52.5%) male and 84 (43.5%) female out of total 177 patients. Of these 20 patients were corrected with serial casting only while 150 patients underwent percutaneous tenotomy, which is a minor procedure and done on out -patient department basis. After correction, the feet were put in 70 degree of abduction in abduction brace. Only 7 patients required some sort of surgery, more than tenotomy. CONCLUSIONS: Ponseti is very effective, economical and non-invasive way of treating congenital idiopathic clubfoot. Only resistant cases may need some sort of extensive surgery.

Surgical Site Infection In Orthopaedic Implants And Its Common Bacteria With Their Sensitivities To Antibiotics, In Open Reduction Internal Fixation.

BACKGROUND: Surgical site infection in orthopaedic implants is a major problem, causing long hospital stay, cost to the patient and is a burden on health care facilities. It increases rate of nonunion, osteomyelitis, implant failure, sepsis, multiorgan dysfunction and even death. Surgical site infection is defined as pain, erythema, swelling and discharge from wound site. Surgical site infection in orthopaedic implants is more challenging to the treating orthopaedic surgeon as the causative organism is protected by a biofilm over the implant's surface. Antibiotics cannot cross this film to reach the bacteria's, causing infection. METHODS: This descriptive case series study includes 132 patients of both genders with ages between 13-60 years conducted at Orthopaedic Unit, Ayub Medical College, Abbottabad from 1st October 2015 to 31st March 2016. Patients with close fractures of long bones were included in the study to determine the frequency of surgical site infection in orthopaedic implants and the type of bacteria involved and their sensitivity to various antibiotics. All implants were of stainless steel. The implants used were Dynamic hip screws, Dynamic compression screws, plates, k-wires, Interlocking nails, SIGN nails, Austin Moore prosthesis and tension band wires. Pre-op and post-op antibiotics used were combination of Sulbactum and Cefoperazone which was given 1 hour before surgery and continued for 72 hours after surgery. Patients were followed up to 4 weeks. Pus was taken on culture stick, from those who developed infection. Results were entered in the pro forma. RESULTS: A total of 132 patients of long bone fractures, who were treated with open reduction and internal fixation, were studied. Only 7 patients developed infection. Staphylococcus Aureus was isolated from all 7 patients. Staphylococcus aureus was sensitive to Linezolid, Fusidic Acid, and vancomycin. Cotrimoxazole, tetracycline, Gentamycin and Clindamycin were partially effective. CONCLUSIONS: Surgical Site Infection is common in orthopaedic implants, occurring in 5.30% cases. Staphylococcus aureus is the common bacteria, causing it.

Upper And Lower Limbs Disability And Personality Traits.

BACKGROUND: It is believed that the study of personality has the potentials to enhance our prognostic abilities and can better to expose the etiology of mental illness through the relationship of revealed mechanisms. The focus of this study was to investigate and compare the habitual patterns of behavior, thought and emotions of upper and lower limb physically disabled students in terms of personality traits. METHODS: This cross sectional study consisted of 100 upper limbs and lower limbs disabled students taken from Kingston school Inclusive Education System Abottabad, Mashal special education system Haripur, Syed Ahmed Shaheed special education center Abottabad, Al-Munir Foundation Mansehra and Hera Special Education System Haripur and 100 normal students taken from Islamic International School Abottabad, Falcon Public School Haripur, Iqra Academy Mansehra and Alhamd International School Haripur of Hazara Division by purposive sampling technique. This study was conducted during the month of June 2013 to May 2014. Goldberg five big personality scale was used for measuring personality traits of physically disabled and normal students. RESULTS: The significant difference of personality traits scores between physically disabled students (M = 139.2, SD=12.0) and normal students (M=184.5, SD=13.2), t (198) =25.3, p<.05 was observed. CONCLUSIONS: Normal students have high scores as compared to physically disabled students on big five traits, i.e., Extraversion, Agreeableness, Conscientiousness, Emotional Stability and Openness to Experience.

Prospective cohort study of a new vacuum delivery device to assist with complicated labour in low-resource settings.

OBJECTIVES: Currently available vacuum devices used to assist women undergoing complicated labour are unsuitable for use in low-resource settings. The objective of this study was to evaluate the safety and feasibility of a new low-cost vacuum device, named Koohi Goth Vacuum Delivery System (KGVDS), designed for use in low-resource settings. METHODS: A hospital-based, multicentre, prospective cohort study with no control group was conducted in Karachi, Pakistan. After training, KGVDS devices were made available for use by labour room staff at their discretion when instrumental delivery was indicated. Women to whom KGVDS was applied were followed from the start of labour until discharge. Feasibility was assessed in terms of successful expulsion of the foetal head following application of KGVDS and ease of use ratings. Safety was assessed by observing maternal and newborn post-delivery outcomes prior to discharge. RESULTS: Koohi Goth Vacuum Delivery System was applied to 137 women requiring instrumental delivery, of whom 111 (81%; 95% CI = 74-88%) successfully expelled the foetal head assisted by KGVDS and 103 (75%) stated that they would agree to use KGVDS again. There were no serious maternal or neonatal injuries or infections related to KGVDS use. The mean score for 'ease of use' given by doctors and midwives using the device was 8 of 10. CONCLUSIONS: Koohi Goth Vacuum Delivery System was feasible and safe to use for assisting complicated deliveries in low-resource hospitals in this initial evaluation. Our results indicate that this new device may have the potential to improve birth outcomes in settings where most mortality occurs and that further evaluations should be conducted.

Quantitatively evaluating the effect of social barriers: a case-control study of family members' opposition and women's intention to use contraception in Pakistan.

BACKGROUND: Uptake of family planning services in Pakistan has remained slow over the past decade despite a rapid increase in availability and awareness, indicating that social barriers may be preventing uptake. Social barriers such as opposition by family members have largely been studied qualitatively; there is a lack of quantitative evidence about the effect of different family members' opposition on women's intention to use contraceptives. The objective of this study was to quantitatively evaluate the effect of family members' opposition to family planning on intention to use contraception amongst poor women in Pakistan who have physical access to family planning services. METHODS: An unmatched case control study (nested within a larger cohort study) was conducted in two public hospitals in Karachi, Pakistan. Univariable and multivariable logistic regression analyses were conducted to compare risk factors between women that were not intending to use any contraceptive methods in the future (cases) and women that were planning to use contraceptive methods (controls). RESULTS: 248 cases and 496 controls were included in the study. Negative contraceptive intent was associated with no knowledge of contraception (AOR = 3.79 [2.43-5.90]; p < 0.001), husband's opposition (AOR = 21.87 [13.21-36.21]; p < 0.001) and mother-in-law's opposition (AOR = 4.06 [1.77-9.30]; p < 0.001). CONCLUSIONS: This study is the first to quantitatively assess the effect of opposition by different family members on women's contraceptive intent in Pakistan. Our results indicate that of all family members, husband's opposition has the strongest effect on women's intention to use contraception, even when the women have knowledge of and physical access to family planning services.

mRNA secondary structure engineering of Thermobifida fusca endoglucanase (Cel6A) for enhanced expression in Escherichia coli.

The sequence and structure of mRNA plays an important role in solubility and expression of the translated protein. To divulge the role of mRNA secondary structure and its thermodynamics in the expression level of the recombinant endoglucanase in Escherichia coli, 5'-end of the mRNA was thermodynamically optimized. Molecular engineering was done by introducing two silent synonymous mutations at positions +5 (UCU with UCC) and +7 (UUC with UUU) of the 5'-end of mRNA to relieve hybridization with ribosomal binding site. Two variants of glycoside hydrolase family six endoglucanase, wild type (cel6A.wt) and mutant (cel6A.mut) from Thermobifida fusca were expressed and characterized in E. coli using T7 promoter-based expression vector; pET22b(+). Enhanced expression level of engineered construct (Cel6A.mut) with ∆G = -2.7 kcal mol(-1)was observed. It showed up to ~45 % higher expression as compared to the wild type construct (Cel6A.wt) having ∆G = -7.8 kcal mol(-1) and ~25 % expression to the total cell proteins. Heterologous protein was purified by heating the recombinant E. coli BL21 (DE3) CodonPlus at 60 °C. The optimum pH for enzyme activity was six and optimum temperature was 60 °C. Maximum activity was observed 4.5 Umg(-1) on CMC. Hydrolytic activity was also observed on insoluble substrates, i.e. RAC (2.8 Umg(-1)), alkali treated bagass (1.7 Umg(-1)), filter paper (1.2 Umg(-1)) and BMCC (0.3 Umg(-1)). Metal ions affect endoglucanase activity in different ways. Only Fe(2+) exhibited 20.8 % stimulatory effects on enzyme activity. Enzyme activity was profoundly inhibited by Hg2(+) (91.8 %).

How psychiatrists should introduce themselves in the first consultation: an experimental study.

BACKGROUND: How psychiatrists introduce themselves in the first consultation may influence the therapeutic relationship. There is no evidence about what type of introduction patients prefer. AIMS: To assess experimentally patients' preferences for how psychiatrists introduce themselves. METHOD: Twelve psychiatrists were filmed, each with three different introductions: stating name, profession and reason for consultation; the same, plus information on what will happen during the consultation; and the same, plus disclosure of a personal difficulty. Six randomly selected videos, of different psychiatrists, two of each type of introduction, were rated by each of 120 psychiatric in- and out-patients on Likert-type scales. RESULTS: Patients gave the most positive ratings to psychiatrists who introduced themselves with information about what will happen in the consultation rather than ones with briefer introductions or with additional personal disclosure (P = 0.002). Preferences were similar in different subgroups. CONCLUSIONS: Psychiatrists should introduce themselves with information about what they intend to do in the consultation, but without personal disclosure.

BF3-Et2O promoted bifunctionalization of aldehydes for the synthesis of arylmethyl substituted organophosphorus compounds.

A simple and efficient protocol for the synthesis of arylmethyl substituted organophosphorus compounds is presented. This method involves the reaction of diphenyl phosphite with aldehydes in the presence of BF3-Et2O. In this method, BF3-Et2O plays a dual role, as it facilitates the generation of both hydrophosphonylated intermediate and phenol from diphenyl phosphite. A significant feature of this approach is its tolerance to the presence of external nucleophiles, such as phenol, aliphatic thiols, indole and 3-methylanisole. The simplicity of the reaction conditions and the high yields achieved make this method promising for applications in areas where phosphonate compounds are of interest.

BF3-Et2O Promoted Heteronucleophilic Addition Reactions for the Synthesis of Unsymmetrical gem-Diarylmethyl Thioethers.

Herein, we present the BF3/BF4- mediated activation of diphenyl phosphite for the formation of thionium ions from aldehydes and thiophenols. These reactive species subsequently undergo reaction with in situ generated phenol, resulting in the synthesis of diarylmethyl thioethers. It was demonstrated that the addition of external phenol in the reaction produced unsymmetrical gem-diarylmethyl thioethers in good yields.

Modified W-type configuration for a single-phase reduced parts count 81-level inverter.

The technology of modern power systems is revolutionizing as renewable energy sources are being integrated with electric power grids. In the form of inverters, power electronic converters are becoming an integral part of power systems due to their massive demand for grid integration of photovoltaic (PV) systems. Existing multilevel inverter topologies either require an output filter to get a sinusoidal voltage or generate a higher number of output voltage levels at the expense of many hardware resources. This paper presents a new single-phase 81-level inverter configuration with the name given as 'Modified W-Type Multilevel Inverter'. The proposed inverter configuration uses only eighteen power switches and four DC voltage sources to generate an 81-level output voltage approaching a sinusoidal waveform without an output filter. The general design equations are developed to calculate the number of switches, the number of voltage levels, and the number of DC sources for the proposed configuration. Loss and efficiency analysis is carried out that verifies a good practical efficiency of the proposed inverter configuration during the dynamic operation. A comparative analysis with the existing MLI topologies is also carried out that validates the effectiveness and novelty in reducing parts count and higher number of voltage levels. The proposed topology offers 1.04% total harmonic distortion of the output voltage which is within the benchmarks specified for grid integration without any filter requirements. The proposed inverter configuration is simulated in MATLAB/Simulink, and the results are validated by the design and development of a hardware prototype.